linux-kernel - [PATCH v2 1/2] md: factor out a new helper to put mddev

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Date:   Tue, 26 Sep 2023 10:58:26 +0800
From:   Yu Kuai <yukuai1@...weicloud.com>
To:     mariusz.tkaczyk@...ux.intel.com, xni@...hat.com, song@...nel.org
Cc:     linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org,
        yukuai3@...wei.com, yukuai1@...weicloud.com, yi.zhang@...wei.com,
        yangerkun@...wei.com
Subject: [PATCH v2 1/2] md: factor out a new helper to put mddev

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

There are no functional changes, the new helper will still hold
'all_mddevs_lock' after putting mddev, and it will be used to simplify
md_seq_ops.

Signed-off-by: Yu Kuai <yukuai3@...wei.com>
---
 drivers/md/md.c | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 10cb4dfbf4ae..a5ef6f7da8ec 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -616,10 +616,15 @@ static inline struct mddev *mddev_get(struct mddev *mddev)
 
 static void mddev_delayed_delete(struct work_struct *ws);
 
-void mddev_put(struct mddev *mddev)
+static void __mddev_put(struct mddev *mddev, bool locked)
 {
-	if (!atomic_dec_and_lock(&mddev->active, &all_mddevs_lock))
+	if (locked) {
+		spin_lock(&all_mddevs_lock);
+		if (!atomic_dec_and_test(&mddev->active))
+			return;
+	} else if (!atomic_dec_and_lock(&mddev->active, &all_mddevs_lock))
 		return;
+
 	if (!mddev->raid_disks && list_empty(&mddev->disks) &&
 	    mddev->ctime == 0 && !mddev->hold_active) {
 		/* Array is not configured at all, and not held active,
@@ -633,7 +638,14 @@ void mddev_put(struct mddev *mddev)
 		 */
 		queue_work(md_misc_wq, &mddev->del_work);
 	}
-	spin_unlock(&all_mddevs_lock);
+
+	if (!locked)
+		spin_unlock(&all_mddevs_lock);
+}
+
+void mddev_put(struct mddev *mddev)
+{
+	__mddev_put(mddev, false);
 }
 
 static void md_safemode_timeout(struct timer_list *t);
-- 
2.39.2