From: Mike Snitzer <snitzer@redhat.com>
To: Junichi Nomura <j-nomura@ce.jp.nec.com>
Cc: Jens Axboe <axboe@kernel.dk>,
device-mapper development <dm-devel@redhat.com>,
Kent Overstreet <kmo@daterainc.com>
Subject: Re: [PATCH 1/4] dm: remove nr_iovecs parameter from alloc_tio()
Date: Fri, 3 Oct 2014 16:01:30 -0400 [thread overview]
Message-ID: <20141003200129.GA13982@redhat.com> (raw)
In-Reply-To: <542E8EA4.2010704@ce.jp.nec.com>
On Fri, Oct 03 2014 at 7:55am -0400,
Junichi Nomura <j-nomura@ce.jp.nec.com> wrote:
> alloc_tio() allocates a bio for clone. It takes the number of
> bvecs to allocate for the clone-bio.
> However, with the introduction of bio_clone_fast() in v3.14,
> we no longer need to allocate bvecs and nr_iovecs is always 0.
>
> __clone_and_map_simple_bio() looks like passing non-zero
> nr_iovecs, but its value is always within the range of
> inline bvecs and no allocation actually happens.
> If allocation happened, BUG_ON() in __bio_clone_fast() would
> trigger.
>
> This patch removes the nr_iovecs parameter from alloc_tio()
> to prevent possible future mis-use of the interface.
>
> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
I picked this patch up and staged in linux-dm.git's for-next, see:
https://git.kernel.org/cgit/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=for-next&id=8d59090cdc0ea91ffc390f78d0406baf8f66ae38
next prev parent reply other threads:[~2014-10-03 20:01 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-03 11:48 [PATCH 0/4] dm: reduce memory overhead of DM devices Junichi Nomura
2014-10-03 11:55 ` [PATCH 1/4] dm: remove nr_iovecs parameter from alloc_tio() Junichi Nomura
2014-10-03 20:01 ` Mike Snitzer [this message]
2014-10-03 11:55 ` [PATCH 2/4] block: use bio_clone_fast() in blk_rq_prep_clone() Junichi Nomura
2014-10-03 11:55 ` [PATCH 3/4] block: add bioset_nobvec_create() Junichi Nomura
2014-10-03 13:16 ` Mike Snitzer
2014-10-03 11:55 ` [PATCH 4/4] dm: use bioset_nobvec_create() Junichi Nomura
2014-10-03 13:23 ` [PATCH 0/4] dm: reduce memory overhead of DM devices Mike Snitzer
2014-10-03 20:48 ` Mike Snitzer
2014-10-03 20:57 ` Jens Axboe
2014-10-03 21:04 ` Mike Snitzer
2014-10-03 21:27 ` [PATCH v2 1/4] dm: remove nr_iovecs parameter from alloc_tio() Mike Snitzer
2014-10-03 21:27 ` [PATCH v2 2/4] block: use bio_clone_fast() in blk_rq_prep_clone() Mike Snitzer
2014-10-03 21:27 ` [PATCH v2 3/4] block: add bioset_create_nobvec() Mike Snitzer
2014-10-03 21:27 ` [PATCH v2 4/4] dm: use bioset_create_nobvec() Mike Snitzer
2014-10-05 23:06 ` Junichi Nomura
2014-10-06 0:24 ` Mike Snitzer
2014-10-04 17:01 ` [PATCH 0/4] dm: reduce memory overhead of DM devices Christoph Hellwig
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