From: Kent Overstreet <koverstreet@google.com>
To: Muthu Kumar <muthu.lkml@gmail.com>
Cc: Tejun Heo <tj@kernel.org>, Mikulas Patocka <mpatocka@redhat.com>,
device-mapper development <dm-devel@redhat.com>,
linux-bcache@vger.kernel.org, linux-kernel@vger.kernel.org,
axboe@kernel.dk, vgoyal@redhat.com, yehuda@hq.newdream.net,
sage@newdream.net, agk@redhat.com, drbd-dev@lists.linbit.com
Subject: Re: [dm-devel] [PATCH v5 12/12] block: Only clone bio vecs that are in use
Date: Wed, 8 Aug 2012 20:25:03 -0700 [thread overview]
Message-ID: <CAH+dOxKr=BcWO5qmYZkrc2px+ckx=_+viWQ9M2hE7RMA3DaXNg@mail.gmail.com> (raw)
In-Reply-To: <20120809031936.GM7262@moria.home.lan>
On Wed, Aug 8, 2012 at 8:19 PM, Kent Overstreet <koverstreet@google.com> wrote:
> In particular, if this change breaks anything then the new bio_split()
> _will_ break things.
>
> We need to be clear about our interfaces; in this case bi_idx and
> bi_vcnt, in particular. Either this is a safe change, or it's not. If
> no one knows... that's a bigger problem, and not just for this patch...
>
> Fortunately this code actually has been tested quite a bit (and the bio
> splitting code for even longer), and (somewhat to my surprise) I haven't
> run into any bugs caused by it.
Oh, it's worse than that - remember how bio_kmalloc() works for up to
1024 pages, but bio_alloc_bioset() only up to 256?
We can already have situations where bios are allocated that are
impossible to clone (or if we don't, it's only because of
queue_limits. That's not sketchy at all.)
next prev parent reply other threads:[~2012-08-09 3:25 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-06 22:08 [PATCH v5 00/12] Block cleanups Kent Overstreet
2012-08-06 22:08 ` [PATCH v5 01/12] block: Generalized bio pool freeing Kent Overstreet
2012-08-08 22:25 ` Tejun Heo
2012-08-09 0:26 ` Kent Overstreet
2012-08-06 22:08 ` [PATCH v5 02/12] dm: Use bioset's front_pad for dm_rq_clone_bio_info Kent Overstreet
2012-08-08 22:06 ` Tejun Heo
2012-08-08 23:57 ` Kent Overstreet
2012-08-11 5:24 ` Joseph Glanville
2012-08-13 21:44 ` Kent Overstreet
2012-08-14 5:33 ` Jun'ichi Nomura
2012-08-15 20:46 ` Kent Overstreet
2012-08-06 22:08 ` [PATCH v5 03/12] block: Add bio_reset() Kent Overstreet
2012-08-08 22:11 ` Tejun Heo
2012-08-09 0:07 ` Kent Overstreet
2012-08-09 6:00 ` Tejun Heo
2012-08-09 6:06 ` Kent Overstreet
2012-08-09 6:30 ` Tejun Heo
2012-08-06 22:08 ` [PATCH v5 04/12] pktcdvd: Switch to bio_kmalloc() Kent Overstreet
2012-08-08 22:13 ` Tejun Heo
2012-08-09 0:08 ` Kent Overstreet
2012-08-06 22:08 ` [PATCH v5 05/12] block: Kill bi_destructor Kent Overstreet
2012-08-07 3:19 ` Mike Snitzer
2012-08-09 0:14 ` Kent Overstreet
2012-08-08 22:22 ` Tejun Heo
2012-08-09 0:21 ` Kent Overstreet
2012-08-09 6:05 ` Tejun Heo
2012-08-09 6:12 ` Kent Overstreet
2012-08-09 6:34 ` Tejun Heo
2012-08-15 22:19 ` Kent Overstreet
2012-08-06 22:08 ` [PATCH v5 06/12] block: Add an explicit bio flag for bios that own their bvec Kent Overstreet
2012-08-08 22:28 ` Tejun Heo
2012-08-06 22:08 ` [PATCH v5 07/12] block: Rename bio_split() -> bio_pair_split() Kent Overstreet
2012-08-06 22:08 ` [PATCH v5 08/12] block: Introduce new bio_split() Kent Overstreet
2012-08-08 22:58 ` Tejun Heo
2012-08-09 1:19 ` Kent Overstreet
2012-08-09 6:44 ` Tejun Heo
2012-08-13 21:55 ` Kent Overstreet
2012-08-13 22:05 ` Tejun Heo
2012-08-08 23:05 ` Tejun Heo
2012-08-09 1:39 ` Kent Overstreet
2012-08-09 7:22 ` Tejun Heo
2012-08-09 7:33 ` Kent Overstreet
2012-08-09 17:32 ` Tejun Heo
2012-08-13 22:09 ` Kent Overstreet
2012-08-06 22:08 ` [PATCH v5 09/12] block: Rework bio_pair_split() Kent Overstreet
2012-08-08 23:09 ` Tejun Heo
2012-08-06 22:08 ` [PATCH v5 10/12] block: Add bio_clone_kmalloc() Kent Overstreet
2012-08-08 23:15 ` Tejun Heo
2012-08-09 1:57 ` Kent Overstreet
2012-08-09 6:55 ` Tejun Heo
2012-08-09 7:02 ` Kent Overstreet
2012-08-09 2:38 ` [PATCH] Consolidate bio_clone_bioset(), bio_kmalloc() Kent Overstreet
2012-08-09 6:56 ` Tejun Heo
2012-08-06 22:08 ` [PATCH v5 11/12] block: Add bio_clone_bioset() Kent Overstreet
2012-08-08 23:21 ` Tejun Heo
2012-08-09 2:56 ` Kent Overstreet
2012-08-09 6:52 ` Tejun Heo
2012-08-09 6:59 ` Kent Overstreet
2012-08-06 22:08 ` [PATCH v5 12/12] block: Only clone bio vecs that are in use Kent Overstreet
2012-08-06 23:16 ` [dm-devel] " Mikulas Patocka
2012-08-08 23:28 ` Tejun Heo
2012-08-08 23:47 ` Muthu Kumar
2012-08-09 3:19 ` Kent Overstreet
2012-08-09 3:25 ` Kent Overstreet [this message]
2012-08-10 1:50 ` Muthu Kumar
2012-08-09 7:01 ` Tejun Heo
2012-08-10 2:29 ` Muthu Kumar
2012-08-08 23:30 ` Tejun Heo
2012-08-09 3:06 ` Kent Overstreet
2012-08-09 17:37 ` Tejun Heo
2012-08-13 21:46 ` Kent Overstreet
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