NFS4 does (not) mount locally depending on multiple entries in /etc/exports

LeFrnk · 09-19-2018, 11:10 AM

I have a /etc/exports on a machine 192.168.122.1 like this:

Code:

/mnt/platte 192.168.122.0/24(rw,sync,no_root_squash,no_subtree_check,fsid=0) 127.0.0.1(rw,sync,no_root_squash,no_subtree_check)

So, from client 192.168.122.2 I can mount the 192.168.122.1:/ share. Works. (See / cause of fsid=0)

But locally, on the nfs server machine 192.168.122.1 I cannot mount 127.0.0.1:/mnt/platte

Code:

# mount -t nfs4 127.0.0.1:/mnt/platte /mnt/test
mount.nfs4: mounting 127.0.0.1:/mnt/platte failed, reason given by server: No such file or directory

(Of course 127.0.0.1:/ doesn't mount either, but that's desired behavior.)

Then, when I edit /etc/exports removing the remote export like this:

Code:

/mnt/platte 127.0.0.1(rw,sync,no_root_squash,no_subtree_check)

Then I do a restart of nfs process.
Now I can locally mount the 127.0.0.1:/ share. Why that? Isn't that strange?!

showmount -e always shows the expected correct stuff.

MensaWater · 09-19-2018, 02:27 PM

So the first question is why are you trying to make it a local NFS4 mount to the exporting server rather than simply creating a symbolic link to the local filesystem? e.g.
ln -s /mnt/platte /mnt/test

Alternatively you could do a loop back mount locally.

Assuming you have a reason to use an NFS4 mount rather than a symbolic link on the export server, 192.168.122.1, why bother with 127.0.0.1 if you've exported with the IP 192.168.122.1. You could mount on client 192.168.122.1 from server 192.168.122.1 just as you did on client 192.168.122.2 from server 192.168.122.1.

LeFrnk · 09-19-2018, 04:12 PM

Thanks. Mounting via public IP does work locally, indeed.

Why I do this:
I somehow wanted to make sure there are no conflicts, when I am changing files in a shared directory from remote and locally at the same time.
My hope was, if all changes go through NFS4, the NFS server takes care of that.
I was afraid that changing files under NFS's ass would perhaps result in conflicts.
Can that be ruled out?

MensaWater · 09-21-2018, 01:56 PM

File locking in NFS4 is not as robust as you suggest so I don't think you'll get benefit using NFS4 locally over symbolic links.

You might want to read through this thread.