linux-stable.git/include/linux/fs.h, branch linux-2.6.33.y

mm: prevent concurrent unmap_mapping_range() on the same inode

2011-07-13T03:31:27+00:00

commit 2aa15890f3c191326678f1bd68af61ec6b8753ec upstream.

Michael Leun reported that running parallel opens on a fuse filesystem
can trigger a "kernel BUG at mm/truncate.c:475"

Gurudas Pai reported the same bug on NFS.

The reason is, unmap_mapping_range() is not prepared for more than
one concurrent invocation per inode.  For example:

  thread1: going through a big range, stops in the middle of a vma and
     stores the restart address in vm_truncate_count.

  thread2: comes in with a small (e.g. single page) unmap request on
     the same vma, somewhere before restart_address, finds that the
     vma was already unmapped up to the restart address and happily
     returns without doing anything.

Another scenario would be two big unmap requests, both having to
restart the unmapping and each one setting vm_truncate_count to its
own value.  This could go on forever without any of them being able to
finish.

Truncate and hole punching already serialize with i_mutex.  Other
callers of unmap_mapping_range() do not, and it's difficult to get
i_mutex protection for all callers.  In particular ->d_revalidate(),
which calls invalidate_inode_pages2_range() in fuse, may be called
with or without i_mutex.

This patch adds a new mutex to 'struct address_space' to prevent
running multiple concurrent unmap_mapping_range() on the same mapping.

[ We'll hopefully get rid of all this with the upcoming mm
  preemptibility series by Peter Zijlstra, the "mm: Remove i_mmap_mutex
  lockbreak" patch in particular.  But that is for 2.6.39 ]

Signed-off-by: Miklos Szeredi 
Reported-by: Michael Leun 
Reported-by: Gurudas Pai 
Tested-by: Gurudas Pai 
Acked-by: Hugh Dickins 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

vfs: add NOFOLLOW flag to umount(2)

2010-07-05T18:16:09+00:00

commit db1f05bb85d7966b9176e293f3ceead1cb8b5d79 upstream.

Add a new UMOUNT_NOFOLLOW flag to umount(2).  This is needed to prevent
symlink attacks in unprivileged unmounts (fuse, samba, ncpfs).

Additionally, return -EINVAL if an unknown flag is used (and specify
an explicitly unused flag: UMOUNT_UNUSED).  This makes it possible for
the caller to determine if a flag is supported or not.

CC: Eugene Teo 
CC: Michael Kerrisk 
Signed-off-by: Miklos Szeredi 
Signed-off-by: Al Viro 
Signed-off-by: Greg Kroah-Hartman

wrong type for 'magic' argument in simple_fill_super()

2010-07-05T18:16:06+00:00

commit 7d683a09990ff095a91b6e724ecee0ff8733274a upstream.

It's used to superblock ->s_magic, which is unsigned long.

Signed-off-by: Roberto Sassu 
Reviewed-by: Mimi Zohar 
Signed-off-by: Eric Paris 
Signed-off-by: Al Viro 
Signed-off-by: Greg Kroah-Hartman

raw: fsync method is now required

2010-04-26T14:47:49+00:00

commit 55ab3a1ff843e3f0e24d2da44e71bffa5d853010 upstream.

Commit 148f948ba877f4d3cdef036b1ff6d9f68986706a (vfs: Introduce new
helpers for syncing after writing to O_SYNC file or IS_SYNC inode) broke
the raw driver.

We now call through generic_file_aio_write -> generic_write_sync ->
vfs_fsync_range.  vfs_fsync_range has:

        if (!fop || !fop->fsync) {
                ret = -EINVAL;
                goto out;
        }

But drivers/char/raw.c doesn't set an fsync method.

We have two options: fix it or remove the raw driver completely.  I'm
happy to do either, the fact this has been broken for so long suggests it
is rarely used.

The patch below adds an fsync method to the raw driver.  My knowledge of
the block layer is pretty sketchy so this could do with a once over.

If we instead decide to remove the raw driver, this patch might still be
useful as a backport to 2.6.33 and 2.6.32.

Signed-off-by: Anton Blanchard 
Reviewed-by: Jan Kara 
Cc: Christoph Hellwig 
Cc: Alexander Viro 
Cc: Jens Axboe 
Reviewed-by: Jeff Moyer 
Tested-by: Jeff Moyer 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

readahead: introduce FMODE_RANDOM for POSIX_FADV_RANDOM

2010-03-15T16:05:54+00:00

commit 0141450f66c3c12a3aaa869748caa64241885cdf upstream.

This fixes inefficient page-by-page reads on POSIX_FADV_RANDOM.

POSIX_FADV_RANDOM used to set ra_pages=0, which leads to poor performance:
a 16K read will be carried out in 4 _sync_ 1-page reads.

In other places, ra_pages==0 means
- it's ramfs/tmpfs/hugetlbfs/sysfs/configfs
- some IO error happened
where multi-page read IO won't help or should be avoided.

POSIX_FADV_RANDOM actually want a different semantics: to disable the
*heuristic* readahead algorithm, and to use a dumb one which faithfully
submit read IO for whatever application requests.

So introduce a flag FMODE_RANDOM for POSIX_FADV_RANDOM.

Note that the random hint is not likely to help random reads performance
noticeably.  And it may be too permissive on huge request size (its IO
size is not limited by read_ahead_kb).

In Quentin's report (http://lkml.org/lkml/2009/12/24/145), the overall
(NFS read) performance of the application increased by 313%!

Tested-by: Quentin Barnes 
Signed-off-by: Wu Fengguang 
Cc: Nick Piggin 
Cc: Andi Kleen 
Cc: Steven Whitehouse 
Cc: David Howells 
Cc: Jonathan Corbet 
Cc: Al Viro 
Cc: Christoph Hellwig 
Cc: Trond Myklebust 
Cc: Chuck Lever 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

fs: inode - remove 8 bytes of padding on 64bits allowing 1 more objects/slab under slub

2010-02-19T15:41:13+00:00

This removes 8 bytes of padding from struct inode on 64bit builds, and
so allows 1 more object/slab in the inode_cache when using slub.

Signed-off-by: Richard Kennedy 
----
patch against 2.6.33-rc8
compiled & tested on x86_64 AMDX2

I've been running this patch for over a week with no obvious problems
regards
Richard
Signed-off-by: Al Viro

Fix ACC_MODE() for real

2010-01-14T14:05:26+00:00

commit 5300990c0370e804e49d9a59d928c5d53fb73487 had stepped on a rather
nasty mess: definitions of ACC_MODE used to be different.  Fixed the
resulting breakage, converting them to variant that takes O_... value;
all callers have that and it actually simplifies life (see tomoyo part
of changes).

Signed-off-by: Al Viro

Add unlocked version of inode_add_bytes() function

2009-12-23T12:33:54+00:00

Quota code requires unlocked version of this function. Off course
we can just copy-paste the code, but copy-pasting is always an evil.

Signed-off-by: Dmitry Monakhov 
Signed-off-by: Jan Kara

Remove obsolete comment in fs.h

2009-12-22T17:27:35+00:00

This question was determined to be a bug which was fixed in
commit 4a3b0a49.

Signed-off-by: Andreas Gruenbacher 
Cc: Jan Blunck 
Signed-off-by: Al Viro

Sanitize f_flags helpers

2009-12-22T17:27:34+00:00

* pull ACC_MODE to fs.h; we have several copies all over the place
* nightmarish expression calculating f_mode by f_flags deserves a helper
too (OPEN_FMODE(flags))

Signed-off-by: Al Viro