linux-kernel - Re: [PATCH 1/2] quota: Add mountpath based quota support

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Message-ID: <20210212104114.GV19070@quack2.suse.cz>
Date:   Fri, 12 Feb 2021 11:41:14 +0100
From:   Jan Kara <jack@...e.cz>
To:     Sascha Hauer <s.hauer@...gutronix.de>
Cc:     Jan Kara <jack@...e.cz>, Richard Weinberger <richard@....at>,
        linux-kernel@...r.kernel.org,
        Christoph Hellwig <hch@...radead.org>, kernel@...gutronix.de,
        Jan Kara <jack@...e.com>, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH 1/2] quota: Add mountpath based quota support

On Fri 12-02-21 11:29:00, Sascha Hauer wrote:
> On Fri, Feb 12, 2021 at 11:05:05AM +0100, Jan Kara wrote:
> > On Fri 12-02-21 09:38:35, Sascha Hauer wrote:
> > > On Thu, Feb 11, 2021 at 03:38:13PM +0000, Christoph Hellwig wrote:
> > > > > +	if (!mountpoint)
> > > > > +		return -ENODEV;
> > > > > +
> > > > > +	ret = user_path_at(AT_FDCWD, mountpoint,
> > > > > +			     LOOKUP_FOLLOW | LOOKUP_AUTOMOUNT, &mountpath);
> > > > 
> > > > user_path_at handles an empty path, although you'll get EFAULT instead.
> > > > Do we care about the -ENODEV here?
> > > 
> > > The quotactl manpage documents EFAULT as error code for invalid addr or
> > > special argument, so we really should return -EFAULT here.
> > > 
> > > Existing quotactl gets this wrong as well:
> > > 
> > > 	if (!special) {
> > > 		if (cmds == Q_SYNC)
> > > 			return quota_sync_all(type);
> > > 		return -ENODEV;
> > > 	}
> > > 
> > > Should we fix this or is there userspace code that is confused by a changed
> > > return value?
> > 
> > I'd leave the original quotactl(2) as is. There's no strong reason to risk
> > breaking some userspace. For the new syscall, I agree we can just
> > standardize the return value, there ENODEV makes even less sense since
> > there's no device in that call.
> 
> Ok, will do. Who can pick this series up? Anyone else I need to Cc next
> round?

I guess I can pick up both kernel patches (the manpage patch needs to be
submitted to the manpage list) but please CC linux-api@...r as well so that
interested people are aware of the new syscall.

								Honza
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR