From: Kent Overstreet <koverstreet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
To: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org,
dm-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
agk-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org,
Junichi Nomura <j-nomura-JhyGz2TFV9J8UrSeD/g0lQ@public.gmane.org>,
Mikulas Patocka
<mpatocka-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Subject: Re: [dm-devel] [PATCH 02/13] dm: kill dm_rq_bio_destructor
Date: Fri, 18 May 2012 11:50:27 -0700 [thread overview]
Message-ID: <20120518185027.GA9673@google.com> (raw)
In-Reply-To: <20120518164319.GJ29330-FDJ95KluN3Z0klwcnFlA1dvLeJWuRmrY@public.gmane.org>
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.
Seems like it might be better to use bio set's front_pad to put it in
the same allocation as the bio, but I don't really want to get into that
myself.
WARNING: multiple messages have this Message-ID (diff)
From: Kent Overstreet <koverstreet@google.com>
To: Tejun Heo <tj@kernel.org>,
axboe@kernel.dk, dm-devel@redhat.com,
linux-kernel@vger.kernel.org, linux-bcache@vger.kernel.org,
linux-fsdevel@vger.kernel.org, agk@redhat.com,
Junichi Nomura <j-nomura@ce.jp.nec.com>,
Mikulas Patocka <mpatocka@redhat.com>
Subject: Re: [dm-devel] [PATCH 02/13] dm: kill dm_rq_bio_destructor
Date: Fri, 18 May 2012 11:50:27 -0700 [thread overview]
Message-ID: <20120518185027.GA9673@google.com> (raw)
In-Reply-To: <20120518164319.GJ29330@agk-dp.fab.redhat.com>
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.
Seems like it might be better to use bio set's front_pad to put it in
the same allocation as the bio, but I don't really want to get into that
myself.
next prev parent reply other threads:[~2012-05-18 18:50 UTC|newest]
Thread overview: 78+ 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 ` koverstreet
2012-05-18 2:59 ` [PATCH 01/13] block: Generalized bio pool freeing koverstreet
[not found] ` <ea774fea2a27c9f1028a12ce31a7ee5e5517bef4.1337308722.git.koverstreet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2012-05-18 15:55 ` Tejun Heo
2012-05-18 15:55 ` Tejun Heo
[not found] ` <20120518155538.GA19388-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2012-05-18 16:14 ` [dm-devel] " Alasdair G Kergon
2012-05-18 16:14 ` 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
[not found] ` <20120518155729.GB19388-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2012-05-18 16:43 ` [dm-devel] " Alasdair G Kergon
2012-05-18 16:43 ` Alasdair G Kergon
[not found] ` <20120518164319.GJ29330-FDJ95KluN3Z0klwcnFlA1dvLeJWuRmrY@public.gmane.org>
2012-05-18 18:50 ` Kent Overstreet [this message]
2012-05-18 18:50 ` Kent Overstreet
[not found] ` <20120518185027.GA9673-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2012-05-22 4:29 ` Jun'ichi Nomura
2012-05-22 4:29 ` Jun'ichi Nomura
2012-05-18 2:59 ` [PATCH 03/13] block: Add bio_clone_bioset() koverstreet
2012-05-18 2:59 ` koverstreet
2012-05-18 16:05 ` Tejun Heo
2012-05-18 20:31 ` Kent Overstreet
[not found] ` <eb6a7d3fe7ae203202bc365d7274ee531631a9ca.1337308722.git.koverstreet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2012-05-18 16:11 ` [dm-devel] " Vivek Goyal
2012-05-18 16:11 ` 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 2:59 ` koverstreet
[not found] ` <1c7c2d4b89bc3d0e907608cec37bcf0ee50f4c0e.1337308722.git.koverstreet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2012-05-18 16:09 ` Tejun Heo
2012-05-18 16:09 ` Tejun Heo
[not found] ` <20120518160903.GD19388-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2012-05-18 20:39 ` Kent Overstreet
2012-05-18 20:39 ` Kent Overstreet
2012-05-18 16:45 ` Boaz Harrosh
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 2:59 ` 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 2:59 ` koverstreet
2012-05-18 16:16 ` Tejun Heo
[not found] ` <20120518161608.GF19388-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2012-05-18 21:48 ` Kent Overstreet
2012-05-18 21:48 ` Kent Overstreet
2012-05-18 2:59 ` [PATCH 07/13] pktcdvd: Switch to bio_kmalloc() koverstreet
2012-05-18 2:59 ` koverstreet
[not found] ` <04a4d6c2c8b6f0097e3594c6e0932093afffc1da.1337308722.git.koverstreet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2012-05-18 16:18 ` Tejun Heo
2012-05-18 16:18 ` Tejun Heo
2012-05-18 2:59 ` [PATCH 08/13] block: Kill bi_destructor koverstreet
2012-05-18 2:59 ` koverstreet
[not found] ` <de05855cf0fa4800cfab7e8340f106dccc7a75a1.1337308722.git.koverstreet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2012-05-18 16:21 ` Tejun Heo
2012-05-18 16:21 ` Tejun Heo
[not found] ` <20120518162142.GH19388-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2012-05-18 22:21 ` Kent Overstreet
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
[not found] ` <363875943e9d0e13bee6ed28239280543e6e5055.1337308722.git.koverstreet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2012-05-18 16:30 ` Tejun Heo
2012-05-18 16:30 ` Tejun Heo
2012-05-18 21:49 ` Kent Overstreet
2012-05-18 17:07 ` Boaz Harrosh
2012-05-18 17:07 ` Boaz Harrosh
2012-05-18 17:07 ` Boaz Harrosh
2012-05-18 2:59 ` [PATCH 10/13] block: Rework bio splitting koverstreet
[not found] ` <ac4c1cbd10934fdc3a4af74d4cb5ec370f9139d5.1337308722.git.koverstreet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2012-05-18 17:07 ` Tejun Heo
2012-05-18 17:07 ` Tejun Heo
2012-05-18 17:46 ` Boaz Harrosh
2012-05-18 17:46 ` Boaz Harrosh
[not found] ` <cover.1337308722.git.koverstreet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2012-05-18 2:59 ` [PATCH 11/13] Closures koverstreet-hpIqsD4AKlfQT0dZR+AlfA
2012-05-18 2:59 ` koverstreet
[not found] ` <a184989cfbf92297d4cca2f823e5ac24ec8fe1e3.1337308722.git.koverstreet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2012-05-18 17:08 ` Tejun Heo
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
[not found] ` <20120518180550.0a6cdc34-wvvUuzkyo1EYVZTmpyfIwg@public.gmane.org>
2012-05-18 8:14 ` Kent Overstreet
2012-05-18 8:14 ` Kent Overstreet
[not found] ` <20120518081444.GA27205-RcKxWJ4Cfj3IzGYXcIpNmNLIRw13R84JkQQo+JxHRPFibQn6LdNjmg@public.gmane.org>
2012-05-21 17:17 ` [dm-devel] " Vivek Goyal
2012-05-21 17:17 ` 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
[not found] ` <1114e7019b0055fc09a54b59b36398d5c54f5e32.1337308722.git.koverstreet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2012-05-18 22:48 ` Mikulas Patocka
2012-05-18 22:48 ` Mikulas Patocka
2012-05-18 3:00 ` [PATCH 13/13] Gut bio_add_page() koverstreet
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