Merge tag 'md-6.12-20240906' of https://git.kernel.org/pub/scm/linux/kernel/git/song/md into for-6.12/block

Pull MD updates from Song:

"This patch, by Xiao Ni, adds a sysfs entry 'new_level'."

* tag 'md-6.12-20240906' of https://git.kernel.org/pub/scm/linux/kernel/git/song/md:
  md: Add new_level sysfs interface

Author: axboe

drivers/md/md.c

@@ -4052,6 +4052,34 @@ level_store(struct mddev *mddev, const char *buf, size_t len)
 static struct md_sysfs_entry md_level =
 __ATTR(level, S_IRUGO|S_IWUSR, level_show, level_store);
 
+static ssize_t
+new_level_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%d\n", mddev->new_level);
+}
+
+static ssize_t
+new_level_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	unsigned int n;
+	int err;
+
+	err = kstrtouint(buf, 10, &n);
+	if (err < 0)
+		return err;
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+
+	mddev->new_level = n;
+	md_update_sb(mddev, 1);
+
+	mddev_unlock(mddev);
+	return len;
+}
+static struct md_sysfs_entry md_new_level =
+__ATTR(new_level, 0664, new_level_show, new_level_store);
+
 static ssize_t
 layout_show(struct mddev *mddev, char *page)
 {
@@ -5583,6 +5611,7 @@ __ATTR(serialize_policy, S_IRUGO | S_IWUSR, serialize_policy_show,
 
 static struct attribute *md_default_attrs[] = {
 	&md_level.attr,
+	&md_new_level.attr,
 	&md_layout.attr,
 	&md_raid_disks.attr,
 	&md_uuid.attr,