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From: Mike Snitzer <snitzer@redhat.com>
To: Mikulas Patocka <mpatocka@redhat.com>
Cc: Tejun Heo <tj@kernel.org>,
	agk@redhat.com, jaxboe@fusionio.com,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-scsi@vger.kernel.org, linux-ide@vger.kernel.org,
	linux-raid@vger.kernel.org, dm-devel@redhat.com, hch@lst.de,
	konishi.ryusuke@lab.ntt.co.jp, James.Bottomley@suse.de,
	tytso@mit.edu, chris.mason@oracle.com, swhiteho@redhat.com,
	vst@vlnb.net, jack@suse.cz, rwheeler@redhat.com, hare@suse.de,
	neilb@suse.de, rusty@rustcorp.com.au, mst@redhat.com,
	k-ueda@ct.jp.nec.com
Subject: Re: [PATCH 23/41] dm: implement REQ_FLUSH/FUA support for bio-based dm
Date: Fri, 10 Sep 2010 14:46:52 -0400	[thread overview]
Message-ID: <20100910184652.GA24470@redhat.com> (raw)
In-Reply-To: <Pine.LNX.4.64.1009101410570.7839@hs20-bc2-1.build.redhat.com>

On Fri, Sep 10 2010 at  2:25pm -0400,
Mikulas Patocka <mpatocka@redhat.com> wrote:

> I quite disagree with the patch. It changes too many things.
> 
> What I said and what I want to see:
> 
> Take dm code as is. Treat FLUSH requests as empty barriers.
> 
> 
> So I want to see a patch that only changes:
> 
> bio_empty_barrier(bio)  ->  bio->bi_rw & REQ_FLUSH
> WRITE_BARRIER -> WRITE_FLUSH
> etc.
> 
> so that the code compiles and works.
> 
> DON'T CHANGE ANYTHING ELSE.
> 
> Requirements of flushes are subset of requirements of barriers, so if you 
> send flush and it is treated as a barrier inside DM, there's no problem. 
> DM code that I wrote only sends out zero-data barriers and already treats 
> them as flushes (it doesn't rely on ordering), so there's no problem with 
> sent requests too.
> 
> Once fluges get into kernel, I'll clean it up to allow parallel flushes 
> and requests, etc. But not before. I don't want to work on an interface 
> that is under development and may be changed.

Mikulas,

I agree that it is unfortunate that we're having to explore this level
of change to DM's flush support.  Especially given how recently your
barrier code was added.

But the work has already been done.  Rather than putting up artificial
barriers (no pun intended) it'd be great if you took the time to just
review the changes.

The patch header enumerates and describes the various changes quite
clearly.

And in fact, this first patch basically is as minimal as it gets
relative to bio-based DM's conversion to FLUSH+FUA.

Please direct your energy and talent in a positive way rather than
starting a potential flame.

Thanks,
Mike

  reply	other threads:[~2010-09-10 18:46 UTC|newest]

Thread overview: 159+ 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 ` Tejun Heo
2010-09-03 10:29 ` 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   ` Tejun Heo
2010-09-03 10:29 ` Tejun Heo
2010-09-03 10:29 ` [PATCH 02/41] block/loop: queue ordered mode should be DRAIN_FLUSH Tejun Heo
2010-09-03 10:29 ` Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-12  8:38   ` Tao Ma
2010-09-12 11:41     ` Tejun Heo
2010-09-12 11:55       ` Tao Ma
2010-09-03 10:29 ` [PATCH 03/41] block: kill QUEUE_ORDERED_BY_TAG Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29 ` 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 ` Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29 ` [PATCH 05/41] block: remove spurious uses of REQ_HARDBARRIER Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29 ` [PATCH 06/41] block: misc cleanups in barrier code Tejun Heo
2010-09-03 10:29 ` Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29 ` [PATCH 07/41] block: drop barrier ordering by queue draining Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29   ` 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   ` Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29 ` [PATCH 09/41] block: rename barrier/ordered to flush Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29 ` 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   ` Tejun Heo
2010-09-03 10:29   ` 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   ` Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29 ` [PATCH 12/41] block: simplify queue_next_fseq Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29   ` 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   ` Tejun Heo
2010-09-03 10:29   ` 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   ` Tejun Heo
2010-09-03 10:29   ` 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   ` Tejun Heo
2010-09-03 10:29   ` 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 ` Tejun Heo
2010-09-03 10:29   ` 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   ` Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29 ` [PATCH 18/41] block/loop: implement REQ_FLUSH/FUA support Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29 ` [PATCH 19/41] virtio_blk: drop REQ_HARDBARRIER support Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29   ` 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   ` Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29 ` [PATCH 21/41] md: implment REQ_FLUSH/FUA support Tejun Heo
2010-09-03 10:29 ` Tejun Heo
2010-09-03 10:29   ` 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   ` Tejun Heo
2010-09-03 10:29   ` 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 10:29   ` 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 [this message]
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
     [not found]                 ` <Pine.LNX.4.64.1009110500070.27949@hs20-bc2-1.build.redhat.com>
     [not found]                   ` <20100911132102.GA29631@redhat.com>
     [not found]                     ` <Pine.LNX.4.64.1009111251470.22177@hs20-bc2-1.build.redhat.com>
     [not found]                       ` <20100911201758.GB31324@redhat.com>
2010-09-13 18:55                         ` Mikulas Patocka
2010-09-13 20:54                           ` 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 ` Tejun Heo
2010-09-03 10:29 ` [PATCH 24/41] dm: implement REQ_FLUSH/FUA support for request-based dm Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29   ` 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   ` Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29 ` [PATCH 26/41] dm: fix locking context in queue_io() Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29   ` 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   ` Tejun Heo
2010-09-03 10:29   ` 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 ` Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29 ` [PATCH 29/41] btrfs: " Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29 ` Tejun Heo
2010-09-03 10:29 ` [PATCH 30/41] gfs2: " Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29 ` [PATCH 31/41] reiserfs: " Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29 ` Tejun Heo
2010-09-03 10:29 ` [PATCH 32/41] nilfs2: " Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29 ` [PATCH 33/41] jbd: " Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29   ` 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   ` Tejun Heo
2010-09-03 10:29   ` 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   ` Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29 ` [PATCH 36/41] ext4: do not send discards as barriers Tejun Heo
2010-09-03 10:29 ` Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29 ` [PATCH 37/41] fat: " Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29 ` [PATCH 38/41] swap: " Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29 ` Tejun Heo
2010-09-03 10:29 ` [PATCH 39/41] block: remove the WRITE_BARRIER flag Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29 ` [PATCH 40/41] block: remove the BLKDEV_IFL_BARRIER flag Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29 ` [PATCH 41/41] block: remove the BH_Eopnotsupp flag Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 10:29   ` Tejun Heo
2010-09-03 18:53 ` [PATCHSET #upstream] block, fs: replace HARDBARRIER with FLUSH/FUA, take#2 Jens Axboe
2010-09-03 18:53   ` Jens Axboe
2010-09-08 16:12 ` Tejun Heo
2010-09-08 16:12   ` Tejun Heo
2010-09-10 10:19   ` Jens Axboe
2010-09-10 10:19     ` Jens Axboe
2010-09-08 16:12 ` Tejun Heo

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