From: Andreas Dilger <adilger@sun.com>
To: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Cc: coly.li@suse.de, linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Roman Zippel <zippel@linux-m68k.org>,
"Sergey S. Kostyliov" <rathamahata@php4.ru>,
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>,
Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>,
Bob Copeland <me@bobcopeland.com>, Anders Larsen <al@alarsen.net>,
reiserfs-devel@vger.kernel.org,
Phillip Lougher <phillip@lougher.demon.co.uk>,
Christoph Hellwig <hch@infradead.org>,
Evgeniy Dushistov <dushistov@mail.ru>, Jan Kara <jack@suse.cz>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH 0/20] return f_fsid for statfs(2)
Date: Mon, 19 Jan 2009 21:13:49 -0700 [thread overview]
Message-ID: <20090120041349.GL3286@webber.adilger.int> (raw)
In-Reply-To: <1232419149.19468.3.camel@norville.austin.ibm.com>
On Jan 19, 2009 20:39 -0600, Dave Kleikamp wrote:
> On Tue, 2009-01-20 at 07:36 +0800, Andreas Dilger wrote:
> > The whole point of fsid (for NFS) is that this identifies the filesystem
> > over reboot, even if the block device ID changes, or if the filesystem
> > doesn't have a block device at all (e.g. cluster filesystem).
>
> I guess that just demonstrates how little I know about what the fsid is
> about. Would it be preferable for file systems that have a uuid to use
> that instead? Of course anything is an improvement over zeroes.
Yes, that is what the ext* patches do - fold the 128-bit UUID into a 64-bit
fsid so that it is constant across reboots. The chance of UUID collision
is about 1/2^32 due to birthday paradox, which is fairly low, and in case
this happens one of the filesystem UUIDs can be regenerated.
Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.
next prev parent reply other threads:[~2009-01-20 4:13 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-19 17:30 [PATCH 0/20] return f_fsid for statfs(2) Coly Li
2009-01-19 19:28 ` Dave Kleikamp
2009-01-19 23:36 ` Andreas Dilger
2009-01-20 2:39 ` Dave Kleikamp
2009-01-20 4:13 ` Andreas Dilger [this message]
2009-01-20 4:30 ` Coly Li
2009-01-20 4:44 ` Andreas Dilger
2009-01-20 7:03 ` Coly Li
2009-01-20 18:48 ` Jamie Lokier
2009-01-22 19:36 ` Coly Li
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20090120041349.GL3286@webber.adilger.int \
--to=adilger@sun.com \
--cc=akpm@linux-foundation.org \
--cc=al@alarsen.net \
--cc=coly.li@suse.de \
--cc=dushistov@mail.ru \
--cc=hch@infradead.org \
--cc=hirofumi@mail.parknet.co.jp \
--cc=jack@suse.cz \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=me@bobcopeland.com \
--cc=mikulas@artax.karlin.mff.cuni.cz \
--cc=phillip@lougher.demon.co.uk \
--cc=rathamahata@php4.ru \
--cc=reiserfs-devel@vger.kernel.org \
--cc=shaggy@linux.vnet.ibm.com \
--cc=zippel@linux-m68k.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.