On 30 Jul 2021, at 10:48, Trond Myklebust wrote: > On Fri, 2021-07-30 at 09:25 -0400, Benjamin Coddington wrote: >> I have some folks unhappy about behavior changes after: 479219218fbe >> NFS: >> Optimise away the close-to-open GETATTR when we have NFSv4 OPEN >> >> Before this change, a client holding a RO open would invalidate the >> pagecache when doing a second RW open. >> >> Now the client doesn't invalidate the pagecache, though technically >> it could >> because we see a changeattr update on the RW OPEN response. >> >> I feel this is a grey area in CTO if we're already holding an open. >> Do we >> know how the client ought to behave in this case? Should the >> client's open >> upgrade to RW invalidate the pagecache? >> > > It's not a "grey area in close-to-open" at all. It is very cut and > dried. > > If you need to invalidate your page cache while the file is open, then > by definition you are in a situation where there is a write by another > client going on while you are reading. You're clearly not doing close- > to-open. > > The people who are doing this should be using uncached I/O. Thanks Trond, that corrects my ambiguity and yes - there's a much better way. Ben
