[3.0-stable PATCH 27/36] xfs: protect xfs_sync_worker with s_umount semaphore

[Dave Chinner]

On Mon, Dec 03, 2012 at 05:42:35PM -0600, Mark Tinguely wrote:
> From: Ben Myers <bpm at sgi.com>
> 
> Upstream commit: 1307bbd2af67283131728637e9489002adb26f10
> 
> xfs_sync_worker checks the MS_ACTIVE flag in s_flags to avoid doing
> work during mount and unmount.  This flag can be cleared by unmount
> after the xfs_sync_worker checks it but before the work is completed.
> The has caused crashes in the completion handler for the dummy
> transaction commited by xfs_sync_worker:

This doesn't belong in a stable kernel. It was wrong when it was
originally committed, it's wrong to backport it.

Cheers,

Dave.
-- 
Dave Chinner
david at fromorbit.com