Re: [PATCH v3 05/19] ublk: add ublk_copy_user_bvec() helper

On Mon, Jan 05, 2026 at 05:57:37PM -0700, Caleb Sander Mateos wrote:

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 2b0a9720921d..2ce9afdecc15 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -1000,10 +1000,39 @@ 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(const 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, @@ -1012,33 +1041,12 @@ 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;

}

Reviewed-by: Ming Lei ming.lei@redhat.com

Thanks, Ming