diff mbox series

[RESEND,v2,3/3] block: hide back blk_freeze_queue_start and export its blk-mq alias

Message ID 3f2b51cc7f5c21e49bfa089e594cb203a4015183.1667107410.git.nickyc975@zju.edu.cn (mailing list archive)
State Rejected, archived
Headers show
Series queue freezing improvement and cleanups | expand

Commit Message

Jinlong Chen Oct. 30, 2022, 5:26 a.m. UTC 
blk_freeze_queue_start is used internally for universal queue draining and
externally for blk-mq specific queue freezing. Keep the non-blk-mq name
private and export a blk-mq alias to users.

Signed-off-by: Jinlong Chen <nickyc975@zju.edu.cn>
---
 block/blk-core.c              | 13 +++++++++++++
 block/blk-mq.c                | 27 ++++++++++++++-------------
 block/blk-pm.c                |  2 +-
 block/blk.h                   |  1 +
 drivers/nvme/host/core.c      |  2 +-
 drivers/nvme/host/multipath.c |  2 +-
 include/linux/blk-mq.h        |  2 +-
 7 files changed, 32 insertions(+), 17 deletions(-)

Comments

Christoph Hellwig Oct. 30, 2022, 7:40 a.m. UTC | #1 
On Sun, Oct 30, 2022 at 01:26:46PM +0800, Jinlong Chen wrote:
> blk_freeze_queue_start is used internally for universal queue draining and
> externally for blk-mq specific queue freezing. Keep the non-blk-mq name
> private and export a blk-mq alias to users.

I really don't see the point here.  Eventually all of the freezing
should move out of the mq namespace.  But that given that we have
actual technical work pending here I'd suggest to just leave it alone
for now, and just respin a version of patch 1 without the pointless
comment.
Jinlong Chen Oct. 30, 2022, 8:19 a.m. UTC | #2 
> On Sun, Oct 30, 2022 at 01:26:46PM +0800, Jinlong Chen wrote:
> > blk_freeze_queue_start is used internally for universal queue draining and
> > externally for blk-mq specific queue freezing. Keep the non-blk-mq name
> > private and export a blk-mq alias to users.
> 
> I really don't see the point here.  Eventually all of the freezing
> should move out of the mq namespace.  But that given that we have
> actual technical work pending here I'd suggest to just leave it alone
> for now, and just respin a version of patch 1 without the pointless
> comment.

I agree that the freezing stuff (maybe also the quiescing stuff) should
move out of the mq namespace. If now is not the proper time, I'll leave
them alone. I'll resend patch 1 alone without the comment.

Thanks!
Jinlong Chen
Christoph Hellwig Oct. 30, 2022, 8:21 a.m. UTC | #3 
On Sun, Oct 30, 2022 at 04:19:49PM +0800, Jinlong Chen wrote:
> I agree that the freezing stuff (maybe also the quiescing stuff) should
> move out of the mq namespace. If now is not the proper time, I'll leave
> them alone. I'll resend patch 1 alone without the comment.

The quiesce actually is entirely blk-mq specific, which just have some
careless callers.
Jinlong Chen Oct. 30, 2022, 8:35 a.m. UTC | #4 
> > I agree that the freezing stuff (maybe also the quiescing stuff) should
> > move out of the mq namespace. If now is not the proper time, I'll leave
> > them alone. I'll resend patch 1 alone without the comment.
> 
> The quiesce actually is entirely blk-mq specific, which just have some
> careless callers.

Got it, thank you!

Thanks!
Jinlong Chen
diff mbox series

Patch

diff --git a/block/blk-core.c b/block/blk-core.c
index 5d50dd16e2a5..d3dd439a8ed4 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -269,6 +269,19 @@  void blk_put_queue(struct request_queue *q)
 }
 EXPORT_SYMBOL(blk_put_queue);
 
+void blk_freeze_queue_start(struct request_queue *q)
+{
+	mutex_lock(&q->mq_freeze_lock);
+	if (++q->mq_freeze_depth == 1) {
+		percpu_ref_kill(&q->q_usage_counter);
+		mutex_unlock(&q->mq_freeze_lock);
+		if (queue_is_mq(q))
+			blk_mq_run_hw_queues(q, false);
+	} else {
+		mutex_unlock(&q->mq_freeze_lock);
+	}
+}
+
 void blk_queue_start_drain(struct request_queue *q)
 {
 	/*
diff --git a/block/blk-mq.c b/block/blk-mq.c
index e0654a2e80b9..d638bd0fb4d8 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -161,19 +161,20 @@  void blk_mq_in_flight_rw(struct request_queue *q, struct block_device *part,
 	inflight[1] = mi.inflight[1];
 }
 
-void blk_freeze_queue_start(struct request_queue *q)
+void blk_mq_freeze_queue_start(struct request_queue *q)
 {
-	mutex_lock(&q->mq_freeze_lock);
-	if (++q->mq_freeze_depth == 1) {
-		percpu_ref_kill(&q->q_usage_counter);
-		mutex_unlock(&q->mq_freeze_lock);
-		if (queue_is_mq(q))
-			blk_mq_run_hw_queues(q, false);
-	} else {
-		mutex_unlock(&q->mq_freeze_lock);
-	}
+	/*
+	 * Warn on non-blk-mq usages.
+	 */
+	WARN_ON_ONCE(!queue_is_mq(q));
+
+	/*
+	 * Just an alias of blk_freeze_queue_start to keep the consistency of the
+	 * blk_mq_* namespace.
+	 */
+	blk_freeze_queue_start(q);
 }
-EXPORT_SYMBOL_GPL(blk_freeze_queue_start);
+EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_start);
 
 void blk_mq_freeze_queue_wait(struct request_queue *q)
 {
@@ -196,7 +197,7 @@  EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout);
  */
 void blk_mq_freeze_queue(struct request_queue *q)
 {
-	blk_freeze_queue_start(q);
+	blk_mq_freeze_queue_start(q);
 	blk_mq_freeze_queue_wait(q);
 }
 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
@@ -1570,7 +1571,7 @@  static void blk_mq_timeout_work(struct work_struct *work)
 	 * percpu_ref_tryget directly, because we need to be able to
 	 * obtain a reference even in the short window between the queue
 	 * starting to freeze, by dropping the first reference in
-	 * blk_freeze_queue_start, and the moment the last request is
+	 * blk_mq_freeze_queue_start, and the moment the last request is
 	 * consumed, marked by the instant q_usage_counter reaches
 	 * zero.
 	 */
diff --git a/block/blk-pm.c b/block/blk-pm.c
index 2dad62cc1572..ae2b950ed45d 100644
--- a/block/blk-pm.c
+++ b/block/blk-pm.c
@@ -80,7 +80,7 @@  int blk_pre_runtime_suspend(struct request_queue *q)
 	blk_set_pm_only(q);
 	ret = -EBUSY;
 	/* Switch q_usage_counter from per-cpu to atomic mode. */
-	blk_freeze_queue_start(q);
+	blk_mq_freeze_queue_start(q);
 	/*
 	 * Wait until atomic mode has been reached. Since that
 	 * involves calling call_rcu(), it is guaranteed that later
diff --git a/block/blk.h b/block/blk.h
index e9addea2838a..ee576bb74382 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -37,6 +37,7 @@  struct blk_flush_queue *blk_alloc_flush_queue(int node, int cmd_size,
 					      gfp_t flags);
 void blk_free_flush_queue(struct blk_flush_queue *q);
 
+void blk_freeze_queue_start(struct request_queue *q);
 void __blk_mq_unfreeze_queue(struct request_queue *q, bool force_atomic);
 void blk_queue_start_drain(struct request_queue *q);
 int __bio_queue_enter(struct request_queue *q, struct bio *bio);
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 0090dc0b3ae6..e2d5c54c651a 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -5199,7 +5199,7 @@  void nvme_start_freeze(struct nvme_ctrl *ctrl)
 
 	down_read(&ctrl->namespaces_rwsem);
 	list_for_each_entry(ns, &ctrl->namespaces, list)
-		blk_freeze_queue_start(ns->queue);
+		blk_mq_freeze_queue_start(ns->queue);
 	up_read(&ctrl->namespaces_rwsem);
 }
 EXPORT_SYMBOL_GPL(nvme_start_freeze);
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index 0ea7e441e080..3bb358bd0cde 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -77,7 +77,7 @@  void nvme_mpath_start_freeze(struct nvme_subsystem *subsys)
 	lockdep_assert_held(&subsys->lock);
 	list_for_each_entry(h, &subsys->nsheads, entry)
 		if (h->disk)
-			blk_freeze_queue_start(h->disk->queue);
+			blk_mq_freeze_queue_start(h->disk->queue);
 }
 
 void nvme_failover_req(struct request *req)
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 569053ed959d..8600d4b4aa80 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -887,7 +887,7 @@  void blk_mq_tagset_busy_iter(struct blk_mq_tag_set *tagset,
 void blk_mq_tagset_wait_completed_request(struct blk_mq_tag_set *tagset);
 void blk_mq_freeze_queue(struct request_queue *q);
 void blk_mq_unfreeze_queue(struct request_queue *q);
-void blk_freeze_queue_start(struct request_queue *q);
+void blk_mq_freeze_queue_start(struct request_queue *q);
 void blk_mq_freeze_queue_wait(struct request_queue *q);
 int blk_mq_freeze_queue_wait_timeout(struct request_queue *q,
 				     unsigned long timeout);