[PATCH 5.5 130/367] ovl: fix wrong WARN_ON() in ovl_cache_update_ino()

Greg Kroah-Hartman
2020-02-10T12:44:00Z

From: Amir Goldstein <amir73il@gmail.com>

commit 4c37e71b713ecffe81f8e6273c6835e54306d412 upstream.

The WARN_ON() that child entry is always on overlay st_dev became wrong
when we allowed this function to update d_ino in non-samefs setup with xino
enabled.

It is not true in case of xino bits overflow on a non-dir inode. Leave the
WARN_ON() only for directories, where assertion is still true.

Fixes: adbf4f7ea834 ("ovl: consistent d_ino for non-samefs with xino")
Cc: <stable@vger.kernel.org> # v4.17+
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/overlayfs/readdir.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -504,7 +504,13 @@ get:
if (err)
goto fail;

- WARN_ON_ONCE(dir->d_sb->s_dev != stat.dev);
+ /*
+ * Directory inode is always on overlay st_dev.
+ * Non-dir with ovl_same_dev() could be on pseudo st_dev in case
+ * of xino bits overflow.
+ */
+ WARN_ON_ONCE(S_ISDIR(stat.mode) &&
+ dir->d_sb->s_dev != stat.dev);
ino = stat.ino;
} else if (xinobits && !OVL_TYPE_UPPER(type)) {
ino = ovl_remap_lower_ino(ino, xinobits,