Re: reiserfs NET=n build error

[Jeff Mahoney <jeffm@suse.com>]

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Al Viro wrote:
> On Sun, Nov 19, 2006 at 11:04:33AM -0800, Randy Dunlap wrote:
>> Andi Kleen wrote:
>>>>> I would copy a relatively simple C implementation, like 
>>>>> arch/h8300/lib/checksum.c
>>>> As long as the h8300 version has the same output as the x86 version.
>>> The trouble is that the different architecture have different output 
>>> for csum_partial. So you already got a bug when someone wants to move
>>> file systems.
>>>
>>> -Andi
>> That argues for having only one version of it (in a lib.; my preference)
>> -or- Every module having its own local copy/version of it.  :(
> 
> Wrong.  csum_partial() result is defined modulo 0xffff and it's basically
> "whatever's convenient as intermediate for this architecture".
> 
> reiserfs use of it is just plain broken.  net/* is fine, since all
> final uses are via csum_fold() or equivalents.
> 
> Note that reiserfs use is broken in another way: it takes fixed-endian value
> and feeds it to cpu_to_le32().  IOW, even if everything had literally the
> same csum_partial(), the value it shits on disk would be endian-dependent.

Oh great. Even better. :(

- -Jeff

- --
Jeff Mahoney
SUSE Labs
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