From: Jan Kara <jack@suse.cz>
To: Mingming Cao <cmm@us.ibm.com>
Cc: akpm@linux-foundation.org, pbadari@us.ibm.com,
linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: Possible race between direct IO and JBD?
Date: Mon, 28 Apr 2008 14:26:26 +0200 [thread overview]
Message-ID: <20080428122626.GC17054@duck.suse.cz> (raw)
In-Reply-To: <1209166706.6040.20.camel@localhost.localdomain>
Hi,
On Fri 25-04-08 16:38:23, Mingming Cao wrote:
> While looking at a bug related to direct IO returns to EIO, after
> looking at the code, I found there is a window that
> try_to_free_buffers() from direct IO could race with JBD, which holds
> the reference to the data buffers before journal_commit_transaction()
> ensures the data buffers has reached to the disk.
>
> A little more detail: to prepare for direct IO, generic_file_direct_IO()
> calls invalidate_inode_pages2_range() to invalidate the pages in the
> cache before performaning direct IO. invalidate_inode_pages2_range()
> tries to free the buffers via try_to free_buffers(), but sometimes it
> can't, due to the buffers is possible still on some transaction's
> t_sync_datalist or t_locked_list waiting for
> journal_commit_transaction() to process it.
>
> Currently Direct IO simply returns EIO if try_to_free_buffers() finds
> the buffer is busy, as it has no clue that JBD is referencing it.
>
> Is this a known issue and expected behavior? Any thoughts?
Are you seeing this in data=ordered mode? As Andrew pointed out we do
filemap_write_and_wait() so all the relevant data buffers of the inode
should be already on disk. In __journal_try_to_free_buffer() we check
whether the buffer is already-written-out data buffer and unfile and free
it in that case. It shouldn't happen that a data buffer has
b_next_transaction set so really the only idea why try_to_free_buffers()
could fail is that somebody manages to write to a page via mmap before
invalidate_inode_pages2_range() gets to it. Under which kind of load do you
observe the problem? Do you know exactly because of which condition does
journal_try_to_free_buffers() fail?
Honza
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR
next prev parent reply other threads:[~2008-04-28 12:26 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-06 17:42 [RFC] JBD ordered mode rewrite Jan Kara
2008-03-06 19:05 ` Josef Bacik
2008-03-10 16:30 ` Jan Kara
2008-03-06 23:53 ` Andrew Morton
2008-03-10 17:38 ` Jan Kara
2008-03-07 1:34 ` Mark Fasheh
2008-03-10 18:00 ` Jan Kara
2008-03-07 10:55 ` Mingming Cao
2008-03-10 18:29 ` Jan Kara
2008-03-07 23:52 ` Andreas Dilger
2008-03-08 0:08 ` Mingming Cao
2008-03-08 12:14 ` Christoph Hellwig
2008-03-10 19:54 ` Jan Kara
2008-03-10 21:37 ` Andreas Dilger
2008-04-25 23:38 ` Possible race between direct IO and JBD? Mingming Cao
2008-04-26 10:41 ` Andrew Morton
2008-04-28 12:26 ` Jan Kara [this message]
2008-04-28 17:11 ` Badari Pulavarty
2008-04-28 18:09 ` Jan Kara
2008-04-28 19:09 ` Mingming Cao
2008-04-29 12:43 ` Jan Kara
2008-04-29 17:49 ` Mingming Cao
2008-05-01 15:16 ` [PATCH] jbd_commit_transaction() races with journal_try_to_drop_buffers() causing DIO failures Badari Pulavarty
2008-05-01 22:08 ` Mingming Cao
2008-05-05 17:06 ` Jan Kara
2008-05-05 17:53 ` Mingming Cao
2008-05-06 0:10 ` Badari Pulavarty
2008-05-09 22:27 ` Mingming Cao
2008-05-12 15:54 ` Jan Kara
2008-05-12 19:23 ` Mingming Cao
2008-05-13 14:20 ` Jan Kara
2008-05-13 0:39 ` Mingming Cao
2008-05-13 14:54 ` Jan Kara
2008-05-13 16:37 ` Mingming Cao
2008-05-13 22:23 ` Mingming Cao
2008-05-14 17:08 ` Jan Kara
2008-05-14 17:41 ` Mingming Cao
2008-05-14 18:14 ` Jan Kara
2008-05-16 14:13 ` Mingming Cao
2008-05-16 14:14 ` [PATCH] Fix DIO EIO error caused by race between jbd_commit_transaction() and journal_try_to_drop_buffers() Mingming Cao
2008-05-16 15:01 ` Josef Bacik
2008-05-16 17:11 ` Mingming Cao
2008-05-16 17:17 ` Badari Pulavarty
2008-05-16 17:30 ` Mingming Cao
2008-05-16 17:12 ` Badari Pulavarty
2008-05-16 21:01 ` [PATCH] JBD: Fix DIO EIO error caused by race between free buffer and commit trasanction Mingming Cao
2008-05-18 22:37 ` Jan Kara
2008-05-19 19:59 ` Mingming Cao
2008-05-19 20:25 ` Andrew Morton
2008-05-19 22:07 ` Mingming Cao
2008-05-20 9:30 ` Jens Axboe
2008-05-20 17:47 ` Mingming Cao
2008-05-20 18:02 ` [PATCH-v2] JBD: Fix " Mingming Cao
2008-05-20 23:53 ` Jan Kara
2008-05-21 17:14 ` Mingming
2008-05-24 22:44 ` Jan Kara
2008-05-28 18:18 ` Mingming Cao
2008-05-28 18:55 ` Jan Kara
2008-05-29 0:15 ` Mingming Cao
2008-05-29 0:16 ` [PATCH][take 5] " Mingming Cao
2008-05-29 0:18 ` [PATCH][take 5] JBD2: " Mingming Cao
2008-05-30 6:24 ` Aneesh Kumar K.V
2008-05-30 15:17 ` Mingming Cao
2008-05-21 23:38 ` [PATCH 1/2][TAKE3] JBD: " Mingming
2008-05-22 5:57 ` Andrew Morton
2008-05-21 23:39 ` [PATCH 2/2][TAKE3] JBD2: " Mingming
2008-05-20 18:03 ` [PATCH -v2] JBD2: Fix race between journal " Mingming Cao
2008-05-16 21:01 ` [PATCH] JBD2: Fix DIO EIO error caused by race between " Mingming Cao
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