[PATCH 6.18 216/309] ovl: fix wrong detection of 32bit inode numbers

Greg Kroah-Hartman
2026-03-31T17:05:55Z

From: Amir Goldstein <amir73il@gmail.com>

commit 53a7c171e9dd833f0a96b545adcb89bd57387239 upstream.

The implicit FILEID_INO32_GEN encoder was changed to be explicit,
so we need to fix the detection.

When mounting overlayfs with upperdir and lowerdir on different ext4
filesystems, the expected kmsg log is:

overlayfs: "xino" feature enabled using 32 upper inode bits.

But instead, since the regressing commit, the kmsg log was:

overlayfs: "xino" feature enabled using 2 upper inode bits.

Fixes: e21fc2038c1b9 ("exportfs: make ->encode_fh() a mandatory method for NFS export")
Cc: stable@vger.kernel.org # v6.7+
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/overlayfs/util.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -90,7 +90,10 @@ int ovl_can_decode_fh(struct super_block
if (!exportfs_can_decode_fh(sb->s_export_op))
return 0;

- return sb->s_export_op->encode_fh ? -1 : FILEID_INO32_GEN;
+ if (sb->s_export_op->encode_fh == generic_encode_ino32_fh)
+ return FILEID_INO32_GEN;
+
+ return -1;
}

struct dentry *ovl_indexdir(struct super_block *sb)