The decompressor interface and code was written from
the point of view of single-threaded operation.  In doing
so it mixed a lot of single-threaded implementation specific
aspects into the decompressor code and elsewhere which makes it
difficult to seamlessly support multiple different decompressor
implementations.

This patch does the following:

1.  It removes compressor_options parsing from the decompressor
    init() function.  This allows the decompressor init() function
    to be dynamically called to instantiate multiple decompressors,
    without the compressor options needing to be read and parsed each
    time.

2.  It moves threading and all sleeping operations out of the
    decompressors.  In doing so, it makes the decompressors
    non-blocking wrappers which only deal with interfacing with
    the decompressor implementation.

3. It splits decompressor.[ch] into decompressor generic functions
   in decompressor.[ch], and moves the single threaded
   decompressor implementation into decompressor_single.c.

The result of this patch is Squashfs should now be able to
support multiple decompressors by adding new decompressor_xxx.c
files with specialised implementations of the functions in
decompressor_single.c
Signed-off-by: NPhillip Lougher <phillip@squashfs.org.uk>
Reviewed-by: NMinchan Kim <minchan@kernel.org>

Squashfs now supports XZ and LZO compression in addition to ZLIB.
As such it no longer makes sense to always include ZLIB support.
In particular embedded systems may only use LZO or XZ compression, and
the ability to exclude ZLIB support will reduce kernel size.
Signed-off-by: NPhillip Lougher <phillip@squashfs.org.uk>

My existing email address may stop working in a month or two, so update
email to one that will continue working.
Signed-off-by: NPhillip Lougher <phillip@lougher.demon.co.uk>

Fsfuzzer generates corrupted filesystems which throw a warn_on in
kmalloc.  One of these is due to a corrupted superblock fragments field.
Fix this by checking that the number of bytes to be read (and allocated)
does not extend into the next filesystem structure.

Also add a couple of other sanity checks of the mount-time fragment table
structures.
Signed-off-by: NPhillip Lougher <phillip@lougher.demon.co.uk>

Fsfuzzer generates corrupted filesystems which throw a warn_on in
kmalloc.  One of these is due to a corrupted superblock inodes field.
Fix this by checking that the number of bytes to be read (and allocated)
does not extend into the next filesystem structure.

Also add a couple of other sanity checks of the mount-time lookup table
structures.
Signed-off-by: NPhillip Lougher <phillip@lougher.demon.co.uk>

Fsfuzzer generates corrupted filesystems which throw a warn_on in
kmalloc.  One of these is due to a corrupted superblock no_ids field.
Fix this by checking that the number of bytes to be read (and allocated)
does not extend into the next filesystem structure.

Also add a couple of other sanity checks of the mount-time id table
structures.
Signed-off-by: NPhillip Lougher <phillip@lougher.demon.co.uk>

This eliminates a lot of duplicate code.
Signed-off-by: NPhillip Lougher <phillip@lougher.demon.co.uk>

Extend decompressor framework to handle compression options stored in
the filesystem.  These options can be used by the relevant decompressor
at initialisation time to over-ride defaults.

The presence of compression options in the filesystem is indicated by
the COMP_OPT filesystem flag.  If present the data is read from the
filesystem and passed to the decompressor init function.  The decompressor
init function signature has been extended to take this data.

Also update the init function signature in the glib, lzo and xz
decompressor wrappers.
Signed-off-by: NPhillip Lougher <phillip@lougher.demon.co.uk>

Get rid of messy repeated #if(n)def CONFIG_SQUASHFS_LZO code
in decompressor.c
Signed-off-by: NPhillip Lougher <phillip@lougher.demon.co.uk>

Move squashfs_i() definition out of squashfs.h, this eliminates
the need to #include squashfs_fs_i.h from numerous files.
Signed-off-by: NPhillip Lougher <phillip@lougher.demon.co.uk>

Signed-off-by: NPhillip Lougher <phillip@lougher.demon.co.uk>

Signed-off-by: NChan Jeong <chan.jeong@lge.com>
Signed-off-by: NPhillip Lougher <phillip@lougher.demon.co.uk>

Signed-off-by: NPhillip Lougher <phillip@lougher.demon.co.uk>

Signed-off-by: NPhillip Lougher <phillip@lougher.demon.co.uk>

Add new extended inode types that store the xattr_id field.
Also add the necessary code changes to make xattrs visibile.
Signed-off-by: NPhillip Lougher <phillip@lougher.demon.co.uk>

This patch adds support for mapping xattr ids (stored in inodes)
into the on-disk location of the xattrs themselves.
Signed-off-by: NPhillip Lougher <phillip@lougher.demon.co.uk>

This adds a decompressor framework which allows multiple compression
algorithms to be cleanly supported.

Also update zlib wrapper and other code to use the new framework.
Signed-off-by: NPhillip Lougher <phillip@lougher.demon.co.uk>

Move zlib buffer init/destroy code into separate wrapper file.  Also
make zlib z_stream field a void * removing the need to include zlib.h
for most files.
Signed-off-by: NPhillip Lougher <phillip@lougher.demon.co.uk>

Signed-off-by: NPhillip Lougher <phillip@lougher.demon.co.uk>

This fixes a code regression caused by the recent mainlining changes.
The recent code changes call zlib_inflate repeatedly, decompressing into
separate 4K buffers, this code didn't check for the possibility that
zlib_inflate might ask for too many buffers when decompressing corrupted
data.
Signed-off-by: NPhillip Lougher <phillip@lougher.demon.co.uk>

Signed-off-by: NPhillip Lougher <phillip@lougher.demon.co.uk>