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From: "J. Bruce Fields" <bfields@fieldses.org>
To: Jeremy Allison <jra@samba.org>
Cc: Volker Lendecke <Volker.Lendecke@SerNet.DE>,
	linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	samba-technical@lists.samba.org,
	Casey Bodley <cbodley@citi.umich.edu>
Subject: Re: [PATCH] locks: breaking read lease should not block read open
Date: Fri, 19 Aug 2011 12:04:16 -0400	[thread overview]
Message-ID: <20110819160416.GC30856@fieldses.org> (raw)
In-Reply-To: <20110729022758.GC20317@fieldses.org>

On Thu, Jul 28, 2011 at 10:27:58PM -0400, J. Bruce Fields wrote:
> On Thu, Jul 21, 2011 at 12:35:20PM -0400, J. Bruce Fields wrote:
> > On Wed, Jul 20, 2011 at 05:15:42PM -0700, Jeremy Allison wrote:
> > > On Wed, Jul 20, 2011 at 08:07:58PM -0400, J. Bruce Fields wrote:
> > > > So it's a question about the protocols samba implements:
> > > > 
> > > > 	- Do they allow an atomic downgrade from an exclusive to a
> > > > 	  shared oplock?  (Or to a level 2 oplock, or whatever the right
> > > > 	  term is).
> > > 
> > > Yes. Exclusive can go to level 2 - in fact that's the default
> > > downgrade we do (unless an smb.conf option explicity denies it).
> > > 
> > > > 	- If so, can that happen as a response to a conflicting open?
> > > > 	  (So, if you're holding an exclusive oplock, and a conflicting
> > > > 	  open comes in, can the server-to-client break message say "now
> > > > 	  you're getting a shared oplock instead"?  Or is the client
> > > > 	  left without any oplock until it requests a new one?)
> > > 
> > > Yes, this can happen.
> > > 
> > > In SMB, we only break to no lease when a write request comes
> > > in on a exclusive or level2 oplock (read-lease) handle.
> > 
> > Ok, thanks, that means we need a more complicated fix here--I'll work on
> > that....
> 
> My attempt follows.  Lightly tested.
> 
> I'll probably try writing a test or two for it, then queueing up
> something like this for 3.2, absent objections.

Second take follows, this time after a little more testing
(lease_tests.c from git://linux-nfs.org/~bfields/lock-tests.git), some
bug fixes, and minor simplification of the logic.  This is what I intend
to queue up for 3.2.

--b.

  parent reply	other threads:[~2011-08-19 16:04 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-06-09 23:16 [PATCH] locks: breaking read lease should not block read open J. Bruce Fields
2011-06-10  7:56 ` Volker Lendecke
2011-06-10 13:48   ` J. Bruce Fields
2011-07-21  0:07     ` J. Bruce Fields
2011-07-21  0:15       ` Jeremy Allison
2011-07-21 16:35         ` J. Bruce Fields
2011-07-29  2:27           ` J. Bruce Fields
2011-07-29  2:29             ` [PATCH 1/3] locks: minor lease cleanup J. Bruce Fields
2011-07-29  2:29               ` [PATCH 2/3] locks: move F_INPROGRESS from fl_type to fl_flags field J. Bruce Fields
2011-07-29  2:30                 ` [PATCH 3/3] locks: fix tracking of inprogress lease breaks J. Bruce Fields
2011-08-19 16:04             ` J. Bruce Fields [this message]
2011-08-19 16:07               ` [PATCH 1/4] locks: minor lease cleanup J. Bruce Fields
2011-08-19 16:07               ` [PATCH 2/4] locks: move F_INPROGRESS from fl_type to fl_flags field J. Bruce Fields
2011-08-19 16:07               ` [PATCH 3/4] locks: fix tracking of inprogress lease breaks J. Bruce Fields
2011-08-19 16:07               ` [PATCH 4/4] locks: setlease cleanup J. Bruce Fields
2011-08-19 19:08       ` [PATCH] locks: breaking read lease should not block read open Jamie Lokier
2011-08-21 16:50         ` J. Bruce Fields
2011-11-21 12:46           ` Jamie Lokier
2011-11-22 21:44             ` J. Bruce Fields
2011-11-23  0:30               ` Jamie Lokier
2011-11-23 19:08                 ` J. Bruce Fields

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