Bug 968023

Wow, so this one confused me for a while.

So I think it works like this. "mount.nfs", if you call it with no nfsvers= option, will first try an NFSv4 mount, and then fall back to doing an NFSv3 mount if that fails. If you try to configure an NFS repo - either by passing inst.repo=nfs:foo (so long as there's also an inst.root or inst.stage2 parameter and 811242 doesn't come into play) or by using the Installation Source spoke - anaconda will just go ahead and call out to 'mount.nfs' , so it ought to get this behaviour, and people's NFS repos ought to work whether they're v3 or v4.

However, it looks like NFSv3 mounts don't actually work unless rpc.statd is running or the 'nolock' option is passed.

To reproduce - I set up an NFS server capable of both NFSv3 and NFSv4, containing a Fedora ISO in the directory /export/fedora , and with this /etc/exports:

/export 192.168.1.0/24(ro,sync,insecure,root_squash,no_subtree_check,fsid=0)
/export/fedora 192.168.1.0/24(rw,nohide,sync,insecure,root_squash,no_subtree_check)

Now, if I pass 'inst.repo=nfs:192.168.1.105:/fedora' - which will succeed as an NFSv4 mount - or enter '192.168.1.105:/fedora' as an NFS repo on Installation Destination, it works fine.

If I pass 'inst.repo=nfs:192.168.1.105:/export/fedora' - which would succeed only as an NFSv3 mount - it should try to mount that as NFSv4, fail, and fall back to mounting it as NFSv3. Indeed, it actually tries to. However, it fails, and I get this output in program.log:

19:23:03,215 INFO program: Running... mount -t nfs -o  192.168.1.105:/export/fedora /mnt/install/source
19:23:03,418 INFO program: mount.nfs: rpc.statd is not running but is required for remote locking.
19:23:03,419 INFO program: mount.nfs: Either use '-o nolock' to keep locks local, or start statd.
19:23:03,419 INFO program: mount.nfs: mounting 192.168.1.105:/export/fedora failed, reason given by server: No such file or directory

Now that stuff about statd and nolock is apparently important. Because if I pass 'inst.repo=nfs:nolock:192.168.1.105:/export/fedora' - note, I have still not specified an NFS protocol version explicitly, but I have passed 'nolock' - it works! The mount succeeds (with no output but a 0 return code) and the repo is happily accepted by anaconda. So it seems like mount.nfs' mechanism for v4->v3 fallback is working fine, but by not starting rpc.statd or using the 'nolock' option for NFS mounts, anaconda is not allowing v3 mounts to work without the user doing it instead.

So, can we do something here? Start rpc.statd if an NFS repo is being configured? Pass in 'nolock' for NFS mounts? Or are both of those a problem somehow and we should document the use of 'nolock' manually for NFSv3 repos? Thanks!

Setting severity 'high' as this behaviour is extremely non-obvious and could cause considerable frustration for users with NFSv3-only mounts.