linux-stable.git/fs/gfs2, branch linux-3.12.y

gfs2: avoid uninitialized variable warning

2017-05-09T06:19:45+00:00

commit 67893f12e5374bbcaaffbc6e570acbc2714ea884 upstream.

We get a bogus warning about a potential uninitialized variable
use in gfs2, because the compiler does not figure out that we
never use the leaf number if get_leaf_nr() returns an error:

fs/gfs2/dir.c: In function 'get_first_leaf':
fs/gfs2/dir.c:802:9: warning: 'leaf_no' may be used uninitialized in this function [-Wmaybe-uninitialized]
fs/gfs2/dir.c: In function 'dir_split_leaf':
fs/gfs2/dir.c:1021:8: warning: 'leaf_no' may be used uninitialized in this function [-Wmaybe-uninitialized]

Changing the 'if (!error)' to 'if (!IS_ERR_VALUE(error))' is
sufficient to let gcc understand that this is exactly the same
condition as in IS_ERR() so it can optimize the code path enough
to understand it.

Signed-off-by: Arnd Bergmann 
Signed-off-by: Bob Peterson 
Signed-off-by: Jiri Slaby

posix_acl: Clear SGID bit when setting file permissions

2017-01-27T10:15:59+00:00

commit 073931017b49d9458aa351605b43a7e34598caef upstream.

When file permissions are modified via chmod(2) and the user is not in
the owning group or capable of CAP_FSETID, the setgid bit is cleared in
inode_change_ok().  Setting a POSIX ACL via setxattr(2) sets the file
permissions as well as the new ACL, but doesn't clear the setgid bit in
a similar way; this allows to bypass the check in chmod(2).  Fix that.

Reviewed-by: Christoph Hellwig 
Reviewed-by: Jeff Layton 
Signed-off-by: Jan Kara 
Signed-off-by: Andreas Gruenbacher 
Signed-off-by: Jiri Slaby

mm: non-atomically mark page accessed during page cache allocation where possible

2014-09-26T09:52:05+00:00

commit 2457aec63745e235bcafb7ef312b182d8682f0fc upstream.

aops->write_begin may allocate a new page and make it visible only to have
mark_page_accessed called almost immediately after.  Once the page is
visible the atomic operations are necessary which is noticable overhead
when writing to an in-memory filesystem like tmpfs but should also be
noticable with fast storage.  The objective of the patch is to initialse
the accessed information with non-atomic operations before the page is
visible.

The bulk of filesystems directly or indirectly use
grab_cache_page_write_begin or find_or_create_page for the initial
allocation of a page cache page.  This patch adds an init_page_accessed()
helper which behaves like the first call to mark_page_accessed() but may
called before the page is visible and can be done non-atomically.

The primary APIs of concern in this care are the following and are used
by most filesystems.

	find_get_page
	find_lock_page
	find_or_create_page
	grab_cache_page_nowait
	grab_cache_page_write_begin

All of them are very similar in detail to the patch creates a core helper
pagecache_get_page() which takes a flags parameter that affects its
behavior such as whether the page should be marked accessed or not.  Then
old API is preserved but is basically a thin wrapper around this core
function.

Each of the filesystems are then updated to avoid calling
mark_page_accessed when it is known that the VM interfaces have already
done the job.  There is a slight snag in that the timing of the
mark_page_accessed() has now changed so in rare cases it's possible a page
gets to the end of the LRU as PageReferenced where as previously it might
have been repromoted.  This is expected to be rare but it's worth the
filesystem people thinking about it in case they see a problem with the
timing change.  It is also the case that some filesystems may be marking
pages accessed that previously did not but it makes sense that filesystems
have consistent behaviour in this regard.

The test case used to evaulate this is a simple dd of a large file done
multiple times with the file deleted on each iterations.  The size of the
file is 1/10th physical memory to avoid dirty page balancing.  In the
async case it will be possible that the workload completes without even
hitting the disk and will have variable results but highlight the impact
of mark_page_accessed for async IO.  The sync results are expected to be
more stable.  The exception is tmpfs where the normal case is for the "IO"
to not hit the disk.

The test machine was single socket and UMA to avoid any scheduling or NUMA
artifacts.  Throughput and wall times are presented for sync IO, only wall
times are shown for async as the granularity reported by dd and the
variability is unsuitable for comparison.  As async results were variable
do to writback timings, I'm only reporting the maximum figures.  The sync
results were stable enough to make the mean and stddev uninteresting.

The performance results are reported based on a run with no profiling.
Profile data is based on a separate run with oprofile running.

async dd
                                    3.15.0-rc3            3.15.0-rc3
                                       vanilla           accessed-v2
ext3    Max      elapsed     13.9900 (  0.00%)     11.5900 ( 17.16%)
tmpfs	Max      elapsed      0.5100 (  0.00%)      0.4900 (  3.92%)
btrfs   Max      elapsed     12.8100 (  0.00%)     12.7800 (  0.23%)
ext4	Max      elapsed     18.6000 (  0.00%)     13.3400 ( 28.28%)
xfs	Max      elapsed     12.5600 (  0.00%)      2.0900 ( 83.36%)

The XFS figure is a bit strange as it managed to avoid a worst case by
sheer luck but the average figures looked reasonable.

        samples percentage
ext3       86107    0.9783  vmlinux-3.15.0-rc4-vanilla        mark_page_accessed
ext3       23833    0.2710  vmlinux-3.15.0-rc4-accessed-v3r25 mark_page_accessed
ext3        5036    0.0573  vmlinux-3.15.0-rc4-accessed-v3r25 init_page_accessed
ext4       64566    0.8961  vmlinux-3.15.0-rc4-vanilla        mark_page_accessed
ext4        5322    0.0713  vmlinux-3.15.0-rc4-accessed-v3r25 mark_page_accessed
ext4        2869    0.0384  vmlinux-3.15.0-rc4-accessed-v3r25 init_page_accessed
xfs        62126    1.7675  vmlinux-3.15.0-rc4-vanilla        mark_page_accessed
xfs         1904    0.0554  vmlinux-3.15.0-rc4-accessed-v3r25 init_page_accessed
xfs          103    0.0030  vmlinux-3.15.0-rc4-accessed-v3r25 mark_page_accessed
btrfs      10655    0.1338  vmlinux-3.15.0-rc4-vanilla        mark_page_accessed
btrfs       2020    0.0273  vmlinux-3.15.0-rc4-accessed-v3r25 init_page_accessed
btrfs        587    0.0079  vmlinux-3.15.0-rc4-accessed-v3r25 mark_page_accessed
tmpfs      59562    3.2628  vmlinux-3.15.0-rc4-vanilla        mark_page_accessed
tmpfs       1210    0.0696  vmlinux-3.15.0-rc4-accessed-v3r25 init_page_accessed
tmpfs         94    0.0054  vmlinux-3.15.0-rc4-accessed-v3r25 mark_page_accessed

[akpm@linux-foundation.org: don't run init_page_accessed() against an uninitialised pointer]
Signed-off-by: Mel Gorman 
Cc: Johannes Weiner 
Cc: Vlastimil Babka 
Cc: Jan Kara 
Cc: Michal Hocko 
Cc: Hugh Dickins 
Cc: Dave Hansen 
Cc: Theodore Ts'o 
Cc: "Paul E. McKenney" 
Cc: Oleg Nesterov 
Cc: Rik van Riel 
Cc: Peter Zijlstra 
Tested-by: Prabhakar Lad 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Mel Gorman 
Signed-off-by: Jiri Slaby

GFS2: revert "GFS2: d_splice_alias() can't return error"

2014-06-27T08:25:10+00:00

commit d57b9c9a999a8f4475fe73fba629c964245800ca upstream.

0d0d110720d7960b77c03c9f2597faaff4b484ae asserts that "d_splice_alias()
can't return error unless it was given an IS_ERR(inode)".

That was true of the implementation of d_splice_alias, but this is
really a problem with d_splice_alias: at a minimum it should be able to
return -ELOOP in the case where inserting the given dentry would cause a
directory loop.

Signed-off-by: J. Bruce Fields 
Signed-off-by: Steven Whitehouse 

Signed-off-by: Jiri Slaby

GFS2: Increase i_writecount during gfs2_setattr_chown

2014-01-25T16:49:28+00:00

commit 62e96cf81988101fe9e086b2877307b6adda5197 upstream.

This patch calls get_write_access in function gfs2_setattr_chown,
which merely increases inode->i_writecount for the duration of the
function. That will ensure that any file closes won't delete the
inode's multi-block reservation while the function is running.
It also ensures that a multi-block reservation exists when needed
for quota change operations during the chown.

Signed-off-by: Bob Peterson 
Signed-off-by: Steven Whitehouse 
Signed-off-by: Greg Kroah-Hartman

GFS2: Fix incorrect invalidation for DIO/buffered I/O

2014-01-09T20:25:15+00:00

commit dfd11184d894cd0a92397b25cac18831a1a6a5bc upstream.

In patch 209806aba9d540dde3db0a5ce72307f85f33468f we allowed
local deferred locks to be granted against a cached exclusive
lock. That opened up a corner case which this patch now
fixes.

The solution to the problem is to check whether we have cached
pages each time we do direct I/O and if so to unmap, flush
and invalidate those pages. Since the glock state machine
normally does that for us, mostly the code will be a no-op.

Signed-off-by: Steven Whitehouse 
Signed-off-by: Greg Kroah-Hartman

GFS2: Fix slab memory leak in gfs2_bufdata

2014-01-09T20:25:15+00:00

commit 502be2a32f09f388e4ff34ef2e3ebcabbbb261da upstream.

This patch fixes a slab memory leak that sometimes can occur
for files with a very short lifespan. The problem occurs when
a dinode is deleted before it has gotten to the journal properly.
In the leak scenario, the bd object is pinned for journal
committment (queued to the metadata buffers queue: sd_log_le_buf)
but is subsequently unpinned and dequeued before it finds its way
to the ail or the revoke queue. In this rare circumstance, the bd
object needs to be freed from slab memory, or it is forgotten.
We have to be very careful how we do it, though, because
multiple processes can call gfs2_remove_from_journal. In order to
avoid double-frees, only the process that does the unpinning is
allowed to free the bd.

Signed-off-by: Bob Peterson 
Signed-off-by: Steven Whitehouse 
Signed-off-by: Greg Kroah-Hartman

GFS2: Fix use-after-free race when calling gfs2_remove_from_ail

2014-01-09T20:25:15+00:00

commit 9290a9a7c0bcf5400e8dbfbf9707fa68ea3fb338 upstream.

Function gfs2_remove_from_ail drops the reference on the bh via
brelse. This patch fixes a race condition whereby bh is deferenced
after the brelse when setting bd->bd_blkno = bh->b_blocknr;
Under certain rare circumstances, bh might be gone or reused,
and bd->bd_blkno is set to whatever that memory happens to be,
which is often 0. Later, in gfs2_trans_add_unrevoke, that bd fails
the test "bd->bd_blkno >= blkno" which causes it to never be freed.
The end result is that the bd is never freed from the bufdata cache,
which results in this error:
slab error in kmem_cache_destroy(): cache `gfs2_bufdata': Can't free all objects

Signed-off-by: Bob Peterson 
Signed-off-by: Steven Whitehouse 
Signed-off-by: Greg Kroah-Hartman

GFS2: don't hold s_umount over blkdev_put

2014-01-09T20:25:14+00:00

commit dfe5b9ad83a63180f358b27d1018649a27b394a9 upstream.

This is a GFS2 version of Tejun's patch:
4f331f01b9c43bf001d3ffee578a97a1e0633eac
vfs: don't hold s_umount over close_bdev_exclusive() call

In this case its blkdev_put itself that is the issue and this
patch uses the same solution of dropping and retaking s_umount.

Reported-by: Tejun Heo 
Reported-by: Al Viro 
Signed-off-by: Steven Whitehouse 
Signed-off-by: Greg Kroah-Hartman

GFS2: Fix ref count bug relating to atomic_open

2013-12-04T19:06:16+00:00

commit ea0341e071527d5cec350917b01ab901af09d758 upstream.

In the case that atomic_open calls finish_no_open() with
the dentry that was supplied to gfs2_atomic_open() an
extra reference count is required. This patch fixes that
issue preventing a bug trap triggering at umount time.

Signed-off-by: Steven Whitehouse 
Signed-off-by: Greg Kroah-Hartman