linux-ext4 - Re: [PATCH RFC] ext3 data=guarded v5

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Date:	Wed, 29 Apr 2009 13:47:31 -0600
From:	Andreas Dilger <adilger@....com>
To:	Chris Mason <chris.mason@...cle.com>
Cc:	Jan Kara <jack@...e.cz>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"Theodore Ts'o" <tytso@....edu>,
	Linux Kernel Developers List <linux-kernel@...r.kernel.org>,
	Ext4 Developers List <linux-ext4@...r.kernel.org>,
	Mike Galbraith <efault@....de>
Subject: Re: [PATCH RFC] ext3 data=guarded v5

On Apr 29, 2009  10:43 -0400, Chris Mason wrote:
> On Wed, 2009-04-29 at 10:08 -0400, Chris Mason wrote:
> > This would mean IO completion (clearing PG_writeback) would have to wait
> > on the inode mutex, which we can't quite do in O_SYNC and O_DIRECT.
> > But, what I can do is check i_nlink after the ext3_orphan_del call and
> > put the inode back on the orphan list if it has gone to zero.
> 
> Ugh, that won't work, we'll just race with link and risk an orphan that
> never gets removed.  I'll make a version of ext3_orphan_del that expects
> the super lock held and use that instead.

I looks like ext3_link() checks for i_nlink == 0 and returns -ENOENT to
avoid this race.

Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.

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