[PATCH 1/8] quota: Allow to pass mount path to quotactl

[Christoph Hellwig]

On Wed, Jan 27, 2021 at 03:46:46PM +0100, Jan Kara wrote:
> In a puristic world they'd be 9 different syscalls ... or somewhat less
> because Q_GETNEXTQUOTA is a superset of Q_GETQUOTA, we could drop Q_SYNC
> and Q_GETFMT because they have dubious value these days so we'd be left
> with 6. I don't have a strong opinion whether 6 syscalls are worth the
> cleanliness or whether we should go with just one new quotactl_path()
> syscall. I've CCed linux-api in case other people have opinion.
> 
> Anyway, even if we go with single quotactl_path() syscall we should remove
> the duplication between VFS and XFS quotactls when we are creating a new
> syscall. Thoughts?

I thunk the multiplexer is just fine.  We don't really need Q_SYNC
for a new syscall.  For XFS vs classic VFS quota we probably don't
need to duplicate the two data structure, but we need to make sure we
catch the superset of the information if we want to disable the old
ones.

So I suspect just supporting evrything excpt for the global Q_SYNC
and reusing do_quotactl as-is is the most maintainable and easiest
to understand way forward.