Introduce a kino_t typedef and PRIino format macro to enable a
bisect-clean transition of i_ino from unsigned long to u64.

kino_t is initially defined as unsigned long (matching the original
i_ino type), and PRIino is "l" (the format length modifier for
unsigned long). A later patch will change these to u64 and "ll"
respectively once all format strings have been updated to use PRIino.

The PRIino macro is a length modifier, not a complete format specifier.
It is used as: "%" PRIino "u" for decimal, "%" PRIino "x" for hex, etc.
This follows the pattern used by userspace PRIu64/PRIx64 macros.

Format strings using i_ino should be updated to use PRIino instead of
a hard-coded length modifier to ensure warning-free compilation on
both 32-bit and 64-bit architectures throughout the transition.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
 include/linux/fs.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 8b3dd145b25ec12b00ac1df17a952d9116b88047..e38bc5ece1f360d679a8f30b8171292f7a65c218 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -758,6 +758,9 @@ struct inode_state_flags {
 	enum inode_state_flags_enum __state;
 };
 
+typedef unsigned long	kino_t;
+#define PRIino		"l"
+
 /*
  * Keep mostly read-only and often accessed (especially for
  * the RCU path lookup and 'stat' data) fields at the beginning
@@ -783,7 +786,7 @@ struct inode {
 #endif
 
 	/* Stat data, not accessed from path walking */
-	unsigned long		i_ino;
+	kino_t			i_ino;
 	/*
 	 * Filesystems may only read i_nlink directly.  They shall use the
 	 * following functions for modification:

-- 
2.53.0

On Mon, Mar 02, 2026 at 03:23:45PM -0500, Jeff Layton wrote:
> The PRIino macro is a length modifier, not a complete format specifier.
> It is used as: "%" PRIino "u" for decimal, "%" PRIino "x" for hex, etc.
> This follows the pattern used by userspace PRIu64/PRIx64 macros.

For the record, I really hate the inttypes.h format specifiers, but I
agree that we should forward the example of the C99 spec, for better
or for worse.

That being said, the userspace PRIu64, et. al macros are complete
format specifiers, not just a length modifier.  And I think this
results in less ugly format specifiers in our kernel code.

---- cut here ---
#!/bin/sh
cat <<EOF > /tmp/blah.c
#include <inttypes.h>
#include <stdio.h>

int main(int arg, char **argv)
{
        printf("PRIu64 is %s\n", PRIu64);
        printf("PRId64 is %s\n", PRId64);
        printf("PRIx64 is %s\n", PRIx64);
        return 0;
}
EOF

clang -m32 -o /tmp/blah /tmp/blah.c
/tmp/blah
---- cut here ---

% /tmp/blah.sh
PRIu64 is llu
PRId64 is lld
PRIx64 is llx

Thanks!

						- Ted