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From: "Jun'ichi Nomura" <j-nomura@ce.jp.nec.com>
To: device-mapper development <dm-devel@redhat.com>,
	Kent Overstreet <koverstreet@google.com>
Cc: Tejun Heo <tj@kernel.org>,
	axboe@kernel.dk, linux-kernel@vger.kernel.org,
	linux-bcache@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	agk@redhat.com, Mikulas Patocka <mpatocka@redhat.com>
Subject: Re: [dm-devel] [PATCH 02/13] dm: kill dm_rq_bio_destructor
Date: Tue, 22 May 2012 13:29:01 +0900	[thread overview]
Message-ID: <4FBB160D.9040600@ce.jp.nec.com> (raw)
In-Reply-To: <20120518185027.GA9673@google.com>

Hi,

On 05/19/12 03:50, Kent Overstreet wrote:
> On Fri, May 18, 2012 at 05:43:19PM +0100, Alasdair G Kergon wrote:
>> On Fri, May 18, 2012 at 08:57:29AM -0700, Tejun Heo wrote:
>>> Please explain why this is done and how it's safe.  Alasdair / dm
>>> folks, can you please ack this?
>>  
>> I think it's relying on there being never more than one reference on those 
>> bios so that that endio fn, called exactly once, always frees it and there
>> are no dm_puts elsewhere.
> 
> Is that a safe assumption? From my perusal of the code it certainly
> looks like it should be, but I don't know dm all that well.

Doing free_bio_info() in end_clone_bio() is safe.

But there is other problem.
This bio may be put by blk_rq_unprep_clone() and leak memory
without the destructor.

So could it be possible to keep bi_destructor available for this case?

Thanks,
-- 
Jun'ichi Nomura, NEC Corporation

  reply	other threads:[~2012-05-22  4:32 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-05-18  2:59 [PATCH 00/13] Block cleanups (for bcache) koverstreet
2012-05-18  2:59 ` [PATCH 01/13] block: Generalized bio pool freeing koverstreet
2012-05-18 15:55   ` Tejun Heo
2012-05-18 16:14     ` [dm-devel] " Alasdair G Kergon
2012-05-18  2:59 ` [PATCH 02/13] dm: kill dm_rq_bio_destructor koverstreet
2012-05-18 15:57   ` Tejun Heo
2012-05-18 16:43     ` [dm-devel] " Alasdair G Kergon
2012-05-18 18:50       ` Kent Overstreet
2012-05-22  4:29         ` Jun'ichi Nomura [this message]
2012-05-18  2:59 ` [PATCH 03/13] block: Add bio_clone_bioset() koverstreet
2012-05-18 16:05   ` Tejun Heo
2012-05-18 20:31     ` Kent Overstreet
2012-05-18 16:11   ` [dm-devel] " Vivek Goyal
2012-05-18 18:55     ` Kent Overstreet
2012-05-18  2:59 ` [PATCH 04/13] block: Add bio_clone_kmalloc() koverstreet
2012-05-18 16:09   ` Tejun Heo
2012-05-18 20:39     ` Kent Overstreet
2012-05-18 16:45   ` Boaz Harrosh
2012-05-18  2:59 ` [PATCH 05/13] block: Only clone bio vecs that are in use koverstreet
2012-05-18 16:13   ` Tejun Heo
2012-05-18 21:14     ` Kent Overstreet
2012-05-18  2:59 ` [PATCH 06/13] block: Add bio_reset() koverstreet
2012-05-18 16:16   ` Tejun Heo
2012-05-18 21:48     ` Kent Overstreet
2012-05-18  2:59 ` [PATCH 07/13] pktcdvd: Switch to bio_kmalloc() koverstreet
2012-05-18 16:18   ` Tejun Heo
2012-05-18  2:59 ` [PATCH 08/13] block: Kill bi_destructor koverstreet
2012-05-18 16:21   ` Tejun Heo
2012-05-18 22:21     ` Kent Overstreet
2012-05-18  2:59 ` [PATCH 09/13] block: Add an explicit bio flag for bios that own their bvec koverstreet
2012-05-18 16:30   ` Tejun Heo
2012-05-18 21:49     ` Kent Overstreet
2012-05-18 17:07   ` Boaz Harrosh
2012-05-18  2:59 ` [PATCH 10/13] block: Rework bio splitting koverstreet
2012-05-18 17:07   ` Tejun Heo
2012-05-18 17:46   ` Boaz Harrosh
2012-05-18  2:59 ` [PATCH 11/13] Closures koverstreet
2012-05-18 17:08   ` Tejun Heo
2012-05-18  2:59 ` [PATCH 12/13] Make generic_make_request handle arbitrarily large bios koverstreet
2012-05-18  8:05   ` NeilBrown
2012-05-18  8:14     ` Kent Overstreet
2012-05-21 17:17       ` [dm-devel] " Vivek Goyal
2012-05-21 17:55         ` Kent Overstreet
2012-05-21 18:32           ` Vivek Goyal
2012-05-18 17:52   ` Tejun Heo
2012-05-19  0:59     ` [dm-devel] " Alasdair G Kergon
2012-05-18 22:48   ` Mikulas Patocka
2012-05-18  3:00 ` [PATCH 13/13] Gut bio_add_page() koverstreet

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