Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756989Ab2HFXQx (ORCPT ); Mon, 6 Aug 2012 19:16:53 -0400 Received: from mx1.redhat.com ([209.132.183.28]:3834 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751697Ab2HFXQv (ORCPT ); Mon, 6 Aug 2012 19:16:51 -0400 Date: Mon, 6 Aug 2012 19:16:33 -0400 (EDT) From: Mikulas Patocka X-X-Sender: mpatocka@file.rdu.redhat.com To: device-mapper development cc: linux-bcache@vger.kernel.org, linux-kernel@vger.kernel.org, axboe@kernel.dk, Kent Overstreet , vgoyal@redhat.com, yehuda@hq.newdream.net, tj@kernel.org, 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 In-Reply-To: <1344290921-25154-13-git-send-email-koverstreet@google.com> Message-ID: References: <1344290921-25154-1-git-send-email-koverstreet@google.com> <1344290921-25154-13-git-send-email-koverstreet@google.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3871 Lines: 118 Hi Kent When you change the semantics of an exported function, rename that function. There may be external modules that use __bio_clone and this change could silently introduce bugs in them. Otherwise, the patchset looks fine. Mikulas On Mon, 6 Aug 2012, Kent Overstreet wrote: > bcache creates large bios internally, and then splits them according to > the device requirements before it sends them down. If a lower level > device tries to clone the bio, and the original bio had more than > BIO_MAX_PAGES, the clone will fail unecessarily. > > We can fix this by only cloning the bio vecs that are actually in use. > > Signed-off-by: Kent Overstreet > --- > drivers/block/rbd.c | 2 +- > drivers/md/dm.c | 5 ++--- > fs/bio.c | 13 +++++++------ > 3 files changed, 10 insertions(+), 10 deletions(-) > > diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c > index 692cf05..21edfe5 100644 > --- a/drivers/block/rbd.c > +++ b/drivers/block/rbd.c > @@ -714,7 +714,7 @@ static struct bio *bio_chain_clone(struct bio **old, struct bio **next, > } > > while (old_chain && (total < len)) { > - tmp = bio_kmalloc(gfpmask, old_chain->bi_max_vecs); > + tmp = bio_kmalloc(gfpmask, bio_segments(old_chain)); > if (!tmp) > goto err_out; > > diff --git a/drivers/md/dm.c b/drivers/md/dm.c > index 3f3c26e..193fb19 100644 > --- a/drivers/md/dm.c > +++ b/drivers/md/dm.c > @@ -1057,11 +1057,10 @@ static struct bio *clone_bio(struct bio *bio, sector_t sector, > { > struct bio *clone; > > - clone = bio_alloc_bioset(GFP_NOIO, bio->bi_max_vecs, bs); > + clone = bio_alloc_bioset(GFP_NOIO, bv_count, bs); > __bio_clone(clone, bio); > clone->bi_sector = sector; > - clone->bi_idx = idx; > - clone->bi_vcnt = idx + bv_count; > + clone->bi_vcnt = bv_count; > clone->bi_size = to_bytes(len); > clone->bi_flags &= ~(1 << BIO_SEG_VALID); > > diff --git a/fs/bio.c b/fs/bio.c > index 38ad026..631c67e 100644 > --- a/fs/bio.c > +++ b/fs/bio.c > @@ -449,8 +449,9 @@ EXPORT_SYMBOL(bio_phys_segments); > */ > void __bio_clone(struct bio *bio, struct bio *bio_src) > { > - memcpy(bio->bi_io_vec, bio_src->bi_io_vec, > - bio_src->bi_max_vecs * sizeof(struct bio_vec)); > + memcpy(bio->bi_io_vec, > + bio_iovec(bio_src), > + bio_segments(bio_src) * sizeof(struct bio_vec)); > > /* > * most users will be overriding ->bi_bdev with a new target, > @@ -459,10 +460,10 @@ void __bio_clone(struct bio *bio, struct bio *bio_src) > bio->bi_sector = bio_src->bi_sector; > bio->bi_bdev = bio_src->bi_bdev; > bio->bi_flags |= 1 << BIO_CLONED; > + bio->bi_flags &= ~(1 << BIO_SEG_VALID); > bio->bi_rw = bio_src->bi_rw; > - bio->bi_vcnt = bio_src->bi_vcnt; > + bio->bi_vcnt = bio_segments(bio_src); > bio->bi_size = bio_src->bi_size; > - bio->bi_idx = bio_src->bi_idx; > } > EXPORT_SYMBOL(__bio_clone); > > @@ -477,7 +478,7 @@ EXPORT_SYMBOL(__bio_clone); > struct bio *bio_clone_bioset(struct bio *bio, gfp_t gfp_mask, > struct bio_set *bs) > { > - struct bio *b = bio_alloc_bioset(gfp_mask, bio->bi_max_vecs, bs); > + struct bio *b = bio_alloc_bioset(gfp_mask, bio_segments(bio), bs); > > if (!b) > return NULL; > @@ -507,7 +508,7 @@ EXPORT_SYMBOL(bio_clone); > > struct bio *bio_clone_kmalloc(struct bio *bio, gfp_t gfp_mask) > { > - struct bio *b = bio_kmalloc(gfp_mask, bio->bi_max_vecs); > + struct bio *b = bio_kmalloc(gfp_mask, bio_segments(bio)); > > if (!b) > return NULL; > -- > 1.7.7.3 > > -- > dm-devel mailing list > dm-devel@redhat.com > https://www.redhat.com/mailman/listinfo/dm-devel > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/