3956 ::vdev -r should work with pipelines
3957 ztest should update the cachefile before killing itself
3958 multiple scans can lead to partial resilvering
3959 ddt entries are not always resilvered
3960 dsl_scan can skip over dedup-ed blocks if physical birth != logical birth
3961 freed gang blocks are not resilvered and can cause pool to suspend
3962 ztest should print out zfs debug buffer before exiting
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Adam Leventhal <ahl@delphix.com>

*** 192,201 ****
--- 192,202 ----
          scn->scn_phys.scn_ddt_class_max = DDT_CLASSES - 1; /* the entire DDT */
          scn->scn_phys.scn_start_time = gethrestime_sec();
          scn->scn_phys.scn_errors = 0;
          scn->scn_phys.scn_to_examine = spa->spa_root_vdev->vdev_stat.vs_alloc;
          scn->scn_restart_txg = 0;
+         scn->scn_done_txg = 0;
          spa_scan_stat_init(spa);
  
          if (DSL_SCAN_IS_SCRUB_RESILVER(scn)) {
                  scn->scn_phys.scn_ddt_class_max = zfs_scrub_ddt_class_max;
  
*** 767,777 ****
           * are doing this on behalf of a deleted snapshot, and we will
           * revisit the future block on the next pass of this dataset.
           * Don't scan it now unless we need to because something
           * under it was modified.
           */
!         if (bp->blk_birth <= scn->scn_phys.scn_cur_max_txg) {
                  scan_funcs[scn->scn_phys.scn_func](dp, bp, zb);
          }
          if (buf)
                  (void) arc_buf_remove_ref(buf, &buf);
  }
--- 768,778 ----
           * are doing this on behalf of a deleted snapshot, and we will
           * revisit the future block on the next pass of this dataset.
           * Don't scan it now unless we need to because something
           * under it was modified.
           */
!         if (BP_PHYSICAL_BIRTH(bp) <= scn->scn_phys.scn_cur_max_txg) {
                  scan_funcs[scn->scn_phys.scn_func](dp, bp, zb);
          }
          if (buf)
                  (void) arc_buf_remove_ref(buf, &buf);
  }
*** 1212,1222 ****
          if (scn->scn_phys.scn_state != DSS_SCANNING)
                  return;
  
          for (int p = 0; p < DDT_PHYS_TYPES; p++, ddp++) {
                  if (ddp->ddp_phys_birth == 0 ||
!                     ddp->ddp_phys_birth > scn->scn_phys.scn_cur_max_txg)
                          continue;
                  ddt_bp_create(checksum, ddk, ddp, &bp);
  
                  scn->scn_visited_this_txg++;
                  scan_funcs[scn->scn_phys.scn_func](scn->scn_dp, &bp, &zb);
--- 1213,1223 ----
          if (scn->scn_phys.scn_state != DSS_SCANNING)
                  return;
  
          for (int p = 0; p < DDT_PHYS_TYPES; p++, ddp++) {
                  if (ddp->ddp_phys_birth == 0 ||
!                     ddp->ddp_phys_birth > scn->scn_phys.scn_max_txg)
                          continue;
                  ddt_bp_create(checksum, ddk, ddp, &bp);
  
                  scn->scn_visited_this_txg++;
                  scan_funcs[scn->scn_phys.scn_func](scn->scn_dp, &bp, &zb);
*** 1455,1464 ****
--- 1456,1475 ----
          }
  
          if (scn->scn_phys.scn_state != DSS_SCANNING)
                  return;
  
+         if (scn->scn_done_txg == tx->tx_txg) {
+                 ASSERT(!scn->scn_pausing);
+                 /* finished with scan. */
+                 zfs_dbgmsg("txg %llu scan complete", tx->tx_txg);
+                 dsl_scan_done(scn, B_TRUE, tx);
+                 ASSERT3U(spa->spa_scrub_inflight, ==, 0);
+                 dsl_scan_sync_state(scn, tx);
+                 return;
+         }
+ 
          if (scn->scn_phys.scn_ddt_bookmark.ddb_class <=
              scn->scn_phys.scn_ddt_class_max) {
                  zfs_dbgmsg("doing scan sync txg %llu; "
                      "ddt bm=%llu/%llu/%llu/%llx",
                      (longlong_t)tx->tx_txg,
*** 1490,1502 ****
          zfs_dbgmsg("visited %llu blocks in %llums",
              (longlong_t)scn->scn_visited_this_txg,
              (longlong_t)NSEC2MSEC(gethrtime() - scn->scn_sync_start_time));
  
          if (!scn->scn_pausing) {
!                 /* finished with scan. */
!                 zfs_dbgmsg("finished scan txg %llu", (longlong_t)tx->tx_txg);
!                 dsl_scan_done(scn, B_TRUE, tx);
          }
  
          if (DSL_SCAN_IS_SCRUB_RESILVER(scn)) {
                  mutex_enter(&spa->spa_scrub_lock);
                  while (spa->spa_scrub_inflight > 0) {
--- 1501,1513 ----
          zfs_dbgmsg("visited %llu blocks in %llums",
              (longlong_t)scn->scn_visited_this_txg,
              (longlong_t)NSEC2MSEC(gethrtime() - scn->scn_sync_start_time));
  
          if (!scn->scn_pausing) {
!                 scn->scn_done_txg = tx->tx_txg + 1;
!                 zfs_dbgmsg("txg %llu traversal complete, waiting till txg %llu",
!                     tx->tx_txg, scn->scn_done_txg);
          }
  
          if (DSL_SCAN_IS_SCRUB_RESILVER(scn)) {
                  mutex_enter(&spa->spa_scrub_lock);
                  while (spa->spa_scrub_inflight > 0) {