[Linux-cluster] Re: [PATCH 00/14] GFS

[Arjan van de Ven <arjan infradead org>]

On Fri, 2005-08-05 at 15:14 +0800, David Teigland wrote:
> On Tue, Aug 02, 2005 at 09:45:24AM +0200, Arjan van de Ven wrote:
> 
> > * +static const uint32_t crc_32_tab[] = .....
> > why do you duplicate this? The kernel has a perfectly good set of
> > generic crc32 tables/functions just fine
> 
> The gfs2_disk_hash() function and the crc table on which it's based are a
> part of gfs2_ondisk.h: the ondisk metadata specification.  This is a bit
> unusual since gfs uses a hash table on-disk for its directory structure.
> This header, including the hash function/table, must be included by user
> space programs like fsck that want to decipher a fs, and any change to the
> function or table would effectively make the fs corrupted.  Because of
> this I think it's best for gfs to keep it's own copy as part of its ondisk
> format spec.

for userspace there's libcrc32 as well. If it's *the* bog standard crc32
I don't see a reason why your "spec" can't just reference that instead.
And esp in the kernel you should just use the in kernel one not your own
regardless; you can assume the in kernel one is optimized and it also
keeps size down.