btrfs: move commit out of sysfs when changing label

Signed-off-by: NDavid Sterba <dsterba@suse.cz>

fs/btrfs/sysfs.c

@@ -369,9 +369,6 @@ static ssize_t btrfs_label_store(struct kobject *kobj,
 				 const char *buf, size_t len)
 {
 	struct btrfs_fs_info *fs_info = to_fs_info(kobj);
-	struct btrfs_trans_handle *trans;
-	struct btrfs_root *root = fs_info->fs_root;
-	int ret;
 	size_t p_len;
 
 	if (fs_info->sb->s_flags & MS_RDONLY)
@@ -386,20 +383,18 @@ static ssize_t btrfs_label_store(struct kobject *kobj,
 	if (p_len >= BTRFS_LABEL_SIZE)
 		return -EINVAL;
 
-	trans = btrfs_start_transaction(root, 0);
-	if (IS_ERR(trans))
-		return PTR_ERR(trans);
-
-	spin_lock(&root->fs_info->super_lock);
+	spin_lock(&fs_info->super_lock);
 	memset(fs_info->super_copy->label, 0, BTRFS_LABEL_SIZE);
 	memcpy(fs_info->super_copy->label, buf, p_len);
-	spin_unlock(&root->fs_info->super_lock);
-	ret = btrfs_commit_transaction(trans, root);
+	spin_unlock(&fs_info->super_lock);
 
-	if (!ret)
-		return len;
+	/*
+	 * We don't want to do full transaction commit from inside sysfs
+	 */
+	btrfs_set_pending(fs_info, COMMIT);
+	wake_up_process(fs_info->transaction_kthread);
 
-	return ret;
+	return len;
 }
 BTRFS_ATTR_RW(label, btrfs_label_show, btrfs_label_store);