On January 23, 2010 6:53:26 PM -0600 Bob Friesenhahn
<bfrie...@simple.dallas.tx.us> wrote:
On Sat, 23 Jan 2010, Frank Cusack wrote:
Notice that the referenced path is subordinate to the exported zfs
filesystem.
Well, assuming there is a single home zfs filesystem and not a
filesystem-per-user. For filesystem-per-user your example simply
mounts the correct shared filesystem. Even for a single home
filesystem, the above doesn't actually mount /export/home and
then also mount /export/home/USER, so it's not following the
zfs filesystem hierarchy.
I am using a filesystem-per-user on my system. Are you saying that my
system is wrong?
These per-user fileystems are NFS exported due to the inheritance of zfs
properties from their parent directory. The property is only set in one
place.
You have misunderstood the problem.
Of course, or rather I understand, that zfs child filesystems inherit
the sharenfs property from the parent similar to how they inherit other
properties. (And even if they didn't, clients can still mount
subdirectories of the directory that is shared unless the server
explicitly disallows that option. Regardless of underlying filesystem.)
With zfs filesystems, when you have a directory which is a subordinate
filesystem, as in filesystem-per-user, then if the NFS client mounts the
parent filesystem, when it crosses the child filesystem boundary it does
not see into the child filesystem as it would if it were local.
server:
export
export/home
export/home/user
client mounts server:/export/home on /home. the client can see (e.g.)
/home/user, but as an empty directory. when the client enters that
directory it is writing into the export/home filesystem on the server
(and BTW those writes are not visible on the server since they are
obscured by the child filesystem.)
NFS4 has a mechanism to follow and mount the child filesystem.
Your example doesn't do that, it simply mounts the child filesystem
directly.
-frank
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