[XFS] Write log dummy record when freezing filesystem

SGI-PV: 945483
SGI-Modid: xfs-linux-melb:xfs-kern:202638a

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

fs/xfs/xfs_fsops.c

@@ -540,6 +540,32 @@ xfs_reserve_blocks(
 	return(0);
 }
 
+void
+xfs_fs_log_dummy(xfs_mount_t *mp)
+{
+	xfs_trans_t *tp;
+	xfs_inode_t *ip;
+
+
+	tp = _xfs_trans_alloc(mp, XFS_TRANS_DUMMY1);
+	atomic_inc(&mp->m_active_trans);
+	if (xfs_trans_reserve(tp, 0, XFS_ICHANGE_LOG_RES(mp), 0, 0, 0)) {
+		xfs_trans_cancel(tp, 0);
+		return;
+	}
+
+	ip = mp->m_rootip;
+	xfs_ilock(ip, XFS_ILOCK_EXCL);
+
+	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
+	xfs_trans_ihold(tp, ip);
+	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
+	xfs_trans_set_sync(tp);
+	xfs_trans_commit(tp, 0, NULL);
+
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
+}
+
 int
 xfs_fs_goingdown(
 	xfs_mount_t	*mp,

fs/xfs/xfs_fsops.h

@@ -25,5 +25,6 @@ extern int xfs_fs_counts(xfs_mount_t *mp, xfs_fsop_counts_t *cnt);
 extern int xfs_reserve_blocks(xfs_mount_t *mp, __uint64_t *inval,
 				xfs_fsop_resblks_t *outval);
 extern int xfs_fs_goingdown(xfs_mount_t *mp, __uint32_t inflags);
+extern void xfs_fs_log_dummy(xfs_mount_t *mp);
 
 #endif	/* __XFS_FSOPS_H__ */

fs/xfs/xfs_vfsops.c

@@ -53,6 +53,7 @@
 #include "xfs_acl.h"
 #include "xfs_attr.h"
 #include "xfs_clnt.h"
+#include "xfs_fsops.h"
 
 STATIC int xfs_sync(bhv_desc_t *, int, cred_t *);
 
@@ -1967,6 +1968,7 @@ xfs_freeze(
 	/* Push the superblock and write an unmount record */
 	xfs_log_unmount_write(mp);
 	xfs_unmountfs_writesb(mp);
+	xfs_fs_log_dummy(mp);
 }