lkml.org 
[lkml]   [1999]   [Apr]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: Quota file format [2.3 issue]
      Hello.
    >
    > I recently realized the format of quota.user and quota.group 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.).
    [snip]
    > 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...).

    Honza.


    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.rutgers.edu
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-03-22 13:51    [W:0.024 / U:0.120 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site