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    SubjectRe: 2.4.20pre5aa1
    On Thu, Sep 05, 2002 at 06:09:04PM +0100, Christoph Hellwig wrote:
    > On Thu, Sep 05, 2002 at 06:53:07PM +0200, Andrea Arcangeli wrote:
    > > btw, even if xfs is applied before the inode_read_write-atomic, please
    > > make sure xfs will learn using the i_size_read when out of the semaphore
    > > and i_size_write too. I know the locking is different there but I doubt
    > > you're just managing the i_size without races.
    >
    > XFS always has the XFS i_lock around accessing it. Either in read mode
    > or in write mode for updates (the lock is a so-called mrlock which
    > basically as a rwsem with a few subtile differences).
    >
    > Anyway most acceses i_size in the new code are done by the generic
    > code now as XFS calls it internally. Take a look at the update I sent
    > you a few seconds ago :)

    maybe I'm overlooking something but after a short read it seems you have
    no lock in do_truncate->setattr like for all the other fs, so the
    vmtruncate can run under reads and the i_size can change under you and
    in turn you must always read it with i_size_read using asm, like all the
    other fs, if you're not holding the i_sem (and you certainly aren't
    holding the i_sem that frequently, you don't even for writes). this
    because i_sem is the only lock/sem hold by truncate. Infact I'm unsure
    how you serialize the i_size writes of truncate against the ones from
    writes, that seems problematic too, the i_size could get a value past
    the last block allocated (in turn corrupting the fs). Please double
    check that I'm wrong, thanks.

    Andrea
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