On Mon, 1 Feb 2010 12:11:48 -0500 "J. Bruce Fields" <bfields@xxxxxxxxxxxx> wrote: > 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? It looks like I did the initial separation in to three patches then promptly went on holiday and forgot about it... I'll get back to it. > > > - 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 an 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. We might wait on a valid entry that has expired (->expiry_time has passed). However we could possibly unlink such entries whenever we find them, then repeat the lookup thus creating a new non-CACHE_VALID entry and wait on that... I see if I can make that work. NeilBrown -- 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
