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From:   Miklos Szeredi <miklos@szeredi.hu>
Date:   Wed, 19 Jun 2019 08:33:40 +0200
Message-ID: <CAJfpegtXp0bQRFGaZia_MGmFGFjKG5XoCnDCy=onmsWBJGHMHw@mail.gmail.com>
Subject: Re: [PATCH 04/25] vfs: Implement parameter value retrieval with
 fsinfo() [ver #13]
To:     David Howells <dhowells@redhat.com>
Cc:     Al Viro <viro@zeniv.linux.org.uk>, Ian Kent <raven@themaw.net>,
        Linux API <linux-api@vger.kernel.org>,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        Miklos Szeredi <mszeredi@redhat.com>
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On Wed, Jun 19, 2019 at 12:34 AM David Howells <dhowells@redhat.com> wrote:

> > Same goes for vfs_parse_sb_flag() btw.   It should be moved into each
> > filesystem's ->parse_param() and not be a mandatory thing.
>
> I disagree.  Every filesystem *must* be able to accept these standard flags,
> even if it then ignores them.

"posixacl" is not a standard flag.  It never was accepted by mount(8)
so I don't see where you got that from.

Can you explain why you think "mand", "sync", "dirsync", "lazytime"
should be accepted by a filesystem such as proc?  The argument that it
breaks userspace is BS, because this is a new interface, hence by
definition we cannot break old userspace.  If mount(8) wants to use
the new API and there really is breakage if these options are rejected
(which I doubt) then it can easily work around that by ignoring them
itself.

Also why should "rw" not be rejected for filesystems which are
read-only by definition, such as iso9660?

Thanks,
Miklos