remount error: 'unknown nfs mount option: v3'

remount error: 'unknown nfs mount option: v3'

[Nitin Chandrachoodan]

Hello,

We have a diskless client setup in our lab, with / and /usr
mounted from a server. The server is running a standard RedHat
8.0 distrib, and the clients have a standard (except for
recompiled kernel) RedHat 9.0. nfs-utils, mount etc. are the
standard versions out of the box.

The /etc/exports on the server contains

/tftpboot           192.168.15.0/24(rw,sync,no_root_squash)
/home1/remoteusr    192.168.15.0/24(rw,sync,no_root_squash)

The root fs is mounted by the kernel option to pxelinux given by 
  DEFAULT linux
  LABEL   linux
          KERNEL bzImage.wks
          APPEND panic=5 nfsroot=192.168.15.1:/tftpboot
          IPAPPEND 1

The /usr is mounted in rc.sysinit using 
action $"Mounting /usr partition" mount 192.168.15.1:/home1/remoteusr /usr -t nfs -o ro,nolock

So far so good, it boots up, and runs normally. 

The problem arises when I try to remount the / and /usr as
read-write (to install software on the client). When I try 
  mount -n -o remount,rw /
  mount -n -o remount,rw /usr

the second mount fails with "unknown nfs mount option: v3".

I noticed that typing 'mount' after bootup shows
  /dev/root on / type nfs (ro,v2,rsize=4096,wsize=4096,hard,udp,nolock,addr=192.168.15.1)
  192.168.15.1:/home1/remoteusr on /usr type nfs (ro,v3,rsize=4096,wsize=4096,hard,udp,nolock,addr=192.168.15.1)

The /etc/fstab does not contain any of the entries, and
/etc/mtab is linked to /proc/mounts.

It seems that the 'v3' showing up in the mount listing is
causing the problem. I dont know why it is there, and why the /
got mounted as v2, I did not specify those options anywhere.

How are default options passed to the NFS systems? Are they
compiled into the kernel? When I try mounting these same
filesystems from another RH9 machine that is not diskless, it
works fine, and mount shows 
  nfs:/home1/remoteusr on /mnt/hdd type nfs (rw,addr=192.168.15.1)

Any suggestions would be greatly appreciated.

Thanks in advance,

Nitin


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Re: remount error: 'unknown nfs mount option: v3'

[Chip Salzenberg]

According to Nitin Chandrachoodan:
>   mount -n -o remount,rw /
>   mount -n -o remount,rw /usr
> 
> the second mount fails with "unknown nfs mount option: v3".
> 
> /etc/mtab is linked to /proc/mounts.

That's not really a supported configuration, AFAIK.  While /etc/mtab
and /proc/mounts are obviously similar, they're not identical, and
you've run into one of the results.

That said, I really can't fathom why mount wants "vers=3" but refuses
to accept "v3", while the kernel only reports "v3".  It seems like a
pointless inconsistency.  Why not have mount accept "v2", "v3", and
"v4" as synoyms for the corresponding "vers=" values?
-- 
Chip Salzenberg               - a.k.a. -               <chip@pobox.com>
"I wanted to play hopscotch with the impenetrable mystery of existence,
    but he stepped in a wormhole and had to go in early."  // MST3K


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Re: Re: remount error: 'unknown nfs mount option: v3'

[Trond Myklebust]

>>>>> " " == Chip Salzenberg <chip@pobox.com> writes:

     > refuses to accept "v3", while the kernel only reports "v3".  It
     > seems like a pointless inconsistency.  Why not have mount
     > accept "v2", "v3", and "v4" as synoyms for the corresponding
     > "vers=" values?

Feel free...

Note however that vers=4 is unlikely ever to be supported. The entire
mount interface is so different from v2/v4 that I prefer to keep NFSv4
as a completely separate filesystem (i.e. 'mount -t nfs4').

Cheers,
  Trond


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