On Mon, Jun 20, 2011 at 04:15:39PM -0400, Christoph Hellwig wrote:
> Maintain i_dio_count for all filesystems, not just those using DIO_LOCKING.
> This these filesystems to also protect truncate against direct I/O requests
> by using common code. Right now the only non-DIO_LOCKING filesystem that
> appears to do so is XFS, which uses an opencoded variant of the i_dio_count
> scheme.
>
> Behaviour doesn't change for filesystems never calling inode_dio_wait,
> which are all that never use DIO_LOCKING.
>
> For ext4 behaviour changes with the dioread_nonlock option, which previous
> was missing any protection between truncate and direct I/O reads.
>
> For ocfs2 that handcrafted i_dio_count manipulations are replaced with
> the common code noew available.
Oh god you're making the world scary. Are you guaranteeing that
all allocation changes are locked out by the time we get into
file_aio_write() and file_aio_read()? This is not obvious to me.
Joel
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