Re: [PATCH v3 0/2] quota: Add mountpath based quota support

From: Sascha Hauer <s.hauer@pengutronix.de>
To: Jan Kara <jack@suse.cz>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-api@vger.kernel.org, Christoph Hellwig <hch@infradead.org>,
	kernel@pengutronix.de, Jan Kara <jack@suse.com>,
	Richard Weinberger <richard@nod.at>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Christian Brauner <christian.brauner@ubuntu.com>
Subject: Re: [PATCH v3 0/2] quota: Add mountpath based quota support
Date: Wed, 12 May 2021 17:03:46 +0200	[thread overview]
Message-ID: <20210512150346.GQ19819@pengutronix.de> (raw)
In-Reply-To: <20210512110149.GA31495@quack2.suse.cz>

On Wed, May 12, 2021 at 01:01:49PM +0200, Jan Kara wrote:
> Added a few more CCs.
> 
> On Tue 16-03-21 12:29:16, Jan Kara wrote:
> > On Thu 04-03-21 13:35:38, Sascha Hauer wrote:
> > > Current quotactl syscall uses a path to a block device to specify the
> > > filesystem to work on which makes it unsuitable for filesystems that
> > > do not have a block device. This series adds a new syscall quotactl_path()
> > > which replaces the path to the block device with a mountpath, but otherwise
> > > behaves like original quotactl.
> > > 
> > > This is done to add quota support to UBIFS. UBIFS quota support has been
> > > posted several times with different approaches to put the mountpath into
> > > the existing quotactl() syscall until it has been suggested to make it a
> > > new syscall instead, so here it is.
> > > 
> > > I'm not posting the full UBIFS quota series here as it remains unchanged
> > > and I'd like to get feedback to the new syscall first. For those interested
> > > the most recent series can be found here: https://lwn.net/Articles/810463/
> > 
> > Thanks. I've merged the two patches into my tree and will push them to
> > Linus for the next merge window.
> 
> So there are some people at LWN whining that quotactl_path() has no dirfd
> and flags arguments for specifying the target. Somewhat late in the game
> but since there's no major release with the syscall and no userspace using
> it, I think we could still change that. What do you think? What they
> suggest does make some sense. But then, rather then supporting API for
> million-and-one ways in which I may wish to lookup a fs object, won't it be
> better to just pass 'fd' in the new syscall (it may well be just O_PATH fd
> AFAICT) and be done with that?

This sounds like a much cleaner interface to me. If we agree on this I
wouldn't mind spinning this patch for another few rounds.

Sascha

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