[PATCH V5 13/16] block: ublk_drv: support to copy any part of request pages

Ming Lei
2023-03-28T15:29:05Z

Add 'offset' to 'struct ublk_map_data', so that ublk_copy_user_pages()
can be used to copy any sub-buffer(linear mapped) of the request.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
drivers/block/ublk_drv.c | 31 ++++++++++++++++++++++++-------
1 file changed, 24 insertions(+), 7 deletions(-)

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 0dc8eb04b9a5..32304942ab87 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -511,19 +511,36 @@ static void ublk_copy_io_pages(struct ublk_io_iter *data,
}
}

+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,
- struct iov_iter *uiter, int dir)
+ unsigned offset, struct iov_iter *uiter, int dir)
{
- struct ublk_io_iter iter = {
- .bio = req->bio,
- .iter = req->bio->bi_iter,
- };
+ struct ublk_io_iter iter;
size_t done = 0;

+ if (!ublk_advance_io_iter(req, &iter, offset))
+ return 0;
+
while (iov_iter_count(uiter) && iter.bio) {
unsigned nr_pages;
size_t len, off;
@@ -576,7 +593,7 @@ static int ublk_map_io(const struct ublk_queue *ubq, const struct request *req,
import_single_range(dir, u64_to_user_ptr(io->addr), rq_bytes,
&iov, &iter);

- return ublk_copy_user_pages(req, &iter, dir);
+ return ublk_copy_user_pages(req, 0, &iter, dir);
}
return rq_bytes;
}
@@ -596,7 +613,7 @@ static int ublk_unmap_io(const struct ublk_queue *ubq,

import_single_range(dir, u64_to_user_ptr(io->addr), io->res,
&iov, &iter);
- return ublk_copy_user_pages(req, &iter, dir);
+ return ublk_copy_user_pages(req, 0, &iter, dir);
}
return rq_bytes;
}
--
2.39.2