From mboxrd@z Thu Jan 1 00:00:00 1970 From: Junichi Nomura Subject: [PATCH 1/4] dm: remove nr_iovecs parameter from alloc_tio() Date: Fri, 3 Oct 2014 11:55:16 +0000 Message-ID: <542E8EA4.2010704@ce.jp.nec.com> References: <542E8CF9.6000609@ce.jp.nec.com> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <542E8CF9.6000609@ce.jp.nec.com> Content-Language: ja-JP Content-ID: <7D67CBFB1F67B14597FE2A62CC226E8D@gisp.nec.co.jp> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: device-mapper development , Mike Snitzer Cc: Jens Axboe , Kent Overstreet List-Id: dm-devel.ids 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 --- drivers/md/dm.c | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 32b958d..4210b3c 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1249,13 +1249,13 @@ static void clone_bio(struct dm_target_io *tio, struct bio *bio, } static struct dm_target_io *alloc_tio(struct clone_info *ci, - struct dm_target *ti, int nr_iovecs, + struct dm_target *ti, unsigned target_bio_nr) { struct dm_target_io *tio; struct bio *clone; - clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, ci->md->bs); + clone = bio_alloc_bioset(GFP_NOIO, 0, ci->md->bs); tio = container_of(clone, struct dm_target_io, clone); tio->io = ci->io; @@ -1269,16 +1269,11 @@ static void __clone_and_map_simple_bio(struct clone_info *ci, struct dm_target *ti, unsigned target_bio_nr, unsigned *len) { - struct dm_target_io *tio = alloc_tio(ci, ti, ci->bio->bi_max_vecs, target_bio_nr); + struct dm_target_io *tio = alloc_tio(ci, ti, target_bio_nr); struct bio *clone = &tio->clone; tio->len_ptr = len; - /* - * Discard requests require the bio's inline iovecs be initialized. - * ci->bio->bi_max_vecs is BIO_INLINE_VECS anyway, for both flush - * and discard, so no need for concern about wasted bvec allocations. - */ __bio_clone_fast(clone, ci->bio); if (len) bio_setup_sector(clone, ci->sector, *len); @@ -1322,7 +1317,7 @@ static void __clone_and_map_data_bio(struct clone_info *ci, struct dm_target *ti num_target_bios = ti->num_write_bios(ti, bio); for (target_bio_nr = 0; target_bio_nr < num_target_bios; target_bio_nr++) { - tio = alloc_tio(ci, ti, 0, target_bio_nr); + tio = alloc_tio(ci, ti, target_bio_nr); tio->len_ptr = len; clone_bio(tio, bio, sector, *len); __map_bio(tio); -- 1.9.3