From: Al Viro <viro@ZenIV.linux.org.uk>
To: Christoph Hellwig <hch@infradead.org>
Cc: Alessio Igor Bogani <abogani@texware.it>,
Jonathan Corbet <corbet@lwn.net>,
Fr??d??ric Weisbecker <fweisbec@gmail.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
LKML <linux-kernel@vger.kernel.org>,
LFSDEV <linux-fsdevel@vger.kernel.org>,
Matthew Wilcox <matthew@wil.cx>, Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH vfs-2.6:for-next] vfs: remount_fs BKL pushdown
Date: Wed, 6 May 2009 07:48:27 +0100 [thread overview]
Message-ID: <20090506064827.GR8633@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20090506062630.GA28560@infradead.org>
On Wed, May 06, 2009 at 02:26:30AM -0400, Christoph Hellwig wrote:
> On Wed, May 06, 2009 at 04:51:38AM +0100, Al Viro wrote:
> > Actually, I'm not sure that you are right. Especially if we go for your
> > "always hold s_umount for sync_filesystem()"; in that case we are guaranteed
> > that we'll have an exclusion between ->write_super() and that sucker, so
> > there's no reason to push it down into filesystems that do not use lock_super()
>
> The interesting cases are locking against internal s_lock which at least
> extN needs or ->write_super. And I'd really be rather safe than sorry
> and audit individual filesystems than introducing bug in an obscure one.
write_super() can *not* get contention against remount. That's the point.
And other that write_super, we have very few filesystems that even mention
lock_super() anywhere. Yes, ext3 and ext4. Also fat, sysv, ufs and hpfs.
That's it. Compare with the number of suckers that have write_super()
and especially remount_fs()...
prev parent reply other threads:[~2009-05-06 6:48 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-25 8:09 [PATCH vfs-2.6:for-next] vfs: remount_fs BKL pushdown Alessio Igor Bogani
2009-04-25 8:23 ` Christoph Hellwig
2009-05-05 13:37 ` Christoph Hellwig
2009-05-05 19:39 ` Alessio Igor Bogani
2009-05-05 19:39 ` Alessio Igor Bogani
2009-05-05 20:43 ` Christoph Hellwig
2009-05-06 3:51 ` Al Viro
2009-05-06 6:26 ` Christoph Hellwig
2009-05-06 6:48 ` Al Viro [this message]
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