md: add new helpers to suspend/resume and lock/unlock array

The new helpers suspend the array first and then lock the array,

Prepare to refactor from:

mddev_lock/lock_nointr
mddev_suspend
...
mddev_resuem
mddev_lock

With:

mddev_suspend_and_lock/lock_nointr
...
mddev_unlock_and_resume

After all the use cases is refactored, mddev_suspend/resume() will be
removed.

And mddev_suspend_and_lock() will also replace mddev_lock() for the case
that the array will be reconfigured, in order to synchronize with io to
prevent problems in many corner cases.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20231010151958.145896-6-yukuai1@huaweicloud.com

drivers/md/md.h

@@ -858,6 +858,33 @@ static inline void mddev_check_write_zeroes(struct mddev *mddev, struct bio *bio
 		mddev->queue->limits.max_write_zeroes_sectors = 0;
 }
 
+static inline int mddev_suspend_and_lock(struct mddev *mddev)
+{
+	int ret;
+
+	ret = __mddev_suspend(mddev, true);
+	if (ret)
+		return ret;
+
+	ret = mddev_lock(mddev);
+	if (ret)
+		__mddev_resume(mddev);
+
+	return ret;
+}
+
+static inline void mddev_suspend_and_lock_nointr(struct mddev *mddev)
+{
+	__mddev_suspend(mddev, false);
+	mutex_lock(&mddev->reconfig_mutex);
+}
+
+static inline void mddev_unlock_and_resume(struct mddev *mddev)
+{
+	mddev_unlock(mddev);
+	__mddev_resume(mddev);
+}
+
 struct mdu_array_info_s;
 struct mdu_disk_info_s;