From: Christoph Hellwig <hch@infradead.org>
To: Amir Goldstein <amir73il@gmail.com>
Cc: Dave Chinner <david@fromorbit.com>,
"Darrick J . Wong" <darrick.wong@oracle.com>,
Jan Kara <jack@suse.cz>,
Christian Brauner <christian.brauner@ubuntu.com>,
linux-xfs <linux-xfs@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>,
"J. Bruce Fields" <bfields@fieldses.org>
Subject: Re: [PATCH] xfs: use a unique and persistent value for f_fsid
Date: Wed, 24 Mar 2021 07:43:18 +0000 [thread overview]
Message-ID: <20210324074318.GA2646094@infradead.org> (raw)
In-Reply-To: <CAOQ4uxhhMVQ4XE8DMU1EjaXBo-go3_pFX3CCWn=7GuUXcMW=PA@mail.gmail.com>
On Wed, Mar 24, 2021 at 08:53:25AM +0200, Amir Goldstein wrote:
> > This also means that userspace can be entirely filesystem agnostic
> > and it doesn't need to rely on parsing proc files to translate
> > ephemeral mount IDs to paths, statvfs() and hoping that f_fsid is
> > stable enough that it doesn't get the destination wrong. It also
> > means that fanotify UAPI probably no longer needs to supply a
> > f_fsid with the filehandle because it is built into the
> > filehandle....
> >
>
> That is one option. Let's call it the "bullet proof" option.
>
> Another option, let's call it the "pragmatic" options, is that you accept
> that my patch shouldn't break anything and agree to apply it.
Your patch may very well break something. Most Linux file systems do
store the dev_t in the fsid and userspace may for whatever silly
reasons depend on it.
Also trying to use the fsid for anything persistent is plain stupid,
64-bits are not enough entropy for such an identifier. You at least
need a 128-bit UUID-like identifier for that.
So I think this whole discussion is going in the wrong direction.
Is exposing a stable file system identifier useful? Yes, for many
reasons. Is repurposing the fsid for that a good idea? Hell no.
next prev parent reply other threads:[~2021-03-24 7:45 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-22 17:11 [PATCH] xfs: use a unique and persistent value for f_fsid Amir Goldstein
2021-03-22 23:03 ` Dave Chinner
2021-03-23 4:50 ` Amir Goldstein
2021-03-23 6:35 ` Darrick J. Wong
2021-03-23 6:44 ` Amir Goldstein
2021-03-23 7:26 ` Dave Chinner
2021-03-23 9:35 ` Amir Goldstein
2021-03-24 0:54 ` Dave Chinner
2021-03-24 6:53 ` Amir Goldstein
2021-03-24 7:43 ` Christoph Hellwig [this message]
2021-03-24 9:18 ` Amir Goldstein
2021-03-25 23:03 ` Dave Chinner
2021-03-25 22:53 ` Dave Chinner
2021-03-26 6:04 ` Amir Goldstein
2021-03-26 22:34 ` Theodore Ts'o
2021-03-27 9:14 ` Amir Goldstein
2021-03-26 19:15 ` J. Bruce Fields
2021-03-27 9:06 ` Amir Goldstein
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