Illumos #3949, #3950, #3952, #3953

3949 ztest fault injection should avoid resilvering devices
3950 ztest: deadman fires when we're doing a scan
3951 ztest hang when running dedup test
3952 ztest: ztest_reguid test and ztest_fault_inject don't place nice together
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Adam Leventhal <ahl@delphix.com>
Approved by: Richard Lowe <richlowe@richlowe.net>

References:
  https://www.illumos.org/issues/3949
  https://www.illumos.org/issues/3950
  https://www.illumos.org/issues/3951
  https://www.illumos.org/issues/3952
  illumos/illumos-gate@2c1e2b4414

Ported-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1775

Porting notes:

1. The deadman thread was removed from ztest during the original
   port because it depended on Solaris thr_create() interface.
   This functionality should be reintroduced using the more
   portable pthreads.

module/zfs/spa.c

@@ -752,6 +752,7 @@ spa_change_guid(spa_t *spa)
 	int error;
 	uint64_t guid;
 
+	mutex_enter(&spa->spa_vdev_top_lock);
 	mutex_enter(&spa_namespace_lock);
 	guid = spa_generate_guid(NULL);
 
@@ -764,6 +765,7 @@ spa_change_guid(spa_t *spa)
 	}
 
 	mutex_exit(&spa_namespace_lock);
+	mutex_exit(&spa->spa_vdev_top_lock);
 
 	return (error);
 }
@@ -4737,7 +4739,6 @@ spa_vdev_detach(spa_t *spa, uint64_t guid, uint64_t pguid, int replace_done)
 		if (pvd->vdev_ops == &vdev_spare_ops)
 			cvd->vdev_unspare = B_FALSE;
 		vdev_remove_parent(cvd);
-		cvd->vdev_resilvering = B_FALSE;
 	}
 
 
@@ -5369,6 +5370,13 @@ spa_vdev_resilver_done_hunt(vdev_t *vd)
 			return (oldvd);
 	}
 
+	if (vd->vdev_resilvering && vdev_dtl_empty(vd, DTL_MISSING) &&
+	    vdev_dtl_empty(vd, DTL_OUTAGE)) {
+		ASSERT(vd->vdev_ops->vdev_op_leaf);
+		vd->vdev_resilvering = B_FALSE;
+		vdev_config_dirty(vd->vdev_top);
+	}
+
 	/*
 	 * Check for a completed replacement.  We always consider the first
 	 * vdev in the list to be the oldest vdev, and the last one to be

module/zfs/vdev_file.c

@@ -162,7 +162,6 @@ vdev_file_io_strategy(void *arg)
 static int
 vdev_file_io_start(zio_t *zio)
 {
-	spa_t *spa = zio->io_spa;
 	vdev_t *vd = zio->io_vd;
 	vdev_file_t *vf = vd->vdev_tsd;
 
@@ -185,8 +184,8 @@ vdev_file_io_start(zio_t *zio)
 		return (ZIO_PIPELINE_CONTINUE);
 	}
 
-	spa_taskq_dispatch_ent(spa, ZIO_TYPE_FREE, ZIO_TASKQ_ISSUE,
-	    vdev_file_io_strategy, zio, 0, &zio->io_tqent);
+	VERIFY3U(taskq_dispatch(system_taskq, vdev_file_io_strategy, zio,
+	    TQ_SLEEP), !=, 0);
 
 	return (ZIO_PIPELINE_STOP);
 }