From: Olga Kornievskaia Subject: Re: [PATCH] nfsd: use nfs client rpc callback program Date: Fri, 19 Sep 2008 15:51:04 -0400 Message-ID: <48D402A8.7020006@citi.umich.edu> References: <48D15DF0.4000406@panasas.com> <20080917231018.GA5723@fieldses.org> <48D193EE.2020805@panasas.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Cc: "J. Bruce Fields" , linux-nfs@vger.kernel.org, pnfs mailing list , Fred Isaman To: Benny Halevy Return-path: Received: from citi.umich.edu ([141.211.133.111]:27381 "EHLO citi.umich.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752176AbYISUX4 (ORCPT ); Fri, 19 Sep 2008 16:23:56 -0400 In-Reply-To: <48D193EE.2020805@panasas.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: Benny Halevy wrote: > On Sep. 17, 2008, 18:10 -0500, "J. Bruce Fields" wrote: > >> On Wed, Sep 17, 2008 at 02:43:44PM -0500, Benny Halevy wrote: >> >>> From: Benny Halevy >>> >>> since commit ff7d9756b501744540be65e172d27ee321d86103 >>> "nfsd: use static memory for callback program and stats" >>> do_probe_callback uses a static callback program >>> (NFS4_CALLBACK) rather than the one set in clp->cl_callback.cb_prog >>> as passed in by the client in setclientid (4.0) >>> or create_session (4.1). >>> >> Ugh, yes, sorry about that. (I wonder why pynfs testing didn't catch >> this? Oh, I guess it's because NFS4_CALLBACK is the program number our >> client always gives us.) >> > > Well, Fred (thanks!) added a test today which uses a non-default > callback program and he sees a corresponding callback coming back. > > (Note that this test is not absolutely generic as the server is > not required to probe the callback immediately, or at all, after > setclientid or create_session.) > > >>> @@ -371,6 +356,8 @@ static int do_probe_callback(void *data) >>> .to_maxval = (NFSD_LEASE_TIME/2) * HZ, >>> .to_exponential = 1, >>> }; >>> + static struct rpc_stat cb_stats; >>> + struct rpc_program cb_program; >>> struct rpc_create_args args = { >>> .protocol = IPPROTO_TCP, >>> .address = (struct sockaddr *)&addr, >>> @@ -394,6 +381,20 @@ static int do_probe_callback(void *data) >>> addr.sin_port = htons(cb->cb_port); >>> addr.sin_addr.s_addr = htonl(cb->cb_addr); >>> >>> + /* Initialize rpc_program */ >>> + memset(&cb_program, 0, sizeof(cb_program)); >>> + cb_program.name = "nfs4_cb"; >>> + cb_program.number = clp->cl_callback.cb_prog; >>> + cb_program.nrvers = ARRAY_SIZE(nfs_cb_version); >>> + cb_program.version = nfs_cb_version; >>> + cb_program.stats = &cb_stats; >>> + memset(&cb_stats, 0, sizeof(cb_stats)); >>> + cb_stats.program = &cb_program; >>> >> You don't want a pointer to data on the stack here, do you? >> > > Hmm, you're right... > I went back and forth whether this should be allocated statically, > dynamically, or on the stack. I was mislead by the fact we're doing > a sync rpc call, but indeed this needs to live until the nfs client > is destroyed. I'm trying to fully understand what Olga saw > before coming up with a new proposal... maybe putting the cb_program > back into struct nfs4_callback and just make cb_stats static would > provide a solution of the problem Olga witnessed and keep everybody > happy. > I'm trying really hard to remember what was the issue of not using the structure and instead using static memory. From what I remember the issue was that the memory (clp->cl_callback.cb_prog) was going away.