On Sat, Dec 24, 2016 at 10:48:29AM +0100, Xen wrote: > Hi, > > On a Debian server I have mounted several snapshots daily that I > export with NFS. > > At the end of the day the nfs-kernel-server service is shut down, > the snapshots are renewed, remounted, and the server is brought > online again. > > In the beginning (I haven't been doing this for long) it all worked > fine and I could mount the shares on the client, which is an older > NAS unit, running an old kernel as 2.6.32. > > Yet one of the shares now refuses to get mounted and I don't know > why. The only thing I haven't tried is actually renaming the mount > points. > > mount: mounting island.vpn:/srv/root on /mnt/remote/root failed: > Stale NFS file handle > > This "island.vpn" simply translates to 10.8.20.25, in this case. > > This is one of 5 mounts and one of 5 snapshots. The other snapshots > simply succeed. > > I have rebooted both servers. > > I have removed the mount points on both places: the mount points for > the snapshots, and the mount points for the shares on the client. > > I have run exportfs -r and exportfs -f. > > Oh, apologies, I see the issue, or at least part of it. > > Dec 24 02:45:35 island rpc.mountd[3217]: / and /srv/root have same > filehandle for diskstation.vpn, using first Huh. That message is from utils/mountd/cache.c:nfsd_fh(). > I really wanted to find out if it uses nfs3 or nfs4, but I think it > uses nfs 4. > > The above message does not always repeat itself: > > Dec 24 02:56:35 island rpc.mountd[3217]: authenticated mount request > from 10.8.20.1:944 for /srv/root (/srv/root) > Dec 24 02:58:09 island rpc.mountd[3217]: authenticated mount request > from 10.8.20.1:638 for /srv/boot (/srv/boot) > > The site uses LVM snapshots, root (and boot) are regular, non-thin > snapshots. > > These are my exports: > > /srv/home diskstation(ro,no_subtree_check,no_root_squash) > /srv/data diskstation(ro,no_subtree_check,no_root_squash) > /srv/sites diskstation(ro,no_subtree_check,no_root_squash) > /srv/boot diskstation(ro,no_subtree_check,no_root_squash) > /srv/root diskstation(ro,no_subtree_check,no_root_squash) > > All other mounts succeed without issue. Root did fine at first as well. > > Edit: adding fsid=22 to the root line fixed it: > > /srv/home diskstation(ro,no_subtree_check,no_root_squash) > /srv/data diskstation(ro,no_subtree_check,no_root_squash) > /srv/sites diskstation(ro,no_subtree_check,no_root_squash) > /srv/boot diskstation(ro,no_subtree_check,no_root_squash) > /srv/root diskstation(ro,fsid=22,no_subtree_check,no_root_squash) > > All snapshots are independently mounted and hence do not contain > other mounts on them. > > Well I'm glad that's sorted. I don't know why the NFS server would > pick a filesystem to export that wasn't even mentioned. Of course > the snapshot and the root (original) will have the same UUID. At a guess, this may be the v4 pseudoroot code: it exports (under heavy restrictions) all the directories required to reach any exported filesystem. So maybe mountd, when searching for a filesystem matching the given filehandle, found that pseudoroot export for "/", then later found the real export for "/srv/root", and resolved the conflict by sticking with the first one. We could tell mountd to resolve such conflicts in favor of non-pseudroot filesystems. I'm not sure that would work. Is there some way we could make sure a new uuid is generated for the snapshots, so we avoid this kind of conflict even when explicitly exporting multiple snapshots of the same filesystem? Requiring admins to add explicit fsid='s all over seems unhelpful. --b. > Not its partition, but its filesystem will. > > So I apologize for this message ;-). > > Regards. > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
