On Tue, Sep 30, 2014 at 10:44 PM, Linus Torvalds <[email protected]> wrote: > On Tue, Sep 30, 2014 at 12:19 PM, Miklos Szeredi <[email protected]> wrote: >> >> What about flock(2), FL_SETLEASE, etc semantics (which are the sane ones, >> compared to the POSIX locks shit which mandates release of lock on each >> close(2) >> instead of "when all [duplicate] descriptors have been closed")? >> >> You have to do that from ->release(), there's no question about that. > > We do locks_remove_file() independently on ->release, but yes, it's > basically done just before the last release. > > But it has the *exact* same semantics as release, including very much > having nothing what-so-ever to do with "last close()". > > If the file descriptor is opened for other reasons (ie mmap, /proc > accesses, whatever), then that delays locks_remove_file() the same way > it delays release. > > None of that has *anothing* to do with "synchronous". Thinking it does is > wrong.
Oh, and btw. nfsv4 has a synchronous ->release implementation. Probably for exactly the same reason Anand and Maxim wants it in their server. Note: locks_remove_file() works for local locking, but distributed filesystems need to release locks and leases in their ->release. And yes, /proc does temporary ref of file. But it's an implementation detail, and should be fixable. As to mmap, it's almost like dup(2) regarding the file, we could actually handle it that way and have a flush at munmap time too. Thanks, Miklos -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
