[PATCH 08/20] ublk: add ublk_copy_user_bvec() helper

Caleb Sander Mateos
2025-12-17T05:35:16Z

Factor a helper function ublk_copy_user_bvec() out of
ublk_copy_user_pages(). It will be used for copying integrity data too.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
---
drivers/block/ublk_drv.c | 52 +++++++++++++++++++++++-----------------
1 file changed, 30 insertions(+), 22 deletions(-)

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index d3652ceba96d..0499add560b5 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -987,10 +987,39 @@ static const struct block_device_operations ub_fops = {
.open = ublk_open,
.free_disk = ublk_free_disk,
.report_zones = ublk_report_zones,
};

+static bool ublk_copy_user_bvec(struct bio_vec bv, unsigned *offset,
+ struct iov_iter *uiter, int dir, size_t *done)
+{
+ unsigned len;
+ void *bv_buf;
+ size_t copied;
+
+ if (*offset >= bv.bv_len) {
+ *offset -= bv.bv_len;
+ return true;
+ }
+
+ len = bv.bv_len - *offset;
+ bv_buf = kmap_local_page(bv.bv_page) + bv.bv_offset + *offset;
+ if (dir == ITER_DEST)
+ copied = copy_to_iter(bv_buf, len, uiter);
+ else
+ copied = copy_from_iter(bv_buf, len, uiter);
+
+ kunmap_local(bv_buf);
+
+ *done += copied;
+ if (copied < len)
+ return false;
+
+ *offset = 0;
+ return true;
+}
+
/*
* 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,
@@ -999,33 +1028,12 @@ static size_t ublk_copy_user_pages(const struct request *req,
struct req_iterator iter;
struct bio_vec bv;
size_t done = 0;

rq_for_each_segment(bv, req, iter) {
- unsigned len;
- void *bv_buf;
- size_t copied;
-
- if (offset >= bv.bv_len) {
- offset -= bv.bv_len;
- continue;
- }
-
- len = bv.bv_len - offset;
- bv_buf = kmap_local_page(bv.bv_page) + bv.bv_offset + offset;
- if (dir == ITER_DEST)
- copied = copy_to_iter(bv_buf, len, uiter);
- else
- copied = copy_from_iter(bv_buf, len, uiter);
-
- kunmap_local(bv_buf);
-
- done += copied;
- if (copied < len)
+ if (!ublk_copy_user_bvec(bv, &offset, uiter, dir, &done))
break;
-
- offset = 0;
}
return done;
}

static inline bool ublk_need_map_req(const struct request *req)
--
2.45.2