[XFS] quiesce the filesystem proper when freezing

SGI-PV: 936977
SGI-Modid: xfs-linux:xfs-kern:193840a

Signed-off-by: Christoph Hellwig <hch@sgi.com>
Signed-off-by: Nathan Scott <nathans@sgi.com>

fs/xfs/linux-2.6/xfs_super.c

@@ -590,8 +590,10 @@ linvfs_sync_super(
 	int		error;
 	int		flags = SYNC_FSDATA;
 
-	if (wait)
+	if (unlikely(sb->s_frozen == SB_FREEZE_WRITE))
-		flags |= SYNC_WAIT;
+		flags = SYNC_QUIESCE;
+	else
+		flags = SYNC_FSDATA | (wait ? SYNC_WAIT : 0);
 
 	VFS_SYNC(vfsp, flags, NULL, error);
 	sb->s_dirt = 0;

fs/xfs/linux-2.6/xfs_vfs.h

@@ -107,6 +107,7 @@ typedef enum {
 #define SYNC_FSDATA		0x0020	/* flush fs data (e.g. superblocks) */
 #define SYNC_REFCACHE		0x0040  /* prune some of the nfs ref cache */
 #define SYNC_REMOUNT		0x0080  /* remount readonly, no dummy LRs */
+#define SYNC_QUIESCE		0x0100  /* quiesce fileystem for a snapshot */
 
 typedef int	(*vfs_mount_t)(bhv_desc_t *,
 				struct xfs_mount_args *, struct cred *);

fs/xfs/xfs_vfsops.c

@@ -612,29 +612,12 @@ out:
 	return XFS_ERROR(error);
 }
 
-#define REMOUNT_READONLY_FLAGS	(SYNC_REMOUNT|SYNC_ATTR|SYNC_WAIT)
-
 STATIC int
-xfs_mntupdate(
+xfs_quiesce_fs(
-	bhv_desc_t			*bdp,
+	xfs_mount_t		*mp)
-	int				*flags,
-	struct xfs_mount_args		*args)
 {
-	struct vfs	*vfsp = bhvtovfs(bdp);
+	int			count = 0, pincount;
-	xfs_mount_t	*mp = XFS_BHVTOM(bdp);
-	int		pincount, error;
-	int		count = 0;
 		
-	if (args->flags & XFSMNT_NOATIME)
-		mp->m_flags |= XFS_MOUNT_NOATIME;
-	else
-		mp->m_flags &= ~XFS_MOUNT_NOATIME;
-
-	if (!(vfsp->vfs_flag & VFS_RDONLY)) {
-		VFS_SYNC(vfsp, SYNC_FSDATA|SYNC_BDFLUSH|SYNC_ATTR, NULL, error);
-	}
-
-	if (*flags & MS_RDONLY) {
 	xfs_refcache_purge_mp(mp);
 	xfs_flush_buftarg(mp->m_ddev_targp, 0);
 	xfs_finish_reclaim_all(mp, 0);
@@ -647,7 +630,7 @@ xfs_mntupdate(
 	 * we can write the unmount record.
 	 */ 
 	do {
-			VFS_SYNC(vfsp, REMOUNT_READONLY_FLAGS, NULL, error);
+		xfs_syncsub(mp, SYNC_REMOUNT|SYNC_ATTR|SYNC_WAIT, 0, NULL);
 		pincount = xfs_flush_buftarg(mp->m_ddev_targp, 1);
 		if (!pincount) {
 			delay(50);
@@ -655,6 +638,31 @@ xfs_mntupdate(
 		}
 	} while (count < 2);
 
+	return 0;
+}
+
+STATIC int
+xfs_mntupdate(
+	bhv_desc_t			*bdp,
+	int				*flags,
+	struct xfs_mount_args		*args)
+{
+	struct vfs	*vfsp = bhvtovfs(bdp);
+	xfs_mount_t	*mp = XFS_BHVTOM(bdp);
+	int		error;
+
+	if (args->flags & XFSMNT_NOATIME)
+		mp->m_flags |= XFS_MOUNT_NOATIME;
+	else
+		mp->m_flags &= ~XFS_MOUNT_NOATIME;
+
+	if (!(vfsp->vfs_flag & VFS_RDONLY)) {
+		VFS_SYNC(vfsp, SYNC_FSDATA|SYNC_BDFLUSH|SYNC_ATTR, NULL, error);
+	}
+
+	if (*flags & MS_RDONLY) {
+		xfs_quiesce_fs(mp);
+
 		/* Ok now write out an unmount record */
 		xfs_log_unmount_write(mp);
 		xfs_unmountfs_writesb(mp);
@@ -869,10 +877,12 @@ xfs_sync(
 	int		flags,
 	cred_t		*credp)
 {
-	xfs_mount_t	*mp;
+	xfs_mount_t	*mp = XFS_BHVTOM(bdp);
 
-	mp = XFS_BHVTOM(bdp);
+	if (unlikely(flags == SYNC_QUIESCE))
-	return (xfs_syncsub(mp, flags, 0, NULL));
+		return xfs_quiesce_fs(mp);
+	else
+		return xfs_syncsub(mp, flags, 0, NULL);
 }
 
 /*