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? Is /etc/sysconfig/nfs read upon reboot? -->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
