zed: Prevent special vdev to be replaced by hot spare

Special vdevs should not be replaced by a hot spare.
Log vdevs already support this, extending the
functionality for special vdevs.

Signed-off-by: Ameer Hamza <ahamza@ixsystems.com>

module/zfs/spa.c

@@ -6819,10 +6819,12 @@ spa_vdev_attach(spa_t *spa, uint64_t guid, nvlist_t *nvroot, int replacing,
 		return (spa_vdev_exit(spa, newrootvd, txg, error));
 
 	/*
-	 * Spares can't replace logs
+	 * log, dedup and special vdevs should not be replaced by spares.
 	 */
-	if (oldvd->vdev_top->vdev_islog && newvd->vdev_isspare)
+	if ((oldvd->vdev_top->vdev_alloc_bias != VDEV_BIAS_NONE ||
+	    oldvd->vdev_top->vdev_islog) && newvd->vdev_isspare) {
 		return (spa_vdev_exit(spa, newrootvd, txg, ENOTSUP));
+	}
 
 	/*
 	 * A dRAID spare can only replace a child of its parent dRAID vdev.