alinux: blk-mq: remove QUEUE_FLAG_POLL from default MQ flags

fix #28528017

In case of virtio-blk device, checking /sys/block/<device>/queue/io_poll
will show 1 and user can't disable it. Actually virtio-blk doesn't
support poll yet, so it will confuse end user. The root cause is mq
initialization will default set bit QUEUE_FLAG_POLL.

This fix takes ideas from the following upstream commits:
6544d229bf43 ("block: enable polling by default if a poll map is initalized")
6e0de61107f0 ("blk-mq: remove QUEUE_FLAG_POLL from default MQ flags")
Since we don't want to get HCTX_TYPE_POLL related logic involved, so
just check mq_ops->poll and then set QUEUE_FLAG_POLL.
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>

block/blk-mq.c

@@ -2707,6 +2707,8 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
 	q->nr_queues = nr_cpu_ids;
 
 	q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
+	if (q->mq_ops->poll)
+		queue_flag_set_unlocked(QUEUE_FLAG_POLL, q);
 
 	if (!(set->flags & BLK_MQ_F_SG_MERGE))
 		queue_flag_set_unlocked(QUEUE_FLAG_NO_SG_MERGE, q);

include/linux/blkdev.h

@@ -728,8 +728,7 @@ struct request_queue {
 				 (1 << QUEUE_FLAG_ADD_RANDOM))
 
 #define QUEUE_FLAG_MQ_DEFAULT	((1 << QUEUE_FLAG_IO_STAT) |		\
-				 (1 << QUEUE_FLAG_SAME_COMP)	|	\
-				 (1 << QUEUE_FLAG_POLL))
+				 (1 << QUEUE_FLAG_SAME_COMP))
 
 void blk_queue_flag_set(unsigned int flag, struct request_queue *q);
 void blk_queue_flag_clear(unsigned int flag, struct request_queue *q);