From: NeilBrown <neilb@suse.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Ilya Dryomov <idryomov@gmail.com>, Sage Weil <sage@redhat.com>,
Alex Elder <elder@kernel.org>,
ceph-devel@vger.kernel.org
Subject: [PATCH 05/11] rbd: use bio_clone_fast() instead of bio_clone()
Date: Thu, 20 Apr 2017 15:38:49 +1000 [thread overview]
Message-ID: <149266672920.27388.16945242936892893803.stgit@noble> (raw)
In-Reply-To: <149266645258.27388.14083229348123176454.stgit@noble>
bio_clone() makes a copy of the bi_io_vec, but rbd never changes that,
so there is no need for a copy.
bio_clone_fast() can be used instead, which avoids making the copy.
This requires that we provide a bio_set. bio_clone() uses fs_bio_set,
but it isn't, in general, safe to use the same bio_set at different
levels of the stack, as that can lead to deadlocks. As filesystems
use fs_bio_set, block devices shouldn't.
As rbd never stacks, it is safe to have a single global bio_set for
all rbd devices to use. So allocate that when the module is
initialised, and use it with bio_clone_fast().
Signed-off-by: NeilBrown <neilb@suse.com>
---
drivers/block/rbd.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 089ac4179919..48eecffc612e 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -441,6 +441,8 @@ static DEFINE_SPINLOCK(rbd_client_list_lock);
static struct kmem_cache *rbd_img_request_cache;
static struct kmem_cache *rbd_obj_request_cache;
+static struct bio_set *rbd_bio_clone;
+
static int rbd_major;
static DEFINE_IDA(rbd_dev_id_ida);
@@ -1362,7 +1364,7 @@ static struct bio *bio_clone_range(struct bio *bio_src,
{
struct bio *bio;
- bio = bio_clone(bio_src, gfpmask);
+ bio = bio_clone_fast(bio_src, gfpmask, rbd_bio_clone);
if (!bio)
return NULL; /* ENOMEM */
@@ -6342,8 +6344,16 @@ static int rbd_slab_init(void)
if (!rbd_obj_request_cache)
goto out_err;
+ rbd_assert(!rbd_bio_clone);
+ rbd_bio_clone = bioset_create(BIO_POOL_SIZE, 0);
+ if (!rbd_bio_clone)
+ goto out_err_clone;
+
return 0;
+out_err_clone:
+ kmem_cache_destroy(rbd_obj_request_cache);
+ rbd_obj_request_cache = NULL;
out_err:
kmem_cache_destroy(rbd_img_request_cache);
rbd_img_request_cache = NULL;
@@ -6359,6 +6369,10 @@ static void rbd_slab_exit(void)
rbd_assert(rbd_img_request_cache);
kmem_cache_destroy(rbd_img_request_cache);
rbd_img_request_cache = NULL;
+
+ rbd_assert(rbd_bio_clone);
+ bioset_free(rbd_bio_clone);
+ rbd_bio_clone = NULL;
}
static int __init rbd_init(void)
next prev parent reply other threads:[~2017-04-20 5:45 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-20 5:38 [PATCH 00/11] block: assorted cleanup for bio splitting and cloning NeilBrown
2017-04-20 5:38 ` [PATCH 01/11] blk: remove bio_set arg from blk_queue_split() NeilBrown
2017-04-21 11:21 ` Christoph Hellwig
2017-04-21 15:14 ` Ming Lei
2017-04-22 9:16 ` Javier González
2017-04-24 2:32 ` NeilBrown
2017-04-20 5:38 ` [PATCH 02/11] blk: make the bioset rescue_workqueue optional NeilBrown
2017-04-21 11:24 ` Christoph Hellwig
2017-04-24 1:51 ` NeilBrown
2017-04-24 15:10 ` Christoph Hellwig
2017-05-01 5:00 ` NeilBrown
2017-05-01 14:02 ` Jens Axboe
2017-05-02 3:33 ` NeilBrown
2017-04-20 5:38 ` [PATCH 07/11] pktcdvd: use bio_clone_fast() instead of bio_clone() NeilBrown
2017-04-21 11:29 ` Christoph Hellwig
2017-04-20 5:38 ` NeilBrown [this message]
2017-04-21 11:31 ` [PATCH 05/11] rbd: " Christoph Hellwig
2017-04-20 5:38 ` [PATCH 03/11] blk: use non-rescuing bioset for q->bio_split NeilBrown
2017-04-21 11:25 ` Christoph Hellwig
2017-04-20 5:38 ` [PATCH 04/11] block: Improvements to bounce-buffer handling NeilBrown
2017-04-21 11:28 ` Christoph Hellwig
2017-04-21 15:39 ` Ming Lei
2017-04-20 5:38 ` [PATCH 06/11] drbd: use bio_clone_fast() instead of bio_clone() NeilBrown
2017-04-21 11:30 ` Christoph Hellwig
2017-04-20 5:38 ` [PATCH 09/11] bcache: use kmalloc to allocate bio in bch_data_verify() NeilBrown
2017-04-21 11:31 ` Christoph Hellwig
2017-04-21 11:32 ` Kent Overstreet
2017-04-21 15:41 ` Ming Lei
2017-04-20 5:38 ` [PATCH 08/11] xen-blkfront: remove bio splitting NeilBrown
2017-04-20 10:00 ` Roger Pau Monné
2017-04-21 11:36 ` Christoph Hellwig
2017-04-21 11:46 ` Roger Pau Monne
2017-04-20 5:38 ` [PATCH 11/11] block: don't check for BIO_MAX_PAGES in blk_bio_segment_split() NeilBrown
2017-04-21 11:34 ` Christoph Hellwig
2017-04-21 15:48 ` Ming Lei
2017-04-24 3:16 ` NeilBrown
2017-04-24 3:14 ` NeilBrown
2017-04-20 5:38 ` [PATCH 10/11] block: remove bio_clone() and all references NeilBrown
2017-04-21 11:32 ` Christoph Hellwig
2017-04-21 15:43 ` Ming Lei
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