On Sat, Dec 20, 2014 at 06:51:33AM +0000, Al Viro wrote: > > The problem is that the use of ->direct_IO by the swap code is a gross > > layering violation. ->direct_IO is a callback for the filesystem, and > > the swap code need to call ->read_iter instead of ->readpage and > > ->write_tier instead of ->direct_IO, and leave the locking to the > > filesystem. > > The thing is, ->read_iter() and ->write_iter() might decide to fall back to > buffered IO path. XFS is unusual in that respect - there O_DIRECT ends up > with short write in such case. Other filesystems, OTOH...
We'll just need a ->swap_activate method that makes sure we really do direct I/O. For all filesystems currently suporting swap just checking that all blocks are allocated (as the ->bmap path already does) should be enough. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
