Re: [PATCH V10 09/19] block: introduce bio_bvecs()
From: Christoph Hellwig <hch@lst.de>
Date: 2018-11-16 13:45:41
Also in:
dm-devel, linux-bcache, linux-btrfs, linux-ext4, linux-fsdevel, linux-mm, linux-raid, linux-xfs, lkml
Subsystem:
block layer, the rest · Maintainers:
Jens Axboe, Linus Torvalds
On Thu, Nov 15, 2018 at 04:52:56PM +0800, Ming Lei wrote:
There are still cases in which we need to use bio_bvecs() for get the number of multi-page segment, so introduce it.
The only user in your final tree seems to be the loop driver, and even that one only uses the helper for read/write bios. I think something like this would be much simpler in the end:
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index d509902a8046..712511815ac6 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c@@ -514,16 +514,18 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, struct request *rq = blk_mq_rq_from_pdu(cmd); struct bio *bio = rq->bio; struct file *file = lo->lo_backing_file; + struct bvec_iter bvec_iter; + struct bio_vec tmp; unsigned int offset; int nr_bvec = 0; int ret; + __rq_for_each_bio(bio, rq) + bio_for_each_bvec(tmp, bio, bvec_iter) + nr_bvec++; + if (rq->bio != rq->biotail) { - struct bvec_iter iter; - struct bio_vec tmp; - __rq_for_each_bio(bio, rq) - nr_bvec += bio_bvecs(bio); bvec = kmalloc_array(nr_bvec, sizeof(struct bio_vec), GFP_NOIO); if (!bvec)
@@ -537,7 +539,7 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, * API will take care of all details for us. */ __rq_for_each_bio(bio, rq) - bio_for_each_bvec(tmp, bio, iter) { + bio_for_each_bvec(tmp, bio, bvec_iter) { *bvec = tmp; bvec++; }
@@ -551,7 +553,6 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, */ offset = bio->bi_iter.bi_bvec_done; bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter); - nr_bvec = bio_bvecs(bio); } atomic_set(&cmd->ref, 2);
diff --git a/include/linux/bio.h b/include/linux/bio.h
index dcad0b69f57a..379440d1ced0 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h@@ -200,30 +200,6 @@ static inline unsigned bio_segments(struct bio *bio) } } -static inline unsigned bio_bvecs(struct bio *bio) -{ - unsigned bvecs = 0; - struct bio_vec bv; - struct bvec_iter iter; - - /* - * We special case discard/write same/write zeroes, because they - * interpret bi_size differently: - */ - switch (bio_op(bio)) { - case REQ_OP_DISCARD: - case REQ_OP_SECURE_ERASE: - case REQ_OP_WRITE_ZEROES: - return 0; - case REQ_OP_WRITE_SAME: - return 1; - default: - bio_for_each_bvec(bv, bio, iter) - bvecs++; - return bvecs; - } -} - /* * get a reference to a bio, so it won't disappear. the intended use is * something like: