[BLOCK] Clear sg entry before filling in blk_rq_map_sg()

The memset() of the sg entry was originally removed, because it could
overwrite a chain pointer. But it's quite OK to memset() it when we know
it's a valid entry, since it can't contain a chain pointer.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 9eabac95fbe0..1014d349a386 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -1352,6 +1352,7 @@ new_segment:
                         sg = next_sg;
                         next_sg = sg_next(sg);
 
+                        memset(sg, 0, sizeof(*sg));
                         sg->page = bvec->bv_page;
                         sg->length = nbytes;
                         sg->offset = bvec->bv_offset;