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SubjectRe: Quota file format [2.3 issue]
> I recently realized the format of quota.user and is both endian
> and archsize dependant. I think that's very wrong, because when you have a
> nicely portable ext2 filesystem on some disk and you want to move it to
> another computer, you loose if you have quotas on it (in the best case
> quotaon will not succeed and you won't have quotas on it, in the worst case
> it will succeed and do strange things, you'll probably loose all your quota
> information etc.).
> One problem is quota.user is completely header-less and in its whole size
> contains data which can have any value, so it is not easy to distinguish old
> format from some new one. The only thing which comes to my mind is file
> size: current kernel requires quota.user (group) to be non-zero size and
> some multiple of struct dqblk size. That's for sure divisible by 4. So what
> about if we attach a 10 byte header before the whole data lot, which will
> include some magic number and format version, so that's its extensible and
> then follow it by lets say little endian structures with 64bit times.
> That would mean the size of the file is always some multiple of 4 plus 2,
> hence the kernel and utilities can easily find out.
I've also realized this problem when reading quota code. Also we should
be aware of padding of the structure (currently I think there will never
be any padding in the structure but...).
I like the proposed solution and it would be easy to implement it...
Because I'm currently making some fixes in quota code so I can add this feature
too (It will be really only a few lines of code in the kernel...).


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