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

-- 

"Glory is fleeting, but obscurity is forever."  
         - Napoleon Bonaparte

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