ocfs2: fix d_splice_alias() return code checking

d_splice_alias() can return a valid dentry, NULL or an ERR_PTR.
Currently the code checks not for ERR_PTR and will cuase an oops in
ocfs2_dentry_attach_lock().  Fix this by using IS_ERR_OR_NULL().
Signed-off-by: NRichard Weinberger <richard@nod.at>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

fs/ocfs2/namei.c

@@ -158,7 +158,7 @@ static struct dentry *ocfs2_lookup(struct inode *dir, struct dentry *dentry,
 		 * NOTE: This dentry already has ->d_op set from
 		 * ocfs2_get_parent() and ocfs2_get_dentry()
 		 */
-		if (ret)
+		if (!IS_ERR_OR_NULL(ret))
 			dentry = ret;
 
 		status = ocfs2_dentry_attach_lock(dentry, inode,