Return-Path: Received: from fieldses.org ([174.143.236.118]:52285 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754591Ab1HDQtO (ORCPT ); Thu, 4 Aug 2011 12:49:14 -0400 Date: Thu, 4 Aug 2011 12:49:13 -0400 From: "J. Bruce Fields" To: Frank van Maarseveen Cc: Linux NFS mailing list Subject: Re: [NLM] fcntl(F_SETLKW) yields -ENOLCK when grace period expires. Message-ID: <20110804164913.GG12445@fieldses.org> References: <20110804103018.GA11727@janus> <20110804163452.GE12445@fieldses.org> <20110804164313.GA17572@janus> Content-Type: text/plain; charset=us-ascii In-Reply-To: <20110804164313.GA17572@janus> Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 On Thu, Aug 04, 2011 at 06:43:13PM +0200, Frank van Maarseveen wrote: > On Thu, Aug 04, 2011 at 12:34:52PM -0400, J. Bruce Fields wrote: > > On Thu, Aug 04, 2011 at 12:30:19PM +0200, Frank van Maarseveen wrote: > > > Both client- and server run 2.6.39.3, NFSv3 over UDP (without the > > > relock_filesystem patch proposed earlier). > > > > > > A second client has an exclusive lock on a file on the server. The > > > client under test calls fcntl(F_SETLKW) to wait for the same exclusive > > > lock. Wireshark sees NLM V4 LOCK calls resulting in NLM_BLOCKED. > > > > > > Next the server is rebooted. The second client recovers the lock > > > correctly. The client under test now receives NLM_DENIED_GRACE_PERIOD for > > > every NLM V4 LOCK request resulting from the waiting fcntl(F_SETLKW). When > > > this changes to NLM_BLOCKED after grace period expiration the fcntl > > > returns -ENOLCK ("No locks available.") instead of continuing to wait. > > > > So that sounds like a client bug, and correct behavior from the server > > (assuming the second client was still holding the lock throughout). > > yes. > > > > > > server:/proc/locks shows two entries for the file after the -ENOLCK. When > > > the second client gives up its lock because the program running there > > > is killed one entry in server:/proc/locks remains indefinately: as a > > > result no NFS client can lock the file anymore. > > > > But that sounds like a server bug--what do the two entries look like? > > I think the server assumes correct client behavior; the client under > test resulted in a '->' prefixed entry. The fcntl at the client just > shouldn't have returned yet. Oh, right, so did you see a granted callback returned to the client? --b. > > > > > Also, what filesystem are you exporting? > > ext4 > > -- > Frank