2011/10/4 J. Bruce Fields <bfields@xxxxxxxxxxxx>: > On Tue, Oct 04, 2011 at 06:54:51AM -0400, Jeff Layton wrote: >> I think this is tantamount to insisting that applications be specially >> written for cifs.ko if they want to do locking. >> >> The larger goal for cifs.ko (as I see it) is to allow applications to >> mostly run unchanged on top of windows servers. Naturally, this is >> impossible since windows doesn't follow POSIX semantics, so the best we >> can do is closely approximate it. >> >> There's certainly room for improvement here, but what you're proposing >> sounds like a step backward from that goal. It will break a lot of >> existing applications that run successfully on top of cifs.ko today. > > Right. You can tell which kind of locking the application wants by the > interface it's using. If the application is using fcntl F_GETLK, > F_SETLK, F_SETLKW, then chances are it was written assuming posix > semantics, so all we can do is emulate those as best as possible. > > If there are applications that need want the Windows semantics, then > we'd need to provide a new lock interface which promises them exactly > that. > > --b. > Ok, I understand your and Jeff's idea - it's better to support POSIX at least partly than doesn't support it at all. I don't think that we need VFS changes for the new mode, because it is cifs feature only. All that we need is to support this for cifs - so, it can be a new mount option or the existing one - now we have 'forcemand' mount option (that switch on mandatory locking even if the server support POSIX one) that can includes such a change. What do you think about it? -- Best regards, Pavel Shilovsky. -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
