block: add a poll_fn callback to struct request_queue

That we we can also poll non blk-mq queues.  Mostly needed for
the NVMe multipath code, but could also be useful elsewhere.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 5 insertions, 9 deletions

diff --git a/block/blk-mq.c b/block/blk-mq.c
index e4d2490f4e7e..95ea5889b825 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -37,6 +37,7 @@
 #include "blk-wbt.h"
 #include "blk-mq-sched.h"
 
+static bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie);
 static void blk_mq_poll_stats_start(struct request_queue *q);
 static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb);
 
@@ -2499,6 +2500,8 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
         spin_lock_init(&q->requeue_lock);
 
         blk_queue_make_request(q, blk_mq_make_request);
+        if (q->mq_ops->poll)
+                q->poll_fn = blk_mq_poll;
 
         /*
          * Do this after blk_queue_make_request() overrides it...
@@ -2961,20 +2964,14 @@ static bool __blk_mq_poll(struct blk_mq_hw_ctx *hctx, struct request *rq)
         return false;
 }
 
-bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie)
+static bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie)
 {
         struct blk_mq_hw_ctx *hctx;
-        struct blk_plug *plug;
         struct request *rq;
 
-        if (!q->mq_ops || !q->mq_ops->poll || !blk_qc_t_valid(cookie) ||
-            !test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
+        if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
                 return false;
 
-        plug = current->plug;
-        if (plug)
-                blk_flush_plug_list(plug, false);
-
         hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)];
         if (!blk_qc_t_is_internal(cookie))
                 rq = blk_mq_tag_to_rq(hctx->tags, blk_qc_t_to_tag(cookie));
@@ -2992,7 +2989,6 @@ bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie)
 
         return __blk_mq_poll(hctx, rq);
 }
-EXPORT_SYMBOL_GPL(blk_mq_poll);
 
 static int __init blk_mq_init(void)
 {