From: Tao Ma <tao.ma@oracle.com>
To: Tejun Heo <tj@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 02/41] block/loop: queue ordered mode should be DRAIN_FLUSH
Date: Sun, 12 Sep 2010 19:55:47 +0800 [thread overview]
Message-ID: <4C8CBFC3.8060706@oracle.com> (raw)
In-Reply-To: <4C8CBC50.1070400@kernel.org>
On 09/12/2010 07:41 PM, Tejun Heo wrote:
> Hello,
>
> On 09/12/2010 10:38 AM, Tao Ma wrote:
>> According to Documentation/block/barrier.txt,
>> QUEUE_ORDERED_DRAIN
>> Requests are ordered by draining the request queue and cache
>> flushing isn't needed.
>>
>> Sequence: drain => barrier
>>
>> QUEUE_ORDERED_DRAIN_FLUSH
>> Requests are ordered by draining the request queue and both
>> pre-barrier and post-barrier cache flushings are needed.
>>
>> Sequence: drain => preflush => barrier => postflush
>>
>> And for loop device, it call fsync in barrier request. See do_bio_filebacked in drivers/block/loop.c
>> bool barrier = !!(bio->bi_rw& REQ_HARDBARRIER);
>> struct file *file = lo->lo_backing_file;
>>
>> if (barrier) {
>> if (unlikely(!file->f_op->fsync)) {
>> ret = -EOPNOTSUPP;
>> goto out;
>> }
>>
>> ret = vfs_fsync(file, 0);
>> if (unlikely(ret)) {
>> ret = -EIO;
>> goto out;
>> }
>> }
>>
>> So actually the sync is done in barrier and no extra flush is needed?
>> Or Do I misread the rules in barrier.txt?
>
> Hmmm... maybe the doc was a bit confusing. Any device which has
> writeback cache should have FLUSH in the queue ordered configuration.
> The loop device used vfs_fsync() for cache flushing and didn't support
> ordered sequence. As such, it should use draining for request
> ordering and suports FLUSH, so the mode to use is DRAIN_FLUSH.
oh, thanks for the explanation.
Regards,
Tao
next prev parent reply other threads:[~2010-09-12 11:56 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-03 10:29 [PATCHSET #upstream] block, fs: replace HARDBARRIER with FLUSH/FUA, take#2 Tejun Heo
2010-09-03 10:29 ` [PATCH 01/41] ide: remove unnecessary blk_queue_flushing() test in do_ide_request() Tejun Heo
2010-09-03 10:29 ` [PATCH 02/41] block/loop: queue ordered mode should be DRAIN_FLUSH Tejun Heo
2010-09-12 8:38 ` Tao Ma
2010-09-12 11:41 ` Tejun Heo
2010-09-12 11:55 ` Tao Ma [this message]
2010-09-03 10:29 ` [PATCH 03/41] block: kill QUEUE_ORDERED_BY_TAG Tejun Heo
2010-09-03 10:29 ` [PATCH 04/41] block: deprecate barrier and replace blk_queue_ordered() with blk_queue_flush() Tejun Heo
2010-09-03 10:29 ` [PATCH 05/41] block: remove spurious uses of REQ_HARDBARRIER Tejun Heo
2010-09-03 10:29 ` [PATCH 06/41] block: misc cleanups in barrier code Tejun Heo
2010-09-03 10:29 ` [PATCH 07/41] block: drop barrier ordering by queue draining Tejun Heo
2010-09-03 10:29 ` [PATCH 08/41] block: rename blk-barrier.c to blk-flush.c Tejun Heo
2010-09-03 10:29 ` [PATCH 09/41] block: rename barrier/ordered to flush Tejun Heo
2010-09-03 10:29 ` [PATCH 10/41] block: implement REQ_FLUSH/FUA based interface for FLUSH/FUA requests Tejun Heo
2010-09-03 10:29 ` [PATCH 11/41] block: filter flush bio's in __generic_make_request() Tejun Heo
2010-09-03 10:29 ` [PATCH 12/41] block: simplify queue_next_fseq Tejun Heo
2010-09-03 10:29 ` [PATCH 13/41] block: initialize flush request with WRITE_FLUSH instead of REQ_FLUSH Tejun Heo
2010-09-03 10:29 ` [PATCH 14/41] block: kick queue after sequencing REQ_FLUSH/FUA Tejun Heo
2010-09-03 10:29 ` [PATCH 15/41] block: make sure FSEQ_DATA request has the same rq_disk as the original Tejun Heo
2010-09-03 10:29 ` [PATCH 16/41] block: update documentation for REQ_FLUSH / REQ_FUA Tejun Heo
2010-09-03 10:29 ` [PATCH 17/41] block: use REQ_FLUSH in blkdev_issue_flush() Tejun Heo
2010-09-03 10:29 ` [PATCH 18/41] block/loop: implement REQ_FLUSH/FUA support Tejun Heo
2010-09-03 10:29 ` [PATCH 19/41] virtio_blk: drop REQ_HARDBARRIER support Tejun Heo
2010-09-03 10:29 ` [PATCH 20/41] lguest: replace VIRTIO_F_BARRIER support with VIRTIO_F_FLUSH support Tejun Heo
2010-09-03 10:29 ` [PATCH 21/41] md: implment REQ_FLUSH/FUA support Tejun Heo
2010-09-03 10:29 ` [PATCH 22/41] block: make __blk_rq_prep_clone() copy most command flags Tejun Heo
2010-09-03 10:29 ` [PATCH 23/41] dm: implement REQ_FLUSH/FUA support for bio-based dm Tejun Heo
2010-09-03 12:36 ` Mike Snitzer
2010-09-06 11:14 ` [dm-devel] " Milan Broz
2010-09-07 21:17 ` Mike Snitzer
2010-09-07 22:15 ` Mike Snitzer
2010-09-07 23:49 ` [PATCH 42/41] dm: convey that all flushes are processed as empty Mike Snitzer
2010-09-08 0:00 ` Christoph Hellwig
2010-09-08 2:04 ` [PATCH 42/41 v2] " Mike Snitzer
2010-09-08 16:09 ` Tejun Heo
2010-09-08 16:09 ` Tejun Heo
2010-09-10 18:25 ` [PATCH 23/41] dm: implement REQ_FLUSH/FUA support for bio-based dm Mikulas Patocka
2010-09-10 18:46 ` Mike Snitzer
2010-09-10 19:05 ` Mikulas Patocka
2010-09-10 19:24 ` Mike Snitzer
2010-09-10 20:06 ` Mikulas Patocka
2010-09-10 23:36 ` Tejun Heo
2010-09-11 1:46 ` Mike Snitzer
2010-09-18 17:58 ` Bill Davidsen
2010-09-18 20:42 ` [dm-devel] " Mike Snitzer
2010-09-11 12:19 ` Ric Wheeler
2010-09-13 19:01 ` Mikulas Patocka
2010-09-03 10:29 ` [PATCH 24/41] dm: implement REQ_FLUSH/FUA support for request-based dm Tejun Heo
2010-09-08 1:46 ` Kiyoshi Ueda
2010-09-03 10:29 ` [PATCH 25/41] dm: relax ordering of bio-based flush implementation Tejun Heo
2010-09-03 10:29 ` [PATCH 26/41] dm: fix locking context in queue_io() Tejun Heo
2010-09-03 10:29 ` [PATCH 27/41] block: pass gfp_mask and flags to sb_issue_discard Tejun Heo
2010-09-03 10:29 ` [PATCH 28/41] xfs: replace barriers with explicit flush / FUA usage Tejun Heo
2010-09-03 10:29 ` [PATCH 29/41] btrfs: " Tejun Heo
2010-09-03 10:29 ` [PATCH 30/41] gfs2: " Tejun Heo
2010-09-03 10:29 ` [PATCH 31/41] reiserfs: " Tejun Heo
2010-09-03 10:29 ` [PATCH 32/41] nilfs2: " Tejun Heo
2010-09-03 10:29 ` [PATCH 33/41] jbd: " Tejun Heo
2010-09-03 10:29 ` [PATCH 34/41] jbd2: Modify ASYNC_COMMIT code to not rely on queue draining on barrier Tejun Heo
2010-09-03 10:29 ` [PATCH 35/41] jbd2: replace barriers with explicit flush / FUA usage Tejun Heo
2010-09-03 10:29 ` [PATCH 36/41] ext4: do not send discards as barriers Tejun Heo
2010-09-03 10:29 ` [PATCH 37/41] fat: " Tejun Heo
2010-09-03 10:29 ` [PATCH 38/41] swap: " Tejun Heo
2010-09-03 10:29 ` [PATCH 39/41] block: remove the WRITE_BARRIER flag Tejun Heo
2010-09-03 10:29 ` [PATCH 40/41] block: remove the BLKDEV_IFL_BARRIER flag Tejun Heo
2010-09-03 10:29 ` [PATCH 41/41] block: remove the BH_Eopnotsupp flag Tejun Heo
2010-09-03 18:53 ` [PATCHSET #upstream] block, fs: replace HARDBARRIER with FLUSH/FUA, take#2 Jens Axboe
2010-09-08 16:12 ` Tejun Heo
2010-09-10 10:19 ` Jens Axboe
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