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ublk: use rq_for_each_segment() for user copy 

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>
pull/1354/merge
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, .report_zones = ublk_report_zones,
}; };
struct ublk_io_iter { /*
struct bio *bio; * Copy data between request pages and io_iter, and 'offset'
struct bvec_iter iter; * is the start point of linear offset of request.
}; */
static size_t ublk_copy_user_pages(const struct request *req,
/* return how many bytes are copied */ unsigned offset, struct iov_iter *uiter, int dir)
static size_t ublk_copy_io_pages(struct ublk_io_iter *data,
struct iov_iter *uiter, int dir)
{ {
struct req_iterator iter;
struct bio_vec bv;
size_t done = 0; size_t done = 0;
for (;;) { rq_for_each_segment(bv, req, iter) {
struct bio_vec bv = bio_iter_iovec(data->bio, data->iter); void *bv_buf;
void *bv_buf = bvec_kmap_local(&bv);
size_t copied; 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) if (dir == ITER_DEST)
copied = copy_to_iter(bv_buf, bv.bv_len, uiter); copied = copy_to_iter(bv_buf, bv.bv_len, uiter);
else else
@ -940,50 +947,11 @@ static size_t ublk_copy_io_pages(struct ublk_io_iter *data,
if (copied < bv.bv_len) if (copied < bv.bv_len)
break; break;
/* advance bio */ offset = 0;
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;
}
} }
return done; 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) static inline bool ublk_need_map_req(const struct request *req)
{ {
return ublk_rq_has_data(req) && req_op(req) == REQ_OP_WRITE; return ublk_rq_has_data(req) && req_op(req) == REQ_OP_WRITE;