initial commit

SQUASHFS/squashfs-tools-4.4/RELEASE-READMEs/README-4.3

+	SQUASHFS 4.3 - A squashed read-only filesystem for Linux
+
+	Copyright 2002-2014 Phillip Lougher <phillip@lougher.demon.co.uk>
+
+	Released under the GPL licence (version 2 or later).
+
+Welcome to Squashfs 4.3.  This is the first release in over 3 years, and
+there are substantial improvements to stability, new compression options
+and compressors, speed optimisations, and new options for Mksquashfs/Unsquashfs.
+
+This is a tools only release, support for Squashfs filesystems is
+in mainline (2.6.29 and later).
+
+Changes in Squashfs-tools 4.3
+-----------------------------
+
+1. Stability improvements.  Better checking of user input for out of
+   range/invalid values.  Better handling of corrupted Squashfs filesystems
+   (Mksquashfs append mode, and Unsquashfs).  Better handling of buffer
+   overflow/underflow.
+
+2. GZIP compressor now supports compression options, allowing different
+   compression levels to be used.
+
+3. Rewritten LZO compressor with compression options, allowing different
+   LZO algorithms and different compression levels to be used.
+
+4. New LZ4 compressor (note not yet in mainline kernel)
+
+5. Better default memory usage for Mksquashfs.  Mksquashfs by default now
+   uses 25% of physical memory.
+
+6. Duplicate checking in Mksquashfs further optimised.  With certain
+   "problem filesystems" greater than 2x performance improvement.
+   Filesystems with a lot of duplicates should see at least 10-20% speed
+   improvement.
+
+7. The -stat option in Unsquashfs now displays the compression options
+   used to generate the original filesystem.  Previously -stat only displayed
+   the compression algorithm used.
+
+8. The file being compressed/uncompressed in Mksquashfs/Unsquashfs is now
+   displayed if CTRL-\ (SIGQUIT from keyboard) typed.
+
+9. The status of the internal queues/caches in Mksquashfs/Unsquashfs is
+   now displayed if CTRL-\ (SIGQUIT from keyboard) is typed twice within
+   one second.  Normally only useful for "power users", but it can be
+   used to discover if there's any bottlenecks affecting performance
+   (the bottleneck will normally be the compressors/fragment compressors).
+
+10. Miscellaneous new options for Mksquashfs/Unsquashfs to fine tune behaviour.
+
+11. Fixes for CVE-2012-4024 and CVE-2012-4025.
+
+Compatiblity
+------------
+
+Mksquashfs 4.3 generates 4.0 filesystems.  These filesystems are fully
+compatible/interchangable with filesystems generated by Mksquashfs 4.0 and are
+mountable on 2.6.29 and later kernels.
+
+Compressors
+-----------
+
+New compression options and compressors are now supported.
+
+The new options and compressors are:
+
+1. gzip
+	  -Xcompression-level <compression-level>
+		<compression-level> should be 1 .. 9 (default 9)
+	  -Xwindow-size <window-size>
+		<window-size> should be 8 .. 15 (default 15)
+	  -Xstrategy strategy1,strategy2,...,strategyN
+		Compress using strategy1,strategy2,...,strategyN in turn
+		and choose the best compression.
+		Available strategies: default, filtered, huffman_only,
+		run_length_encoded and fixed
+
+2. lzo
+	  -Xalgorithm <algorithm>
+		Where <algorithm> is one of:
+			lzo1x_1
+			lzo1x_1_11
+			lzo1x_1_12
+			lzo1x_1_15
+			lzo1x_999 (default)
+	  -Xcompression-level <compression-level>
+		<compression-level> should be 1 .. 9 (default 8)
+		Only applies to lzo1x_999 algorithm
+
+3. lz4
+	  -Xhc
+		Compress using LZ4 High Compression
+
+The compression specific options are, obviously, specific to the compressor
+in question, and you should read the compressor documentation and check
+their web sites to understand their behaviour.
+
+In general the defaults used by Mksquashfs for each compressor are optimised
+to give the best performance for each compressor, where what constitutes
+best depends on the compressor.  For gzip/xz best means highest compression
+(trying multiple filters/strategies can improve compression, but this is
+extremely expensive computationally, and hence, not suitable for the defaults),
+for LZO/LZ4 best means a tradeoff between compression and (de)-compression
+overhead (LZO/LZ4 by definition are intended for weaker processors).
+
+New Mksquashfs options
+----------------------
+
+1. -mem <size>
+
+  Set the amount of memory used by Mksquashfs to <size> bytes.  G/M and K
+  post-fixes are supported.
+
+  By default Mksquashfs uses 25% of the physical memory.  Increasing
+  this with the -mem option can increase performance (note it does not have
+  any effect on compression).  Reducing it can prevent thrashing if the
+  system is busy and there is not 25% of physical memory free (again, note
+  it does not have any effect on compression).
+
+2. -exit-on-error
+
+  By default Mksquashfs treats certain errors as benign, if these
+  errors occur Mksquashfs prints the error on the console but continues.
+  These errors are typically failure to read a file from the source filesystem.
+  This is deliberate, in many cases users prefer Mksquashfs to flag
+  the error but continue rather than abort what may be hours of compression.
+
+  But there are times where failure to read any file is considered critical,
+  and users (especially in the case of automated scripts where the
+  errors output to the console may be missed) prefer Mksquashfs to exit.
+
+  The new -exit-on-error option can be used in this scenario.  This option
+  makes Mksquashfs treat all benign errors as fatal.
+
+3. -progress
+
+  By default if -info is specified, the progress bar is disabled as it gets
+  in the way.  Occasionally you might want the progress bar enabled whilst
+  -info is enabled.  This option forces Mksquashfs to output the progress
+  bar when -info is specified.
+
+4. -Xhelp
+
+  Display the usage text for the currently selected compressor.
+
+New Unsquashfs options
+----------------------
+
+1. -u[ser-xattrs]
+
+  Only write user xattrs.  This forces Unsquashfs to ignore system xattrs.
+  This is useful when Unsquashing a filesystem as a non-root user, and the
+  filesystem contains system xattrs which are only writable by root.
+
+Major bugs fixed
+----------------
+
+1. If Mksquashfs ran out of space in the destination filesystem, this
+   would not cause Mksquashfs to immediately abort, and Mksquashfs would
+   continue to process the source filesystem.  Mksquashfs now immediately
+   aborts on out of space in the destination filesystem.
+
+2. Unsquashfs ignored the maximum number of open files limit, and if that
+   was lower than the default limit for Linux, it would run out of file
+   descriptors.  Unsquashfs now limits the number of open files to the
+   limit currently in force (e.g. specified by setrlimit).
+
+3. If huge numbers of dynamic pseudo files were specified, Mksquashfs
+   could exceed the maximum number of open files limit.  This was because
+   Mksquashfs created all the dynamic file processes up front before
+   commencing source filesystem reading and compression.  Mksquashfs
+   now creates the dynamic file processes on demand whilst reading
+   and compressing the source filesystem, thus limiting the number of
+   dynamic pseudo file processes in existence at any one time.
+
+4. When outputting Unsquashfs used to set the permissions of directories
+   as it recursively descended.  This in hindsight had an obvious oversight,
+   if a directory had only read permission (or was otherwise restricted), then
+   Unsquashfs would fail to write its contents when descending into it.  Fixed
+   by setting directory permissions as Unsquashfs recursively unwinds.

SQUASHFS/squashfs-tools-4.4/RELEASE-READMEs/pseudo-file.example

+# Pseudo file example
+
+# Mksquashfs supports pseudo files, these allow fake files, directories,
+# character and block devices to be specified and added to the Squashfs
+# filesystem being built, rather than requiring them to be present in the
+# source directories.
+#
+# This, for example, allows device nodes to be added to the filesystem without
+# requiring root access.
+
+# Mksquashfs 4.1 adds support for "dynamic pseudo files" and a modify operation.
+# Dynamic pseudo files allow files to be dynamically created when Mksquashfs
+# is run, their contents being the result of running a command or piece of
+# shell script.  The modifiy operation allows the mode/uid/gid of an existing
+# file in the source filesystem to be modified.
+
+# Two Mksquashfs options are supported, -p allows one pseudo file to be
+# specified #on the command line, and -pf allows a pseudo file to be specified
+# containing a list of pseduo definitions, one per line.
+
+# Pseudo file examples
+# Run mkquashfs . /tmp/img -pf pseudo-file.examples
+# to see their effect
+
+# Creating dynamic file examples
+
+# Create a file "dmesg" containing the output from dmesg.
+dmesg f 444 root root dmesg
+
+
+# Create a file RELEASE containing the release name, date, build host, and
+# an incrementing version number.  The incrementing version is a side-effect
+# of executing the shell script, and ensures every time Mksquashfs is run a
+# new version number is used without requiring any other shell scripting.
+RELEASE f 444 root root \
+		if [ ! -e /tmp/ver ]; then \
+			echo 0 > /tmp/ver; \
+		fi; \
+                ver=`cat /tmp/ver`; \
+                ver=$((ver +1)); \
+                echo $ver > /tmp/ver; \
+                echo -n "release x.x"; \
+                echo "-dev #"$ver `date` "Build host" `hostname`
+
+
+# Copy 10K from the device /dev/sda1 into the file input.  Ordinarily
+# Mksquashfs given a device, fifo, or named socket will place that special file
+# within the Squashfs filesystem, this allows input from these special
+# files to be captured and placed in the Squashfs filesystem.
+input f 444 root root dd if=/dev/sda1 bs=1024 count=10
+
+
+# Creating a block or character device examples
+
+# Create a character device "chr_dev" with major:minor 100:1 and
+# a block device "blk_dev" with major:minor 200:200, both with root
+# uid/gid and a mode of rw-rw-rw.
+chr_dev c 666 root root 100 1
+blk_dev b 666 0 0 200 200
+
+
+# Creating a directory example
+
+# create a directory "pseudo_dir" with root uid/gid and mode of r--r--r--.
+pseudo_dir d 444 root root
+
+
+# Modifying attributes of an existing file exmaple
+
+# Change the attributes of the file "INSTALL" in the filesystem to have
+# root uid/gid and a mode of rw-rw-rw, overriding the attributes obtained
+# from the source filesystem.
+INSTALL m 666 root root
+

SQUASHFS/squashfs-tools-4.4/USAGE

+	SQUASHFS 4.4 - A squashed read-only filesystem for Linux
+
+	Copyright 2002-2019 Phillip Lougher <phillip@squashfs.org.uk>
+
+	Released under the GPL licence (version 2 or later).
+
+Welcome to Squashfs version 4.4.  Please read the README-4.3 and CHANGES files
+for details of changes.
+
+Squashfs is a highly compressed read-only filesystem for Linux.
+It uses either gzip/xz/lzo/lz4/zstd compression to compress both files, inodes
+and directories.  Inodes in the system are very small and all blocks are
+packed to minimise data overhead. Block sizes greater than 4K are supported
+up to a maximum of 1Mbytes (default block size 128K).
+
+Squashfs is intended for general read-only filesystem use, for archival
+use (i.e. in cases where a .tar.gz file may be used), and in constrained
+block device/memory systems (e.g. embedded systems) where low overhead is
+needed.
+
+1. SQUASHFS OVERVIEW
+--------------------
+
+1. Data, inodes and directories are compressed.
+
+2. Squashfs stores full uid/gids (32 bits), and file creation time.
+
+3. In theory files up to 2^64 bytes are supported.  In theory filesystems can
+   be up to 2^64 bytes.
+
+4. Inode and directory data are highly compacted, and packed on byte
+   boundaries.  Each compressed inode is on average 8 bytes in length
+   (the exact length varies on file type, i.e. regular file, directory,
+   symbolic link, and block/char device inodes have different sizes).
+
+5. Squashfs can use block sizes up to 1Mbyte (the default size is 128K).
+   Using 128K blocks achieves greater compression ratios than the normal
+   4K block size.
+
+6. File duplicates are detected and removed.
+
+7. Filesystems can be compressed with gzip, xz (lzma2), lzo, lz4
+   or zstd compression algorithms.
+
+
+1.1 Introducing reproducible builds
+-----------------------------------
+
+Ever since Mksquashfs was parallelised back in 2006, there
+has been a certain randomness in how fragments and multi-block
+files are ordered in the output filesystem even if the input
+remains the same.
+
+This is because the multiple parallel threads can be scheduled
+differently between Mksquashfs runs.  For example, the thread
+given fragment 10 to compress may finish before the thread
+given fragment 9 to compress on one run (writing fragment 10
+to the output filesystem before fragment 9), but, on the next
+run it could be vice-versa.  There are many different scheduling
+scenarios here, all of which can have a knock on effect causing
+different scheduling and ordering later in the filesystem too.
+
+Mkquashfs doesn't care about the ordering of fragments and
+multi-block files within the filesystem, as this does not
+affect the correctness of the filesystem.
+
+In fact not caring about the ordering, as it doesn't matter, allows
+Mksquashfs to run as fast as possible, maximising CPU and I/O
+performance.
+
+But, in the last couple of years, Squashfs has become used in
+scenarios (cloud etc) where this randomness is causing problems.
+Specifically this appears to be where downloaders, installers etc.
+try to work out the differences between Squashfs filesystem
+updates to minimise the amount of data that needs to transferred
+to update an image.
+
+Additionally, in the last couple of years has arisen the notion
+of reproducible builds, that is the same source and build
+environment etc should be able to (re-)generate identical
+output.  This is usually for verification and security, allowing
+binaries/distributions to be checked for malicious activity.
+See https://reproducible-builds.org/ for more information.
+
+Mksquashfs from release 4.4 now generates reproducible images
+by default.  Images generated by Mksquashfs will be ordered
+identically to previous runs if the same input has been supplied,
+and the same options used.
+
+1.1.1 Dealing with timestamps
+
+Timestamps embedded in the filesystem will stiil cause differences.
+Each new run of Mksquashfs will produce a different mkfs (make filesystem)
+timestamp in the super-block.  Moreover if any file timestamps have changed
+(even if the content hasn't), this will produce a difference.
+
+To prevent timestamps from producing differences, the following
+new Mksquashfs options have been added.
+
+1.1.2 -mkfs-time <time>
+
+This option takes a positive time value (which is the number
+of seconds since the epoch of 1970-01-01 00:00:00 UTC), and sets
+the file system timestamp to that.
+
+Squashfs uses an unsigned 32-bit integer to store time, and the
+time given should be in that range.
+
+Obviously you can use the date command to convert dates into
+this value, i.e.
+
+% mksquashfs source source.sqsh -mkfs-time $(date +%s -d "Jan 1 2019 19:00")
+
+1.1.3 -all-time <time>
+
+This option takes a positive time value (which is the number
+of seconds since the epoch of 1970-01-01 00:00:00 UTC), and sets
+the timestamp on all files to that (but not the mkfs time).
+
+1.1.4 environment variable SOURCE_DATE_EPOCH
+
+As an alternative to the above command line options, you can
+set the environment variable SOURCE_DATE_EPOCH to a time value.
+
+This value will be used to set the mkfs time.  Also any
+file timestamps which are after SOURCE_DATE_EPOCH will be
+clamped to SOURCE_DATE_EPOCH.
+
+See https://reproducible-builds.org/docs/source-date-epoch/
+for more information.
+
+Note: both SOURCE_DATE_EPOCH and the command line options cannot
+be used at the same time.  They are different ways to do the same thing,
+and both have FORCE sematics which mean they can't be over-ridden
+elsewhere (otherwise it would defeat the purpose).
+
+1.1.5 -not-reproducible
+
+This option tells Mksquashfs that the files do not have to be
+strictly ordered.  This will make Mksquashfs behave like version 4.3.
+
+1.2 Extended attributes (xattrs)
+--------------------------------
+
+Squashfs filesystems now have extended attribute support.  The
+extended attribute implementation has the following features:
+
+1. Layout can store up to 2^48 bytes of compressed xattr data.
+2. Number of xattrs per inode unlimited.
+3. Total size of xattr data per inode 2^48 bytes of compressed data.
+4. Up to 4 Gbytes of data per xattr value.
+5. Inline and out-of-line xattr values supported for higher performance
+   in xattr scanning (listxattr & getxattr), and to allow xattr value
+   de-duplication.
+6. Both whole inode xattr duplicate detection and individual xattr value
+   duplicate detection supported.  These can obviously nest, file C's
+   xattrs can be a complete duplicate of file B, and file B's xattrs
+   can be a partial duplicate of file A.
+7. Xattr name prefix types stored, allowing the redundant "user.", "trusted."
+   etc. characters to be eliminated and more concisely stored.
+8. Support for files, directories, symbolic links, device nodes, fifos
+   and sockets.
+
+Extended attribute support is in 2.6.35 and later kernels.  Filesystems
+with extended attributes can be mounted on 2.6.29 and later kernels, the
+extended attributes will be ignored with a warning.
+
+2. USING SQUASHFS
+-----------------
+
+Squashfs filesystems should be mounted with 'mount' with the filesystem type
+'squashfs'.  If the filesystem is on a block device, the filesystem can be
+mounted directly, e.g.
+
+%mount -t squashfs /dev/sda1 /mnt
+
+Will mount the squashfs filesystem on "/dev/sda1" under the directory "/mnt".
+
+If the squashfs filesystem has been written to a file, the loopback device
+can be used to mount it (loopback support must be in the kernel), e.g.
+
+%mount -t squashfs image /mnt -o loop
+
+Will mount the squashfs filesystem in the file "image" under
+the directory "/mnt".
+
+3. MKSQUASHFS
+-------------
+
+3.1 Mksquashfs options and overview
+-----------------------------------
+
+As squashfs is a read-only filesystem, the mksquashfs program must be used to
+create populated squashfs filesystems.
+
+SYNTAX:mksquashfs source1 source2 ...  dest [options] [-e list of exclude
+dirs/files]
+
+Filesystem build options:
+-comp <comp>		select <comp> compression
+			Compressors available:
+				gzip (default)
+				lzo
+				lz4
+				xz
+				zstd
+-b <block_size>		set data block to <block_size>.  Default 128 Kbytes
+			Optionally a suffix of K or M can be given to specify
+			Kbytes or Mbytes respectively
+-reproducible		build images that are reproducible (default)
+-not-reproducible	build images that are not reproducible
+-mkfs-time <time>	set mkfs time to <time> which is an unsigned int
+-fstime <time>		synonym for mkfs-time
+-all-time <time>	set all inode times to <time> which is an unsigned int
+-no-exports		don't make the filesystem exportable via NFS
+-no-sparse		don't detect sparse files
+-no-xattrs		don't store extended attributes
+-xattrs			store extended attributes (default)
+-noI			do not compress inode table
+-noId			do not compress the uid/gid table (implied by -noI)
+-noD			do not compress data blocks
+-noF			do not compress fragment blocks
+-noX			do not compress extended attributes
+-no-fragments		do not use fragments
+-always-use-fragments	use fragment blocks for files larger than block size
+-no-duplicates		do not perform duplicate checking
+-all-root		make all files owned by root
+-root-mode <mode>	set root directory permissions to octal <mode>
+-force-uid <uid>	set all file uids to <uid>
+-force-gid <gid>	set all file gids to <gid>
+-nopad			do not pad filesystem to a multiple of 4K
+-keep-as-directory	if one source directory is specified, create a root
+			directory containing that directory, rather than the
+			contents of the directory
+
+Filesystem filter options:
+-p <pseudo-definition>	Add pseudo file definition
+-pf <pseudo-file>	Add list of pseudo file definitions
+			Pseudo definitions should be of the format
+				filename d mode uid gid
+				filename m mode uid gid
+				filename b mode uid gid major minor
+				filename c mode uid gid major minor
+				filename f mode uid gid command
+				filename s mode uid gid symlink
+-sort <sort_file>	sort files according to priorities in <sort_file>.  One
+			file or dir with priority per line.  Priority -32768 to
+			32767, default priority 0
+-ef <exclude_file>	list of exclude dirs/files.  One per line
+-wildcards		Allow extended shell wildcards (globbing) to be used in
+			exclude dirs/files
+-regex			Allow POSIX regular expressions to be used in exclude
+			dirs/files
+
+Filesystem append options:
+-noappend		do not append to existing filesystem
+-root-becomes <name>	when appending source files/directories, make the
+			original root become a subdirectory in the new root
+			called <name>, rather than adding the new source items
+			to the original root
+
+Mksquashfs runtime options:
+-version		print version, licence and copyright message
+-exit-on-error		treat normally ignored errors as fatal
+-recover <name>		recover filesystem data using recovery file <name>
+-no-recovery		don't generate a recovery file
+-quiet			no verbose output
+-info			print files written to filesystem
+-no-progress		don't display the progress bar
+-progress		display progress bar when using the -info option
+-processors <number>	Use <number> processors.  By default will use number of
+			processors available
+-mem <size>		Use <size> physical memory.  Currently set to 4096M
+			Optionally a suffix of K, M or G can be given to specify
+			Kbytes, Mbytes or Gbytes respectively
+
+Miscellaneous options:
+-root-owned		alternative name for -all-root
+-offset <offset>	Skip <offset> bytes at the beginning of <dest>.
+			Optionally a suffix of K, M or G can be given to specify
+			Kbytes, Mbytes or Gbytes respectively.
+			Default 0 bytes.
+-o <offset>		synonym for -offset
+-noInodeCompression	alternative name for -noI
+-noIdTableCompression	alternative name for -noId
+-noDataCompression	alternative name for -noD
+-noFragmentCompression	alternative name for -noF
+-noXattrCompression	alternative name for -noX
+
+-Xhelp			print compressor options for selected compressor
+
+Compressors available and compressor specific options:
+	gzip (default)
+	  -Xcompression-level <compression-level>
+		<compression-level> should be 1 .. 9 (default 9)
+	  -Xwindow-size <window-size>
+		<window-size> should be 8 .. 15 (default 15)
+	  -Xstrategy strategy1,strategy2,...,strategyN
+		Compress using strategy1,strategy2,...,strategyN in turn
+		and choose the best compression.
+		Available strategies: default, filtered, huffman_only,
+		run_length_encoded and fixed
+	lzo
+	  -Xalgorithm <algorithm>
+		Where <algorithm> is one of:
+			lzo1x_1
+			lzo1x_1_11
+			lzo1x_1_12
+			lzo1x_1_15
+			lzo1x_999 (default)
+	  -Xcompression-level <compression-level>
+		<compression-level> should be 1 .. 9 (default 8)
+		Only applies to lzo1x_999 algorithm
+	lz4
+	  -Xhc
+		Compress using LZ4 High Compression
+	xz
+	  -Xbcj filter1,filter2,...,filterN
+		Compress using filter1,filter2,...,filterN in turn
+		(in addition to no filter), and choose the best compression.
+		Available filters: x86, arm, armthumb, powerpc, sparc, ia64
+	  -Xdict-size <dict-size>
+		Use <dict-size> as the XZ dictionary size.  The dictionary size
+		can be specified as a percentage of the block size, or as an
+		absolute value.  The dictionary size must be less than or equal
+		to the block size and 8192 bytes or larger.  It must also be
+		storable in the xz header as either 2^n or as 2^n+2^(n+1).
+		Example dict-sizes are 75%, 50%, 37.5%, 25%, or 32K, 16K, 8K
+		etc.
+	zstd
+	  -Xcompression-level <compression-level>
+		<compression-level> should be 1 .. 22 (default 15)
+
+Source1 source2 ... are the source directories/files containing the
+files/directories that will form the squashfs filesystem.  If a single
+directory is specified (i.e. mksquashfs source output_fs) the squashfs
+filesystem will consist of that directory, with the top-level root
+directory corresponding to the source directory.
+
+If multiple source directories or files are specified, mksquashfs will merge
+the specified sources into a single filesystem, with the root directory
+containing each of the source files/directories.  The name of each directory
+entry will be the basename of the source path.   If more than one source
+entry maps to the same name, the conflicts are named xxx_1, xxx_2, etc. where
+xxx is the original name.
+
+To make this clear, take two example directories.  Source directory
+"/home/phillip/test" contains  "file1", "file2" and "dir1".
+Source directory "goodies" contains "goodies1", "goodies2" and "goodies3".
+
+usage example 1:
+
+%mksquashfs /home/phillip/test output_fs
+
+This will generate a squashfs filesystem with root entries
+"file1", "file2" and "dir1".
+
+example 2:
+
+%mksquashfs /home/phillip/test goodies output_fs
+
+This will create a squashfs filesystem with the root containing
+entries "test" and "goodies" corresponding to the source
+directories "/home/phillip/test" and "goodies".
+
+example 3:
+
+%mksquashfs /home/phillip/test goodies test output_fs
+
+This is the same as the previous example, except a third
+source directory "test" has been specified.  This conflicts
+with the first directory named "test" and will be renamed "test_1".
+
+Multiple sources allow filesystems to be generated without needing to
+copy all source files into a common directory.  This simplifies creating
+filesystems.
+
+The -keep-as-directory option can be used when only one source directory
+is specified, and you wish the root to contain that directory, rather than
+the contents of the directory.  For example:
+
+example 4:
+
+%mksquashfs /home/phillip/test output_fs -keep-as-directory
+
+This is the same as example 1, except for -keep-as-directory.
+This will generate a root directory containing directory "test",
+rather than the "test" directory contents "file1", "file2" and "dir1".
+
+The Dest argument is the destination where the squashfs filesystem will be
+written.  This can either be a conventional file or a block device.  If the file
+doesn't exist it will be created, if it does exist and a squashfs
+filesystem exists on it, mksquashfs will append.  The -noappend option will
+write a new filesystem irrespective of whether an existing filesystem is
+present.
+
+3.2 Changing compression algorithm and compression specific options
+-------------------------------------------------------------------
+
+By default Mksquashfs will compress using the gzip compression
+algorithm.  This algorithm offers a good trade-off between compression
+ratio, and memory and time taken to decompress.
+
+Squashfs also supports LZ4, LZO and XZ (LZMA2) compression.  LZO offers worse
+compression ratio than gzip, but is faster to decompress.  XZ offers better
+compression ratio than gzip, but at the expense of greater memory and time
+to decompress (and significantly more time to compress).  LZ4 is similar
+to LZO, but, support for it is not yet in the mainline kernel, and so
+its usefulness is currently limited to using Squashfs with Mksquashfs/Unsquashfs
+as an archival system like tar.
+
+If you're not building the squashfs-tools and kernel from source, then
+the tools and kernel may or may not have been built with support for LZ4, LZO or
+XZ compression.  The compression algorithms supported by the build of
+Mksquashfs can be found by typing mksquashfs without any arguments.  The
+compressors available are displayed at the end of the help message, e.g. 
+
+Compressors available and compressor specific options:
+	gzip (default)
+	  -Xcompression-level <compression-level>
+		<compression-level> should be 1 .. 9 (default 9)
+	  -Xwindow-size <window-size>
+		<window-size> should be 8 .. 15 (default 15)
+	  -Xstrategy strategy1,strategy2,...,strategyN
+		Compress using strategy1,strategy2,...,strategyN in turn
+		and choose the best compression.
+		Available strategies: default, filtered, huffman_only,
+		run_length_encoded and fixed
+	lzo
+	  -Xalgorithm <algorithm>
+		Where <algorithm> is one of:
+			lzo1x_1
+			lzo1x_1_11
+			lzo1x_1_12
+			lzo1x_1_15
+			lzo1x_999 (default)
+	  -Xcompression-level <compression-level>
+		<compression-level> should be 1 .. 9 (default 8)
+		Only applies to lzo1x_999 algorithm
+	lz4
+	  -Xhc
+		Compress using LZ4 High Compression
+	xz
+	  -Xbcj filter1,filter2,...,filterN
+		Compress using filter1,filter2,...,filterN in turn
+		(in addition to no filter), and choose the best compression.
+		Available filters: x86, arm, armthumb, powerpc, sparc, ia64
+	  -Xdict-size <dict-size>
+		Use <dict-size> as the XZ dictionary size.  The dictionary size
+		can be specified as a percentage of the block size, or as an
+		absolute value.  The dictionary size must be less than or equal
+		to the block size and 8192 bytes or larger.  It must also be
+		storable in the xz header as either 2^n or as 2^n+2^(n+1).
+		Example dict-sizes are 75%, 50%, 37.5%, 25%, or 32K, 16K, 8K
+		etc.
+	zstd
+	  -Xcompression-level <compression-level>
+		<compression-level> should be 1 .. 22 (default 15)
+
+If the compressor offers compression specific options (all the compressors now
+have compression specific options except the deprecated lzma1 compressor)
+then these options are also displayed (.i.e. in the above XZ is shown with two
+compression specific options).  The compression specific options are, obviously,
+specific to the compressor in question, and the compressor documentation and
+web sites should be consulted to understand their behaviour.  In general
+the Mksquashfs compression defaults for each compressor are optimised to
+give the best performance for each compressor, where what constitutes
+best depends on the compressor.  For gzip/xz best means highest compression,
+for LZO/LZ4 best means a tradeoff between compression and (de)-compression
+overhead (LZO/LZ4 by definition are intended for weaker processors).
+
+3.3 Changing global compression defaults used in mksquashfs
+-----------------------------------------------------------
+
+There are a large number of options that can be used to control the 
+compression in mksquashfs.  By and large the defaults are the most
+optimum settings and should only be changed in exceptional circumstances!
+Note, this does not apply to the block size, increasing the block size
+from the default of 128Kbytes will increase compression (especially
+for the xz compressor) and should increase I/O performance too.  However,
+a block size of greater than 128Kbytes may increase latency in certain
+cases (where the filesystem contains lots of fragments, and no locality
+of reference is observed).  For this reason the block size default is
+configured to the less optimal 128Kbytes.  Users should experiment
+with 256Kbyte sizes or above.
+
+The -noI, -noD and -noF options (also -noInodeCompression, -noDataCompression
+and -noFragmentCompression) can be used to force mksquashfs to not compress
+inodes/directories, data and fragments respectively.  Giving all options
+generates an uncompressed filesystem.
+
+The -no-fragments tells mksquashfs to not generate fragment blocks, and rather
+generate a filesystem similar to a Squashfs 1.x filesystem.  It will of course
+still be a Squashfs 4.0 filesystem but without fragments, and so it won't be
+mountable on a Squashfs 1.x system.
+
+The -always-use-fragments option tells mksquashfs to always generate
+fragments for files irrespective of the file length.  By default only small
+files less than the block size are packed into fragment blocks.  The ends of
+files which do not fit fully into a block, are NOT by default packed into
+fragments.  To illustrate this, a 100K file has an initial 64K block and a 36K
+remainder.  This 36K remainder is not packed into a fragment by default.  This
+is because to do so leads to a 10 - 20% drop in sequential I/O performance, as a
+disk head seek is needed to seek to the initial file data and another disk seek
+is need to seek to the fragment block.  Specify this option if you want file
+remainders to be packed into fragment blocks.  Doing so may increase the
+compression obtained BUT at the expense of I/O speed.
+
+The -no-duplicates option tells mksquashfs to not check the files being
+added to the filesystem for duplicates.  This can result in quicker filesystem
+generation and appending although obviously compression will suffer badly if
+there is a lot of duplicate files.
+
+The -b option allows the block size to be selected, both "K" and "M" postfixes
+are supported, this can be either 4K, 8K, 16K, 32K, 64K, 128K, 256K, 512K or
+1M bytes.
+
+3.4 Specifying the UIDs/GIDs used in the filesystem
+---------------------------------------------------
+
+By default files in the generated filesystem inherit the UID and GID ownership
+of the original file.  However,  mksquashfs provides a number of options which
+can be used to override the ownership.
+
+The options -all-root and -root-owned (both do exactly the same thing) force all
+file uids/gids in the generated Squashfs filesystem to be root.  This allows
+root owned filesystems to be built without root access on the host machine.
+
+The "-force-uid uid"  option forces all files in the generated Squashfs
+filesystem to be owned by the specified uid.  The uid can be specified either by
+name (i.e. "root") or by number.
+
+The "-force-gid gid" option forces all files in the generated Squashfs
+filesystem to be group owned by the specified gid.  The gid can be specified
+either by name (i.e. "root") or by number.
+
+3.5 Excluding files from the filesystem
+---------------------------------------
+
+The -e and -ef options allow files/directories to be specified which are
+excluded from the output filesystem.  The -e option takes the exclude
+files/directories from the command line, the -ef option takes the
+exlude files/directories from the specified exclude file, one file/directory
+per line.
+
+Two styles of exclude file matching are supported: basic exclude matching, and
+extended wildcard matching.  Basic exclude matching is a legacy feature
+retained for backwards compatibility with earlier versions of Mksquashfs.
+Extended wildcard matching should be used in preference.
+
+3.5.1 Basic exclude matching
+----------------------------
+
+Each exclude file is treated as an exact match of a file/directory in
+the source directories.  If an exclude file/directory is absolute (i.e.
+prefixed with /, ../, or ./) the entry is treated as absolute, however, if an
+exclude file/directory is relative, it is treated as being relative to each of
+the sources in turn, i.e.
+
+%mksquashfs /tmp/source1 source2  output_fs -e ex1 /tmp/source1/ex2 out/ex3
+
+Will generate exclude files /tmp/source1/ex2, /tmp/source1/ex1, source2/ex1,
+/tmp/source1/out/ex3 and source2/out/ex3.
+
+3.5.2 Extended exclude file handling
+------------------------------------
+
+Extended exclude file matching treats each exclude file as a wildcard or
+regex expression.  To enable wildcard matching specify the -wildcards
+option, and to enable regex matching specify the -regex option.  In most
+cases the -wildcards option should be used rather than -regex because wildcard
+matching behaviour is significantly easier to understand!
+
+In addition to wildcards/regex expressions, exclude files can be "anchored" or
+"non-anchored".  An anchored exclude is one which matches from the root of the
+directory and nowhere else, a non-anchored exclude matches anywhere.  For
+example given the directory hierarchy "a/b/c/a/b", the anchored exclude
+"a/b" will match "a/b" at the root of the directory hierarchy, but
+it will not match the "/a/b" sub-directory within directory "c", whereas a
+non-anchored exclude would.
+
+A couple of examples should make this clearer.
+ 
+Anchored excludes
+
+  1. mksquashfs example image.sqsh -wildcards -e 'test/*.gz'
+
+     Exclude all files matching "*.gz" in the top level directory "test".
+
+  2. mksquashfs example image.sqsh -wildcards -e '*/[Tt]est/example*'
+
+     Exclude all files beginning with "example" inside directories called
+     "Test" or "test", that occur inside any top level directory.
+
+  Using extended wildcards, negative matching is also possible.
+
+  3. mksquashfs example image.sqsh -wildcards -e 'test/!(*data*).gz'
+
+     Exclude all files matching "*.gz" in top level directory "test",
+     except those with "data" in the name.
+
+Non-anchored excludes
+
+  By default excludes match from the top level directory, but it is
+  often useful to exclude a file matching anywhere in the source directories.
+  For this non-anchored excludes can be used, specified by pre-fixing the
+  exclude with "...".
+
+  Examples:
+
+  1. mksquashfs example image.sqsh -wildcards -e '... *.gz'
+
+     Exclude files matching "*.gz" anywhere in the source directories.
+     For example this will match "example.gz", "test/example.gz", and
+     "test/test/example.gz".
+
+  2. mksquashfs example image.sqsh -wildcards -e '... [Tt]est/*.gz'
+
+     Exclude files matching "*.gz" inside directories called "Test" or
+     "test" that occur anywhere in the source directories.
+
+  Again, using extended wildcards, negative matching is also possible.
+
+  3. mksquashfs example image.sqsh -wildcards -e '... !(*data*).gz'
+
+     Exclude all files matching "*.gz" anywhere in the source directories,
+     except those with "data" in the name.
+
+3.5.3 Exclude files summary
+---------------------------
+
+The -e and -ef exclude options are usefully used in archiving the entire
+filesystem, where it is wished to avoid archiving /proc, and the filesystem
+being generated, i.e.
+
+%mksquashfs / /tmp/root.sqsh -e proc /tmp/root.sqsh
+
+Multiple -ef options can be specified on the command line, and the -ef
+option can be used in conjuction with the -e option.
+
+3.6 Appending to squashfs filesystems
+-------------------------------------
+
+Running squashfs with the destination directory containing an existing
+filesystem will add the source items to the existing filesystem.  By default,
+the source items are added to the existing root directory.
+
+To make this clear... An existing filesystem "image" contains root entries
+"old1", and "old2".  Source directory "/home/phillip/test" contains  "file1",
+"file2" and "dir1".
+
+example 1:
+
+%mksquashfs /home/phillip/test image
+
+Will create a new "image" with root entries "old1", "old2", "file1", "file2" and
+"dir1"
+
+example 2:
+
+%mksquashfs /home/phillip/test image -keep-as-directory
+
+Will create a new "image" with root entries "old1", "old2", and "test".
+As shown in the previous section, for single source directories
+'-keep-as-directory' adds the source directory rather than the
+contents of the directory.
+
+example 3:
+
+%mksquashfs /home/phillip/test image -keep-as-directory -root-becomes
+original-root
+
+Will create a new "image" with root entries "original-root", and "test".  The
+'-root-becomes' option specifies that the original root becomes a subdirectory
+in the new root, with the specified name.
+
+The append option with file duplicate detection, means squashfs can be
+used as a simple versioning archiving filesystem. A squashfs filesystem can
+be created with for example the linux-2.4.19 source.  Appending the linux-2.4.20
+source will create a filesystem with the two source trees, but only the
+changed files will take extra room, the unchanged files will be detected as
+duplicates.
+
+3.7 Appending recovery file feature
+-----------------------------------
+
+Recovery files are created when appending to existing Squashfs
+filesystems.  This allows the original filesystem to be recovered
+if Mksquashfs aborts unexpectedly (i.e. power failure).
+
+The recovery files are called squashfs_recovery_xxx_yyy, where
+"xxx" is the name of the filesystem being appended to, and "yyy" is a
+number to guarantee filename uniqueness (the PID of the parent Mksquashfs
+process).
+
+Normally if Mksquashfs exits correctly the recovery file is deleted to
+avoid cluttering the filesystem.  If Mksquashfs aborts, the "-recover"
+option can be used to recover the filesystem, giving the previously
+created recovery file as a parameter, i.e.
+
+mksquashfs dummy image.sqsh -recover squashfs_recovery_image.sqsh_1234
+
+The writing of the recovery file can be disabled by specifying the
+"-no-recovery" option.
+
+3.8 Pseudo file support
+-----------------------
+
+Mksquashfs supports pseudo files, these allow fake files, directories, character
+and block devices to be specified and added to the Squashfs filesystem being
+built, rather than requiring them to be present in the source directories.
+This, for example, allows device nodes to be added to the filesystem without
+requiring root access.
+
+Mksquashfs 4.1 added support for "dynamic pseudo files" and a modify operation.
+Dynamic pseudo files allow files to be dynamically created when Mksquashfs
+is run, their contents being the result of running a command or piece of
+shell script.  The modifiy operation allows the mode/uid/gid of an existing
+file in the source filesystem to be modified.
+
+Mksquashfs 4.4 adds support for Symbolic links.
+
+Two Mksquashfs options are supported, -p allows one pseudo file to be specified
+on the command line, and -pf allows a pseudo file to be specified containing a
+list of pseduo definitions, one per line.
+
+3.8.1. Creating a dynamic file
+------------------------------
+
+Pseudo definition
+
+Filename f mode uid gid command
+
+mode is the octal mode specifier, similar to that expected by chmod.
+
+uid and gid can be either specified as a decimal number, or by name.
+
+command can be an executable or a piece of shell script, and it is executed
+by running "/bin/sh -c command".   The stdout becomes the contents of
+"Filename".
+
+Examples:
+
+Running a basic command
+-----------------------
+
+/somedir/dmesg f 444 root root dmesg
+
+creates a file "/somedir/dmesg" containing the output from dmesg.
+
+Executing shell script
+----------------------
+
+RELEASE f 444 root root \
+		if [ ! -e /tmp/ver ]; then \
+			echo 0 > /tmp/ver; \
+		fi; \
+                ver=`cat /tmp/ver`; \
+                ver=$((ver +1)); \
+                echo $ver > /tmp/ver; \
+                echo -n `cat /tmp/release`; \
+                echo "-dev #"$ver `date` "Build host" `hostname`
+
+Creates a file RELEASE containing the release name, date, build host, and
+an incrementing version number.  The incrementing version is a side-effect
+of executing the shell script, and ensures every time Mksquashfs is run a
+new version number is used without requiring any other shell scripting.
+
+The above example also shows that commands can be split across multiple lines
+using "\".  Obviously as the script will be presented to the shell as a single
+line, a semicolon is need to separate individual shell commands within the
+shell script.
+
+Reading from a device (or fifo/named socket)
+--------------------------------------------
+
+input f 444 root root dd if=/dev/sda1 bs=1024 count=10
+
+Copies 10K from the device /dev/sda1 into the file input.  Ordinarily Mksquashfs
+given a device, fifo, or named socket will place that special file within the
+Squashfs filesystem, the above allows input from these special files to be
+captured and placed in the Squashfs filesystem.
+
+3.8.2. Creating a block or character device
+-------------------------------------------
+
+Pseudo definition
+
+Filename type mode uid gid major minor
+
+Where type is either
+	b - for block devices, and
+	c - for character devices
+
+mode is the octal mode specifier, similar to that expected by chmod.
+
+uid and gid can be either specified as a decimal number, or by name.
+
+For example:
+
+/dev/chr_dev c 666 root root 100 1
+/dev/blk_dev b 666 0 0 200 200
+
+creates a character device "/dev/chr_dev" with major:minor 100:1 and
+a block device "/dev/blk_dev" with major:minor 200:200, both with root
+uid/gid and a mode of rw-rw-rw.
+
+3.8.3. Creating a directory
+---------------------------
+
+Pseudo definition
+
+Filename d mode uid gid
+
+mode is the octal mode specifier, similar to that expected by chmod.
+
+uid and gid can be either specified as a decimal number, or by name.
+
+For example:
+
+/pseudo_dir d 666 root root
+
+creates a directory "/pseudo_dir" with root uid/gid and mode of rw-rw-rw.
+
+3.8.4. Creating a symbolic link
+-------------------------------
+
+Pseudo definition
+
+Filename s mode uid gid symlink
+
+uid and gid can be either specified as a decimal number, or by name.
+
+Note mode is ignored, as symlinks always have "rwxrwxrwx" permissions.
+
+For example:
+
+symlink s 0 root root example
+
+creates a symlink "symlink" to file "example" with root uid/gid.
+
+3.8.5. Modifying attributes of an existing file
+-----------------------------------------------
+
+Pseudo definition
+
+Filename m mode uid gid
+
+mode is the octal mode specifier, similar to that expected by chmod.
+
+uid and gid can be either specified as a decimal number, or by name.
+
+For example:
+
+dmesg m 666 root root
+
+Changes the attributes of the file "dmesg" in the filesystem to have
+root uid/gid and a mode of rw-rw-rw, overriding the attributes obtained
+from the source filesystem.
+
+3.9 Miscellaneous options
+-------------------------
+
+The -info option displays the files/directories as they are compressed and
+added to the filesystem.  The original uncompressed size of each file
+is printed, along with DUPLICATE if the file is a duplicate of a
+file in the filesystem.
+
+The -nopad option informs mksquashfs to not pad the filesystem to a 4K multiple.
+This is performed by default to enable the output filesystem file to be mounted
+by loopback, which requires files to be a 4K multiple.  If the filesystem is
+being written to a block device, or is to be stored in a bootimage, the extra
+pad bytes are not needed.
+
+4. UNSQUASHFS
+-------------
+
+Unsquashfs allows you to decompress and extract a Squashfs filesystem without
+mounting it.  It can extract the entire filesystem, or a specific
+file or directory.
+
+Unsquashfs can decompress all official Squashfs filesystem versions.
+
+The Unsquashfs usage info is:
+
+SYNTAX: unsquashfs [options] filesystem [directories or files to extract]
+	-v[ersion]		print version, licence and copyright information
+	-d[est] <pathname>	unsquash to <pathname>, default "squashfs-root"
+	-q[uiet]		no verbose output
+	-n[o-progress]		don't display the progress bar
+	-no[-xattrs]		don't extract xattrs in file system
+	-x[attrs]		extract xattrs in file system (default)
+	-u[ser-xattrs]		only extract user xattrs in file system.
+				Enables extracting xattrs
+	-p[rocessors] <number>	use <number> processors.  By default will use
+				number of processors available
+	-i[nfo]			print files as they are unsquashed
+	-li[nfo]		print files as they are unsquashed with file
+				attributes (like ls -l output)
+	-l[s]			list filesystem, but don't unsquash
+	-ll[s]			list filesystem with file attributes (like
+				ls -l output), but don't unsquash
+	-lln[umeric]		-lls but with numeric uids and gids
+	-lc			list filesystem concisely, displaying only files
+				and empty directories.  Don't unsquash
+	-llc			list filesystem concisely with file attributes,
+				displaying only files and empty directories.
+				Don't unsquash
+	-o[ffset] <bytes>	skip <bytes> at start of <dest>
+				Optionally a suffix of K, M or G can be given to specify
+				Kbytes, Mbytes or Gbytes respectively.
+				Default 0 bytes.
+	-f[orce]		if file already exists then overwrite
+	-ig[nore-errors]	Treat errors writing files to output as non-fatal
+	-st[rict-errors]	Treat all errors as fatal
+	-s[tat]			display filesystem superblock information
+	-UTC			Use UTC rather than local time zone when displaying time
+	-mkfs-time		display filesystem superblock time
+	-fstime			synonym for -mkfs-time
+	-e[f] <extract file>	list of directories or files to extract.
+				One per line
+	-da[ta-queue] <size>	Set data queue to <size> Mbytes.  Default 256
+				Mbytes
+	-fr[ag-queue] <size>	Set fragment queue to <size> Mbytes.  Default
+				256 Mbytes
+	-r[egex]		treat extract names as POSIX regular expressions
+				rather than use the default shell wildcard
+				expansion (globbing)
+
+Decompressors available:
+	gzip
+	lzo
+	lz4
+	xz
+	zstd
+
+To extract a subset of the filesystem, the filenames or directory
+trees that are to be extracted can be specified on the command line.  The
+files/directories should be specified using the full path to the
+files/directories as they appear within the Squashfs filesystem.  The
+files/directories will also be extracted to those positions within the specified
+destination directory.
+
+The extract files can also be given in a file using the "-e[f]" option.
+
+Similarly to Mksquashfs, wildcard matching is performed on the extract
+files.  Wildcard matching is enabled by default.
+
+Examples:
+
+  1. unsquashfs image.sqsh 'test/*.gz'
+
+     Extract all files matching "*.gz" in the top level directory "test".
+
+  2. unsquashfs image.sqsh '[Tt]est/example*'
+
+     Extract all files beginning with "example" inside top level directories
+     called "Test" or "test".
+
+  Using extended wildcards, negative matching is also possible.
+
+  3. unsquashfs image.sqsh 'test/!(*data*).gz'
+
+     Extract all files matching "*.gz" in top level directory "test",
+     except those with "data" in the name.
+
+
+4.1 Unsquashfs options
+----------------------
+
+The "-ls" option can be used to list the contents of a filesystem without
+decompressing the filesystem data itself.  The "-lls" option is similar
+but it also displays file attributes (ls -l style output).  The "-lln"
+option is the same but displays uids and gids numerically.
+
+The "-lc" option is similar to the -ls option except it only displays files
+and empty directories.  The -llc option displays file attributes.
+
+The "-info" option forces Unsquashfs to print each file as it is decompressed.
+The -"linfo" is similar but it also displays file attributes.
+
+The "-dest" option specifies the directory that is used to decompress
+the filesystem data.  If this option is not given then the filesystem is
+decompressed to the directory "squashfs-root" in the current working directory.
+
+The "-force" option forces Unsquashfs to output to the destination
+directory even if files or directories already exist.  This allows you
+to update an existing directory tree, or to Unsquashfs to a partially
+filled directory.  Without the "-force" option, Unsquashfs will
+refuse to overwrite any existing files, or to create any directories if they
+already exist.  This is done to protect data in case of mistakes, and
+so the "-force" option should be used with caution.
+
+The "-stat" option displays filesystem superblock information.  This is
+useful to discover the filesystem version, byte ordering, whether it has a NFS
+export table, and what options were used to compress the filesystem, etc.
+
+The -mkfs-time option displays the make filesystem time contained
+in the super-block.  This is displayed as the number of seconds since
+the epoch of 1970-01-01 00:00:00 UTC.
+
+The -UTC option makes Unsquashfs display all times in the UTC time zone
+rather than using the default local time zone.
+
+4.2. Dealing with errors
+------------------------
+
+Unsquashfs splits errors into two categories: fatal errors and non-fatal
+errors.
+
+Fatal errors are those which cause Unsquashfs to abort instantly.
+These are generally due to failure to read the filesystem (corruption),
+and/or failure to write files to the output filesystem, due to I/O error
+or out of space.  Generally anything which is unexpected is a fatal error.
+
+Non-fatal errors are generally where support is lacking in the
+output filesystem, and it can be considered to be an expected failure.
+This includes the inability to write extended attributes (xattrs) to
+a filesystem that doesn't support them, the inability to create files on
+filesystem that doesn't support them (i.e. symbolic links on VFAT), and the
+inability to execute privileged operations as a user-process.
+
+The user may well know the filesystem cannot support certain operations
+and would prefer Unsquashfs to ignore then without aborting.
+
+In the past Unsquashfs was much more tolerant of errors, in this
+release a significant number of errors that were non-fatal have been
+hardened to fatal.
+
+4.2.1. -ignore-errors
+
+This makes Unsquashfs behave like previous versions, and treats more
+errors as non-fatal.
+
+4.2.2 -strict-errors
+
+This makes Unsquashfs treat every error as fatal, and it will abort
+instantly.
+
+5. FILESYSTEM LAYOUT
+--------------------
+
+A squashfs filesystem consists of a maximum of nine parts, packed together on a
+byte alignment:
+
+	 ---------------
+	|  superblock 	|
+	|---------------|
+	|  compression  |
+	|    options    |
+	|---------------|
+	|  datablocks   |
+	|  & fragments  |
+	|---------------|
+	|  inode table	|
+	|---------------|
+	|   directory	|
+	|     table     |
+	|---------------|
+	|   fragment	|
+	|    table      |
+	|---------------|
+	|    export     |
+	|    table      |
+	|---------------|
+	|    uid/gid	|
+	|  lookup table	|
+	|---------------|
+	|     xattr     |
+	|     table	|
+	 ---------------
+
+Compressed data blocks are written to the filesystem as files are read from
+the source directory, and checked for duplicates.  Once all file data has been
+written the completed super-block, compression options, inode, directory,
+fragment, export, uid/gid lookup and xattr tables are written.
+
+5.1 Compression options
+-----------------------
+
+Compressors can optionally support compression specific options (e.g.
+dictionary size).  If non-default compression options have been used, then
+these are stored here.
+
+5.2 Inodes
+----------
+
+Metadata (inodes and directories) are compressed in 8Kbyte blocks.  Each
+compressed block is prefixed by a two byte length, the top bit is set if the
+block is uncompressed.  A block will be uncompressed if the -noI option is set,
+or if the compressed block was larger than the uncompressed block.
+
+Inodes are packed into the metadata blocks, and are not aligned to block
+boundaries, therefore inodes overlap compressed blocks.  Inodes are identified
+by a 48-bit number which encodes the location of the compressed metadata block
+containing the inode, and the byte offset into that block where the inode is
+placed (<block, offset>).
+
+To maximise compression there are different inodes for each file type
+(regular file, directory, device, etc.), the inode contents and length
+varying with the type.
+
+To further maximise compression, two types of regular file inode and
+directory inode are defined: inodes optimised for frequently occurring
+regular files and directories, and extended types where extra
+information has to be stored.
+
+5.3 Directories
+---------------
+
+Like inodes, directories are packed into compressed metadata blocks, stored
+in a directory table.  Directories are accessed using the start address of
+the metablock containing the directory and the offset into the
+decompressed block (<block, offset>).
+
+Directories are organised in a slightly complex way, and are not simply
+a list of file names.  The organisation takes advantage of the
+fact that (in most cases) the inodes of the files will be in the same
+compressed metadata block, and therefore, can share the start block.
+Directories are therefore organised in a two level list, a directory
+header containing the shared start block value, and a sequence of directory
+entries, each of which share the shared start block.  A new directory header
+is written once/if the inode start block changes.  The directory
+header/directory entry list is repeated as many times as necessary.
+
+Directories are sorted, and can contain a directory index to speed up
+file lookup.  Directory indexes store one entry per metablock, each entry
+storing the index/filename mapping to the first directory header
+in each metadata block.  Directories are sorted in alphabetical order,
+and at lookup the index is scanned linearly looking for the first filename
+alphabetically larger than the filename being looked up.  At this point the
+location of the metadata block the filename is in has been found.
+The general idea of the index is ensure only one metadata block needs to be
+decompressed to do a lookup irrespective of the length of the directory.
+This scheme has the advantage that it doesn't require extra memory overhead
+and doesn't require much extra storage on disk.
+
+5.4 File data
+-------------
+
+Regular files consist of a sequence of contiguous compressed blocks, and/or a
+compressed fragment block (tail-end packed block).   The compressed size
+of each datablock is stored in a block list contained within the
+file inode.
+
+To speed up access to datablocks when reading 'large' files (256 Mbytes or
+larger), the code implements an index cache that caches the mapping from
+block index to datablock location on disk.
+
+The index cache allows Squashfs to handle large files (up to 1.75 TiB) while
+retaining a simple and space-efficient block list on disk.  The cache
+is split into slots, caching up to eight 224 GiB files (128 KiB blocks).
+Larger files use multiple slots, with 1.75 TiB files using all 8 slots.
+The index cache is designed to be memory efficient, and by default uses
+16 KiB.
+
+5.5 Fragment lookup table
+-------------------------
+
+Regular files can contain a fragment index which is mapped to a fragment
+location on disk and compressed size using a fragment lookup table.  This
+fragment lookup table is itself stored compressed into metadata blocks.
+A second index table is used to locate these.  This second index table for
+speed of access (and because it is small) is read at mount time and cached
+in memory.
+
+5.6 Uid/gid lookup table
+------------------------
+
+For space efficiency regular files store uid and gid indexes, which are
+converted to 32-bit uids/gids using an id look up table.  This table is
+stored compressed into metadata blocks.  A second index table is used to
+locate these.  This second index table for speed of access (and because it
+is small) is read at mount time and cached in memory.
+
+5.7 Export table
+----------------
+
+To enable Squashfs filesystems to be exportable (via NFS etc.) filesystems
+can optionally (disabled with the -no-exports Mksquashfs option) contain
+an inode number to inode disk location lookup table.  This is required to
+enable Squashfs to map inode numbers passed in filehandles to the inode
+location on disk, which is necessary when the export code reinstantiates
+expired/flushed inodes.
+
+This table is stored compressed into metadata blocks.  A second index table is
+used to locate these.  This second index table for speed of access (and because
+it is small) is read at mount time and cached in memory.
+
+5.8 Xattr table
+---------------
+
+The xattr table contains extended attributes for each inode.  The xattrs
+for each inode are stored in a list, each list entry containing a type,
+name and value field.  The type field encodes the xattr prefix
+("user.", "trusted." etc) and it also encodes how the name/value fields
+should be interpreted.  Currently the type indicates whether the value
+is stored inline (in which case the value field contains the xattr value),
+or if it is stored out of line (in which case the value field stores a
+reference to where the actual value is stored).  This allows large values
+to be stored out of line improving scanning and lookup performance and it
+also allows values to be de-duplicated, the value being stored once, and
+all other occurences holding an out of line reference to that value.
+
+The xattr lists are packed into compressed 8K metadata blocks.
+To reduce overhead in inodes, rather than storing the on-disk
+location of the xattr list inside each inode, a 32-bit xattr id
+is stored.  This xattr id is mapped into the location of the xattr
+list using a second xattr id lookup table.
+
+6. AUTHOR INFO
+--------------
+
+Squashfs was written by Phillip Lougher, email phillip@squashfs.org.uk,
+in Chepstow, Wales, UK.   If you like the program, or have any problems,
+then please email me, as it's nice to get feedback!

SQUASHFS/squashfs-tools-4.4/kernel/README

+Squashfs is now in mainline at www.kernel.org.
+
+These files are obsolete and not updated.

SQUASHFS/squashfs-tools-4.4/kernel/kernel-2.4/fs/squashfs/Makefile

+#
+# Makefile for the linux squashfs routines.
+#
+
+O_TARGET := squashfs.o
+
+obj-y  := inode.o squashfs2_0.o
+
+obj-m := $(O_TARGET)
+
+include $(TOPDIR)/Rules.make

SQUASHFS/squashfs-tools-4.4/kernel/kernel-2.4/fs/squashfs/inode.c

+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2002, 2003, 2004, 2005, 2006
+ * Phillip Lougher <phillip@lougher.demon.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2,
+ * or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * inode.c
+ */
+
+#include <linux/types.h>
+#include <linux/squashfs_fs.h>
+#include <linux/module.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/zlib.h>
+#include <linux/fs.h>
+#include <linux/smp_lock.h>
+#include <linux/locks.h>
+#include <linux/init.h>
+#include <linux/dcache.h>
+#include <linux/wait.h>
+#include <linux/blkdev.h>
+#include <linux/vmalloc.h>
+#include <asm/uaccess.h>
+#include <asm/semaphore.h>
+
+#include "squashfs.h"
+
+static struct super_block *squashfs_read_super(struct super_block *, void *, int);
+static void squashfs_put_super(struct super_block *);
+static int squashfs_statfs(struct super_block *, struct statfs *);
+static int squashfs_symlink_readpage(struct file *file, struct page *page);
+static int squashfs_readpage(struct file *file, struct page *page);
+static int squashfs_readpage4K(struct file *file, struct page *page);
+static int squashfs_readdir(struct file *, void *, filldir_t);
+static struct dentry *squashfs_lookup(struct inode *, struct dentry *);
+static struct inode *squashfs_iget(struct super_block *s, squashfs_inode_t inode);
+static long long read_blocklist(struct inode *inode, int index,
+				int readahead_blks, char *block_list,
+				unsigned short **block_p, unsigned int *bsize);
+
+static DECLARE_FSTYPE_DEV(squashfs_fs_type, "squashfs", squashfs_read_super);
+
+static unsigned char squashfs_filetype_table[] = {
+	DT_UNKNOWN, DT_DIR, DT_REG, DT_LNK, DT_BLK, DT_CHR, DT_FIFO, DT_SOCK
+};
+
+static struct super_operations squashfs_ops = {
+	.statfs = squashfs_statfs,
+	.put_super = squashfs_put_super,
+};
+
+SQSH_EXTERN struct address_space_operations squashfs_symlink_aops = {
+	.readpage = squashfs_symlink_readpage
+};
+
+SQSH_EXTERN struct address_space_operations squashfs_aops = {
+	.readpage = squashfs_readpage
+};
+
+SQSH_EXTERN struct address_space_operations squashfs_aops_4K = {
+	.readpage = squashfs_readpage4K
+};
+
+static struct file_operations squashfs_dir_ops = {
+	.read = generic_read_dir,
+	.readdir = squashfs_readdir
+};
+
+static struct inode_operations squashfs_dir_inode_ops = {
+	.lookup = squashfs_lookup
+};
+
+static struct buffer_head *get_block_length(struct super_block *s,
+				int *cur_index, int *offset, int *c_byte)
+{
+	struct squashfs_sb_info *msblk = &s->u.squashfs_sb;
+	unsigned short temp;
+	struct buffer_head *bh;
+
+	if (!(bh = sb_bread(s, *cur_index)))
+		goto out;
+
+	if (msblk->devblksize - *offset == 1) {
+		if (msblk->swap)
+			((unsigned char *) &temp)[1] = *((unsigned char *)
+				(bh->b_data + *offset));
+		else
+			((unsigned char *) &temp)[0] = *((unsigned char *)
+				(bh->b_data + *offset));
+		brelse(bh);
+		if (!(bh = sb_bread(s, ++(*cur_index))))
+			goto out;
+		if (msblk->swap)
+			((unsigned char *) &temp)[0] = *((unsigned char *)
+				bh->b_data); 
+		else
+			((unsigned char *) &temp)[1] = *((unsigned char *)
+				bh->b_data); 
+		*c_byte = temp;
+		*offset = 1;
+	} else {
+		if (msblk->swap) {
+			((unsigned char *) &temp)[1] = *((unsigned char *)
+				(bh->b_data + *offset));
+			((unsigned char *) &temp)[0] = *((unsigned char *)
+				(bh->b_data + *offset + 1)); 
+		} else {
+			((unsigned char *) &temp)[0] = *((unsigned char *)
+				(bh->b_data + *offset));
+			((unsigned char *) &temp)[1] = *((unsigned char *)
+				(bh->b_data + *offset + 1)); 
+		}
+		*c_byte = temp;
+		*offset += 2;
+	}
+
+	if (SQUASHFS_CHECK_DATA(msblk->sblk.flags)) {
+		if (*offset == msblk->devblksize) {
+			brelse(bh);
+			if (!(bh = sb_bread(s, ++(*cur_index))))
+				goto out;
+			*offset = 0;
+		}
+		if (*((unsigned char *) (bh->b_data + *offset)) !=
+						SQUASHFS_MARKER_BYTE) {
+			ERROR("Metadata block marker corrupt @ %x\n",
+						*cur_index);
+			brelse(bh);
+			goto out;
+		}
+		(*offset)++;
+	}
+	return bh;
+
+out:
+	return NULL;
+}
+
+
+SQSH_EXTERN unsigned int squashfs_read_data(struct super_block *s, char *buffer,
+			long long index, unsigned int length,
+			long long *next_index)
+{
+	struct squashfs_sb_info *msblk = &s->u.squashfs_sb;
+	struct buffer_head *bh[((SQUASHFS_FILE_MAX_SIZE - 1) >>
+			msblk->devblksize_log2) + 2];
+	unsigned int offset = index & ((1 << msblk->devblksize_log2) - 1);
+	unsigned int cur_index = index >> msblk->devblksize_log2;
+	int bytes, avail_bytes, b = 0, k;
+	char *c_buffer;
+	unsigned int compressed;
+	unsigned int c_byte = length;
+
+	if (c_byte) {
+		bytes = msblk->devblksize - offset;
+		compressed = SQUASHFS_COMPRESSED_BLOCK(c_byte);
+		c_buffer = compressed ? msblk->read_data : buffer;
+		c_byte = SQUASHFS_COMPRESSED_SIZE_BLOCK(c_byte);
+
+		TRACE("Block @ 0x%llx, %scompressed size %d\n", index, compressed
+					? "" : "un", (unsigned int) c_byte);
+
+		if (!(bh[0] = sb_getblk(s, cur_index)))
+			goto block_release;
+
+		for (b = 1; bytes < c_byte; b++) {
+			if (!(bh[b] = sb_getblk(s, ++cur_index)))
+				goto block_release;
+			bytes += msblk->devblksize;
+		}
+		ll_rw_block(READ, b, bh);
+	} else {
+		if (!(bh[0] = get_block_length(s, &cur_index, &offset,
+								&c_byte)))
+			goto read_failure;
+
+		bytes = msblk->devblksize - offset;
+		compressed = SQUASHFS_COMPRESSED(c_byte);
+		c_buffer = compressed ? msblk->read_data : buffer;
+		c_byte = SQUASHFS_COMPRESSED_SIZE(c_byte);
+
+		TRACE("Block @ 0x%llx, %scompressed size %d\n", index, compressed
+					? "" : "un", (unsigned int) c_byte);
+
+		for (b = 1; bytes < c_byte; b++) {
+			if (!(bh[b] = sb_getblk(s, ++cur_index)))
+				goto block_release;
+			bytes += msblk->devblksize;
+		}
+		ll_rw_block(READ, b - 1, bh + 1);
+	}
+
+	if (compressed)
+		down(&msblk->read_data_mutex);
+
+	for (bytes = 0, k = 0; k < b; k++) {
+		avail_bytes = (c_byte - bytes) > (msblk->devblksize - offset) ?
+					msblk->devblksize - offset :
+					c_byte - bytes;
+		wait_on_buffer(bh[k]);
+		if (!buffer_uptodate(bh[k]))
+			goto block_release;
+		memcpy(c_buffer + bytes, bh[k]->b_data + offset, avail_bytes);
+		bytes += avail_bytes;
+		offset = 0;
+		brelse(bh[k]);
+	}
+
+	/*
+	 * uncompress block
+	 */
+	if (compressed) {
+		int zlib_err;
+
+		msblk->stream.next_in = c_buffer;
+		msblk->stream.avail_in = c_byte;
+		msblk->stream.next_out = buffer;
+		msblk->stream.avail_out = msblk->read_size;
+
+		if (((zlib_err = zlib_inflateInit(&msblk->stream)) != Z_OK) ||
+				((zlib_err = zlib_inflate(&msblk->stream, Z_FINISH))
+				 != Z_STREAM_END) || ((zlib_err =
+				zlib_inflateEnd(&msblk->stream)) != Z_OK)) {
+			ERROR("zlib_fs returned unexpected result 0x%x\n",
+				zlib_err);
+			bytes = 0;
+		} else
+			bytes = msblk->stream.total_out;
+		
+		up(&msblk->read_data_mutex);
+	}
+
+	if (next_index)
+		*next_index = index + c_byte + (length ? 0 :
+				(SQUASHFS_CHECK_DATA(msblk->sblk.flags)
+				 ? 3 : 2));
+	return bytes;
+
+block_release:
+	while (--b >= 0)
+		brelse(bh[b]);
+
+read_failure:
+	ERROR("sb_bread failed reading block 0x%x\n", cur_index);
+	return 0;
+}
+
+
+SQSH_EXTERN int squashfs_get_cached_block(struct super_block *s, char *buffer,
+				long long block, unsigned int offset,
+				int length, long long *next_block,
+				unsigned int *next_offset)
+{
+	struct squashfs_sb_info *msblk = &s->u.squashfs_sb;
+	int n, i, bytes, return_length = length;
+	long long next_index;
+
+	TRACE("Entered squashfs_get_cached_block [%llx:%x]\n", block, offset);
+
+	while ( 1 ) {
+		for (i = 0; i < SQUASHFS_CACHED_BLKS; i++) 
+			if (msblk->block_cache[i].block == block)
+				break; 
+		
+		down(&msblk->block_cache_mutex);
+
+		if (i == SQUASHFS_CACHED_BLKS) {
+			/* read inode header block */
+			for (i = msblk->next_cache, n = SQUASHFS_CACHED_BLKS;
+					n ; n --, i = (i + 1) %
+					SQUASHFS_CACHED_BLKS)
+				if (msblk->block_cache[i].block !=
+							SQUASHFS_USED_BLK)
+					break;
+
+			if (n == 0) {
+				wait_queue_t wait;
+
+				init_waitqueue_entry(&wait, current);
+				add_wait_queue(&msblk->waitq, &wait);
+				set_current_state(TASK_UNINTERRUPTIBLE);
+ 				up(&msblk->block_cache_mutex);
+				schedule();
+				set_current_state(TASK_RUNNING);
+				remove_wait_queue(&msblk->waitq, &wait);
+				continue;
+			}
+			msblk->next_cache = (i + 1) % SQUASHFS_CACHED_BLKS;
+
+			if (msblk->block_cache[i].block ==
+							SQUASHFS_INVALID_BLK) {
+				if (!(msblk->block_cache[i].data =
+						kmalloc(SQUASHFS_METADATA_SIZE,
+						GFP_KERNEL))) {
+					ERROR("Failed to allocate cache"
+							"block\n");
+					up(&msblk->block_cache_mutex);
+					goto out;
+				}
+			}
+	
+			msblk->block_cache[i].block = SQUASHFS_USED_BLK;
+			up(&msblk->block_cache_mutex);
+
+			if (!(msblk->block_cache[i].length =
+						squashfs_read_data(s,
+						msblk->block_cache[i].data,
+						block, 0, &next_index))) {
+				ERROR("Unable to read cache block [%llx:%x]\n",
+						block, offset);
+				goto out;
+			}
+
+			down(&msblk->block_cache_mutex);
+			wake_up(&msblk->waitq);
+			msblk->block_cache[i].block = block;
+			msblk->block_cache[i].next_index = next_index;
+			TRACE("Read cache block [%llx:%x]\n", block, offset);
+		}
+
+		if (msblk->block_cache[i].block != block) {
+			up(&msblk->block_cache_mutex);
+			continue;
+		}
+
+		if ((bytes = msblk->block_cache[i].length - offset) >= length) {
+			if (buffer)
+				memcpy(buffer, msblk->block_cache[i].data +
+						offset, length);
+			if (msblk->block_cache[i].length - offset == length) {
+				*next_block = msblk->block_cache[i].next_index;
+				*next_offset = 0;
+			} else {
+				*next_block = block;
+				*next_offset = offset + length;
+			}
+			up(&msblk->block_cache_mutex);
+			goto finish;
+		} else {
+			if (buffer) {
+				memcpy(buffer, msblk->block_cache[i].data +
+						offset, bytes);
+				buffer += bytes;
+			}
+			block = msblk->block_cache[i].next_index;
+			up(&msblk->block_cache_mutex);
+			length -= bytes;
+			offset = 0;
+		}
+	}
+
+finish:
+	return return_length;
+out:
+	return 0;
+}
+
+
+static int get_fragment_location(struct super_block *s, unsigned int fragment,
+				long long *fragment_start_block,
+				unsigned int *fragment_size)
+{
+	struct squashfs_sb_info *msblk = &s->u.squashfs_sb;
+	long long start_block =
+		msblk->fragment_index[SQUASHFS_FRAGMENT_INDEX(fragment)];
+	int offset = SQUASHFS_FRAGMENT_INDEX_OFFSET(fragment);
+	struct squashfs_fragment_entry fragment_entry;
+
+	if (msblk->swap) {
+		struct squashfs_fragment_entry sfragment_entry;
+
+		if (!squashfs_get_cached_block(s, (char *) &sfragment_entry,
+					start_block, offset,
+					sizeof(sfragment_entry), &start_block,
+					&offset))
+			goto out;
+		SQUASHFS_SWAP_FRAGMENT_ENTRY(&fragment_entry, &sfragment_entry);
+	} else
+		if (!squashfs_get_cached_block(s, (char *) &fragment_entry,
+					start_block, offset,
+					sizeof(fragment_entry), &start_block,
+					&offset))
+			goto out;
+
+	*fragment_start_block = fragment_entry.start_block;
+	*fragment_size = fragment_entry.size;
+
+	return 1;
+
+out:
+	return 0;
+}
+
+
+SQSH_EXTERN void release_cached_fragment(struct squashfs_sb_info *msblk, struct
+					squashfs_fragment_cache *fragment)
+{
+	down(&msblk->fragment_mutex);
+	fragment->locked --;
+	wake_up(&msblk->fragment_wait_queue);
+	up(&msblk->fragment_mutex);
+}
+
+
+SQSH_EXTERN struct squashfs_fragment_cache *get_cached_fragment(struct super_block
+					*s, long long start_block,
+					int length)
+{
+	int i, n;
+	struct squashfs_sb_info *msblk = &s->u.squashfs_sb;
+
+	while ( 1 ) {
+		down(&msblk->fragment_mutex);
+
+		for (i = 0; i < SQUASHFS_CACHED_FRAGMENTS &&
+				msblk->fragment[i].block != start_block; i++);
+
+		if (i == SQUASHFS_CACHED_FRAGMENTS) {
+			for (i = msblk->next_fragment, n =
+				SQUASHFS_CACHED_FRAGMENTS; n &&
+				msblk->fragment[i].locked; n--, i = (i + 1) %
+				SQUASHFS_CACHED_FRAGMENTS);
+
+			if (n == 0) {
+				wait_queue_t wait;
+
+				init_waitqueue_entry(&wait, current);
+				add_wait_queue(&msblk->fragment_wait_queue,
+									&wait);
+				set_current_state(TASK_UNINTERRUPTIBLE);
+				up(&msblk->fragment_mutex);
+				schedule();
+				set_current_state(TASK_RUNNING);
+				remove_wait_queue(&msblk->fragment_wait_queue,
+									&wait);
+				continue;
+			}
+			msblk->next_fragment = (msblk->next_fragment + 1) %
+				SQUASHFS_CACHED_FRAGMENTS;
+			
+			if (msblk->fragment[i].data == NULL)
+				if (!(msblk->fragment[i].data = SQUASHFS_ALLOC
+						(SQUASHFS_FILE_MAX_SIZE))) {
+					ERROR("Failed to allocate fragment "
+							"cache block\n");
+					up(&msblk->fragment_mutex);
+					goto out;
+				}
+
+			msblk->fragment[i].block = SQUASHFS_INVALID_BLK;
+			msblk->fragment[i].locked = 1;
+			up(&msblk->fragment_mutex);
+
+			if (!(msblk->fragment[i].length = squashfs_read_data(s,
+						msblk->fragment[i].data,
+						start_block, length, NULL))) {
+				ERROR("Unable to read fragment cache block "
+							"[%llx]\n", start_block);
+				msblk->fragment[i].locked = 0;
+				goto out;
+			}
+
+			msblk->fragment[i].block = start_block;
+			TRACE("New fragment %d, start block %lld, locked %d\n",
+						i, msblk->fragment[i].block,
+						msblk->fragment[i].locked);
+			break;
+		}
+
+		msblk->fragment[i].locked++;
+		up(&msblk->fragment_mutex);
+		TRACE("Got fragment %d, start block %lld, locked %d\n", i,
+						msblk->fragment[i].block,
+						msblk->fragment[i].locked);
+		break;
+	}
+
+	return &msblk->fragment[i];
+
+out:
+	return NULL;
+}
+
+
+static struct inode *squashfs_new_inode(struct super_block *s,
+		struct squashfs_base_inode_header *inodeb)
+{
+	struct squashfs_sb_info *msblk = &s->u.squashfs_sb;
+	struct inode *i = new_inode(s);
+
+	if (i) {
+		i->i_ino = inodeb->inode_number;
+		i->i_mtime = inodeb->mtime;
+		i->i_atime = inodeb->mtime;
+		i->i_ctime = inodeb->mtime;
+		i->i_uid = msblk->uid[inodeb->uid];
+		i->i_mode = inodeb->mode;
+		i->i_size = 0;
+		if (inodeb->guid == SQUASHFS_GUIDS)
+			i->i_gid = i->i_uid;
+		else
+			i->i_gid = msblk->guid[inodeb->guid];
+	}
+
+	return i;
+}
+
+
+static struct inode *squashfs_iget(struct super_block *s, squashfs_inode_t inode)
+{
+	struct inode *i;
+	struct squashfs_sb_info *msblk = &s->u.squashfs_sb;
+	struct squashfs_super_block *sblk = &msblk->sblk;
+	long long block = SQUASHFS_INODE_BLK(inode) +
+		sblk->inode_table_start;
+	unsigned int offset = SQUASHFS_INODE_OFFSET(inode);
+	long long next_block;
+	unsigned int next_offset;
+	union squashfs_inode_header id, sid;
+	struct squashfs_base_inode_header *inodeb = &id.base,
+					  *sinodeb = &sid.base;
+
+	TRACE("Entered squashfs_iget\n");
+
+	if (msblk->swap) {
+		if (!squashfs_get_cached_block(s, (char *) sinodeb, block,
+					offset, sizeof(*sinodeb), &next_block,
+					&next_offset))
+			goto failed_read;
+		SQUASHFS_SWAP_BASE_INODE_HEADER(inodeb, sinodeb,
+					sizeof(*sinodeb));
+	} else
+		if (!squashfs_get_cached_block(s, (char *) inodeb, block,
+					offset, sizeof(*inodeb), &next_block,
+					&next_offset))
+			goto failed_read;
+
+	switch(inodeb->inode_type) {
+		case SQUASHFS_FILE_TYPE: {
+			unsigned int frag_size;
+			long long frag_blk;
+			struct squashfs_reg_inode_header *inodep = &id.reg;
+			struct squashfs_reg_inode_header *sinodep = &sid.reg;
+				
+			if (msblk->swap) {
+				if (!squashfs_get_cached_block(s, (char *)
+						sinodep, block, offset,
+						sizeof(*sinodep), &next_block,
+						&next_offset))
+					goto failed_read;
+				SQUASHFS_SWAP_REG_INODE_HEADER(inodep, sinodep);
+			} else
+				if (!squashfs_get_cached_block(s, (char *)
+						inodep, block, offset,
+						sizeof(*inodep), &next_block,
+						&next_offset))
+					goto failed_read;
+
+			frag_blk = SQUASHFS_INVALID_BLK;
+			if (inodep->fragment != SQUASHFS_INVALID_FRAG &&
+					!get_fragment_location(s,
+					inodep->fragment, &frag_blk, &frag_size))
+				goto failed_read;
+				
+			if((i = squashfs_new_inode(s, inodeb)) == NULL)
+				goto failed_read1;
+
+			i->i_nlink = 1;
+			i->i_size = inodep->file_size;
+			i->i_fop = &generic_ro_fops;
+			i->i_mode |= S_IFREG;
+			i->i_blocks = ((i->i_size - 1) >> 9) + 1;
+			i->i_blksize = PAGE_CACHE_SIZE;
+			SQUASHFS_I(i)->u.s1.fragment_start_block = frag_blk;
+			SQUASHFS_I(i)->u.s1.fragment_size = frag_size;
+			SQUASHFS_I(i)->u.s1.fragment_offset = inodep->offset;
+			SQUASHFS_I(i)->start_block = inodep->start_block;
+			SQUASHFS_I(i)->u.s1.block_list_start = next_block;
+			SQUASHFS_I(i)->offset = next_offset;
+			if (sblk->block_size > 4096)
+				i->i_data.a_ops = &squashfs_aops;
+			else
+				i->i_data.a_ops = &squashfs_aops_4K;
+
+			TRACE("File inode %x:%x, start_block %llx, "
+					"block_list_start %llx, offset %x\n",
+					SQUASHFS_INODE_BLK(inode), offset,
+					inodep->start_block, next_block,
+					next_offset);
+			break;
+		}
+		case SQUASHFS_LREG_TYPE: {
+			unsigned int frag_size;
+			long long frag_blk;
+			struct squashfs_lreg_inode_header *inodep = &id.lreg;
+			struct squashfs_lreg_inode_header *sinodep = &sid.lreg;
+				
+			if (msblk->swap) {
+				if (!squashfs_get_cached_block(s, (char *)
+						sinodep, block, offset,
+						sizeof(*sinodep), &next_block,
+						&next_offset))
+					goto failed_read;
+				SQUASHFS_SWAP_LREG_INODE_HEADER(inodep, sinodep);
+			} else
+				if (!squashfs_get_cached_block(s, (char *)
+						inodep, block, offset,
+						sizeof(*inodep), &next_block,
+						&next_offset))
+					goto failed_read;
+
+			frag_blk = SQUASHFS_INVALID_BLK;
+			if (inodep->fragment != SQUASHFS_INVALID_FRAG &&
+					!get_fragment_location(s,
+					inodep->fragment, &frag_blk, &frag_size))
+				goto failed_read;
+				
+			if((i = squashfs_new_inode(s, inodeb)) == NULL)
+				goto failed_read1;
+
+			i->i_nlink = inodep->nlink;
+			i->i_size = inodep->file_size;
+			i->i_fop = &generic_ro_fops;
+			i->i_mode |= S_IFREG;
+			i->i_blocks = ((i->i_size - 1) >> 9) + 1;
+			i->i_blksize = PAGE_CACHE_SIZE;
+			SQUASHFS_I(i)->u.s1.fragment_start_block = frag_blk;
+			SQUASHFS_I(i)->u.s1.fragment_size = frag_size;
+			SQUASHFS_I(i)->u.s1.fragment_offset = inodep->offset;
+			SQUASHFS_I(i)->start_block = inodep->start_block;
+			SQUASHFS_I(i)->u.s1.block_list_start = next_block;
+			SQUASHFS_I(i)->offset = next_offset;
+			if (sblk->block_size > 4096)
+				i->i_data.a_ops = &squashfs_aops;
+			else
+				i->i_data.a_ops = &squashfs_aops_4K;
+
+			TRACE("File inode %x:%x, start_block %llx, "
+					"block_list_start %llx, offset %x\n",
+					SQUASHFS_INODE_BLK(inode), offset,
+					inodep->start_block, next_block,
+					next_offset);
+			break;
+		}
+		case SQUASHFS_DIR_TYPE: {
+			struct squashfs_dir_inode_header *inodep = &id.dir;
+			struct squashfs_dir_inode_header *sinodep = &sid.dir;
+
+			if (msblk->swap) {
+				if (!squashfs_get_cached_block(s, (char *)
+						sinodep, block, offset,
+						sizeof(*sinodep), &next_block,
+						&next_offset))
+					goto failed_read;
+				SQUASHFS_SWAP_DIR_INODE_HEADER(inodep, sinodep);
+			} else
+				if (!squashfs_get_cached_block(s, (char *)
+						inodep, block, offset,
+						sizeof(*inodep), &next_block,
+						&next_offset))
+					goto failed_read;
+
+			if((i = squashfs_new_inode(s, inodeb)) == NULL)
+				goto failed_read1;
+
+			i->i_nlink = inodep->nlink;
+			i->i_size = inodep->file_size;
+			i->i_op = &squashfs_dir_inode_ops;
+			i->i_fop = &squashfs_dir_ops;
+			i->i_mode |= S_IFDIR;
+			SQUASHFS_I(i)->start_block = inodep->start_block;
+			SQUASHFS_I(i)->offset = inodep->offset;
+			SQUASHFS_I(i)->u.s2.directory_index_count = 0;
+			SQUASHFS_I(i)->u.s2.parent_inode = inodep->parent_inode;
+
+			TRACE("Directory inode %x:%x, start_block %x, offset "
+					"%x\n", SQUASHFS_INODE_BLK(inode),
+					offset, inodep->start_block,
+					inodep->offset);
+			break;
+		}
+		case SQUASHFS_LDIR_TYPE: {
+			struct squashfs_ldir_inode_header *inodep = &id.ldir;
+			struct squashfs_ldir_inode_header *sinodep = &sid.ldir;
+
+			if (msblk->swap) {
+				if (!squashfs_get_cached_block(s, (char *)
+						sinodep, block, offset,
+						sizeof(*sinodep), &next_block,
+						&next_offset))
+					goto failed_read;
+				SQUASHFS_SWAP_LDIR_INODE_HEADER(inodep,
+						sinodep);
+			} else
+				if (!squashfs_get_cached_block(s, (char *)
+						inodep, block, offset,
+						sizeof(*inodep), &next_block,
+						&next_offset))
+					goto failed_read;
+
+			if((i = squashfs_new_inode(s, inodeb)) == NULL)
+				goto failed_read1;
+
+			i->i_nlink = inodep->nlink;
+			i->i_size = inodep->file_size;
+			i->i_op = &squashfs_dir_inode_ops;
+			i->i_fop = &squashfs_dir_ops;
+			i->i_mode |= S_IFDIR;
+			SQUASHFS_I(i)->start_block = inodep->start_block;
+			SQUASHFS_I(i)->offset = inodep->offset;
+			SQUASHFS_I(i)->u.s2.directory_index_start = next_block;
+			SQUASHFS_I(i)->u.s2.directory_index_offset =
+								next_offset;
+			SQUASHFS_I(i)->u.s2.directory_index_count =
+								inodep->i_count;
+			SQUASHFS_I(i)->u.s2.parent_inode = inodep->parent_inode;
+
+			TRACE("Long directory inode %x:%x, start_block %x, "
+					"offset %x\n",
+					SQUASHFS_INODE_BLK(inode), offset,
+					inodep->start_block, inodep->offset);
+			break;
+		}
+		case SQUASHFS_SYMLINK_TYPE: {
+			struct squashfs_symlink_inode_header *inodep =
+								&id.symlink;
+			struct squashfs_symlink_inode_header *sinodep =
+								&sid.symlink;
+	
+			if (msblk->swap) {
+				if (!squashfs_get_cached_block(s, (char *)
+						sinodep, block, offset,
+						sizeof(*sinodep), &next_block,
+						&next_offset))
+					goto failed_read;
+				SQUASHFS_SWAP_SYMLINK_INODE_HEADER(inodep,
+								sinodep);
+			} else
+				if (!squashfs_get_cached_block(s, (char *)
+						inodep, block, offset,
+						sizeof(*inodep), &next_block,
+						&next_offset))
+					goto failed_read;
+
+			if((i = squashfs_new_inode(s, inodeb)) == NULL)
+				goto failed_read1;
+
+			i->i_nlink = inodep->nlink;
+			i->i_size = inodep->symlink_size;
+			i->i_op = &page_symlink_inode_operations;
+			i->i_data.a_ops = &squashfs_symlink_aops;
+			i->i_mode |= S_IFLNK;
+			SQUASHFS_I(i)->start_block = next_block;
+			SQUASHFS_I(i)->offset = next_offset;
+
+			TRACE("Symbolic link inode %x:%x, start_block %llx, "
+					"offset %x\n",
+					SQUASHFS_INODE_BLK(inode), offset,
+					next_block, next_offset);
+			break;
+		 }
+		 case SQUASHFS_BLKDEV_TYPE:
+		 case SQUASHFS_CHRDEV_TYPE: {
+			struct squashfs_dev_inode_header *inodep = &id.dev;
+			struct squashfs_dev_inode_header *sinodep = &sid.dev;
+
+			if (msblk->swap) {
+				if (!squashfs_get_cached_block(s, (char *)
+						sinodep, block, offset,
+						sizeof(*sinodep), &next_block,
+						&next_offset))
+					goto failed_read;
+				SQUASHFS_SWAP_DEV_INODE_HEADER(inodep, sinodep);
+			} else	
+				if (!squashfs_get_cached_block(s, (char *)
+						inodep, block, offset,
+						sizeof(*inodep), &next_block,
+						&next_offset))
+					goto failed_read;
+
+			if ((i = squashfs_new_inode(s, inodeb)) == NULL)
+				goto failed_read1;
+
+			i->i_nlink = inodep->nlink;
+			i->i_mode |= (inodeb->inode_type ==
+					SQUASHFS_CHRDEV_TYPE) ?  S_IFCHR :
+					S_IFBLK;
+			init_special_inode(i, i->i_mode, inodep->rdev);
+
+			TRACE("Device inode %x:%x, rdev %x\n",
+					SQUASHFS_INODE_BLK(inode), offset,
+					inodep->rdev);
+			break;
+		 }
+		 case SQUASHFS_FIFO_TYPE:
+		 case SQUASHFS_SOCKET_TYPE: {
+			struct squashfs_ipc_inode_header *inodep = &id.ipc;
+			struct squashfs_ipc_inode_header *sinodep = &sid.ipc;
+
+			if (msblk->swap) {
+				if (!squashfs_get_cached_block(s, (char *)
+						sinodep, block, offset,
+						sizeof(*sinodep), &next_block,
+						&next_offset))
+					goto failed_read;
+				SQUASHFS_SWAP_IPC_INODE_HEADER(inodep, sinodep);
+			} else	
+				if (!squashfs_get_cached_block(s, (char *)
+						inodep, block, offset,
+						sizeof(*inodep), &next_block,
+						&next_offset))
+					goto failed_read;
+
+			if ((i = squashfs_new_inode(s, inodeb)) == NULL)
+				goto failed_read1;
+
+			i->i_nlink = inodep->nlink;
+			i->i_mode |= (inodeb->inode_type == SQUASHFS_FIFO_TYPE)
+							? S_IFIFO : S_IFSOCK;
+			init_special_inode(i, i->i_mode, 0);
+			break;
+		 }
+		 default:
+			ERROR("Unknown inode type %d in squashfs_iget!\n",
+					inodeb->inode_type);
+			goto failed_read1;
+	}
+	
+	insert_inode_hash(i);
+	return i;
+
+failed_read:
+	ERROR("Unable to read inode [%llx:%x]\n", block, offset);
+
+failed_read1:
+	return NULL;
+}
+
+
+int read_fragment_index_table(struct super_block *s)
+{
+	struct squashfs_sb_info *msblk = &s->u.squashfs_sb;
+	struct squashfs_super_block *sblk = &msblk->sblk;
+
+	if (!(msblk->fragment_index = kmalloc(SQUASHFS_FRAGMENT_INDEX_BYTES
+					(sblk->fragments), GFP_KERNEL))) {
+		ERROR("Failed to allocate uid/gid table\n");
+		return 0;
+	}
+   
+	if (SQUASHFS_FRAGMENT_INDEX_BYTES(sblk->fragments) &&
+					!squashfs_read_data(s, (char *)
+					msblk->fragment_index,
+					sblk->fragment_table_start,
+					SQUASHFS_FRAGMENT_INDEX_BYTES
+					(sblk->fragments) |
+					SQUASHFS_COMPRESSED_BIT_BLOCK, NULL)) {
+		ERROR("unable to read fragment index table\n");
+		return 0;
+	}
+
+	if (msblk->swap) {
+		int i;
+		long long fragment;
+
+		for (i = 0; i < SQUASHFS_FRAGMENT_INDEXES(sblk->fragments);
+									i++) {
+			SQUASHFS_SWAP_FRAGMENT_INDEXES((&fragment),
+						&msblk->fragment_index[i], 1);
+			msblk->fragment_index[i] = fragment;
+		}
+	}
+
+	return 1;
+}
+
+
+static int supported_squashfs_filesystem(struct squashfs_sb_info *msblk, int silent)
+{
+	struct squashfs_super_block *sblk = &msblk->sblk;
+
+	msblk->iget = squashfs_iget;
+	msblk->read_blocklist = read_blocklist;
+	msblk->read_fragment_index_table = read_fragment_index_table;
+
+	if (sblk->s_major == 1) {
+		if (!squashfs_1_0_supported(msblk)) {
+			SERROR("Major/Minor mismatch, Squashfs 1.0 filesystems "
+				"are unsupported\n");
+			SERROR("Please recompile with "
+				"Squashfs 1.0 support enabled\n");
+			return 0;
+		}
+	} else if (sblk->s_major == 2) {
+		if (!squashfs_2_0_supported(msblk)) {
+			SERROR("Major/Minor mismatch, Squashfs 2.0 filesystems "
+				"are unsupported\n");
+			SERROR("Please recompile with "
+				"Squashfs 2.0 support enabled\n");
+			return 0;
+		}
+	} else if(sblk->s_major != SQUASHFS_MAJOR || sblk->s_minor >
+			SQUASHFS_MINOR) {
+		SERROR("Major/Minor mismatch, trying to mount newer %d.%d "
+				"filesystem\n", sblk->s_major, sblk->s_minor);
+		SERROR("Please update your kernel\n");
+		return 0;
+	}
+
+	return 1;
+}
+
+
+static struct super_block *squashfs_read_super(struct super_block *s,
+		void *data, int silent)
+{
+	kdev_t dev = s->s_dev;
+	struct squashfs_sb_info *msblk = &s->u.squashfs_sb;
+	struct squashfs_super_block *sblk = &msblk->sblk;
+	int i;
+	struct inode *root;
+
+	if (!(msblk->stream.workspace = vmalloc(zlib_inflate_workspacesize()))) {
+		ERROR("Failed to allocate zlib workspace\n");
+		goto failed_mount;
+	}
+
+	msblk->devblksize = get_hardsect_size(dev);
+	if(msblk->devblksize < BLOCK_SIZE)
+		msblk->devblksize = BLOCK_SIZE;
+	msblk->devblksize_log2 = ffz(~msblk->devblksize);
+        set_blocksize(dev, msblk->devblksize);
+	s->s_blocksize = msblk->devblksize;
+	s->s_blocksize_bits = msblk->devblksize_log2;
+	
+	init_MUTEX(&msblk->read_data_mutex);
+	init_MUTEX(&msblk->read_page_mutex);
+	init_MUTEX(&msblk->block_cache_mutex);
+	init_MUTEX(&msblk->fragment_mutex);
+	
+	init_waitqueue_head(&msblk->waitq);
+	init_waitqueue_head(&msblk->fragment_wait_queue);
+
+	if (!squashfs_read_data(s, (char *) sblk, SQUASHFS_START,
+					sizeof(struct squashfs_super_block) |
+					SQUASHFS_COMPRESSED_BIT_BLOCK, NULL)) {
+		SERROR("unable to read superblock\n");
+		goto failed_mount;
+	}
+
+	/* Check it is a SQUASHFS superblock */
+	msblk->swap = 0;
+	if ((s->s_magic = sblk->s_magic) != SQUASHFS_MAGIC) {
+		if (sblk->s_magic == SQUASHFS_MAGIC_SWAP) {
+			struct squashfs_super_block ssblk;
+
+			WARNING("Mounting a different endian SQUASHFS "
+				"filesystem on %s\n", bdevname(dev));
+
+			SQUASHFS_SWAP_SUPER_BLOCK(&ssblk, sblk);
+			memcpy(sblk, &ssblk, sizeof(struct squashfs_super_block));
+			msblk->swap = 1;
+		} else  {
+			SERROR("Can't find a SQUASHFS superblock on %s\n",
+							bdevname(dev));
+			goto failed_mount;
+		}
+	}
+
+	/* Check the MAJOR & MINOR versions */
+	if(!supported_squashfs_filesystem(msblk, silent))
+		goto failed_mount;
+
+	TRACE("Found valid superblock on %s\n", bdevname(dev));
+	TRACE("Inodes are %scompressed\n",
+					SQUASHFS_UNCOMPRESSED_INODES
+					(sblk->flags) ? "un" : "");
+	TRACE("Data is %scompressed\n",
+					SQUASHFS_UNCOMPRESSED_DATA(sblk->flags)
+					? "un" : "");
+	TRACE("Check data is %s present in the filesystem\n",
+					SQUASHFS_CHECK_DATA(sblk->flags) ?
+					"" : "not");
+	TRACE("Filesystem size %lld bytes\n", sblk->bytes_used);
+	TRACE("Block size %d\n", sblk->block_size);
+	TRACE("Number of inodes %d\n", sblk->inodes);
+	if (sblk->s_major > 1)
+		TRACE("Number of fragments %d\n", sblk->fragments);
+	TRACE("Number of uids %d\n", sblk->no_uids);
+	TRACE("Number of gids %d\n", sblk->no_guids);
+	TRACE("sblk->inode_table_start %llx\n", sblk->inode_table_start);
+	TRACE("sblk->directory_table_start %llx\n", sblk->directory_table_start);
+	if (sblk->s_major > 1)
+		TRACE("sblk->fragment_table_start %llx\n",
+					sblk->fragment_table_start);
+	TRACE("sblk->uid_start %llx\n", sblk->uid_start);
+
+	s->s_flags |= MS_RDONLY;
+	s->s_op = &squashfs_ops;
+
+	/* Init inode_table block pointer array */
+	if (!(msblk->block_cache = kmalloc(sizeof(struct squashfs_cache) *
+					SQUASHFS_CACHED_BLKS, GFP_KERNEL))) {
+		ERROR("Failed to allocate block cache\n");
+		goto failed_mount;
+	}
+
+	for (i = 0; i < SQUASHFS_CACHED_BLKS; i++)
+		msblk->block_cache[i].block = SQUASHFS_INVALID_BLK;
+
+	msblk->next_cache = 0;
+
+	/* Allocate read_data block */
+	msblk->read_size = (sblk->block_size < SQUASHFS_METADATA_SIZE) ?
+					SQUASHFS_METADATA_SIZE :
+					sblk->block_size;
+
+	if (!(msblk->read_data = kmalloc(msblk->read_size, GFP_KERNEL))) {
+		ERROR("Failed to allocate read_data block\n");
+		goto failed_mount;
+	}
+
+	/* Allocate read_page block */
+	if (!(msblk->read_page = kmalloc(sblk->block_size, GFP_KERNEL))) {
+		ERROR("Failed to allocate read_page block\n");
+		goto failed_mount;
+	}
+
+	/* Allocate uid and gid tables */
+	if (!(msblk->uid = kmalloc((sblk->no_uids + sblk->no_guids) *
+					sizeof(unsigned int), GFP_KERNEL))) {
+		ERROR("Failed to allocate uid/gid table\n");
+		goto failed_mount;
+	}
+	msblk->guid = msblk->uid + sblk->no_uids;
+   
+	if (msblk->swap) {
+		unsigned int suid[sblk->no_uids + sblk->no_guids];
+
+		if (!squashfs_read_data(s, (char *) &suid, sblk->uid_start,
+					((sblk->no_uids + sblk->no_guids) *
+					 sizeof(unsigned int)) |
+					SQUASHFS_COMPRESSED_BIT_BLOCK, NULL)) {
+			ERROR("unable to read uid/gid table\n");
+			goto failed_mount;
+		}
+
+		SQUASHFS_SWAP_DATA(msblk->uid, suid, (sblk->no_uids +
+			sblk->no_guids), (sizeof(unsigned int) * 8));
+	} else
+		if (!squashfs_read_data(s, (char *) msblk->uid, sblk->uid_start,
+					((sblk->no_uids + sblk->no_guids) *
+					 sizeof(unsigned int)) |
+					SQUASHFS_COMPRESSED_BIT_BLOCK, NULL)) {
+			ERROR("unable to read uid/gid table\n");
+			goto failed_mount;
+		}
+
+
+	if (sblk->s_major == 1 && squashfs_1_0_supported(msblk))
+		goto allocate_root;
+
+	if (!(msblk->fragment = kmalloc(sizeof(struct squashfs_fragment_cache) *
+				SQUASHFS_CACHED_FRAGMENTS, GFP_KERNEL))) {
+		ERROR("Failed to allocate fragment block cache\n");
+		goto failed_mount;
+	}
+
+	for (i = 0; i < SQUASHFS_CACHED_FRAGMENTS; i++) {
+		msblk->fragment[i].locked = 0;
+		msblk->fragment[i].block = SQUASHFS_INVALID_BLK;
+		msblk->fragment[i].data = NULL;
+	}
+
+	msblk->next_fragment = 0;
+
+	/* Allocate fragment index table */
+	if(msblk->read_fragment_index_table(s) == 0)
+		goto failed_mount;
+
+allocate_root:
+	if ((root = (msblk->iget)(s, sblk->root_inode)) == NULL)
+		goto failed_mount;
+
+	if ((s->s_root = d_alloc_root(root)) == NULL) {
+		ERROR("Root inode create failed\n");
+		iput(root);
+		goto failed_mount;
+	}
+
+	TRACE("Leaving squashfs_read_super\n");
+	return s;
+
+failed_mount:
+	kfree(msblk->fragment_index);
+	kfree(msblk->fragment);
+	kfree(msblk->uid);
+	kfree(msblk->read_page);
+	kfree(msblk->read_data);
+	kfree(msblk->block_cache);
+	kfree(msblk->fragment_index_2);
+	vfree(msblk->stream.workspace);
+	return NULL;
+}
+
+
+static int squashfs_statfs(struct super_block *s, struct statfs *buf)
+{
+	struct squashfs_sb_info *msblk = &s->u.squashfs_sb;
+	struct squashfs_super_block *sblk = &msblk->sblk;
+
+	TRACE("Entered squashfs_statfs\n");
+
+	buf->f_type = SQUASHFS_MAGIC;
+	buf->f_bsize = sblk->block_size;
+	buf->f_blocks = ((sblk->bytes_used - 1) >> sblk->block_log) + 1;
+	buf->f_bfree = buf->f_bavail = 0;
+	buf->f_files = sblk->inodes;
+	buf->f_ffree = 0;
+	buf->f_namelen = SQUASHFS_NAME_LEN;
+
+	return 0;
+}
+
+
+static int squashfs_symlink_readpage(struct file *file, struct page *page)
+{
+	struct inode *inode = page->mapping->host;
+	int index = page->index << PAGE_CACHE_SHIFT, length, bytes;
+	long long block = SQUASHFS_I(inode)->start_block;
+	int offset = SQUASHFS_I(inode)->offset;
+	void *pageaddr = kmap(page);
+
+	TRACE("Entered squashfs_symlink_readpage, page index %ld, start block "
+				"%llx, offset %x\n", page->index,
+				SQUASHFS_I(inode)->start_block,
+				SQUASHFS_I(inode)->offset);
+
+	for (length = 0; length < index; length += bytes) {
+		if (!(bytes = squashfs_get_cached_block(inode->i_sb, NULL,
+				block, offset, PAGE_CACHE_SIZE, &block,
+				&offset))) {
+			ERROR("Unable to read symbolic link [%llx:%x]\n", block,
+					offset);
+			goto skip_read;
+		}
+	}
+
+	if (length != index) {
+		ERROR("(squashfs_symlink_readpage) length != index\n");
+		bytes = 0;
+		goto skip_read;
+	}
+
+	bytes = (i_size_read(inode) - length) > PAGE_CACHE_SIZE ? PAGE_CACHE_SIZE :
+					i_size_read(inode) - length;
+
+	if (!(bytes = squashfs_get_cached_block(inode->i_sb, pageaddr, block,
+					offset, bytes, &block, &offset)))
+		ERROR("Unable to read symbolic link [%llx:%x]\n", block, offset);
+
+skip_read:
+	memset(pageaddr + bytes, 0, PAGE_CACHE_SIZE - bytes);
+	kunmap(page);
+	SetPageUptodate(page);
+	UnlockPage(page);
+
+	return 0;
+}
+
+
+struct meta_index *locate_meta_index(struct inode *inode, int index, int offset)
+{
+	struct meta_index *meta = NULL;
+	struct squashfs_sb_info *msblk = &inode->i_sb->u.squashfs_sb;
+	int i;
+
+	down(&msblk->meta_index_mutex);
+
+	TRACE("locate_meta_index: index %d, offset %d\n", index, offset);
+
+	if(msblk->meta_index == NULL)
+		goto not_allocated;
+
+	for (i = 0; i < SQUASHFS_META_NUMBER; i ++)
+		if (msblk->meta_index[i].inode_number == inode->i_ino &&
+				msblk->meta_index[i].offset >= offset &&
+				msblk->meta_index[i].offset <= index &&
+				msblk->meta_index[i].locked == 0) {
+			TRACE("locate_meta_index: entry %d, offset %d\n", i,
+					msblk->meta_index[i].offset);
+			meta = &msblk->meta_index[i];
+			offset = meta->offset;
+		}
+
+	if (meta)
+		meta->locked = 1;
+
+not_allocated:
+	up(&msblk->meta_index_mutex);
+
+	return meta;
+}
+
+
+struct meta_index *empty_meta_index(struct inode *inode, int offset, int skip)
+{
+	struct squashfs_sb_info *msblk = &inode->i_sb->u.squashfs_sb;
+	struct meta_index *meta = NULL;
+	int i;
+
+	down(&msblk->meta_index_mutex);
+
+	TRACE("empty_meta_index: offset %d, skip %d\n", offset, skip);
+
+	if(msblk->meta_index == NULL) {
+		if (!(msblk->meta_index = kmalloc(sizeof(struct meta_index) *
+					SQUASHFS_META_NUMBER, GFP_KERNEL))) {
+			ERROR("Failed to allocate meta_index\n");
+			goto failed;
+		}
+		for(i = 0; i < SQUASHFS_META_NUMBER; i++) {
+			msblk->meta_index[i].inode_number = 0;
+			msblk->meta_index[i].locked = 0;
+		}
+		msblk->next_meta_index = 0;
+	}
+
+	for(i = SQUASHFS_META_NUMBER; i &&
+			msblk->meta_index[msblk->next_meta_index].locked; i --)
+		msblk->next_meta_index = (msblk->next_meta_index + 1) %
+			SQUASHFS_META_NUMBER;
+
+	if(i == 0) {
+		TRACE("empty_meta_index: failed!\n");
+		goto failed;
+	}
+
+	TRACE("empty_meta_index: returned meta entry %d, %p\n",
+			msblk->next_meta_index,
+			&msblk->meta_index[msblk->next_meta_index]);
+
+	meta = &msblk->meta_index[msblk->next_meta_index];
+	msblk->next_meta_index = (msblk->next_meta_index + 1) %
+			SQUASHFS_META_NUMBER;
+
+	meta->inode_number = inode->i_ino;
+	meta->offset = offset;
+	meta->skip = skip;
+	meta->entries = 0;
+	meta->locked = 1;
+
+failed:
+	up(&msblk->meta_index_mutex);
+	return meta;
+}
+
+
+void release_meta_index(struct inode *inode, struct meta_index *meta)
+{
+	meta->locked = 0;
+}
+
+
+static int read_block_index(struct super_block *s, int blocks, char *block_list,
+		long long *start_block, int *offset)
+{
+	struct squashfs_sb_info *msblk = &s->u.squashfs_sb;
+	unsigned int *block_listp;
+	int block = 0;
+	
+	if (msblk->swap) {
+		char sblock_list[blocks << 2];
+
+		if (!squashfs_get_cached_block(s, sblock_list, *start_block,
+				*offset, blocks << 2, start_block, offset)) {
+			ERROR("Unable to read block list [%llx:%x]\n",
+				*start_block, *offset);
+			goto failure;
+		}
+		SQUASHFS_SWAP_INTS(((unsigned int *)block_list),
+				((unsigned int *)sblock_list), blocks);
+	} else
+		if (!squashfs_get_cached_block(s, block_list, *start_block,
+				*offset, blocks << 2, start_block, offset)) {
+			ERROR("Unable to read block list [%llx:%x]\n",
+				*start_block, *offset);
+			goto failure;
+		}
+
+	for (block_listp = (unsigned int *) block_list; blocks;
+				block_listp++, blocks --)
+		block += SQUASHFS_COMPRESSED_SIZE_BLOCK(*block_listp);
+
+	return block;
+
+failure:
+	return -1;
+}
+
+
+#define SIZE 256
+
+static inline int calculate_skip(int blocks) {
+	int skip = (blocks - 1) / ((SQUASHFS_SLOTS * SQUASHFS_META_ENTRIES + 1) * SQUASHFS_META_INDEXES);
+	return skip >= 7 ? 7 : skip + 1;
+}
+
+
+static int get_meta_index(struct inode *inode, int index,
+		long long *index_block, int *index_offset,
+		long long *data_block, char *block_list)
+{
+	struct squashfs_sb_info *msblk = &inode->i_sb->u.squashfs_sb;
+	struct squashfs_super_block *sblk = &msblk->sblk;
+	int skip = calculate_skip(i_size_read(inode) >> sblk->block_log);
+	int offset = 0;
+	struct meta_index *meta;
+	struct meta_entry *meta_entry;
+	long long cur_index_block = SQUASHFS_I(inode)->u.s1.block_list_start;
+	int cur_offset = SQUASHFS_I(inode)->offset;
+	long long cur_data_block = SQUASHFS_I(inode)->start_block;
+	int i;
+ 
+	index /= SQUASHFS_META_INDEXES * skip;
+
+	while ( offset < index ) {
+		meta = locate_meta_index(inode, index, offset + 1);
+
+		if (meta == NULL) {
+			if ((meta = empty_meta_index(inode, offset + 1,
+							skip)) == NULL)
+				goto all_done;
+		} else {
+			offset = index < meta->offset + meta->entries ? index :
+				meta->offset + meta->entries - 1;
+			meta_entry = &meta->meta_entry[offset - meta->offset];
+			cur_index_block = meta_entry->index_block + sblk->inode_table_start;
+			cur_offset = meta_entry->offset;
+			cur_data_block = meta_entry->data_block;
+			TRACE("get_meta_index: offset %d, meta->offset %d, "
+				"meta->entries %d\n", offset, meta->offset,
+				meta->entries);
+			TRACE("get_meta_index: index_block 0x%llx, offset 0x%x"
+				" data_block 0x%llx\n", cur_index_block,
+				cur_offset, cur_data_block);
+		}
+
+		for (i = meta->offset + meta->entries; i <= index &&
+				i < meta->offset + SQUASHFS_META_ENTRIES; i++) {
+			int blocks = skip * SQUASHFS_META_INDEXES;
+
+			while (blocks) {
+				int block = blocks > (SIZE >> 2) ? (SIZE >> 2) :
+					blocks;
+				int res = read_block_index(inode->i_sb, block,
+					block_list, &cur_index_block,
+					&cur_offset);
+
+				if (res == -1)
+					goto failed;
+
+				cur_data_block += res;
+				blocks -= block;
+			}
+
+			meta_entry = &meta->meta_entry[i - meta->offset];
+			meta_entry->index_block = cur_index_block - sblk->inode_table_start;
+			meta_entry->offset = cur_offset;
+			meta_entry->data_block = cur_data_block;
+			meta->entries ++;
+			offset ++;
+		}
+
+		TRACE("get_meta_index: meta->offset %d, meta->entries %d\n",
+				meta->offset, meta->entries);
+
+		release_meta_index(inode, meta);
+	}
+
+all_done:
+	*index_block = cur_index_block;
+	*index_offset = cur_offset;
+	*data_block = cur_data_block;
+
+	return offset * SQUASHFS_META_INDEXES * skip;
+
+failed:
+	release_meta_index(inode, meta);
+	return -1;
+}
+
+
+static long long read_blocklist(struct inode *inode, int index,
+				int readahead_blks, char *block_list,
+				unsigned short **block_p, unsigned int *bsize)
+{
+	long long block_ptr;
+	int offset;
+	long long block;
+	int res = get_meta_index(inode, index, &block_ptr, &offset, &block,
+		block_list);
+
+	TRACE("read_blocklist: res %d, index %d, block_ptr 0x%llx, offset"
+		       " 0x%x, block 0x%llx\n", res, index, block_ptr, offset,
+		       block);
+
+	if(res == -1)
+		goto failure;
+
+	index -= res;
+
+	while ( index ) {
+		int blocks = index > (SIZE >> 2) ? (SIZE >> 2) : index;
+		int res = read_block_index(inode->i_sb, blocks, block_list,
+			&block_ptr, &offset);
+		if (res == -1)
+			goto failure;
+		block += res;
+		index -= blocks;
+	}
+
+	if (read_block_index(inode->i_sb, 1, block_list,
+			&block_ptr, &offset) == -1)
+		goto failure;
+	*bsize = *((unsigned int *) block_list);
+
+	return block;
+
+failure:
+	return 0;
+}
+
+
+static int squashfs_readpage(struct file *file, struct page *page)
+{
+	struct inode *inode = page->mapping->host;
+	struct squashfs_sb_info *msblk = &inode->i_sb->u.squashfs_sb;
+	struct squashfs_super_block *sblk = &msblk->sblk;
+	unsigned char block_list[SIZE];
+	long long block;
+	unsigned int bsize, i = 0, bytes = 0, byte_offset = 0;
+	int index = page->index >> (sblk->block_log - PAGE_CACHE_SHIFT);
+ 	void *pageaddr;
+	struct squashfs_fragment_cache *fragment = NULL;
+	char *data_ptr = msblk->read_page;
+	
+	int mask = (1 << (sblk->block_log - PAGE_CACHE_SHIFT)) - 1;
+	int start_index = page->index & ~mask;
+	int end_index = start_index | mask;
+
+	TRACE("Entered squashfs_readpage, page index %lx, start block %llx\n",
+					page->index,
+					SQUASHFS_I(inode)->start_block);
+
+	if (page->index >= ((i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
+					PAGE_CACHE_SHIFT))
+		goto skip_read;
+
+	if (SQUASHFS_I(inode)->u.s1.fragment_start_block == SQUASHFS_INVALID_BLK
+					|| index < (i_size_read(inode) >>
+					sblk->block_log)) {
+		if ((block = (msblk->read_blocklist)(inode, index, 1,
+					block_list, NULL, &bsize)) == 0)
+			goto skip_read;
+
+		down(&msblk->read_page_mutex);
+		
+		if (!(bytes = squashfs_read_data(inode->i_sb, msblk->read_page,
+					block, bsize, NULL))) {
+			ERROR("Unable to read page, block %llx, size %x\n", block,
+					bsize);
+			up(&msblk->read_page_mutex);
+			goto skip_read;
+		}
+	} else {
+		if ((fragment = get_cached_fragment(inode->i_sb,
+					SQUASHFS_I(inode)->
+					u.s1.fragment_start_block,
+					SQUASHFS_I(inode)->u.s1.fragment_size))
+					== NULL) {
+			ERROR("Unable to read page, block %llx, size %x\n",
+					SQUASHFS_I(inode)->
+					u.s1.fragment_start_block,
+					(int) SQUASHFS_I(inode)->
+					u.s1.fragment_size);
+			goto skip_read;
+		}
+		bytes = SQUASHFS_I(inode)->u.s1.fragment_offset +
+					(i_size_read(inode) & (sblk->block_size
+					- 1));
+		byte_offset = SQUASHFS_I(inode)->u.s1.fragment_offset;
+		data_ptr = fragment->data;
+	}
+
+	for (i = start_index; i <= end_index && byte_offset < bytes;
+					i++, byte_offset += PAGE_CACHE_SIZE) {
+		struct page *push_page;
+		int available_bytes = (bytes - byte_offset) > PAGE_CACHE_SIZE ?
+					PAGE_CACHE_SIZE : bytes - byte_offset;
+
+		TRACE("bytes %d, i %d, byte_offset %d, available_bytes %d\n",
+					bytes, i, byte_offset, available_bytes);
+
+		if (i == page->index)  {
+			pageaddr = kmap_atomic(page, KM_USER0);
+			memcpy(pageaddr, data_ptr + byte_offset,
+					available_bytes);
+			memset(pageaddr + available_bytes, 0,
+					PAGE_CACHE_SIZE - available_bytes);
+			kunmap_atomic(pageaddr, KM_USER0);
+			flush_dcache_page(page);
+			SetPageUptodate(page);
+			UnlockPage(page);
+		} else if ((push_page =
+				grab_cache_page_nowait(page->mapping, i))) {
+ 			pageaddr = kmap_atomic(push_page, KM_USER0);
+
+			memcpy(pageaddr, data_ptr + byte_offset,
+					available_bytes);
+			memset(pageaddr + available_bytes, 0,
+					PAGE_CACHE_SIZE - available_bytes);
+			kunmap_atomic(pageaddr, KM_USER0);
+			flush_dcache_page(push_page);
+			SetPageUptodate(push_page);
+			UnlockPage(push_page);
+			page_cache_release(push_page);
+		}
+	}
+
+	if (SQUASHFS_I(inode)->u.s1.fragment_start_block == SQUASHFS_INVALID_BLK
+					|| index < (i_size_read(inode) >>
+					sblk->block_log))
+		up(&msblk->read_page_mutex);
+	else
+		release_cached_fragment(msblk, fragment);
+
+	return 0;
+
+skip_read:
+	pageaddr = kmap_atomic(page, KM_USER0);
+	memset(pageaddr + bytes, 0, PAGE_CACHE_SIZE - bytes);
+	kunmap_atomic(pageaddr, KM_USER0);
+	flush_dcache_page(page);
+	SetPageUptodate(page);
+	UnlockPage(page);
+
+	return 0;
+}
+
+
+static int squashfs_readpage4K(struct file *file, struct page *page)
+{
+	struct inode *inode = page->mapping->host;
+	struct squashfs_sb_info *msblk = &inode->i_sb->u.squashfs_sb;
+	struct squashfs_super_block *sblk = &msblk->sblk;
+	unsigned char block_list[SIZE];
+	long long block;
+	unsigned int bsize, bytes = 0;
+ 	void *pageaddr;
+	
+	TRACE("Entered squashfs_readpage4K, page index %lx, start block %llx\n",
+					page->index,
+					SQUASHFS_I(inode)->start_block);
+
+	if (page->index >= ((i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
+					PAGE_CACHE_SHIFT)) {
+		pageaddr = kmap_atomic(page, KM_USER0);
+		goto skip_read;
+	}
+
+	if (SQUASHFS_I(inode)->u.s1.fragment_start_block == SQUASHFS_INVALID_BLK
+					|| page->index < (i_size_read(inode) >>
+					sblk->block_log)) {
+		block = (msblk->read_blocklist)(inode, page->index, 1,
+					block_list, NULL, &bsize);
+
+		down(&msblk->read_page_mutex);
+		bytes = squashfs_read_data(inode->i_sb, msblk->read_page, block,
+					bsize, NULL);
+		pageaddr = kmap_atomic(page, KM_USER0);
+		if (bytes)
+			memcpy(pageaddr, msblk->read_page, bytes);
+		else
+			ERROR("Unable to read page, block %llx, size %x\n",
+					block, bsize);
+		up(&msblk->read_page_mutex);
+	} else {
+		struct squashfs_fragment_cache *fragment =
+			get_cached_fragment(inode->i_sb,
+					SQUASHFS_I(inode)->
+					u.s1.fragment_start_block,
+					SQUASHFS_I(inode)-> u.s1.fragment_size);
+		pageaddr = kmap_atomic(page, KM_USER0);
+		if (fragment) {
+			bytes = i_size_read(inode) & (sblk->block_size - 1);
+			memcpy(pageaddr, fragment->data + SQUASHFS_I(inode)->
+					u.s1.fragment_offset, bytes);
+			release_cached_fragment(msblk, fragment);
+		} else
+			ERROR("Unable to read page, block %llx, size %x\n",
+					SQUASHFS_I(inode)->
+					u.s1.fragment_start_block, (int)
+					SQUASHFS_I(inode)-> u.s1.fragment_size);
+	}
+
+skip_read:
+	memset(pageaddr + bytes, 0, PAGE_CACHE_SIZE - bytes);
+	kunmap_atomic(pageaddr, KM_USER0);
+	flush_dcache_page(page);
+	SetPageUptodate(page);
+	UnlockPage(page);
+
+	return 0;
+}
+
+
+static int get_dir_index_using_offset(struct super_block *s, long long 
+				*next_block, unsigned int *next_offset,
+				long long index_start,
+				unsigned int index_offset, int i_count,
+				long long f_pos)
+{
+	struct squashfs_sb_info *msblk = &s->u.squashfs_sb;
+	struct squashfs_super_block *sblk = &msblk->sblk;
+	int i, length = 0;
+	struct squashfs_dir_index index;
+
+	TRACE("Entered get_dir_index_using_offset, i_count %d, f_pos %d\n",
+					i_count, (unsigned int) f_pos);
+
+	f_pos -= 3;
+	if (f_pos == 0)
+		goto finish;
+
+	for (i = 0; i < i_count; i++) {
+		if (msblk->swap) {
+			struct squashfs_dir_index sindex;
+			squashfs_get_cached_block(s, (char *) &sindex,
+					index_start, index_offset,
+					sizeof(sindex), &index_start,
+					&index_offset);
+			SQUASHFS_SWAP_DIR_INDEX(&index, &sindex);
+		} else
+			squashfs_get_cached_block(s, (char *) &index,
+					index_start, index_offset,
+					sizeof(index), &index_start,
+					&index_offset);
+
+		if (index.index > f_pos)
+			break;
+
+		squashfs_get_cached_block(s, NULL, index_start, index_offset,
+					index.size + 1, &index_start,
+					&index_offset);
+
+		length = index.index;
+		*next_block = index.start_block + sblk->directory_table_start;
+	}
+
+	*next_offset = (length + *next_offset) % SQUASHFS_METADATA_SIZE;
+
+finish:
+	return length + 3;
+}
+
+
+static int get_dir_index_using_name(struct super_block *s, long long
+				*next_block, unsigned int *next_offset,
+				long long index_start,
+				unsigned int index_offset, int i_count,
+				const char *name, int size)
+{
+	struct squashfs_sb_info *msblk = &s->u.squashfs_sb;
+	struct squashfs_super_block *sblk = &msblk->sblk;
+	int i, length = 0;
+	char buffer[sizeof(struct squashfs_dir_index) + SQUASHFS_NAME_LEN + 1];
+	struct squashfs_dir_index *index = (struct squashfs_dir_index *) buffer;
+	char str[SQUASHFS_NAME_LEN + 1];
+
+	TRACE("Entered get_dir_index_using_name, i_count %d\n", i_count);
+
+	strncpy(str, name, size);
+	str[size] = '\0';
+
+	for (i = 0; i < i_count; i++) {
+		if (msblk->swap) {
+			struct squashfs_dir_index sindex;
+			squashfs_get_cached_block(s, (char *) &sindex,
+					index_start, index_offset,
+					sizeof(sindex), &index_start,
+					&index_offset);
+			SQUASHFS_SWAP_DIR_INDEX(index, &sindex);
+		} else
+			squashfs_get_cached_block(s, (char *) index,
+					index_start, index_offset,
+					sizeof(struct squashfs_dir_index),
+					&index_start, &index_offset);
+
+		squashfs_get_cached_block(s, index->name, index_start,
+					index_offset, index->size + 1,
+					&index_start, &index_offset);
+
+		index->name[index->size + 1] = '\0';
+
+		if (strcmp(index->name, str) > 0)
+			break;
+
+		length = index->index;
+		*next_block = index->start_block + sblk->directory_table_start;
+	}
+
+	*next_offset = (length + *next_offset) % SQUASHFS_METADATA_SIZE;
+	return length + 3;
+}
+
+		
+static int squashfs_readdir(struct file *file, void *dirent, filldir_t filldir)
+{
+	struct inode *i = file->f_dentry->d_inode;
+	struct squashfs_sb_info *msblk = &i->i_sb->u.squashfs_sb;
+	struct squashfs_super_block *sblk = &msblk->sblk;
+	long long next_block = SQUASHFS_I(i)->start_block +
+		sblk->directory_table_start;
+	int next_offset = SQUASHFS_I(i)->offset, length = 0,
+		dir_count;
+	struct squashfs_dir_header dirh;
+	char buffer[sizeof(struct squashfs_dir_entry) + SQUASHFS_NAME_LEN + 1];
+	struct squashfs_dir_entry *dire = (struct squashfs_dir_entry *) buffer;
+
+	TRACE("Entered squashfs_readdir [%llx:%x]\n", next_block, next_offset);
+
+	while(file->f_pos < 3) {
+		char *name;
+		int size, i_ino;
+
+		if(file->f_pos == 0) {
+			name = ".";
+			size = 1;
+			i_ino = i->i_ino;
+		} else {
+			name = "..";
+			size = 2;
+			i_ino = SQUASHFS_I(i)->u.s2.parent_inode;
+		}
+		TRACE("Calling filldir(%x, %s, %d, %d, %d, %d)\n",
+				(unsigned int) dirent, name, size, (int)
+				file->f_pos, i_ino,
+				squashfs_filetype_table[1]);
+
+		if (filldir(dirent, name, size,
+				file->f_pos, i_ino,
+				squashfs_filetype_table[1]) < 0) {
+				TRACE("Filldir returned less than 0\n");
+				goto finish;
+		}
+		file->f_pos += size;
+	}
+
+	length = get_dir_index_using_offset(i->i_sb, &next_block, &next_offset,
+				SQUASHFS_I(i)->u.s2.directory_index_start,
+				SQUASHFS_I(i)->u.s2.directory_index_offset,
+				SQUASHFS_I(i)->u.s2.directory_index_count,
+				file->f_pos);
+
+	while (length < i_size_read(i)) {
+		/* read directory header */
+		if (msblk->swap) {
+			struct squashfs_dir_header sdirh;
+			
+			if (!squashfs_get_cached_block(i->i_sb, (char *) &sdirh,
+					next_block, next_offset, sizeof(sdirh),
+					&next_block, &next_offset))
+				goto failed_read;
+
+			length += sizeof(sdirh);
+			SQUASHFS_SWAP_DIR_HEADER(&dirh, &sdirh);
+		} else {
+			if (!squashfs_get_cached_block(i->i_sb, (char *) &dirh,
+					next_block, next_offset, sizeof(dirh),
+					&next_block, &next_offset))
+				goto failed_read;
+
+			length += sizeof(dirh);
+		}
+
+		dir_count = dirh.count + 1;
+		while (dir_count--) {
+			if (msblk->swap) {
+				struct squashfs_dir_entry sdire;
+				if (!squashfs_get_cached_block(i->i_sb, (char *)
+						&sdire, next_block, next_offset,
+						sizeof(sdire), &next_block,
+						&next_offset))
+					goto failed_read;
+				
+				length += sizeof(sdire);
+				SQUASHFS_SWAP_DIR_ENTRY(dire, &sdire);
+			} else {
+				if (!squashfs_get_cached_block(i->i_sb, (char *)
+						dire, next_block, next_offset,
+						sizeof(*dire), &next_block,
+						&next_offset))
+					goto failed_read;
+
+				length += sizeof(*dire);
+			}
+
+			if (!squashfs_get_cached_block(i->i_sb, dire->name,
+						next_block, next_offset,
+						dire->size + 1, &next_block,
+						&next_offset))
+				goto failed_read;
+
+			length += dire->size + 1;
+
+			if (file->f_pos >= length)
+				continue;
+
+			dire->name[dire->size + 1] = '\0';
+
+			TRACE("Calling filldir(%x, %s, %d, %d, %x:%x, %d, %d)\n",
+					(unsigned int) dirent, dire->name,
+					dire->size + 1, (int) file->f_pos,
+					dirh.start_block, dire->offset,
+					dirh.inode_number + dire->inode_number,
+					squashfs_filetype_table[dire->type]);
+
+			if (filldir(dirent, dire->name, dire->size + 1,
+					file->f_pos,
+					dirh.inode_number + dire->inode_number,
+					squashfs_filetype_table[dire->type])
+					< 0) {
+				TRACE("Filldir returned less than 0\n");
+				goto finish;
+			}
+			file->f_pos = length;
+		}
+	}
+
+finish:
+	return 0;
+
+failed_read:
+	ERROR("Unable to read directory block [%llx:%x]\n", next_block,
+		next_offset);
+	return 0;
+}
+
+
+static struct dentry *squashfs_lookup(struct inode *i, struct dentry *dentry)
+{
+	const unsigned char *name = dentry->d_name.name;
+	int len = dentry->d_name.len;
+	struct inode *inode = NULL;
+	struct squashfs_sb_info *msblk = &i->i_sb->u.squashfs_sb;
+	struct squashfs_super_block *sblk = &msblk->sblk;
+	long long next_block = SQUASHFS_I(i)->start_block +
+				sblk->directory_table_start;
+	int next_offset = SQUASHFS_I(i)->offset, length = 0,
+				dir_count;
+	struct squashfs_dir_header dirh;
+	char buffer[sizeof(struct squashfs_dir_entry) + SQUASHFS_NAME_LEN];
+	struct squashfs_dir_entry *dire = (struct squashfs_dir_entry *) buffer;
+
+	TRACE("Entered squashfs_lookup [%llx:%x]\n", next_block, next_offset);
+
+	if (len > SQUASHFS_NAME_LEN)
+		goto exit_loop;
+
+	length = get_dir_index_using_name(i->i_sb, &next_block, &next_offset,
+				SQUASHFS_I(i)->u.s2.directory_index_start,
+				SQUASHFS_I(i)->u.s2.directory_index_offset,
+				SQUASHFS_I(i)->u.s2.directory_index_count, name,
+				len);
+
+	while (length < i_size_read(i)) {
+		/* read directory header */
+		if (msblk->swap) {
+			struct squashfs_dir_header sdirh;
+			if (!squashfs_get_cached_block(i->i_sb, (char *) &sdirh,
+					next_block, next_offset, sizeof(sdirh),
+					&next_block, &next_offset))
+				goto failed_read;
+
+			length += sizeof(sdirh);
+			SQUASHFS_SWAP_DIR_HEADER(&dirh, &sdirh);
+		} else {
+			if (!squashfs_get_cached_block(i->i_sb, (char *) &dirh,
+					next_block, next_offset, sizeof(dirh),
+					&next_block, &next_offset))
+				goto failed_read;
+
+			length += sizeof(dirh);
+		}
+
+		dir_count = dirh.count + 1;
+		while (dir_count--) {
+			if (msblk->swap) {
+				struct squashfs_dir_entry sdire;
+				if (!squashfs_get_cached_block(i->i_sb, (char *)
+						&sdire, next_block,next_offset,
+						sizeof(sdire), &next_block,
+						&next_offset))
+					goto failed_read;
+				
+				length += sizeof(sdire);
+				SQUASHFS_SWAP_DIR_ENTRY(dire, &sdire);
+			} else {
+				if (!squashfs_get_cached_block(i->i_sb, (char *)
+						dire, next_block,next_offset,
+						sizeof(*dire), &next_block,
+						&next_offset))
+					goto failed_read;
+
+				length += sizeof(*dire);
+			}
+
+			if (!squashfs_get_cached_block(i->i_sb, dire->name,
+					next_block, next_offset, dire->size + 1,
+					&next_block, &next_offset))
+				goto failed_read;
+
+			length += dire->size + 1;
+
+			if (name[0] < dire->name[0])
+				goto exit_loop;
+
+			if ((len == dire->size + 1) && !strncmp(name,
+						dire->name, len)) {
+				squashfs_inode_t ino =
+					SQUASHFS_MKINODE(dirh.start_block,
+					dire->offset);
+
+				TRACE("calling squashfs_iget for directory "
+					"entry %s, inode %x:%x, %d\n", name,
+					dirh.start_block, dire->offset,
+					dirh.inode_number + dire->inode_number);
+
+				inode = (msblk->iget)(i->i_sb, ino);
+
+				goto exit_loop;
+			}
+		}
+	}
+
+exit_loop:
+	d_add(dentry, inode);
+	return ERR_PTR(0);
+
+failed_read:
+	ERROR("Unable to read directory block [%llx:%x]\n", next_block,
+		next_offset);
+	goto exit_loop;
+}
+
+
+static void squashfs_put_super(struct super_block *s)
+{
+	int i;
+
+		struct squashfs_sb_info *sbi = &s->u.squashfs_sb;
+		if (sbi->block_cache)
+			for (i = 0; i < SQUASHFS_CACHED_BLKS; i++)
+				if (sbi->block_cache[i].block !=
+							SQUASHFS_INVALID_BLK)
+					kfree(sbi->block_cache[i].data);
+		if (sbi->fragment)
+			for (i = 0; i < SQUASHFS_CACHED_FRAGMENTS; i++) 
+				SQUASHFS_FREE(sbi->fragment[i].data);
+		kfree(sbi->fragment);
+		kfree(sbi->block_cache);
+		kfree(sbi->read_data);
+		kfree(sbi->read_page);
+		kfree(sbi->uid);
+		kfree(sbi->fragment_index);
+		kfree(sbi->fragment_index_2);
+		kfree(sbi->meta_index);
+		vfree(sbi->stream.workspace);
+		sbi->block_cache = NULL;
+		sbi->uid = NULL;
+		sbi->read_data = NULL;
+		sbi->read_page = NULL;
+		sbi->fragment = NULL;
+		sbi->fragment_index = NULL;
+		sbi->fragment_index_2 = NULL;
+		sbi->meta_index = NULL;
+		sbi->stream.workspace = NULL;
+}
+
+
+static int __init init_squashfs_fs(void)
+{
+
+	printk(KERN_INFO "squashfs: version 3.1 (2006/08/15) "
+		"Phillip Lougher\n");
+
+	return register_filesystem(&squashfs_fs_type);
+}
+
+
+static void __exit exit_squashfs_fs(void)
+{
+	unregister_filesystem(&squashfs_fs_type);
+}
+
+
+EXPORT_NO_SYMBOLS;
+
+module_init(init_squashfs_fs);
+module_exit(exit_squashfs_fs);
+MODULE_DESCRIPTION("squashfs 3.1, a compressed read-only filesystem");
+MODULE_AUTHOR("Phillip Lougher <phillip@lougher.demon.co.uk>");
+MODULE_LICENSE("GPL");

SQUASHFS/squashfs-tools-4.4/kernel/kernel-2.4/fs/squashfs/squashfs.h

+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2002, 2003, 2004, 2005, 2006
+ * Phillip Lougher <phillip@lougher.demon.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2,
+ * or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * squashfs.h
+ */
+
+#ifdef CONFIG_SQUASHFS_1_0_COMPATIBILITY
+#undef CONFIG_SQUASHFS_1_0_COMPATIBILITY
+#endif
+#ifdef SQUASHFS_TRACE
+#define TRACE(s, args...)	printk(KERN_NOTICE "SQUASHFS: "s, ## args)
+#else
+#define TRACE(s, args...)	{}
+#endif
+
+#define ERROR(s, args...)	printk(KERN_ERR "SQUASHFS error: "s, ## args)
+
+#define SERROR(s, args...)	do { \
+				if (!silent) \
+				printk(KERN_ERR "SQUASHFS error: "s, ## args);\
+				} while(0)
+
+#define WARNING(s, args...)	printk(KERN_WARNING "SQUASHFS: "s, ## args)
+
+#define SQUASHFS_I(INO)			(&INO->u.squashfs_i)
+
+#define i_size_read(INO)		(INO->i_size)
+
+#if defined(CONFIG_SQUASHFS_1_0_COMPATIBILITY ) || defined(CONFIG_SQUASHFS_2_0_COMPATIBILITY)
+#define SQSH_EXTERN
+extern unsigned int squashfs_read_data(struct super_block *s, char *buffer,
+				long long index, unsigned int length,
+				long long *next_index);
+extern int squashfs_get_cached_block(struct super_block *s, char *buffer,
+				long long block, unsigned int offset,
+				int length, long long *next_block,
+				unsigned int *next_offset);
+extern void release_cached_fragment(struct squashfs_sb_info *msblk, struct
+					squashfs_fragment_cache *fragment);
+extern struct squashfs_fragment_cache *get_cached_fragment(struct super_block
+					*s, long long start_block,
+					int length);
+extern struct address_space_operations squashfs_symlink_aops;
+extern struct address_space_operations squashfs_aops;
+extern struct address_space_operations squashfs_aops_4K;
+extern struct file_operations squashfs_dir_ops;
+extern struct inode_operations squashfs_dir_inode_ops;
+#else
+#define SQSH_EXTERN static
+#endif
+
+#ifdef CONFIG_SQUASHFS_1_0_COMPATIBILITY
+extern int squashfs_1_0_supported(struct squashfs_sb_info *msblk);
+#else
+static inline int squashfs_1_0_supported(struct squashfs_sb_info *msblk)
+{
+	return 0;
+}
+#endif
+
+#ifdef CONFIG_SQUASHFS_2_0_COMPATIBILITY
+extern int squashfs_2_0_supported(struct squashfs_sb_info *msblk);
+#else
+static inline int squashfs_2_0_supported(struct squashfs_sb_info *msblk)
+{
+	return 0;
+}
+#endif

SQUASHFS/squashfs-tools-4.4/kernel/kernel-2.4/fs/squashfs/squashfs2_0.c

+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2002, 2003, 2004, 2005, 2006
+ * Phillip Lougher <phillip@lougher.demon.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2,
+ * or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * squashfs2_0.c
+ */
+
+#include <linux/types.h>
+#include <linux/squashfs_fs.h>
+#include <linux/module.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/zlib.h>
+#include <linux/fs.h>
+#include <linux/smp_lock.h>
+#include <linux/locks.h>
+#include <linux/init.h>
+#include <linux/dcache.h>
+#include <linux/wait.h>
+#include <linux/zlib.h>
+#include <linux/blkdev.h>
+#include <linux/vmalloc.h>
+#include <asm/uaccess.h>
+#include <asm/semaphore.h>
+#include "squashfs.h"
+
+static int squashfs_readdir_2(struct file *file, void *dirent, filldir_t filldir);
+static struct dentry *squashfs_lookup_2(struct inode *i, struct dentry *dentry);
+
+static struct file_operations squashfs_dir_ops_2 = {
+	.read = generic_read_dir,
+	.readdir = squashfs_readdir_2
+};
+
+static struct inode_operations squashfs_dir_inode_ops_2 = {
+	.lookup = squashfs_lookup_2
+};
+
+static unsigned char squashfs_filetype_table[] = {
+	DT_UNKNOWN, DT_DIR, DT_REG, DT_LNK, DT_BLK, DT_CHR, DT_FIFO, DT_SOCK
+};
+
+static int read_fragment_index_table_2(struct super_block *s)
+{
+	struct squashfs_sb_info *msblk = &s->u.squashfs_sb;
+	struct squashfs_super_block *sblk = &msblk->sblk;
+
+	if (!(msblk->fragment_index_2 = kmalloc(SQUASHFS_FRAGMENT_INDEX_BYTES_2
+					(sblk->fragments), GFP_KERNEL))) {
+		ERROR("Failed to allocate uid/gid table\n");
+		return 0;
+	}
+   
+	if (SQUASHFS_FRAGMENT_INDEX_BYTES_2(sblk->fragments) &&
+					!squashfs_read_data(s, (char *)
+					msblk->fragment_index_2,
+					sblk->fragment_table_start,
+					SQUASHFS_FRAGMENT_INDEX_BYTES_2
+					(sblk->fragments) |
+					SQUASHFS_COMPRESSED_BIT_BLOCK, NULL)) {
+		ERROR("unable to read fragment index table\n");
+		return 0;
+	}
+
+	if (msblk->swap) {
+		int i;
+		unsigned int fragment;
+
+		for (i = 0; i < SQUASHFS_FRAGMENT_INDEXES_2(sblk->fragments);
+									i++) {
+			SQUASHFS_SWAP_FRAGMENT_INDEXES_2((&fragment),
+						&msblk->fragment_index_2[i], 1);
+			msblk->fragment_index_2[i] = fragment;
+		}
+	}
+
+	return 1;
+}
+
+
+static int get_fragment_location_2(struct super_block *s, unsigned int fragment,
+				long long *fragment_start_block,
+				unsigned int *fragment_size)
+{
+	struct squashfs_sb_info *msblk = &s->u.squashfs_sb;
+	long long start_block =
+		msblk->fragment_index_2[SQUASHFS_FRAGMENT_INDEX_2(fragment)];
+	int offset = SQUASHFS_FRAGMENT_INDEX_OFFSET_2(fragment);
+	struct squashfs_fragment_entry_2 fragment_entry;
+
+	if (msblk->swap) {
+		struct squashfs_fragment_entry_2 sfragment_entry;
+
+		if (!squashfs_get_cached_block(s, (char *) &sfragment_entry,
+					start_block, offset,
+					sizeof(sfragment_entry), &start_block,
+					&offset))
+			goto out;
+		SQUASHFS_SWAP_FRAGMENT_ENTRY_2(&fragment_entry, &sfragment_entry);
+	} else
+		if (!squashfs_get_cached_block(s, (char *) &fragment_entry,
+					start_block, offset,
+					sizeof(fragment_entry), &start_block,
+					&offset))
+			goto out;
+
+	*fragment_start_block = fragment_entry.start_block;
+	*fragment_size = fragment_entry.size;
+
+	return 1;
+
+out:
+	return 0;
+}
+
+
+static struct inode *squashfs_new_inode(struct super_block *s,
+		struct squashfs_base_inode_header_2 *inodeb, unsigned int ino)
+{
+	struct squashfs_sb_info *msblk = &s->u.squashfs_sb;
+	struct squashfs_super_block *sblk = &msblk->sblk;
+	struct inode *i = new_inode(s);
+
+	if (i) {
+		i->i_ino = ino;
+		i->i_mtime = sblk->mkfs_time;
+		i->i_atime = sblk->mkfs_time;
+		i->i_ctime = sblk->mkfs_time;
+		i->i_uid = msblk->uid[inodeb->uid];
+		i->i_mode = inodeb->mode;
+		i->i_nlink = 1;
+		i->i_size = 0;
+		if (inodeb->guid == SQUASHFS_GUIDS)
+			i->i_gid = i->i_uid;
+		else
+			i->i_gid = msblk->guid[inodeb->guid];
+	}
+
+	return i;
+}
+
+
+static struct inode *squashfs_iget_2(struct super_block *s, squashfs_inode_t inode)
+{
+	struct inode *i;
+	struct squashfs_sb_info *msblk = &s->u.squashfs_sb;
+	struct squashfs_super_block *sblk = &msblk->sblk;
+	unsigned int block = SQUASHFS_INODE_BLK(inode) +
+		sblk->inode_table_start;
+	unsigned int offset = SQUASHFS_INODE_OFFSET(inode);
+	unsigned int ino = SQUASHFS_MK_VFS_INODE(block
+		- sblk->inode_table_start, offset);
+	long long next_block;
+	unsigned int next_offset;
+	union squashfs_inode_header_2 id, sid;
+	struct squashfs_base_inode_header_2 *inodeb = &id.base,
+					  *sinodeb = &sid.base;
+
+	TRACE("Entered squashfs_iget\n");
+
+	if (msblk->swap) {
+		if (!squashfs_get_cached_block(s, (char *) sinodeb, block,
+					offset, sizeof(*sinodeb), &next_block,
+					&next_offset))
+			goto failed_read;
+		SQUASHFS_SWAP_BASE_INODE_HEADER_2(inodeb, sinodeb,
+					sizeof(*sinodeb));
+	} else
+		if (!squashfs_get_cached_block(s, (char *) inodeb, block,
+					offset, sizeof(*inodeb), &next_block,
+					&next_offset))
+			goto failed_read;
+
+	switch(inodeb->inode_type) {
+		case SQUASHFS_FILE_TYPE: {
+			struct squashfs_reg_inode_header_2 *inodep = &id.reg;
+			struct squashfs_reg_inode_header_2 *sinodep = &sid.reg;
+			long long frag_blk;
+			unsigned int frag_size;
+				
+			if (msblk->swap) {
+				if (!squashfs_get_cached_block(s, (char *)
+						sinodep, block, offset,
+						sizeof(*sinodep), &next_block,
+						&next_offset))
+					goto failed_read;
+				SQUASHFS_SWAP_REG_INODE_HEADER_2(inodep, sinodep);
+			} else
+				if (!squashfs_get_cached_block(s, (char *)
+						inodep, block, offset,
+						sizeof(*inodep), &next_block,
+						&next_offset))
+					goto failed_read;
+
+			frag_blk = SQUASHFS_INVALID_BLK;
+			if (inodep->fragment != SQUASHFS_INVALID_FRAG &&
+					!get_fragment_location_2(s,
+					inodep->fragment, &frag_blk, &frag_size))
+				goto failed_read;
+				
+			if((i = squashfs_new_inode(s, inodeb, ino)) == NULL)
+				goto failed_read1;
+
+			i->i_size = inodep->file_size;
+			i->i_fop = &generic_ro_fops;
+			i->i_mode |= S_IFREG;
+			i->i_mtime = inodep->mtime;
+			i->i_atime = inodep->mtime;
+			i->i_ctime = inodep->mtime;
+			i->i_blocks = ((i->i_size - 1) >> 9) + 1;
+			i->i_blksize = PAGE_CACHE_SIZE;
+			SQUASHFS_I(i)->u.s1.fragment_start_block = frag_blk;
+			SQUASHFS_I(i)->u.s1.fragment_size = frag_size;
+			SQUASHFS_I(i)->u.s1.fragment_offset = inodep->offset;
+			SQUASHFS_I(i)->start_block = inodep->start_block;
+			SQUASHFS_I(i)->u.s1.block_list_start = next_block;
+			SQUASHFS_I(i)->offset = next_offset;
+			if (sblk->block_size > 4096)
+				i->i_data.a_ops = &squashfs_aops;
+			else
+				i->i_data.a_ops = &squashfs_aops_4K;
+
+			TRACE("File inode %x:%x, start_block %x, "
+					"block_list_start %llx, offset %x\n",
+					SQUASHFS_INODE_BLK(inode), offset,
+					inodep->start_block, next_block,
+					next_offset);
+			break;
+		}
+		case SQUASHFS_DIR_TYPE: {
+			struct squashfs_dir_inode_header_2 *inodep = &id.dir;
+			struct squashfs_dir_inode_header_2 *sinodep = &sid.dir;
+
+			if (msblk->swap) {
+				if (!squashfs_get_cached_block(s, (char *)
+						sinodep, block, offset,
+						sizeof(*sinodep), &next_block,
+						&next_offset))
+					goto failed_read;
+				SQUASHFS_SWAP_DIR_INODE_HEADER_2(inodep, sinodep);
+			} else
+				if (!squashfs_get_cached_block(s, (char *)
+						inodep, block, offset,
+						sizeof(*inodep), &next_block,
+						&next_offset))
+					goto failed_read;
+
+			if((i = squashfs_new_inode(s, inodeb, ino)) == NULL)
+				goto failed_read1;
+
+			i->i_size = inodep->file_size;
+			i->i_op = &squashfs_dir_inode_ops_2;
+			i->i_fop = &squashfs_dir_ops_2;
+			i->i_mode |= S_IFDIR;
+			i->i_mtime = inodep->mtime;
+			i->i_atime = inodep->mtime;
+			i->i_ctime = inodep->mtime;
+			SQUASHFS_I(i)->start_block = inodep->start_block;
+			SQUASHFS_I(i)->offset = inodep->offset;
+			SQUASHFS_I(i)->u.s2.directory_index_count = 0;
+			SQUASHFS_I(i)->u.s2.parent_inode = 0;
+
+			TRACE("Directory inode %x:%x, start_block %x, offset "
+					"%x\n", SQUASHFS_INODE_BLK(inode),
+					offset, inodep->start_block,
+					inodep->offset);
+			break;
+		}
+		case SQUASHFS_LDIR_TYPE: {
+			struct squashfs_ldir_inode_header_2 *inodep = &id.ldir;
+			struct squashfs_ldir_inode_header_2 *sinodep = &sid.ldir;
+
+			if (msblk->swap) {
+				if (!squashfs_get_cached_block(s, (char *)
+						sinodep, block, offset,
+						sizeof(*sinodep), &next_block,
+						&next_offset))
+					goto failed_read;
+				SQUASHFS_SWAP_LDIR_INODE_HEADER_2(inodep,
+						sinodep);
+			} else
+				if (!squashfs_get_cached_block(s, (char *)
+						inodep, block, offset,
+						sizeof(*inodep), &next_block,
+						&next_offset))
+					goto failed_read;
+
+			if((i = squashfs_new_inode(s, inodeb, ino)) == NULL)
+				goto failed_read1;
+
+			i->i_size = inodep->file_size;
+			i->i_op = &squashfs_dir_inode_ops_2;
+			i->i_fop = &squashfs_dir_ops_2;
+			i->i_mode |= S_IFDIR;
+			i->i_mtime = inodep->mtime;
+			i->i_atime = inodep->mtime;
+			i->i_ctime = inodep->mtime;
+			SQUASHFS_I(i)->start_block = inodep->start_block;
+			SQUASHFS_I(i)->offset = inodep->offset;
+			SQUASHFS_I(i)->u.s2.directory_index_start = next_block;
+			SQUASHFS_I(i)->u.s2.directory_index_offset =
+								next_offset;
+			SQUASHFS_I(i)->u.s2.directory_index_count =
+								inodep->i_count;
+			SQUASHFS_I(i)->u.s2.parent_inode = 0;
+
+			TRACE("Long directory inode %x:%x, start_block %x, "
+					"offset %x\n",
+					SQUASHFS_INODE_BLK(inode), offset,
+					inodep->start_block, inodep->offset);
+			break;
+		}
+		case SQUASHFS_SYMLINK_TYPE: {
+			struct squashfs_symlink_inode_header_2 *inodep =
+								&id.symlink;
+			struct squashfs_symlink_inode_header_2 *sinodep =
+								&sid.symlink;
+	
+			if (msblk->swap) {
+				if (!squashfs_get_cached_block(s, (char *)
+						sinodep, block, offset,
+						sizeof(*sinodep), &next_block,
+						&next_offset))
+					goto failed_read;
+				SQUASHFS_SWAP_SYMLINK_INODE_HEADER_2(inodep,
+								sinodep);
+			} else
+				if (!squashfs_get_cached_block(s, (char *)
+						inodep, block, offset,
+						sizeof(*inodep), &next_block,
+						&next_offset))
+					goto failed_read;
+
+			if((i = squashfs_new_inode(s, inodeb, ino)) == NULL)
+				goto failed_read1;
+
+			i->i_size = inodep->symlink_size;
+			i->i_op = &page_symlink_inode_operations;
+			i->i_data.a_ops = &squashfs_symlink_aops;
+			i->i_mode |= S_IFLNK;
+			SQUASHFS_I(i)->start_block = next_block;
+			SQUASHFS_I(i)->offset = next_offset;
+
+			TRACE("Symbolic link inode %x:%x, start_block %llx, "
+					"offset %x\n",
+					SQUASHFS_INODE_BLK(inode), offset,
+					next_block, next_offset);
+			break;
+		 }
+		 case SQUASHFS_BLKDEV_TYPE:
+		 case SQUASHFS_CHRDEV_TYPE: {
+			struct squashfs_dev_inode_header_2 *inodep = &id.dev;
+			struct squashfs_dev_inode_header_2 *sinodep = &sid.dev;
+
+			if (msblk->swap) {
+				if (!squashfs_get_cached_block(s, (char *)
+						sinodep, block, offset,
+						sizeof(*sinodep), &next_block,
+						&next_offset))
+					goto failed_read;
+				SQUASHFS_SWAP_DEV_INODE_HEADER_2(inodep, sinodep);
+			} else	
+				if (!squashfs_get_cached_block(s, (char *)
+						inodep, block, offset,
+						sizeof(*inodep), &next_block,
+						&next_offset))
+					goto failed_read;
+
+			if ((i = squashfs_new_inode(s, inodeb, ino)) == NULL)
+				goto failed_read1;
+
+			i->i_mode |= (inodeb->inode_type ==
+					SQUASHFS_CHRDEV_TYPE) ?  S_IFCHR :
+					S_IFBLK;
+			init_special_inode(i, i->i_mode, inodep->rdev);
+
+			TRACE("Device inode %x:%x, rdev %x\n",
+					SQUASHFS_INODE_BLK(inode), offset,
+					inodep->rdev);
+			break;
+		 }
+		 case SQUASHFS_FIFO_TYPE:
+		 case SQUASHFS_SOCKET_TYPE: {
+			if ((i = squashfs_new_inode(s, inodeb, ino)) == NULL)
+				goto failed_read1;
+
+			i->i_mode |= (inodeb->inode_type == SQUASHFS_FIFO_TYPE)
+							? S_IFIFO : S_IFSOCK;
+			init_special_inode(i, i->i_mode, 0);
+			break;
+		 }
+		 default:
+			ERROR("Unknown inode type %d in squashfs_iget!\n",
+					inodeb->inode_type);
+			goto failed_read1;
+	}
+	
+	insert_inode_hash(i);
+	return i;
+
+failed_read:
+	ERROR("Unable to read inode [%x:%x]\n", block, offset);
+
+failed_read1:
+	return NULL;
+}
+
+
+static int get_dir_index_using_offset(struct super_block *s, long long 
+				*next_block, unsigned int *next_offset,
+				long long index_start,
+				unsigned int index_offset, int i_count,
+				long long f_pos)
+{
+	struct squashfs_sb_info *msblk = &s->u.squashfs_sb;
+	struct squashfs_super_block *sblk = &msblk->sblk;
+	int i, length = 0;
+	struct squashfs_dir_index_2 index;
+
+	TRACE("Entered get_dir_index_using_offset, i_count %d, f_pos %d\n",
+					i_count, (unsigned int) f_pos);
+
+	if (f_pos == 0)
+		goto finish;
+
+	for (i = 0; i < i_count; i++) {
+		if (msblk->swap) {
+			struct squashfs_dir_index_2 sindex;
+			squashfs_get_cached_block(s, (char *) &sindex,
+					index_start, index_offset,
+					sizeof(sindex), &index_start,
+					&index_offset);
+			SQUASHFS_SWAP_DIR_INDEX_2(&index, &sindex);
+		} else
+			squashfs_get_cached_block(s, (char *) &index,
+					index_start, index_offset,
+					sizeof(index), &index_start,
+					&index_offset);
+
+		if (index.index > f_pos)
+			break;
+
+		squashfs_get_cached_block(s, NULL, index_start, index_offset,
+					index.size + 1, &index_start,
+					&index_offset);
+
+		length = index.index;
+		*next_block = index.start_block + sblk->directory_table_start;
+	}
+
+	*next_offset = (length + *next_offset) % SQUASHFS_METADATA_SIZE;
+
+finish:
+	return length;
+}
+
+
+static int get_dir_index_using_name(struct super_block *s, long long
+				*next_block, unsigned int *next_offset,
+				long long index_start,
+				unsigned int index_offset, int i_count,
+				const char *name, int size)
+{
+	struct squashfs_sb_info *msblk = &s->u.squashfs_sb;
+	struct squashfs_super_block *sblk = &msblk->sblk;
+	int i, length = 0;
+	char buffer[sizeof(struct squashfs_dir_index_2) + SQUASHFS_NAME_LEN + 1];
+	struct squashfs_dir_index_2 *index = (struct squashfs_dir_index_2 *) buffer;
+	char str[SQUASHFS_NAME_LEN + 1];
+
+	TRACE("Entered get_dir_index_using_name, i_count %d\n", i_count);
+
+	strncpy(str, name, size);
+	str[size] = '\0';
+
+	for (i = 0; i < i_count; i++) {
+		if (msblk->swap) {
+			struct squashfs_dir_index_2 sindex;
+			squashfs_get_cached_block(s, (char *) &sindex,
+					index_start, index_offset,
+					sizeof(sindex), &index_start,
+					&index_offset);
+			SQUASHFS_SWAP_DIR_INDEX_2(index, &sindex);
+		} else
+			squashfs_get_cached_block(s, (char *) index,
+					index_start, index_offset,
+					sizeof(struct squashfs_dir_index_2),
+					&index_start, &index_offset);
+
+		squashfs_get_cached_block(s, index->name, index_start,
+					index_offset, index->size + 1,
+					&index_start, &index_offset);
+
+		index->name[index->size + 1] = '\0';
+
+		if (strcmp(index->name, str) > 0)
+			break;
+
+		length = index->index;
+		*next_block = index->start_block + sblk->directory_table_start;
+	}
+
+	*next_offset = (length + *next_offset) % SQUASHFS_METADATA_SIZE;
+	return length;
+}
+
+		
+static int squashfs_readdir_2(struct file *file, void *dirent, filldir_t filldir)
+{
+	struct inode *i = file->f_dentry->d_inode;
+	struct squashfs_sb_info *msblk = &i->i_sb->u.squashfs_sb;
+	struct squashfs_super_block *sblk = &msblk->sblk;
+	long long next_block = SQUASHFS_I(i)->start_block +
+		sblk->directory_table_start;
+	int next_offset = SQUASHFS_I(i)->offset, length = 0,
+		dir_count;
+	struct squashfs_dir_header_2 dirh;
+	char buffer[sizeof(struct squashfs_dir_entry_2) + SQUASHFS_NAME_LEN + 1];
+	struct squashfs_dir_entry_2 *dire = (struct squashfs_dir_entry_2 *) buffer;
+
+	TRACE("Entered squashfs_readdir_2 [%llx:%x]\n", next_block, next_offset);
+
+	length = get_dir_index_using_offset(i->i_sb, &next_block, &next_offset,
+				SQUASHFS_I(i)->u.s2.directory_index_start,
+				SQUASHFS_I(i)->u.s2.directory_index_offset,
+				SQUASHFS_I(i)->u.s2.directory_index_count,
+				file->f_pos);
+
+	while (length < i_size_read(i)) {
+		/* read directory header */
+		if (msblk->swap) {
+			struct squashfs_dir_header_2 sdirh;
+			
+			if (!squashfs_get_cached_block(i->i_sb, (char *) &sdirh,
+					next_block, next_offset, sizeof(sdirh),
+					&next_block, &next_offset))
+				goto failed_read;
+
+			length += sizeof(sdirh);
+			SQUASHFS_SWAP_DIR_HEADER_2(&dirh, &sdirh);
+		} else {
+			if (!squashfs_get_cached_block(i->i_sb, (char *) &dirh,
+					next_block, next_offset, sizeof(dirh),
+					&next_block, &next_offset))
+				goto failed_read;
+
+			length += sizeof(dirh);
+		}
+
+		dir_count = dirh.count + 1;
+		while (dir_count--) {
+			if (msblk->swap) {
+				struct squashfs_dir_entry_2 sdire;
+				if (!squashfs_get_cached_block(i->i_sb, (char *)
+						&sdire, next_block, next_offset,
+						sizeof(sdire), &next_block,
+						&next_offset))
+					goto failed_read;
+				
+				length += sizeof(sdire);
+				SQUASHFS_SWAP_DIR_ENTRY_2(dire, &sdire);
+			} else {
+				if (!squashfs_get_cached_block(i->i_sb, (char *)
+						dire, next_block, next_offset,
+						sizeof(*dire), &next_block,
+						&next_offset))
+					goto failed_read;
+
+				length += sizeof(*dire);
+			}
+
+			if (!squashfs_get_cached_block(i->i_sb, dire->name,
+						next_block, next_offset,
+						dire->size + 1, &next_block,
+						&next_offset))
+				goto failed_read;
+
+			length += dire->size + 1;
+
+			if (file->f_pos >= length)
+				continue;
+
+			dire->name[dire->size + 1] = '\0';
+
+			TRACE("Calling filldir(%x, %s, %d, %d, %x:%x, %d)\n",
+					(unsigned int) dirent, dire->name,
+					dire->size + 1, (int) file->f_pos,
+					dirh.start_block, dire->offset,
+					squashfs_filetype_table[dire->type]);
+
+			if (filldir(dirent, dire->name, dire->size + 1,
+					file->f_pos, SQUASHFS_MK_VFS_INODE(
+					dirh.start_block, dire->offset),
+					squashfs_filetype_table[dire->type])
+					< 0) {
+				TRACE("Filldir returned less than 0\n");
+				goto finish;
+			}
+			file->f_pos = length;
+		}
+	}
+
+finish:
+	return 0;
+
+failed_read:
+	ERROR("Unable to read directory block [%llx:%x]\n", next_block,
+		next_offset);
+	return 0;
+}
+
+
+static struct dentry *squashfs_lookup_2(struct inode *i, struct dentry *dentry)
+{
+	const unsigned char *name = dentry->d_name.name;
+	int len = dentry->d_name.len;
+	struct inode *inode = NULL;
+	struct squashfs_sb_info *msblk = &i->i_sb->u.squashfs_sb;
+	struct squashfs_super_block *sblk = &msblk->sblk;
+	long long next_block = SQUASHFS_I(i)->start_block +
+				sblk->directory_table_start;
+	int next_offset = SQUASHFS_I(i)->offset, length = 0,
+				dir_count;
+	struct squashfs_dir_header_2 dirh;
+	char buffer[sizeof(struct squashfs_dir_entry_2) + SQUASHFS_NAME_LEN];
+	struct squashfs_dir_entry_2 *dire = (struct squashfs_dir_entry_2 *) buffer;
+	int sorted = sblk->s_major == 2 && sblk->s_minor >= 1;
+
+	TRACE("Entered squashfs_lookup [%llx:%x]\n", next_block, next_offset);
+
+	if (len > SQUASHFS_NAME_LEN)
+		goto exit_loop;
+
+	length = get_dir_index_using_name(i->i_sb, &next_block, &next_offset,
+				SQUASHFS_I(i)->u.s2.directory_index_start,
+				SQUASHFS_I(i)->u.s2.directory_index_offset,
+				SQUASHFS_I(i)->u.s2.directory_index_count, name,
+				len);
+
+	while (length < i_size_read(i)) {
+		/* read directory header */
+		if (msblk->swap) {
+			struct squashfs_dir_header_2 sdirh;
+			if (!squashfs_get_cached_block(i->i_sb, (char *) &sdirh,
+					next_block, next_offset, sizeof(sdirh),
+					&next_block, &next_offset))
+				goto failed_read;
+
+			length += sizeof(sdirh);
+			SQUASHFS_SWAP_DIR_HEADER_2(&dirh, &sdirh);
+		} else {
+			if (!squashfs_get_cached_block(i->i_sb, (char *) &dirh,
+					next_block, next_offset, sizeof(dirh),
+					&next_block, &next_offset))
+				goto failed_read;
+
+			length += sizeof(dirh);
+		}
+
+		dir_count = dirh.count + 1;
+		while (dir_count--) {
+			if (msblk->swap) {
+				struct squashfs_dir_entry_2 sdire;
+				if (!squashfs_get_cached_block(i->i_sb, (char *)
+						&sdire, next_block,next_offset,
+						sizeof(sdire), &next_block,
+						&next_offset))
+					goto failed_read;
+				
+				length += sizeof(sdire);
+				SQUASHFS_SWAP_DIR_ENTRY_2(dire, &sdire);
+			} else {
+				if (!squashfs_get_cached_block(i->i_sb, (char *)
+						dire, next_block,next_offset,
+						sizeof(*dire), &next_block,
+						&next_offset))
+					goto failed_read;
+
+				length += sizeof(*dire);
+			}
+
+			if (!squashfs_get_cached_block(i->i_sb, dire->name,
+					next_block, next_offset, dire->size + 1,
+					&next_block, &next_offset))
+				goto failed_read;
+
+			length += dire->size + 1;
+
+			if (sorted && name[0] < dire->name[0])
+				goto exit_loop;
+
+			if ((len == dire->size + 1) && !strncmp(name,
+						dire->name, len)) {
+				squashfs_inode_t ino =
+					SQUASHFS_MKINODE(dirh.start_block,
+					dire->offset);
+
+				TRACE("calling squashfs_iget for directory "
+					"entry %s, inode %x:%x, %d\n", name,
+					dirh.start_block, dire->offset, ino);
+
+				inode = (msblk->iget)(i->i_sb, ino);
+
+				goto exit_loop;
+			}
+		}
+	}
+
+exit_loop:
+	d_add(dentry, inode);
+	return ERR_PTR(0);
+
+failed_read:
+	ERROR("Unable to read directory block [%llx:%x]\n", next_block,
+		next_offset);
+	goto exit_loop;
+}
+
+
+int squashfs_2_0_supported(struct squashfs_sb_info *msblk)
+{
+	struct squashfs_super_block *sblk = &msblk->sblk;
+
+	msblk->iget = squashfs_iget_2;
+	msblk->read_fragment_index_table = read_fragment_index_table_2;
+
+	sblk->bytes_used = sblk->bytes_used_2;
+	sblk->uid_start = sblk->uid_start_2;
+	sblk->guid_start = sblk->guid_start_2;
+	sblk->inode_table_start = sblk->inode_table_start_2;
+	sblk->directory_table_start = sblk->directory_table_start_2;
+	sblk->fragment_table_start = sblk->fragment_table_start_2;
+
+	return 1;
+}

SQUASHFS/squashfs-tools-4.4/kernel/kernel-2.4/include/linux/squashfs_fs.h

+#ifndef SQUASHFS_FS
+#define SQUASHFS_FS
+
+/*
+ * Squashfs
+ *
+ * Copyright (c) 2002, 2003, 2004, 2005, 2006
+ * Phillip Lougher <phillip@lougher.demon.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2,
+ * or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * squashfs_fs.h
+ */
+
+#ifndef CONFIG_SQUASHFS_2_0_COMPATIBILITY
+#define CONFIG_SQUASHFS_2_0_COMPATIBILITY
+#endif
+
+#ifdef CONFIG_SQUASHFS_VMALLOC
+#define SQUASHFS_ALLOC(a)		vmalloc(a)
+#define SQUASHFS_FREE(a)		vfree(a)
+#else
+#define SQUASHFS_ALLOC(a)		kmalloc(a, GFP_KERNEL)
+#define SQUASHFS_FREE(a)		kfree(a)
+#endif
+#ifdef CONFIG_SQUASHFS_FRAGMENT_CACHE_SIZE
+#define SQUASHFS_CACHED_FRAGMENTS	CONFIG_SQUASHFS_FRAGMENT_CACHE_SIZE
+#else
+#define SQUASHFS_CACHED_FRAGMENTS	3
+#endif
+#define SQUASHFS_MAJOR			3
+#define SQUASHFS_MINOR			0
+#define SQUASHFS_MAGIC			0x73717368
+#define SQUASHFS_MAGIC_SWAP		0x68737173
+#define SQUASHFS_START			0
+
+/* size of metadata (inode and directory) blocks */
+#define SQUASHFS_METADATA_SIZE		8192
+#define SQUASHFS_METADATA_LOG		13
+
+/* default size of data blocks */
+#define SQUASHFS_FILE_SIZE		65536
+#define SQUASHFS_FILE_LOG		16
+
+#define SQUASHFS_FILE_MAX_SIZE		65536
+
+/* Max number of uids and gids */
+#define SQUASHFS_UIDS			256
+#define SQUASHFS_GUIDS			255
+
+/* Max length of filename (not 255) */
+#define SQUASHFS_NAME_LEN		256
+
+#define SQUASHFS_INVALID		((long long) 0xffffffffffff)
+#define SQUASHFS_INVALID_FRAG		((unsigned int) 0xffffffff)
+#define SQUASHFS_INVALID_BLK		((long long) -1)
+#define SQUASHFS_USED_BLK		((long long) -2)
+
+/* Filesystem flags */
+#define SQUASHFS_NOI			0
+#define SQUASHFS_NOD			1
+#define SQUASHFS_CHECK			2
+#define SQUASHFS_NOF			3
+#define SQUASHFS_NO_FRAG		4
+#define SQUASHFS_ALWAYS_FRAG		5
+#define SQUASHFS_DUPLICATE		6
+
+#define SQUASHFS_BIT(flag, bit)		((flag >> bit) & 1)
+
+#define SQUASHFS_UNCOMPRESSED_INODES(flags)	SQUASHFS_BIT(flags, \
+						SQUASHFS_NOI)
+
+#define SQUASHFS_UNCOMPRESSED_DATA(flags)	SQUASHFS_BIT(flags, \
+						SQUASHFS_NOD)
+
+#define SQUASHFS_UNCOMPRESSED_FRAGMENTS(flags)	SQUASHFS_BIT(flags, \
+						SQUASHFS_NOF)
+
+#define SQUASHFS_NO_FRAGMENTS(flags)		SQUASHFS_BIT(flags, \
+						SQUASHFS_NO_FRAG)
+
+#define SQUASHFS_ALWAYS_FRAGMENTS(flags)	SQUASHFS_BIT(flags, \
+						SQUASHFS_ALWAYS_FRAG)
+
+#define SQUASHFS_DUPLICATES(flags)		SQUASHFS_BIT(flags, \
+						SQUASHFS_DUPLICATE)
+
+#define SQUASHFS_CHECK_DATA(flags)		SQUASHFS_BIT(flags, \
+						SQUASHFS_CHECK)
+
+#define SQUASHFS_MKFLAGS(noi, nod, check_data, nof, no_frag, always_frag, \
+		duplicate_checking)	(noi | (nod << 1) | (check_data << 2) \
+		| (nof << 3) | (no_frag << 4) | (always_frag << 5) | \
+		(duplicate_checking << 6))
+
+/* Max number of types and file types */
+#define SQUASHFS_DIR_TYPE		1
+#define SQUASHFS_FILE_TYPE		2
+#define SQUASHFS_SYMLINK_TYPE		3
+#define SQUASHFS_BLKDEV_TYPE		4
+#define SQUASHFS_CHRDEV_TYPE		5
+#define SQUASHFS_FIFO_TYPE		6
+#define SQUASHFS_SOCKET_TYPE		7
+#define SQUASHFS_LDIR_TYPE		8
+#define SQUASHFS_LREG_TYPE		9
+
+/* 1.0 filesystem type definitions */
+#define SQUASHFS_TYPES			5
+#define SQUASHFS_IPC_TYPE		0
+
+/* Flag whether block is compressed or uncompressed, bit is set if block is
+ * uncompressed */
+#define SQUASHFS_COMPRESSED_BIT		(1 << 15)
+
+#define SQUASHFS_COMPRESSED_SIZE(B)	(((B) & ~SQUASHFS_COMPRESSED_BIT) ? \
+		(B) & ~SQUASHFS_COMPRESSED_BIT :  SQUASHFS_COMPRESSED_BIT)
+
+#define SQUASHFS_COMPRESSED(B)		(!((B) & SQUASHFS_COMPRESSED_BIT))
+
+#define SQUASHFS_COMPRESSED_BIT_BLOCK		(1 << 24)
+
+#define SQUASHFS_COMPRESSED_SIZE_BLOCK(B)	(((B) & \
+	~SQUASHFS_COMPRESSED_BIT_BLOCK) ? (B) & \
+	~SQUASHFS_COMPRESSED_BIT_BLOCK : SQUASHFS_COMPRESSED_BIT_BLOCK)
+
+#define SQUASHFS_COMPRESSED_BLOCK(B)	(!((B) & SQUASHFS_COMPRESSED_BIT_BLOCK))
+
+/*
+ * Inode number ops.  Inodes consist of a compressed block number, and an
+ * uncompressed  offset within that block
+ */
+#define SQUASHFS_INODE_BLK(a)		((unsigned int) ((a) >> 16))
+
+#define SQUASHFS_INODE_OFFSET(a)	((unsigned int) ((a) & 0xffff))
+
+#define SQUASHFS_MKINODE(A, B)		((squashfs_inode_t)(((squashfs_inode_t) (A)\
+					<< 16) + (B)))
+
+/* Compute 32 bit VFS inode number from squashfs inode number */
+#define SQUASHFS_MK_VFS_INODE(a, b)	((unsigned int) (((a) << 8) + \
+					((b) >> 2) + 1))
+/* XXX */
+
+/* Translate between VFS mode and squashfs mode */
+#define SQUASHFS_MODE(a)		((a) & 0xfff)
+
+/* fragment and fragment table defines */
+#define SQUASHFS_FRAGMENT_BYTES(A)	(A * sizeof(struct squashfs_fragment_entry))
+
+#define SQUASHFS_FRAGMENT_INDEX(A)	(SQUASHFS_FRAGMENT_BYTES(A) / \
+					SQUASHFS_METADATA_SIZE)
+
+#define SQUASHFS_FRAGMENT_INDEX_OFFSET(A)	(SQUASHFS_FRAGMENT_BYTES(A) % \
+						SQUASHFS_METADATA_SIZE)
+
+#define SQUASHFS_FRAGMENT_INDEXES(A)	((SQUASHFS_FRAGMENT_BYTES(A) + \
+					SQUASHFS_METADATA_SIZE - 1) / \
+					SQUASHFS_METADATA_SIZE)
+
+#define SQUASHFS_FRAGMENT_INDEX_BYTES(A)	(SQUASHFS_FRAGMENT_INDEXES(A) *\
+						sizeof(long long))
+
+/* cached data constants for filesystem */
+#define SQUASHFS_CACHED_BLKS		8
+
+#define SQUASHFS_MAX_FILE_SIZE_LOG	64
+
+#define SQUASHFS_MAX_FILE_SIZE		((long long) 1 << \
+					(SQUASHFS_MAX_FILE_SIZE_LOG - 2))
+
+#define SQUASHFS_MARKER_BYTE		0xff
+
+/* meta index cache */
+#define SQUASHFS_META_INDEXES	(SQUASHFS_METADATA_SIZE / sizeof(unsigned int))
+#define SQUASHFS_META_ENTRIES	31
+#define SQUASHFS_META_NUMBER	8
+#define SQUASHFS_SLOTS		4
+
+struct meta_entry {
+	long long		data_block;
+	unsigned int		index_block;
+	unsigned short		offset;
+	unsigned short		pad;
+};
+
+struct meta_index {
+	unsigned int		inode_number;
+	unsigned int		offset;
+	unsigned short		entries;
+	unsigned short		skip;
+	unsigned short		locked;
+	unsigned short		pad;
+	struct meta_entry	meta_entry[SQUASHFS_META_ENTRIES];
+};
+
+
+/*
+ * definitions for structures on disk
+ */
+
+typedef long long		squashfs_block_t;
+typedef long long		squashfs_inode_t;
+
+struct squashfs_super_block {
+	unsigned int		s_magic;
+	unsigned int		inodes;
+	unsigned int		bytes_used_2;
+	unsigned int		uid_start_2;
+	unsigned int		guid_start_2;
+	unsigned int		inode_table_start_2;
+	unsigned int		directory_table_start_2;
+	unsigned int		s_major:16;
+	unsigned int		s_minor:16;
+	unsigned int		block_size_1:16;
+	unsigned int		block_log:16;
+	unsigned int		flags:8;
+	unsigned int		no_uids:8;
+	unsigned int		no_guids:8;
+	unsigned int		mkfs_time /* time of filesystem creation */;
+	squashfs_inode_t	root_inode;
+	unsigned int		block_size;
+	unsigned int		fragments;
+	unsigned int		fragment_table_start_2;
+	long long		bytes_used;
+	long long		uid_start;
+	long long		guid_start;
+	long long		inode_table_start;
+	long long		directory_table_start;
+	long long		fragment_table_start;
+	long long		unused;
+} __attribute__ ((packed));
+
+struct squashfs_dir_index {
+	unsigned int		index;
+	unsigned int		start_block;
+	unsigned char		size;
+	unsigned char		name[0];
+} __attribute__ ((packed));
+
+#define SQUASHFS_BASE_INODE_HEADER		\
+	unsigned int		inode_type:4;	\
+	unsigned int		mode:12;	\
+	unsigned int		uid:8;		\
+	unsigned int		guid:8;		\
+	unsigned int		mtime;		\
+	unsigned int 		inode_number;
+
+struct squashfs_base_inode_header {
+	SQUASHFS_BASE_INODE_HEADER;
+} __attribute__ ((packed));
+
+struct squashfs_ipc_inode_header {
+	SQUASHFS_BASE_INODE_HEADER;
+	unsigned int		nlink;
+} __attribute__ ((packed));
+
+struct squashfs_dev_inode_header {
+	SQUASHFS_BASE_INODE_HEADER;
+	unsigned int		nlink;
+	unsigned short		rdev;
+} __attribute__ ((packed));
+	
+struct squashfs_symlink_inode_header {
+	SQUASHFS_BASE_INODE_HEADER;
+	unsigned int		nlink;
+	unsigned short		symlink_size;
+	char			symlink[0];
+} __attribute__ ((packed));
+
+struct squashfs_reg_inode_header {
+	SQUASHFS_BASE_INODE_HEADER;
+	squashfs_block_t	start_block;
+	unsigned int		fragment;
+	unsigned int		offset;
+	unsigned int		file_size;
+	unsigned short		block_list[0];
+} __attribute__ ((packed));
+
+struct squashfs_lreg_inode_header {
+	SQUASHFS_BASE_INODE_HEADER;
+	unsigned int		nlink;
+	squashfs_block_t	start_block;
+	unsigned int		fragment;
+	unsigned int		offset;
+	long long		file_size;
+	unsigned short		block_list[0];
+} __attribute__ ((packed));
+
+struct squashfs_dir_inode_header {
+	SQUASHFS_BASE_INODE_HEADER;
+	unsigned int		nlink;
+	unsigned int		file_size:19;
+	unsigned int		offset:13;
+	unsigned int		start_block;
+	unsigned int		parent_inode;
+} __attribute__  ((packed));
+
+struct squashfs_ldir_inode_header {
+	SQUASHFS_BASE_INODE_HEADER;
+	unsigned int		nlink;
+	unsigned int		file_size:27;
+	unsigned int		offset:13;
+	unsigned int		start_block;
+	unsigned int		i_count:16;
+	unsigned int		parent_inode;
+	struct squashfs_dir_index	index[0];
+} __attribute__  ((packed));
+
+union squashfs_inode_header {
+	struct squashfs_base_inode_header	base;
+	struct squashfs_dev_inode_header	dev;
+	struct squashfs_symlink_inode_header	symlink;
+	struct squashfs_reg_inode_header	reg;
+	struct squashfs_lreg_inode_header	lreg;
+	struct squashfs_dir_inode_header	dir;
+	struct squashfs_ldir_inode_header	ldir;
+	struct squashfs_ipc_inode_header	ipc;
+};
+	
+struct squashfs_dir_entry {
+	unsigned int		offset:13;
+	unsigned int		type:3;
+	unsigned int		size:8;
+	int			inode_number:16;
+	char			name[0];
+} __attribute__ ((packed));
+
+struct squashfs_dir_header {
+	unsigned int		count:8;
+	unsigned int		start_block;
+	unsigned int		inode_number;
+} __attribute__ ((packed));
+
+struct squashfs_fragment_entry {
+	long long		start_block;
+	unsigned int		size;
+	unsigned int		unused;
+} __attribute__ ((packed));
+
+extern int squashfs_uncompress_block(void *d, int dstlen, void *s, int srclen);
+extern int squashfs_uncompress_init(void);
+extern int squashfs_uncompress_exit(void);
+
+/*
+ * macros to convert each packed bitfield structure from little endian to big
+ * endian and vice versa.  These are needed when creating or using a filesystem
+ * on a machine with different byte ordering to the target architecture.
+ *
+ */
+
+#define SQUASHFS_SWAP_START \
+	int bits;\
+	int b_pos;\
+	unsigned long long val;\
+	unsigned char *s;\
+	unsigned char *d;
+
+#define SQUASHFS_SWAP_SUPER_BLOCK(s, d) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_MEMSET(s, d, sizeof(struct squashfs_super_block));\
+	SQUASHFS_SWAP((s)->s_magic, d, 0, 32);\
+	SQUASHFS_SWAP((s)->inodes, d, 32, 32);\
+	SQUASHFS_SWAP((s)->bytes_used_2, d, 64, 32);\
+	SQUASHFS_SWAP((s)->uid_start_2, d, 96, 32);\
+	SQUASHFS_SWAP((s)->guid_start_2, d, 128, 32);\
+	SQUASHFS_SWAP((s)->inode_table_start_2, d, 160, 32);\
+	SQUASHFS_SWAP((s)->directory_table_start_2, d, 192, 32);\
+	SQUASHFS_SWAP((s)->s_major, d, 224, 16);\
+	SQUASHFS_SWAP((s)->s_minor, d, 240, 16);\
+	SQUASHFS_SWAP((s)->block_size_1, d, 256, 16);\
+	SQUASHFS_SWAP((s)->block_log, d, 272, 16);\
+	SQUASHFS_SWAP((s)->flags, d, 288, 8);\
+	SQUASHFS_SWAP((s)->no_uids, d, 296, 8);\
+	SQUASHFS_SWAP((s)->no_guids, d, 304, 8);\
+	SQUASHFS_SWAP((s)->mkfs_time, d, 312, 32);\
+	SQUASHFS_SWAP((s)->root_inode, d, 344, 64);\
+	SQUASHFS_SWAP((s)->block_size, d, 408, 32);\
+	SQUASHFS_SWAP((s)->fragments, d, 440, 32);\
+	SQUASHFS_SWAP((s)->fragment_table_start_2, d, 472, 32);\
+	SQUASHFS_SWAP((s)->bytes_used, d, 504, 64);\
+	SQUASHFS_SWAP((s)->uid_start, d, 568, 64);\
+	SQUASHFS_SWAP((s)->guid_start, d, 632, 64);\
+	SQUASHFS_SWAP((s)->inode_table_start, d, 696, 64);\
+	SQUASHFS_SWAP((s)->directory_table_start, d, 760, 64);\
+	SQUASHFS_SWAP((s)->fragment_table_start, d, 824, 64);\
+	SQUASHFS_SWAP((s)->unused, d, 888, 64);\
+}
+
+#define SQUASHFS_SWAP_BASE_INODE_CORE(s, d, n)\
+	SQUASHFS_MEMSET(s, d, n);\
+	SQUASHFS_SWAP((s)->inode_type, d, 0, 4);\
+	SQUASHFS_SWAP((s)->mode, d, 4, 12);\
+	SQUASHFS_SWAP((s)->uid, d, 16, 8);\
+	SQUASHFS_SWAP((s)->guid, d, 24, 8);\
+	SQUASHFS_SWAP((s)->mtime, d, 32, 32);\
+	SQUASHFS_SWAP((s)->inode_number, d, 64, 32);
+
+#define SQUASHFS_SWAP_BASE_INODE_HEADER(s, d, n) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_SWAP_BASE_INODE_CORE(s, d, n)\
+}
+
+#define SQUASHFS_SWAP_IPC_INODE_HEADER(s, d) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_SWAP_BASE_INODE_CORE(s, d, \
+			sizeof(struct squashfs_ipc_inode_header))\
+	SQUASHFS_SWAP((s)->nlink, d, 96, 32);\
+}
+
+#define SQUASHFS_SWAP_DEV_INODE_HEADER(s, d) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_SWAP_BASE_INODE_CORE(s, d, \
+			sizeof(struct squashfs_dev_inode_header)); \
+	SQUASHFS_SWAP((s)->nlink, d, 96, 32);\
+	SQUASHFS_SWAP((s)->rdev, d, 128, 16);\
+}
+
+#define SQUASHFS_SWAP_SYMLINK_INODE_HEADER(s, d) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_SWAP_BASE_INODE_CORE(s, d, \
+			sizeof(struct squashfs_symlink_inode_header));\
+	SQUASHFS_SWAP((s)->nlink, d, 96, 32);\
+	SQUASHFS_SWAP((s)->symlink_size, d, 128, 16);\
+}
+
+#define SQUASHFS_SWAP_REG_INODE_HEADER(s, d) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_SWAP_BASE_INODE_CORE(s, d, \
+			sizeof(struct squashfs_reg_inode_header));\
+	SQUASHFS_SWAP((s)->start_block, d, 96, 64);\
+	SQUASHFS_SWAP((s)->fragment, d, 160, 32);\
+	SQUASHFS_SWAP((s)->offset, d, 192, 32);\
+	SQUASHFS_SWAP((s)->file_size, d, 224, 32);\
+}
+
+#define SQUASHFS_SWAP_LREG_INODE_HEADER(s, d) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_SWAP_BASE_INODE_CORE(s, d, \
+			sizeof(struct squashfs_lreg_inode_header));\
+	SQUASHFS_SWAP((s)->nlink, d, 96, 32);\
+	SQUASHFS_SWAP((s)->start_block, d, 128, 64);\
+	SQUASHFS_SWAP((s)->fragment, d, 192, 32);\
+	SQUASHFS_SWAP((s)->offset, d, 224, 32);\
+	SQUASHFS_SWAP((s)->file_size, d, 256, 64);\
+}
+
+#define SQUASHFS_SWAP_DIR_INODE_HEADER(s, d) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_SWAP_BASE_INODE_CORE(s, d, \
+			sizeof(struct squashfs_dir_inode_header));\
+	SQUASHFS_SWAP((s)->nlink, d, 96, 32);\
+	SQUASHFS_SWAP((s)->file_size, d, 128, 19);\
+	SQUASHFS_SWAP((s)->offset, d, 147, 13);\
+	SQUASHFS_SWAP((s)->start_block, d, 160, 32);\
+	SQUASHFS_SWAP((s)->parent_inode, d, 192, 32);\
+}
+
+#define SQUASHFS_SWAP_LDIR_INODE_HEADER(s, d) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_SWAP_BASE_INODE_CORE(s, d, \
+			sizeof(struct squashfs_ldir_inode_header));\
+	SQUASHFS_SWAP((s)->nlink, d, 96, 32);\
+	SQUASHFS_SWAP((s)->file_size, d, 128, 27);\
+	SQUASHFS_SWAP((s)->offset, d, 155, 13);\
+	SQUASHFS_SWAP((s)->start_block, d, 168, 32);\
+	SQUASHFS_SWAP((s)->i_count, d, 200, 16);\
+	SQUASHFS_SWAP((s)->parent_inode, d, 216, 32);\
+}
+
+#define SQUASHFS_SWAP_DIR_INDEX(s, d) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_MEMSET(s, d, sizeof(struct squashfs_dir_index));\
+	SQUASHFS_SWAP((s)->index, d, 0, 32);\
+	SQUASHFS_SWAP((s)->start_block, d, 32, 32);\
+	SQUASHFS_SWAP((s)->size, d, 64, 8);\
+}
+
+#define SQUASHFS_SWAP_DIR_HEADER(s, d) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_MEMSET(s, d, sizeof(struct squashfs_dir_header));\
+	SQUASHFS_SWAP((s)->count, d, 0, 8);\
+	SQUASHFS_SWAP((s)->start_block, d, 8, 32);\
+	SQUASHFS_SWAP((s)->inode_number, d, 40, 32);\
+}
+
+#define SQUASHFS_SWAP_DIR_ENTRY(s, d) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_MEMSET(s, d, sizeof(struct squashfs_dir_entry));\
+	SQUASHFS_SWAP((s)->offset, d, 0, 13);\
+	SQUASHFS_SWAP((s)->type, d, 13, 3);\
+	SQUASHFS_SWAP((s)->size, d, 16, 8);\
+	SQUASHFS_SWAP((s)->inode_number, d, 24, 16);\
+}
+
+#define SQUASHFS_SWAP_FRAGMENT_ENTRY(s, d) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_MEMSET(s, d, sizeof(struct squashfs_fragment_entry));\
+	SQUASHFS_SWAP((s)->start_block, d, 0, 64);\
+	SQUASHFS_SWAP((s)->size, d, 64, 32);\
+}
+
+#define SQUASHFS_SWAP_SHORTS(s, d, n) {\
+	int entry;\
+	int bit_position;\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_MEMSET(s, d, n * 2);\
+	for(entry = 0, bit_position = 0; entry < n; entry++, bit_position += \
+			16)\
+		SQUASHFS_SWAP(s[entry], d, bit_position, 16);\
+}
+
+#define SQUASHFS_SWAP_INTS(s, d, n) {\
+	int entry;\
+	int bit_position;\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_MEMSET(s, d, n * 4);\
+	for(entry = 0, bit_position = 0; entry < n; entry++, bit_position += \
+			32)\
+		SQUASHFS_SWAP(s[entry], d, bit_position, 32);\
+}
+
+#define SQUASHFS_SWAP_LONG_LONGS(s, d, n) {\
+	int entry;\
+	int bit_position;\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_MEMSET(s, d, n * 8);\
+	for(entry = 0, bit_position = 0; entry < n; entry++, bit_position += \
+			64)\
+		SQUASHFS_SWAP(s[entry], d, bit_position, 64);\
+}
+
+#define SQUASHFS_SWAP_DATA(s, d, n, bits) {\
+	int entry;\
+	int bit_position;\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_MEMSET(s, d, n * bits / 8);\
+	for(entry = 0, bit_position = 0; entry < n; entry++, bit_position += \
+			bits)\
+		SQUASHFS_SWAP(s[entry], d, bit_position, bits);\
+}
+
+#define SQUASHFS_SWAP_FRAGMENT_INDEXES(s, d, n) SQUASHFS_SWAP_LONG_LONGS(s, d, n)
+
+#ifdef CONFIG_SQUASHFS_1_0_COMPATIBILITY
+
+struct squashfs_base_inode_header_1 {
+	unsigned int		inode_type:4;
+	unsigned int		mode:12; /* protection */
+	unsigned int		uid:4; /* index into uid table */
+	unsigned int		guid:4; /* index into guid table */
+} __attribute__ ((packed));
+
+struct squashfs_ipc_inode_header_1 {
+	unsigned int		inode_type:4;
+	unsigned int		mode:12; /* protection */
+	unsigned int		uid:4; /* index into uid table */
+	unsigned int		guid:4; /* index into guid table */
+	unsigned int		type:4;
+	unsigned int		offset:4;
+} __attribute__ ((packed));
+
+struct squashfs_dev_inode_header_1 {
+	unsigned int		inode_type:4;
+	unsigned int		mode:12; /* protection */
+	unsigned int		uid:4; /* index into uid table */
+	unsigned int		guid:4; /* index into guid table */
+	unsigned short		rdev;
+} __attribute__ ((packed));
+	
+struct squashfs_symlink_inode_header_1 {
+	unsigned int		inode_type:4;
+	unsigned int		mode:12; /* protection */
+	unsigned int		uid:4; /* index into uid table */
+	unsigned int		guid:4; /* index into guid table */
+	unsigned short		symlink_size;
+	char			symlink[0];
+} __attribute__ ((packed));
+
+struct squashfs_reg_inode_header_1 {
+	unsigned int		inode_type:4;
+	unsigned int		mode:12; /* protection */
+	unsigned int		uid:4; /* index into uid table */
+	unsigned int		guid:4; /* index into guid table */
+	unsigned int		mtime;
+	unsigned int		start_block;
+	unsigned int		file_size:32;
+	unsigned short		block_list[0];
+} __attribute__ ((packed));
+
+struct squashfs_dir_inode_header_1 {
+	unsigned int		inode_type:4;
+	unsigned int		mode:12; /* protection */
+	unsigned int		uid:4; /* index into uid table */
+	unsigned int		guid:4; /* index into guid table */
+	unsigned int		file_size:19;
+	unsigned int		offset:13;
+	unsigned int		mtime;
+	unsigned int		start_block:24;
+} __attribute__  ((packed));
+
+#define SQUASHFS_SWAP_BASE_INODE_CORE_1(s, d, n) \
+	SQUASHFS_MEMSET(s, d, n);\
+	SQUASHFS_SWAP((s)->inode_type, d, 0, 4);\
+	SQUASHFS_SWAP((s)->mode, d, 4, 12);\
+	SQUASHFS_SWAP((s)->uid, d, 16, 4);\
+	SQUASHFS_SWAP((s)->guid, d, 20, 4);
+
+#define SQUASHFS_SWAP_BASE_INODE_HEADER_1(s, d, n) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_SWAP_BASE_INODE_CORE_1(s, d, n)\
+}
+
+#define SQUASHFS_SWAP_IPC_INODE_HEADER_1(s, d) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_SWAP_BASE_INODE_CORE_1(s, d, \
+			sizeof(struct squashfs_ipc_inode_header_1));\
+	SQUASHFS_SWAP((s)->type, d, 24, 4);\
+	SQUASHFS_SWAP((s)->offset, d, 28, 4);\
+}
+
+#define SQUASHFS_SWAP_DEV_INODE_HEADER_1(s, d) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_SWAP_BASE_INODE_CORE_1(s, d, \
+			sizeof(struct squashfs_dev_inode_header_1));\
+	SQUASHFS_SWAP((s)->rdev, d, 24, 16);\
+}
+
+#define SQUASHFS_SWAP_SYMLINK_INODE_HEADER_1(s, d) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_SWAP_BASE_INODE_CORE_1(s, d, \
+			sizeof(struct squashfs_symlink_inode_header_1));\
+	SQUASHFS_SWAP((s)->symlink_size, d, 24, 16);\
+}
+
+#define SQUASHFS_SWAP_REG_INODE_HEADER_1(s, d) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_SWAP_BASE_INODE_CORE_1(s, d, \
+			sizeof(struct squashfs_reg_inode_header_1));\
+	SQUASHFS_SWAP((s)->mtime, d, 24, 32);\
+	SQUASHFS_SWAP((s)->start_block, d, 56, 32);\
+	SQUASHFS_SWAP((s)->file_size, d, 88, 32);\
+}
+
+#define SQUASHFS_SWAP_DIR_INODE_HEADER_1(s, d) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_SWAP_BASE_INODE_CORE_1(s, d, \
+			sizeof(struct squashfs_dir_inode_header_1));\
+	SQUASHFS_SWAP((s)->file_size, d, 24, 19);\
+	SQUASHFS_SWAP((s)->offset, d, 43, 13);\
+	SQUASHFS_SWAP((s)->mtime, d, 56, 32);\
+	SQUASHFS_SWAP((s)->start_block, d, 88, 24);\
+}
+
+#endif
+
+#ifdef CONFIG_SQUASHFS_2_0_COMPATIBILITY
+
+struct squashfs_dir_index_2 {
+	unsigned int		index:27;
+	unsigned int		start_block:29;
+	unsigned char		size;
+	unsigned char		name[0];
+} __attribute__ ((packed));
+
+struct squashfs_base_inode_header_2 {
+	unsigned int		inode_type:4;
+	unsigned int		mode:12; /* protection */
+	unsigned int		uid:8; /* index into uid table */
+	unsigned int		guid:8; /* index into guid table */
+} __attribute__ ((packed));
+
+struct squashfs_ipc_inode_header_2 {
+	unsigned int		inode_type:4;
+	unsigned int		mode:12; /* protection */
+	unsigned int		uid:8; /* index into uid table */
+	unsigned int		guid:8; /* index into guid table */
+} __attribute__ ((packed));
+
+struct squashfs_dev_inode_header_2 {
+	unsigned int		inode_type:4;
+	unsigned int		mode:12; /* protection */
+	unsigned int		uid:8; /* index into uid table */
+	unsigned int		guid:8; /* index into guid table */
+	unsigned short		rdev;
+} __attribute__ ((packed));
+	
+struct squashfs_symlink_inode_header_2 {
+	unsigned int		inode_type:4;
+	unsigned int		mode:12; /* protection */
+	unsigned int		uid:8; /* index into uid table */
+	unsigned int		guid:8; /* index into guid table */
+	unsigned short		symlink_size;
+	char			symlink[0];
+} __attribute__ ((packed));
+
+struct squashfs_reg_inode_header_2 {
+	unsigned int		inode_type:4;
+	unsigned int		mode:12; /* protection */
+	unsigned int		uid:8; /* index into uid table */
+	unsigned int		guid:8; /* index into guid table */
+	unsigned int		mtime;
+	unsigned int		start_block;
+	unsigned int		fragment;
+	unsigned int		offset;
+	unsigned int		file_size:32;
+	unsigned short		block_list[0];
+} __attribute__ ((packed));
+
+struct squashfs_dir_inode_header_2 {
+	unsigned int		inode_type:4;
+	unsigned int		mode:12; /* protection */
+	unsigned int		uid:8; /* index into uid table */
+	unsigned int		guid:8; /* index into guid table */
+	unsigned int		file_size:19;
+	unsigned int		offset:13;
+	unsigned int		mtime;
+	unsigned int		start_block:24;
+} __attribute__  ((packed));
+
+struct squashfs_ldir_inode_header_2 {
+	unsigned int		inode_type:4;
+	unsigned int		mode:12; /* protection */
+	unsigned int		uid:8; /* index into uid table */
+	unsigned int		guid:8; /* index into guid table */
+	unsigned int		file_size:27;
+	unsigned int		offset:13;
+	unsigned int		mtime;
+	unsigned int		start_block:24;
+	unsigned int		i_count:16;
+	struct squashfs_dir_index_2	index[0];
+} __attribute__  ((packed));
+
+union squashfs_inode_header_2 {
+	struct squashfs_base_inode_header_2	base;
+	struct squashfs_dev_inode_header_2	dev;
+	struct squashfs_symlink_inode_header_2	symlink;
+	struct squashfs_reg_inode_header_2	reg;
+	struct squashfs_dir_inode_header_2	dir;
+	struct squashfs_ldir_inode_header_2	ldir;
+	struct squashfs_ipc_inode_header_2	ipc;
+};
+	
+struct squashfs_dir_header_2 {
+	unsigned int		count:8;
+	unsigned int		start_block:24;
+} __attribute__ ((packed));
+
+struct squashfs_dir_entry_2 {
+	unsigned int		offset:13;
+	unsigned int		type:3;
+	unsigned int		size:8;
+	char			name[0];
+} __attribute__ ((packed));
+
+struct squashfs_fragment_entry_2 {
+	unsigned int		start_block;
+	unsigned int		size;
+} __attribute__ ((packed));
+
+#define SQUASHFS_SWAP_BASE_INODE_CORE_2(s, d, n)\
+	SQUASHFS_MEMSET(s, d, n);\
+	SQUASHFS_SWAP((s)->inode_type, d, 0, 4);\
+	SQUASHFS_SWAP((s)->mode, d, 4, 12);\
+	SQUASHFS_SWAP((s)->uid, d, 16, 8);\
+	SQUASHFS_SWAP((s)->guid, d, 24, 8);\
+
+#define SQUASHFS_SWAP_BASE_INODE_HEADER_2(s, d, n) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_SWAP_BASE_INODE_CORE_2(s, d, n)\
+}
+
+#define SQUASHFS_SWAP_IPC_INODE_HEADER_2(s, d) \
+	SQUASHFS_SWAP_BASE_INODE_HEADER_2(s, d, sizeof(struct squashfs_ipc_inode_header_2))
+
+#define SQUASHFS_SWAP_DEV_INODE_HEADER_2(s, d) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_SWAP_BASE_INODE_CORE_2(s, d, \
+			sizeof(struct squashfs_dev_inode_header_2)); \
+	SQUASHFS_SWAP((s)->rdev, d, 32, 16);\
+}
+
+#define SQUASHFS_SWAP_SYMLINK_INODE_HEADER_2(s, d) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_SWAP_BASE_INODE_CORE_2(s, d, \
+			sizeof(struct squashfs_symlink_inode_header_2));\
+	SQUASHFS_SWAP((s)->symlink_size, d, 32, 16);\
+}
+
+#define SQUASHFS_SWAP_REG_INODE_HEADER_2(s, d) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_SWAP_BASE_INODE_CORE_2(s, d, \
+			sizeof(struct squashfs_reg_inode_header_2));\
+	SQUASHFS_SWAP((s)->mtime, d, 32, 32);\
+	SQUASHFS_SWAP((s)->start_block, d, 64, 32);\
+	SQUASHFS_SWAP((s)->fragment, d, 96, 32);\
+	SQUASHFS_SWAP((s)->offset, d, 128, 32);\
+	SQUASHFS_SWAP((s)->file_size, d, 160, 32);\
+}
+
+#define SQUASHFS_SWAP_DIR_INODE_HEADER_2(s, d) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_SWAP_BASE_INODE_CORE_2(s, d, \
+			sizeof(struct squashfs_dir_inode_header_2));\
+	SQUASHFS_SWAP((s)->file_size, d, 32, 19);\
+	SQUASHFS_SWAP((s)->offset, d, 51, 13);\
+	SQUASHFS_SWAP((s)->mtime, d, 64, 32);\
+	SQUASHFS_SWAP((s)->start_block, d, 96, 24);\
+}
+
+#define SQUASHFS_SWAP_LDIR_INODE_HEADER_2(s, d) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_SWAP_BASE_INODE_CORE_2(s, d, \
+			sizeof(struct squashfs_ldir_inode_header_2));\
+	SQUASHFS_SWAP((s)->file_size, d, 32, 27);\
+	SQUASHFS_SWAP((s)->offset, d, 59, 13);\
+	SQUASHFS_SWAP((s)->mtime, d, 72, 32);\
+	SQUASHFS_SWAP((s)->start_block, d, 104, 24);\
+	SQUASHFS_SWAP((s)->i_count, d, 128, 16);\
+}
+
+#define SQUASHFS_SWAP_DIR_INDEX_2(s, d) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_MEMSET(s, d, sizeof(struct squashfs_dir_index_2));\
+	SQUASHFS_SWAP((s)->index, d, 0, 27);\
+	SQUASHFS_SWAP((s)->start_block, d, 27, 29);\
+	SQUASHFS_SWAP((s)->size, d, 56, 8);\
+}
+#define SQUASHFS_SWAP_DIR_HEADER_2(s, d) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_MEMSET(s, d, sizeof(struct squashfs_dir_header_2));\
+	SQUASHFS_SWAP((s)->count, d, 0, 8);\
+	SQUASHFS_SWAP((s)->start_block, d, 8, 24);\
+}
+
+#define SQUASHFS_SWAP_DIR_ENTRY_2(s, d) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_MEMSET(s, d, sizeof(struct squashfs_dir_entry_2));\
+	SQUASHFS_SWAP((s)->offset, d, 0, 13);\
+	SQUASHFS_SWAP((s)->type, d, 13, 3);\
+	SQUASHFS_SWAP((s)->size, d, 16, 8);\
+}
+
+#define SQUASHFS_SWAP_FRAGMENT_ENTRY_2(s, d) {\
+	SQUASHFS_SWAP_START\
+	SQUASHFS_MEMSET(s, d, sizeof(struct squashfs_fragment_entry_2));\
+	SQUASHFS_SWAP((s)->start_block, d, 0, 32);\
+	SQUASHFS_SWAP((s)->size, d, 32, 32);\
+}
+
+#define SQUASHFS_SWAP_FRAGMENT_INDEXES_2(s, d, n) SQUASHFS_SWAP_INTS(s, d, n)
+
+/* fragment and fragment table defines */
+#define SQUASHFS_FRAGMENT_BYTES_2(A)	(A * sizeof(struct squashfs_fragment_entry_2))
+
+#define SQUASHFS_FRAGMENT_INDEX_2(A)	(SQUASHFS_FRAGMENT_BYTES_2(A) / \
+					SQUASHFS_METADATA_SIZE)
+
+#define SQUASHFS_FRAGMENT_INDEX_OFFSET_2(A)	(SQUASHFS_FRAGMENT_BYTES_2(A) % \
+						SQUASHFS_METADATA_SIZE)
+
+#define SQUASHFS_FRAGMENT_INDEXES_2(A)	((SQUASHFS_FRAGMENT_BYTES_2(A) + \
+					SQUASHFS_METADATA_SIZE - 1) / \
+					SQUASHFS_METADATA_SIZE)
+
+#define SQUASHFS_FRAGMENT_INDEX_BYTES_2(A)	(SQUASHFS_FRAGMENT_INDEXES_2(A) *\
+						sizeof(int))
+
+#endif
+
+#ifdef __KERNEL__
+
+/*
+ * macros used to swap each structure entry, taking into account
+ * bitfields and different bitfield placing conventions on differing
+ * architectures
+ */
+
+#include <asm/byteorder.h>
+
+#ifdef __BIG_ENDIAN
+	/* convert from little endian to big endian */
+#define SQUASHFS_SWAP(value, p, pos, tbits) _SQUASHFS_SWAP(value, p, pos, \
+		tbits, b_pos)
+#else
+	/* convert from big endian to little endian */ 
+#define SQUASHFS_SWAP(value, p, pos, tbits) _SQUASHFS_SWAP(value, p, pos, \
+		tbits, 64 - tbits - b_pos)
+#endif
+
+#define _SQUASHFS_SWAP(value, p, pos, tbits, SHIFT) {\
+	b_pos = pos % 8;\
+	val = 0;\
+	s = (unsigned char *)p + (pos / 8);\
+	d = ((unsigned char *) &val) + 7;\
+	for(bits = 0; bits < (tbits + b_pos); bits += 8) \
+		*d-- = *s++;\
+	value = (val >> (SHIFT))/* & ((1 << tbits) - 1)*/;\
+}
+
+#define SQUASHFS_MEMSET(s, d, n)	memset(s, 0, n);
+
+#endif
+#endif

SQUASHFS/squashfs-tools-4.4/kernel/kernel-2.4/include/linux/squashfs_fs_i.h

+#ifndef SQUASHFS_FS_I
+#define SQUASHFS_FS_I
+/*
+ * Squashfs
+ *
+ * Copyright (c) 2002, 2003, 2004, 2005, 2006
+ * Phillip Lougher <phillip@lougher.demon.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2,
+ * or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * squashfs_fs_i.h
+ */
+
+struct squashfs_inode_info {
+	long long	start_block;
+	unsigned int	offset;
+	union {
+		struct {
+			long long	fragment_start_block;
+			unsigned int	fragment_size;
+			unsigned int	fragment_offset;
+			long long	block_list_start;
+		} s1;
+		struct {
+			long long	directory_index_start;
+			unsigned int	directory_index_offset;
+			unsigned int	directory_index_count;
+			unsigned int	parent_inode;
+		} s2;
+	} u;
+};
+#endif

SQUASHFS/squashfs-tools-4.4/kernel/kernel-2.4/include/linux/squashfs_fs_sb.h

+#ifndef SQUASHFS_FS_SB
+#define SQUASHFS_FS_SB
+/*
+ * Squashfs
+ *
+ * Copyright (c) 2002, 2003, 2004, 2005, 2006
+ * Phillip Lougher <phillip@lougher.demon.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2,
+ * or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * squashfs_fs_sb.h
+ */
+
+#include <linux/squashfs_fs.h>
+#include <linux/zlib.h>
+
+struct squashfs_cache {
+	long long	block;
+	int		length;
+	long long	next_index;
+	char		*data;
+};
+
+struct squashfs_fragment_cache {
+	long long	block;
+	int		length;
+	unsigned int	locked;
+	char		*data;
+};
+
+struct squashfs_sb_info {
+	struct squashfs_super_block	sblk;
+	int			devblksize;
+	int			devblksize_log2;
+	int			swap;
+	struct squashfs_cache	*block_cache;
+	struct squashfs_fragment_cache	*fragment;
+	int			next_cache;
+	int			next_fragment;
+	int			next_meta_index;
+	unsigned int		*uid;
+	unsigned int		*guid;
+	long long		*fragment_index;
+	unsigned int		*fragment_index_2;
+	unsigned int		read_size;
+	char			*read_data;
+	char			*read_page;
+	struct semaphore	read_data_mutex;
+	struct semaphore	read_page_mutex;
+	struct semaphore	block_cache_mutex;
+	struct semaphore	fragment_mutex;
+	struct semaphore	meta_index_mutex;
+	wait_queue_head_t	waitq;
+	wait_queue_head_t	fragment_wait_queue;
+	struct meta_index	*meta_index;
+	z_stream		stream;
+	struct inode		*(*iget)(struct super_block *s,  squashfs_inode_t
+				inode);
+	long long		(*read_blocklist)(struct inode *inode, int
+				index, int readahead_blks, char *block_list,
+				unsigned short **block_p, unsigned int *bsize);
+	int			(*read_fragment_index_table)(struct super_block *s);
+};
+#endif

SQUASHFS/squashfs-tools-4.4/kernel/kernel-2.6/Documentation/filesystems/squashfs.txt

+SQUASHFS 4.0 FILESYSTEM
+=======================
+
+Squashfs is a compressed read-only filesystem for Linux.
+It uses zlib compression to compress files, inodes and directories.
+Inodes in the system are very small and all blocks are packed to minimise
+data overhead. Block sizes greater than 4K are supported up to a maximum
+of 1Mbytes (default block size 128K).
+
+Squashfs is intended for general read-only filesystem use, for archival
+use (i.e. in cases where a .tar.gz file may be used), and in constrained
+block device/memory systems (e.g. embedded systems) where low overhead is
+needed.
+
+Mailing list: squashfs-devel@lists.sourceforge.net
+Web site: www.squashfs.org
+
+1. FILESYSTEM FEATURES
+----------------------
+
+Squashfs filesystem features versus Cramfs:
+
+				Squashfs		Cramfs
+
+Max filesystem size:		2^64			16 MiB
+Max file size:			~ 2 TiB			16 MiB
+Max files:			unlimited		unlimited
+Max directories:		unlimited		unlimited
+Max entries per directory:	unlimited		unlimited
+Max block size:			1 MiB			4 KiB
+Metadata compression:		yes			no
+Directory indexes:		yes			no
+Sparse file support:		yes			no
+Tail-end packing (fragments):	yes			no
+Exportable (NFS etc.):		yes			no
+Hard link support:		yes			no
+"." and ".." in readdir:	yes			no
+Real inode numbers:		yes			no
+32-bit uids/gids:		yes			no
+File creation time:		yes			no
+Xattr and ACL support:		no			no
+
+Squashfs compresses data, inodes and directories.  In addition, inode and
+directory data are highly compacted, and packed on byte boundaries.  Each
+compressed inode is on average 8 bytes in length (the exact length varies on
+file type, i.e. regular file, directory, symbolic link, and block/char device
+inodes have different sizes).
+
+2. USING SQUASHFS
+-----------------
+
+As squashfs is a read-only filesystem, the mksquashfs program must be used to
+create populated squashfs filesystems.  This and other squashfs utilities
+can be obtained from http://www.squashfs.org.  Usage instructions can be
+obtained from this site also.
+
+
+3. SQUASHFS FILESYSTEM DESIGN
+-----------------------------
+
+A squashfs filesystem consists of seven parts, packed together on a byte
+alignment:
+
+	 ---------------
+	|  superblock 	|
+	|---------------|
+	|  datablocks   |
+	|  & fragments  |
+	|---------------|
+	|  inode table	|
+	|---------------|
+	|   directory	|
+	|     table     |
+	|---------------|
+	|   fragment	|
+	|    table      |
+	|---------------|
+	|    export     |
+	|    table      |
+	|---------------|
+	|    uid/gid	|
+	|  lookup table	|
+	 ---------------
+
+Compressed data blocks are written to the filesystem as files are read from
+the source directory, and checked for duplicates.  Once all file data has been
+written the completed inode, directory, fragment, export and uid/gid lookup
+tables are written.
+
+3.1 Inodes
+----------
+
+Metadata (inodes and directories) are compressed in 8Kbyte blocks.  Each
+compressed block is prefixed by a two byte length, the top bit is set if the
+block is uncompressed.  A block will be uncompressed if the -noI option is set,
+or if the compressed block was larger than the uncompressed block.
+
+Inodes are packed into the metadata blocks, and are not aligned to block
+boundaries, therefore inodes overlap compressed blocks.  Inodes are identified
+by a 48-bit number which encodes the location of the compressed metadata block
+containing the inode, and the byte offset into that block where the inode is
+placed (<block, offset>).
+
+To maximise compression there are different inodes for each file type
+(regular file, directory, device, etc.), the inode contents and length
+varying with the type.
+
+To further maximise compression, two types of regular file inode and
+directory inode are defined: inodes optimised for frequently occurring
+regular files and directories, and extended types where extra
+information has to be stored.
+
+3.2 Directories
+---------------
+
+Like inodes, directories are packed into compressed metadata blocks, stored
+in a directory table.  Directories are accessed using the start address of
+the metablock containing the directory and the offset into the
+decompressed block (<block, offset>).
+
+Directories are organised in a slightly complex way, and are not simply
+a list of file names.  The organisation takes advantage of the
+fact that (in most cases) the inodes of the files will be in the same
+compressed metadata block, and therefore, can share the start block.
+Directories are therefore organised in a two level list, a directory
+header containing the shared start block value, and a sequence of directory
+entries, each of which share the shared start block.  A new directory header
+is written once/if the inode start block changes.  The directory
+header/directory entry list is repeated as many times as necessary.
+
+Directories are sorted, and can contain a directory index to speed up
+file lookup.  Directory indexes store one entry per metablock, each entry
+storing the index/filename mapping to the first directory header
+in each metadata block.  Directories are sorted in alphabetical order,
+and at lookup the index is scanned linearly looking for the first filename
+alphabetically larger than the filename being looked up.  At this point the
+location of the metadata block the filename is in has been found.
+The general idea of the index is ensure only one metadata block needs to be
+decompressed to do a lookup irrespective of the length of the directory.
+This scheme has the advantage that it doesn't require extra memory overhead
+and doesn't require much extra storage on disk.
+
+3.3 File data
+-------------
+
+Regular files consist of a sequence of contiguous compressed blocks, and/or a
+compressed fragment block (tail-end packed block).   The compressed size
+of each datablock is stored in a block list contained within the
+file inode.
+
+To speed up access to datablocks when reading 'large' files (256 Mbytes or
+larger), the code implements an index cache that caches the mapping from
+block index to datablock location on disk.
+
+The index cache allows Squashfs to handle large files (up to 1.75 TiB) while
+retaining a simple and space-efficient block list on disk.  The cache
+is split into slots, caching up to eight 224 GiB files (128 KiB blocks).
+Larger files use multiple slots, with 1.75 TiB files using all 8 slots.
+The index cache is designed to be memory efficient, and by default uses
+16 KiB.
+
+3.4 Fragment lookup table
+-------------------------
+
+Regular files can contain a fragment index which is mapped to a fragment
+location on disk and compressed size using a fragment lookup table.  This
+fragment lookup table is itself stored compressed into metadata blocks.
+A second index table is used to locate these.  This second index table for
+speed of access (and because it is small) is read at mount time and cached
+in memory.
+
+3.5 Uid/gid lookup table
+------------------------
+
+For space efficiency regular files store uid and gid indexes, which are
+converted to 32-bit uids/gids using an id look up table.  This table is
+stored compressed into metadata blocks.  A second index table is used to
+locate these.  This second index table for speed of access (and because it
+is small) is read at mount time and cached in memory.
+
+3.6 Export table
+----------------
+
+To enable Squashfs filesystems to be exportable (via NFS etc.) filesystems
+can optionally (disabled with the -no-exports Mksquashfs option) contain
+an inode number to inode disk location lookup table.  This is required to
+enable Squashfs to map inode numbers passed in filehandles to the inode
+location on disk, which is necessary when the export code reinstantiates
+expired/flushed inodes.
+
+This table is stored compressed into metadata blocks.  A second index table is
+used to locate these.  This second index table for speed of access (and because
+it is small) is read at mount time and cached in memory.
+
+
+4. TODOS AND OUTSTANDING ISSUES
+-------------------------------
+
+4.1 Todo list
+-------------
+
+Implement Xattr and ACL support.  The Squashfs 4.0 filesystem layout has hooks
+for these but the code has not been written.  Once the code has been written
+the existing layout should not require modification.
+
+4.2 Squashfs internal cache
+---------------------------
+
+Blocks in Squashfs are compressed.  To avoid repeatedly decompressing
+recently accessed data Squashfs uses two small metadata and fragment caches.
+
+The cache is not used for file datablocks, these are decompressed and cached in
+the page-cache in the normal way.  The cache is used to temporarily cache
+fragment and metadata blocks which have been read as a result of a metadata
+(i.e. inode or directory) or fragment access.  Because metadata and fragments
+are packed together into blocks (to gain greater compression) the read of a
+particular piece of metadata or fragment will retrieve other metadata/fragments
+which have been packed with it, these because of locality-of-reference may be
+read in the near future. Temporarily caching them ensures they are available
+for near future access without requiring an additional read and decompress.
+
+In the future this internal cache may be replaced with an implementation which
+uses the kernel page cache.  Because the page cache operates on page sized
+units this may introduce additional complexity in terms of locking and
+associated race conditions.

SQUASHFS/squashfs-tools-4.4/kernel/kernel-2.6/fs/squashfs/Makefile

+#
+# Makefile for the linux squashfs routines.
+#
+
+obj-$(CONFIG_SQUASHFS) += squashfs.o
+squashfs-y += block.o cache.o dir.o export.o file.o fragment.o id.o inode.o
+squashfs-y += namei.o super.o symlink.o
+#squashfs-y += squashfs2_0.o

SQUASHFS/squashfs-tools-4.4/kernel/kernel-2.6/fs/squashfs/block.c

+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
+ * Phillip Lougher <phillip@lougher.demon.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2,
+ * or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * block.c
+ */
+
+/*
+ * This file implements the low-level routines to read and decompress
+ * datablocks and metadata blocks.
+ */
+
+#include <linux/fs.h>
+#include <linux/vfs.h>
+#include <linux/slab.h>
+#include <linux/mutex.h>
+#include <linux/string.h>
+#include <linux/buffer_head.h>
+#include <linux/zlib.h>
+
+#include "squashfs_fs.h"
+#include "squashfs_fs_sb.h"
+#include "squashfs_fs_i.h"
+#include "squashfs.h"
+
+/*
+ * Read the metadata block length, this is stored in the first two
+ * bytes of the metadata block.
+ */
+static struct buffer_head *get_block_length(struct super_block *sb,
+			u64 *cur_index, int *offset, int *length)
+{
+	struct squashfs_sb_info *msblk = sb->s_fs_info;
+	struct buffer_head *bh;
+
+	bh = sb_bread(sb, *cur_index);
+	if (bh == NULL)
+		return NULL;
+
+	if (msblk->devblksize - *offset == 1) {
+		*length = (unsigned char) bh->b_data[*offset];
+		put_bh(bh);
+		bh = sb_bread(sb, ++(*cur_index));
+		if (bh == NULL)
+			return NULL;
+		*length |= (unsigned char) bh->b_data[0] << 8;
+		*offset = 1;
+	} else {
+		*length = (unsigned char) bh->b_data[*offset] |
+			(unsigned char) bh->b_data[*offset + 1] << 8;
+		*offset += 2;
+	}
+
+	return bh;
+}
+
+
+/*
+ * Read and decompress a metadata block or datablock.  Length is non-zero
+ * if a datablock is being read (the size is stored elsewhere in the
+ * filesystem), otherwise the length is obtained from the first two bytes of
+ * the metadata block.  A bit in the length field indicates if the block
+ * is stored uncompressed in the filesystem (usually because compression
+ * generated a larger block - this does occasionally happen with zlib).
+ */
+int squashfs_read_data(struct super_block *sb, void **buffer, u64 index,
+			int length, u64 *next_index, int srclength)
+{
+	struct squashfs_sb_info *msblk = sb->s_fs_info;
+	struct buffer_head **bh;
+	int offset = index & ((1 << msblk->devblksize_log2) - 1);
+	u64 cur_index = index >> msblk->devblksize_log2;
+	int bytes, compressed, b = 0, k = 0, page = 0, avail;
+
+
+	bh = kcalloc((msblk->block_size >> msblk->devblksize_log2) + 1,
+				sizeof(*bh), GFP_KERNEL);
+	if (bh == NULL)
+		return -ENOMEM;
+
+	if (length) {
+		/*
+		 * Datablock.
+		 */
+		bytes = -offset;
+		compressed = SQUASHFS_COMPRESSED_BLOCK(length);
+		length = SQUASHFS_COMPRESSED_SIZE_BLOCK(length);
+		if (next_index)
+			*next_index = index + length;
+
+		TRACE("Block @ 0x%llx, %scompressed size %d, src size %d\n",
+			index, compressed ? "" : "un", length, srclength);
+
+		if (length < 0 || length > srclength ||
+				(index + length) > msblk->bytes_used)
+			goto read_failure;
+
+		for (b = 0; bytes < length; b++, cur_index++) {
+			bh[b] = sb_getblk(sb, cur_index);
+			if (bh[b] == NULL)
+				goto block_release;
+			bytes += msblk->devblksize;
+		}
+		ll_rw_block(READ, b, bh);
+	} else {
+		/*
+		 * Metadata block.
+		 */
+		if ((index + 2) > msblk->bytes_used)
+			goto read_failure;
+
+		bh[0] = get_block_length(sb, &cur_index, &offset, &length);
+		if (bh[0] == NULL)
+			goto read_failure;
+		b = 1;
+
+		bytes = msblk->devblksize - offset;
+		compressed = SQUASHFS_COMPRESSED(length);
+		length = SQUASHFS_COMPRESSED_SIZE(length);
+		if (next_index)
+			*next_index = index + length + 2;
+
+		TRACE("Block @ 0x%llx, %scompressed size %d\n", index,
+				compressed ? "" : "un", length);
+
+		if (length < 0 || length > srclength ||
+					(index + length) > msblk->bytes_used)
+			goto block_release;
+
+		for (; bytes < length; b++) {
+			bh[b] = sb_getblk(sb, ++cur_index);
+			if (bh[b] == NULL)
+				goto block_release;
+			bytes += msblk->devblksize;
+		}
+		ll_rw_block(READ, b - 1, bh + 1);
+	}
+
+	if (compressed) {
+		int zlib_err = 0, zlib_init = 0;
+
+		/*
+		 * Uncompress block.
+		 */
+
+		mutex_lock(&msblk->read_data_mutex);
+
+		msblk->stream.avail_out = 0;
+		msblk->stream.avail_in = 0;
+
+		bytes = length;
+		do {
+			if (msblk->stream.avail_in == 0 && k < b) {
+				avail = min(bytes, msblk->devblksize - offset);
+				bytes -= avail;
+				wait_on_buffer(bh[k]);
+				if (!buffer_uptodate(bh[k]))
+					goto release_mutex;
+
+				if (avail == 0) {
+					offset = 0;
+					put_bh(bh[k++]);
+					continue;
+				}
+
+				msblk->stream.next_in = bh[k]->b_data + offset;
+				msblk->stream.avail_in = avail;
+				offset = 0;
+			}
+
+			if (msblk->stream.avail_out == 0) {
+				msblk->stream.next_out = buffer[page++];
+				msblk->stream.avail_out = PAGE_CACHE_SIZE;
+			}
+
+			if (!zlib_init) {
+				zlib_err = zlib_inflateInit(&msblk->stream);
+				if (zlib_err != Z_OK) {
+					ERROR("zlib_inflateInit returned"
+						" unexpected result 0x%x,"
+						" srclength %d\n", zlib_err,
+						srclength);
+					goto release_mutex;
+				}
+				zlib_init = 1;
+			}
+
+			zlib_err = zlib_inflate(&msblk->stream, Z_NO_FLUSH);
+
+			if (msblk->stream.avail_in == 0 && k < b)
+				put_bh(bh[k++]);
+		} while (zlib_err == Z_OK);
+
+		if (zlib_err != Z_STREAM_END) {
+			ERROR("zlib_inflate returned unexpected result"
+				" 0x%x, srclength %d, avail_in %d,"
+				" avail_out %d\n", zlib_err, srclength,
+				msblk->stream.avail_in,
+				msblk->stream.avail_out);
+			goto release_mutex;
+		}
+
+		zlib_err = zlib_inflateEnd(&msblk->stream);
+		if (zlib_err != Z_OK) {
+			ERROR("zlib_inflateEnd returned unexpected result 0x%x,"
+				" srclength %d\n", zlib_err, srclength);
+			goto release_mutex;
+		}
+		length = msblk->stream.total_out;
+		mutex_unlock(&msblk->read_data_mutex);
+	} else {
+		/*
+		 * Block is uncompressed.
+		 */
+		int i, in, pg_offset = 0;
+
+		for (i = 0; i < b; i++) {
+			wait_on_buffer(bh[i]);
+			if (!buffer_uptodate(bh[i]))
+				goto block_release;
+		}
+
+		for (bytes = length; k < b; k++) {
+			in = min(bytes, msblk->devblksize - offset);
+			bytes -= in;
+			while (in) {
+				if (pg_offset == PAGE_CACHE_SIZE) {
+					page++;
+					pg_offset = 0;
+				}
+				avail = min_t(int, in, PAGE_CACHE_SIZE -
+						pg_offset);
+				memcpy(buffer[page] + pg_offset,
+						bh[k]->b_data + offset, avail);
+				in -= avail;
+				pg_offset += avail;
+				offset += avail;
+			}
+			offset = 0;
+			put_bh(bh[k]);
+		}
+	}
+
+	kfree(bh);
+	return length;
+
+release_mutex:
+	mutex_unlock(&msblk->read_data_mutex);
+
+block_release:
+	for (; k < b; k++)
+		put_bh(bh[k]);
+
+read_failure:
+	ERROR("sb_bread failed reading block 0x%llx\n", cur_index);
+	kfree(bh);
+	return -EIO;
+}

SQUASHFS/squashfs-tools-4.4/kernel/kernel-2.6/fs/squashfs/cache.c

+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
+ * Phillip Lougher <phillip@lougher.demon.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2,
+ * or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * cache.c
+ */
+
+/*
+ * Blocks in Squashfs are compressed.  To avoid repeatedly decompressing
+ * recently accessed data Squashfs uses two small metadata and fragment caches.
+ *
+ * This file implements a generic cache implementation used for both caches,
+ * plus functions layered ontop of the generic cache implementation to
+ * access the metadata and fragment caches.
+ *
+ * To avoid out of memory and fragmentation isssues with vmalloc the cache
+ * uses sequences of kmalloced PAGE_CACHE_SIZE buffers.
+ *
+ * It should be noted that the cache is not used for file datablocks, these
+ * are decompressed and cached in the page-cache in the normal way.  The
+ * cache is only used to temporarily cache fragment and metadata blocks
+ * which have been read as as a result of a metadata (i.e. inode or
+ * directory) or fragment access.  Because metadata and fragments are packed
+ * together into blocks (to gain greater compression) the read of a particular
+ * piece of metadata or fragment will retrieve other metadata/fragments which
+ * have been packed with it, these because of locality-of-reference may be read
+ * in the near future. Temporarily caching them ensures they are available for
+ * near future access without requiring an additional read and decompress.
+ */
+
+#include <linux/fs.h>
+#include <linux/vfs.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+#include <linux/wait.h>
+#include <linux/zlib.h>
+#include <linux/pagemap.h>
+
+#include "squashfs_fs.h"
+#include "squashfs_fs_sb.h"
+#include "squashfs_fs_i.h"
+#include "squashfs.h"
+
+/*
+ * Look-up block in cache, and increment usage count.  If not in cache, read
+ * and decompress it from disk.
+ */
+struct squashfs_cache_entry *squashfs_cache_get(struct super_block *sb,
+	struct squashfs_cache *cache, u64 block, int length)
+{
+	int i, n;
+	struct squashfs_cache_entry *entry;
+
+	spin_lock(&cache->lock);
+
+	while (1) {
+		for (i = 0; i < cache->entries; i++)
+			if (cache->entry[i].block == block)
+				break;
+
+		if (i == cache->entries) {
+			/*
+			 * Block not in cache, if all cache entries are used
+			 * go to sleep waiting for one to become available.
+			 */
+			if (cache->unused == 0) {
+				cache->num_waiters++;
+				spin_unlock(&cache->lock);
+				wait_event(cache->wait_queue, cache->unused);
+				spin_lock(&cache->lock);
+				cache->num_waiters--;
+				continue;
+			}
+
+			/*
+			 * At least one unused cache entry.  A simple
+			 * round-robin strategy is used to choose the entry to
+			 * be evicted from the cache.
+			 */
+			i = cache->next_blk;
+			for (n = 0; n < cache->entries; n++) {
+				if (cache->entry[i].refcount == 0)
+					break;
+				i = (i + 1) % cache->entries;
+			}
+
+			cache->next_blk = (i + 1) % cache->entries;
+			entry = &cache->entry[i];
+
+			/*
+			 * Initialise choosen cache entry, and fill it in from
+			 * disk.
+			 */
+			cache->unused--;
+			entry->block = block;
+			entry->refcount = 1;
+			entry->pending = 1;
+			entry->num_waiters = 0;
+			entry->error = 0;
+			spin_unlock(&cache->lock);
+
+			entry->length = squashfs_read_data(sb, entry->data,
+				block, length, &entry->next_index,
+				cache->block_size);
+
+			spin_lock(&cache->lock);
+
+			if (entry->length < 0)
+				entry->error = entry->length;
+
+			entry->pending = 0;
+
+			/*
+			 * While filling this entry one or more other processes
+			 * have looked it up in the cache, and have slept
+			 * waiting for it to become available.
+			 */
+			if (entry->num_waiters) {
+				spin_unlock(&cache->lock);
+				wake_up_all(&entry->wait_queue);
+			} else
+				spin_unlock(&cache->lock);
+
+			goto out;
+		}
+
+		/*
+		 * Block already in cache.  Increment refcount so it doesn't
+		 * get reused until we're finished with it, if it was
+		 * previously unused there's one less cache entry available
+		 * for reuse.
+		 */
+		entry = &cache->entry[i];
+		if (entry->refcount == 0)
+			cache->unused--;
+		entry->refcount++;
+
+		/*
+		 * If the entry is currently being filled in by another process
+		 * go to sleep waiting for it to become available.
+		 */
+		if (entry->pending) {
+			entry->num_waiters++;
+			spin_unlock(&cache->lock);
+			wait_event(entry->wait_queue, !entry->pending);
+		} else
+			spin_unlock(&cache->lock);
+
+		goto out;
+	}
+
+out:
+	TRACE("Got %s %d, start block %lld, refcount %d, error %d\n",
+		cache->name, i, entry->block, entry->refcount, entry->error);
+
+	if (entry->error)
+		ERROR("Unable to read %s cache entry [%llx]\n", cache->name,
+							block);
+	return entry;
+}
+
+
+/*
+ * Release cache entry, once usage count is zero it can be reused.
+ */
+void squashfs_cache_put(struct squashfs_cache_entry *entry)
+{
+	struct squashfs_cache *cache = entry->cache;
+
+	spin_lock(&cache->lock);
+	entry->refcount--;
+	if (entry->refcount == 0) {
+		cache->unused++;
+		/*
+		 * If there's any processes waiting for a block to become
+		 * available, wake one up.
+		 */
+		if (cache->num_waiters) {
+			spin_unlock(&cache->lock);
+			wake_up(&cache->wait_queue);
+			return;
+		}
+	}
+	spin_unlock(&cache->lock);
+}
+
+/*
+ * Delete cache reclaiming all kmalloced buffers.
+ */
+void squashfs_cache_delete(struct squashfs_cache *cache)
+{
+	int i, j;
+
+	if (cache == NULL)
+		return;
+
+	for (i = 0; i < cache->entries; i++) {
+		if (cache->entry[i].data) {
+			for (j = 0; j < cache->pages; j++)
+				kfree(cache->entry[i].data[j]);
+			kfree(cache->entry[i].data);
+		}
+	}
+
+	kfree(cache->entry);
+	kfree(cache);
+}
+
+
+/*
+ * Initialise cache allocating the specified number of entries, each of
+ * size block_size.  To avoid vmalloc fragmentation issues each entry
+ * is allocated as a sequence of kmalloced PAGE_CACHE_SIZE buffers.
+ */
+struct squashfs_cache *squashfs_cache_init(char *name, int entries,
+	int block_size)
+{
+	int i, j;
+	struct squashfs_cache *cache = kzalloc(sizeof(*cache), GFP_KERNEL);
+
+	if (cache == NULL) {
+		ERROR("Failed to allocate %s cache\n", name);
+		return NULL;
+	}
+
+	cache->entry = kcalloc(entries, sizeof(*(cache->entry)), GFP_KERNEL);
+	if (cache->entry == NULL) {
+		ERROR("Failed to allocate %s cache\n", name);
+		goto cleanup;
+	}
+
+	cache->next_blk = 0;
+	cache->unused = entries;
+	cache->entries = entries;
+	cache->block_size = block_size;
+	cache->pages = block_size >> PAGE_CACHE_SHIFT;
+	cache->name = name;
+	cache->num_waiters = 0;
+	spin_lock_init(&cache->lock);
+	init_waitqueue_head(&cache->wait_queue);
+
+	for (i = 0; i < entries; i++) {
+		struct squashfs_cache_entry *entry = &cache->entry[i];
+
+		init_waitqueue_head(&cache->entry[i].wait_queue);
+		entry->cache = cache;
+		entry->block = SQUASHFS_INVALID_BLK;
+		entry->data = kcalloc(cache->pages, sizeof(void *), GFP_KERNEL);
+		if (entry->data == NULL) {
+			ERROR("Failed to allocate %s cache entry\n", name);
+			goto cleanup;
+		}
+
+		for (j = 0; j < cache->pages; j++) {
+			entry->data[j] = kmalloc(PAGE_CACHE_SIZE, GFP_KERNEL);
+			if (entry->data[j] == NULL) {
+				ERROR("Failed to allocate %s buffer\n", name);
+				goto cleanup;
+			}
+		}
+	}
+
+	return cache;
+
+cleanup:
+	squashfs_cache_delete(cache);
+	return NULL;
+}
+
+
+/*
+ * Copy upto length bytes from cache entry to buffer starting at offset bytes
+ * into the cache entry.  If there's not length bytes then copy the number of
+ * bytes available.  In all cases return the number of bytes copied.
+ */
+int squashfs_copy_data(void *buffer, struct squashfs_cache_entry *entry,
+		int offset, int length)
+{
+	int remaining = length;
+
+	if (length == 0)
+		return 0;
+	else if (buffer == NULL)
+		return min(length, entry->length - offset);
+
+	while (offset < entry->length) {
+		void *buff = entry->data[offset / PAGE_CACHE_SIZE]
+				+ (offset % PAGE_CACHE_SIZE);
+		int bytes = min_t(int, entry->length - offset,
+				PAGE_CACHE_SIZE - (offset % PAGE_CACHE_SIZE));
+
+		if (bytes >= remaining) {
+			memcpy(buffer, buff, remaining);
+			remaining = 0;
+			break;
+		}
+
+		memcpy(buffer, buff, bytes);
+		buffer += bytes;
+		remaining -= bytes;
+		offset += bytes;
+	}
+
+	return length - remaining;
+}
+
+
+/*
+ * Read length bytes from metadata position <block, offset> (block is the
+ * start of the compressed block on disk, and offset is the offset into
+ * the block once decompressed).  Data is packed into consecutive blocks,
+ * and length bytes may require reading more than one block.
+ */
+int squashfs_read_metadata(struct super_block *sb, void *buffer,
+		u64 *block, int *offset, int length)
+{
+	struct squashfs_sb_info *msblk = sb->s_fs_info;
+	int bytes, copied = length;
+	struct squashfs_cache_entry *entry;
+
+	TRACE("Entered squashfs_read_metadata [%llx:%x]\n", *block, *offset);
+
+	while (length) {
+		entry = squashfs_cache_get(sb, msblk->block_cache, *block, 0);
+		if (entry->error)
+			return entry->error;
+		else if (*offset >= entry->length)
+			return -EIO;
+
+		bytes = squashfs_copy_data(buffer, entry, *offset, length);
+		if (buffer)
+			buffer += bytes;
+		length -= bytes;
+		*offset += bytes;
+
+		if (*offset == entry->length) {
+			*block = entry->next_index;
+			*offset = 0;
+		}
+
+		squashfs_cache_put(entry);
+	}
+
+	return copied;
+}
+
+
+/*
+ * Look-up in the fragmment cache the fragment located at <start_block> in the
+ * filesystem.  If necessary read and decompress it from disk.
+ */
+struct squashfs_cache_entry *squashfs_get_fragment(struct super_block *sb,
+				u64 start_block, int length)
+{
+	struct squashfs_sb_info *msblk = sb->s_fs_info;
+
+	return squashfs_cache_get(sb, msblk->fragment_cache, start_block,
+		length);
+}
+
+
+/*
+ * Read and decompress the datablock located at <start_block> in the
+ * filesystem.  The cache is used here to avoid duplicating locking and
+ * read/decompress code.
+ */
+struct squashfs_cache_entry *squashfs_get_datablock(struct super_block *sb,
+				u64 start_block, int length)
+{
+	struct squashfs_sb_info *msblk = sb->s_fs_info;
+
+	return squashfs_cache_get(sb, msblk->read_page, start_block, length);
+}
+
+
+/*
+ * Read a filesystem table (uncompressed sequence of bytes) from disk
+ */
+int squashfs_read_table(struct super_block *sb, void *buffer, u64 block,
+	int length)
+{
+	int pages = (length + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+	int i, res;
+	void **data = kcalloc(pages, sizeof(void *), GFP_KERNEL);
+	if (data == NULL)
+		return -ENOMEM;
+
+	for (i = 0; i < pages; i++, buffer += PAGE_CACHE_SIZE)
+		data[i] = buffer;
+	res = squashfs_read_data(sb, data, block, length |
+		SQUASHFS_COMPRESSED_BIT_BLOCK, NULL, length);
+	kfree(data);
+	return res;
+}

SQUASHFS/squashfs-tools-4.4/kernel/kernel-2.6/fs/squashfs/dir.c

+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
+ * Phillip Lougher <phillip@lougher.demon.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2,
+ * or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * dir.c
+ */
+
+/*
+ * This file implements code to read directories from disk.
+ *
+ * See namei.c for a description of directory organisation on disk.
+ */
+
+#include <linux/fs.h>
+#include <linux/vfs.h>
+#include <linux/slab.h>
+#include <linux/zlib.h>
+
+#include "squashfs_fs.h"
+#include "squashfs_fs_sb.h"
+#include "squashfs_fs_i.h"
+#include "squashfs.h"
+
+static const unsigned char squashfs_filetype_table[] = {
+	DT_UNKNOWN, DT_DIR, DT_REG, DT_LNK, DT_BLK, DT_CHR, DT_FIFO, DT_SOCK
+};
+
+/*
+ * Lookup offset (f_pos) in the directory index, returning the
+ * metadata block containing it.
+ *
+ * If we get an error reading the index then return the part of the index
+ * (if any) we have managed to read - the index isn't essential, just
+ * quicker.
+ */
+static int get_dir_index_using_offset(struct super_block *sb,
+	u64 *next_block, int *next_offset, u64 index_start, int index_offset,
+	int i_count, u64 f_pos)
+{
+	struct squashfs_sb_info *msblk = sb->s_fs_info;
+	int err, i, index, length = 0;
+	struct squashfs_dir_index dir_index;
+
+	TRACE("Entered get_dir_index_using_offset, i_count %d, f_pos %lld\n",
+					i_count, f_pos);
+
+	/*
+	 * Translate from external f_pos to the internal f_pos.  This
+	 * is offset by 3 because we invent "." and ".." entries which are
+	 * not actually stored in the directory.
+	 */
+	if (f_pos < 3)
+		return f_pos;
+	f_pos -= 3;
+
+	for (i = 0; i < i_count; i++) {
+		err = squashfs_read_metadata(sb, &dir_index, &index_start,
+				&index_offset, sizeof(dir_index));
+		if (err < 0)
+			break;
+
+		index = le32_to_cpu(dir_index.index);
+		if (index > f_pos)
+			/*
+			 * Found the index we're looking for.
+			 */
+			break;
+
+		err = squashfs_read_metadata(sb, NULL, &index_start,
+				&index_offset, le32_to_cpu(dir_index.size) + 1);
+		if (err < 0)
+			break;
+
+		length = index;
+		*next_block = le32_to_cpu(dir_index.start_block) +
+					msblk->directory_table;
+	}
+
+	*next_offset = (length + *next_offset) % SQUASHFS_METADATA_SIZE;
+
+	/*
+	 * Translate back from internal f_pos to external f_pos.
+	 */
+	return length + 3;
+}
+
+
+static int squashfs_readdir(struct file *file, void *dirent, filldir_t filldir)
+{
+	struct inode *inode = file->f_dentry->d_inode;
+	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
+	u64 block = squashfs_i(inode)->start + msblk->directory_table;
+	int offset = squashfs_i(inode)->offset, length = 0, dir_count, size,
+				type, err;
+	unsigned int inode_number;
+	struct squashfs_dir_header dirh;
+	struct squashfs_dir_entry *dire;
+
+	TRACE("Entered squashfs_readdir [%llx:%x]\n", block, offset);
+
+	dire = kmalloc(sizeof(*dire) + SQUASHFS_NAME_LEN + 1, GFP_KERNEL);
+	if (dire == NULL) {
+		ERROR("Failed to allocate squashfs_dir_entry\n");
+		goto finish;
+	}
+
+	/*
+	 * Return "." and  ".." entries as the first two filenames in the
+	 * directory.  To maximise compression these two entries are not
+	 * stored in the directory, and so we invent them here.
+	 *
+	 * It also means that the external f_pos is offset by 3 from the
+	 * on-disk directory f_pos.
+	 */
+	while (file->f_pos < 3) {
+		char *name;
+		int i_ino;
+
+		if (file->f_pos == 0) {
+			name = ".";
+			size = 1;
+			i_ino = inode->i_ino;
+		} else {
+			name = "..";
+			size = 2;
+			i_ino = squashfs_i(inode)->parent;
+		}
+
+		TRACE("Calling filldir(%p, %s, %d, %lld, %d, %d)\n",
+				dirent, name, size, file->f_pos, i_ino,
+				squashfs_filetype_table[1]);
+
+		if (filldir(dirent, name, size, file->f_pos, i_ino,
+				squashfs_filetype_table[1]) < 0) {
+				TRACE("Filldir returned less than 0\n");
+			goto finish;
+		}
+
+		file->f_pos += size;
+	}
+
+	length = get_dir_index_using_offset(inode->i_sb, &block, &offset,
+				squashfs_i(inode)->dir_idx_start,
+				squashfs_i(inode)->dir_idx_offset,
+				squashfs_i(inode)->dir_idx_cnt,
+				file->f_pos);
+
+	while (length < i_size_read(inode)) {
+		/*
+		 * Read directory header
+		 */
+		err = squashfs_read_metadata(inode->i_sb, &dirh, &block,
+					&offset, sizeof(dirh));
+		if (err < 0)
+			goto failed_read;
+
+		length += sizeof(dirh);
+
+		dir_count = le32_to_cpu(dirh.count) + 1;
+		while (dir_count--) {
+			/*
+			 * Read directory entry.
+			 */
+			err = squashfs_read_metadata(inode->i_sb, dire, &block,
+					&offset, sizeof(*dire));
+			if (err < 0)
+				goto failed_read;
+
+			size = le16_to_cpu(dire->size) + 1;
+
+			err = squashfs_read_metadata(inode->i_sb, dire->name,
+					&block, &offset, size);
+			if (err < 0)
+				goto failed_read;
+
+			length += sizeof(*dire) + size;
+
+			if (file->f_pos >= length)
+				continue;
+
+			dire->name[size] = '\0';
+			inode_number = le32_to_cpu(dirh.inode_number) +
+				((short) le16_to_cpu(dire->inode_number));
+			type = le16_to_cpu(dire->type);
+
+			TRACE("Calling filldir(%p, %s, %d, %lld, %x:%x, %d, %d)"
+					"\n", dirent, dire->name, size,
+					file->f_pos,
+					le32_to_cpu(dirh.start_block),
+					le16_to_cpu(dire->offset),
+					inode_number,
+					squashfs_filetype_table[type]);
+
+			if (filldir(dirent, dire->name, size, file->f_pos,
+					inode_number,
+					squashfs_filetype_table[type]) < 0) {
+				TRACE("Filldir returned less than 0\n");
+				goto finish;
+			}
+
+			file->f_pos = length;
+		}
+	}
+
+finish:
+	kfree(dire);
+	return 0;
+
+failed_read:
+	ERROR("Unable to read directory block [%llx:%x]\n", block, offset);
+	kfree(dire);
+	return 0;
+}
+
+
+const struct file_operations squashfs_dir_ops = {
+	.read = generic_read_dir,
+	.readdir = squashfs_readdir
+};

SQUASHFS/squashfs-tools-4.4/kernel/kernel-2.6/fs/squashfs/export.c

+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
+ * Phillip Lougher <phillip@lougher.demon.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2,
+ * or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * export.c
+ */
+
+/*
+ * This file implements code to make Squashfs filesystems exportable (NFS etc.)
+ *
+ * The export code uses an inode lookup table to map inode numbers passed in
+ * filehandles to an inode location on disk.  This table is stored compressed
+ * into metadata blocks.  A second index table is used to locate these.  This
+ * second index table for speed of access (and because it is small) is read at
+ * mount time and cached in memory.
+ *
+ * The inode lookup table is used only by the export code, inode disk
+ * locations are directly encoded in directories, enabling direct access
+ * without an intermediate lookup for all operations except the export ops.
+ */
+
+#include <linux/fs.h>
+#include <linux/vfs.h>
+#include <linux/dcache.h>
+#include <linux/exportfs.h>
+#include <linux/zlib.h>
+
+#include "squashfs_fs.h"
+#include "squashfs_fs_sb.h"
+#include "squashfs_fs_i.h"
+#include "squashfs.h"
+
+/*
+ * Look-up inode number (ino) in table, returning the inode location.
+ */
+static long long squashfs_inode_lookup(struct super_block *sb, int ino_num)
+{
+	struct squashfs_sb_info *msblk = sb->s_fs_info;
+	int blk = SQUASHFS_LOOKUP_BLOCK(ino_num - 1);
+	int offset = SQUASHFS_LOOKUP_BLOCK_OFFSET(ino_num - 1);
+	u64 start = le64_to_cpu(msblk->inode_lookup_table[blk]);
+	__le64 ino;
+	int err;
+
+	TRACE("Entered squashfs_inode_lookup, inode_number = %d\n", ino_num);
+
+	err = squashfs_read_metadata(sb, &ino, &start, &offset, sizeof(ino));
+	if (err < 0)
+		return err;
+
+	TRACE("squashfs_inode_lookup, inode = 0x%llx\n",
+		(u64) le64_to_cpu(ino));
+
+	return le64_to_cpu(ino);
+}
+
+
+static struct dentry *squashfs_export_iget(struct super_block *sb,
+	unsigned int ino_num)
+{
+	long long ino;
+	struct dentry *dentry = ERR_PTR(-ENOENT);
+
+	TRACE("Entered squashfs_export_iget\n");
+
+	ino = squashfs_inode_lookup(sb, ino_num);
+	if (ino >= 0)
+		dentry = d_obtain_alias(squashfs_iget(sb, ino, ino_num));
+
+	return dentry;
+}
+
+
+static struct dentry *squashfs_fh_to_dentry(struct super_block *sb,
+		struct fid *fid, int fh_len, int fh_type)
+{
+	if ((fh_type != FILEID_INO32_GEN && fh_type != FILEID_INO32_GEN_PARENT)
+			|| fh_len < 2)
+		return NULL;
+
+	return squashfs_export_iget(sb, fid->i32.ino);
+}
+
+
+static struct dentry *squashfs_fh_to_parent(struct super_block *sb,
+		struct fid *fid, int fh_len, int fh_type)
+{
+	if (fh_type != FILEID_INO32_GEN_PARENT || fh_len < 4)
+		return NULL;
+
+	return squashfs_export_iget(sb, fid->i32.parent_ino);
+}
+
+
+static struct dentry *squashfs_get_parent(struct dentry *child)
+{
+	struct inode *inode = child->d_inode;
+	unsigned int parent_ino = squashfs_i(inode)->parent;
+
+	return squashfs_export_iget(inode->i_sb, parent_ino);
+}
+
+
+/*
+ * Read uncompressed inode lookup table indexes off disk into memory
+ */
+__le64 *squashfs_read_inode_lookup_table(struct super_block *sb,
+		u64 lookup_table_start, unsigned int inodes)
+{
+	unsigned int length = SQUASHFS_LOOKUP_BLOCK_BYTES(inodes);
+	__le64 *inode_lookup_table;
+	int err;
+
+	TRACE("In read_inode_lookup_table, length %d\n", length);
+
+	/* Allocate inode lookup table indexes */
+	inode_lookup_table = kmalloc(length, GFP_KERNEL);
+	if (inode_lookup_table == NULL) {
+		ERROR("Failed to allocate inode lookup table\n");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	err = squashfs_read_table(sb, inode_lookup_table, lookup_table_start,
+			length);
+	if (err < 0) {
+		ERROR("unable to read inode lookup table\n");
+		kfree(inode_lookup_table);
+		return ERR_PTR(err);
+	}
+
+	return inode_lookup_table;
+}
+
+
+const struct export_operations squashfs_export_ops = {
+	.fh_to_dentry = squashfs_fh_to_dentry,
+	.fh_to_parent = squashfs_fh_to_parent,
+	.get_parent = squashfs_get_parent
+};

SQUASHFS/squashfs-tools-4.4/kernel/kernel-2.6/fs/squashfs/file.c

+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
+ * Phillip Lougher <phillip@lougher.demon.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2,
+ * or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * file.c
+ */
+
+/*
+ * This file contains code for handling regular files.  A regular file
+ * consists of a sequence of contiguous compressed blocks, and/or a
+ * compressed fragment block (tail-end packed block).   The compressed size
+ * of each datablock is stored in a block list contained within the
+ * file inode (itself stored in one or more compressed metadata blocks).
+ *
+ * To speed up access to datablocks when reading 'large' files (256 Mbytes or
+ * larger), the code implements an index cache that caches the mapping from
+ * block index to datablock location on disk.
+ *
+ * The index cache allows Squashfs to handle large files (up to 1.75 TiB) while
+ * retaining a simple and space-efficient block list on disk.  The cache
+ * is split into slots, caching up to eight 224 GiB files (128 KiB blocks).
+ * Larger files use multiple slots, with 1.75 TiB files using all 8 slots.
+ * The index cache is designed to be memory efficient, and by default uses
+ * 16 KiB.
+ */
+
+#include <linux/fs.h>
+#include <linux/vfs.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/pagemap.h>
+#include <linux/mutex.h>
+#include <linux/zlib.h>
+
+#include "squashfs_fs.h"
+#include "squashfs_fs_sb.h"
+#include "squashfs_fs_i.h"
+#include "squashfs.h"
+
+/*
+ * Locate cache slot in range [offset, index] for specified inode.  If
+ * there's more than one return the slot closest to index.
+ */
+static struct meta_index *locate_meta_index(struct inode *inode, int offset,
+				int index)
+{
+	struct meta_index *meta = NULL;
+	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
+	int i;
+
+	mutex_lock(&msblk->meta_index_mutex);
+
+	TRACE("locate_meta_index: index %d, offset %d\n", index, offset);
+
+	if (msblk->meta_index == NULL)
+		goto not_allocated;
+
+	for (i = 0; i < SQUASHFS_META_SLOTS; i++) {
+		if (msblk->meta_index[i].inode_number == inode->i_ino &&
+				msblk->meta_index[i].offset >= offset &&
+				msblk->meta_index[i].offset <= index &&
+				msblk->meta_index[i].locked == 0) {
+			TRACE("locate_meta_index: entry %d, offset %d\n", i,
+					msblk->meta_index[i].offset);
+			meta = &msblk->meta_index[i];
+			offset = meta->offset;
+		}
+	}
+
+	if (meta)
+		meta->locked = 1;
+
+not_allocated:
+	mutex_unlock(&msblk->meta_index_mutex);
+
+	return meta;
+}
+
+
+/*
+ * Find and initialise an empty cache slot for index offset.
+ */
+static struct meta_index *empty_meta_index(struct inode *inode, int offset,
+				int skip)
+{
+	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
+	struct meta_index *meta = NULL;
+	int i;
+
+	mutex_lock(&msblk->meta_index_mutex);
+
+	TRACE("empty_meta_index: offset %d, skip %d\n", offset, skip);
+
+	if (msblk->meta_index == NULL) {
+		/*
+		 * First time cache index has been used, allocate and
+		 * initialise.  The cache index could be allocated at
+		 * mount time but doing it here means it is allocated only
+		 * if a 'large' file is read.
+		 */
+		msblk->meta_index = kcalloc(SQUASHFS_META_SLOTS,
+			sizeof(*(msblk->meta_index)), GFP_KERNEL);
+		if (msblk->meta_index == NULL) {
+			ERROR("Failed to allocate meta_index\n");
+			goto failed;
+		}
+		for (i = 0; i < SQUASHFS_META_SLOTS; i++) {
+			msblk->meta_index[i].inode_number = 0;
+			msblk->meta_index[i].locked = 0;
+		}
+		msblk->next_meta_index = 0;
+	}
+
+	for (i = SQUASHFS_META_SLOTS; i &&
+			msblk->meta_index[msblk->next_meta_index].locked; i--)
+		msblk->next_meta_index = (msblk->next_meta_index + 1) %
+			SQUASHFS_META_SLOTS;
+
+	if (i == 0) {
+		TRACE("empty_meta_index: failed!\n");
+		goto failed;
+	}
+
+	TRACE("empty_meta_index: returned meta entry %d, %p\n",
+			msblk->next_meta_index,
+			&msblk->meta_index[msblk->next_meta_index]);
+
+	meta = &msblk->meta_index[msblk->next_meta_index];
+	msblk->next_meta_index = (msblk->next_meta_index + 1) %
+			SQUASHFS_META_SLOTS;
+
+	meta->inode_number = inode->i_ino;
+	meta->offset = offset;
+	meta->skip = skip;
+	meta->entries = 0;
+	meta->locked = 1;
+
+failed:
+	mutex_unlock(&msblk->meta_index_mutex);
+	return meta;
+}
+
+
+static void release_meta_index(struct inode *inode, struct meta_index *meta)
+{
+	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
+	mutex_lock(&msblk->meta_index_mutex);
+	meta->locked = 0;
+	mutex_unlock(&msblk->meta_index_mutex);
+}
+
+
+/*
+ * Read the next n blocks from the block list, starting from
+ * metadata block <start_block, offset>.
+ */
+static long long read_indexes(struct super_block *sb, int n,
+				u64 *start_block, int *offset)
+{
+	int err, i;
+	long long block = 0;
+	__le32 *blist = kmalloc(PAGE_CACHE_SIZE, GFP_KERNEL);
+
+	if (blist == NULL) {
+		ERROR("read_indexes: Failed to allocate block_list\n");
+		return -ENOMEM;
+	}
+
+	while (n) {
+		int blocks = min_t(int, n, PAGE_CACHE_SIZE >> 2);
+
+		err = squashfs_read_metadata(sb, blist, start_block,
+				offset, blocks << 2);
+		if (err < 0) {
+			ERROR("read_indexes: reading block [%llx:%x]\n",
+				*start_block, *offset);
+			goto failure;
+		}
+
+		for (i = 0; i < blocks; i++) {
+			int size = le32_to_cpu(blist[i]);
+			block += SQUASHFS_COMPRESSED_SIZE_BLOCK(size);
+		}
+		n -= blocks;
+	}
+
+	kfree(blist);
+	return block;
+
+failure:
+	kfree(blist);
+	return err;
+}
+
+
+/*
+ * Each cache index slot has SQUASHFS_META_ENTRIES, each of which
+ * can cache one index -> datablock/blocklist-block mapping.  We wish
+ * to distribute these over the length of the file, entry[0] maps index x,
+ * entry[1] maps index x + skip, entry[2] maps index x + 2 * skip, and so on.
+ * The larger the file, the greater the skip factor.  The skip factor is
+ * limited to the size of the metadata cache (SQUASHFS_CACHED_BLKS) to ensure
+ * the number of metadata blocks that need to be read fits into the cache.
+ * If the skip factor is limited in this way then the file will use multiple
+ * slots.
+ */
+static inline int calculate_skip(int blocks)
+{
+	int skip = blocks / ((SQUASHFS_META_ENTRIES + 1)
+		 * SQUASHFS_META_INDEXES);
+	return min(SQUASHFS_CACHED_BLKS - 1, skip + 1);
+}
+
+
+/*
+ * Search and grow the index cache for the specified inode, returning the
+ * on-disk locations of the datablock and block list metadata block
+ * <index_block, index_offset> for index (scaled to nearest cache index).
+ */
+static int fill_meta_index(struct inode *inode, int index,
+		u64 *index_block, int *index_offset, u64 *data_block)
+{
+	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
+	int skip = calculate_skip(i_size_read(inode) >> msblk->block_log);
+	int offset = 0;
+	struct meta_index *meta;
+	struct meta_entry *meta_entry;
+	u64 cur_index_block = squashfs_i(inode)->block_list_start;
+	int cur_offset = squashfs_i(inode)->offset;
+	u64 cur_data_block = squashfs_i(inode)->start;
+	int err, i;
+
+	/*
+	 * Scale index to cache index (cache slot entry)
+	 */
+	index /= SQUASHFS_META_INDEXES * skip;
+
+	while (offset < index) {
+		meta = locate_meta_index(inode, offset + 1, index);
+
+		if (meta == NULL) {
+			meta = empty_meta_index(inode, offset + 1, skip);
+			if (meta == NULL)
+				goto all_done;
+		} else {
+			offset = index < meta->offset + meta->entries ? index :
+				meta->offset + meta->entries - 1;
+			meta_entry = &meta->meta_entry[offset - meta->offset];
+			cur_index_block = meta_entry->index_block +
+				msblk->inode_table;
+			cur_offset = meta_entry->offset;
+			cur_data_block = meta_entry->data_block;
+			TRACE("get_meta_index: offset %d, meta->offset %d, "
+				"meta->entries %d\n", offset, meta->offset,
+				meta->entries);
+			TRACE("get_meta_index: index_block 0x%llx, offset 0x%x"
+				" data_block 0x%llx\n", cur_index_block,
+				cur_offset, cur_data_block);
+		}
+
+		/*
+		 * If necessary grow cache slot by reading block list.  Cache
+		 * slot is extended up to index or to the end of the slot, in
+		 * which case further slots will be used.
+		 */
+		for (i = meta->offset + meta->entries; i <= index &&
+				i < meta->offset + SQUASHFS_META_ENTRIES; i++) {
+			int blocks = skip * SQUASHFS_META_INDEXES;
+			long long res = read_indexes(inode->i_sb, blocks,
+					&cur_index_block, &cur_offset);
+
+			if (res < 0) {
+				if (meta->entries == 0)
+					/*
+					 * Don't leave an empty slot on read
+					 * error allocated to this inode...
+					 */
+					meta->inode_number = 0;
+				err = res;
+				goto failed;
+			}
+
+			cur_data_block += res;
+			meta_entry = &meta->meta_entry[i - meta->offset];
+			meta_entry->index_block = cur_index_block -
+				msblk->inode_table;
+			meta_entry->offset = cur_offset;
+			meta_entry->data_block = cur_data_block;
+			meta->entries++;
+			offset++;
+		}
+
+		TRACE("get_meta_index: meta->offset %d, meta->entries %d\n",
+				meta->offset, meta->entries);
+
+		release_meta_index(inode, meta);
+	}
+
+all_done:
+	*index_block = cur_index_block;
+	*index_offset = cur_offset;
+	*data_block = cur_data_block;
+
+	/*
+	 * Scale cache index (cache slot entry) to index
+	 */
+	return offset * SQUASHFS_META_INDEXES * skip;
+
+failed:
+	release_meta_index(inode, meta);
+	return err;
+}
+
+
+/*
+ * Get the on-disk location and compressed size of the datablock
+ * specified by index.  Fill_meta_index() does most of the work.
+ */
+static int read_blocklist(struct inode *inode, int index, u64 *block)
+{
+	u64 start;
+	long long blks;
+	int offset;
+	__le32 size;
+	int res = fill_meta_index(inode, index, &start, &offset, block);
+
+	TRACE("read_blocklist: res %d, index %d, start 0x%llx, offset"
+		       " 0x%x, block 0x%llx\n", res, index, start, offset,
+			*block);
+
+	if (res < 0)
+		return res;
+
+	/*
+	 * res contains the index of the mapping returned by fill_meta_index(),
+	 * this will likely be less than the desired index (because the
+	 * meta_index cache works at a higher granularity).  Read any
+	 * extra block indexes needed.
+	 */
+	if (res < index) {
+		blks = read_indexes(inode->i_sb, index - res, &start, &offset);
+		if (blks < 0)
+			return (int) blks;
+		*block += blks;
+	}
+
+	/*
+	 * Read length of block specified by index.
+	 */
+	res = squashfs_read_metadata(inode->i_sb, &size, &start, &offset,
+			sizeof(size));
+	if (res < 0)
+		return res;
+	return le32_to_cpu(size);
+}
+
+
+static int squashfs_readpage(struct file *file, struct page *page)
+{
+	struct inode *inode = page->mapping->host;
+	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
+	int bytes, i, offset = 0, sparse = 0;
+	struct squashfs_cache_entry *buffer = NULL;
+	void *pageaddr;
+
+	int mask = (1 << (msblk->block_log - PAGE_CACHE_SHIFT)) - 1;
+	int index = page->index >> (msblk->block_log - PAGE_CACHE_SHIFT);
+	int start_index = page->index & ~mask;
+	int end_index = start_index | mask;
+	int file_end = i_size_read(inode) >> msblk->block_log;
+
+	TRACE("Entered squashfs_readpage, page index %lx, start block %llx\n",
+				page->index, squashfs_i(inode)->start);
+
+	if (page->index >= ((i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
+					PAGE_CACHE_SHIFT))
+		goto out;
+
+	if (index < file_end || squashfs_i(inode)->fragment_block ==
+					SQUASHFS_INVALID_BLK) {
+		/*
+		 * Reading a datablock from disk.  Need to read block list
+		 * to get location and block size.
+		 */
+		u64 block = 0;
+		int bsize = read_blocklist(inode, index, &block);
+		if (bsize < 0)
+			goto error_out;
+
+		if (bsize == 0) { /* hole */
+			bytes = index == file_end ?
+				(i_size_read(inode) & (msblk->block_size - 1)) :
+				 msblk->block_size;
+			sparse = 1;
+		} else {
+			/*
+			 * Read and decompress datablock.
+			 */
+			buffer = squashfs_get_datablock(inode->i_sb,
+								block, bsize);
+			if (buffer->error) {
+				ERROR("Unable to read page, block %llx, size %x"
+					"\n", block, bsize);
+				squashfs_cache_put(buffer);
+				goto error_out;
+			}
+			bytes = buffer->length;
+		}
+	} else {
+		/*
+		 * Datablock is stored inside a fragment (tail-end packed
+		 * block).
+		 */
+		buffer = squashfs_get_fragment(inode->i_sb,
+				squashfs_i(inode)->fragment_block,
+				squashfs_i(inode)->fragment_size);
+
+		if (buffer->error) {
+			ERROR("Unable to read page, block %llx, size %x\n",
+				squashfs_i(inode)->fragment_block,
+				squashfs_i(inode)->fragment_size);
+			squashfs_cache_put(buffer);
+			goto error_out;
+		}
+		bytes = i_size_read(inode) & (msblk->block_size - 1);
+		offset = squashfs_i(inode)->fragment_offset;
+	}
+
+	/*
+	 * Loop copying datablock into pages.  As the datablock likely covers
+	 * many PAGE_CACHE_SIZE pages (default block size is 128 KiB) explicitly
+	 * grab the pages from the page cache, except for the page that we've
+	 * been called to fill.
+	 */
+	for (i = start_index; i <= end_index && bytes > 0; i++,
+			bytes -= PAGE_CACHE_SIZE, offset += PAGE_CACHE_SIZE) {
+		struct page *push_page;
+		int avail = sparse ? 0 : min_t(int, bytes, PAGE_CACHE_SIZE);
+
+		TRACE("bytes %d, i %d, available_bytes %d\n", bytes, i, avail);
+
+		push_page = (i == page->index) ? page :
+			grab_cache_page_nowait(page->mapping, i);
+
+		if (!push_page)
+			continue;
+
+		if (PageUptodate(push_page))
+			goto skip_page;
+
+		pageaddr = kmap_atomic(push_page, KM_USER0);
+		squashfs_copy_data(pageaddr, buffer, offset, avail);
+		memset(pageaddr + avail, 0, PAGE_CACHE_SIZE - avail);
+		kunmap_atomic(pageaddr, KM_USER0);
+		flush_dcache_page(push_page);
+		SetPageUptodate(push_page);
+skip_page:
+		unlock_page(push_page);
+		if (i != page->index)
+			page_cache_release(push_page);
+	}
+
+	if (!sparse)
+		squashfs_cache_put(buffer);
+
+	return 0;
+
+error_out:
+	SetPageError(page);
+out:
+	pageaddr = kmap_atomic(page, KM_USER0);
+	memset(pageaddr, 0, PAGE_CACHE_SIZE);
+	kunmap_atomic(pageaddr, KM_USER0);
+	flush_dcache_page(page);
+	if (!PageError(page))
+		SetPageUptodate(page);
+	unlock_page(page);
+
+	return 0;
+}
+
+
+const struct address_space_operations squashfs_aops = {
+	.readpage = squashfs_readpage
+};

SQUASHFS/squashfs-tools-4.4/kernel/kernel-2.6/fs/squashfs/fragment.c

+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
+ * Phillip Lougher <phillip@lougher.demon.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2,
+ * or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * fragment.c
+ */
+
+/*
+ * This file implements code to handle compressed fragments (tail-end packed
+ * datablocks).
+ *
+ * Regular files contain a fragment index which is mapped to a fragment
+ * location on disk and compressed size using a fragment lookup table.
+ * Like everything in Squashfs this fragment lookup table is itself stored
+ * compressed into metadata blocks.  A second index table is used to locate
+ * these.  This second index table for speed of access (and because it
+ * is small) is read at mount time and cached in memory.
+ */
+
+#include <linux/fs.h>
+#include <linux/vfs.h>
+#include <linux/slab.h>
+#include <linux/zlib.h>
+
+#include "squashfs_fs.h"
+#include "squashfs_fs_sb.h"
+#include "squashfs_fs_i.h"
+#include "squashfs.h"
+
+/*
+ * Look-up fragment using the fragment index table.  Return the on disk
+ * location of the fragment and its compressed size
+ */
+int squashfs_frag_lookup(struct super_block *sb, unsigned int fragment,
+				u64 *fragment_block)
+{
+	struct squashfs_sb_info *msblk = sb->s_fs_info;
+	int block = SQUASHFS_FRAGMENT_INDEX(fragment);
+	int offset = SQUASHFS_FRAGMENT_INDEX_OFFSET(fragment);
+	u64 start_block = le64_to_cpu(msblk->fragment_index[block]);
+	struct squashfs_fragment_entry fragment_entry;
+	int size;
+
+	size = squashfs_read_metadata(sb, &fragment_entry, &start_block,
+					&offset, sizeof(fragment_entry));
+	if (size < 0)
+		return size;
+
+	*fragment_block = le64_to_cpu(fragment_entry.start_block);
+	size = le32_to_cpu(fragment_entry.size);
+
+	return size;
+}
+
+
+/*
+ * Read the uncompressed fragment lookup table indexes off disk into memory
+ */
+__le64 *squashfs_read_fragment_index_table(struct super_block *sb,
+	u64 fragment_table_start, unsigned int fragments)
+{
+	unsigned int length = SQUASHFS_FRAGMENT_INDEX_BYTES(fragments);
+	__le64 *fragment_index;
+	int err;
+
+	/* Allocate fragment lookup table indexes */
+	fragment_index = kmalloc(length, GFP_KERNEL);
+	if (fragment_index == NULL) {
+		ERROR("Failed to allocate fragment index table\n");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	err = squashfs_read_table(sb, fragment_index, fragment_table_start,
+			length);
+	if (err < 0) {
+		ERROR("unable to read fragment index table\n");
+		kfree(fragment_index);
+		return ERR_PTR(err);
+	}
+
+	return fragment_index;
+}

SQUASHFS/squashfs-tools-4.4/kernel/kernel-2.6/fs/squashfs/id.c

+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
+ * Phillip Lougher <phillip@lougher.demon.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2,
+ * or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * id.c
+ */
+
+/*
+ * This file implements code to handle uids and gids.
+ *
+ * For space efficiency regular files store uid and gid indexes, which are
+ * converted to 32-bit uids/gids using an id look up table.  This table is
+ * stored compressed into metadata blocks.  A second index table is used to
+ * locate these.  This second index table for speed of access (and because it
+ * is small) is read at mount time and cached in memory.
+ */
+
+#include <linux/fs.h>
+#include <linux/vfs.h>
+#include <linux/slab.h>
+#include <linux/zlib.h>
+
+#include "squashfs_fs.h"
+#include "squashfs_fs_sb.h"
+#include "squashfs_fs_i.h"
+#include "squashfs.h"
+
+/*
+ * Map uid/gid index into real 32-bit uid/gid using the id look up table
+ */
+int squashfs_get_id(struct super_block *sb, unsigned int index,
+					unsigned int *id)
+{
+	struct squashfs_sb_info *msblk = sb->s_fs_info;
+	int block = SQUASHFS_ID_BLOCK(index);
+	int offset = SQUASHFS_ID_BLOCK_OFFSET(index);
+	u64 start_block = le64_to_cpu(msblk->id_table[block]);
+	__le32 disk_id;
+	int err;
+
+	err = squashfs_read_metadata(sb, &disk_id, &start_block, &offset,
+							sizeof(disk_id));
+	if (err < 0)
+		return err;
+
+	*id = le32_to_cpu(disk_id);
+	return 0;
+}
+
+
+/*
+ * Read uncompressed id lookup table indexes from disk into memory
+ */
+__le64 *squashfs_read_id_index_table(struct super_block *sb,
+			u64 id_table_start, unsigned short no_ids)
+{
+	unsigned int length = SQUASHFS_ID_BLOCK_BYTES(no_ids);
+	__le64 *id_table;
+	int err;
+
+	TRACE("In read_id_index_table, length %d\n", length);
+
+	/* Allocate id lookup table indexes */
+	id_table = kmalloc(length, GFP_KERNEL);
+	if (id_table == NULL) {
+		ERROR("Failed to allocate id index table\n");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	err = squashfs_read_table(sb, id_table, id_table_start, length);
+	if (err < 0) {
+		ERROR("unable to read id index table\n");
+		kfree(id_table);
+		return ERR_PTR(err);
+	}
+
+	return id_table;
+}