Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6

1 files changed, 14 insertions, 1 deletions

diff --git a/block/blk-merge.c b/block/blk-merge.c
index d3b84bbb776a..b5c5c4a9e3f0 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -220,7 +220,19 @@ new_segment:
                 bvprv = bvec;
         } /* segments in rq */
 
-        if (q->dma_drain_size) {
+
+        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);
+
                 sg->page_link &= ~0x02;
                 sg = sg_next(sg);
                 sg_set_page(sg, virt_to_page(q->dma_drain_buffer),
@@ -228,6 +240,7 @@ new_segment:
                             ((unsigned long)q->dma_drain_buffer) &
                             (PAGE_SIZE - 1));
                 nsegs++;
+                rq->extra_len += q->dma_drain_size;
         }
 
         if (sg)