From: Andreas Dilger <adilger@turbolinux.com>
To: Chris Mason <mason@suse.com>
Cc: linux-kernel@vger.kernel.org, torvalds@transmeta.com,
viro@math.psu.edu, lvm-devel@sistina.com
Subject: Re: [PATCH] LVM snapshot support for reiserfs and others
Date: Thu, 9 Aug 2001 13:22:56 -0600 (MDT) [thread overview]
Message-ID: <200108091922.f79JMuqO023781@webber.adilger.int> (raw)
In-Reply-To: <190670000.997382121@tiny> "from Chris Mason at Aug 9, 2001 02:35:21 pm"
Chris Mason writes:
> Minor change in the port to 2.4.8-pre was moving the sync_supers call
> in fsync_dev_lockfs to match the changes in fsync_dev.
Good...
> + ** we call sync_supers first so that
> + ** fsync_dev_lockfs == fsync_dev for filesystems that don't provide
> + ** a lockfs call. Yes, it could be done in sync_supers_lockfs
> + ** instead, but this just makes it more explicit...
I would rather make it _less_ explicit, so that sync_supers_lockfs()
actually does the sb->s_op->write_super() call for us... Why? Because
we are already traversing the supers list at this function, and there is
no reason to waste the CPU cycles traversing this list twice. I think
the name "sync_supers_lockfs" is clear enough in showing that it is a
superset of "sync_supers" (try saying that 5 times fast ;-).
On a similar note, it is redundant that LVM calls fsync_dev() AND
fsync_dev_lockfs() if LVM_VFS_ENHANCEMENT is defined. From the above
reasoning (to only walk the supers list once) it would make sense to
call only *_lockfs() if it is available.
On an "add this patch to the kernel, please" note, support for the
write_super_lockfs() VFS method is already in ext3, so it is a good
thing, with the above caveats.
Cheers, Andreas
PS - I changed the CC list to have lvm-devel@ instead of mge@sistina.com
--
Andreas Dilger \ "If a man ate a pound of pasta and a pound of antipasto,
\ would they cancel out, leaving him still hungry?"
http://www-mddsp.enel.ucalgary.ca/People/adilger/ -- Dogbert
next prev parent reply other threads:[~2001-08-09 19:24 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-08-09 18:35 [PATCH] LVM snapshot support for reiserfs and others Chris Mason
2001-08-09 19:22 ` Andreas Dilger [this message]
2001-08-09 20:34 ` Chris Mason
2001-08-09 20:58 ` Andreas Dilger
2001-08-09 22:20 ` Chris Mason
2001-08-09 22:24 ` Alexander Viro
2001-08-09 22:42 ` Chris Mason
2001-08-09 23:26 ` Alexander Viro
2001-08-09 23:50 ` Alexander Viro
2001-08-10 19:49 ` Chris Mason
2001-08-10 20:04 ` Andrew Morton
2001-08-14 20:25 ` Andreas Dilger
2001-08-22 4:06 ` Chris Mason
[not found] <no.id>
2001-08-10 22:01 ` Alan Cox
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