05 Sep, 2018
2 commits
-
[ Upstream commit a3f94cb99a854fa381fe7fadd97c4f61633717a5 ]
Previously in squashfs_readpage() when copying data into the page
cache, it used the length of the datablock read from the filesystem
(after decompression). However, if the filesystem has been corrupted
this data block may be short, which will leave pages unfilled.The fix for this is to compute the expected number of bytes to copy
from the inode size, and use this to detect if the block is short.Signed-off-by: Phillip Lougher
Tested-by: Willy Tarreau
Cc: Анатолий Тросиненко
Signed-off-by: Linus Torvalds
Signed-off-by: Sasha Levin
Signed-off-by: Greg Kroah-Hartman -
[ Upstream commit cdbb65c4c7ead680ebe54f4f0d486e2847a500ea ]
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
Tested-by: Willy Tarreau
Cc: Al Viro
Cc: Phillip Lougher
Signed-off-by: Linus Torvalds
Signed-off-by: Sasha Levin
Signed-off-by: Greg Kroah-Hartman
06 Aug, 2018
2 commits
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commit 71755ee5350b63fb1f283de8561cdb61b47f4d1d 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
Acked-by:: Phillip Lougher ,
Cc: Willy Tarreau
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman -
commit d512584780d3e6a7cacb2f482834849453d444a1 upstream.
Anatoly reports another squashfs fuzzing issue, where the decompression
parameters themselves are in a compressed block.This causes squashfs_read_data() to be called in order to read the
decompression options before the decompression stream having been set
up, making squashfs go sideways.Reported-by: Anatoly Trosinenko
Acked-by: Phillip Lougher
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman
03 Aug, 2018
1 commit
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commit 01cfb7937a9af2abb1136c7e89fbf3fd92952956 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
Cc: Al Viro
Cc: Phillip Lougher
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman
02 Nov, 2017
1 commit
-
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.By default all files without license information are under the default
license of the kernel, which is GPL version 2.Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if
Reviewed-by: Philippe Ombredanne
Reviewed-by: Thomas Gleixner
Signed-off-by: Greg Kroah-Hartman
09 Sep, 2017
1 commit
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Add zstd compression and decompression support to SquashFS. zstd is a
great fit for SquashFS because it can compress at ratios approaching xz,
while decompressing twice as fast as zlib. For SquashFS in particular,
it can decompress as fast as lzo and lz4. It also has the flexibility
to turn down the compression ratio for faster compression times.The compression benchmark is run on the file tree from the SquashFS archive
found in ubuntu-16.10-desktop-amd64.iso [1]. It uses `mksquashfs` with the
default block size (128 KB) and and various compression algorithms/levels.
xz and zstd are also benchmarked with 256 KB blocks. The decompression
benchmark times how long it takes to `tar` the file tree into `/dev/null`.
See the benchmark file in the upstream zstd source repository located under
`contrib/linux-kernel/squashfs-benchmark.sh` [2] for details.I ran the benchmarks on a Ubuntu 14.04 VM with 2 cores and 4 GiB of RAM.
The VM is running on a MacBook Pro with a 3.1 GHz Intel Core i7 processor,
16 GB of RAM, and a SSD.| Method | Ratio | Compression MB/s | Decompression MB/s |
|----------------|-------|------------------|--------------------|
| gzip | 2.92 | 15 | 128 |
| lzo | 2.64 | 9.5 | 217 |
| lz4 | 2.12 | 94 | 218 |
| xz | 3.43 | 5.5 | 35 |
| xz 256 KB | 3.53 | 5.4 | 40 |
| zstd 1 | 2.71 | 96 | 210 |
| zstd 5 | 2.93 | 69 | 198 |
| zstd 10 | 3.01 | 41 | 225 |
| zstd 15 | 3.13 | 11.4 | 224 |
| zstd 16 256 KB | 3.24 | 8.1 | 210 |This patch was written by Sean Purcell , but I will be
taking over the submission process.[1] http://releases.ubuntu.com/16.10/
[2] https://github.com/facebook/zstd/blob/dev/contrib/linux-kernel/squashfs-benchmark.shzstd source repository: https://github.com/facebook/zstd
Signed-off-by: Sean Purcell
Signed-off-by: Nick Terrell
Signed-off-by: Chris Mason
Acked-by: Phillip Lougher
25 Feb, 2017
1 commit
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Update fs/pstore and fs/squashfs to use the updated functions from the
new LZ4 module.Link: http://lkml.kernel.org/r/1486321748-19085-5-git-send-email-4sschmid@informatik.uni-hamburg.de
Signed-off-by: Sven Schmidt
Cc: Bongkyu Kim
Cc: Rui Salvaterra
Cc: Sergey Senozhatsky
Cc: Greg Kroah-Hartman
Cc: Herbert Xu
Cc: David S. Miller
Cc: Anton Vorontsov
Cc: Colin Cross
Cc: Kees Cook
Cc: Tony Luck
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
18 Dec, 2016
1 commit
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…/linux/kernel/git/mszeredi/vfs
Pull partial readlink cleanups from Miklos Szeredi.
This is the uncontroversial part of the readlink cleanup patch-set that
simplifies the default readlink handling.Miklos and Al are still discussing the rest of the series.
* git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
vfs: make generic_readlink() static
vfs: remove ".readlink = generic_readlink" assignments
vfs: default to generic_readlink()
vfs: replace calling i_op->readlink with vfs_readlink()
proc/self: use generic_readlink
ecryptfs: use vfs_get_link()
bad_inode: add missing i_op initializers
09 Dec, 2016
1 commit
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If .readlink == NULL implies generic_readlink().
Generated by:
to_del="\.readlink.*=.*generic_readlink"
for i in `git grep -l $to_del`; do sed -i "/$to_del"/d $i; doneSigned-off-by: Miklos Szeredi
01 Nov, 2016
1 commit
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Nothing in fs.h should require blk_types.h to be included.
Signed-off-by: Christoph Hellwig
Signed-off-by: Jens Axboe
08 Oct, 2016
1 commit
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These inode operations are no longer used; remove them.
Signed-off-by: Andreas Gruenbacher
Signed-off-by: Al Viro
08 Jun, 2016
1 commit
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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
Reviewed-by: Christoph Hellwig
Reviewed-by: Hannes Reinecke
Signed-off-by: Jens Axboe
09 May, 2016
1 commit
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don't need to lock directory in ->llseek(), either
Signed-off-by: Al Viro
03 May, 2016
1 commit
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The rest of work.xattr stuff isn't needed for this branch
11 Apr, 2016
1 commit
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... and do not assume they are already attached to each other
Signed-off-by: Al Viro
05 Apr, 2016
2 commits
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Mostly direct substitution with occasional adjustment or removing
outdated comments.Signed-off-by: Kirill A. Shutemov
Acked-by: Michal Hocko
Signed-off-by: Linus Torvalds -
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:
- << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> ;
- >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> ;
- 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
Acked-by: Michal Hocko
Signed-off-by: Linus Torvalds
15 Jan, 2016
1 commit
-
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
Acked-by: Johannes Weiner
Acked-by: Michal Hocko
Cc: Tejun Heo
Cc: Greg Thelen
Cc: Christoph Lameter
Cc: Pekka Enberg
Cc: David Rientjes
Cc: Joonsoo Kim
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
13 Jan, 2016
1 commit
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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()
...
12 Jan, 2016
1 commit
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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
07 Jan, 2016
1 commit
-
Signed-off-by: Dmitry Monakhov
Signed-off-by: Al Viro
31 Dec, 2015
1 commit
-
Signed-off-by: Al Viro
14 Dec, 2015
1 commit
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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
Signed-off-by: Al Viro
09 Dec, 2015
2 commits
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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
-
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
07 Dec, 2015
1 commit
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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
Reviewed-by: James Morris
Signed-off-by: Al Viro
14 Nov, 2015
2 commits
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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
Cc: Phillip Lougher
Signed-off-by: Al Viro -
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
Reviewed-by: Christoph Hellwig
Signed-off-by: Al Viro
24 Jun, 2015
1 commit
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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
Signed-off-by: Al Viro
16 Apr, 2015
1 commit
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that's the bulk of filesystem drivers dealing with inodes of their own
Signed-off-by: David Howells
Signed-off-by: Al Viro
28 Nov, 2014
1 commit
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Add the glue code, and also update the documentation.
Signed-off-by: Phillip Lougher
27 Nov, 2014
1 commit
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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
07 Aug, 2014
2 commits
-
- Convert printk to pr_foo()
- Add pr_fmt for future logging entries
- Coalesce formatsSigned-off-by: Fabian Frederick
Cc: Phillip Lougher
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
kmalloc_array() manages count*sizeof overflow.
Signed-off-by: Fabian Frederick
Cc: Phillip Lougher
Cc: Joe Perches
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
05 Jun, 2014
1 commit
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Update the last pr_warning callsite in fs branch
Signed-off-by: Fabian Frederick
Cc: Phillip Lougher
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
13 Mar, 2014
1 commit
-
Previously, the no-op "mount -o mount /dev/xxx" operation when the
file system is already mounted read-write causes an implied,
unconditional syncfs(). This seems pretty stupid, and it's certainly
documented or guaraunteed to do this, nor is it particularly useful,
except in the case where the file system was mounted rw and is getting
remounted read-only.However, it's possible that there might be some file systems that are
actually depending on this behavior. In most file systems, it's
probably fine to only call sync_filesystem() when transitioning from
read-write to read-only, and there are some file systems where this is
not needed at all (for example, for a pseudo-filesystem or something
like romfs).Signed-off-by: "Theodore Ts'o"
Cc: linux-fsdevel@vger.kernel.org
Cc: Christoph Hellwig
Cc: Artem Bityutskiy
Cc: Adrian Hunter
Cc: Evgeniy Dushistov
Cc: Jan Kara
Cc: OGAWA Hirofumi
Cc: Anders Larsen
Cc: Phillip Lougher
Cc: Kees Cook
Cc: Mikulas Patocka
Cc: Petr Vandrovec
Cc: xfs@oss.sgi.com
Cc: linux-btrfs@vger.kernel.org
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Cc: codalist@coda.cs.cmu.edu
Cc: linux-ext4@vger.kernel.org
Cc: linux-f2fs-devel@lists.sourceforge.net
Cc: fuse-devel@lists.sourceforge.net
Cc: cluster-devel@redhat.com
Cc: linux-mtd@lists.infradead.org
Cc: jfs-discussion@lists.sourceforge.net
Cc: linux-nfs@vger.kernel.org
Cc: linux-nilfs@vger.kernel.org
Cc: linux-ntfs-dev@lists.sourceforge.net
Cc: ocfs2-devel@oss.oracle.com
Cc: reiserfs-devel@vger.kernel.org
24 Nov, 2013
1 commit
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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
Signed-off-by: Phillip Lougher
20 Nov, 2013
2 commits
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Fix static checker complaint that stream is not checked in
squashfs_decompressor_destroy().Reported-by: Dan Carpenter
Signed-off-by: Phillip Lougher
Reviewed-by: Minchan Kim -
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=4096Before:
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
Reviewed-by: Minchan Kim