nfs subvolume access?

Ulli Horlacher
2021-03-10T07:55:35Z

When I try to access a btrfs filesystem via nfs, I get the error:

root@tsmsrvi:~# mount tsmsrvj:/data/fex /nfs/tsmsrvj/fex
root@tsmsrvi:~# time find /nfs/tsmsrvj/fex | wc -l
find: File system loop detected; '/nfs/tsmsrvj/fex/spool' is part of the same file system loop as '/nfs/tsmsrvj/fex'.
1
root@tsmsrvi:~#

On tsmsrvj I have in /etc/exports:

/data/fex tsmsrvi(rw,async,no_subtree_check,no_root_squash)

This is a btrfs subvolume with snapshots:

root@tsmsrvj:~# btrfs subvolume list /data
ID 257 gen 35 top level 5 path fex
ID 270 gen 36 top level 257 path fex/spool
ID 271 gen 21 top level 270 path fex/spool/.snapshot/2021-03-07_1453.test
ID 272 gen 23 top level 270 path fex/spool/.snapshot/2021-03-07_1531.test
ID 273 gen 25 top level 270 path fex/spool/.snapshot/2021-03-07_1532.test
ID 274 gen 27 top level 270 path fex/spool/.snapshot/2021-03-07_1718.test

root@tsmsrvj:~# find /data/fex | wc -l
489887
root@tsmsrvj:~#

What must I add to /etc/exports to enable subvolume access for the nfs
client?

tsmsrvi and tsmsrvj (nfs client and server) both run Ubuntu 20.04 with
btrfs-progs v5.4.1

--
Ullrich Horlacher Server und Virtualisierung
Rechenzentrum TIK
Universitaet Stuttgart E-Mail: horlacher@tik.uni-stuttgart.de
Allmandring 30a Tel: ++49-711-68565868
70569 Stuttgart (Germany) WWW: http://www.tik.uni-stuttgart.de/
REF:<20210310074620.GA2158@tik.uni-stuttgart.de>