On Thu, 2009-02-12 at 14:11 -0600, Nicolas Williams wrote: > On Thu, Feb 12, 2009 at 03:00:51PM -0500, David P. Quigley wrote: > > We also explored a callback for label change notification. I think we > > even have the code lying around for the prototype. It worked but Trond > > expressed some concern with how well it would scale. The issue Trond > > raised is what happens if you relabel an entire file system from under a > > set of NFSv4 clients? I'm not sure how much of a concern this will be > > Surely it would scale no better and no worse than open file delegation... > > > since 1) File relabeling is supposed to be rare and 2) clients will > > probably have a small subset of files open. In the event that you do > > Reclassification of data is supposed to be rare, though that may vary a > lot by environment. The number of files that may be kept open provides > a natural limit to how many relabel callbacks will be needed. (A client > could OPEN every file at limit cost to itself hoping to overwhelm a > server, but that's a separate issue.) > > > need to relabel the entire file system on the server it might be a good > > idea from an administrative perspective to have your clients remount the > > NFS shares and flush whatever caches they have. > > Well, there's no callback to tell clients to flush all writes and > remount (or recover). You could simulate a server reboot and force > recovery though. > > Nico So can anyone see of another use for providing a call back that would tell a client to flush it's cached changes back to the server and start a recovery? It could be a potential solution to large scale relabeling on the server but I hesitate to propose it unless it has more than just that application. Also aren't callbacks done out of band and if a callback channel can't be established the functionality is just dropped? Dave -- This message was distributed to subscribers of the selinux mailing list. If you no longer wish to subscribe, send mail to majordomo@xxxxxxxxxxxxx with the words "unsubscribe selinux" without quotes as the message.
