64-bit quotas and preparations for OCFS2 quotas

Hello,

the set of patches which will come in following emails implements 64-bit quotas support and also does some cleanups and necessary changes for quota support in OCFS2.
64-bit quota support implements new version of quota disk format (which
shares most of the code with current quota format) so quota is no longer limited by 4 TB space limits and 2^32 inode limit and usage (guys from Sun seem to have problems with this ;).
OCFS2 quota support needs some changes to the internal quota code since
it treats quota data as filesystem metadata - quota code does not have to care about problems with accesses to quota files from userspace, but it has to allow separate enabling of usage accounting and limits enforcement.
Andrew, could you please put these patches to -mm for testing? Thanks.
Eventually, the patches (except for the last one implementing 64-bit quota format specific functions) are probably going to hit linux-next via ocfs2 git tree but I guess that's not a problem.

Honza