From: Jens Axboe <jens.axboe@oracle.com>
To: Jan Kara <jack@suse.cz>
Cc: "Theodore Tso" <tytso@mit.edu>,
"Fernando Luis Vázquez Cao" <fernando@oss.ntt.co.jp>,
"Alan Cox" <alan@lxorguk.ukuu.org.uk>,
"Pavel Machek" <pavel@suse.cz>,
"kernel list" <linux-kernel@vger.kernel.org>,
sandeen@redhat.com
Subject: Re: ext2 + -osync: not as easy as it seems
Date: Wed, 14 Jan 2009 15:08:04 +0100 [thread overview]
Message-ID: <20090114140802.GC30821@kernel.dk> (raw)
In-Reply-To: <20090114140532.GC19950@duck.suse.cz>
On Wed, Jan 14 2009, Jan Kara wrote:
> > I'm not sure what you mean; if the barrier operation isn't flushing
> > all of the caches all the way out to the iron oxide, it's not going to
> > be working properly no matter where it is being called, whether it's
> > in ext4_sync_file() or in jbd2's journal_submit_commit_record().
> Well, I thought that a barrier, as an abstraction, only guarantees that
> any IO which happened before the barrier hits the iron before any IO which
> has been submitted after a barrier. This is actually enough for a
> journalling to work correctly but it's not enough for fsync() guarantees.
> But I might be wrong...
It also guarentees that when you get a completion for that barrier
write, it's on safe storage. Think of it as a flush-write-flush
operation, in the presence of write back caching.
--
Jens Axboe
next prev parent reply other threads:[~2009-01-14 14:09 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-13 13:14 ext2 + -osync: not as easy as it seems Pavel Machek
2009-01-13 13:45 ` Alan Cox
2009-01-13 14:03 ` Theodore Tso
2009-01-13 14:07 ` Jens Axboe
2009-01-13 14:26 ` [PATCH] block: Fix documentation for blkdev_issue_flush() Theodore Ts'o
2009-01-13 14:28 ` Jens Axboe
2009-01-13 14:30 ` ext2 + -osync: not as easy as it seems Jan Kara
2009-01-13 14:46 ` Theodore Tso
2009-01-14 3:37 ` Fernando Luis Vázquez Cao
2009-01-14 10:35 ` Jan Kara
2009-01-14 13:21 ` Theodore Tso
2009-01-14 14:05 ` Jan Kara
2009-01-14 14:08 ` Jens Axboe [this message]
2009-01-14 14:34 ` Theodore Tso
2009-01-14 14:43 ` Jens Axboe
2009-02-12 16:43 ` Eric Sandeen
2009-02-16 12:09 ` Jens Axboe
2009-01-14 14:12 ` Theodore Tso
2009-01-14 14:37 ` Jan Kara
2009-01-14 16:59 ` Theodore Tso
2009-01-15 12:06 ` Fernando Luis Vázquez Cao
2009-01-15 23:45 ` Jan Kara
2009-01-16 12:31 ` Fernando Luis Vázquez Cao
2009-01-16 13:55 ` ext3: call blkdev_issue_flush on fsync Fernando Luis Vázquez Cao
2009-01-16 16:30 ` Jan Kara
2009-01-17 9:47 ` Fernando Luis Vázquez Cao
2009-01-17 10:00 ` Fernando Luis Vázquez Cao
2009-01-19 12:03 ` Jan Kara
2009-01-28 9:45 ` Fernando Luis Vázquez Cao
2009-01-28 9:55 ` Jan Kara
2009-02-12 10:33 ` Fernando Luis Vázquez Cao
2009-02-12 10:35 ` vfs: Improve readability off mount flag definitins by using offsets Fernando Luis Vázquez Cao
2009-02-12 10:36 ` vfs: Add MS_FLUSHONFSYNC mount flag Fernando Luis Vázquez Cao
2009-02-12 17:13 ` Eric Sandeen
2009-02-12 17:29 ` Jeff Garzik
2009-02-14 15:36 ` Christoph Hellwig
2009-02-15 7:23 ` Fernando Luis Vázquez Cao
2009-02-15 22:54 ` Theodore Tso
2009-02-16 4:29 ` Eric Sandeen
2009-02-16 7:47 ` Fernando Luis Vázquez Cao
2009-02-12 21:23 ` Jan Kara
2009-02-12 21:30 ` Eric Sandeen
2009-02-13 1:47 ` Fernando Luis Vázquez Cao
2009-02-13 6:07 ` Eric Sandeen
2009-02-13 2:23 ` Theodore Tso
2009-02-22 14:15 ` Pavel Machek
2009-02-22 20:51 ` Eric Sandeen
2009-02-22 23:19 ` Theodore Tso
2009-02-22 23:42 ` Jeff Garzik
2009-02-22 23:46 ` Jeff Garzik
2009-02-23 1:23 ` Theodore Tso
2009-02-13 1:14 ` Fernando Luis Vázquez Cao
2009-02-13 6:20 ` Eric Sandeen
2009-02-13 10:36 ` Fernando Luis Vázquez Cao
2009-02-13 12:20 ` Dave Chinner
2009-02-13 16:29 ` Fernando Luis Vazquez Cao
2009-02-14 11:24 ` Dave Chinner
2009-02-14 13:03 ` Fernando Luis Vázquez Cao
2009-02-14 13:19 ` Fernando Luis Vázquez Cao
2009-02-15 2:48 ` Dave Chinner
2009-02-15 7:11 ` Fernando Luis Vázquez Cao
2009-02-12 10:37 ` util-linux: Add new mount options flushonfsync and noflushonfsync to mount Fernando Luis Vázquez Cao
2009-02-12 10:38 ` util-linux: Add explanation for new mount options flushonfsync and noflushonfsync to mount(8) man page Fernando Luis Vázquez Cao
2009-02-12 10:38 ` block: Add block_flush_device() Fernando Luis Vázquez Cao
2009-02-12 10:39 ` ext3: call blkdev_issue_flush on fsync Fernando Luis Vázquez Cao
2009-02-12 10:40 ` ext4: " Fernando Luis Vázquez Cao
2009-02-15 22:46 ` Theodore Tso
2009-02-16 7:09 ` Fernando Luis Vázquez Cao
2009-02-16 7:25 ` [PATCH 1/3] block: Add block_flush_device() Fernando Luis Vázquez Cao
2009-02-16 7:29 ` [2/3] ext3: call block_flush_device() on fsync Fernando Luis Vázquez Cao
2009-02-16 7:31 ` [PATCH 3/3] ext4: " Fernando Luis Vázquez Cao
2009-01-16 13:59 ` ext4: call blkdev_issue_flush " Fernando Luis Vázquez Cao
2009-01-13 14:42 ` ext2 + -osync: not as easy as it seems Pavel Machek
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