[PATCH 00/12, DEV-ONLY] xfsprogs: metadata CRC support, first batch

[Mark Tinguely]

On 01/21/13 23:51, Dave Chinner wrote:
> On Tue, Jan 22, 2013 at 12:52:59AM +1100, Dave Chinner wrote:
>> Hi folks,
>>
...

> Just a word of note about xfs_db. xfs_db does not use libxfs for
> reading and writing stuff from disk, so currently has no
> infrastructure for checking or calculating checksums. Hence anything
> that you do with xfs_db to write to disk on a CRC enabled filesystem
> will corrupt it as it will invalidate the on-disk CRC.
>
> Hence there are various xfstests that use xfs_db to write different
> values into structures (e.g. 045, which writes a UUID into the
> superblock) will not work. Indeed, this specific operation needs to
> be disallowed on version 5 superblocks - the UUID is stamped into
> every single piece of metadata, so changing it is, well, a whol elot
> more complex that reading and writing the superblocks....
>
> As a result, right now my only focus for xfs_db is for it to be able
> to parse the structures correctly. We'll have to decide what the
> best approach to fixing these problems in xfs-db are - rewriting it
> to use libxfs is a major undertaking, but then again so is
> architecting in the verifiers for CRC checking and calculation. And
> I don't really like the idea of have two different implementations
> of the same thing in the one place at the best of times....
>
> Cheers,
>
> Dave.
>

Thanks for the heads-up.

--Mark.