[PATCH V2 4/7] block: don't check bio in blk_throtl_dispatch_work_fn

[Ming Lei <ming.lei@redhat.com>]

The bio has been checked already before throttling, so no need to check
it again before dispatching it from throttle queue.

Add one local helper of submit_bio_noacct_nocheck() for this purpose.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 block/blk-core.c     | 35 ++++++++++++++++++++++-------------
 block/blk-throttle.c |  2 +-
 block/blk.h          |  1 +
 3 files changed, 24 insertions(+), 14 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 1514dbab0bd8..4de9f391836b 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -876,20 +876,8 @@ static void __submit_bio_noacct_mq(struct bio *bio)
 	current->bio_list = NULL;
 }
 
-/**
- * submit_bio_noacct - re-submit a bio to the block device layer for I/O
- * @bio:  The bio describing the location in memory and on the device.
- *
- * This is a version of submit_bio() that shall only be used for I/O that is
- * resubmitted to lower level drivers by stacking block drivers.  All file
- * systems and other upper level users of the block layer should use
- * submit_bio() instead.
- */
-void submit_bio_noacct(struct bio *bio)
+static inline void __submit_bio_noacct_nocheck(struct bio *bio)
 {
-	if (unlikely(!submit_bio_checks(bio)))
-		return;
-
 	/*
 	 * We only want one ->submit_bio to be active at a time, else stack
 	 * usage with stacked devices could be a problem.  Use current->bio_list
@@ -903,8 +891,29 @@ void submit_bio_noacct(struct bio *bio)
 	else
 		__submit_bio_noacct(bio);
 }
+
+/**
+ * submit_bio_noacct - re-submit a bio to the block device layer for I/O
+ * @bio:  The bio describing the location in memory and on the device.
+ *
+ * This is a version of submit_bio() that shall only be used for I/O that is
+ * resubmitted to lower level drivers by stacking block drivers.  All file
+ * systems and other upper level users of the block layer should use
+ * submit_bio() instead.
+ */
+void submit_bio_noacct(struct bio *bio)
+{
+	if (unlikely(!submit_bio_checks(bio)))
+		return;
+	__submit_bio_noacct_nocheck(bio);
+}
 EXPORT_SYMBOL(submit_bio_noacct);
 
+void submit_bio_noacct_nocheck(struct bio *bio)
+{
+	__submit_bio_noacct_nocheck(bio);
+}
+
 /**
  * submit_bio - submit a bio to the block device layer for I/O
  * @bio: The &struct bio which describes the I/O
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 7c462c006b26..6cca1715c31e 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -1219,7 +1219,7 @@ static void blk_throtl_dispatch_work_fn(struct work_struct *work)
 	if (!bio_list_empty(&bio_list_on_stack)) {
 		blk_start_plug(&plug);
 		while ((bio = bio_list_pop(&bio_list_on_stack)))
-			submit_bio_noacct(bio);
+			submit_bio_noacct_nocheck(bio);
 		blk_finish_plug(&plug);
 	}
 }
diff --git a/block/blk.h b/block/blk.h
index b2516cb4f98e..ebaa59ca46ca 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -46,6 +46,7 @@ void blk_freeze_queue(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);
+void submit_bio_noacct_nocheck(struct bio *bio);
 
 static inline bool blk_try_enter_queue(struct request_queue *q, bool pm)
 {
-- 
2.31.1