| Message ID | 20181126021720.19471-14-ming.lei@redhat.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
| Series | block: support multi-page bvec | expand |
On Mon, Nov 26, 2018 at 10:17:13AM +0800, Ming Lei wrote: > iov_iter is implemented on bvec itererator helpers, so it is safe to pass > multi-page bvec to it, and this way is much more efficient than passing one > page in each bvec. > > Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Omar Sandoval <osandov@fb.com> > Signed-off-by: Ming Lei <ming.lei@redhat.com> > --- > drivers/block/loop.c | 20 ++++++++++---------- > 1 file changed, 10 insertions(+), 10 deletions(-) > > diff --git a/drivers/block/loop.c b/drivers/block/loop.c > index 176ab1f28eca..e3683211f12d 100644 > --- a/drivers/block/loop.c > +++ b/drivers/block/loop.c > @@ -510,21 +510,22 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, > loff_t pos, bool rw) > { > struct iov_iter iter; > + struct req_iterator rq_iter; > struct bio_vec *bvec; > struct request *rq = blk_mq_rq_from_pdu(cmd); > struct bio *bio = rq->bio; > struct file *file = lo->lo_backing_file; > + struct bio_vec tmp; > unsigned int offset; > - int segments = 0; > + int nr_bvec = 0; > int ret; > > + rq_for_each_bvec(tmp, rq, rq_iter) > + nr_bvec++; > + > if (rq->bio != rq->biotail) { > - struct req_iterator iter; > - struct bio_vec tmp; > > - __rq_for_each_bio(bio, rq) > - segments += bio_segments(bio); > - bvec = kmalloc_array(segments, sizeof(struct bio_vec), > + bvec = kmalloc_array(nr_bvec, sizeof(struct bio_vec), > GFP_NOIO); > if (!bvec) > return -EIO; > @@ -533,10 +534,10 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, > /* > * The bios of the request may be started from the middle of > * the 'bvec' because of bio splitting, so we can't directly > - * copy bio->bi_iov_vec to new bvec. The rq_for_each_segment > + * copy bio->bi_iov_vec to new bvec. The rq_for_each_bvec > * API will take care of all details for us. > */ > - rq_for_each_segment(tmp, rq, iter) { > + rq_for_each_bvec(tmp, rq, rq_iter) { > *bvec = tmp; > bvec++; > } > @@ -550,11 +551,10 @@ 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); > - segments = bio_segments(bio); > } > atomic_set(&cmd->ref, 2); > > - iov_iter_bvec(&iter, rw, bvec, segments, blk_rq_bytes(rq)); > + iov_iter_bvec(&iter, rw, bvec, nr_bvec, blk_rq_bytes(rq)); > iter.iov_offset = offset; > > cmd->iocb.ki_pos = pos; > -- > 2.9.5 >
diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 176ab1f28eca..e3683211f12d 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -510,21 +510,22 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, loff_t pos, bool rw) { struct iov_iter iter; + struct req_iterator rq_iter; struct bio_vec *bvec; struct request *rq = blk_mq_rq_from_pdu(cmd); struct bio *bio = rq->bio; struct file *file = lo->lo_backing_file; + struct bio_vec tmp; unsigned int offset; - int segments = 0; + int nr_bvec = 0; int ret; + rq_for_each_bvec(tmp, rq, rq_iter) + nr_bvec++; + if (rq->bio != rq->biotail) { - struct req_iterator iter; - struct bio_vec tmp; - __rq_for_each_bio(bio, rq) - segments += bio_segments(bio); - bvec = kmalloc_array(segments, sizeof(struct bio_vec), + bvec = kmalloc_array(nr_bvec, sizeof(struct bio_vec), GFP_NOIO); if (!bvec) return -EIO; @@ -533,10 +534,10 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, /* * The bios of the request may be started from the middle of * the 'bvec' because of bio splitting, so we can't directly - * copy bio->bi_iov_vec to new bvec. The rq_for_each_segment + * copy bio->bi_iov_vec to new bvec. The rq_for_each_bvec * API will take care of all details for us. */ - rq_for_each_segment(tmp, rq, iter) { + rq_for_each_bvec(tmp, rq, rq_iter) { *bvec = tmp; bvec++; } @@ -550,11 +551,10 @@ 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); - segments = bio_segments(bio); } atomic_set(&cmd->ref, 2); - iov_iter_bvec(&iter, rw, bvec, segments, blk_rq_bytes(rq)); + iov_iter_bvec(&iter, rw, bvec, nr_bvec, blk_rq_bytes(rq)); iter.iov_offset = offset; cmd->iocb.ki_pos = pos;