blk-mq: add tagset quiesce interface

Drivers that have shared tagsets may need to quiesce potentially a lot
of request queues that all share a single tagset (e.g. nvme). Add an
interface to quiesce all the queues on a given tagset. This interface is
useful because it can speedup the quiesce by doing it in parallel.

Because some queues should not need to be quiesced (e.g. the nvme
connect_q) when quiescing the tagset, introduce a
QUEUE_FLAG_SKIP_TAGSET_QUIESCE flag to allow this new interface to
ski quiescing a particular queue.

Signed-off-by: Chao Leng <lengchao@huawei.com>
[hch: simplify for the per-tag_set srcu_struct]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Chao Leng <lengchao@huawei.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20221101150050.3510-14-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index b7abfda..bae6f81 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -315,6 +315,33 @@ void blk_mq_unquiesce_queue(struct request_queue *q)
 }
 EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue);
 
+void blk_mq_quiesce_tagset(struct blk_mq_tag_set *set)
+{
+       struct request_queue *q;
+
+       mutex_lock(&set->tag_list_lock);
+       list_for_each_entry(q, &set->tag_list, tag_set_list) {
+               if (!blk_queue_skip_tagset_quiesce(q))
+                       blk_mq_quiesce_queue_nowait(q);
+       }
+       blk_mq_wait_quiesce_done(set);
+       mutex_unlock(&set->tag_list_lock);
+}
+EXPORT_SYMBOL_GPL(blk_mq_quiesce_tagset);
+
+void blk_mq_unquiesce_tagset(struct blk_mq_tag_set *set)
+{
+       struct request_queue *q;
+
+       mutex_lock(&set->tag_list_lock);
+       list_for_each_entry(q, &set->tag_list, tag_set_list) {
+               if (!blk_queue_skip_tagset_quiesce(q))
+                       blk_mq_unquiesce_queue(q);
+       }
+       mutex_unlock(&set->tag_list_lock);
+}
+EXPORT_SYMBOL_GPL(blk_mq_unquiesce_tagset);
+
 void blk_mq_wake_waiters(struct request_queue *q)
 {
        struct blk_mq_hw_ctx *hctx;

diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 061ea6e..109a0e3 100644 (file)
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -881,6 +881,8 @@ void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx *hctx, bool async);
 void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async);
 void blk_mq_quiesce_queue(struct request_queue *q);
 void blk_mq_wait_quiesce_done(struct blk_mq_tag_set *set);
+void blk_mq_quiesce_tagset(struct blk_mq_tag_set *set);
+void blk_mq_unquiesce_tagset(struct blk_mq_tag_set *set);
 void blk_mq_unquiesce_queue(struct request_queue *q);
 void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs);
 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async);

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 6a6fa16..9188aa3 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -571,6 +571,7 @@ struct request_queue {
 #define QUEUE_FLAG_HCTX_ACTIVE 28      /* at least one blk-mq hctx is active */
 #define QUEUE_FLAG_NOWAIT       29     /* device supports NOWAIT */
 #define QUEUE_FLAG_SQ_SCHED     30     /* single queue style io dispatch */
+#define QUEUE_FLAG_SKIP_TAGSET_QUIESCE 31 /* quiesce_tagset skip the queue*/
 
 #define QUEUE_FLAG_MQ_DEFAULT  ((1UL << QUEUE_FLAG_IO_STAT) |          \
                                 (1UL << QUEUE_FLAG_SAME_COMP) |        \
@@ -610,6 +611,8 @@ bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q);
 #define blk_queue_pm_only(q)   atomic_read(&(q)->pm_only)
 #define blk_queue_registered(q)        test_bit(QUEUE_FLAG_REGISTERED, &(q)->queue_flags)
 #define blk_queue_sq_sched(q)  test_bit(QUEUE_FLAG_SQ_SCHED, &(q)->queue_flags)
+#define blk_queue_skip_tagset_quiesce(q) \
+       test_bit(QUEUE_FLAG_SKIP_TAGSET_QUIESCE, &(q)->queue_flags)
 
 extern void blk_set_pm_only(struct request_queue *q);
 extern void blk_clear_pm_only(struct request_queue *q);