[RFC PATCH v1 1/7] fs: Add inode_get_ino() and implement get_ino() for NFS

[Mickaël Salaün]

On Fri, Oct 11, 2024 at 07:54:58PM +0900, Tetsuo Handa wrote:
> On 2024/10/11 19:12, Tetsuo Handa wrote:
> > On 2024/10/11 0:26, Mickaël Salaün wrote:

> >> Another issue is on 32-bit architectures, on which ino_t is 32 bits,
> >> whereas the user space's view of an inode number can still be 64 bits.
> > 
> > Currently, ino_t is 32bits on 32-bit architectures, isn't it?
> > Why do you need to use 64bits on 32-bit architectures?
> 
> Changing from 32bits to 64bits for communicating with userspace programs
> breaks userspace programs using "ino_t" (or "unsigned long") for handling
> inode numbers, doesn't it? Attempt to change from %lu to %llu will not be
> acceptable unless the upper 32bits are guaranteed to be 0 on 32-bit
> architectures.
> 
> Since syslogd/auditd are not the only programs that parse kernel logs and
> audit logs, updating only syslogd/auditd is not sufficient. We must not break
> existing userspace programs, and thus we can't change the format string.

This might only break user space that wrongfully uses 32-bit variables
to store 64-bit values.  According to the UAPI, inode numbers should be
64 bits.