From: Sev Binello Subject: Re: [NFS] export dir thru 2 diff path names Date: Mon, 10 Nov 2008 14:36:00 -0500 Message-ID: <49188D20.8060009@bnl.gov> References: <491869F0.1000505@bnl.gov> <620E93B2E5CC3B46BD811165E3335B8702F374A0@0461-its-exmb02.us.saic.com> <491882AB.6070908@bnl.gov> <620E93B2E5CC3B46BD811165E3335B8702F37542@0461-its-exmb02.us.saic.com> <4918859C.6080608@bnl.gov> <620E93B2E5CC3B46BD811165E3335B8702F3759D@0461-its-exmb02.us.saic.com> <20081110192820.GC19053@fieldses.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: "Murata, Dennis" , nfs@lists.sourceforge.net To: "J. Bruce Fields" Return-path: Received: from neil.brown.name ([220.233.11.133]:52145 "EHLO neil.brown.name" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750765AbYKJTiB (ORCPT ); Mon, 10 Nov 2008 14:38:01 -0500 Received: from brown by neil.brown.name with local (Exim 4.69) (envelope-from ) id 1KzcZY-0008Kg-MB for linux-nfs@vger.kernel.org; Tue, 11 Nov 2008 06:37:29 +1100 In-Reply-To: <20081110192820.GC19053@fieldses.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: Since on the server side there truly is only 1 export. And clients just access the same export through 2 different names, I expect it would be safe. -Sev ps: But I think I'll wait for a simpler application (less negative ramifications) to test it BTW haven't seen this documented anywhere. J. Bruce Fields wrote: > On Mon, Nov 10, 2008 at 11:28:04AM -0800, Murata, Dennis wrote: > >> That really is the 64K question. During my initial testing, I exported >> the parent directory. Now I am explicitly exporting the installation >> directories, where I see the exportfs message. In the messages log file >> on the server the mount request from the client is always the actual >> directory. >> > > I don't see how this would be "unsafe"--if it works, go for it. > > One potential trap: it's using the same client list and export options > for both, so if you think you can make one of them read-only and one of > them writeable, for example, you'll be disapointed. > > --b. > > >> Wayne >> >> >>> -----Original Message----- >>> From: Sev Binello [mailto:sev-IGkKxAqZmp0@public.gmane.org] >>> Sent: Monday, November 10, 2008 1:04 PM >>> To: Murata, Dennis >>> Cc: J. Bruce Fields; nfs@lists.sourceforge.net >>> Subject: Re: [NFS] export dir thru 2 diff path names >>> >>> Hi - >>> Yeah, I see. >>> So it actually looks like you can do this. >>> I'm not 100% sure if safe --though it looks it -- so I'll >>> probably not use it for this application. >>> >>> Thanks >>> -Sev >>> >>> Murata, Dennis wrote: >>> >>>> That is correct, exportfs only shows the actual directory. >>>> >>> The client >>> >>>> seems to be able to mount the directory with either. >>>> >>>> Wayne >>>> >>>> >>>> >>>>> -----Original Message----- >>>>> From: Sev Binello [mailto:sev-IGkKxAqZmp0@public.gmane.org] >>>>> Sent: Monday, November 10, 2008 12:51 PM >>>>> To: Murata, Dennis >>>>> Cc: J. Bruce Fields; nfs@lists.sourceforge.net >>>>> Subject: Re: [NFS] export dir thru 2 diff path names >>>>> >>>>> Murata, Dennis wrote: >>>>> >>>>> >>>>>> I just tested this on a SL4.7 (RHEL 4.7 variant) using a >>>>>> >>>>>> >>>>> RHEL 4.4 nfs >>>>> >>>>> >>>>>> server. I did get the messages from exportfs about >>>>>> >>>>>> >>>>> duplicate export >>>>> >>>>> >>>>>> entries. On the client I was able to mount both the >>>>>> >>>>>> >>>>> symlink and the >>>>> >>>>> >>>>>> actual directory. They look like separate mounts. There are two >>>>>> entries in /proc/mounts and in /etc/mtab, one with the actual >>>>>> directory path, one with the symlink path. I am using >>>>>> >>>>>> >>>>> autofs to mount >>>>> >>>>> >>>>>> the directories, not hardcoded. Are you using newer >>>>>> >>> distributions? >>> >>>>>> >>>>>> >>>>>> >>>>> I tested on RHEL 4.6. >>>>> Interesting that you can still mount either one. >>>>> On the server an exportfs only shows the real path as exported. >>>>> >>>>> >>>>> >>>>>> What problems will I cause by doing this? I am using the >>>>>> >>>>>> >>>>> symlink path >>>>> >>>>> >>>>>> as the installation path for an application. The idea is a newer >>>>>> version can be installed into a different directory, then after >>>>>> testing the symlink will be changed to the new >>>>>> >>> installation. Other >>> >>>>>> applications that reference the application will always use the >>>>>> symlink path, as well as any user scripts. >>>>>> >>>>>> Wayne >>>>>> >>>>>> >>>>>> >>>>>> >>>>>>> -----Original Message----- >>>>>>> From: linux-nfs-owner@vger.kernel.org >>>>>>> [mailto:linux-nfs-owner@vger.kernel.org] On Behalf Of Sev Binello >>>>>>> Sent: Monday, November 10, 2008 11:06 AM >>>>>>> To: J. Bruce Fields; nfs@lists.sourceforge.net >>>>>>> Subject: Re: [NFS] export dir thru 2 diff path names >>>>>>> >>>>>>> J. Bruce Fields wrote: >>>>>>> >>>>>>> >>>>>>> >>>>>>>> On Mon, Nov 10, 2008 at 10:55:48AM -0500, Sev Binello wrote: >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>>> Well the simplest approach doesn't work. >>>>>>>>> i.e put symb link and actual path in the export file & try >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>> exporting >>>>>>> >>>>>>> >>>>>>> >>>>>>>>> it Exportfs dereferences the link and states that >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>> duplicates are not allowed. >>>>>>> >>>>>>> >>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>> OK, makes sense. >>>>>>>> >>>>>>>> You could mount --bind the filesystem at the other location >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>> instead of >>>>>>> >>>>>>> >>>>>>> >>>>>>>> symlinking. >>>>>>>> >>>>>>>> The filehandles given to the client will be the same >>>>>>>> >>>>>>>> >>>>> across the two >>>>> >>>>> >>>>>>>> exports. If you mount both from the same client, >>>>>>>> >>>>>>>> >>>>> behavior may vary >>>>> >>>>> >>>>>>>> across different clients (for example, as to whether they >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>> attempt to >>>>>>> >>>>>>> >>>>>>> >>>>>>>> share caches between the two), but I think it'd work. >>>>>>>> >>>>>>>> (The question "why??!!??" does come to mind, though.) >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>> Need to make a path change to how file systems are mounted and >>>>>>> exported on the servers This then required a wholesale change to >>>>>>> clients so they mount the correct path. >>>>>>> Not an issue for linux. >>>>>>> But since we don't administer windows pcs and they also >>>>>>> >>> mount the >>> >>>>>>> same file system, wanted to see if we could let them >>>>>>> >>> stay the way >>> >>>>>>> they were for now. >>>>>>> >>>>>>> We're just going to go ahead and have to coordinate this with >>>>>>> windows guys. >>>>>>> >>>>>>> -Sev >>>>>>> >>>>>>> >>>>>>> >>>>>>>> --b. >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>>> -Sev >>>>>>>>> >>>>>>>>> J. Bruce Fields wrote: >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>>> On Fri, Nov 07, 2008 at 12:44:25PM -0500, Sev Binello wrote: >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>>> Can anyone tell me if it's ok to export the same file system >>>>>>>>>>> through 2 different paths ( one is a link) ? >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>> I actually don't know. You could try it and tell us what >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>> you find >>>>>>> >>>>>>> >>>>>>> >>>>>>>>>> out.... >>>>>>>>>> >>>>>>>>>> If you're exporting something *containing* the symlink >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>> and expecting >>>>>>> >>>>>>> >>>>>>> >>>>>>>>>> the client to traverse into the filesystem, be aware that >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>> symlinks >>>>>>> >>>>>>> >>>>>>> >>>>>>>>>> over NFS are actually interpreted (and followed) on the >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>> client--so >>>>>>> >>>>>>> >>>>>>> >>>>>>>>>> they're interpreted as *client-side* paths, not server-side. >>>>>>>>>> >>>>>>>>>> If the path you're exporting is itself a symlink--it probably >>>>>>>>>> depends on how nfs-utils treats symlinks found in >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>> /etc/exports. I'd >>>>>>> >>>>>>> >>>>>>> >>>>>>>>>> have to try it or check the code. >>>>>>>>>> >>>>>>>>>> Another way to export the filesystem in two different >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>> places would >>>>>>> >>>>>>> >>>>>>> >>>>>>>>>> be with mount --bind. >>>>>>>>>> >>>>>>>>>> --b. >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>> -- >>>>>>>>> >>>>>>>>> Sev Binello >>>>>>>>> Brookhaven National Laboratory >>>>>>>>> Upton, New York >>>>>>>>> 631-344-5647 >>>>>>>>> sev-IGkKxAqZmp0@public.gmane.org >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>> -------------------------------------------------------------- >>>>>>> ----------- >>>>>>> This SF.Net email is sponsored by the Moblin Your Move >>>>>>> >>> Developer's >>> >>>>>>> challenge Build the coolest Linux based applications with >>>>>>> >>>>>>> >>>>> Moblin SDK >>>>> >>>>> >>>>>>> & win great prizes Grand prize is a trip for two to an >>>>>>> >>> Open Source >>> >>>>>>> event anywhere in the world >>>>>>> http://moblin-contest.org/redirect.php?banner_id=100&url=/ >>>>>>> _______________________________________________ >>>>>>> NFS maillist - NFS@lists.sourceforge.net >>>>>>> https://lists.sourceforge.net/lists/listinfo/nfs >>>>>>> _______________________________________________ >>>>>>> Please note that nfs@lists.sourceforge.net is being discontinued. >>>>>>> Please subscribe to linux-nfs@vger.kernel.org instead. >>>>>>> http://vger.kernel.org/vger-lists.html#linux-nfs >>>>>>> >>>>>>> -- >>>>>>> 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 >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>> -- >>>>> >>>>> Sev Binello >>>>> Brookhaven National Laboratory >>>>> Upton, New York >>>>> 631-344-5647 >>>>> sev-IGkKxAqZmp0@public.gmane.org >>>>> >>>>> >>>>> >>>>> >>> ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ NFS maillist - NFS@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/nfs _______________________________________________ Please note that nfs@lists.sourceforge.net is being discontinued. 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