[XFS] Fix a possible forced shutdown due to mishandling write barriers

with remount,ro.

SGI-PV: 951944
SGI-Modid: xfs-linux-melb:xfs-kern:25742a

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

diff --git a/fs/xfs/xfs_vfsops.c b/fs/xfs/xfs_vfsops.c
index f0e09ca1413933fa01993a0555beb80e38bbe14b..36ea1b2094f29cf6c2a475fce994e8e15a4e0008 100644 (file)
--- a/fs/xfs/xfs_vfsops.c
+++ b/fs/xfs/xfs_vfsops.c
@@ -669,31 +669,22 @@ xfs_mntupdate(
        xfs_mount_t     *mp = XFS_BHVTOM(bdp);
        int             error;
 
-       if (args->flags & XFSMNT_BARRIER)
-               mp->m_flags |= XFS_MOUNT_BARRIER;
-       else
-               mp->m_flags &= ~XFS_MOUNT_BARRIER;
-
-       if ((vfsp->vfs_flag & VFS_RDONLY) &&
-           !(*flags & MS_RDONLY)) {
-               vfsp->vfs_flag &= ~VFS_RDONLY;
-
-               if (args->flags & XFSMNT_BARRIER)
+       if (!(*flags & MS_RDONLY)) {                    /* rw/ro -> rw */
+               if (vfsp->vfs_flag & VFS_RDONLY)
+                       vfsp->vfs_flag &= ~VFS_RDONLY;
+               if (args->flags & XFSMNT_BARRIER) {
+                       mp->m_flags |= XFS_MOUNT_BARRIER;
                        xfs_mountfs_check_barriers(mp);
-       }
-
-       if (!(vfsp->vfs_flag & VFS_RDONLY) &&
-           (*flags & MS_RDONLY)) {
+               } else {
+                       mp->m_flags &= ~XFS_MOUNT_BARRIER;
+               }
+       } else if (!(vfsp->vfs_flag & VFS_RDONLY)) {    /* rw -> ro */
                VFS_SYNC(vfsp, SYNC_FSDATA|SYNC_BDFLUSH|SYNC_ATTR, NULL, error);
-
                xfs_quiesce_fs(mp);
-
-               /* Ok now write out an unmount record */
                xfs_log_unmount_write(mp);
                xfs_unmountfs_writesb(mp);
                vfsp->vfs_flag |= VFS_RDONLY;
        }
-
        return 0;
 }