lkml.org 
[lkml]   [2018]   [Nov]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH V11 10/19] block: loop: pass multi-page bvec to iov_iter
    Date
    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.

    Signed-off-by: Ming Lei <ming.lei@redhat.com>
    ---
    drivers/block/loop.c | 20 ++++++++++----------
    include/linux/blkdev.h | 4 ++++
    2 files changed, 14 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;
    diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
    index 1ad6eafc43f2..a281b6737b61 100644
    --- a/include/linux/blkdev.h
    +++ b/include/linux/blkdev.h
    @@ -805,6 +805,10 @@ struct req_iterator {
    __rq_for_each_bio(_iter.bio, _rq) \
    bio_for_each_segment(bvl, _iter.bio, _iter.iter)

    +#define rq_for_each_bvec(bvl, _rq, _iter) \
    + __rq_for_each_bio(_iter.bio, _rq) \
    + bio_for_each_bvec(bvl, _iter.bio, _iter.iter)
    +
    #define rq_iter_last(bvec, _iter) \
    (_iter.bio->bi_next == NULL && \
    bio_iter_last(bvec, _iter.iter))
    --
    2.9.5
    \
     
     \ /
      Last update: 2018-11-21 04:27    [W:4.110 / U:0.500 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site