linux-kernel - [PATCH] aio: use wait_for_completion_io() when waiting for completion of io

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Message-Id: <1596634551-27526-1-git-send-email-xianting_tian@126.com>
Date:   Wed,  5 Aug 2020 09:35:51 -0400
From:   Xianting Tian <xianting_tian@....com>
To:     bcrl@...ck.org, viro@...iv.linux.org.uk
Cc:     linux-aio@...ck.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] aio: use wait_for_completion_io() when waiting for completion of io

When waiting for the completion of io, we need account iowait time. As
wait_for_completion() calls schedule_timeout(), which doesn't account
iowait time. While wait_for_completion_io() calls io_schedule_timeout(),
which will account iowait time.

So using wait_for_completion_io() instead of wait_for_completion()
when waiting for completion of io before exit_aio and io_destroy.

Signed-off-by: Xianting Tian <xianting_tian@....com>
---
 fs/aio.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/aio.c b/fs/aio.c
index 91e7cc4..498b8a0 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -892,7 +892,7 @@ void exit_aio(struct mm_struct *mm)
 
 	if (!atomic_sub_and_test(skipped, &wait.count)) {
 		/* Wait until all IO for the context are done. */
-		wait_for_completion(&wait.comp);
+		wait_for_completion_io(&wait.comp);
 	}
 
 	RCU_INIT_POINTER(mm->ioctx_table, NULL);
@@ -1400,7 +1400,7 @@ static long read_events(struct kioctx *ctx, long min_nr, long nr,
 		 * is destroyed.
 		 */
 		if (!ret)
-			wait_for_completion(&wait.comp);
+			wait_for_completion_io(&wait.comp);
 
 		return ret;
 	}
-- 
1.8.3.1