ocfs2: manually d_move() during ocfs2_rename()

Make use of FS_RENAME_DOES_D_MOVE to avoid a race condition that can occur
during ->rename() if we d_move() outside of the parent directory cluster
locks, and another node discovers the new name (created during the rename)
and unlinks it. d_move() will unconditionally rehash a dentry - which will
leave stale data in the system.
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

fs/ocfs2/dcache.c

@@ -414,7 +414,7 @@ void ocfs2_dentry_move(struct dentry *dentry, struct dentry *target,
 	 * XXX: Is there any advantage to dropping the lock here?
 	 */
 	if (old_dir == new_dir)
-		return;
+		goto out_move;
 
 	ocfs2_dentry_lock_put(osb, dentry->d_fsdata);
 
@@ -423,6 +423,9 @@ void ocfs2_dentry_move(struct dentry *dentry, struct dentry *target,
 				       OCFS2_I(new_dir)->ip_blkno, 0);
 	if (ret)
 		mlog_errno(ret);
+
+out_move:
+	d_move(dentry, target);
 }
 
 struct dentry_operations ocfs2_dentry_ops = {

fs/ocfs2/super.c

@@ -682,7 +682,7 @@ static struct file_system_type ocfs2_fs_type = {
 	.kill_sb        = kill_block_super, /* set to the generic one
 					     * right now, but do we
 					     * need to change that? */
-	.fs_flags       = FS_REQUIRES_DEV,
+	.fs_flags       = FS_REQUIRES_DEV|FS_RENAME_DOES_D_MOVE,
 	.next           = NULL
 };