blk_discard_mergable  712 block/blk-merge.c 	if (blk_discard_mergable(req))
blk_discard_mergable  798 block/blk-merge.c 	if (!blk_discard_mergable(req))
blk_discard_mergable  888 block/blk-merge.c 	if (blk_discard_mergable(rq))