commit eabac19e40 upstream.
Sysbot has reported an "slab-out-of-bounds read" error which has been
identified as being caused by a corrupted "ino_num" value read from the
inode. This could be because the metadata block is uncompressed, or
because the "compression" bit has been corrupted (turning a compressed
block into an uncompressed block).
This patch adds additional sanity checks to detect this, and the
following corruption.
1. It checks against corruption of the inodes count. This can either
lead to a larger table to be read, or a smaller than expected
table to be read.
In the case of a too large inodes count, this would often have been
trapped by the existing sanity checks, but this patch introduces
a more exact check, which can identify too small values.
2. It checks the contents of the index table for corruption.
[phillip@squashfs.org.uk: fix checkpatch issue]
Link: https://lkml.kernel.org/r/527909353.754618.1612769948607@webmail.123-reg.co.uk
Link: https://lkml.kernel.org/r/20210204130249.4495-4-phillip@squashfs.org.uk
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Reported-by: syzbot+04419e3ff19d2970ea28@syzkaller.appspotmail.com
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit cdbb65c4c7 ]
Anatoly continues to find issues with fuzzed squashfs images.
This time, corrupt, missing, or undersized data for the page filling
wasn't checked for, because the squashfs_{copy,read}_cache() functions
did the squashfs_copy_data() call without checking the resulting data
size.
Which could result in the page cache pages being incompletely filled in,
and no error indication to the user space reading garbage data.
So make a helper function for the "fill in pages" case, because the
exact same incomplete sequence existed in two places.
[ I should have made a squashfs branch for these things, but I didn't
intend to start doing them in the first place.
My historical connection through cramfs is why I got into looking at
these issues at all, and every time I (continue to) think it's a
one-off.
Because _this_ time is always the last time. Right? - Linus ]
Reported-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com>
Tested-by: Willy Tarreau <w@1wt.eu>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Phillip Lougher <phillip@squashfs.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 71755ee535 upstream.
The squashfs fragment reading code doesn't actually verify that the
fragment is inside the fragment table. The end result _is_ verified to
be inside the image when actually reading the fragment data, but before
that is done, we may end up taking a page fault because the fragment
table itself might not even exist.
Another report from Anatoly and his endless squashfs image fuzzing.
Reported-by: Анатолий Тросиненко <anatoly.trosinenko@gmail.com>
Acked-by:: Phillip Lougher <phillip.lougher@gmail.com>,
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 01cfb7937a upstream.
Anatoly Trosinenko reports that a corrupted squashfs image can cause a
kernel oops. It turns out that squashfs can end up being confused about
negative fragment lengths.
The regular squashfs_read_data() does check for negative lengths, but
squashfs_read_metadata() did not, and the fragment size code just
blindly trusted the on-disk value. Fix both the fragment parsing and
the metadata reading code.
Reported-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Phillip Lougher <phillip@squashfs.org.uk>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
PD#SWPL-37734
Problem:
crash in fs if put page reference count
Solution:
1, remove modify of put page;
2, revert following changes introduced by google:
commit 60cc09a9e3
Author: Adrien Schildknecht <adriens@google.com>
Date: Thu Sep 29 15:25:30 2016 -0700
ANDROID: Squashfs: optimize reading uncompressed data
When dealing with uncompressed data, there is no need to read a whole
block (default 128K) to get the desired page: the pages are
independent from each others.
This patch change the readpages logic so that reading uncompressed
data only read the number of pages advised by the readahead algorithm.
Moreover, if the page actor contains holes (i.e. pages that are already
up-to-date), squashfs skips the buffer_head associated to those pages.
This patch greatly improve the performance of random reads for
uncompressed files because squashfs only read what is needed. It also
reduces the number of unnecessary reads.
Change-Id: I90a77343bb994a1de7482eb43eaf6d2021502c22
Signed-off-by: Adrien Schildknecht <adriens@google.com>
---------------------------------------------------
commit d840c1d772
Author: Adrien Schildknecht <adrien+dev@schischi.me>
Date: Fri Oct 14 21:03:54 2016 -0700
ANDROID: Squashfs: implement .readpages()
Squashfs does not implement .readpages(), so the kernel just repeatedly
calls .readpage().
The readpages function tries to pack as much pages as possible in the
same page actor so that only 1 read request is issued.
Now that the read requests are asynchronous, the kernel can truly
prefetch pages using its readahead algorithm.
Change-Id: I65b9aa2ddc9444aaf9ccf60781172ccca0f3f518
Signed-off-by: Adrien Schildknecht <adriens@google.com>
---------------------------------------------------
ANDROID: Squashfs: replace buffer_head with BIO
The 'll_rw_block' has been deprecated and BIO is now the basic container
for block I/O within the kernel.
Switching to BIO offers 2 advantages:
1/ It removes synchronous wait for the up-to-date buffers: SquashFS
now deals with decompressions/copies asynchronously.
Implementing an asynchronous mechanism to read data is needed to
efficiently implement .readpages().
2/ Prior to this patch, merging the read requests entirely depends on
the IO scheduler. SquashFS has more information than the IO
scheduler about what could be merged. Moreover, merging the reads
at the FS level means that we rely less on the IO scheduler.
Change-Id: I668812cc1e78e2f92497f9ebe0157cb8eec725ba
Signed-off-by: Adrien Schildknecht <adriens@google.com>
Verify:
t318
Change-Id: I9ea62393066122cd720f41d50bde6cdf925fb06a
Signed-off-by: Tao Zeng <tao.zeng@amlogic.com>
PD#SWPL-37734
Problem:
cma allocation failed when work with squashfs.
Solution:
release page ref# for squashfs to work with CMA
Verify:
t318
Signed-off-by: Tao Zeng <tao.zeng@amlogic.com>
Change-Id: I5d3b8afcc917d83472eeba70f131fd6b8f8f4836
When dealing with uncompressed data, there is no need to read a whole
block (default 128K) to get the desired page: the pages are
independent from each others.
This patch change the readpages logic so that reading uncompressed
data only read the number of pages advised by the readahead algorithm.
Moreover, if the page actor contains holes (i.e. pages that are already
up-to-date), squashfs skips the buffer_head associated to those pages.
This patch greatly improve the performance of random reads for
uncompressed files because squashfs only read what is needed. It also
reduces the number of unnecessary reads.
Change-Id: I90a77343bb994a1de7482eb43eaf6d2021502c22
Signed-off-by: Adrien Schildknecht <adriens@google.com>
Squashfs does not implement .readpages(), so the kernel just repeatedly
calls .readpage().
The readpages function tries to pack as much pages as possible in the
same page actor so that only 1 read request is issued.
Now that the read requests are asynchronous, the kernel can truly
prefetch pages using its readahead algorithm.
Change-Id: I65b9aa2ddc9444aaf9ccf60781172ccca0f3f518
Signed-off-by: Adrien Schildknecht <adriens@google.com>
The 'll_rw_block' has been deprecated and BIO is now the basic container
for block I/O within the kernel.
Switching to BIO offers 2 advantages:
1/ It removes synchronous wait for the up-to-date buffers: SquashFS
now deals with decompressions/copies asynchronously.
Implementing an asynchronous mechanism to read data is needed to
efficiently implement .readpages().
2/ Prior to this patch, merging the read requests entirely depends on
the IO scheduler. SquashFS has more information than the IO
scheduler about what could be merged. Moreover, merging the reads
at the FS level means that we rely less on the IO scheduler.
Change-Id: I668812cc1e78e2f92497f9ebe0157cb8eec725ba
Signed-off-by: Adrien Schildknecht <adriens@google.com>
This patch essentially does 3 things:
1/ Always use an array of page to store the data instead of a mix of
buffers and pages.
2/ It is now possible to have 'holes' in a page actor, i.e. NULL
pages in the array.
When reading a block (default 128K), squashfs tries to grab all
the pages covering this block. If a single page is up-to-date or
locked, it falls back to using an intermediate buffer to do the
read and then copy the pages in the actor. Allowing holes in the
page actor remove the need for this intermediate buffer.
3/ Refactor the wrappers to share code that deals with page actors.
Change-Id: I975801b32966b7ea930aebbb32d1b77233d2d2ce
Signed-off-by: Adrien Schildknecht <adriens@google.com>
FILE_DIRECT is working fine and offers faster results and lower memory
footprint.
Removing FILE_CACHE makes our life easier because we don't have to
maintain 2 differents function that does the same thing.
Change-Id: Ib11dfeb6847fb79d166e10686a95eabb8c65710a
Signed-off-by: Adrien Schildknecht <adriens@google.com>
This has ll_rw_block users pass in the operation and flags separately,
so ll_rw_block can setup the bio op and bi_rw flags on the bio that
is submitted.
Signed-off-by: Mike Christie <mchristi@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time
ago with promise that one day it will be possible to implement page
cache with bigger chunks than PAGE_SIZE.
This promise never materialized. And unlikely will.
We have many places where PAGE_CACHE_SIZE assumed to be equal to
PAGE_SIZE. And it's constant source of confusion on whether
PAGE_CACHE_* or PAGE_* constant should be used in a particular case,
especially on the border between fs and mm.
Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much
breakage to be doable.
Let's stop pretending that pages in page cache are special. They are
not.
The changes are pretty straight-forward:
- <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
- <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
- PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN};
- page_cache_get() -> get_page();
- page_cache_release() -> put_page();
This patch contains automated changes generated with coccinelle using
script below. For some reason, coccinelle doesn't patch header files.
I've called spatch for them manually.
The only adjustment after coccinelle is revert of changes to
PAGE_CAHCE_ALIGN definition: we are going to drop it later.
There are few places in the code where coccinelle didn't reach. I'll
fix them manually in a separate patch. Comments and documentation also
will be addressed with the separate patch.
virtual patch
@@
expression E;
@@
- E << (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E
@@
expression E;
@@
- E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E
@@
@@
- PAGE_CACHE_SHIFT
+ PAGE_SHIFT
@@
@@
- PAGE_CACHE_SIZE
+ PAGE_SIZE
@@
@@
- PAGE_CACHE_MASK
+ PAGE_MASK
@@
expression E;
@@
- PAGE_CACHE_ALIGN(E)
+ PAGE_ALIGN(E)
@@
expression E;
@@
- page_cache_get(E)
+ get_page(E)
@@
expression E;
@@
- page_cache_release(E)
+ put_page(E)
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Mark those kmem allocations that are known to be easily triggered from
userspace as __GFP_ACCOUNT/SLAB_ACCOUNT, which makes them accounted to
memcg. For the list, see below:
- threadinfo
- task_struct
- task_delay_info
- pid
- cred
- mm_struct
- vm_area_struct and vm_region (nommu)
- anon_vma and anon_vma_chain
- signal_struct
- sighand_struct
- fs_struct
- files_struct
- fdtable and fdtable->full_fds_bits
- dentry and external_name
- inode for all filesystems. This is the most tedious part, because
most filesystems overwrite the alloc_inode method.
The list is far from complete, so feel free to add more objects.
Nevertheless, it should be close to "account everything" approach and
keep most workloads within bounds. Malevolent users will be able to
breach the limit, but this was possible even with the former "account
everything" approach (simply because it did not account everything in
fact).
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Greg Thelen <gthelen@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull misc vfs updates from Al Viro:
"All kinds of stuff. That probably should've been 5 or 6 separate
branches, but by the time I'd realized how large and mixed that bag
had become it had been too close to -final to play with rebasing.
Some fs/namei.c cleanups there, memdup_user_nul() introduction and
switching open-coded instances, burying long-dead code, whack-a-mole
of various kinds, several new helpers for ->llseek(), assorted
cleanups and fixes from various people, etc.
One piece probably deserves special mention - Neil's
lookup_one_len_unlocked(). Similar to lookup_one_len(), but gets
called without ->i_mutex and tries to avoid ever taking it. That, of
course, means that it's not useful for any directory modifications,
but things like getting inode attributes in nfds readdirplus are fine
with that. I really should've asked for moratorium on lookup-related
changes this cycle, but since I hadn't done that early enough... I
*am* asking for that for the coming cycle, though - I'm going to try
and get conversion of i_mutex to rwsem with ->lookup() done under lock
taken shared.
There will be a patch closer to the end of the window, along the lines
of the one Linus had posted last May - mechanical conversion of
->i_mutex accesses to inode_lock()/inode_unlock()/inode_trylock()/
inode_is_locked()/inode_lock_nested(). To quote Linus back then:
-----
| This is an automated patch using
|
| sed 's/mutex_lock(&\(.*\)->i_mutex)/inode_lock(\1)/'
| sed 's/mutex_unlock(&\(.*\)->i_mutex)/inode_unlock(\1)/'
| sed 's/mutex_lock_nested(&\(.*\)->i_mutex,[ ]*I_MUTEX_\([A-Z0-9_]*\))/inode_lock_nested(\1, I_MUTEX_\2)/'
| sed 's/mutex_is_locked(&\(.*\)->i_mutex)/inode_is_locked(\1)/'
| sed 's/mutex_trylock(&\(.*\)->i_mutex)/inode_trylock(\1)/'
|
| with a very few manual fixups
-----
I'm going to send that once the ->i_mutex-affecting stuff in -next
gets mostly merged (or when Linus says he's about to stop taking
merges)"
* 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (63 commits)
nfsd: don't hold i_mutex over userspace upcalls
fs:affs:Replace time_t with time64_t
fs/9p: use fscache mutex rather than spinlock
proc: add a reschedule point in proc_readfd_common()
logfs: constify logfs_block_ops structures
fcntl: allow to set O_DIRECT flag on pipe
fs: __generic_file_splice_read retry lookup on AOP_TRUNCATED_PAGE
fs: xattr: Use kvfree()
[s390] page_to_phys() always returns a multiple of PAGE_SIZE
nbd: use ->compat_ioctl()
fs: use block_device name vsprintf helper
lib/vsprintf: add %*pg format specifier
fs: use gendisk->disk_name where possible
poll: plug an unused argument to do_poll
amdkfd: don't open-code memdup_user()
cdrom: don't open-code memdup_user()
rsxx: don't open-code memdup_user()
mtip32xx: don't open-code memdup_user()
[um] mconsole: don't open-code memdup_user_nul()
[um] hostaudio: don't open-code memdup_user()
...
Pull vfs xattr updates from Al Viro:
"Andreas' xattr cleanup series.
It's a followup to his xattr work that went in last cycle; -0.5KLoC"
* 'work.xattr' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
xattr handlers: Simplify list operation
ocfs2: Replace list xattr handler operations
nfs: Move call to security_inode_listsecurity into nfs_listxattr
xfs: Change how listxattr generates synthetic attributes
tmpfs: listxattr should include POSIX ACL xattrs
tmpfs: Use xattr handler infrastructure
btrfs: Use xattr handler infrastructure
vfs: Distinguish between full xattr names and proper prefixes
posix acls: Remove duplicate xattr name definitions
gfs2: Remove gfs2_xattr_acl_chmod
vfs: Remove vfs_xattr_cmp
Change the list operation to only return whether or not an attribute
should be listed. Copying the attribute names into the buffer is moved
to the callers.
Since the result only depends on the dentry and not on the attribute
name, we do not pass the attribute name to list operations.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
new method: ->get_link(); replacement of ->follow_link(). The differences
are:
* inode and dentry are passed separately
* might be called both in RCU and non-RCU mode;
the former is indicated by passing it a NULL dentry.
* when called that way it isn't allowed to block
and should return ERR_PTR(-ECHILD) if it needs to be called
in non-RCU mode.
It's a flagday change - the old method is gone, all in-tree instances
converted. Conversion isn't hard; said that, so far very few instances
do not immediately bail out when called in RCU mode. That'll change
in the next commits.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
kmap() in page_follow_link_light() needed to go - allowing to hold
an arbitrary number of kmaps for long is a great way to deadlocking
the system.
new helper (inode_nohighmem(inode)) needs to be used for pagecache
symlinks inodes; done for all in-tree cases. page_follow_link_light()
instrumented to yell about anything missed.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Add an additional "name" field to struct xattr_handler. When the name
is set, the handler matches attributes with exactly that name. When the
prefix is set instead, the handler matches attributes with the given
prefix and with a non-empty suffix.
This patch should avoid bugs like the one fixed in commit c361016a in
the future.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: James Morris <james.l.morris@oracle.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Now that the xattr handler is passed to the xattr handler operations, we
have access to the attribute name prefix, so simplify the squashfs xattr
handlers a bit.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Phillip Lougher <phillip@squashfs.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The xattr_handler operations are currently all passed a file system
specific flags value which the operations can use to disambiguate between
different handlers; some file systems use that to distinguish the xattr
namespace, for example. In some oprations, it would be useful to also have
access to the handler prefix. To allow that, pass a pointer to the handler
to operations instead of the flags value alone.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
list_entry is just a wrapper for container_of, but it is arguably
wrong (and slightly confusing) to use it when the pointed-to struct
member is not a struct list_head. Use container_of directly instead.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
that's the bulk of filesystem drivers dealing with inodes of their own
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Add support for reading file systems compressed with the
LZ4 compression algorithm.
This patch adds the LZ4 decompressor wrapper code.
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Direct decompression into the page cache. If we fall back
to using an intermediate buffer (because we cannot grab all the
page cache pages) and we get a decompress fail, we forgot to
release the pages.
Reported-by: Roman Peniaev <r.peniaev@gmail.com>
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
This introduces an implementation of squashfs_readpage_block()
that directly decompresses into the page cache.
This uses the previously added page handler abstraction to push
down the necessary kmap_atomic/kunmap_atomic operations on the
page cache buffers into the decompressors. This enables
direct copying into the page cache without using the slow
kmap/kunmap calls.
The code detects when multiple threads are racing in
squashfs_readpage() to decompress the same block, and avoids
this regression by falling back to using an intermediate
buffer.
This patch enhances the performance of Squashfs significantly
when multiple processes are accessing the filesystem simultaneously
because it not only reduces memcopying, but it more importantly
eliminates the lock contention on the intermediate buffer.
Using single-thread decompression.
dd if=file1 of=/dev/null bs=4096 &
dd if=file2 of=/dev/null bs=4096 &
dd if=file3 of=/dev/null bs=4096 &
dd if=file4 of=/dev/null bs=4096
Before:
629145600 bytes (629 MB) copied, 45.8046 s, 13.7 MB/s
After:
629145600 bytes (629 MB) copied, 9.29414 s, 67.7 MB/s
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Restructure squashfs_readpage() splitting it into separate
functions for datablocks, fragments and sparse blocks.
Move the memcpying (from squashfs cache entry) implementation of
squashfs_readpage_block into file_cache.c
This allows different implementations to be supported.
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Further generalise the decompressors by adding a page handler
abstraction. This adds helpers to allow the decompressors
to access and process the output buffers in an implementation
independant manner.
This allows different types of output buffer to be passed
to the decompressors, with the implementation specific
aspects handled at decompression time, but without the
knowledge being held in the decompressor wrapper code.
This will allow the decompressors to handle Squashfs
cache buffers, and page cache pages.
This patch adds the abstraction and an implementation for
the caches.
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Add a multi-threaded decompression implementation which uses
percpu variables.
Using percpu variables has advantages and disadvantages over
implementations which do not use percpu variables.
Advantages:
* the nature of percpu variables ensures decompression is
load-balanced across the multiple cores.
* simplicity.
Disadvantages: it limits decompression to one thread per core.
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Now squashfs have used for only one stream buffer for decompression
so it hurts parallel read performance so this patch supports
multiple decompressor to enhance performance parallel I/O.
Four 1G file dd read on KVM machine which has 2 CPU and 4G memory.
dd if=test/test1.dat of=/dev/null &
dd if=test/test2.dat of=/dev/null &
dd if=test/test3.dat of=/dev/null &
dd if=test/test4.dat of=/dev/null &
old : 1m39s -> new : 9s
* From v1
* Change comp_strm with decomp_strm - Phillip
* Change/add comments - Phillip
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
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: Phillip Lougher <phillip@squashfs.org.uk>
Reviewed-by: Minchan Kim <minchan@kernel.org>
