> On Thu, Feb 21, 2013 at 12:02:18PM +0000, Dietmar Maurer wrote: > > > The problem is about cache coherency. Local files work just fine > > > with cache=writeback, but if you migrate to a different host, you > > > get the problem that the destination kernel may cache some parts of > > > the image while the source is still writing to it. When you do the > > > actual switch to the destination host and the backend doesn't take > > > care of invalidating that cache, you might (partially) read outdated data. > > > > Isn't there a way to force a cache flush? > > Forcing the caches for a single file to be dropped? Not that I'm aware of (or > anyone else who looked into the problem before we decided to document > cache=none as a requirement).
What happens if you open a file with O_DIRECT first, the reopen with other flags? Would that flush the cache?
