[PATCH 09/27] xfs: fix filesystsem freeze race in xfs_trans_alloc

[Alex Elder]

On Fri, 2011-07-01 at 05:43 -0400, Christoph Hellwig wrote:
> As pointed out by Jan xfs_trans_alloc can race with a concurrent filesystem
> freeze when it sleeps during the memory allocation.  Fix this by moving the
> wait_for_freeze call after the memory allocation.  This means moving the
> freeze into the low-level _xfs_trans_alloc helper, which thus grows a new
> argument.  Also fix up some comments in that area while at it.
> 
> Signed-off-by: Christoph Hellwig <hch at lst.de>
> Reviewed-by: Dave Chinner <david at fromorbit.com>

Looks good.  The race has to do with the check of
mp->m_active_trans in xfs_quiesce_attr(), which
is called by the freeze_fs method, xfs_fs_freeze()

Reviewed-by: Alex Elder <aelder at sgi.com>