Re: [PATCH] btrfs-progs: btrfstune: Register new UUIDs after uuid change

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

On 10/10/16 17:21, Qu Wenruo wrote:
> For multi-device btrfs, after UUID change we should info kernel, or new
> fs can't be mounted due to false alert on missing devices.
>
> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
> ---
>  btrfstune.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/btrfstune.c b/btrfstune.c
> index 15dde90..23d06ce 100644
> --- a/btrfstune.c
> +++ b/btrfstune.c
> @@ -369,6 +369,15 @@ static int change_uuid(struct btrfs_fs_info *fs_info, const char *new_fsid_str)
>  	fs_info->new_fsid = NULL;
>  	fs_info->new_chunk_tree_uuid = NULL;
>  	printf("Fsid change finished\n");
> +
> +	/*
> +	 * Register new devices, or multi-volume btrfs can't be mounted until
> +	 * device scan happens.
> +	 * Ignore any error, as such register is optional.
> +	 */
> +	printf("Register new UUIDs(error can be ignored)\n");

  Whats the error in particular in this context. ?

> +	btrfs_register_all_devices();

  That means after a reboot -> change uuid it will register the devices 
though the devices weren't registered to the kernel before.

  Its fair enough just remind user to run dev scan so that kernel can 
see them.

Thanks, Anand


> +
>  out:
>  	return ret;
>  }
>