On Sun 13-08-17 02:25:56, Christoph Hellwig wrote:

On Sat, Aug 12, 2017 at 07:44:14PM -0700, Dan Williams wrote:

quoted

How about MAP_SYNC == (MAP_SHARED|MAP_PRIVATE)? On older kernels that
should get -EINVAL, and on new kernels it means SYNC+SHARED.

Cute trick, but I'd hate to waster it just for our little flag.

How about:

#define __MAP_VALIDATE		MAP_SHARED|MAP_PRIVATE
#define MAP_SYNC		0x??? | __MAP_VALIDATE

so that we can reuse that trick for any new flag?

Heh, that's such an ugly hack that it is cute ;)... I'll use this
definition of MAP_SYNC in my patches and send new version of the series
(probably today in the afternoon if the testing goes fine).

								Honza

-- 
Jan Kara [off-list ref]
SUSE Labs, CR