Commit 5ce10a38 authored by Yu Kuai's avatar Yu Kuai Committed by Song Liu
Browse files

md: don't fail action_store() if sync_thread is not registered 



MD_RECOVERY_RUNNING will always be set when trying to register a new
sync_thread, however, if md_start_sync() turns out to do nothing,
MD_RECOVERY_RUNNING will be cleared in this case. And during the race
window, action_store() will return -EBUSY, which will cause some
mdadm tests to fail. For example:

The test 07reshape5intr will add a new disk to array, then start
reshape:

mdadm /dev/md0 --add /dev/xxx
mdadm --grow /dev/md0 -n 3

And add_bound_rdev() from mdadm --add will set MD_RECOVERY_NEEDED,
then during the race windown, mdadm --grow will fail.

Fix the problem by waiting in action_store() during the race window,
fail only if sync_thread is registered.

Signed-off-by: default avatarYu Kuai <yukuai3@huawei.com>
Signed-off-by: default avatarSong Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20240611132251.1967786-8-yukuai1@huaweicloud.com
parent df79234b

drivers/md/md.c

+33 −52
Original line number Diff line number Diff line
@@ -753,7 +753,6 @@ int mddev_init(struct mddev *mddev) 


	mutex_init(&mddev->open_mutex);

	mutex_init(&mddev->reconfig_mutex);

	mutex_init(&mddev->sync_mutex);

	mutex_init(&mddev->suspend_mutex);

	mutex_init(&mddev->bitmap_info.mutex);

	INIT_LIST_HEAD(&mddev->disks);
@@ -5021,34 +5020,6 @@ void md_unfrozen_sync_thread(struct mddev *mddev) 
}

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;

	}



	stop_sync_thread(mddev, false);

	mutex_unlock(&mddev->sync_mutex);

}



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;

	}



	stop_sync_thread(mddev, false);

	mutex_unlock(&mddev->sync_mutex);

}



static int mddev_start_reshape(struct mddev *mddev)

{

	int ret;
@@ -5056,24 +5027,13 @@ static int mddev_start_reshape(struct mddev *mddev) 
	if (mddev->pers->start_reshape == NULL)

		return -EINVAL;



	ret = mddev_lock(mddev);

	if (ret)

		return ret;



	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) {

		mddev_unlock(mddev);

		return -EBUSY;

	}



	if (mddev->reshape_position == MaxSector ||

	    mddev->pers->check_reshape == NULL ||

	    mddev->pers->check_reshape(mddev)) {

		clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);

		ret = mddev->pers->start_reshape(mddev);

		if (ret) {

			mddev_unlock(mddev);

		if (ret)

			return ret;

		}

	} else {

		/*

		 * If reshape is still in progress, and md_check_recovery() can
@@ -5083,7 +5043,6 @@ static int mddev_start_reshape(struct mddev *mddev) 
		clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);

	}



	mddev_unlock(mddev);

	sysfs_notify_dirent_safe(mddev->sysfs_degraded);

	return 0;

}
@@ -5097,36 +5056,53 @@ action_store(struct mddev *mddev, const char *page, size_t len) 
	if (!mddev->pers || !mddev->pers->sync_request)

		return -EINVAL;



retry:

	if (work_busy(&mddev->sync_work))

		flush_work(&mddev->sync_work);



	ret = mddev_lock(mddev);

	if (ret)

		return ret;



	if (work_busy(&mddev->sync_work)) {

		mddev_unlock(mddev);

		goto retry;

	}



	action = md_sync_action_by_name(page);



	/* TODO: mdadm rely on "idle" to start sync_thread. */

	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) {

		switch (action) {

		case ACTION_FROZEN:

			frozen_sync_thread(mddev);

			return len;

			md_frozen_sync_thread(mddev);

			ret = len;

			goto out;

		case ACTION_IDLE:

			idle_sync_thread(mddev);

			md_idle_sync_thread(mddev);

			break;

		case ACTION_RESHAPE:

		case ACTION_RECOVER:

		case ACTION_CHECK:

		case ACTION_REPAIR:

		case ACTION_RESYNC:

			return -EBUSY;

			ret = -EBUSY;

			goto out;

		default:

			return -EINVAL;

			ret = -EINVAL;

			goto out;

		}

	} else {

		switch (action) {

		case ACTION_FROZEN:

			set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);

			return len;

			ret = len;

			goto out;

		case ACTION_RESHAPE:

			clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);

			ret = mddev_start_reshape(mddev);

			if (ret)

				return ret;

				goto out;

			break;

		case ACTION_RECOVER:

			clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
@@ -5144,7 +5120,8 @@ action_store(struct mddev *mddev, const char *page, size_t len) 
			clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);

			break;

		default:

			return -EINVAL;

			ret = -EINVAL;

			goto out;

		}

	}
@@ -5152,14 +5129,18 @@ action_store(struct mddev *mddev, const char *page, size_t len) 
		/* A write to sync_action is enough to justify

		 * canceling read-auto mode

		 */

		flush_work(&mddev->sync_work);

		mddev->ro = MD_RDWR;

		md_wakeup_thread(mddev->sync_thread);

	}



	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);

	md_wakeup_thread(mddev->thread);

	sysfs_notify_dirent_safe(mddev->sysfs_action);

	return len;

	ret = len;



out:

	mddev_unlock(mddev);

	return ret;

}



static struct md_sysfs_entry md_scan_mode =

drivers/md/md.h

+0 −2
Original line number Diff line number Diff line
@@ -595,8 +595,6 @@ struct mddev { 
	 */

	struct list_head		deleting;



	/* Used to synchronize idle and frozen for action_store() */

	struct mutex			sync_mutex;

	/* The sequence number for sync thread */

	atomic_t sync_seq;