[PATCH v4 05/14] md: export helpers to stop sync_thread

[Yu Kuai <yukuai1@xxxxxxxxxxxxxxx>]

From: Yu Kuai <yukuai3@xxxxxxxxxx>

The new heleprs will be used in dm-raid in later patches to fix
regressions and prevent calling md_reap_sync_thread() directly.

Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
 drivers/md/md.c | 33 +++++++++++++++++++++++++++++++--
 drivers/md/md.h |  3 +++
 2 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 6c5d0a372927..6a76bd27e381 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -4915,16 +4915,45 @@ static void stop_sync_thread(struct mddev *mddev, bool locked, bool check_seq)
 		mddev_lock_nointr(mddev);
 }
 
+void md_idle_sync_thread(struct mddev *mddev)
+{
+	lockdep_assert_held(&mddev->reconfig_mutex);
+
+	clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+	stop_sync_thread(mddev, true, true);
+}
+EXPORT_SYMBOL_GPL(md_idle_sync_thread);
+
+void md_frozen_sync_thread(struct mddev *mddev)
+{
+	lockdep_assert_held(&mddev->reconfig_mutex);
+
+	set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+	stop_sync_thread(mddev, true, false);
+}
+EXPORT_SYMBOL_GPL(md_frozen_sync_thread);
+
+void md_unfrozen_sync_thread(struct mddev *mddev)
+{
+	lockdep_assert_held(&mddev->reconfig_mutex);
+
+	clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+	md_wakeup_thread(mddev->thread);
+	sysfs_notify_dirent_safe(mddev->sysfs_action);
+}
+EXPORT_SYMBOL_GPL(md_unfrozen_sync_thread);
+
 static void idle_sync_thread(struct mddev *mddev)
 {
 	mutex_lock(&mddev->sync_mutex);
-	clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
 
 	if (mddev_lock(mddev)) {
 		mutex_unlock(&mddev->sync_mutex);
 		return;
 	}
 
+	clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
 	stop_sync_thread(mddev, false, true);
 	mutex_unlock(&mddev->sync_mutex);
 }
@@ -4932,13 +4961,13 @@ static void idle_sync_thread(struct mddev *mddev)
 static void frozen_sync_thread(struct mddev *mddev)
 {
 	mutex_lock(&mddev->sync_mutex);
-	set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
 
 	if (mddev_lock(mddev)) {
 		mutex_unlock(&mddev->sync_mutex);
 		return;
 	}
 
+	set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
 	stop_sync_thread(mddev, false, false);
 	mutex_unlock(&mddev->sync_mutex);
 }
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 8d881cc59799..437ab70ce79b 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -781,6 +781,9 @@ extern void md_rdev_clear(struct md_rdev *rdev);
 extern void md_handle_request(struct mddev *mddev, struct bio *bio);
 extern int mddev_suspend(struct mddev *mddev, bool interruptible);
 extern void mddev_resume(struct mddev *mddev);
+extern void md_idle_sync_thread(struct mddev *mddev);
+extern void md_frozen_sync_thread(struct mddev *mddev);
+extern void md_unfrozen_sync_thread(struct mddev *mddev);
 
 extern void md_reload_sb(struct mddev *mddev, int raid_disk);
 extern void md_update_sb(struct mddev *mddev, int force);
-- 
2.39.2