Messages in this thread | | | Date | Thu, 5 Sep 2002 20:41:25 +0200 | From | Andrea Arcangeli <> | Subject | Re: 2.4.20pre5aa1 |
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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.
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