[PATCH 02/61] vfs: change i_ino from unsigned long to u64

Jeff Layton
2026-02-26T15:56:42Z

Change the type of i_ino in struct inode from unsigned long to u64.

On 64-bit architectures, unsigned long is already 64 bits, so this is
effectively a type alias change with no runtime impact. On 32-bit
architectures, this widens i_ino from 32 to 64 bits, allowing
filesystems like NFS, CIFS, XFS, Ceph, and FUSE to store their native
64-bit inode numbers without folding/hashing.

The VFS already handles 64-bit inode numbers in kstat.ino (u64) and
statx.stx_ino (__u64). The existing overflow checks in cp_new_stat(),
cp_old_stat(), and cp_compat_stat() handle narrowing to 32-bit st_ino
with -EOVERFLOW, so userspace ABI is preserved.

struct inode will grow by 4 bytes on 32-bit architectures.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
include/linux/fs.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index dfa1f475b1c480c503ab6f00e891aa9b051607fa..097443bf12e289c347651e5f3da5b67eb6b53121 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -783,7 +783,7 @@ struct inode {
#endif

/* Stat data, not accessed from path walking */
- unsigned long i_ino;
+ u64 i_ino;
/*
* Filesystems may only read i_nlink directly. They shall use the
* following functions for modification:

--
2.53.0