Commit 4c5b89f59 refactored dnode_hold() and in the process
accidentally introduced a slight change in behavior which was
not intended. The required behavior is that once the ZPL,
or other consumer, declares its intent to free a dnode then
dnode_hold() should immediately start failing. This updated
code wouldn't return the failure until after it was freed.
When DNODE_MUST_BE_ALLOCATED is set it must return ENOENT, and
when DNODE_MUST_BE_FREE is set it must return EEXIST;
This issue was uncovered by ztest_remap() which attempted
to remap a freeing object which should have been skipped as
described by the comment in dmu_objset_remap_indirects_impl().
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Tom Caputi <tcaputi@datto.com>
Reviewed-by: Olaf Faaland <faaland1@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#8172
78e2139467
