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

[Mathieu Desnoyers]

On 2026-02-26 10:55, Jeff Layton wrote:
> 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.

Changing this type first without changing its associated format strings
breaks git bisect.

One alternative would be to introduce something like the PRIu64 macro
but for printing inode values. This would allow gradually introducing
the change without breaking the world as you do so.

Thanks,

Mathieu

--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com