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  1. 19 May, 2011 5 commits
    • Dave Chinner's avatar
      xfs: reset buffer pointers before freeing them · 44396476
      Dave Chinner authored 
      When we free a vmapped buffer, we need to ensure the vmap address
and length we free is the same as when it was allocated. In various
places in the log code we change the memory the buffer is pointing
to before issuing IO, but we never reset the buffer to point back to
it's original memory (or no memory, if that is the case for the
buffer).

As a result, when we free the buffer it points to memory that is
owned by something else and attempts to unmap and free it. Because
the range does not match any known mapped range, it can trigger
BUG_ON() traps in the vmap code, and potentially corrupt the vmap
area tracking.

Fix this by always resetting these buffers to their original state
before freeing them.
Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAlex Elder <aelder@sgi.com>
      44396476
    • Dave Chinner's avatar
      xfs: avoid getting stuck during async inode flushes · ee58abdf
      Dave Chinner authored 
      When the underlying inode buffer is locked and xfs_sync_inode_attr()
is doing a non-blocking flush, xfs_iflush() can return EAGAIN.  When
this happens, clear the error rather than returning it to
xfs_inode_ag_walk(), as returning EAGAIN will result in the AG walk
delaying for a short while and trying again. This can result in
background walks getting stuck on the one AG until inode buffer is
unlocked by some other means.

This behaviour was noticed when analysing event traces followed by
code inspection and verification of the fix via further traces.
Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAlex Elder <aelder@sgi.com>
      ee58abdf
    • Dave Chinner's avatar
      xfs: fix xfs_itruncate_start tracing · e5737515
      Dave Chinner authored 
      Variables are ordered incorrectly in trace call.
Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAlex Elder <aelder@sgi.com>
      e5737515
    • Dave Chinner's avatar
      xfs: fix duplicate workqueue initialisation · 1beb65ad
      Dave Chinner authored 
      The workqueue initialisation function is called twice when
initialising the XFS subsystem. Remove the second initialisation
call.
Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
Signed-off-by: default avatarAlex Elder <aelder@sgi.com>
      1beb65ad
    • Joe Perches's avatar
      xfs: kill off xfs_printk() · e69522a8
      Joe Perches authored 
      xfs_alert_tag() can be defined using xfs_alert(), and thereby avoid
using xfs_printk() altogether.  This is the only remaining use of
xfs_printk(), so changing it this way means xfs_printk() can simply
be eliminated.can simply be eliminated.can simply be eliminated.can
simply be eliminated.can simply be eliminated.can simply be
eliminated.can simply be eliminated.can simply be eliminated.can
simply be eliminated.

Also add format checking to the non-debug inline function xfs_debug.
Miscellaneous function prototype argument alignment.

(Updated to delete the definition of xfs_printk(), which is
no longer used or needed.)
Signed-off-by: default avatarJoe Perches <joe@perches.com>
Signed-off-by: default avatarAlex Elder <aelder@sgi.com>
      e69522a8
  3. 09 May, 2011 5 commits
    • Dave Chinner's avatar
      xfs: fix race condition in AIL push trigger · e4d3c4a4
      Dave Chinner authored 
      The recent conversion of the xfsaild functionality to a work queue
introduced a hard-to-hit log space grant hang. One is caused by a
race condition in determining whether there is a psh in progress or
not.

The XFS_AIL_PUSHING_BIT is used to determine whether a push is
currently in progress.  When the AIL push work completes, it checked
whether the target changed and cleared the PUSHING bit to allow a
new push to be requeued. The race condition is as follows:

	Thread 1		push work

	smp_wmb()
				smp_rmb()
				check ailp->xa_target unchanged
	update ailp->xa_target
	test/set PUSHING bit
	does not queue
				clear PUSHING bit
				does not requeue

Now that the push target is updated, new attempts to push the AIL
will not trigger as the push target will be the same, and hence
despite trying to push the AIL we won't ever wake it again.

The fix is to ensure that the AIL push work clears the PUSHING bit
before it checks if the target is unchanged.

As a result, both push triggers operate on the same test/set bit
criteria, so even if we race in the push work and miss the target
update, the thread requesting the push will still set the PUSHING
bit and queue the push work to occur. For safety sake, the same
queue check is done if the push work detects the target change,
though only one of the two will will queue new work due to the use
of test_and_set_bit() checks.
Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarAlex Elder <aelder@sgi.com>
      e4d3c4a4
    • Dave Chinner's avatar
      xfs: make AIL target updates and compares 32bit safe. · fd5670f2
      Dave Chinner authored 
      The recent conversion of the xfsaild functionality to a work queue
introduced a hard-to-hit log space grant hang. One of the problems
noticed was that updates of the push target are not 32 bit safe as
the target is a 64 bit value.

We cannot copy a 64 bit LSN without the possibility of corrupting
the result when racing with another updating thread. We have
function to do this update safely without needing to care about
32/64 bit issues - xfs_trans_ail_copy_lsn() - so use that when
updating the AIL push target.

Also move the reading of the target in the push work inside the AIL
lock, and use XFS_LSN_CMP() for the unlocked comparison during work
termination to close read holes as well.
Signed-off-by: default avatarDave Chinner <david@fromorbit.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarAlex Elder <aelder@sgi.com>
      fd5670f2
    • Dave Chinner's avatar
      xfs: always push the AIL to the target · cb64026b
      Dave Chinner authored 
      The recent conversion of the xfsaild functionality to a work queue
introduced a hard-to-hit log space grant hang. One of the problems
discovered is a target mismatch between the item pushing loop and
the target itself.

The push trigger checks for the target increasing (i.e. new target >
current) while the push loop only pushes items that have a LSN <
current. As a result, we can get the situation where the push target
is X, the items at the tail of the AIL have LSN X and they don't get
pushed. The push work then completes thinking it is done, and cannot
be restarted until the push target increases to >= X + 1. If the
push target then never increases (because the tail is not moving),
then we never run the push work again and we stall.

Fix it by making sure log items with a LSN that matches the target
exactly are pushed during the loop.
Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarAlex Elder <aelder@sgi.com>
      cb64026b
    • Dave Chinner's avatar
      xfs: exit AIL push work correctly when AIL is empty · ea35a200
      Dave Chinner authored 
      The recent conversion of the xfsaild functionality to a work queue
introduced a hard-to-hit log space grant hang. The main cause is a
regression where a work exit path fails to clear the PUSHING state
and recheck the target correctly.

Make both exit paths do the same PUSHING bit clearing and target
checking when the "no more work to be done" condition is hit.
Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarAlex Elder <aelder@sgi.com>
      ea35a200
    • Dave Chinner's avatar
      xfs: ensure reclaim cursor is reset correctly at end of AG · b2232219
      Dave Chinner authored 
      On a 32 bit highmem PowerPC machine, the XFS inode cache was growing
without bound and exhausting low memory causing the OOM killer to be
triggered. After some effort, the problem was reproduced on a 32 bit
x86 highmem machine.

The problem is that the per-ag inode reclaim index cursor was not
getting reset to the start of the AG if the radix tree tag lookup
found no more reclaimable inodes. Hence every further reclaim
attempt started at the same index beyond where any reclaimable
inodes lay, and no further background reclaim ever occurred from the
AG.

Without background inode reclaim the VM driven cache shrinker
simply cannot keep up with cache growth, and OOM is the result.

While the change that exposed the problem was the conversion of the
inode reclaim to use work queues for background reclaim, it was not
the cause of the bug. The bug was introduced when the cursor code
was added, just waiting for some weird configuration to strike....
Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
Tested-By: default avatarChristian Kujau <lists@nerdbynature.de>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarAlex Elder <aelder@sgi.com>
      b2232219
  5. 28 Apr, 2011 7 commits
  7. 20 Apr, 2011 1 commit
  9. 19 Apr, 2011 1 commit
  11. 18 Apr, 2011 21 commits
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