[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>

1 files changed, 9 insertions, 18 deletions

diff --git a/fs/xfs/xfs_vfsops.c b/fs/xfs/xfs_vfsops.c
index f0e09ca14139..36ea1b2094f2 100644
--- 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;
 }