> On May 26, 2016, at 9:54 AM, Andy Adamson <androsadamson@xxxxxxxxx> wrote: > > On Wed, May 25, 2016 at 2:55 PM, Chuck Lever <chuck.lever@xxxxxxxxxx> wrote: >> >>> On May 25, 2016, at 2:48 PM, bfields@xxxxxxxxxxxx wrote: >>> >>> On Wed, May 25, 2016 at 05:29:35PM +0000, Adamson, Andy wrote: >>>> Anna Schumaker who reviewed my client side session trunking patchset, wants a full featured version of both the client and the server session trunking pieces before accepting the session trunking feature upstream. To that end, I want to implement the server mountd V4ROOT processing of an fs_locations configuration to satisfy an fs_locations request on the pseudo fs. >>>> >>>> The forwarded message is from an email stream between Bruce, Chuck and I concerning the server pseufo fs fs_locations configuration that I’m now sharing with the list. >>>> >>>> Some background: >>>> >>>> The recent "NFSV4.1,2 session trunking” Version-5 patch set sent to the list notes (in patch 00/10): >>>> >>>> The pseudo-fs GETATTR(fs_locations) probe session trunking >>>> was tested against a Linux server with a pseudo-fs >>>> export stanza (e.g. a stanza with the fsid=0 or fsid=root >>>> export option) and a replicas= export option >>>> (replicas=<path1>@<server1>:<path2>@<server2>..) >>>> Note that this configuration is for testing only. A future >>>> patchset will add the replicas= configuration to the >>>> NFSEXP_V4ROOT nfsd and mountd processing. >>>> >>>> >>>> There are several ideas on how to accomplish mountd/V4ROOT fs_locations configuration in the forwarded message. See inline. >>>> >>>> >>>>> Begin forwarded message: >>>>> >>>>> From: Chuck Lever <chuck.lever@xxxxxxxxxx> >>>>> Subject: Re: Configuring fs_locations on Linux upstream server >>>>> Date: May 6, 2016 at 4:31:00 PM EDT >>>>> To: "J. Bruce Fields" <bfields@xxxxxxxxxxxx> >>>>> Cc: "Adamson, Andy" <William.Adamson@xxxxxxxxxx> >>>>> >>>>> >>>>>> On May 6, 2016, at 4:16 PM, J. Bruce Fields <bfields@xxxxxxxxxxxx> wrote: >>>>>> >>>>>> On Fri, May 06, 2016 at 02:20:12PM -0400, Chuck Lever wrote: >>>>>>> Seems like when a server does not return a list, that is >>>>>>> information the client can use: basically, there is no >>>>>>> ability to do any session trunking. It has to be set up >>>>>>> explicitly; is that a bad thing, operationally? >>>>>> >>>>>> I like the idea of it being opt in on the server. >>>>>> >>>>>> Suppose the server transparently starts advertising all available >>>>>> addresses for session trunking. It's not hard to imagine cases where >>>>>> that would go wrong. E.g., maybe the server has the odd wireless or >>>>>> 100Mb or other interface that happens to work but that's slow. Then >>>>>> somebody upgrades their server and performance goes down and it may take >>>>>> them a while to figure out why. Whereas if they'd had to opt in they'd >>>>>> probably have avoided advertising an inappropriate interface. Or at >>>>>> least they'd have a better chance of figuring out that turning on >>>>>> trunking was what caused the problem. >>>>>> >>>>>> I'd rather not force people to export "/" explicitly, though. It's fine >>>>>> for testing, but: >>>>>> >>>>>> - I don't think we give a way to do an explicit V4ROOT export, >>>>>> so they'd be exposing their entire root partition. We could >>>>>> fix that, but >>>>>> - the pseudofs just seems to me like something people shouldn't >>>>>> normally have to think about. It's a protocol implementation >>>>>> detail, I'd rather hide it. It'd be to easy to configure it a >>>>>> little wrong, I think. >>>>>> >>>>>> We can still do this by adding a replicas= option to the / export, but >>>>>> we can let rpc.mountd do that internally instead of making the admin add >>>>>> it to /etc/exports. >>>>>> >>>>>> But then you still need a way for the admin to tell rpc.mountd to cook >>>>>> up the replicas= option..... I'm not sure what that should look like. >>>> >>>> Idea 1: extra syntax in /etc/exports >>> >>> It's not really export-specific information. I wonder if it'd be better >>> to pass it on the rpc.nfsd commandline? >>> >>> rpc.nfsd --multipath-set="192.168.0.1,192.168.0.2" >>> >>> (and then that can be configured in /etc/sysconfig/nfs or whatever)? > > Is this (the rpc.nfsd command line and /etc/sysconfig/nfs entry) the > preferred way? I don't prefer it. See below: I think we want something that is more convenient to update automatically. > Is /etc/sysconfig/nfs read upon reboot? It's read by all the start-up scripts related to NFS. > -->Andy > > > >>> >>>>>> Maybe some extra syntax in /etc/exports, but what do they need to give >>>>>> us--just one list of IP addresses? Chuck, any ideas? >>>> >>>> Idea 2: xattr attached to “/" >>>> >>>>> >>>>> How about using the same approach used for junctions: >>>>> put the list in an xattr attached to / ? mountd can >>>>> extract that when the kernel asks for help satisfying >>>>> a GETATTR(fs_locations) on V4ROOT. >>> >>> I don't think that works. "/" isn't a good place to put configuration. >>> It could be read-only, among other things. >>> >>>> Idea 3: new /etc/ config file >>>>> >>>>> Or it could be put in a separate config file in /etc. >>>>> You might want to specify more than just the i/f list >>>>> here; for instance, the security policy for the >>>>> pseudofs, or a constant fsid UUID, among other things. >>>> >>>> >>>> API to update the i/f list. This is not about where to hold fs_locations config info, but rather how to insert the (changed) info into the running system. >>>> >>>>> >>>>> Also, I suggested to Andy earlier: >>>>> >>>>>> I find myself leaning towards mechanisms that are easy >>>>>> both for admins and for programs (ie, an API). Perhaps >>>>>> one day you might want to add a command that updates the >>>>>> i/f list from the scripts in /etc/sysconfig/network-scripts, >>>>>> for instance. >>>>>> >>>>>> As part of an ifup: >>>>>> >>>>>> nfspfs add <addr> >>>>>> >>>>>> and ifdown: >>>>>> >>>>>> nfspfs remove <addr> >>>>>> >>>>>> I wrote some Python code to manipulate entries in >>>>>> /etc/exports, now found in fedfs-utils. It's icky. >>>>> >>>>> I think we should move away from "edit this file >>>>> and save it, then restart rpc.xyzpdq". Build some >>>>> command line interfaces for this. >>> >>> I'm OK with that. >>> >>> (Note do have that for information in /etc/exports--we have exportfs. >>> Is there a reason that didn't work for fedfs-utils?) >> >> To make changes that can survive a server reboot, >> you have to update /etc/exports. >> >> >>> --b. >>> >>>>> >>>>> And as you have suggested many times: separate >>>>> policy from mechanism. /etc/exports is the >>>>> mechanism. >>>>> >>>>> -- >>>>> Chuck Lever >>>> >>>> Bruce - do you have a preference between #1 and #2 or #3 (or another idea?) >>>> >>>> Thanks >>>> >>>> —>Andy >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in >>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >> >> -- >> Chuck Lever >> >> >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> 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@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Chuck Lever -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
