block: remove dead struc request->completion_data field

It's no longer used. While in there, also update the comment as to why
it can coexist with the rb_node.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 2b7fb8e87793caa7d1a7cf6b5be972ed2d959a2b..b96e00499f9eee3eaa8bc2757bd7c096ce4d86a0 100644 (file)
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -158,13 +158,13 @@ struct request {
 
        /*
         * The rb_node is only used inside the io scheduler, requests
-        * are pruned when moved to the dispatch queue. So let the
-        * completion_data share space with the rb_node.
+        * are pruned when moved to the dispatch queue. special_vec must
+        * only be used if RQF_SPECIAL_PAYLOAD is set, and those cannot be
+        * insert into an IO scheduler.
         */
        union {
                struct rb_node rb_node; /* sort/lookup */
                struct bio_vec special_vec;
-               void *completion_data;
        };
 
        /*