[18/27] xfs: do not update xa_last_pushed_lsn for locked items

[Greg KH]

3.0-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Christoph Hellwig <hch@xxxxxxxxxxxxx>

commit bc6e588a8971aa74c02e42db4d6e0248679f3738 upstream

If an item was locked we should not update xa_last_pushed_lsn and thus skip
it when restarting the AIL scan as we need to be able to lock and write it
out as soon as possible.  Otherwise heavy lock contention might starve AIL
pushing too easily, especially given the larger backoff once we moved
xa_last_pushed_lsn all the way to the target lsn.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Reported-by: Stefan Priebe <s.priebe@xxxxxxxxxxxx>
Tested-by: Stefan Priebe <s.priebe@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 fs/xfs/xfs_trans_ail.c |    1 -
 1 file changed, 1 deletion(-)

--- a/fs/xfs/xfs_trans_ail.c
+++ b/fs/xfs/xfs_trans_ail.c
@@ -491,7 +491,6 @@ xfs_ail_worker(
 
 		case XFS_ITEM_LOCKED:
 			XFS_STATS_INC(xs_push_ail_locked);
-			ailp->xa_last_pushed_lsn = lsn;
 			stuck++;
 			break;
 


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