Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <YnEeuw6fd1A8usjj@miu.piliscsaba.redhat.com> <20220505123033.sgcyx7kfl4kcfcds@ws.net.home>
In-Reply-To: <20220505123033.sgcyx7kfl4kcfcds@ws.net.home>
From:   Miklos Szeredi <miklos@szeredi.hu>
Date:   Thu, 5 May 2022 15:59:45 +0200
Message-ID: <CAJfpegv2asQoevG992+1yruSrmMus57CoQ+=Cssf7O50FhyJyQ@mail.gmail.com>
Subject: Re: [RFC PATCH] getting misc stats/attributes via xattr API
To:     Karel Zak <kzak@redhat.com>
Cc:     linux-fsdevel@vger.kernel.org, Dave Chinner <david@fromorbit.com>,
        "Theodore Ts'o" <tytso@mit.edu>,
        Greg KH <gregkh@linuxfoundation.org>,
        Christian Brauner <brauner@kernel.org>,
        linux-kernel@vger.kernel.org,
        Linux API <linux-api@vger.kernel.org>,
        linux-man <linux-man@vger.kernel.org>,
        LSM <linux-security-module@vger.kernel.org>,
        Ian Kent <raven@themaw.net>,
        David Howells <dhowells@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Christian Brauner <christian@brauner.io>,
        Amir Goldstein <amir73il@gmail.com>,
        James Bottomley <James.Bottomley@hansenpartnership.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Thu, 5 May 2022 at 14:30, Karel Zak <kzak@redhat.com> wrote:

> Is there a way how to get mountinfo-like entry by mount ID for some
> sub-tree? Something like:
>
>  getfattr -etext -n ":mnt:info:21" /

Yes:

getfattr -etext -n ":mntns:21:info" /

>
> The interface has to be consistent with some notification system (I
> see your question about fsnotify/fanotify at linux-fsdevel) and mount
> ID seems better than paths due to over-mounts, etc.

Right.

If the mount notification doesn't fit into fsnotify well, the original
patch from David could be used.  I think that part was
uncontroversial.

Thanks,
Miklos