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: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <4974B8C4.3070703@suse.de>
2009-01-19 19:28 ` [PATCH 0/20] return f_fsid for statfs(2) 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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).