On Monday, 12 December, 2011 15:41:29 you wrote:
> >You can't change the uuid of an existing btrfs partition. Well, you
> >can, but you have to rewrite all the metadata blocks.
>
> Is there a tool that would allow me to rewrite all the metadata blocks with
> a new UUID? At this point, it can't possibly take longer than the way I'm
> trying to do it now...
>
> Someone once said "Resetting the UUID on btrfs isn't a quick-and-easy thing
> - you have to walk the entire tree and change every object. We've got a
> bad-hack in meego that uses btrfs-debug-tree and changes the UUID while it
> runs the entire tree, but it's ugly as hell."
I am looking for that. btrfs-debug-tree is capable to dump every leaf and
every node logical address.
To change the UUID of a btrfs filesystem
On every leaf/node we should
- update the FSID (a)
- update the chunk_uuid [*]
- update the checksum
for the "dev_item" items we should update the
- device UUID (b)
- FSID (see
'a')
for the "chunk_item" items we should update the
- device UUID of every stripe (b)
for every superblock (three for device), we should update:
- FSID (see
'a')
- device uuid (see 'b')
- for every "system chunk" items contained in the superblock we should update:
- device UUID of every stripe (b)
- update the checksum
The most complex part is to map the logical address to the physical device.
In the next days I will tray (if I had enough time) to make something...
>
> Ok, I'll take the bad-hack. How would I actually go about using said
> bad-hack?
>
> -BJ
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