[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>

diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 9eabac95fbe053917cb25f7ba1e9fb208b8e94d1..1014d349a386b48385a75f0a98de7186d25df73d 100644 (file)
--- 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;