4 files changed, 17 insertions, 20 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);
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index f6980bd9d8f9..12d69d7c8577 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -852,7 +852,7 @@ void scsi_finish_command(struct scsi_cmnd *cmd)
                                 "Notifying upper driver of completion "
                                 "(result %x)\n", cmd->result));
 
-        good_bytes = scsi_bufflen(cmd) + cmd->request->extra_len;
+        good_bytes = scsi_bufflen(cmd);
         if (cmd->request->cmd_type != REQ_TYPE_BLOCK_PC) {
                 drv = scsi_cmd_to_driver(cmd);
                 if (drv->done)
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 6f79d40dd3c0..b3a58adc4352 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -112,6 +112,7 @@ enum rq_flag_bits {
         __REQ_RW_SYNC,          /* request is sync (O_DIRECT) */
         __REQ_ALLOCED,          /* request came from our alloc pool */
         __REQ_RW_META,          /* metadata io request */
+        __REQ_COPY_USER,        /* contains copies of user pages */
         __REQ_NR_BITS,          /* stops here */
 };
 
@@ -133,6 +134,7 @@ enum rq_flag_bits {
 #define REQ_RW_SYNC     (1 << __REQ_RW_SYNC)
 #define REQ_ALLOCED     (1 << __REQ_ALLOCED)
 #define REQ_RW_META     (1 << __REQ_RW_META)
+#define REQ_COPY_USER   (1 << __REQ_COPY_USER)
 
 #define BLK_MAX_CDB     16