On 07/20/12 08:21, Mark Tinguely wrote:
On 07/18/12 20:58, Dave Chinner wrote:
On Wed, Jul 18, 2012 at 12:33:58PM -0500, tinguely@xxxxxxx wrote:
Sorry, I have been distracted away from this regression. This was
previously
titled "xfs: synchronously write the superblock on unmount".
xfs_wait_buftarg() does not wait for the completion of the write of the
uncached superblock. This write can race with the shutdown of the log
and
causes a panic if the write does not win the race.
The log write of the superblock is important for possible recovery,
but a
second syncronous write of the same superblock seems redundant. Would
just
waiting for the iodone() of the log write before tearing down the log be
enough?
Yes. i.e. something like:
/*
* The superblock buffer is uncached, so xfs_wait_buftarg()
* will not wait for it. Hence we need to explicitly wait
* for IO completion on the superblock to occur here.
*/
error = xfs_buf_iowait(mp->m_sb_bp);
if (error)
AAAAIEEEE!
This fix is also needed in xfs_quiesce_attr() for the freeze and
ro,remount cases as well.
Cheers,
Dave.
Thanks for the feedback.
I chose the ugly lock to block on the superblock buffer because it has
XBF_ASYNC set at that point and won't go through the complete() patch. I
will look at turning the XBF_ASYNC flag off and wait on a xfs_buf_iowait().
--Mark.
Looks like the xfsaild_push() sets the XBF_ASYNC flag on the superblock
buffer. Waiting on the xfs_buf_iowait() won't work but have to use the
less elegant lock.
--Mark.
_______________________________________________
xfs mailing list
xfs@xxxxxxxxxxx
http://oss.sgi.com/mailman/listinfo/xfs
