Still seeing hangs in xlog_grant_log_space

[Peter Watkins]

Does your kernel have the effect of

0bf6a5bd4b55b466964ead6fa566d8f346a828ee xfs: convert the xfsaild
thread to a workqueue
c7eead1e118fb7e34ee8f5063c3c090c054c3820 xfs: revert to using a
kthread for AIL pushing

In particular, is this code in xfs_trans_ail_push:

       smp_wmb();
       xfs_trans_ail_copy_lsn(ailp, &ailp->xa_target, &threshold_lsn);
       smp_wmb();