Previously a tqent could be recycled prematurely, update the
code to use a hash table for lookups to resolve this.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@ixsystems.com>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Closes#10529
3933305eac