Wednesday, October 18, 2006

NFS issue

After some delay I'm back again. I've compiled and installed a new (2.6.19-rc2) kernel. After reboot it works correctly. Almost. One exception occured, nfs remote mounted filesystem with home dirs is still mounting read only even if it is tell to mount it read-write.

I tried to find out the reason and with some help from nfs folks I investigated, that homes and user directories are mounted from same disk partition with one substantial difference: there is a read-only protection of exported /usr and true rw access for /home dirs.

The new code sets first mount options even to the second, third etc. mountpoint if they are on the same disk part on the server. The caveat is, that this is visible only in /proc/mounts, not in /etc/mtab (what mount outputs).

This disk partition is ugly for this purpose, because subtree checking has to be enabled due to security (otherwise anybody has access to mentioned /usr part), but it's not so good option for so much changing files, which surely are in home directories.

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