On Sun, Apr 13, 2008 at 10:28:08AM +0200, Miklos Szeredi wrote: > > Apologies, that was indeed a behavioral change introduced in a commit > > that claimed just to be shuffling code around. > > Another complaint about this series: using EINPROGRESS to signal > asynchronous locking looks really fishy. How does the filesystem > know, that the caller wants to do async locking? The caller sets a fl_grant callback. But I guess the interesting question is how the caller knows that the filesystem is really going to return the results asynchronously: > How do we make sure, > that the filesystem (like fuse or 9p, which "blindly" return the error > from the server) doesn't return EINPROGRESS even when it's _not_ doing > an asynchronous lock? Right, there's no safeguard there--if fuse returns EINPROGRESS, then we'll wait for a grant callback that's not going to come. It should time out, so that's not a total disaster, but still. Anyway, I'm not sure what to do about that. > > I think it would have been much cleaner to have a completely separate > interface for async locking, instead of trying to cram that into > f_op->lock(). Maybe so. ->lock() had quite a bit crammed into it even before this. > Would that be possible to fix now? Or at least make EINPROGRESS a > kernel-internal error value (>512), to make it that it has a special > meaning for the _kernel only_? Perhaps so. The behavior of lockd will still depend to some degree on the exact error returned from the filesystem--e.g. if you return -EAGAIN from ->lock() without later calling ->fl_grant() it will cause some unexpected delays. (Though again clients will eventually give up and poll for the lock.) --b. -- 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
