Re: [PATCH 18/18] xfs: recall pNFS layouts on conflicting access

Dave Chinner
2015-01-06T23:35:37Z

On Tue, Jan 06, 2015 at 05:28:41PM +0100, Christoph Hellwig wrote:
> Recall all outstanding pNFS layouts and truncates, writes and similar extent
> list modifying operations.

This is not sufficient to isolate extent manipulations. mmap writes
can trigger allocation through ->page_mkwrite, and can also trigger
extent conversion at IO completion without first needing allocation.

Maybe I'm missing something - this patchset needs some comments
documenting the locking used in XFS to co-ordinate layout coherency
at the client side with IO that is in progress for clients with
overlapping block maps, as well as against server side application
IO.

Cheers,

Dave.
--
Dave Chinner
david@fromorbit.com