Re: [PATCH] locks: export device name

Andrew Morton
2012-02-14T00:34:29Z

On Fri, 10 Feb 2012 22:06:07 +0100
Davidlohr Bueso <dave@gnu.org> wrote:

> From: Davidlohr Bueso <dave@gnu.org>
>
> The lslk(8) program has not been maintained for over a decade and has recently been rewritten as lslocks(8).
> It will be available for the next 2.22 release, in a couple of months. This is a good opportunity to delete
> that nasty WE_CAN_BREAK_LSLK_NOW and start exporting the device name instead of the maj:min numbers.
>
> For backward compatibility the new version can be in charge of checking older kernel versions and parsing the old
> output if necessary.
>
> ...
>
> --- a/fs/locks.c
> +++ b/fs/locks.c
> @@ -2199,15 +2199,8 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl,
> : (fl->fl_type & F_WRLCK) ? "WRITE" : "READ ");
> }
> if (inode) {
> -#ifdef WE_CAN_BREAK_LSLK_NOW
> seq_printf(f, "%d %s:%ld ", fl_pid,
> inode->i_sb->s_id, inode->i_ino);
> -#else
> - /* userspace relies on this representation of dev_t ;-( */
> - seq_printf(f, "%d %02x:%02x:%ld ", fl_pid,
> - MAJOR(inode->i_sb->s_dev),
> - MINOR(inode->i_sb->s_dev), inode->i_ino);
> -#endif
> } else {
> seq_printf(f, "%d <none>:0 ", fl_pid);
> }

I don't get it. This is an immediate and non-back-compatible change to
the format of /proc/locks. The only way this can avoid breaking things
is if there are no programs or scripts in use by anyone which use
this field. What am I missing here?