tree 67ea83476070ca516321645cc1b775b5ddd91c14
parent e7bde7c73957cfda82963127421069d13a44e921
author Christoph Hellwig <hch@infradead.org> 1318947799 -0400
committer Greg Kroah-Hartman <gregkh@suse.de> 1319519416 +0200

xfs: revert to using a kthread for AIL pushing

commit 0030807c66f058230bcb20d2573bcaf28852e804 upstream

Currently we have a few issues with the way the workqueue code is used to
implement AIL pushing:

 - it accidentally uses the same workqueue as the syncer action, and thus
   can be prevented from running if there are enough sync actions active
   in the system.
 - it doesn't use the HIGHPRI flag to queue at the head of the queue of
   work items

At this point I'm not confident enough in getting all the workqueue flags and
tweaks right to provide a perfectly reliable execution context for AIL
pushing, which is the most important piece in XFS to make forward progress
when the log fills.

Revert back to use a kthread per filesystem which fixes all the above issues
at the cost of having a task struct and stack around for each mounted
filesystem.  In addition this also gives us much better ways to diagnose
any issues involving hung AIL pushing and removes a small amount of code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reported-by: Stefan Priebe <s.priebe@profihost.ag>
Tested-by: Stefan Priebe <s.priebe@profihost.ag>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>