From f4560ffe8cec1361b1021d81aca6a4173f8e7c87 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Sun, 18 Jun 2017 14:24:27 -0600 Subject: blk-mq: use QUEUE_FLAG_QUIESCED to quiesce queue It is required that no dispatch can happen any more once blk_mq_quiesce_queue() returns, and we don't have such requirement on APIs of stopping queue. But blk_mq_quiesce_queue() still may not block/drain dispatch in the the case of BLK_MQ_S_START_ON_RUN, so use the new introduced flag of QUEUE_FLAG_QUIESCED and evaluate it inside RCU read-side critical sections for fixing this issue. Also blk_mq_quiesce_queue() is implemented via stopping queue, which limits its uses, and easy to cause race, because any queue restart in other paths may break blk_mq_quiesce_queue(). With the introduced flag of QUEUE_FLAG_QUIESCED, we don't need to depend on stopping queue for quiescing any more. Signed-off-by: Ming Lei Reviewed-by: Bart Van Assche Signed-off-by: Jens Axboe --- include/linux/blkdev.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/blkdev.h') diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 8423f6baf818..22cfba64ce81 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -619,6 +619,7 @@ struct request_queue { #define QUEUE_FLAG_POLL_STATS 28 /* collecting stats for hybrid polling */ #define QUEUE_FLAG_REGISTERED 29 /* queue has been registered to a disk */ #define QUEUE_FLAG_SCSI_PASSTHROUGH 30 /* queue supports SCSI commands */ +#define QUEUE_FLAG_QUIESCED 31 /* queue has been quiesced */ #define QUEUE_FLAG_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \ (1 << QUEUE_FLAG_STACKABLE) | \ @@ -715,6 +716,7 @@ static inline void queue_flag_clear(unsigned int flag, struct request_queue *q) #define blk_noretry_request(rq) \ ((rq)->cmd_flags & (REQ_FAILFAST_DEV|REQ_FAILFAST_TRANSPORT| \ REQ_FAILFAST_DRIVER)) +#define blk_queue_quiesced(q) test_bit(QUEUE_FLAG_QUIESCED, &(q)->queue_flags) static inline bool blk_account_rq(struct request *rq) { -- cgit v1.2.3