On Tue, 2016-05-10 at 00:00 -0700, Christoph Hellwig wrote: > On Mon, May 09, 2016 at 08:02:58AM -0400, Jeff Layton wrote: > > > > AT_FORCE_ATTR_SYNC can be set in flags.????This will require a > > > > network > > > > filesystem to synchronise its attributes with the server. > > > > > > > > AT_NO_ATTR_SYNC can be set in flags.????This will suppress > > > > synchronisation > > > > with the server in a network filesystem.????The resulting > > > > values should be > > > > considered approximate. > > > > > > And what happens if neither is set? > > > > > > > I'd suggest we have the documentation state that the lack of either > > flag leaves it up to the filesystem. In the case of NFS, you'd get > > "normal" attribute cache behavior, for instance which is governed > > by > > the ac* attributes. > > > > We should also note that in the case of something like > > AT_NO_ATTR_SYNC > > on NFS, you might _still_ end up talking to the server if the > > client > > has nothing in-core for that inode. > > File systems specific "legacy" defaults are a bad idea. If we can't > describe the semantics we should not allow them, never mind making > the the default. I'd strongly suggest picking one of the above flags > as the default behavior and only allowing the other as optional flag. > I suspect NO_SYNC is the better one for the flag, as otherwise people > will be surprised once they test their default case on a network > filesystem. Ok, that's a good point. So basically you suggest that xstat should always have FORCE_SYNC semantics unless the NO_SYNC flag is set? Given that we don't need to worry about legacy users with this interface, that seems like a reasonable approach to me. -- Jeff Layton <jlayton@xxxxxxxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
