From 78a1d6cdd3021715d431df617304c290036faae4 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Tue, 29 Oct 2019 13:53:29 +0000
Subject: [PATCH] ceph: add missing check in d_revalidate snapdir handling

commit 1f08529c84cfecaf1261ed9b7e17fab18541c58f upstream.

We should not play with dcache without parent locked...

Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/ceph/inode.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 8196c21d8623..acb70a6a82f0 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -1399,6 +1399,7 @@ retry_lookup:
 		dout(" final dn %p\n", dn);
 	} else if ((req->r_op == CEPH_MDS_OP_LOOKUPSNAP ||
 		    req->r_op == CEPH_MDS_OP_MKSNAP) &&
+	           test_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags) &&
 		   !test_bit(CEPH_MDS_R_ABORTED, &req->r_req_flags)) {
 		struct dentry *dn = req->r_dentry;
 		struct inode *dir = req->r_parent;