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ublk: use rq_for_each_segment() for user copy

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ublk_advance_io_iter() and ublk_copy_io_pages() currently open-code the
iteration over the request's bvecs. Switch to the rq_for_each_segment()
macro provided by blk-mq to avoid reaching into the bio internals and
simplify the code.

Suggested-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Caleb Sander Mateos
2025-11-06 10:16:47 -07:00
committed by Jens Axboe
parent 2299ceec36
commit e87d66ab27
1 changed files with 19 additions and 51 deletions
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70
drivers/block/ublk_drv.c
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@@ -913,22 +913,29 @@ static const struct block_device_operations ub_fops = {
.report_zones = ublk_report_zones,
};
struct ublk_io_iter {
struct bio *bio;
struct bvec_iter iter;
};
/* return how many bytes are copied */
static size_t ublk_copy_io_pages(struct ublk_io_iter *data,
struct iov_iter *uiter, int dir)
/*
* Copy data between request pages and io_iter, and 'offset'
* is the start point of linear offset of request.
*/
static size_t ublk_copy_user_pages(const struct request *req,
unsigned offset, struct iov_iter *uiter, int dir)
{
struct req_iterator iter;
struct bio_vec bv;
size_t done = 0;
for (;;) {
struct bio_vec bv = bio_iter_iovec(data->bio, data->iter);
void *bv_buf = bvec_kmap_local(&bv);
rq_for_each_segment(bv, req, iter) {
void *bv_buf;
size_t copied;
if (offset >= bv.bv_len) {
offset -= bv.bv_len;
continue;
}
bv.bv_offset += offset;
bv.bv_len -= offset;
bv_buf = bvec_kmap_local(&bv);
if (dir == ITER_DEST)
copied = copy_to_iter(bv_buf, bv.bv_len, uiter);
else
@@ -940,50 +947,11 @@ static size_t ublk_copy_io_pages(struct ublk_io_iter *data,
if (copied < bv.bv_len)
break;
/* advance bio */
bio_advance_iter_single(data->bio, &data->iter, copied);
if (!data->iter.bi_size) {
data->bio = data->bio->bi_next;
if (data->bio == NULL)
break;
data->iter = data->bio->bi_iter;
}
offset = 0;
}
return done;
}
static bool ublk_advance_io_iter(const struct request *req,
struct ublk_io_iter *iter, unsigned int offset)
{
struct bio *bio = req->bio;
for_each_bio(bio) {
if (bio->bi_iter.bi_size > offset) {
iter->bio = bio;
iter->iter = bio->bi_iter;
bio_advance_iter(iter->bio, &iter->iter, offset);
return true;
}
offset -= bio->bi_iter.bi_size;
}
return false;
}
/*
* Copy data between request pages and io_iter, and 'offset'
* is the start point of linear offset of request.
*/
static size_t ublk_copy_user_pages(const struct request *req,
unsigned offset, struct iov_iter *uiter, int dir)
{
struct ublk_io_iter iter;
if (!ublk_advance_io_iter(req, &iter, offset))
return 0;
return ublk_copy_io_pages(&iter, uiter, dir);
}
static inline bool ublk_need_map_req(const struct request *req)
{
return ublk_rq_has_data(req) && req_op(req) == REQ_OP_WRITE;