linux-kernel - [PATCH 1/2] completion: move blk_wait

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Message-ID: <31b118f3-bc8d-b18b-c4b9-e57d74a73f@redhat.com>
Date: Wed, 17 Apr 2024 19:49:17 +0200 (CEST)
From: Mikulas Patocka <mpatocka@...hat.com>
To: Mike Snitzer <msnitzer@...hat.com>, Jens Axboe <axboe@...nel.dk>, 
    Damien Le Moal <dlemoal@...nel.org>, Peter Zijlstra <peterz@...radead.org>, 
    Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>, 
    Waiman Long <longman@...hat.com>
cc: Guangwu Zhang <guazhang@...hat.com>, dm-devel@...ts.linux.dev, 
    linux-block@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] completion: move blk_wait_io to
 kernel/sched/completion.c

The block layer has a function blk_wait_io - it works like
wait_for_completion_io, except that it doesn't warn if the wait takes too
long. This commit renames the function to wait_for_completion_long_io and
moves it to kernel/sched/completion.c so that other kernel subsystems can
use it. It will be needed by the dm-io subsystem.

Signed-off-by: Mikulas Patocka <mpatocka@...hat.com>

---
 block/bio.c                |    2 +-
 block/blk-mq.c             |    2 +-
 block/blk.h                |   12 ------------
 include/linux/completion.h |    1 +
 kernel/sched/completion.c  |   20 ++++++++++++++++++++
 5 files changed, 23 insertions(+), 14 deletions(-)

Index: linux-2.6/block/blk.h
===================================================================
--- linux-2.6.orig/block/blk.h	2024-04-17 19:41:14.000000000 +0200
+++ linux-2.6/block/blk.h	2024-04-17 19:41:14.000000000 +0200
@@ -72,18 +72,6 @@ static inline int bio_queue_enter(struct
 	return __bio_queue_enter(q, bio);
 }
 
-static inline void blk_wait_io(struct completion *done)
-{
-	/* Prevent hang_check timer from firing at us during very long I/O */
-	unsigned long timeout = sysctl_hung_task_timeout_secs * HZ / 2;
-
-	if (timeout)
-		while (!wait_for_completion_io_timeout(done, timeout))
-			;
-	else
-		wait_for_completion_io(done);
-}
-
 #define BIO_INLINE_VECS 4
 struct bio_vec *bvec_alloc(mempool_t *pool, unsigned short *nr_vecs,
 		gfp_t gfp_mask);
Index: linux-2.6/include/linux/completion.h
===================================================================
--- linux-2.6.orig/include/linux/completion.h	2024-04-17 19:41:14.000000000 +0200
+++ linux-2.6/include/linux/completion.h	2024-04-17 19:41:14.000000000 +0200
@@ -112,6 +112,7 @@ extern long wait_for_completion_interrup
 	struct completion *x, unsigned long timeout);
 extern long wait_for_completion_killable_timeout(
 	struct completion *x, unsigned long timeout);
+extern void wait_for_completion_long_io(struct completion *x);
 extern bool try_wait_for_completion(struct completion *x);
 extern bool completion_done(struct completion *x);
 
Index: linux-2.6/block/bio.c
===================================================================
--- linux-2.6.orig/block/bio.c	2024-04-17 19:41:14.000000000 +0200
+++ linux-2.6/block/bio.c	2024-04-17 19:41:14.000000000 +0200
@@ -1378,7 +1378,7 @@ int submit_bio_wait(struct bio *bio)
 	bio->bi_end_io = submit_bio_wait_endio;
 	bio->bi_opf |= REQ_SYNC;
 	submit_bio(bio);
-	blk_wait_io(&done);
+	wait_for_completion_long_io(&done);
 
 	return blk_status_to_errno(bio->bi_status);
 }
Index: linux-2.6/block/blk-mq.c
===================================================================
--- linux-2.6.orig/block/blk-mq.c	2024-04-17 19:41:14.000000000 +0200
+++ linux-2.6/block/blk-mq.c	2024-04-17 19:41:14.000000000 +0200
@@ -1407,7 +1407,7 @@ blk_status_t blk_execute_rq(struct reque
 	if (blk_rq_is_poll(rq))
 		blk_rq_poll_completion(rq, &wait.done);
 	else
-		blk_wait_io(&wait.done);
+		wait_for_completion_long_io(&wait.done);
 
 	return wait.ret;
 }
Index: linux-2.6/kernel/sched/completion.c
===================================================================
--- linux-2.6.orig/kernel/sched/completion.c	2024-04-17 19:41:14.000000000 +0200
+++ linux-2.6/kernel/sched/completion.c	2024-04-17 19:41:14.000000000 +0200
@@ -290,6 +290,26 @@ wait_for_completion_killable_timeout(str
 EXPORT_SYMBOL(wait_for_completion_killable_timeout);
 
 /**
+ * wait_for_completion_long_io - waits for completion of a task
+ * @x:  holds the state of this particular completion
+ *
+ * This is like wait_for_completion_io, but it doesn't warn if the wait takes
+ * too long.
+ */
+void wait_for_completion_long_io(struct completion *x)
+{
+	/* Prevent hang_check timer from firing at us during very long I/O */
+	unsigned long timeout = sysctl_hung_task_timeout_secs * HZ / 2;
+
+	if (timeout)
+		while (!wait_for_completion_io_timeout(x, timeout))
+			;
+	else
+		wait_for_completion_io(x);
+}
+EXPORT_SYMBOL(wait_for_completion_long_io);
+
+/**
  *	try_wait_for_completion - try to decrement a completion without blocking
  *	@x:	completion structure
  *