On Mon, 2021-06-28 at 15:49 -0400, J. Bruce Fields wrote: > Is there anything analogous to a "shrinker", but for disk space? So, > some hook that a filesystem could call to say "I'm running out of > space, > could you please free something?", before giving up and returning > ENOSPC? > > The NFS server currently revokes a client's state if the client fails > to > contact it within a lease period (90 seconds by default). That's > harsher than necessary--if a network partition lasts longer than a > lease > period, but if nobody else needs that client's resources, it'd be > nice > to be able to hang on to them so that the client could resume normal > operation after the network comes back. So we'd delay revoking the > client's state until there's an actual conflict. But that means we > need > a way to clean up the client as soon as there is a conflict, to avoid > unnecessarily failing operations that conflict with resources held by > an > expired client. > > At first I thought we only needed to worry about file locks, but then > I > realized clients can also hold references to files, which might be > unlinked. I don't want a long-expired client to result in ENOSPC to > other filesystem users. > > Any ideas? > How about just setting up a notification for unlink on those files, the same way we set up notifications for close with the NFSv3 filecache in nfsd? > I searched around and found this discussion of volatile ranges > https://lwn.net/Articles/522135/, which seems close, but I don't know > if > anything came of that in the end. > > --b. -- Trond Myklebust Linux NFS client maintainer, Hammerspace trond.myklebust@xxxxxxxxxxxxxxx
