From: Jan Kara <jack@suse.cz>
To: Christoph Hellwig <hch@lst.de>
Cc: Jan Kara <jack@suse.cz>, axboe@kernel.dk, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 3/6] writeback: enforce s_umount locking in writeback_inodes_sb
Date: Tue, 15 Jun 2010 20:04:49 +0200 [thread overview]
Message-ID: <20100615180448.GH3347@quack.suse.cz> (raw)
In-Reply-To: <20100615175935.GA7645@lst.de>
On Tue 15-06-10 19:59:35, Christoph Hellwig wrote:
> On Tue, Jun 15, 2010 at 07:54:13PM +0200, Jan Kara wrote:
> > But this is buggy isn't it? writeback_inodes_sb() returns as soon as
> > flusher threads start submitting the IO. So we release s_umount too early -
> > flusher threads can be still writing out inodes for our work. It's exactly
> > cases like this why I don't like the work to be called "done" when flusher
> > threads actually still do it...
>
> Now that writeback_inodes_sb uses bdi_queue_work_onstack, wb_do_writeback
> doesn't signal completion until I/O is submitted. So the locking should
> be safe.
Yay, I see. But it's a bit subtle...
Honza
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR
next prev parent reply other threads:[~2010-06-15 18:05 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-08 16:14 [PATCH 0/6] writeback fixes - slow unmount and others Christoph Hellwig
2010-06-08 16:14 ` [PATCH 1/6] writeback: fix writeback completion notifications Christoph Hellwig
2010-06-08 19:50 ` Jens Axboe
2010-06-15 17:25 ` Jan Kara
2010-06-15 17:30 ` Christoph Hellwig
2010-06-08 16:14 ` [PATCH 2/6] writeback: queue work on stack in writeback_inodes_sb Christoph Hellwig
2010-06-08 19:51 ` Jens Axboe
2010-06-08 16:14 ` [PATCH 3/6] writeback: enforce s_umount locking " Christoph Hellwig
2010-06-15 17:54 ` Jan Kara
2010-06-15 17:59 ` Christoph Hellwig
2010-06-15 18:04 ` Jan Kara [this message]
2010-06-08 16:14 ` [PATCH 4/6] writeback: fix writeback_inodes_wb from writeback_inodes_sb Christoph Hellwig
2010-06-08 19:51 ` Jens Axboe
2010-06-09 12:25 ` Christoph Hellwig
2010-06-09 12:29 ` Jens Axboe
2010-06-08 16:15 ` [PATCH 5/6] writeback: simplify wakeup_flusher_threads Christoph Hellwig
2010-06-08 19:51 ` Jens Axboe
2010-06-08 16:15 ` [PATCH 6/6] writeback: simplify and split bdi_start_writeback Christoph Hellwig
2010-06-08 19:52 ` Jens Axboe
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