On Tue, 2012-08-07 at 18:26 -0400, Jeff Layton wrote:
> On Tue, 7 Aug 2012 21:23:34 +0000
> "Myklebust, Trond" <Trond.Myklebust@xxxxxxxxxx> wrote:
>
> > On Tue, 2012-08-07 at 16:25 -0400, J. Bruce Fields wrote:
> > > On Tue, Aug 07, 2012 at 04:10:49PM -0400, Bryan Schumaker wrote:
> > > > On 08/07/2012 03:57 PM, J. Bruce Fields wrote:
> > > > > On Tue, Aug 07, 2012 at 03:44:53PM -0400, Bryan Schumaker wrote:
> > > > >> On 08/07/2012 03:42 PM, J. Bruce Fields wrote:
> > > > >>> On Tue, Aug 07, 2012 at 01:09:32PM -0400, Jeff Layton wrote:
> > > > >>>> On Sat, 4 Aug 2012 15:01:04 -0400
> > > > >>>> "J. Bruce Fields" <bfields@xxxxxxxxxxxx> wrote:
> > > > >>>>
> > > > >>>>> On Fri, Aug 03, 2012 at 10:00:39PM -0400, Jeff Layton wrote:
> > > > >>>>>> On Fri, 3 Aug 2012 20:08:19 -0400
> > > > >>>>>> "J. Bruce Fields" <bfields@xxxxxxxxxxxx> wrote:
> > > > >>>>>>
> > > > >>>>>>> I'm getting
> > > > >>>>>>>
> > > > >>>>>>> # mount -tnfs -onfsvers=4 pip1:/exports /mnt/
> > > > >>>>>>>
> > > > >>>>>>> (OK, admittedly that's with 3.6.0-rc1 + a few experimental patches, but
> > > > >>>>>>> I doubt they're related.)
> > > > >>>>>>>
> > > > >>>>>>> Also:
> > > > >>>>>>>
> > > > >>>>>>> [root@pip2 ~]# modprobe nfs4
> > > > >>>>>>> [root@pip2 ~]# lsmod|grep nfs4
> > > > >>>>>>> [root@pip2 ~]#
> > > > >>>>>>>
> > > > >>>>>>> --b.
> > > > >>>>>>
> > > > >>>>>> I hit the same problem...
> > > > >>>>>>
> > > > >>>>>> Try removing /usr/lib/modprobe.d/nfs.conf (assuming you're running
> > > > >>>>>> Fedora).
> > > > >>>>>
> > > > >>>>> Oog, right.
> > > > >>>>>
> > > > >>>>> But, without testing--won't that make v4 mounts fail on older kernels?
> > > > >>>>
> > > > >>>> Actually, now that I look, this does not seem to break on older kernels
> > > > >>>> as long as you use a syntax like:
> > > > >>>>
> > > > >>>> # mount -t nfs server:/export /mnt/point -o vers=4
> > > > >>>>
> > > > >>>> ...if, however you use a syntax like:
> > > > >>>>
> > > > >>>> # mount -t nfs4 server:/export /mnt/point
> > > > >>>>
> > > > >>>> ...then it fails without the above file in place. I guess the question
> > > > >>>> we have to answer is: Do we want to continue to support the "-t nfs4"
> > > > >>>> mount syntax?
> > > > >>>
> > > > >>> I think you're right that we want to deprecate it.
> > > > >>>
> > > > >>> Though this is a bit of a harsh way to do it--would have been nice to
> > > > >>> have some transition period with a warning or something.
> > > > >>
> > > > >> I didn't expect this to be broken, both ways of mounting still work on my VMs so I expected them to work for everybody else too.
> > > > >
> > > > > Huh. Just checked on an old kernel without an "alias nfs4 nfs" in
> > > > > modprobe configuration, and sure enough I get "No such device".
> > > > >
> > > > > Maybe you have some initscripts or something else that's loading the
> > > > > nfs module for you before the mount?
> > > >
> > > > My nfs-common daemon script loads sunrpc, nfs
> > >
> > > Yep, that's why you're not seeing it.
> > >
> > > > and nfsd but not nfs2, nfs3 or nfs4.
> > > >
> > > > Could we rename the module to avoid the alias name collision? Something like this (untested) maybe?
> > >
> > > I don't think that will help.
> >
> > It should if we also add back in
> >
> > struct file_system_type nfs4_fs_type = {
> > .owner = THIS_MODULE,
> > .name = "nfs4",
> > .mount = nfs_fs_mount,
> > .kill_sb = nfs_kill_super,
> > .fs_flags = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
> > };
> >
> > and then add that to register_nfs_fs()/unregister_nfs_fs(). As far as I
> > can see, that will trigger all the right incantations in
> > nfs_validate_mount_data() to mount an NFSv4 filesystem.
> >
>
> So, move the nfs4 fstype definition back into nfs.ko? That would
> ensure that you could still do a "-t nfs4" mount with that modprobe
> alias in place.
No. I mean to add a separate nfs4_fstype definition in nfs.ko, and
register it so that the VFS recognises the 'nfs4' filesystem name.
> I think Bryan is correct though. We'll also need to rename nfs4.ko or
> you won't ever be able to call request_module for it in order to plug
> it in if you have that module alias in place.
You did note my use of the word "also" above?
> Does this mean that we plan to support the "-t nfs4" mount syntax in
> perpetuity?
No, but I also agree with Bruce's point that we shouldn't pull the plug
without some prior notice. We should at least keep an entry in
Documentation/feature-removal-schedule.txt for a few kernel revisions.
--
Trond Myklebust
Linux NFS client maintainer
NetApp
Trond.Myklebust@xxxxxxxxxx
www.netapp.com
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