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

[Jeff Layton]

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@xxxxxxxxxx>
---
 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