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From:   Miklos Szeredi <miklos@szeredi.hu>
Date:   Sat, 7 Mar 2020 21:48:35 +0100
Message-ID: <CAJfpegvOi0ZPEW4Aq8N8SPDwiEw8Tgzo-ngf30WNmHXBdfHnqA@mail.gmail.com>
Subject: Re: [PATCH 00/17] VFS: Filesystem information and notifications [ver #17]
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Ian Kent <raven@themaw.net>, David Howells <dhowells@redhat.com>,
        Christian Brauner <christian.brauner@ubuntu.com>,
        James Bottomley <James.Bottomley@hansenpartnership.com>,
        Steven Whitehouse <swhiteho@redhat.com>,
        Miklos Szeredi <mszeredi@redhat.com>,
        viro <viro@zeniv.linux.org.uk>,
        Christian Brauner <christian@brauner.io>,
        Jann Horn <jannh@google.com>,
        "Darrick J. Wong" <darrick.wong@oracle.com>,
        Linux API <linux-api@vger.kernel.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        lkml <linux-kernel@vger.kernel.org>
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On Sat, Mar 7, 2020 at 10:48 AM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Fri, Mar 06, 2020 at 05:25:49PM +0100, Miklos Szeredi wrote:
> > On Tue, Mar 03, 2020 at 08:46:09AM +0100, Miklos Szeredi wrote:
> > >
> > > I'm doing a patch.   Let's see how it fares in the face of all these
> > > preconceptions.
> >
> > Here's a first cut.  Doesn't yet have superblock info, just mount info.
> > Probably has rough edges, but appears to work.
> >
> > I started with sysfs, then kernfs, then went with a custom filesystem, because
> > neither could do what I wanted.
>
> Hm, what is wrong with kernfs that prevented you from using it here?
> Just complexity or something else?

I wanted to have a single instance covering all the namespaces, with
just a filtered view depending on which namespace the task is looking
at it.

Having a kernfs_node for each attribute is also rather heavy compared
to the size of struct mount.

Thanks,
Miklos