Re: [PATCH v2 6/6] btrfs: implement remove_bdev super operation callback

[Anand Jain <anand.jain@oracle.com>]

> +#ifdef CONFIG_BTRFS_EXPERIMENTAL
> +static void btrfs_remove_bdev(struct super_block *sb, struct block_device *bdev)
> +{
> +	struct btrfs_fs_info *fs_info = btrfs_sb(sb);
> +	struct btrfs_device *device;
> +	struct btrfs_dev_lookup_args lookup_args = { .devt = bdev->bd_dev };
> +	bool can_rw;
> +
> +	mutex_lock(&fs_info->fs_devices->device_list_mutex);
> +	device = btrfs_find_device(fs_info->fs_devices, &lookup_args);
> +	if (!device) {
> +		btrfs_warn(fs_info, "unable to find btrfs device for block device '%pg'",
> +			   bdev);
> +		mutex_unlock(&fs_info->fs_devices->device_list_mutex);
> +		return;
> +	}
> +	set_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state);
> +	device->fs_devices->missing_devices++;

Where do we ensure that the block device wasn't already marked as
missing? If there's no such check, could missing_devices end up
exceeding total_devices?

Thanks, Anand