[SRU][F][PATCH 1/6] blk-mq: blk-mq: provide forced completion method

[Matthew Ruffell]

From: Keith Busch <kbusch at kernel.org>

BugLink: https://bugs.launchpad.net/bugs/1896350

Drivers may need to bypass error injection for error recovery. Rename
__blk_mq_complete_request() to blk_mq_force_complete_rq() and export
that function so drivers may skip potential fake timeouts after they've
reclaimed lost requests.

Signed-off-by: Keith Busch <kbusch at kernel.org>
Reviewed-by: Daniel Wagner <dwagner at suse.de>
Signed-off-by: Jens Axboe <axboe at kernel.dk>
(cherry picked from commit 7b11eab041dacfeaaa6d27d9183b247a995bc16d)
Signed-off-by: Matthew Ruffell <matthew.ruffell at canonical.com>
---
 block/blk-mq.c         | 15 +++++++++++++--
 include/linux/blk-mq.h |  1 +
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 84798d09ca46..82e93cd9f60d 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -579,7 +579,17 @@ static void __blk_mq_complete_request_remote(void *data)
 	q->mq_ops->complete(rq);
 }
 
-static void __blk_mq_complete_request(struct request *rq)
+/**
+ * blk_mq_force_complete_rq() - Force complete the request, bypassing any error
+ * 				injection that could drop the completion.
+ * @rq: Request to be force completed
+ *
+ * Drivers should use blk_mq_complete_request() to complete requests in their
+ * normal IO path. For timeout error recovery, drivers may call this forced
+ * completion routine after they've reclaimed timed out requests to bypass
+ * potentially subsequent fake timeouts.
+ */
+void blk_mq_force_complete_rq(struct request *rq)
 {
 	struct blk_mq_ctx *ctx = rq->mq_ctx;
 	struct request_queue *q = rq->q;
@@ -625,6 +635,7 @@ static void __blk_mq_complete_request(struct request *rq)
 	}
 	put_cpu();
 }
+EXPORT_SYMBOL_GPL(blk_mq_force_complete_rq);
 
 static void hctx_unlock(struct blk_mq_hw_ctx *hctx, int srcu_idx)
 	__releases(hctx->srcu)
@@ -658,7 +669,7 @@ bool blk_mq_complete_request(struct request *rq)
 {
 	if (unlikely(blk_should_fake_timeout(rq->q)))
 		return false;
-	__blk_mq_complete_request(rq);
+	blk_mq_force_complete_rq(rq);
 	return true;
 }
 EXPORT_SYMBOL(blk_mq_complete_request);
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 0bf056de5cc3..92b48a8e4af3 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -312,6 +312,7 @@ void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list);
 void blk_mq_kick_requeue_list(struct request_queue *q);
 void blk_mq_delay_kick_requeue_list(struct request_queue *q, unsigned long msecs);
 bool blk_mq_complete_request(struct request *rq);
+void blk_mq_force_complete_rq(struct request *rq);
 bool blk_mq_bio_list_merge(struct request_queue *q, struct list_head *list,
 			   struct bio *bio, unsigned int nr_segs);
 bool blk_mq_queue_stopped(struct request_queue *q);
-- 
2.34.1