linux-toradex.git/fs, branch v4.4.3 Linux kernel for Apalis and Colibri modules timerfd: Handle relative timers with CONFIG_TIME_LOW_RES proper 2016-02-25T20:01:25+00:00 Thomas Gleixner tglx@linutronix.de 2016-01-14T16:54:46+00:00 565f222968d300657ad40d2fad91e4ccf3148d89 commit b62526ed11a1fe3861ab98d40b7fdab8981d788a upstream. Helge reported that a relative timer can return a remaining time larger than the programmed relative time on parisc and other architectures which have CONFIG_TIME_LOW_RES set. This happens because we add a jiffie to the resulting expiry time to prevent short timeouts. Use the new function hrtimer_expires_remaining_adjusted() to calculate the remaining time. It takes that extra added time into account for relative timers. Reported-and-tested-by: Helge Deller <deller@gmx.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: John Stultz <john.stultz@linaro.org> Cc: linux-m68k@lists.linux-m68k.org Cc: dhowells@redhat.com Link: http://lkml.kernel.org/r/20160114164159.354500742@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit b62526ed11a1fe3861ab98d40b7fdab8981d788a upstream.

Helge reported that a relative timer can return a remaining time larger than
the programmed relative time on parisc and other architectures which have
CONFIG_TIME_LOW_RES set. This happens because we add a jiffie to the resulting
expiry time to prevent short timeouts.

Use the new function hrtimer_expires_remaining_adjusted() to calculate the
remaining time. It takes that extra added time into account for relative
timers.

Reported-and-tested-by: Helge Deller <deller@gmx.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: linux-m68k@lists.linux-m68k.org
Cc: dhowells@redhat.com
Link: http://lkml.kernel.org/r/20160114164159.354500742@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
xfs: log mount failures don't wait for buffers to be released 2016-02-25T20:01:24+00:00 Dave Chinner dchinner@redhat.com 2016-01-18T21:28:10+00:00 f86701c4f3cd59bac9363846e62fd26ecb2437c2 commit 85bec5460ad8e05e0a8d70fb0f6750eb719ad092 upstream. Recently I've been seeing xfs/051 fail on 1k block size filesystems. Trying to trace the events during the test lead to the problem going away, indicating that it was a race condition that lead to this ASSERT failure: XFS: Assertion failed: atomic_read(&pag->pag_ref) == 0, file: fs/xfs/xfs_mount.c, line: 156 ..... [<ffffffff814e1257>] xfs_free_perag+0x87/0xb0 [<ffffffff814e21b9>] xfs_mountfs+0x4d9/0x900 [<ffffffff814e5dff>] xfs_fs_fill_super+0x3bf/0x4d0 [<ffffffff811d8800>] mount_bdev+0x180/0x1b0 [<ffffffff814e3ff5>] xfs_fs_mount+0x15/0x20 [<ffffffff811d90a8>] mount_fs+0x38/0x170 [<ffffffff811f4347>] vfs_kern_mount+0x67/0x120 [<ffffffff811f7018>] do_mount+0x218/0xd60 [<ffffffff811f7e5b>] SyS_mount+0x8b/0xd0 When I finally caught it with tracing enabled, I saw that AG 2 had an elevated reference count and a buffer was responsible for it. I tracked down the specific buffer, and found that it was missing the final reference count release that would put it back on the LRU and hence be found by xfs_wait_buftarg() calls in the log mount failure handling. The last four traces for the buffer before the assert were (trimmed for relevance) kworker/0:1-5259 xfs_buf_iodone: hold 2 lock 0 flags ASYNC kworker/0:1-5259 xfs_buf_ioerror: hold 2 lock 0 error -5 mount-7163 xfs_buf_lock_done: hold 2 lock 0 flags ASYNC mount-7163 xfs_buf_unlock: hold 2 lock 1 flags ASYNC This is an async write that is completing, so there's nobody waiting for it directly. Hence we call xfs_buf_relse() once all the processing is complete. That does: static inline void xfs_buf_relse(xfs_buf_t *bp) { xfs_buf_unlock(bp); xfs_buf_rele(bp); } Now, it's clear that mount is waiting on the buffer lock, and that it has been released by xfs_buf_relse() and gained by mount. This is expected, because at this point the mount process is in xfs_buf_delwri_submit() waiting for all the IO it submitted to complete. The mount process, however, is waiting on the lock for the buffer because it is in xfs_buf_delwri_submit(). This waits for IO completion, but it doesn't wait for the buffer reference owned by the IO to go away. The mount process collects all the completions, fails the log recovery, and the higher level code then calls xfs_wait_buftarg() to free all the remaining buffers in the filesystem. The issue is that on unlocking the buffer, the scheduler has decided that the mount process has higher priority than the the kworker thread that is running the IO completion, and so immediately switched contexts to the mount process from the semaphore unlock code, hence preventing the kworker thread from finishing the IO completion and releasing the IO reference to the buffer. Hence by the time that xfs_wait_buftarg() is run, the buffer still has an active reference and so isn't on the LRU list that the function walks to free the remaining buffers. Hence we miss that buffer and continue onwards to tear down the mount structures, at which time we get find a stray reference count on the perag structure. On a non-debug kernel, this will be ignored and the structure torn down and freed. Hence when the kworker thread is then rescheduled and the buffer released and freed, it will access a freed perag structure. The problem here is that when the log mount fails, we still need to quiesce the log to ensure that the IO workqueues have returned to idle before we run xfs_wait_buftarg(). By synchronising the workqueues, we ensure that all IO completions are fully processed, not just to the point where buffers have been unlocked. This ensures we don't end up in the situation above. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 85bec5460ad8e05e0a8d70fb0f6750eb719ad092 upstream.

Recently I've been seeing xfs/051 fail on 1k block size filesystems.
Trying to trace the events during the test lead to the problem going
away, indicating that it was a race condition that lead to this
ASSERT failure:

XFS: Assertion failed: atomic_read(&pag->pag_ref) == 0, file: fs/xfs/xfs_mount.c, line: 156
.....
[<ffffffff814e1257>] xfs_free_perag+0x87/0xb0
[<ffffffff814e21b9>] xfs_mountfs+0x4d9/0x900
[<ffffffff814e5dff>] xfs_fs_fill_super+0x3bf/0x4d0
[<ffffffff811d8800>] mount_bdev+0x180/0x1b0
[<ffffffff814e3ff5>] xfs_fs_mount+0x15/0x20
[<ffffffff811d90a8>] mount_fs+0x38/0x170
[<ffffffff811f4347>] vfs_kern_mount+0x67/0x120
[<ffffffff811f7018>] do_mount+0x218/0xd60
[<ffffffff811f7e5b>] SyS_mount+0x8b/0xd0

When I finally caught it with tracing enabled, I saw that AG 2 had
an elevated reference count and a buffer was responsible for it. I
tracked down the specific buffer, and found that it was missing the
final reference count release that would put it back on the LRU and
hence be found by xfs_wait_buftarg() calls in the log mount failure
handling.

The last four traces for the buffer before the assert were (trimmed
for relevance)

kworker/0:1-5259   xfs_buf_iodone:        hold 2  lock 0 flags ASYNC
kworker/0:1-5259   xfs_buf_ioerror:       hold 2  lock 0 error -5
mount-7163	   xfs_buf_lock_done:     hold 2  lock 0 flags ASYNC
mount-7163	   xfs_buf_unlock:        hold 2  lock 1 flags ASYNC

This is an async write that is completing, so there's nobody waiting
for it directly.  Hence we call xfs_buf_relse() once all the
processing is complete. That does:

static inline void xfs_buf_relse(xfs_buf_t *bp)
{
	xfs_buf_unlock(bp);
	xfs_buf_rele(bp);
}

Now, it's clear that mount is waiting on the buffer lock, and that
it has been released by xfs_buf_relse() and gained by mount. This is
expected, because at this point the mount process is in
xfs_buf_delwri_submit() waiting for all the IO it submitted to
complete.

The mount process, however, is waiting on the lock for the buffer
because it is in xfs_buf_delwri_submit(). This waits for IO
completion, but it doesn't wait for the buffer reference owned by
the IO to go away. The mount process collects all the completions,
fails the log recovery, and the higher level code then calls
xfs_wait_buftarg() to free all the remaining buffers in the
filesystem.

The issue is that on unlocking the buffer, the scheduler has decided
that the mount process has higher priority than the the kworker
thread that is running the IO completion, and so immediately
switched contexts to the mount process from the semaphore unlock
code, hence preventing the kworker thread from finishing the IO
completion and releasing the IO reference to the buffer.

Hence by the time that xfs_wait_buftarg() is run, the buffer still
has an active reference and so isn't on the LRU list that the
function walks to free the remaining buffers. Hence we miss that
buffer and continue onwards to tear down the mount structures,
at which time we get find a stray reference count on the perag
structure. On a non-debug kernel, this will be ignored and the
structure torn down and freed. Hence when the kworker thread is then
rescheduled and the buffer released and freed, it will access a
freed perag structure.

The problem here is that when the log mount fails, we still need to
quiesce the log to ensure that the IO workqueues have returned to
idle before we run xfs_wait_buftarg(). By synchronising the
workqueues, we ensure that all IO completions are fully processed,
not just to the point where buffers have been unlocked. This ensures
we don't end up in the situation above.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Revert "xfs: clear PF_NOFREEZE for xfsaild kthread" 2016-02-25T20:01:24+00:00 Dave Chinner david@fromorbit.com 2016-01-18T21:21:46+00:00 16f14a28f660d0a3bdb169ebd17e0181c03d4778 commit 3e85286e75224fa3f08bdad20e78c8327742634e upstream. This reverts commit 24ba16bb3d499c49974669cd8429c3e4138ab102 as it prevents machines from suspending. This regression occurs when the xfsaild is idle on entry to suspend, and so there s no activity to wake it from it's idle sleep and hence see that it is supposed to freeze. Hence the freezer times out waiting for it and suspend is cancelled. There is no obvious fix for this short of freezing the filesystem properly, so revert this change for now. Signed-off-by: Dave Chinner <david@fromorbit.com> Acked-by: Jiri Kosina <jkosina@suse.cz> Reviewed-by: Brian Foster <bfoster@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 3e85286e75224fa3f08bdad20e78c8327742634e upstream.

This reverts commit 24ba16bb3d499c49974669cd8429c3e4138ab102 as it
prevents machines from suspending. This regression occurs when the
xfsaild is idle on entry to suspend, and so there s no activity to
wake it from it's idle sleep and hence see that it is supposed to
freeze. Hence the freezer times out waiting for it and suspend is
cancelled.

There is no obvious fix for this short of freezing the filesystem
properly, so revert this change for now.

Signed-off-by: Dave Chinner <david@fromorbit.com>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
xfs: inode recovery readahead can race with inode buffer creation 2016-02-25T20:01:24+00:00 Dave Chinner dchinner@redhat.com 2016-01-11T20:03:44+00:00 7530e6fdd9f207a6ebcf669490656def4f7cf73e commit b79f4a1c68bb99152d0785ee4ea3ab4396cdacc6 upstream. When we do inode readahead in log recovery, we do can do the readahead before we've replayed the icreate transaction that stamps the buffer with inode cores. The inode readahead verifier catches this and marks the buffer as !done to indicate that it doesn't yet contain valid inodes. In adding buffer error notification (i.e. setting b_error = -EIO at the same time as as we clear the done flag) to such a readahead verifier failure, we can then get subsequent inode recovery failing with this error: XFS (dm-0): metadata I/O error: block 0xa00060 ("xlog_recover_do..(read#2)") error 5 numblks 32 This occurs when readahead completion races with icreate item replay such as: inode readahead find buffer lock buffer submit RA io .... icreate recovery xfs_trans_get_buffer find buffer lock buffer <blocks on RA completion> ..... <ra completion> fails verifier clear XBF_DONE set bp->b_error = -EIO release and unlock buffer <icreate gains lock> icreate initialises buffer marks buffer as done adds buffer to delayed write queue releases buffer At this point, we have an initialised inode buffer that is up to date but has an -EIO state registered against it. When we finally get to recovering an inode in that buffer: inode item recovery xfs_trans_read_buffer find buffer lock buffer sees XBF_DONE is set, returns buffer sees bp->b_error is set fail log recovery! Essentially, we need xfs_trans_get_buf_map() to clear the error status of the buffer when doing a lookup. This function returns uninitialised buffers, so the buffer returned can not be in an error state and none of the code that uses this function expects b_error to be set on return. Indeed, there is an ASSERT(!bp->b_error); in the transaction case in xfs_trans_get_buf_map() that would have caught this if log recovery used transactions.... This patch firstly changes the inode readahead failure to set -EIO on the buffer, and secondly changes xfs_buf_get_map() to never return a buffer with an error state set so this first change doesn't cause unexpected log recovery failures. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit b79f4a1c68bb99152d0785ee4ea3ab4396cdacc6 upstream.

When we do inode readahead in log recovery, we do can do the
readahead before we've replayed the icreate transaction that stamps
the buffer with inode cores. The inode readahead verifier catches
this and marks the buffer as !done to indicate that it doesn't yet
contain valid inodes.

In adding buffer error notification  (i.e. setting b_error = -EIO at
the same time as as we clear the done flag) to such a readahead
verifier failure, we can then get subsequent inode recovery failing
with this error:

XFS (dm-0): metadata I/O error: block 0xa00060 ("xlog_recover_do..(read#2)") error 5 numblks 32

This occurs when readahead completion races with icreate item replay
such as:

	inode readahead
		find buffer
		lock buffer
		submit RA io
	....
	icreate recovery
	    xfs_trans_get_buffer
		find buffer
		lock buffer
		<blocks on RA completion>
	.....
	<ra completion>
		fails verifier
		clear XBF_DONE
		set bp->b_error = -EIO
		release and unlock buffer
	<icreate gains lock>
	icreate initialises buffer
	marks buffer as done
	adds buffer to delayed write queue
	releases buffer

At this point, we have an initialised inode buffer that is up to
date but has an -EIO state registered against it. When we finally
get to recovering an inode in that buffer:

	inode item recovery
	    xfs_trans_read_buffer
		find buffer
		lock buffer
		sees XBF_DONE is set, returns buffer
	    sees bp->b_error is set
		fail log recovery!

Essentially, we need xfs_trans_get_buf_map() to clear the error status of
the buffer when doing a lookup. This function returns uninitialised
buffers, so the buffer returned can not be in an error state and
none of the code that uses this function expects b_error to be set
on return. Indeed, there is an ASSERT(!bp->b_error); in the
transaction case in xfs_trans_get_buf_map() that would have caught
this if log recovery used transactions....

This patch firstly changes the inode readahead failure to set -EIO
on the buffer, and secondly changes xfs_buf_get_map() to never
return a buffer with an error state set so this first change doesn't
cause unexpected log recovery failures.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
libxfs: pack the agfl header structure so XFS_AGFL_SIZE is correct 2016-02-25T20:01:24+00:00 Darrick J. Wong darrick.wong@oracle.com 2016-01-04T05:13:21+00:00 888959f2fd5042609f1beefe663ced4dea4dc109 commit 96f859d52bcb1c6ea6f3388d39862bf7143e2f30 upstream. Because struct xfs_agfl is 36 bytes long and has a 64-bit integer inside it, gcc will quietly round the structure size up to the nearest 64 bits -- in this case, 40 bytes. This results in the XFS_AGFL_SIZE macro returning incorrect results for v5 filesystems on 64-bit machines (118 items instead of 119). As a result, a 32-bit xfs_repair will see garbage in AGFL item 119 and complain. Therefore, tell gcc not to pad the structure so that the AGFL size calculation is correct. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 96f859d52bcb1c6ea6f3388d39862bf7143e2f30 upstream.

Because struct xfs_agfl is 36 bytes long and has a 64-bit integer
inside it, gcc will quietly round the structure size up to the nearest
64 bits -- in this case, 40 bytes.  This results in the XFS_AGFL_SIZE
macro returning incorrect results for v5 filesystems on 64-bit
machines (118 items instead of 119).  As a result, a 32-bit xfs_repair
will see garbage in AGFL item 119 and complain.

Therefore, tell gcc not to pad the structure so that the AGFL size
calculation is correct.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ovl: setattr: check permissions before copy-up 2016-02-25T20:01:24+00:00 Miklos Szeredi miklos@szeredi.hu 2015-12-11T15:30:49+00:00 8373f6590f6b371bff2c5f2c0581548eb0192014 commit cf9a6784f7c1b5ee2b9159a1246e327c331c5697 upstream. Without this copy-up of a file can be forced, even without actually being allowed to do anything on the file. [Arnd Bergmann] include <linux/pagemap.h> for PAGE_CACHE_SIZE (used by MAX_LFS_FILESIZE definition). Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit cf9a6784f7c1b5ee2b9159a1246e327c331c5697 upstream.

Without this copy-up of a file can be forced, even without actually being
allowed to do anything on the file.

[Arnd Bergmann] include <linux/pagemap.h> for PAGE_CACHE_SIZE (used by
MAX_LFS_FILESIZE definition).

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ovl: root: copy attr 2016-02-25T20:01:24+00:00 Miklos Szeredi miklos@szeredi.hu 2015-12-09T15:11:59+00:00 7193e802960f884e0ae6c40711c4e3c70fa3b070 commit ed06e069775ad9236087594a1c1667367e983fb5 upstream. We copy i_uid and i_gid of underlying inode into overlayfs inode. Except for the root inode. Fix this omission. Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit ed06e069775ad9236087594a1c1667367e983fb5 upstream.

We copy i_uid and i_gid of underlying inode into overlayfs inode.  Except
for the root inode.

Fix this omission.

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ovl: check dentry positiveness in ovl_cleanup_whiteouts() 2016-02-25T20:01:24+00:00 Konstantin Khlebnikov khlebnikov@yandex-team.ru 2015-11-16T15:44:11+00:00 367e439dbc238907963ddf2758200b55087cab04 commit 84889d49335627bc770b32787c1ef9ebad1da232 upstream. This patch fixes kernel crash at removing directory which contains whiteouts from lower layers. Cache of directory content passed as "list" contains entries from all layers, including whiteouts from lower layers. So, lookup in upper dir (moved into work at this stage) will return negative entry. Plus this cache is filled long before and we can race with external removal. Example: mkdir -p lower0/dir lower1/dir upper work overlay touch lower0/dir/a lower0/dir/b mknod lower1/dir/a c 0 0 mount -t overlay none overlay -o lowerdir=lower1:lower0,upperdir=upper,workdir=work rm -fr overlay/dir Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 84889d49335627bc770b32787c1ef9ebad1da232 upstream.

This patch fixes kernel crash at removing directory which contains
whiteouts from lower layers.

Cache of directory content passed as "list" contains entries from all
layers, including whiteouts from lower layers. So, lookup in upper dir
(moved into work at this stage) will return negative entry. Plus this
cache is filled long before and we can race with external removal.

Example:
 mkdir -p lower0/dir lower1/dir upper work overlay
 touch lower0/dir/a lower0/dir/b
 mknod lower1/dir/a c 0 0
 mount -t overlay none overlay -o lowerdir=lower1:lower0,upperdir=upper,workdir=work
 rm -fr overlay/dir

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ovl: use a minimal buffer in ovl_copy_xattr 2016-02-25T20:01:24+00:00 Vito Caputo vito.caputo@coreos.com 2015-10-24T12:19:46+00:00 fa932190a5f332e1936ab0223c7c5d79b5596a9c commit e4ad29fa0d224d05e08b2858e65f112fd8edd4fe upstream. Rather than always allocating the high-order XATTR_SIZE_MAX buffer which is costly and prone to failure, only allocate what is needed and realloc if necessary. Fixes https://github.com/coreos/bugs/issues/489 Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit e4ad29fa0d224d05e08b2858e65f112fd8edd4fe upstream.

Rather than always allocating the high-order XATTR_SIZE_MAX buffer
which is costly and prone to failure, only allocate what is needed and
realloc if necessary.

Fixes https://github.com/coreos/bugs/issues/489

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ovl: allow zero size xattr 2016-02-25T20:01:23+00:00 Miklos Szeredi miklos@szeredi.hu 2015-11-10T16:08:41+00:00 85a7ed329aca5efd0eb70789db145a1e989c7a53 commit 97daf8b97ad6f913a34c82515be64dc9ac08d63e upstream. When ovl_copy_xattr() encountered a zero size xattr no more xattrs were copied and the function returned success. This is clearly not the desired behavior. Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 97daf8b97ad6f913a34c82515be64dc9ac08d63e upstream.

When ovl_copy_xattr() encountered a zero size xattr no more xattrs were
copied and the function returned success.  This is clearly not the desired
behavior.

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>