Return-Path: Received: from 72-48-214-68.dyn.grandenetworks.net ([72.48.214.68]:59215 "EHLO smtp.opengridcomputing.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726027AbeHGX2w (ORCPT ); Tue, 7 Aug 2018 19:28:52 -0400 Subject: Re: NFSv4 file lock reporting interface request To: "J. Bruce Fields" , Cedric Blancher Cc: Peter Scott , Linux NFS Mailing List References: <8dd8a352-aaca-71af-aca7-9be6c7039ff4@jpl.nasa.gov> <20180807203419.GB18415@fieldses.org> From: Tom Tucker Message-ID: Date: Tue, 7 Aug 2018 16:05:42 -0500 MIME-Version: 1.0 In-Reply-To: <20180807203419.GB18415@fieldses.org> Content-Type: text/plain; charset=utf-8; format=flowed Sender: linux-nfs-owner@vger.kernel.org List-ID: Hi Bruce, FWIW, I don't think dtrace does/did what NASA is asking for, but that's really irrelevant. The locks in NFSv4 are application specific locks, not generic kernel locks, so a service looking for spinlocks, mutexes, etc... wouldn't really be helpful I don't think.  However implementing a /sys/class, debugfs thingy that dumped the nfsv4 locks held is fairly simple, although I would think there are security implications. Tom On 8/7/2018 3:34 PM, J. Bruce Fields wrote: > On Thu, Aug 02, 2018 at 08:50:20PM +0200, Cedric Blancher wrote: >> Solaris and FreeBSD dtrace facility supports this functionality. >> Unfortunately, Linux rejected dtrace for license issues, and instead >> did... nothing. > I didn't think was this sort of question tracing was designed to > answer--it's a question about the system state at a given time (who > holds what locks), rather than a list of events. But I know nothing > about dtrace. > > --b. > >> Ced >> >> On 10 July 2018 at 04:28, Peter Scott wrote: >>> Hello. I am with the institutional hosting service at NASA's Jet Propulsion >>> Laboratory and we have been trying to find the answer to an apparently >>> simple question. >>> >>> We are running an NFSv4 server on Centos 7 and we need to get the server to >>> tell us which files it thinks are locked by which clients. This is because >>> we have observed failure modes where something apparently has a lock >>> (because attempting to lock the file again blocks) but we can't find a >>> client that has the lock. Finding out what the server believes would be >>> critical to troubleshooting this. >>> >>> We tracked down Trond Myklebust and Neil Brown and conversation suggests >>> that this is a function that is (a) not currently available and (b) >>> reasonable to ask for. So this is me suggesting that an interface be >>> provided to have knfsd output its list of locked files and clients. >>> >>> Regards, >>> Peter Scott >>> Office of the CIO >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in >>> the body of a message to majordomo@vger.kernel.org >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >> >> >> -- >> Cedric Blancher >> [https://plus.google.com/u/0/+CedricBlancher/] >> Institute Pasteur >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Thomas Tucker President Open Grid Computing, Inc. (m) 512-826-7622 (o) 512-220-3434