[PATCH] locks: breaking read lease should not block read open

[J. Bruce Fields]

On Fri, Jun 10, 2011 at 09:56:49AM +0200, Volker Lendecke wrote:
> On Thu, Jun 09, 2011 at 07:16:06PM -0400, J. Bruce Fields wrote:
> > The lease code behavior during the lease-breaking process is strange.
> > Fixing it completely would be complicated by the fact that the current
> > code allows a lease break to downgrade the lease instead of necessarily
> > removing it.
> > 
> > But I can't see what the point of that feature is.  And googling around
> > and looking at the Samba code, I can't see any evidence that anyone uses
> > it.  Think we could just do away with removing the ability to downgrade
> > to satisfy a lease break?
> 
> Without having looked too deeply, just let me point out that
> Samba here has a plain flaw. Early Linux Kernel versions
> that we programmed against did not properly support read
> only leases, so we did not implement that initially. If I
> remember correctly we never got around to finally do it once
> it became available. Eventually we will probably, as read
> only leases are a pretty important feature to present to
> CIFS clients.

Thanks, I didn't know that.  (Or I did, and I forgot.)

When you *do* implement that, is there any chance you'd have this need
to be able to downgrade to a read lease in the case of a conflict?

--b.