Mounting nested ZFS filesystems exported via NFS

Question

I have a linux (ubuntu) server with a zfs pool containing nested fileystem. E.g.:

zfs_pool/root_fs/fs1
zfs_pool/root_fs/fs2
zfs_pool/root_fs/fs3

I have enabled NFS sharing on the root filesystem (via zfs, not by editing /etc/exports). Nested filesystems inherit this property.

NAME              PROPERTY  VALUE                                SOURCE
zfs_pool/root_fs  sharenfs  rw=192.168.1.0/24,root_squash,async  local

NAME                  PROPERTY  VALUE                                SOURCE
zfs_pool/root_fs/fs1  sharenfs  rw=192.168.1.0/24,root_squash,async  inherited from zfs_pool/root_fs

On the client machines (linux, mostly ubuntu), the only filesystem I explicitly mount is the root filesystem.

mount -t nfs zfsserver:/zfs_pool/root_fs /root_fs_mountpoint

Nested filesystems are mounted automatically when they are accessed. I didn't need to configure anything to make this work.

This is great, but I'd like to know who is providing this feature. Is it ZFS? Is it NFS? Is it something else on the client side (something like autofs, which isn't even installed).

I'd like to change the timeout after which nested filesystems are unmounted, but I don't even know which configuration to edit and which documentation to read.

Answer 1

ZFS is using kernel NFS. If you want to make changes to the NFS server option, you can use zfs set command. If you want to make changes to NFS client option, you can make changes with -o.