[PATCH 4.15 53/53] ovl: set lower layer st_dev only if setting lower st_ino

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Amir Goldstein <amir73il@gmail.com>

commit 9f99e50d460ac7fd5f6c9b97aad0088c28c8656d upstream.

For broken hardlinks, we do not return lower st_ino, so we should
also not return lower pseudo st_dev.

Fixes: a0c5ad307ac0 ("ovl: relax same fs constraint for constant st_ino")
Cc: <stable@vger.kernel.org> #v4.15
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/overlayfs/inode.c |    7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -110,13 +110,10 @@ int ovl_getattr(const struct path *path,
 			 * that the upper hardlink is not broken.
 			 */
 			if (is_dir || lowerstat.nlink == 1 ||
-			    ovl_test_flag(OVL_INDEX, d_inode(dentry)))
+			    ovl_test_flag(OVL_INDEX, d_inode(dentry))) {
 				stat->ino = lowerstat.ino;
-
-			if (samefs)
-				WARN_ON_ONCE(stat->dev != lowerstat.dev);
-			else
 				stat->dev = ovl_get_pseudo_dev(dentry);
+			}
 		}
 		if (samefs) {
 			/*