Re: fcntl(F_GETLEASE) semantics??

[Trond Myklebust <trond.myklebust@fys.uio.no>]

to den 11.08.2005 Klokka 22:23 (+0300) skreiv Heikki Orsila:
> On Thu, Aug 11, 2005 at 03:15:45PM -0400, Trond Myklebust wrote:
> > The difference between inotify and leases is, as I said, that leases
> > notify the lease holder synchronously. This allows the notified process
> > to flush all the cached information _before_ the operation that
> > triggered the lease notification is executed.
> 
> So you're talking about the kernel side.. I was talking about userspace 
> perspective on the syscall. It would be rather odd to let a syscall
> block other applications involuntarily (and thus achieving synchronous 
> action in your meaning)..

No. What I said is true of both kernel space and userspace.

Samba needs the exact same semantics as NFSv4 has: it needs to prevent a
local open() syscall from succeeding while the CIFS clients that hold
oplocks flush their cached information (data, metadata, locks...) back
to the server.

BTW: the blockage is only temporary. If the clients don't respond within
a certain time period (as set by the global
sysctl /proc/sys/fs/lease-break-time) then the lease will be
pre-emptively broken by the kernel.

As I said, this is _very_ different from what inotify does.

Cheers,
  Trond

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