SOLVED: NFS share mounted rw OK, Permission denied writing

grunthus · Last edited by grunthus on Sat Feb 21, 2009 3:35 pm; edited 1 time in total

Hi,

I have 12 gentoo boxes on a LAN using /home mounted via NFS. 1 of the boxes is being a right pain in the derriere. All other 11 boxes mount rw and allow rw in practice. One client (fladdicap) reports mount as rw but in practice behaves as read only, giving Permission Denied on any write attempt.

The client mounting via NFS with a problem is hostname fladdicap.
The NFS server is hostname mooa.

Client fladdicap's fstab line:

shickapooka800 · Guru Joined: 05 Dec 2004 Posts: 304 Location: no

when you ls -al the directories on the client, do they have the same permissions as on other clients and the server?

just as a sanity check, you could make an empty test directory and experiment with different permissions (777, 755, 775 etc...) and mount it on the troubled client. this will make sure that nfs is working properly.

if all goes well, maybe it is a userid,groupid mangleing problem? how are users and groups managed across these machines? how are the userid's and groupid's different on the troubled machine?

krinn · Watchman Joined: 02 May 2003 Posts: 7470

also try <ls /var/lib/nfs/rpc_pipefs> on client computer that doesn't work

Hu · Administrator Joined: 06 Mar 2007 Posts: 23088

You would get Read-only file system if it was a read-only mount. Either you have a userid mapping problem or, if you are using root, you have root squashing turned on and root on the client is being mapped to nobody on the server. Thus, root can only write to a file if nobody can write to that file.

grunthus · Posted: Tue Nov 25, 2008 3:28 pm Post subject:

Hu · Administrator Joined: 06 Mar 2007 Posts: 23088

Yes, that sounds like a uid mapping problem. What is the output of id bob on the server and the output of id in the shell that tried to touch a file in /home/test?

Also, note that root squashing is enabled by default, and your exports line does not disable it.

sleepless9 · n00b Joined: 27 Aug 2008 Posts: 5

I had the same problem a few weeks ago.. Mounting ok, listing files ok, but permission denied on writing. And the day before that everything worked fine.
I spent a day to double-check my configuration and the UIDs again, just to find out in the end that I had different versions of nfs-utils (and/or) portmap between the server and the client.. Probably an upgrade screwed something up. Emerging the latest version of portmap and nfs-utils in both machines solved it for me. Remember to shut portmap down before emerging. After the update I remember getting strange errors while trying to mount, and the problem was an rpc.statd running from the previous version that was not killed from init.d.

grunthus · Posted: Sat Feb 21, 2009 3:34 pm Post subject:

Since I don't want to tinker with my NFS server just yet I just downgraded my client boxes net-fs/nfs-utils to version 1.1.0-r1 (upgrade to 1.1.3 seemed to break rw access to mounted filesystems over NFS)

(I'm building a replacement NFS/ypbind server for one which has not been upgraded for several years, 2.4 kernel, Pentium2 350MHz - so I'm just not going near upgrading it. Strange how one develops a sense of attachment to a venerable old box, which has served my network for years 24/7 with no complaints)
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rfabbri · n00b Joined: 02 Apr 2009 Posts: 2