xfs: move the log ioend workqueue to struct xlog

Move the workqueue used for log I/O completions from struct xfs_mount
to struct xlog to keep it self contained in the log code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
[darrick: destroy the log workqueue after ensuring log ios are done]
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h
index b9c90ab..a20f5e9 100644
--- a/fs/xfs/xfs_log_priv.h
+++ b/fs/xfs/xfs_log_priv.h
@@ -357,6 +357,7 @@ struct xlog {
 	struct xfs_ail		*l_ailp;	/* AIL log is working with */
 	struct xfs_cil		*l_cilp;	/* CIL log is working with */
 	struct xfs_buftarg	*l_targ;        /* buftarg of log */
+	struct workqueue_struct	*l_ioend_workqueue; /* for I/O completions */
 	struct delayed_work	l_work;		/* background flush work */
 	uint			l_flags;
 	uint			l_quotaoffs_flag; /* XFS_DQ_*, for QUOTAOFFs */