diff mbox series

[V11,11/19] bcache: avoid to use bio_for_each_segment_all() in bch_bio_alloc_pages()

Message ID 20181121032327.8434-12-ming.lei@redhat.com (mailing list archive)
State Not Applicable, archived
Headers show
Series block: support multi-page bvec | expand

Commit Message

Ming Lei Nov. 21, 2018, 3:23 a.m. UTC 
bch_bio_alloc_pages() is always called on one new bio, so it is safe
to access the bvec table directly. Given it is the only kind of this
case, open code the bvec table access since bio_for_each_segment_all()
will be changed to support for iterating over multipage bvec.

Acked-by: Coly Li <colyli@suse.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 drivers/md/bcache/util.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

Comments

Christoph Hellwig Nov. 21, 2018, 2:01 p.m. UTC | #1 
On Wed, Nov 21, 2018 at 11:23:19AM +0800, Ming Lei wrote:
> bch_bio_alloc_pages() is always called on one new bio, so it is safe
> to access the bvec table directly. Given it is the only kind of this
> case, open code the bvec table access since bio_for_each_segment_all()
> will be changed to support for iterating over multipage bvec.

Looks good,

Reviewed-by: Christoph Hellwig <hch@lst.de>
diff mbox series

Patch

diff --git a/drivers/md/bcache/util.c b/drivers/md/bcache/util.c
index 20eddeac1531..62fb917f7a4f 100644
--- a/drivers/md/bcache/util.c
+++ b/drivers/md/bcache/util.c
@@ -270,7 +270,11 @@  int bch_bio_alloc_pages(struct bio *bio, gfp_t gfp_mask)
 	int i;
 	struct bio_vec *bv;
 
-	bio_for_each_segment_all(bv, bio, i) {
+	/*
+	 * This is called on freshly new bio, so it is safe to access the
+	 * bvec table directly.
+	 */
+	for (i = 0, bv = bio->bi_io_vec; i < bio->bi_vcnt; bv++, i++) {
 		bv->bv_page = alloc_page(gfp_mask);
 		if (!bv->bv_page) {
 			while (--bv >= bio->bi_io_vec)