On Tue, Dec 15, 2009 at 05:27:29PM +1100, Neil Brown wrote: > On Fri, 4 Dec 2009 20:17:42 -0500 > "J. Bruce Fields" <bfields@xxxxxxxxxxxx> wrote: > > > > > > > How about this as an alternate. I have only compile tested it, nothing more. > > > But if it looks good to you I'll make sure it really works. > > > > Well, without having really thinking about it: > > > > - If this were two separate patches, I'd have an easier time > > sorting out the interesting stuff from the trivial (though > > nevertheless good) hash-function reshuffling. > > I'll see what I can come up with... Have you had a chance to get back to this? > > > - Adding code to the common lookup_and_check() instead of to > > every caller certainly seems better, but too bad about the > > special cases that remain. > > yeah.... I could possibly add a pass-by-reference to lookup_and_check > which points to a possible cached value, but that would have > only one user, so the special case would be moved elsewhere... > ?? Yeah, that doesn't sound so great. > > - Something still seems odd here: we shouldn't ever have > > duplicate cache entries with the same key, because during > > their lifetimes cache entries are always kept in the hash. So > > why do we need extra code to check for that case? I may just > > be forgetting what we're doing here. Should I go reread the > > rest of the series? > > When sunrpc_update_cache is called to update and item that is > already valid, it unhashes that item and creates a new one. > (The unhashed item disappears once all the refcounts go). > So if we wait for user-space to update an entry for us, we > might find out that it has been unhashed, so we need to find > the new one. But nobody ever waits on a valid entry, right? So isn't the only case we care about the invalid case? I'll admit I haven't thought this through. --b. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
