[V12,14/20] bcache: avoid to use bio_for_each_segment_all() in bch_bio_alloc_pages()
diff mbox series

Message ID 20181126021720.19471-15-ming.lei@redhat.com
State New
Headers show
Series
  • block: support multi-page bvec
Related show

Commit Message

Ming Lei Nov. 26, 2018, 2:17 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>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 drivers/md/bcache/util.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

Comments

Omar Sandoval Nov. 26, 2018, 10:40 p.m. UTC | #1
On Mon, Nov 26, 2018 at 10:17:14AM +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.
> 
> Acked-by: Coly Li <colyli@suse.de>
> Reviewed-by: Christoph Hellwig <hch@lst.de>

Reviewed-by: Omar Sandoval <osandov@fb.com>

> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
>  drivers/md/bcache/util.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> 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)
> -- 
> 2.9.5
>

Patch
diff mbox series

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)