illumos/illumos-gate@1a01181fdc1a01181fdchttps://www.illumos.org/issues/7580
We need to prevent any reader whenever we're about the zero out all the
blkptrs. To do this we need to grab the dn_struct_rwlock as writer in
dbuf_write_children_ready and free_children just prior to calling bzero.
Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed by: Steve Gonczi <steve.gonczi@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Approved by: Dan McDonald <danmcd@omniti.com>
Author: George Wilson <george.wilson@delphix.com>
2bfa921051