Re: [PATCH] bcache: Take data offset from the bdev superblock.

[Gabriel de Perthuis <g2p.code-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

>> As for BCACHE_SB_VERSION_CDEV_WITH_UUID, can you explain why you added
>> that? I suspect it's needed but I can't remember why I didn't add it
>> when I added the new UUID format (or perhaps I just forgot)
>
> I took the name from a comment in the kernel-side bcache.h.
> BCACHE_SB_VERSION_CDEV is the version make-bcache writes, and
> BCACHE_SB_VERSION_CDEV_WITH_UUID is what the kernel updates it too; I
> just changed the version names so that user-side and kernel-side were
> more consistent, internally and with each other.
> The kernel doesn't discriminate these two versions when opening, so it
> should be possible to define only the latter and deprecate the other.

To be more clear, I've replaced the kernel's BCACHE_SB_VERSION by 
BCACHE_SB_VERSION_CDEV_WITH_UUID or BCACHE_SB_MAX_VERSION depending on 
the intent.