linux-kernel - [PATCH v3 1/5] md/raid10: factor out code from wait_barrier() to stop_waiting

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Date:   Fri, 16 Sep 2022 19:34:24 +0800
From:   Yu Kuai <yukuai1@...weicloud.com>
To:     song@...nel.org, logang@...tatee.com, guoqing.jiang@...ux.dev,
        pmenzel@...gen.mpg.de
Cc:     linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org,
        yukuai3@...wei.com, yukuai1@...weicloud.com, yi.zhang@...wei.com
Subject: [PATCH v3 1/5] md/raid10: factor out code from wait_barrier() to stop_waiting_barrier()

From: Yu Kuai <yukuai3@...wei.com>

Currently the nasty condition in wait_barrier() is hard to read. This
patch factors out the condition into a function.

There are no functional changes.

Signed-off-by: Yu Kuai <yukuai3@...wei.com>
Acked-by: Paul Menzel <pmenzel@...gen.mpg.de>
---
 drivers/md/raid10.c | 50 +++++++++++++++++++++++++--------------------
 1 file changed, 28 insertions(+), 22 deletions(-)

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 64d6e4cd8a3a..37fd9284054e 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -957,41 +957,47 @@ static void lower_barrier(struct r10conf *conf)
 	wake_up(&conf->wait_barrier);
 }
 
+static bool stop_waiting_barrier(struct r10conf *conf)
+{
+	struct bio_list *bio_list = current->bio_list;
+
+	/* barrier is dropped */
+	if (!conf->barrier)
+		return true;
+
+	/*
+	 * If there are already pending requests (preventing the barrier from
+	 * rising completely), and the pre-process bio queue isn't empty, then
+	 * don't wait, as we need to empty that queue to get the nr_pending
+	 * count down.
+	 */
+	if (atomic_read(&conf->nr_pending) && bio_list &&
+	    (!bio_list_empty(&bio_list[0]) || !bio_list_empty(&bio_list[1])))
+		return true;
+
+	/* move on if recovery thread is blocked by us */
+	if (conf->mddev->thread->tsk == current &&
+	    test_bit(MD_RECOVERY_RUNNING, &conf->mddev->recovery) &&
+	    conf->nr_queued > 0)
+		return true;
+
+	return false;
+}
+
 static bool wait_barrier(struct r10conf *conf, bool nowait)
 {
 	bool ret = true;
 
 	spin_lock_irq(&conf->resync_lock);
 	if (conf->barrier) {
-		struct bio_list *bio_list = current->bio_list;
 		conf->nr_waiting++;
-		/* Wait for the barrier to drop.
-		 * However if there are already pending
-		 * requests (preventing the barrier from
-		 * rising completely), and the
-		 * pre-process bio queue isn't empty,
-		 * then don't wait, as we need to empty
-		 * that queue to get the nr_pending
-		 * count down.
-		 */
 		/* Return false when nowait flag is set */
 		if (nowait) {
 			ret = false;
 		} else {
 			raid10_log(conf->mddev, "wait barrier");
 			wait_event_lock_irq(conf->wait_barrier,
-					    !conf->barrier ||
-					    (atomic_read(&conf->nr_pending) &&
-					     bio_list &&
-					     (!bio_list_empty(&bio_list[0]) ||
-					      !bio_list_empty(&bio_list[1]))) ||
-					     /* move on if recovery thread is
-					      * blocked by us
-					      */
-					     (conf->mddev->thread->tsk == current &&
-					      test_bit(MD_RECOVERY_RUNNING,
-						       &conf->mddev->recovery) &&
-					      conf->nr_queued > 0),
+					    stop_waiting_barrier(conf),
 					    conf->resync_lock);
 		}
 		conf->nr_waiting--;
-- 
2.31.1