block: allow blk_rq_map_kern to append to requests

Use blk_rq_append_bio() internally instead of blk_rq_bio_prep()
so blk_rq_map_kern can be called multiple times, to map multiple
buffers.

This is in the effort to un-export blk_rq_append_bio()

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 10 insertions, 2 deletions

diff --git a/block/blk-map.c b/block/blk-map.c
index 56082bea4504..caa05a667743 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -282,7 +282,8 @@ EXPORT_SYMBOL(blk_rq_unmap_user);
  *
  * Description:
  *    Data will be mapped directly if possible. Otherwise a bounce
- *    buffer is used.
+ *    buffer is used. Can be called multple times to append multple
+ *    buffers.
  */
 int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
                     unsigned int len, gfp_t gfp_mask)
@@ -290,6 +291,7 @@ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
         int reading = rq_data_dir(rq) == READ;
         int do_copy = 0;
         struct bio *bio;
+        int ret;
 
         if (len > (q->max_hw_sectors << 9))
                 return -EINVAL;
@@ -311,7 +313,13 @@ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
         if (do_copy)
                 rq->cmd_flags |= REQ_COPY_USER;
 
-        blk_rq_bio_prep(q, rq, bio);
+        ret = blk_rq_append_bio(q, rq, bio);
+        if (unlikely(ret)) {
+                /* request is too big */
+                bio_put(bio);
+                return ret;
+        }
+
         blk_queue_bounce(q, &rq->bio);
         rq->buffer = NULL;
         return 0;