Re: [PATCH v1] man/man2/quotactl.2: tfix

Hi Alejandro!

On Mon 18-05-26 14:51:45, Alejandro Colomar wrote:
> On 2026-05-18T12:20:50+0200, Jan Kara wrote:
> > On Sat 16-05-26 19:12:08, Alejandro Colomar wrote:
> > > It seems most likely that this was a typo, and that Q_XQUOTAON was
> > > meant.
> > > 
> > > Fixes: 1eeddf25 (2010-06-16; "quotactl.2: Major updates")
> > > Cc: Jan Kara <[email protected]>
> > > Cc: Petr Gajdos <[email protected]>
> > > Cc: Jan Blunck <[email protected]>
> > > Signed-off-by: Alejandro Colomar <[email protected]>
> > 
> > Right. Thanks for the fix. Feel free to add:
> 
> I have more questions about quotactl(2).  In the operations that ignore
> the 'id' argument, am I right to assume that QCMD() is unnecessary?  My
> assumption is because if there's no user or group ID to be used, it also
> doesn't make sense to specify whether we want to affect a user or a
> group.
> 
> So, for example, Q_QUOTAOFF would have the following synopsis:
> 
> 	int quotactl(Q_QUOTAOFF, const char *_Nullable special, 0, NULL);
> 
> While Q_QUOTAON would have the following one:
> 
> 	int quotactl(QCMD(Q_QUOTAON, type), const char *_Nullable special,
> 		     int fmt, caddr_t quota_path);
> 
> Is that correct?

No, QCMD() is always required. For example for Q_QUOTAOFF you still need to
tell whether you want to disable user or group quotas. And even if the type
would not matter for some quotactl, QCMD still does a mangling to the
passed arguments that is expected by the kernel (QCMD is ((cmd) <<
SUBCMDSHIFT) | ((type) & SUBCMDMASK)).

> Also, I wonder why caddr_t was used at all, instead of void*.  It seems
> to unnecessarily require a cast, which could have been avoided with
> void*.  In quotactl_fd(), since we need to use syscall(2), which is
> variadic, I'll document the correct pointer types, instead of caddr_t*.

For this I don't have a good answer. It was like that for ages... I guess
you can ask glibc guys - the kernel uses void * but glibc uses caddr_t.

								Honza
-- 
Jan Kara <[email protected]>
SUSE Labs, CR