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    SubjectRe: 2.6.17-rc5-mm3-lockdep - locking error in quotaon

    * Jan Kara <jack@suse.cz> wrote:

    > > but that doesn't quite match your description...
    > This piece of code is there just because we avoid page cache when
    > doing quota writes. That is a different story and should cause problems
    > with your lock checker.
    > Standard way of running quota is:
    > - get i_mutex for data_inode
    > - write some data to data_inode
    > - requires allocation -> calls DQUOT_ALLOC_SPACE
    > - DQUOT_ALLOC_SPACE acquires some quota locks, decides it wants to
    > write out quota structure (e.g. because we are journaling quota and
    > must preserve quota integrity)
    > - acquires dqio_sem, calls filesystem specific quota writing
    > function - e.g. ext3_quota_write()
    > - this function acquires i_mutex for quota file
    >
    > I think this is the type of circle your checker has found.

    the validator noticed a circular dependency (AB->BA, or AB->BC->CA,
    etc.) - while the nesting above it would report as: "BUG: possible
    deadlock detected!".

    Ingo
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