illumos/illumos-gate@09c9e6dc9b09c9e6dc9bhttps://www.illumos.org/issues/7542
libshare keeps a cached copy of the sharetab listing in memory, which can
become out of date if shares are destroyed or created while leaving a libzfs
handle open. This results in a spurious unmounting failure when an NFS share
exists but isn't in the stale libshare cache.
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Dan Kimmel <dan.kimmel@delphix.com>
Reviewed by: Matt Amdur <matt.amdur@delphix.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Author: Chris Williamson <chris.williamson@delphix.com>
910a9fff3b