On 04/25/2016 07:48 AM, Christoph Hellwig wrote:
On Thu, Apr 21, 2016 at 02:15:24PM -0400, Waiman Long wrote:
On 04/20/2016 04:58 PM, Christoph Hellwig wrote:
FYI, none of the Dax code even needs to ever touch the dio_count,
as dax I/O can't be asynchronous, and we thus don't need it to protect
against truncate. I'd suggest to remove it and then end_io callback
>from the DAX code entirely as a start and then move from there.
Yes, it seems like we may not need to change the dio_count in dax_do_io()
after all. BTW, what do mean by using end_io callback as a start?
I mean to remove both the i_dio_count manipulation, and the unessecary
end_io callback from dax_do_io.
Thanks for the clarification.
Since DAX I/O is always synchronous, the locking done by the caller or
in the dax_do_Io() for read should be enough to prevent truncation from
happening at the same time. So we don't need to use i_dio_count for that
purpose.
However, I have not understood enough of the block IO layer to determine
if the end_io callback is really redundant. I am not confident enough to
touch the end_io callback.
Cheers,
Longman
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