1 files changed, 22 insertions, 4 deletions

diff --git a/fs/xfs/xfs_vfsops.c b/fs/xfs/xfs_vfsops.c
index f5ea74b999b6..c2a6eab7fa2d 100644
--- a/fs/xfs/xfs_vfsops.c
+++ b/fs/xfs/xfs_vfsops.c
@@ -872,6 +872,10 @@ xfs_statvfs(
  *                     this by simply making sure the log gets flushed
  *                     if SYNC_BDFLUSH is set, and by actually writing it
  *                     out otherwise.
+ *      SYNC_DIO_WAIT - The caller wants us to wait for all direct I/Os
+ *                     as well to ensure all data I/O completes before we
+ *                     return. Forms the drain side of the write barrier needed
+ *                     to safely quiesce the filesystem.
  *
  */
 /*ARGSUSED*/
@@ -883,10 +887,7 @@ xfs_sync(
 {
         xfs_mount_t     *mp = XFS_BHVTOM(bdp);
 
-        if (unlikely(flags == SYNC_QUIESCE))
-                return xfs_quiesce_fs(mp);
-        else
-                return xfs_syncsub(mp, flags, NULL);
+        return xfs_syncsub(mp, flags, NULL);
 }
 
 /*
@@ -1172,6 +1173,12 @@ xfs_sync_inodes(
                         }
 
                 }
+                /*
+                 * When freezing, we need to wait ensure direct I/O is complete
+                 * as well to ensure all data modification is complete here
+                 */
+                if (flags & SYNC_DIO_WAIT)
+                        vn_iowait(vp);
 
                 if (flags & SYNC_BDFLUSH) {
                         if ((flags & SYNC_ATTR) &&
@@ -1950,15 +1957,26 @@ xfs_showargs(
         return 0;
 }
 
+/*
+ * Second stage of a freeze. The data is already frozen, now we have to take
+ * care of the metadata. New transactions are already blocked, so we need to
+ * wait for any remaining transactions to drain out before proceding.
+ */
 STATIC void
 xfs_freeze(
         bhv_desc_t      *bdp)
 {
         xfs_mount_t     *mp = XFS_BHVTOM(bdp);
 
+        /* wait for all modifications to complete */
         while (atomic_read(&mp->m_active_trans) > 0)
                 delay(100);
 
+        /* flush inodes and push all remaining buffers out to disk */
+        xfs_quiesce_fs(mp);
+
+        BUG_ON(atomic_read(&mp->m_active_trans) > 0);
+
         /* Push the superblock and write an unmount record */
         xfs_log_unmount_write(mp);
         xfs_unmountfs_writesb(mp);