linux-kernel - [PATCH v2 09/11] md: add atomic mode switching when removing disk

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Date: Thu, 18 Apr 2024 05:44:23 +0000
From: tada keisuke <keisuke1.tada@...xia.com>
To: "song@...nel.org" <song@...nel.org>,
        "yukuai3@...wei.com"
	<yukuai3@...wei.com>
CC: "linux-raid@...r.kernel.org" <linux-raid@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [PATCH v2 09/11] md: add atomic mode switching when removing disk

This patch depends on patch 08.

To minimize the number of execution of atomic mode switching, not only adding atomic mode switching, but also remove judgment is divided into two stages.
Latency is minimized because only rdev to be removed is switched to atomic mode, not all rdevs.

Signed-off-by: Keisuke TADA <keisuke1.tada@...xia.com>
Signed-off-by: Toshifumi OHTAKE <toshifumi.ootake@...xia.com>
---
 drivers/md/md.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 7e6966e65d0d..5f785353353d 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -9291,8 +9291,11 @@ static bool rdev_removeable(struct md_rdev *rdev)
 		return false;
 
 	/* Fautly rdev is not used, it's safe to remove it. */
-	if (test_bit(Faulty, &rdev->flags))
-		return true;
+	if (nr_pending_is_percpu_mode(rdev) && test_bit(Faulty, &rdev->flags)) {
+		percpu_ref_switch_to_atomic_sync(&rdev->nr_pending);
+		if (nr_pending_is_zero(rdev))
+			return true;
+	}
 
 	/* Journal disk can only be removed if it's faulty. */
 	if (test_bit(Journal, &rdev->flags))
@@ -9346,6 +9349,11 @@ static bool md_spares_need_change(struct mddev *mddev)
 {
 	struct md_rdev *rdev;
 
+	rdev_for_each_rcu(rdev, mddev) {
+		if (test_bit(Faulty, &rdev->flags))
+			percpu_ref_switch_to_atomic_sync(&rdev->nr_pending);
+	}
+
 	rcu_read_lock();
 	rdev_for_each_rcu(rdev, mddev) {
 		if (rdev_removeable(rdev) || rdev_addable(rdev)) {
-- 
2.34.1