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xfs: prevent unwritten extent conversion from blocking I/O completion

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Unwritten extent conversion can recurse back into the filesystem due
to memory allocation. Memory reclaim requires I/O completions to be
processed to allow the callers to make progress. If the I/O
completion workqueue thread is doing the recursion, then we have a
deadlock situation.

Move unwritten extent completion into it's own workqueue so it
doesn't block I/O completions for normal delayed allocation or
overwrite data.

Signed-off-by: Dave Chinner <david@fromorbit.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Dave Chinner
2009-04-06 18:42:11 +02:00
committed by Christoph Hellwig
parent 705db3fd46
commit c626d174cf
3 changed files with 31 additions and 17 deletions
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38
fs/xfs/linux-2.6/xfs_aops.c
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@ -152,23 +152,6 @@ xfs_find_bdev_for_inode(
return mp->m_ddev_targp->bt_bdev;
}
/*
* Schedule IO completion handling on a xfsdatad if this was
* the final hold on this ioend. If we are asked to wait,
* flush the workqueue.
*/
STATIC void
xfs_finish_ioend(
xfs_ioend_t *ioend,
int wait)
{
if (atomic_dec_and_test(&ioend->io_remaining)) {
queue_work(xfsdatad_workqueue, &ioend->io_work);
if (wait)
flush_workqueue(xfsdatad_workqueue);
}
}
/*
* We're now finished for good with this ioend structure.
* Update the page state via the associated buffer_heads,
@ -309,6 +292,27 @@ xfs_end_bio_read(
xfs_destroy_ioend(ioend);
}
/*
* Schedule IO completion handling on a xfsdatad if this was
* the final hold on this ioend. If we are asked to wait,
* flush the workqueue.
*/
STATIC void
xfs_finish_ioend(
xfs_ioend_t *ioend,
int wait)
{
if (atomic_dec_and_test(&ioend->io_remaining)) {
struct workqueue_struct *wq = xfsdatad_workqueue;
if (ioend->io_work.func == xfs_end_bio_unwritten)
wq = xfsconvertd_workqueue;
queue_work(wq, &ioend->io_work);
if (wait)
flush_workqueue(wq);
}
}
/*
* Allocate and initialise an IO completion structure.
* We need to track unwritten extent write completion here initially.