block: don't honor chunk sizes for data-less IO
We don't need to honor chunk sizes for IO that doesn't carry any
data.
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 9ded80d..ccaa9aec 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -903,7 +903,7 @@
if (unlikely(rq->cmd_type == REQ_TYPE_BLOCK_PC))
return q->limits.max_hw_sectors;
- if (!q->limits.chunk_sectors)
+ if (!q->limits.chunk_sectors || (rq->cmd_flags & REQ_DISCARD))
return blk_queue_get_max_sectors(q, rq->cmd_flags);
return min(blk_max_size_offset(q, blk_rq_pos(rq)),