mount ZFS snapshot on Linux system

[Jason Keltz]

I'm running FreeBSD 9.2 with various ZFS datasets.
I export a dataset to a Linux system (RHEL64), and mount it.  It works 
fine...
When I try to access the ZFS snapshot directory on the Linux NFS client, 
things go weird.

With NFSv4:

[jas at archive /]# cd /mnt/.zfs/snapshot
[jas at archive snapshot]# ls
20131203  20131205  20131206  20131207  20131208  20131209  20131210
[jas at archive snapshot]# cd 20131210
20131210: Not a directory.

huh?

[jas at archive snapshot]# ls -al
total 77
dr-xr-xr-x   9 root root   9 Dec 10 11:20 .
dr-xr-xr-x   4 root root   4 Nov 28 15:42 ..
drwxr-xr-x 380 root root 380 Dec  2 15:56 20131203
drwxr-xr-x 381 root root 381 Dec  3 11:24 20131205
drwxr-xr-x 381 root root 381 Dec  3 11:24 20131206
drwxr-xr-x 381 root root 381 Dec  3 11:24 20131207
drwxr-xr-x 381 root root 381 Dec  3 11:24 20131208
drwxr-xr-x 381 root root 381 Dec  3 11:24 20131209
drwxr-xr-x 381 root root 381 Dec  3 11:24 20131210
[jas at archive snapshot]# stat *
[jas at archive snapshot]# ls -al
total 292
dr-xr-xr-x 9 root      root         9 Dec 10 11:20 .
dr-xr-xr-x 4 root      root         4 Nov 28 15:42 ..
-rw-r--r-- 1 uax    guest   137647 Mar 17  2010 20131203
-rw-r--r-- 1 uax    guest         865 Jul 31  2009 20131205
-rw-r--r-- 1 uax    guest   137647 Mar 17  2010 20131206
-rw-r--r-- 1 uax    guest         771 Jul 31  2009 20131207
-rw-r--r-- 1 uax    guest         778 Jul 31  2009 20131208
-rw-r--r-- 1 uax     guest       5281 Jul 31  2009 20131209
-rw------- 1 btx      faculty      893 Jul 13 20:21 20131210

But it gets even more fun..

# ls -ali
total 205
   2 dr-xr-xr-x   9 root      root       9 Dec 10 11:20 .
   1 dr-xr-xr-x   4 root      root       4 Nov 28 15:42 ..
863 -rw-r--r--   1 uax     guest 137647 Mar 17  2010 20131203
   4 drwxr-xr-x 381 root      root     381 Dec  3 11:24 20131205
   4 drwxr-xr-x 381 root      root     381 Dec  3 11:24 20131206
   4 drwxr-xr-x 381 root      root     381 Dec  3 11:24 20131207
   4 drwxr-xr-x 381 root      root     381 Dec  3 11:24 20131208
   4 drwxr-xr-x 381 root      root     381 Dec  3 11:24 20131209
   4 drwxr-xr-x 381 root      root     381 Dec  3 11:24 20131210

This is not a user id mapping issue because all the files in /mnt have 
the proper owner/groups, and I can access them there fine.

I also tried explicitly exporting .zfs/snapshot.  The result isn't any 
different.

If I use nfs v3 it "works", but I'm seeing a whole lot of errors like 
these in syslog:

Dec 10 12:32:28 jungle mountd[49579]: can't delete exports for 
/local/backup/home9/.zfs/snapshot/20131203: Invalid argument
Dec 10 12:32:28 jungle mountd[49579]: can't delete exports for 
/local/backup/home9/.zfs/snapshot/20131209: Invalid argument
Dec 10 12:32:28 jungle mountd[49579]: can't delete exports for 
/local/backup/home9/.zfs/snapshot/20131210: Invalid argument
Dec 10 12:32:28 jungle mountd[49579]: can't delete exports for 
/local/backup/home9/.zfs/snapshot/20131207: Invalid argument

It's not clear to me why this doesn't just "work".

Can anyone provide any advice on debugging this?

Thanks,

Jason.

-- 
Jason Keltz
Manager of Development
Department of Electrical Engineering and Computer Science
York University, Toronto, Canada
Tel: 416-736-2100 x. 33570
Fax: 416-736-5872