From: "J. Bruce Fields" <bfields@fieldses.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>
Subject: Re: [PATCH] xfs: use a unique and persistent value for f_fsid
Date: Fri, 26 Mar 2021 15:15:54 -0400 [thread overview]
Message-ID: <20210326191554.GB13139@fieldses.org> (raw)
In-Reply-To: <CAOQ4uxjFMPNgR-aCqZt3FD90XtBVFZncdgNc4RdOCbsxukkyYQ@mail.gmail.com>
On Tue, Mar 23, 2021 at 06:50:44AM +0200, Amir Goldstein wrote:
> On Tue, Mar 23, 2021 at 1:03 AM Dave Chinner <david@fromorbit.com> wrote:
> > should be using something common across all filesystems from the
> > linux superblock, not deep dark internal filesystem magic. The
> > export interfaces that generate VFS (and NFS) filehandles already
> > have a persistent fsid associated with them, which may in fact be
> > the filesystem UUID in it's entirety.
> >
>
> Yes, nfsd is using dark internal and AFAIK undocumnetd magic to
> pick that identifier (Bruce, am I wrong?).
Sorry, I kept putting off catching up with this thread and only now
noticed the question.
It's actually done mostly in userspace (rpc.mountd), so "dark internal"
might not be fair, but it is rather complicated. There are several
options (UUID, device number, number provided by the user with fsid=
option), and I don't recall the logic behind which we use when.
I don't *think* we have good comprehensive documentation of it anywhere.
I wish we did. It'd take a little time to put together. Starting
points would be linux/fs/nfsd/nfsfh.c and
nfs-utils/support/export/cache.c.
--b.
next prev parent reply other threads:[~2021-03-26 19:16 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
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 [this message]
2021-03-27 9:06 ` Amir Goldstein
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