btrfs-progs 4.1-rc1: btrfstune -u reporting incorrect current fsid?

btrfs-progs 4.1-rc1: btrfstune -u reporting incorrect current fsid?

[Mike Fleetwood]

Hi,

I've done a quick test on changing the UUID of a btrfs.  It worked, but
btrfstune -u didn't print the same current uuid that btrfs fi sh does.
It also upper cases the UUID where as btrfs fi sh and blkid don't.

Thanks,
Mike

# btrfs filesystem show /dev/sdb1 | fgrep uuid
Label: none  uuid: b2813976-4d8b-4976-9d59-cbfbd588399c

# ~fedora/programming/c/btrfs-progs-unstable/btrfstune -f -u /dev/sdb1
Current fsid: FFFFFFFF-0000-0000-00B0-8F12937F0000
New fsid: D294F3F3-F2B7-4407-B83A-DE5A4F8CBAB1
Set superblock flag CHANGING_FSID
Change fsid in extents
Change fsid on devices
Clear superblock flag CHANGING_FSID
Fsid change finished

# btrfs filesystem show /dev/sdb1 | fgrep uuid
Label: none  uuid: d294f3f3-f2b7-4407-b83a-de5a4f8cbab1

# blkid | fgrep sdb1
/dev/sdb1: UUID="d294f3f3-f2b7-4407-b83a-de5a4f8cbab1"
UUID_SUB="70065403-5ec1-462c-93a4-26cff8b6aea2" TYPE="btrfs"
PARTUUID="b309c48c-486f-4882-896c-34d4d0aeb529"

Re: btrfs-progs 4.1-rc1: btrfstune -u reporting incorrect current fsid?

[David Sterba]

On Wed, Jun 17, 2015 at 10:21:45PM +0100, Mike Fleetwood wrote:
> It also upper cases the UUID where as btrfs fi sh and blkid don't.

Ok, I'll switch that to lowercase so it's consistent with the rest.

> I've done a quick test on changing the UUID of a btrfs.  It worked, but
> btrfstune -u didn't print the same current uuid that btrfs fi sh does.

Seems that the reporting is broken in the btrfstune side. I've
reproduced it here. I've used btrfs-show-super in the tests and did not
notice that the 'current fsid' is wrong. Thanks.

Re: btrfs-progs 4.1-rc1: btrfstune -u reporting incorrect current fsid?

[Qu Wenruo]

David Sterba wrote on 2015/06/18 19:33 +0200:
> On Wed, Jun 17, 2015 at 10:21:45PM +0100, Mike Fleetwood wrote:
>> It also upper cases the UUID where as btrfs fi sh and blkid don't.
>
> Ok, I'll switch that to lowercase so it's consistent with the rest.
>
>> I've done a quick test on changing the UUID of a btrfs.  It worked, but
>> btrfstune -u didn't print the same current uuid that btrfs fi sh does.
>
> Seems that the reporting is broken in the btrfstune side. I've
> reproduced it here. I've used btrfs-show-super in the tests and did not
> notice that the 'current fsid' is wrong. Thanks.

Just a little tip to take less time on the bug:
---
--- a/btrfstune.c
+++ b/btrfstune.c
@@ -349,7 +349,7 @@ static int change_uuid(struct btrfs_fs_info 
*fs_info, const char *new_fsid_str)
         fs_info->new_fsid = new_fsid;
         fs_info->new_chunk_tree_uuid = new_chunk_id;

-       uuid_parse((const char*)fs_info->fsid, old_fsid);
+       memcpy(old_fsid, fs_info->fsid, BTRFS_UUID_SIZE);
         uuid_unparse_upper(old_fsid, uuid_buf);
         printf("Current fsid: %s\n", uuid_buf);

---

Also, you can remove the old_fsid variant if you want and just use 
fs_info->fsid.

Thanks,
Qu

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Re: btrfs-progs 4.1-rc1: btrfstune -u reporting incorrect current fsid?

[David Sterba]

On Fri, Jun 19, 2015 at 09:40:37AM +0800, Qu Wenruo wrote:
> Just a little tip to take less time on the bug:
> -       uuid_parse((const char*)fs_info->fsid, old_fsid);
> +       memcpy(old_fsid, fs_info->fsid, BTRFS_UUID_SIZE);

Thanks, that's what I did.