Most recent kernel where this bug did *NOT* occur: 2.6.18.2 Distribution: Debian Sarge Hardware Environment: Amd Atholon Software Environment: Debian Sarge mount 2.4.2 Problem Description: I have diskless linux client and on server I have exported this direcories 1)/var/lib/diskless/default/root 192.168.3.0/255.255.255.0(ro,async) 2)/var/lib/diskless/default/192.168.3.48 192.168.3.48(rw,no_root_squash,async) When clien boots it mounts as root 1) and it is read only. After this mount 2) as /etc/ /tmp/ /dev and /var over this and this directories are normaly read-wite. But with 2.6.19 direcories are default mounted ro and if I eg. do mount /tmp -o remount,rw now /etc/ /dev/ /tmp/ /var are mounted rw !!!. Steps to reproduce: Server which exports have kenrnel 2.6.18.2 and client 2.6.19
The VFS does not, and has not ever, allowed you to remount the same filesystem with different mount options. NFS 'allowed' this because if you mounted a different directory, it would treat that as a different filesystem. Unfortunately, that leads to nasty cache consistency problems. As of 2.6.19, NFS will group all directories that belong to the same filesystem on the server into the same superblock and hence treat them as the same filesystem on the client.
Thanks for explanation, but problem is in another place :-) I compile kenrnel with NFSv3 and NFSv4 support ana problem disapear na client boots. Thanks again.