[XFS] Ensure a frozen filesystem has a clean log before writing the dummy

[safe/jmp/linux-2.6] / fs / xfs / xfs_vfsops.c

diff --git a/fs/xfs/xfs_vfsops.c b/fs/xfs/xfs_vfsops.c
index f5ea74b..c2a6eab 100644 (file)
--- 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);