If the receive or rollback is performed while filesystem is upgrading
the objset may be evicted in `dsl_dataset_clone_swap_sync_impl`. This
will lead to NULL pointer dereference when upgrade tries to access
evicted objset.
This commit adds long hold of dataset during whole upgrade process.
The receive and rollback will return an EBUSY error until the
upgrade is not finished.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Arkadiusz Bubała <arkadiusz.bubala@open-e.com>
Closes#5295Closes#6837
c0daec32f8