MFC r224814, r224855:

MFC r224814, r224855:

MFC r224814 [1]:
Fix race between dmu_objset_prefetch() invoked from
zfs_ioc_dataset_list_next() and dsl_dir_destroy_check() indirectly
invoked from dmu_recv_existing_end() via dsl_dataset_destroy() by not
prefetching temporary clones, as these count as always inconsistent.
In addition, do not prefetch hidden datasets at all as we are not
going to process these later.

Filed as Illumos Bug #1346

MFC r224855:
zfs_ioctl.c: improve code readability in zfs_ioc_dataset_list_next()

zvol.c: fix calling of dmu_objset_prefetch() in zvol_create_minors()
by passing full instead of relative dataset name and prefetching all
visible datasets to be processed later instead of just the pool name

PR:		kern/157728 [1]
Tested by:	Borja Marcos <borjam@sarenet.es> [1], mm
Reviewed by:	pjd

git-svn-id: svn://svn.freebsd.org/base/stable/8@225022 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f