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
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);
This fix is also needed in xfs_quiesce_attr() for the freeze and
ro,remount cases as well.