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loop: add lo_submit_rw_aio() 

Refactor lo_rw_aio() by extracting the I/O submission logic into a new
helper function lo_submit_rw_aio(). This further improves code organization
by separating the I/O preparation, submission, and completion handling into
distinct phases.

Prepare for using NOWAIT to improve loop performance.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Ming Lei 2025-10-15 19:07:28 +08:00 committed by Jens Axboe
parent fd858d1ca9
commit c66e9708f9
1 changed files with 24 additions and 17 deletions
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41
drivers/block/loop.c
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@ -393,38 +393,32 @@ static int lo_rw_aio_prep(struct loop_device *lo, struct loop_cmd *cmd,
return 0;
}
static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
loff_t pos, int rw)
static int lo_submit_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
int nr_bvec, int rw)
{
struct iov_iter 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;
unsigned int offset;
int nr_bvec = lo_cmd_nr_bvec(cmd);
struct iov_iter iter;
int ret;
ret = lo_rw_aio_prep(lo, cmd, nr_bvec, pos);
if (unlikely(ret))
return ret;
if (cmd->bvec) {
offset = 0;
bvec = cmd->bvec;
iov_iter_bvec(&iter, rw, cmd->bvec, nr_bvec, blk_rq_bytes(rq));
iter.iov_offset = 0;
} else {
struct bio *bio = rq->bio;
struct bio_vec *bvec = __bvec_iter_bvec(bio->bi_io_vec,
bio->bi_iter);
/*
* 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, nr_bvec, blk_rq_bytes(rq));
iter.iov_offset = 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;
if (rw == ITER_SOURCE) {
kiocb_start_write(&cmd->iocb);
@ -433,7 +427,20 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
ret = file->f_op->read_iter(&cmd->iocb, &iter);
lo_rw_aio_do_completion(cmd);
return ret;
}
static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
loff_t pos, int rw)
{
int nr_bvec = lo_cmd_nr_bvec(cmd);
int ret;
ret = lo_rw_aio_prep(lo, cmd, nr_bvec, pos);
if (unlikely(ret))
return ret;
ret = lo_submit_rw_aio(lo, cmd, nr_bvec, rw);
if (ret != -EIOCBQUEUED)
lo_rw_aio_complete(&cmd->iocb, ret);
return -EIOCBQUEUED;