loop: cleanup lo_rw_aio

Port over the changes from the zloop driver to remove the need for
the local bio, bvec and offset variables and clean up the code by
that.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <tom.leiming@gmail.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Link: https://patch.msgid.link/20260527151043.2349900-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 0000913f7efcc1a9c77d2d1dd85851bfe502c617..310de0463beb149039119d1b931ae424c7f7b3f2 100644 (file)
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -342,23 +342,19 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
 {
        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;
        unsigned int nr_bvec;
        int ret;
 
        nr_bvec = blk_rq_nr_bvec(rq);
 
        if (rq->bio != rq->biotail) {
+               struct bio_vec tmp, *bvec;
 
-               bvec = kmalloc_objs(struct bio_vec, nr_bvec, GFP_NOIO);
-               if (!bvec)
+               cmd->bvec = kmalloc_objs(*cmd->bvec, nr_bvec, GFP_NOIO);
+               if (!cmd->bvec)
                        return -EIO;
-               cmd->bvec = bvec;
 
                /*
                 * The bios of the request may be started from the middle of
@@ -366,26 +362,26 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
                 * copy bio->bi_iov_vec to new bvec. The rq_for_each_bvec
                 * API will take care of all details for us.
                 */
+               bvec = cmd->bvec;
                rq_for_each_bvec(tmp, rq, rq_iter) {
                        *bvec = tmp;
                        bvec++;
                }
-               bvec = cmd->bvec;
-               offset = 0;
+               iov_iter_bvec(&iter, rw, cmd->bvec, nr_bvec, blk_rq_bytes(rq));
+               iter.iov_offset = 0;
        } else {
                /*
                 * Same here, this bio may be started from the middle of the
                 * 'bvec' because of bio splitting, so offset from the bvec
                 * must be passed to iov iterator
                 */
-               offset = bio->bi_iter.bi_bvec_done;
-               bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
+               iov_iter_bvec(&iter, rw,
+                       __bvec_iter_bvec(rq->bio->bi_io_vec, rq->bio->bi_iter),
+                       nr_bvec, blk_rq_bytes(rq));
+               iter.iov_offset = rq->bio->bi_iter.bi_bvec_done;
        }
        atomic_set(&cmd->ref, 2);
 
-       iov_iter_bvec(&iter, rw, bvec, nr_bvec, blk_rq_bytes(rq));
-       iter.iov_offset = offset;
-
        cmd->iocb.ki_pos = pos;
        cmd->iocb.ki_filp = file;
        cmd->iocb.ki_ioprio = req_get_ioprio(rq);