2 files changed, 14 insertions, 19 deletions

diff --git a/block/blk-map.c b/block/blk-map.c
index ab43533ba641..3c942bd6422a 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -141,25 +141,8 @@ int blk_rq_map_user(struct request_queue *q, struct request *rq,
                 ubuf += ret;
         }
 
-        /*
-         * __blk_rq_map_user() copies the buffers if starting address
-         * or length isn't aligned to dma_pad_mask.  As the copied
-         * buffer is always page aligned, we know that there's enough
-         * room for padding.  Extend the last bio and update
-         * rq->data_len accordingly.
-         *
-         * On unmap, bio_uncopy_user() will use unmodified
-         * bio_map_data pointed to by bio->bi_private.
-         */
-        if (len & q->dma_pad_mask) {
-                unsigned int pad_len = (q->dma_pad_mask & ~len) + 1;
-                struct bio *tail = rq->biotail;
-
-                tail->bi_io_vec[tail->bi_vcnt - 1].bv_len += pad_len;
-                tail->bi_size += pad_len;
-
-                rq->extra_len += pad_len;
-        }
+        if (!bio_flagged(bio, BIO_USER_MAPPED))
+                rq->cmd_flags |= REQ_COPY_USER;
 
         rq->buffer = rq->data = NULL;
         return 0;
@@ -224,6 +207,9 @@ int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
                 return -EINVAL;
         }
 
+        if (!bio_flagged(bio, BIO_USER_MAPPED))
+                rq->cmd_flags |= REQ_COPY_USER;
+
         bio_get(bio);
         blk_rq_bio_prep(q, rq, bio);
         rq->buffer = rq->data = NULL;
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 0f58616bcd7f..b5c5c4a9e3f0 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -220,6 +220,15 @@ new_segment:
                 bvprv = bvec;
         } /* segments in rq */
 
+
+        if (unlikely(rq->cmd_flags & REQ_COPY_USER) &&
+            (rq->data_len & q->dma_pad_mask)) {
+                unsigned int pad_len = (q->dma_pad_mask & ~rq->data_len) + 1;
+
+                sg->length += pad_len;
+                rq->extra_len += pad_len;
+        }
+
         if (q->dma_drain_size && q->dma_drain_needed(rq)) {
                 if (rq->cmd_flags & REQ_RW)
                         memset(q->dma_drain_buffer, 0, q->dma_drain_size);