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LU-5395 lfsck: deadlock between LFSCK and destroy
[fs/lustre-release.git] / lustre / lfsck / lfsck_layout.c
index 9cc0192..3db63dc 100644 (file)
@@ -39,7 +39,6 @@
 #include <lustre/lustre_idl.h>
 #include <lu_object.h>
 #include <dt_object.h>
-#include <lustre_linkea.h>
 #include <lustre_fid.h>
 #include <lustre_lib.h>
 #include <lustre_net.h>
@@ -303,8 +302,7 @@ static inline bool lfsck_layout_req_empty(struct lfsck_layout_master_data *llmd)
 }
 
 static int lfsck_layout_get_lovea(const struct lu_env *env,
-                                 struct dt_object *obj,
-                                 struct lu_buf *buf, ssize_t *buflen)
+                                 struct dt_object *obj, struct lu_buf *buf)
 {
        int rc;
 
@@ -317,9 +315,6 @@ again:
                        return rc;
 
                lu_buf_realloc(buf, rc);
-               if (buflen != NULL)
-                       *buflen = buf->lb_len;
-
                if (buf->lb_buf == NULL)
                        return -ENOMEM;
 
@@ -334,9 +329,6 @@ again:
 
        if (unlikely(buf->lb_buf == NULL)) {
                lu_buf_alloc(buf, rc);
-               if (buflen != NULL)
-                       *buflen = buf->lb_len;
-
                if (buf->lb_buf == NULL)
                        return -ENOMEM;
 
@@ -359,7 +351,7 @@ static int lfsck_layout_verify_header(struct lov_mds_md_v1 *lmm)
                struct ost_id   oi;
                int             rc;
 
-               lmm_oi_cpu_to_le(&oi, &lmm->lmm_oi);
+               lmm_oi_le_to_cpu(&oi, &lmm->lmm_oi);
                if ((magic & LOV_MAGIC_MASK) == LOV_MAGIC_MAGIC)
                        rc = -EOPNOTSUPP;
                else
@@ -377,7 +369,7 @@ static int lfsck_layout_verify_header(struct lov_mds_md_v1 *lmm)
        if (lov_pattern(pattern) != LOV_PATTERN_RAID0) {
                struct ost_id oi;
 
-               lmm_oi_cpu_to_le(&oi, &lmm->lmm_oi);
+               lmm_oi_le_to_cpu(&oi, &lmm->lmm_oi);
                CDEBUG(D_LFSCK, "Unsupported LOV EA pattern %u on "DOSTID"\n",
                       pattern, POSTID(&oi));
 
@@ -492,7 +484,7 @@ static struct lfsck_rbtree_node *lfsck_rbtree_new(const struct lu_env *env,
                return ERR_PTR(-ENOMEM);
        }
 
-       rb_init_node(&lrn->lrn_node);
+       RB_CLEAR_NODE(&lrn->lrn_node);
        lrn->lrn_seq = fid_seq(fid);
        lrn->lrn_first_oid = fid_oid(fid) & ~LFSCK_RBTREE_BITMAP_MASK;
        atomic_set(&lrn->lrn_known_count, 0);
@@ -566,6 +558,9 @@ static int lfsck_rbtree_setup(const struct lu_env *env,
        llsd->llsd_rbtree_valid = 1;
        dev->dd_record_fid_accessed = 1;
 
+       CDEBUG(D_LFSCK, "%s: layout LFSCK init OST-objects accessing bitmap\n",
+              lfsck_lfsck2name(lfsck));
+
        return 0;
 }
 
@@ -596,6 +591,9 @@ static void lfsck_rbtree_cleanup(const struct lu_env *env,
                lu_object_put(env, &llsd->llsd_rb_obj->do_lu);
                llsd->llsd_rb_obj = NULL;
        }
+
+       CDEBUG(D_LFSCK, "%s: layout LFSCK fini OST-objects accessing bitmap\n",
+              lfsck_lfsck2name(lfsck));
 }
 
 static void lfsck_rbtree_update_bitmap(const struct lu_env *env,
@@ -610,9 +608,6 @@ static void lfsck_rbtree_update_bitmap(const struct lu_env *env,
        int                              rc     = 0;
        ENTRY;
 
-       CDEBUG(D_LFSCK, "%s: update bitmap for "DFID"\n",
-              lfsck_lfsck2name(com->lc_lfsck), PFID(fid));
-
        if (unlikely(!fid_is_sane(fid) || fid_is_last_id(fid)))
                RETURN_EXIT;
 
@@ -664,24 +659,17 @@ out:
        if (rc != 0 && accessed) {
                struct lfsck_layout *lo = com->lc_file_ram;
 
-               CERROR("%s: Fail to update object accessed bitmap, will cause "
-                      "incorrect LFSCK OST-object handling, so disable it to "
-                      "cancel orphan handling for related device. rc = %d.\n",
+               CDEBUG(D_LFSCK, "%s: fail to update OST-objects accessing "
+                      "bitmap, and will cause incorrect LFSCK OST-object "
+                      "handling, so disable it to cancel orphan handling "
+                      "for related device. rc = %d\n",
                       lfsck_lfsck2name(com->lc_lfsck), rc);
+
                lo->ll_flags |= LF_INCOMPLETE;
                lfsck_rbtree_cleanup(env, com);
        }
 }
 
-static inline bool is_dummy_lov_ost_data(struct lov_ost_data_v1 *obj)
-{
-       if (fid_is_zero(&obj->l_ost_oi.oi_fid) &&
-           obj->l_ost_gen == 0 && obj->l_ost_idx == 0)
-               return true;
-
-       return false;
-}
-
 static void lfsck_layout_le_to_cpu(struct lfsck_layout *des,
                                   const struct lfsck_layout *src)
 {
@@ -760,20 +748,20 @@ static int lfsck_layout_load(const struct lu_env *env,
        if (rc == 0) {
                return -ENOENT;
        } else if (rc < 0) {
-               CWARN("%s: failed to load lfsck_layout: rc = %d\n",
-                     lfsck_lfsck2name(com->lc_lfsck), rc);
+               CDEBUG(D_LFSCK, "%s: failed to load lfsck_layout: rc = %d\n",
+                      lfsck_lfsck2name(com->lc_lfsck), rc);
                return rc;
        } else if (rc != size) {
-               CWARN("%s: crashed lfsck_layout, to be reset: rc = %d\n",
-                     lfsck_lfsck2name(com->lc_lfsck), rc);
+               CDEBUG(D_LFSCK, "%s: lfsck_layout size %u != %u; reset it\n",
+                      lfsck_lfsck2name(com->lc_lfsck), rc, (unsigned int)size);
                return 1;
        }
 
        lfsck_layout_le_to_cpu(lo, com->lc_file_disk);
        if (lo->ll_magic != LFSCK_LAYOUT_MAGIC) {
-               CWARN("%s: invalid lfsck_layout magic %#x != %#x, "
-                     "to be reset\n", lfsck_lfsck2name(com->lc_lfsck),
-                     lo->ll_magic, LFSCK_LAYOUT_MAGIC);
+               CDEBUG(D_LFSCK, "%s: invalid lfsck_layout magic %#x != %#x, "
+                      "to be reset\n", lfsck_lfsck2name(com->lc_lfsck),
+                      lo->ll_magic, LFSCK_LAYOUT_MAGIC);
                return 1;
        }
 
@@ -794,39 +782,30 @@ static int lfsck_layout_store(const struct lu_env *env,
 
        lfsck_layout_cpu_to_le(lo, com->lc_file_ram);
        handle = dt_trans_create(env, lfsck->li_bottom);
-       if (IS_ERR(handle)) {
-               rc = PTR_ERR(handle);
-               CERROR("%s: fail to create trans for storing lfsck_layout: "
-                      "rc = %d\n", lfsck_lfsck2name(lfsck), rc);
-               RETURN(rc);
-       }
+       if (IS_ERR(handle))
+               GOTO(log, rc = PTR_ERR(handle));
 
        rc = dt_declare_record_write(env, obj, lfsck_buf_get(env, lo, size),
                                     pos, handle);
-       if (rc != 0) {
-               CERROR("%s: fail to declare trans for storing lfsck_layout(1): "
-                      "rc = %d\n", lfsck_lfsck2name(lfsck), rc);
+       if (rc != 0)
                GOTO(out, rc);
-       }
 
        rc = dt_trans_start_local(env, lfsck->li_bottom, handle);
-       if (rc != 0) {
-               CERROR("%s: fail to start trans for storing lfsck_layout: "
-                      "rc = %d\n", lfsck_lfsck2name(lfsck), rc);
+       if (rc != 0)
                GOTO(out, rc);
-       }
 
        rc = dt_record_write(env, obj, lfsck_buf_get(env, lo, size), &pos,
                             handle);
-       if (rc != 0)
-               CERROR("%s: fail to store lfsck_layout(1): size = %d, "
-                      "rc = %d\n", lfsck_lfsck2name(lfsck), (int)size, rc);
 
        GOTO(out, rc);
 
 out:
        dt_trans_stop(env, lfsck->li_bottom, handle);
 
+log:
+       if (rc != 0)
+               CDEBUG(D_LFSCK, "%s: fail to store lfsck_layout: rc = %d\n",
+                      lfsck_lfsck2name(lfsck), rc);
        return rc;
 }
 
@@ -925,9 +904,6 @@ lfsck_layout_lastid_create(const struct lu_env *env,
        int                       rc;
        ENTRY;
 
-       CDEBUG(D_LFSCK, "To create LAST_ID for <seq> "LPX64"\n",
-              fid_seq(lfsck_dto2fid(obj)));
-
        if (bk->lb_param & LPF_DRYRUN)
                return 0;
 
@@ -938,7 +914,7 @@ lfsck_layout_lastid_create(const struct lu_env *env,
 
        th = dt_trans_create(env, dt);
        if (IS_ERR(th))
-               RETURN(rc = PTR_ERR(th));
+               GOTO(log, rc = PTR_ERR(th));
 
        rc = dt_declare_create(env, obj, la, NULL, dof, th);
        if (rc != 0)
@@ -956,7 +932,7 @@ lfsck_layout_lastid_create(const struct lu_env *env,
                GOTO(stop, rc);
 
        dt_write_lock(env, obj, 0);
-       if (likely(!dt_object_exists(obj))) {
+       if (likely(dt_object_exists(obj) == 0)) {
                rc = dt_create(env, obj, la, NULL, dof, th);
                if (rc == 0)
                        rc = dt_record_write(env, obj,
@@ -970,6 +946,11 @@ lfsck_layout_lastid_create(const struct lu_env *env,
 stop:
        dt_trans_stop(env, dt, th);
 
+log:
+       CDEBUG(D_LFSCK, "%s: layout LFSCK will create LAST_ID for <seq> "
+              LPX64": rc = %d\n",
+              lfsck_lfsck2name(lfsck), fid_seq(lfsck_dto2fid(obj)), rc);
+
        return rc;
 }
 
@@ -1002,6 +983,12 @@ lfsck_layout_lastid_reload(const struct lu_env *env,
                        lfsck->li_out_notify(env, lfsck->li_out_notify_data,
                                             LE_LASTID_REBUILDING);
                        lo->ll_flags |= LF_CRASHED_LASTID;
+
+                       CDEBUG(D_LFSCK, "%s: layout LFSCK finds crashed "
+                              "LAST_ID file (1) for the sequence "LPX64
+                              ", old value "LPU64", known value "LPU64"\n",
+                              lfsck_lfsck2name(lfsck), lls->lls_seq,
+                              lastid, lls->lls_lastid);
                }
        } else if (lastid >= lls->lls_lastid) {
                lls->lls_lastid = lastid;
@@ -1028,30 +1015,12 @@ lfsck_layout_lastid_store(const struct lu_env *env,
        list_for_each_entry(lls, &llsd->llsd_seq_list, lls_list) {
                loff_t pos = 0;
 
-               /* XXX: Add the code back if we really found related
-                *      inconsistent cases in the future. */
-#if 0
-               if (!lls->lls_dirty) {
-                       /* In OFD, before the pre-creation, the LAST_ID
-                        * file will be updated firstly, which may hide
-                        * some potential crashed cases. For example:
-                        *
-                        * The old obj1's ID is higher than old LAST_ID
-                        * but lower than the new LAST_ID, but the LFSCK
-                        * have not touch the obj1 until the OFD updated
-                        * the LAST_ID. So the LFSCK does not regard it
-                        * as crashed case. But when OFD does not create
-                        * successfully, it will set the LAST_ID as the
-                        * real created objects' ID, then LFSCK needs to
-                        * found related inconsistency. */
-                       rc = lfsck_layout_lastid_reload(env, com, lls);
-                       if (likely(!lls->lls_dirty))
-                               continue;
-               }
-#endif
+               if (!lls->lls_dirty)
+                       continue;
 
-               CDEBUG(D_LFSCK, "To sync the LAST_ID for <seq> "LPX64
-                      " as <oid> "LPU64"\n", lls->lls_seq, lls->lls_lastid);
+               CDEBUG(D_LFSCK, "%s: layout LFSCK will sync the LAST_ID for "
+                      "<seq> "LPX64" as <oid> "LPU64"\n",
+                      lfsck_lfsck2name(lfsck), lls->lls_seq, lls->lls_lastid);
 
                if (bk->lb_param & LPF_DRYRUN) {
                        lls->lls_dirty = 0;
@@ -1061,7 +1030,8 @@ lfsck_layout_lastid_store(const struct lu_env *env,
                th = dt_trans_create(env, dt);
                if (IS_ERR(th)) {
                        rc1 = PTR_ERR(th);
-                       CERROR("%s: (1) failed to store "LPX64": rc = %d\n",
+                       CDEBUG(D_LFSCK, "%s: layout LFSCK failed to store "
+                              "the LAST_ID for <seq> "LPX64"(1): rc = %d\n",
                               lfsck_lfsck2name(com->lc_lfsck),
                               lls->lls_seq, rc1);
                        continue;
@@ -1091,7 +1061,8 @@ stop:
                dt_trans_stop(env, dt, th);
                if (rc != 0) {
                        rc1 = rc;
-                       CERROR("%s: (2) failed to store "LPX64": rc = %d\n",
+                       CDEBUG(D_LFSCK, "%s: layout LFSCK failed to store "
+                              "the LAST_ID for <seq> "LPX64"(2): rc = %d\n",
                               lfsck_lfsck2name(com->lc_lfsck),
                               lls->lls_seq, rc1);
                }
@@ -1119,7 +1090,7 @@ lfsck_layout_lastid_load(const struct lu_env *env,
                RETURN(PTR_ERR(obj));
 
        /* LAST_ID crashed, to be rebuilt */
-       if (!dt_object_exists(obj)) {
+       if (dt_object_exists(obj) == 0) {
                if (!(lo->ll_flags & LF_CRASHED_LASTID)) {
                        LASSERT(lfsck->li_out_notify != NULL);
 
@@ -1127,6 +1098,10 @@ lfsck_layout_lastid_load(const struct lu_env *env,
                                             LE_LASTID_REBUILDING);
                        lo->ll_flags |= LF_CRASHED_LASTID;
 
+                       CDEBUG(D_LFSCK, "%s: layout LFSCK cannot find the "
+                              "LAST_ID file for sequence "LPX64"\n",
+                              lfsck_lfsck2name(lfsck), lls->lls_seq);
+
                        if (OBD_FAIL_CHECK(OBD_FAIL_LFSCK_DELAY4) &&
                            cfs_fail_val > 0) {
                                struct l_wait_info lwi = LWI_TIMEOUT(
@@ -1157,6 +1132,11 @@ lfsck_layout_lastid_load(const struct lu_env *env,
                        lfsck->li_out_notify(env, lfsck->li_out_notify_data,
                                             LE_LASTID_REBUILDING);
                        lo->ll_flags |= LF_CRASHED_LASTID;
+
+                       CDEBUG(D_LFSCK, "%s: layout LFSCK finds invalid "
+                              "LAST_ID file for the sequence "LPX64
+                              ": rc = %d\n",
+                              lfsck_lfsck2name(lfsck), lls->lls_seq, rc);
                }
 
                lls->lls_lastid = le64_to_cpu(lls->lls_lastid);
@@ -1179,10 +1159,16 @@ static void lfsck_layout_record_failure(const struct lu_env *env,
                                                 struct lfsck_layout *lo)
 {
        lo->ll_objs_failed_phase1++;
-       if (unlikely(lo->ll_pos_first_inconsistent == 0))
+       if (unlikely(lo->ll_pos_first_inconsistent == 0)) {
                lo->ll_pos_first_inconsistent =
                        lfsck->li_obj_oit->do_index_ops->dio_it.store(env,
                                                        lfsck->li_di_oit);
+
+               CDEBUG(D_LFSCK, "%s: layout LFSCK hit first non-repaired "
+                      "inconsistency at the pos ["LPU64"]\n",
+                      lfsck_lfsck2name(lfsck),
+                      lo->ll_pos_first_inconsistent);
+       }
 }
 
 static int lfsck_layout_master_async_interpret(const struct lu_env *env,
@@ -1201,8 +1187,9 @@ static int lfsck_layout_master_async_interpret(const struct lu_env *env,
                if (rc != 0) {
                        struct lfsck_layout *lo = com->lc_file_ram;
 
-                       CERROR("%s: fail to notify %s %x for layout start: "
-                              "rc = %d\n", lfsck_lfsck2name(com->lc_lfsck),
+                       CDEBUG(D_LFSCK, "%s: fail to notify %s %x for layout "
+                              "start: rc = %d\n",
+                              lfsck_lfsck2name(com->lc_lfsck),
                               (lr->lr_flags & LEF_TO_OST) ? "OST" : "MDT",
                               ltd->ltd_index, rc);
                        lo->ll_flags |= LF_INCOMPLETE;
@@ -1237,11 +1224,11 @@ static int lfsck_layout_master_async_interpret(const struct lu_env *env,
        case LE_PHASE2_DONE:
        case LE_PEER_EXIT:
                if (rc != 0 && rc != -EALREADY)
-                       CWARN("%s: fail to notify %s %x for layout: "
-                             "event = %d, rc = %d\n",
-                             lfsck_lfsck2name(com->lc_lfsck),
-                             (lr->lr_flags & LEF_TO_OST) ? "OST" : "MDT",
-                             ltd->ltd_index, lr->lr_event, rc);
+                       CDEBUG(D_LFSCK, "%s: fail to notify %s %x for layout: "
+                              "event = %d, rc = %d\n",
+                              lfsck_lfsck2name(com->lc_lfsck),
+                              (lr->lr_flags & LEF_TO_OST) ? "OST" : "MDT",
+                              ltd->ltd_index, lr->lr_event, rc);
                break;
        case LE_QUERY: {
                struct lfsck_reply *reply;
@@ -1258,7 +1245,7 @@ static int lfsck_layout_master_async_interpret(const struct lu_env *env,
                                               &RMF_LFSCK_REPLY);
                if (reply == NULL) {
                        rc = -EPROTO;
-                       CERROR("%s: invalid return value: rc = %d\n",
+                       CDEBUG(D_LFSCK, "%s:  invalid query reply: rc = %d\n",
                               lfsck_lfsck2name(com->lc_lfsck), rc);
                        spin_lock(&ltds->ltd_lock);
                        list_del_init(&ltd->ltd_layout_phase_list);
@@ -1296,7 +1283,7 @@ static int lfsck_layout_master_async_interpret(const struct lu_env *env,
                break;
        }
        default:
-               CERROR("%s: unexpected event: rc = %d\n",
+               CDEBUG(D_LFSCK, "%s: layout LFSCK unexpected event: rc = %d\n",
                       lfsck_lfsck2name(com->lc_lfsck), lr->lr_event);
                break;
        }
@@ -1333,7 +1320,7 @@ static int lfsck_layout_master_query_others(const struct lu_env *env,
        memset(lr, 0, sizeof(*lr));
        lr->lr_index = lfsck_dev_idx(lfsck->li_bottom);
        lr->lr_event = LE_QUERY;
-       lr->lr_active = LT_LAYOUT;
+       lr->lr_active = LFSCK_TYPE_LAYOUT;
        laia->laia_com = com;
        laia->laia_lr = lr;
        laia->laia_shared = 0;
@@ -1360,8 +1347,7 @@ again:
                        break;
 
                ltd->ltd_layout_gen = llmd->llmd_touch_gen;
-               list_del(&ltd->ltd_layout_phase_list);
-               list_add_tail(&ltd->ltd_layout_phase_list, head);
+               list_move_tail(&ltd->ltd_layout_phase_list, head);
                atomic_inc(&ltd->ltd_ref);
                laia->laia_ltd = ltd;
                spin_unlock(&ltds->ltd_lock);
@@ -1369,8 +1355,8 @@ again:
                                         lfsck_layout_master_async_interpret,
                                         laia, LFSCK_QUERY);
                if (rc != 0) {
-                       CERROR("%s: fail to query %s %x for layout: rc = %d\n",
-                              lfsck_lfsck2name(lfsck),
+                       CDEBUG(D_LFSCK, "%s: layout LFSCK fail to query %s %x: "
+                              "rc = %d\n", lfsck_lfsck2name(lfsck),
                               (lr->lr_flags & LEF_TO_OST) ? "OST" : "MDT",
                               ltd->ltd_index, rc);
                        lfsck_tgt_put(ltd);
@@ -1427,7 +1413,7 @@ static int lfsck_layout_master_notify_others(const struct lu_env *env,
                RETURN(-ENOMEM);
 
        lr->lr_index = lfsck_dev_idx(lfsck->li_bottom);
-       lr->lr_active = LT_LAYOUT;
+       lr->lr_active = LFSCK_TYPE_LAYOUT;
        laia->laia_com = com;
        laia->laia_lr = lr;
        laia->laia_shared = 0;
@@ -1447,8 +1433,8 @@ static int lfsck_layout_master_notify_others(const struct lu_env *env,
                                        lfsck_layout_master_async_interpret,
                                        laia, LFSCK_NOTIFY);
                        if (rc != 0) {
-                               CERROR("%s: fail to notify %s %x for layout "
-                                      "start: rc = %d\n",
+                               CDEBUG(D_LFSCK, "%s: layout LFSCK fail to "
+                                      "notify %s %x for start: rc = %d\n",
                                       lfsck_lfsck2name(lfsck),
                                       (lr->lr_flags & LEF_TO_OST) ? "OST" :
                                       "MDT", idx, rc);
@@ -1469,6 +1455,7 @@ static int lfsck_layout_master_notify_others(const struct lu_env *env,
                        break;
 
                /* link other MDT targets locallly. */
+               ltds = &lfsck->li_mdt_descs;
                spin_lock(&ltds->ltd_lock);
                cfs_foreach_bit(ltds->ltd_tgts_bitmap, idx) {
                        ltd = LTD_TGT(ltds, idx);
@@ -1529,8 +1516,9 @@ again:
                                        lfsck_layout_master_async_interpret,
                                        laia, LFSCK_NOTIFY);
                        if (rc != 0) {
-                               CERROR("%s: fail to notify %s %x for layout "
-                                      "stop/phase2: rc = %d\n",
+                               CDEBUG(D_LFSCK, "%s: layout LFSCK fail to "
+                                      "notify %s %x for stop/phase2_done/"
+                                      "peer_exit: rc = %d\n",
                                       lfsck_lfsck2name(lfsck),
                                       (lr->lr_flags & LEF_TO_OST) ? "OST" :
                                       "MDT", ltd->ltd_index, rc);
@@ -1567,9 +1555,8 @@ again:
                                break;
 
                        ltd->ltd_layout_gen = llmd->llmd_touch_gen;
-                       list_del_init(&ltd->ltd_layout_phase_list);
-                       list_add_tail(&ltd->ltd_layout_phase_list,
-                                     &llmd->llmd_mdt_phase1_list);
+                       list_move_tail(&ltd->ltd_layout_phase_list,
+                                      &llmd->llmd_mdt_phase1_list);
                        atomic_inc(&ltd->ltd_ref);
                        laia->laia_ltd = ltd;
                        spin_unlock(&ltds->ltd_lock);
@@ -1577,9 +1564,9 @@ again:
                                        lfsck_layout_master_async_interpret,
                                        laia, LFSCK_NOTIFY);
                        if (rc != 0) {
-                               CERROR("%s: fail to notify MDT %x for layout "
-                                      "phase1 done: rc = %d\n",
-                                      lfsck_lfsck2name(lfsck),
+                               CDEBUG(D_LFSCK, "%s: layout LFSCK fail to "
+                                      "notify MDT %x for phase1_done: "
+                                      "rc = %d\n", lfsck_lfsck2name(lfsck),
                                       ltd->ltd_index, rc);
                                lfsck_tgt_put(ltd);
                        }
@@ -1588,7 +1575,7 @@ again:
                spin_unlock(&ltds->ltd_lock);
                break;
        default:
-               CERROR("%s: unexpected LFSCK event: rc = %d\n",
+               CDEBUG(D_LFSCK, "%s: layout LFSCK unexpected event: rc = %d\n",
                       lfsck_lfsck2name(lfsck), lr->lr_event);
                rc = -EINVAL;
                break;
@@ -1694,6 +1681,45 @@ static int lfsck_layout_trans_stop(const struct lu_env *env,
 }
 
 /**
+ * Get the system default stripe size.
+ *
+ * \param[in] env      pointer to the thread context
+ * \param[in] lfsck    pointer to the lfsck instance
+ * \param[out] size    pointer to the default stripe size
+ *
+ * \retval             0 for success
+ * \retval             negative error number on failure
+ */
+static int lfsck_layout_get_def_stripesize(const struct lu_env *env,
+                                          struct lfsck_instance *lfsck,
+                                          __u32 *size)
+{
+       struct lov_user_md      *lum = &lfsck_env_info(env)->lti_lum;
+       struct dt_object        *root;
+       int                      rc;
+
+       root = dt_locate(env, lfsck->li_next, &lfsck->li_local_root_fid);
+       if (IS_ERR(root))
+               return PTR_ERR(root);
+
+       /* Get the default stripe size via xattr_get on the backend root. */
+       rc = dt_xattr_get(env, root, lfsck_buf_get(env, lum, sizeof(*lum)),
+                         XATTR_NAME_LOV, BYPASS_CAPA);
+       if (rc > 0) {
+               /* The lum->lmm_stripe_size is LE mode. The *size also
+                * should be LE mode. So it is unnecessary to convert. */
+               *size = lum->lmm_stripe_size;
+               rc = 0;
+       } else if (unlikely(rc == 0)) {
+               rc = -EINVAL;
+       }
+
+       lfsck_object_put(env, root);
+
+       return rc;
+}
+
+/**
  * \retval      +1: repaired
  * \retval       0: did nothing
  * \retval     -ve: on error
@@ -1706,14 +1732,42 @@ static int lfsck_layout_refill_lovea(const struct lu_env *env,
                                     struct lov_ost_data_v1 *slot,
                                     int fl, __u32 ost_idx)
 {
-       struct ost_id   *oi     = &lfsck_env_info(env)->lti_oi;
-       int              rc;
+       struct ost_id           *oi     = &lfsck_env_info(env)->lti_oi;
+       struct lov_mds_md_v1    *lmm    = buf->lb_buf;
+       struct lu_buf            ea_buf;
+       int                      rc;
+       __u32                    magic;
+       __u16                    count;
+
+       magic = le32_to_cpu(lmm->lmm_magic);
+       count = le16_to_cpu(lmm->lmm_stripe_count);
 
        fid_to_ostid(cfid, oi);
        ostid_cpu_to_le(oi, &slot->l_ost_oi);
        slot->l_ost_gen = cpu_to_le32(0);
        slot->l_ost_idx = cpu_to_le32(ost_idx);
-       rc = dt_xattr_set(env, parent, buf, XATTR_NAME_LOV, fl, handle,
+
+       if (le32_to_cpu(lmm->lmm_pattern) & LOV_PATTERN_F_HOLE) {
+               struct lov_ost_data_v1 *objs;
+               int                     i;
+
+               if (magic == LOV_MAGIC_V1)
+                       objs = &lmm->lmm_objects[0];
+               else
+                       objs = &((struct lov_mds_md_v3 *)lmm)->lmm_objects[0];
+               for (i = 0; i < count; i++, objs++) {
+                       if (objs != slot && lovea_slot_is_dummy(objs))
+                               break;
+               }
+
+               /* If the @slot is the last dummy slot to be refilled,
+                * then drop LOV_PATTERN_F_HOLE from lmm::lmm_pattern. */
+               if (i == count)
+                       lmm->lmm_pattern &= ~cpu_to_le32(LOV_PATTERN_F_HOLE);
+       }
+
+       lfsck_buf_init(&ea_buf, lmm, lov_mds_md_size(count, magic));
+       rc = dt_xattr_set(env, parent, &ea_buf, XATTR_NAME_LOV, fl, handle,
                          BYPASS_CAPA);
        if (rc == 0)
                rc = 1;
@@ -1727,6 +1781,7 @@ static int lfsck_layout_refill_lovea(const struct lu_env *env,
  * \retval     -ve: on error
  */
 static int lfsck_layout_extend_lovea(const struct lu_env *env,
+                                    struct lfsck_instance *lfsck,
                                     struct thandle *handle,
                                     struct dt_object *parent,
                                     struct lu_fid *cfid,
@@ -1736,53 +1791,71 @@ static int lfsck_layout_extend_lovea(const struct lu_env *env,
        struct lov_mds_md_v1    *lmm    = buf->lb_buf;
        struct lov_ost_data_v1  *objs;
        int                      rc;
+       __u16                    count;
+       bool                     hole   = false;
        ENTRY;
 
        if (fl == LU_XATTR_CREATE || reset) {
-               LASSERT(buf->lb_len == lov_mds_md_size(ea_off + 1,
-                                                      LOV_MAGIC_V1));
+               __u32 pattern = LOV_PATTERN_RAID0;
+
+               count = ea_off + 1;
+               LASSERT(buf->lb_len >= lov_mds_md_size(count, LOV_MAGIC_V1));
+
+               if (ea_off != 0 || reset) {
+                       pattern |= LOV_PATTERN_F_HOLE;
+                       hole = true;
+               }
 
                memset(lmm, 0, buf->lb_len);
                lmm->lmm_magic = cpu_to_le32(LOV_MAGIC_V1);
-               /* XXX: currently, we only support LOV_PATTERN_RAID0. */
-               lmm->lmm_pattern = cpu_to_le32(LOV_PATTERN_RAID0);
+               lmm->lmm_pattern = cpu_to_le32(pattern);
                fid_to_lmm_oi(lfsck_dto2fid(parent), &lmm->lmm_oi);
                lmm_oi_cpu_to_le(&lmm->lmm_oi, &lmm->lmm_oi);
-               /* XXX: We cannot know the stripe size,
-                *      then use the default value (1 MB). */
-               lmm->lmm_stripe_size =
-                       cpu_to_le32(LOV_DESC_STRIPE_SIZE_DEFAULT);
-               objs = &(lmm->lmm_objects[ea_off]);
+
+               rc = lfsck_layout_get_def_stripesize(env, lfsck,
+                                                    &lmm->lmm_stripe_size);
+               if (rc != 0)
+                       RETURN(rc);
+
+               objs = &lmm->lmm_objects[ea_off];
        } else {
-               __u16   count = le16_to_cpu(lmm->lmm_stripe_count);
-               int     gap   = ea_off - count;
                __u32   magic = le32_to_cpu(lmm->lmm_magic);
+               int     gap;
 
-               /* Currently, we only support LOV_MAGIC_V1/LOV_MAGIC_V3
-                * which has been verified in lfsck_layout_verify_header()
-                * already. If some new magic introduced in the future,
-                * then layout LFSCK needs to be updated also. */
-               if (magic == LOV_MAGIC_V1) {
-                       objs = &(lmm->lmm_objects[count]);
-               } else {
-                       LASSERT(magic == LOV_MAGIC_V3);
+               count = le16_to_cpu(lmm->lmm_stripe_count);
+               if (magic == LOV_MAGIC_V1)
+                       objs = &lmm->lmm_objects[count];
+               else
                        objs = &((struct lov_mds_md_v3 *)lmm)->
                                                        lmm_objects[count];
-               }
 
-               if (gap > 0)
+               gap = ea_off - count;
+               if (gap >= 0)
+                       count = ea_off + 1;
+               LASSERT(buf->lb_len >= lov_mds_md_size(count, magic));
+
+               if (gap > 0) {
                        memset(objs, 0, gap * sizeof(*objs));
+                       lmm->lmm_pattern |= cpu_to_le32(LOV_PATTERN_F_HOLE);
+                       hole = true;
+               }
+
                lmm->lmm_layout_gen =
                            cpu_to_le16(le16_to_cpu(lmm->lmm_layout_gen) + 1);
                objs += gap;
-
-               LASSERT(buf->lb_len == lov_mds_md_size(ea_off + 1, magic));
        }
 
-       lmm->lmm_stripe_count = cpu_to_le16(ea_off + 1);
+       lmm->lmm_stripe_count = cpu_to_le16(count);
        rc = lfsck_layout_refill_lovea(env, handle, parent, cfid, buf, objs,
                                       fl, ost_idx);
 
+       CDEBUG(D_LFSCK, "%s: layout LFSCK assistant extend layout EA for "
+              DFID": parent "DFID", OST-index %u, stripe-index %u, fl %d, "
+              "reset %s, %s LOV EA hole: rc = %d\n",
+              lfsck_lfsck2name(lfsck), PFID(cfid), PFID(lfsck_dto2fid(parent)),
+              ost_idx, ea_off, fl, reset ? "yes" : "no",
+              hole ? "with" : "without", rc);
+
        RETURN(rc);
 }
 
@@ -1844,20 +1917,61 @@ out:
 }
 
 /**
- * \retval      +1: repaired
- * \retval       0: did nothing
- * \retval     -ve: on error
+ * This function will create the MDT-object with the given (partial) LOV EA.
+ *
+ * Under some data corruption cases, the MDT-object of the file may be lost,
+ * but its OST-objects, or some of them are there. The layout LFSCK needs to
+ * re-create the MDT-object with the orphan OST-object(s) information.
+ *
+ * On the other hand, the LFSCK may has created some OST-object for repairing
+ * dangling LOV EA reference, but as the LFSCK processing, it may find that
+ * the old OST-object is there and should replace the former new created OST
+ * object. Unfortunately, some others have modified such newly created object.
+ * To keep the data (both new and old), the LFSCK will create MDT-object with
+ * new FID to reference the original OST-object.
+ *
+ * \param[in] env      pointer to the thread context
+ * \param[in] com      pointer to the lfsck component
+ * \param[in] ltd      pointer to target device descriptor
+ * \param[in] rec      pointer to the record for the orphan OST-object
+ * \param[in] cfid     pointer to FID for the orphan OST-object
+ * \param[in] infix    additional information, such as the FID for original
+ *                     MDT-object and the stripe offset in the LOV EA
+ * \param[in] type     the type for describing why the orphan MDT-object is
+ *                     created. The rules are as following:
+ *
+ *  type "C":          Multiple OST-objects claim the same MDT-object and the
+ *                     same slot in the layout EA. Then the LFSCK will create
+ *                     new MDT-object(s) to hold the conflict OST-object(s).
+ *
+ *  type "N":          The orphan OST-object does not know which one was the
+ *                     real parent MDT-object, so the LFSCK uses new FID for
+ *                     its parent MDT-object.
+ *
+ *  type "R":          The orphan OST-object knows its parent MDT-object FID,
+ *                     but does not know the position (the file name) in the
+ *                     namespace.
+ *
+ * The orphan name will be like:
+ * ${FID}-${infix}-${type}-${conflict_version}
+ *
+ * \param[in] ea_off   the stripe offset in the LOV EA
+ *
+ * \retval             positive on repaired something
+ * \retval             0 if needs to repair nothing
+ * \retval             negative error number on failure
  */
 static int lfsck_layout_recreate_parent(const struct lu_env *env,
                                        struct lfsck_component *com,
                                        struct lfsck_tgt_desc *ltd,
                                        struct lu_orphan_rec *rec,
                                        struct lu_fid *cfid,
-                                       const char *prefix,
-                                       const char *postfix,
+                                       const char *infix,
+                                       const char *type,
                                        __u32 ea_off)
 {
        struct lfsck_thread_info        *info   = lfsck_env_info(env);
+       struct dt_insert_rec            *dtrec  = &info->lti_dt_rec;
        char                            *name   = info->lti_key;
        struct lu_attr                  *la     = &info->lti_la;
        struct dt_object_format         *dof    = &info->lti_dof;
@@ -1868,10 +1982,14 @@ static int lfsck_layout_recreate_parent(const struct lu_env *env,
        struct dt_object                *pobj   = NULL;
        struct dt_object                *cobj   = NULL;
        struct thandle                  *th     = NULL;
-       struct lu_buf                   *pbuf   = NULL;
+       struct lu_buf                    pbuf   = { 0 };
        struct lu_buf                   *ea_buf = &info->lti_big_buf;
+       struct lu_buf                    lov_buf;
        struct lustre_handle             lh     = { 0 };
-       int                              buflen = ea_buf->lb_len;
+       struct linkea_data               ldata  = { 0 };
+       struct lu_buf                    linkea_buf;
+       const struct lu_name            *pname;
+       int                              size   = 0;
        int                              idx    = 0;
        int                              rc     = 0;
        ENTRY;
@@ -1880,7 +1998,7 @@ static int lfsck_layout_recreate_parent(const struct lu_env *env,
        if (unlikely(lfsck->li_lpf_obj == NULL)) {
                rc = lfsck_create_lpf(env, lfsck);
                if (rc != 0)
-                       RETURN(rc);
+                       GOTO(log, rc);
        }
 
        if (fid_is_zero(pfid)) {
@@ -1896,73 +2014,52 @@ static int lfsck_layout_recreate_parent(const struct lu_env *env,
                 * real parent MDT-object's FID::f_ver, instead it is the
                 * OST-object index in its parent MDT-object's layout EA. */
                ff->ff_parent.f_stripe_idx = cpu_to_le32(ea_off);
-               pbuf = lfsck_buf_get(env, ff, sizeof(struct filter_fid));
+               lfsck_buf_init(&pbuf, ff, sizeof(struct filter_fid));
                cobj = lfsck_object_find_by_dev(env, ltd->ltd_tgt, cfid);
                if (IS_ERR(cobj))
-                       RETURN(PTR_ERR(cobj));
+                       GOTO(log, rc = PTR_ERR(cobj));
        }
 
-       CDEBUG(D_LFSCK, "Re-create the lost MDT-object: parent "
-              DFID", child "DFID", OST-index %u, stripe-index %u, "
-              "prefix %s, postfix %s\n",
-              PFID(pfid), PFID(cfid), ltd->ltd_index, ea_off, prefix, postfix);
-
        pobj = lfsck_object_find_by_dev(env, lfsck->li_bottom, pfid);
        if (IS_ERR(pobj))
                GOTO(put, rc = PTR_ERR(pobj));
 
-       LASSERT(prefix != NULL);
-       LASSERT(postfix != NULL);
+       LASSERT(infix != NULL);
+       LASSERT(type != NULL);
 
-       /** name rules:
-        *
-        *  1. Use the MDT-object's FID as the name with prefix and postfix.
-        *
-        *  1.1 prefix "C-":    More than one OST-objects claim the same
-        *                      MDT-object and the same slot in the layout EA.
-        *                      It may be created for dangling referenced MDT
-        *                      object or may be not.
-        *  1.2 prefix "N-":    The orphan OST-object does not know which one
-        *                      is the real parent, so the LFSCK assign a new
-        *                      FID as its parent.
-        *  1.3 prefix "R-":    The orphan OST-object know its parent FID but
-        *                      does not know the position in the namespace.
-        *
-        *  2. If there is name conflict, append more index for new name. */
-       sprintf(name, "%s"DFID"%s", prefix, PFID(pfid), postfix);
        do {
+               snprintf(name, NAME_MAX, DFID"%s-%s-%d", PFID(pfid), infix,
+                        type, idx++);
                rc = dt_lookup(env, lfsck->li_lpf_obj, (struct dt_rec *)tfid,
                               (const struct dt_key *)name, BYPASS_CAPA);
                if (rc != 0 && rc != -ENOENT)
                        GOTO(put, rc);
-
-               if (unlikely(rc == 0)) {
-                       CWARN("%s: The name %s under lost+found has been used "
-                             "by the "DFID". Try to increase the FID version "
-                             "for the new file name.\n",
-                             lfsck_lfsck2name(lfsck), name, PFID(tfid));
-                       sprintf(name, "%s"DFID"%s-%d", prefix, PFID(pfid),
-                               postfix, ++idx);
-               }
        } while (rc == 0);
 
+       rc = linkea_data_new(&ldata,
+                            &lfsck_env_info(env)->lti_linkea_buf);
+       if (rc != 0)
+               GOTO(put, rc);
+
+       pname = lfsck_name_get_const(env, name, strlen(name));
+       rc = linkea_add_buf(&ldata, pname, lfsck_dto2fid(lfsck->li_lpf_obj));
+       if (rc != 0)
+               GOTO(put, rc);
+
        memset(la, 0, sizeof(*la));
        la->la_uid = rec->lor_uid;
        la->la_gid = rec->lor_gid;
-       la->la_mode = S_IFREG | S_IRUSR | S_IWUSR;
+       la->la_mode = S_IFREG | S_IRUSR;
        la->la_valid = LA_MODE | LA_UID | LA_GID;
 
        memset(dof, 0, sizeof(*dof));
        dof->dof_type = dt_mode_to_dft(S_IFREG);
 
-       rc = lov_mds_md_size(ea_off + 1, LOV_MAGIC_V1);
-       if (buflen < rc) {
-               lu_buf_realloc(ea_buf, rc);
-               buflen = ea_buf->lb_len;
+       size = lov_mds_md_size(ea_off + 1, LOV_MAGIC_V1);
+       if (ea_buf->lb_len < size) {
+               lu_buf_realloc(ea_buf, size);
                if (ea_buf->lb_buf == NULL)
                        GOTO(put, rc = -ENOMEM);
-       } else {
-               ea_buf->lb_len = rc;
        }
 
        /* Hold update lock on the .lustre/lost+found/MDTxxxx/.
@@ -1985,7 +2082,8 @@ static int lfsck_layout_recreate_parent(const struct lu_env *env,
         * If other subsequent modifications failed, then next LFSCK scanning
         * will process the OST-object as orphan again with known parent FID. */
        if (cobj != NULL) {
-               rc = dt_declare_xattr_set(env, cobj, pbuf, XATTR_NAME_FID, 0, th);
+               rc = dt_declare_xattr_set(env, cobj, &pbuf, XATTR_NAME_FID,
+                                         0, th);
                if (rc != 0)
                        GOTO(stop, rc);
        }
@@ -1996,25 +2094,36 @@ static int lfsck_layout_recreate_parent(const struct lu_env *env,
                GOTO(stop, rc);
 
        /* 3a. Add layout EA for the MDT-object. */
-       rc = dt_declare_xattr_set(env, pobj, ea_buf, XATTR_NAME_LOV,
+       lfsck_buf_init(&lov_buf, ea_buf->lb_buf, size);
+       rc = dt_declare_xattr_set(env, pobj, &lov_buf, XATTR_NAME_LOV,
                                  LU_XATTR_CREATE, th);
        if (rc != 0)
                GOTO(stop, rc);
 
        /* 4a. Insert the MDT-object to .lustre/lost+found/MDTxxxx/ */
+       dtrec->rec_fid = pfid;
+       dtrec->rec_type = S_IFREG;
        rc = dt_declare_insert(env, lfsck->li_lpf_obj,
-                              (const struct dt_rec *)pfid,
+                              (const struct dt_rec *)dtrec,
                               (const struct dt_key *)name, th);
        if (rc != 0)
                GOTO(stop, rc);
 
+       /* 5a. insert linkEA for parent. */
+       lfsck_buf_init(&linkea_buf, ldata.ld_buf->lb_buf,
+                      ldata.ld_leh->leh_len);
+       rc = dt_declare_xattr_set(env, pobj, &linkea_buf,
+                                 XATTR_NAME_LINK, 0, th);
+       if (rc != 0)
+               GOTO(stop, rc);
+
        rc = dt_trans_start(env, next, th);
        if (rc != 0)
                GOTO(stop, rc);
 
        /* 1b. Update OST-object's parent information remotely. */
        if (cobj != NULL) {
-               rc = dt_xattr_set(env, cobj, pbuf, XATTR_NAME_FID, 0, th,
+               rc = dt_xattr_set(env, cobj, &pbuf, XATTR_NAME_FID, 0, th,
                                  BYPASS_CAPA);
                if (rc != 0)
                        GOTO(stop, rc);
@@ -2025,17 +2134,22 @@ static int lfsck_layout_recreate_parent(const struct lu_env *env,
        rc = dt_create(env, pobj, la, NULL, dof, th);
        if (rc == 0)
                /* 3b. Add layout EA for the MDT-object. */
-               rc = lfsck_layout_extend_lovea(env, th, pobj, cfid, ea_buf,
-                                              LU_XATTR_CREATE, ltd->ltd_index,
-                                              ea_off, false);
+               rc = lfsck_layout_extend_lovea(env, lfsck, th, pobj, cfid,
+                                              &lov_buf, LU_XATTR_CREATE,
+                                              ltd->ltd_index, ea_off, false);
        dt_write_unlock(env, pobj);
        if (rc < 0)
                GOTO(stop, rc);
 
        /* 4b. Insert the MDT-object to .lustre/lost+found/MDTxxxx/ */
-       rc = dt_insert(env, lfsck->li_lpf_obj,
-                      (const struct dt_rec *)pfid,
+       rc = dt_insert(env, lfsck->li_lpf_obj, (const struct dt_rec *)dtrec,
                       (const struct dt_key *)name, th, BYPASS_CAPA, 1);
+       if (rc != 0)
+               GOTO(stop, rc);
+
+       /* 5b. insert linkEA for parent. */
+       rc = dt_xattr_set(env, pobj, &linkea_buf,
+                         XATTR_NAME_LINK, 0, th, BYPASS_CAPA);
 
        GOTO(stop, rc);
 
@@ -2050,7 +2164,15 @@ put:
                lu_object_put(env, &cobj->do_lu);
        if (pobj != NULL && !IS_ERR(pobj))
                lu_object_put(env, &pobj->do_lu);
-       ea_buf->lb_len = buflen;
+
+log:
+       if (rc < 0)
+               CDEBUG(D_LFSCK, "%s layout LFSCK assistant failed to "
+                      "recreate the lost MDT-object: parent "DFID
+                      ", child "DFID", OST-index %u, stripe-index %u, "
+                      "infix %s, type %s: rc = %d\n",
+                      lfsck_lfsck2name(lfsck), PFID(pfid), PFID(cfid),
+                      ltd->ltd_index, ea_off, infix, type, rc);
 
        return rc >= 0 ? 1 : rc;
 }
@@ -2091,7 +2213,7 @@ static int lfsck_layout_master_conditional_destroy(const struct lu_env *env,
 
        memset(lr, 0, sizeof(*lr));
        lr->lr_event = LE_CONDITIONAL_DESTROY;
-       lr->lr_active = LT_LAYOUT;
+       lr->lr_active = LFSCK_TYPE_LAYOUT;
        lr->lr_fid = *fid;
 
        tmp = req_capsule_client_get(&req->rq_pill, &RMF_LFSCK_REQUEST);
@@ -2132,7 +2254,8 @@ static int lfsck_layout_slave_conditional_destroy(const struct lu_env *env,
                RETURN(PTR_ERR(obj));
 
        dt_read_lock(env, obj, 0);
-       if (dt_object_exists(obj) == 0) {
+       if (dt_object_exists(obj) == 0 ||
+           lfsck_is_dead_obj(obj)) {
                dt_read_unlock(env, obj);
 
                GOTO(put, rc = -ENOENT);
@@ -2191,10 +2314,11 @@ static int lfsck_layout_slave_conditional_destroy(const struct lu_env *env,
 
        rc = dt_destroy(env, obj, th);
        if (rc == 0)
-               CDEBUG(D_LFSCK, "Destroy the empty OST-object "DFID" which "
-                      "was created for reparing dangling referenced case. "
-                      "But the original missed OST-object is found now.\n",
-                      PFID(fid));
+               CDEBUG(D_LFSCK, "%s: layout LFSCK destroyed the empty "
+                      "OST-object "DFID" that was created for reparing "
+                      "dangling referenced case. But the original missed "
+                      "OST-object is found now.\n",
+                      lfsck_lfsck2name(lfsck), PFID(fid));
 
        GOTO(stop, rc);
 
@@ -2232,12 +2356,12 @@ static int lfsck_layout_conflict_create(const struct lu_env *env,
                                        struct lu_fid *cfid,
                                        struct lu_buf *ea_buf,
                                        struct lov_ost_data_v1 *slot,
-                                       __u32 ea_off, __u32 ori_len)
+                                       __u32 ea_off)
 {
        struct lfsck_thread_info *info          = lfsck_env_info(env);
        struct lu_fid            *cfid2         = &info->lti_fid2;
        struct ost_id            *oi            = &info->lti_oi;
-       char                     *postfix       = info->lti_tmpbuf;
+       char                     *infix         = info->lti_tmpbuf;
        struct lov_mds_md_v1     *lmm           = ea_buf->lb_buf;
        struct dt_device         *dev           = com->lc_lfsck->li_bottom;
        struct thandle           *th            = NULL;
@@ -2247,13 +2371,9 @@ static int lfsck_layout_conflict_create(const struct lu_env *env,
        ENTRY;
 
        ostid_le_to_cpu(&slot->l_ost_oi, oi);
-       ostid_to_fid(cfid2, oi, ost_idx2);
-
-       CDEBUG(D_LFSCK, "Handle layout EA conflict: parent "DFID
-              ", cur-child "DFID" on the OST %u, orphan-child "
-              DFID" on the OST %u, stripe-index %u\n",
-              PFID(lfsck_dto2fid(parent)), PFID(cfid2), ost_idx2,
-              PFID(cfid), ltd->ltd_index, ea_off);
+       rc = ostid_to_fid(cfid2, oi, ost_idx2);
+       if (rc != 0)
+               GOTO(out, rc);
 
        /* Hold layout lock on the parent to prevent others to access. */
        rc = lfsck_layout_lock(env, com, parent, &lh,
@@ -2270,13 +2390,12 @@ static int lfsck_layout_conflict_create(const struct lu_env *env,
        if (rc == -ETXTBSY) {
                /* No need the layout lock on the original parent. */
                lfsck_layout_unlock(&lh);
-               ea_buf->lb_len = ori_len;
 
                fid_zero(&rec->lor_fid);
-               snprintf(postfix, LFSCK_TMPBUF_LEN, "-"DFID"-%x",
+               snprintf(infix, LFSCK_TMPBUF_LEN, "-"DFID"-%x",
                         PFID(lu_object_fid(&parent->do_lu)), ea_off);
                rc = lfsck_layout_recreate_parent(env, com, ltd, rec, cfid,
-                                                 "C-", postfix, ea_off);
+                                                 infix, "C", ea_off);
 
                RETURN(rc);
        }
@@ -2312,7 +2431,12 @@ unlock:
        lfsck_layout_unlock(&lh);
 
 out:
-       ea_buf->lb_len = ori_len;
+       CDEBUG(D_LFSCK, "%s: layout LFSCK assistant replaced the conflict "
+              "OST-object "DFID" on the OST %x with the orphan "DFID" on "
+              "the OST %x: parent "DFID", stripe-index %u: rc = %d\n",
+              lfsck_lfsck2name(com->lc_lfsck), PFID(cfid2), ost_idx2,
+              PFID(cfid), ltd->ltd_index, PFID(lfsck_dto2fid(parent)),
+              ea_off, rc);
 
        return rc >= 0 ? 1 : rc;
 }
@@ -2338,7 +2462,7 @@ static int lfsck_layout_recreate_lovea(const struct lu_env *env,
        struct dt_device         *dt            = lfsck->li_bottom;
        struct lfsck_bookmark    *bk            = &lfsck->li_bookmark_ram;
        struct thandle            *handle       = NULL;
-       size_t                    buflen        = buf->lb_len;
+       size_t                    lovea_size;
        struct lov_mds_md_v1     *lmm;
        struct lov_ost_data_v1   *objs;
        struct lustre_handle      lh            = { 0 };
@@ -2351,14 +2475,17 @@ static int lfsck_layout_recreate_lovea(const struct lu_env *env,
        bool                      locked        = false;
        ENTRY;
 
-       CDEBUG(D_LFSCK, "Re-create the crashed layout EA: parent "
-              DFID", child "DFID", OST-index %u, stripe-index %u\n",
-              PFID(lfsck_dto2fid(parent)), PFID(cfid), ost_idx, ea_off);
-
        rc = lfsck_layout_lock(env, com, parent, &lh,
                               MDS_INODELOCK_LAYOUT | MDS_INODELOCK_XATTR);
-       if (rc != 0)
+       if (rc != 0) {
+               CDEBUG(D_LFSCK, "%s: layout LFSCK assistant failed to recreate "
+                      "LOV EA for "DFID": parent "DFID", OST-index %u, "
+                      "stripe-index %u: rc = %d\n",
+                      lfsck_lfsck2name(lfsck), PFID(cfid),
+                      PFID(lfsck_dto2fid(parent)), ost_idx, ea_off, rc);
+
                RETURN(rc);
+       }
 
 again:
        if (locked) {
@@ -2374,9 +2501,9 @@ again:
        if (rc < 0)
                GOTO(unlock_layout, rc);
 
-       if (buf->lb_len < rc) {
-               lu_buf_realloc(buf, rc);
-               buflen = buf->lb_len;
+       lovea_size = rc;
+       if (buf->lb_len < lovea_size) {
+               lu_buf_realloc(buf, lovea_size);
                if (buf->lb_buf == NULL)
                        GOTO(unlock_layout, rc = -ENOMEM);
        }
@@ -2405,11 +2532,12 @@ again:
                LASSERT(rc != 0);
                goto again;
        } else if (rc == -ENODATA || rc == 0) {
-               rc = lov_mds_md_size(ea_off + 1, LOV_MAGIC_V1);
+               lovea_size = lov_mds_md_size(ea_off + 1, LOV_MAGIC_V1);
                /* If the declared is not big enough, re-try. */
-               if (buf->lb_len < rc)
+               if (buf->lb_len < lovea_size) {
+                       rc = lovea_size;
                        goto again;
-
+               }
                fl = LU_XATTR_CREATE;
        } else if (rc < 0) {
                GOTO(unlock_parent, rc);
@@ -2417,17 +2545,17 @@ again:
                goto again;
        } else {
                fl = LU_XATTR_REPLACE;
+               lovea_size = rc;
        }
 
        if (fl == LU_XATTR_CREATE) {
                if (bk->lb_param & LPF_DRYRUN)
                        GOTO(unlock_parent, rc = 1);
 
-               LASSERT(buf->lb_len >= rc);
+               LASSERT(buf->lb_len >= lovea_size);
 
-               buf->lb_len = rc;
-               rc = lfsck_layout_extend_lovea(env, handle, parent, cfid, buf,
-                                              fl, ost_idx, ea_off, false);
+               rc = lfsck_layout_extend_lovea(env, lfsck, handle, parent, cfid,
+                                              buf, fl, ost_idx, ea_off, false);
 
                GOTO(unlock_parent, rc);
        }
@@ -2440,12 +2568,10 @@ again:
                if (bk->lb_param & LPF_DRYRUN)
                        GOTO(unlock_parent, rc = 1);
 
-               LASSERT(buf->lb_len >= rc);
+               LASSERT(buf->lb_len >= lovea_size);
 
-               buf->lb_len = rc;
-               memset(lmm, 0, buf->lb_len);
-               rc = lfsck_layout_extend_lovea(env, handle, parent, cfid, buf,
-                                              fl, ost_idx, ea_off, true);
+               rc = lfsck_layout_extend_lovea(env, lfsck, handle, parent, cfid,
+                                              buf, fl, ost_idx, ea_off, true);
 
                GOTO(unlock_parent, rc);
        }
@@ -2460,7 +2586,7 @@ again:
         * be updated also. */
        magic = le32_to_cpu(lmm->lmm_magic);
        if (magic == LOV_MAGIC_V1) {
-               objs = &(lmm->lmm_objects[0]);
+               objs = &lmm->lmm_objects[0];
        } else {
                LASSERT(magic == LOV_MAGIC_V3);
                objs = &((struct lov_mds_md_v3 *)lmm)->lmm_objects[0];
@@ -2476,24 +2602,25 @@ again:
                if (bk->lb_param & LPF_DRYRUN)
                        GOTO(unlock_parent, rc = 1);
 
-               rc = lov_mds_md_size(ea_off + 1, magic);
+               lovea_size = lov_mds_md_size(ea_off + 1, magic);
                /* If the declared is not big enough, re-try. */
-               if (buf->lb_len < rc)
+               if (buf->lb_len < lovea_size) {
+                       rc = lovea_size;
                        goto again;
+               }
+
+               rc = lfsck_layout_extend_lovea(env, lfsck, handle, parent, cfid,
+                                              buf, fl, ost_idx, ea_off, false);
 
-               buf->lb_len = rc;
-               rc = lfsck_layout_extend_lovea(env, handle, parent, cfid, buf,
-                                              fl, ost_idx, ea_off, false);
                GOTO(unlock_parent, rc);
        }
 
        LASSERTF(rc > 0, "invalid rc = %d\n", rc);
 
-       buf->lb_len = rc;
        for (i = 0; i < count; i++, objs++) {
                /* The MDT-object was created via lfsck_layout_recover_create()
                 * by others before, and we fill the dummy layout EA. */
-               if (is_dummy_lov_ost_data(objs)) {
+               if (lovea_slot_is_dummy(objs)) {
                        if (i != ea_off)
                                continue;
 
@@ -2505,11 +2632,28 @@ again:
                        rc = lfsck_layout_refill_lovea(env, handle, parent,
                                                       cfid, buf, objs, fl,
                                                       ost_idx);
+
+                       CDEBUG(D_LFSCK, "%s layout LFSCK assistant fill "
+                              "dummy layout slot for "DFID": parent "DFID
+                              ", OST-index %u, stripe-index %u: rc = %d\n",
+                              lfsck_lfsck2name(lfsck), PFID(cfid),
+                              PFID(lfsck_dto2fid(parent)), ost_idx, i, rc);
+
                        GOTO(unlock_parent, rc);
                }
 
                ostid_le_to_cpu(&objs->l_ost_oi, oi);
-               ostid_to_fid(fid, oi, le32_to_cpu(objs->l_ost_idx));
+               rc = ostid_to_fid(fid, oi, le32_to_cpu(objs->l_ost_idx));
+               if (rc != 0) {
+                       CDEBUG(D_LFSCK, "%s: the parent "DFID" contains "
+                              "invalid layout EA at the slot %d, index %u\n",
+                              lfsck_lfsck2name(lfsck),
+                              PFID(lfsck_dto2fid(parent)), i,
+                              le32_to_cpu(objs->l_ost_idx));
+
+                       GOTO(unlock_parent, rc);
+               }
+
                /* It should be rare case, the slot is there, but the LFSCK
                 * does not handle it during the first-phase cycle scanning. */
                if (unlikely(lu_fid_eq(fid, cfid))) {
@@ -2526,10 +2670,17 @@ again:
                                if (handle != NULL)
                                        dt_trans_stop(env, dt, handle);
                                lfsck_layout_unlock(&lh);
-                               buf->lb_len = buflen;
                                rc = lfsck_layout_update_pfid(env, com, parent,
                                                        cfid, ltd->ltd_tgt, i);
 
+                               CDEBUG(D_LFSCK, "%s layout LFSCK assistant "
+                                      "updated OST-object's pfid for "DFID
+                                      ": parent "DFID", OST-index %u, "
+                                      "stripe-index %u: rc = %d\n",
+                                      lfsck_lfsck2name(lfsck), PFID(cfid),
+                                      PFID(lfsck_dto2fid(parent)),
+                                      ltd->ltd_index, i, rc);
+
                                RETURN(rc);
                        }
                }
@@ -2545,11 +2696,11 @@ again:
                dt_trans_stop(env, dt, handle);
        lfsck_layout_unlock(&lh);
        if (le32_to_cpu(lmm->lmm_magic) == LOV_MAGIC_V1)
-               objs = &(lmm->lmm_objects[ea_off]);
+               objs = &lmm->lmm_objects[ea_off];
        else
                objs = &((struct lov_mds_md_v3 *)lmm)->lmm_objects[ea_off];
        rc = lfsck_layout_conflict_create(env, com, ltd, rec, parent, cfid,
-                                         buf, objs, ea_off, buflen);
+                                         buf, objs, ea_off);
 
        RETURN(rc);
 
@@ -2563,7 +2714,6 @@ stop:
 
 unlock_layout:
        lfsck_layout_unlock(&lh);
-       buf->lb_len = buflen;
 
        return rc;
 }
@@ -2586,7 +2736,7 @@ static int lfsck_layout_scan_orphan_one(const struct lu_env *env,
 
        if (fid_is_zero(pfid)) {
                rc = lfsck_layout_recreate_parent(env, com, ltd, rec, cfid,
-                                                 "N-", "", ea_off);
+                                                 "", "N", ea_off);
                GOTO(out, rc);
        }
 
@@ -2604,7 +2754,7 @@ static int lfsck_layout_scan_orphan_one(const struct lu_env *env,
        if (dt_object_exists(parent) == 0) {
                lu_object_put(env, &parent->do_lu);
                rc = lfsck_layout_recreate_parent(env, com, ltd, rec, cfid,
-                                                 "R-", "", ea_off);
+                                                 "", "R", ea_off);
                GOTO(out, rc);
        }
 
@@ -2654,15 +2804,19 @@ static int lfsck_layout_scan_orphan(const struct lu_env *env,
        int                              rc     = 0;
        ENTRY;
 
-       CDEBUG(D_LFSCK, "%s: start the orphan scanning for OST%04x\n",
+       CDEBUG(D_LFSCK, "%s: layout LFSCK assistant starts the orphan "
+              "scanning for OST%04x\n",
               lfsck_lfsck2name(lfsck), ltd->ltd_index);
 
        ostid_set_seq(oi, FID_SEQ_IDIF);
        ostid_set_id(oi, 0);
-       ostid_to_fid(fid, oi, ltd->ltd_index);
+       rc = ostid_to_fid(fid, oi, ltd->ltd_index);
+       if (rc != 0)
+               GOTO(log, rc);
+
        obj = lfsck_object_find_by_dev(env, ltd->ltd_tgt, fid);
        if (unlikely(IS_ERR(obj)))
-               RETURN(PTR_ERR(obj));
+               GOTO(log, rc = PTR_ERR(obj));
 
        rc = obj->do_ops->do_index_try(env, obj, &dt_lfsck_orphan_features);
        if (rc != 0)
@@ -2731,7 +2885,9 @@ fini:
 put:
        lu_object_put(env, &obj->do_lu);
 
-       CDEBUG(D_LFSCK, "%s: finish the orphan scanning for OST%04x, rc = %d\n",
+log:
+       CDEBUG(D_LFSCK, "%s: layout LFSCK assistant finished the orphan "
+              "scanning for OST%04x: rc = %d\n",
               lfsck_lfsck2name(lfsck), ltd->ltd_index, rc);
 
        return rc > 0 ? 0 : rc;
@@ -2771,15 +2927,8 @@ static int lfsck_layout_repair_dangling(const struct lu_env *env,
        else
                create = false;
 
-       CDEBUG(D_LFSCK, "Found dangling reference for: parent "DFID
-              ", child "DFID", OST-index %u, stripe-index %u, owner %u:%u. %s",
-              PFID(lfsck_dto2fid(parent)), PFID(lfsck_dto2fid(child)),
-              llr->llr_ost_idx, llr->llr_lov_idx, pla->la_uid, pla->la_gid,
-              create ? "Create the lost OST-object as required.\n" :
-                       "Keep the MDT-object there by default.\n");
-
        if (!create)
-               RETURN(1);
+               GOTO(log, rc = 1);
 
        memset(cla, 0, sizeof(*cla));
        cla->la_uid = pla->la_uid;
@@ -2791,7 +2940,7 @@ static int lfsck_layout_repair_dangling(const struct lu_env *env,
        rc = lfsck_layout_lock(env, com, parent, &lh,
                               MDS_INODELOCK_LAYOUT | MDS_INODELOCK_XATTR);
        if (rc != 0)
-               RETURN(rc);
+               GOTO(log, rc);
 
        handle = dt_trans_create(env, dev);
        if (IS_ERR(handle))
@@ -2821,7 +2970,7 @@ static int lfsck_layout_repair_dangling(const struct lu_env *env,
                GOTO(stop, rc);
 
        dt_read_lock(env, parent, 0);
-       if (unlikely(lu_object_is_dying(parent->do_lu.lo_header)))
+       if (unlikely(lfsck_is_dead_obj(parent)))
                GOTO(unlock2, rc = 1);
 
        rc = dt_create(env, child, cla, hint, NULL, handle);
@@ -2842,6 +2991,16 @@ stop:
 unlock1:
        lfsck_layout_unlock(&lh);
 
+log:
+       CDEBUG(D_LFSCK, "%s: layout LFSCK assistant found dangling "
+              "reference for: parent "DFID", child "DFID", OST-index %u, "
+              "stripe-index %u, owner %u/%u. %s: rc = %d\n",
+              lfsck_lfsck2name(com->lc_lfsck), PFID(lfsck_dto2fid(parent)),
+              PFID(lfsck_dto2fid(child)), llr->llr_ost_idx,
+              llr->llr_lov_idx, pla->la_uid, pla->la_gid,
+              create ? "Create the lost OST-object as required" :
+                       "Keep the MDT-object there by default", rc);
+
        return rc;
 }
 
@@ -2866,15 +3025,10 @@ static int lfsck_layout_repair_unmatched_pair(const struct lu_env *env,
        int                              rc;
        ENTRY;
 
-       CDEBUG(D_LFSCK, "Repair unmatched MDT-OST pair for: parent "DFID
-              ", child "DFID", OST-index %u, stripe-index %u, owner %u:%u\n",
-              PFID(lfsck_dto2fid(parent)), PFID(lfsck_dto2fid(child)),
-              llr->llr_ost_idx, llr->llr_lov_idx, pla->la_uid, pla->la_gid);
-
        rc = lfsck_layout_lock(env, com, parent, &lh,
                               MDS_INODELOCK_LAYOUT | MDS_INODELOCK_XATTR);
        if (rc != 0)
-               RETURN(rc);
+               GOTO(log, rc);
 
        handle = dt_trans_create(env, dev);
        if (IS_ERR(handle))
@@ -2904,7 +3058,7 @@ static int lfsck_layout_repair_unmatched_pair(const struct lu_env *env,
                GOTO(stop, rc);
 
        dt_write_lock(env, parent, 0);
-       if (unlikely(lu_object_is_dying(parent->do_lu.lo_header)))
+       if (unlikely(lfsck_is_dead_obj(parent)))
                GOTO(unlock2, rc = 1);
 
        rc = dt_xattr_set(env, child, buf, XATTR_NAME_FID, 0, handle,
@@ -2931,6 +3085,14 @@ stop:
 unlock1:
        lfsck_layout_unlock(&lh);
 
+log:
+       CDEBUG(D_LFSCK, "%s: layout LFSCK assistant repaired unmatched "
+              "MDT-OST pair for: parent "DFID", child "DFID", OST-index %u, "
+              "stripe-index %u, owner %u/%u: rc = %d\n",
+              lfsck_lfsck2name(com->lc_lfsck), PFID(lfsck_dto2fid(parent)),
+              PFID(lfsck_dto2fid(child)), llr->llr_ost_idx, llr->llr_lov_idx,
+              pla->la_uid, pla->la_gid, rc);
+
        return rc;
 }
 
@@ -2957,19 +3119,15 @@ static int lfsck_layout_repair_multiple_references(const struct lu_env *env,
        struct lov_mds_md_v1            *lmm;
        struct lov_ost_data_v1          *objs;
        struct lustre_handle             lh     = { 0 };
+       struct lu_buf                    ea_buf;
        __u32                            magic;
        int                              rc;
        ENTRY;
 
-       CDEBUG(D_LFSCK, "Repair multiple references for: parent "DFID
-              ", OST-index %u, stripe-index %u, owner %u:%u\n",
-              PFID(lfsck_dto2fid(parent)), llr->llr_ost_idx,
-              llr->llr_lov_idx, la->la_uid, la->la_gid);
-
        rc = lfsck_layout_lock(env, com, parent, &lh,
                               MDS_INODELOCK_LAYOUT | MDS_INODELOCK_XATTR);
        if (rc != 0)
-               RETURN(rc);
+               GOTO(log, rc);
 
        handle = dt_trans_create(env, pdev);
        if (IS_ERR(handle))
@@ -3003,7 +3161,7 @@ static int lfsck_layout_repair_multiple_references(const struct lu_env *env,
                GOTO(stop, rc);
 
        dt_write_lock(env, parent, 0);
-       if (unlikely(lu_object_is_dying(parent->do_lu.lo_header)))
+       if (unlikely(lfsck_is_dead_obj(parent)))
                GOTO(unlock2, rc = 0);
 
        rc = dt_xattr_get(env, parent, buf, XATTR_NAME_LOV, BYPASS_CAPA);
@@ -3025,7 +3183,7 @@ static int lfsck_layout_repair_multiple_references(const struct lu_env *env,
         * be updated also. */
        magic = le32_to_cpu(lmm->lmm_magic);
        if (magic == LOV_MAGIC_V1) {
-               objs = &(lmm->lmm_objects[0]);
+               objs = &lmm->lmm_objects[0];
        } else {
                LASSERT(magic == LOV_MAGIC_V3);
                objs = &((struct lov_mds_md_v3 *)lmm)->lmm_objects[0];
@@ -3036,7 +3194,10 @@ static int lfsck_layout_repair_multiple_references(const struct lu_env *env,
        ostid_cpu_to_le(oi, &objs[llr->llr_lov_idx].l_ost_oi);
        objs[llr->llr_lov_idx].l_ost_gen = cpu_to_le32(0);
        objs[llr->llr_lov_idx].l_ost_idx = cpu_to_le32(llr->llr_ost_idx);
-       rc = dt_xattr_set(env, parent, buf, XATTR_NAME_LOV,
+       lfsck_buf_init(&ea_buf, lmm,
+                      lov_mds_md_size(le16_to_cpu(lmm->lmm_stripe_count),
+                                      magic));
+       rc = dt_xattr_set(env, parent, &ea_buf, XATTR_NAME_LOV,
                          LU_XATTR_REPLACE, handle, BYPASS_CAPA);
 
        GOTO(unlock2, rc = (rc == 0 ? 1 : rc));
@@ -3053,6 +3214,13 @@ stop:
 unlock1:
        lfsck_layout_unlock(&lh);
 
+log:
+       CDEBUG(D_LFSCK, "%s: layout LFSCK assistant repaired multiple "
+              "references for: parent "DFID", OST-index %u, stripe-index %u, "
+              "owner %u/%u: rc = %d\n",
+              lfsck_lfsck2name(com->lc_lfsck), PFID(lfsck_dto2fid(parent)),
+              llr->llr_ost_idx, llr->llr_lov_idx, la->la_uid, la->la_gid, rc);
+
        return rc;
 }
 
@@ -3074,14 +3242,9 @@ static int lfsck_layout_repair_owner(const struct lu_env *env,
        int                              rc;
        ENTRY;
 
-       CDEBUG(D_LFSCK, "Repair inconsistent file owner for: parent "DFID
-              ", child "DFID", OST-index %u, stripe-index %u, owner %u:%u\n",
-              PFID(lfsck_dto2fid(parent)), PFID(lfsck_dto2fid(child)),
-              llr->llr_ost_idx, llr->llr_lov_idx, pla->la_uid, pla->la_gid);
-
        handle = dt_trans_create(env, dev);
        if (IS_ERR(handle))
-               RETURN(PTR_ERR(handle));
+               GOTO(log, rc = PTR_ERR(handle));
 
        tla->la_uid = pla->la_uid;
        tla->la_gid = pla->la_gid;
@@ -3096,19 +3259,13 @@ static int lfsck_layout_repair_owner(const struct lu_env *env,
 
        /* Use the dt_object lock to serialize with destroy and attr_set. */
        dt_read_lock(env, parent, 0);
-       if (unlikely(lu_object_is_dying(parent->do_lu.lo_header)))
+       if (unlikely(lfsck_is_dead_obj(parent)))
                GOTO(unlock, rc = 1);
 
        /* Get the latest parent's owner. */
        rc = dt_attr_get(env, parent, tla, BYPASS_CAPA);
-       if (rc != 0) {
-               CWARN("%s: fail to get the latest parent's ("DFID") owner, "
-                     "not sure whether some others chown/chgrp during the "
-                     "LFSCK: rc = %d\n", lfsck_lfsck2name(com->lc_lfsck),
-                     PFID(lfsck_dto2fid(parent)), rc);
-
+       if (rc != 0)
                GOTO(unlock, rc);
-       }
 
        /* Some others chown/chgrp during the LFSCK, needs to do nothing. */
        if (unlikely(tla->la_uid != pla->la_uid ||
@@ -3126,6 +3283,14 @@ unlock:
 stop:
        rc = lfsck_layout_trans_stop(env, dev, handle, rc);
 
+log:
+       CDEBUG(D_LFSCK, "%s: layout LFSCK assistant repaired inconsistent "
+              "file owner for: parent "DFID", child "DFID", OST-index %u, "
+              "stripe-index %u, owner %u/%u: rc = %d\n",
+              lfsck_lfsck2name(com->lc_lfsck), PFID(lfsck_dto2fid(parent)),
+              PFID(lfsck_dto2fid(child)), llr->llr_ost_idx, llr->llr_lov_idx,
+              pla->la_uid, pla->la_gid, rc);
+
        return rc;
 }
 
@@ -3176,21 +3341,23 @@ static int lfsck_layout_check_parent(const struct lu_env *env,
        }
 
        tobj = lfsck_object_find(env, com->lc_lfsck, pfid);
-       if (tobj == NULL)
-               RETURN(LLIT_UNMATCHED_PAIR);
-
        if (IS_ERR(tobj))
                RETURN(PTR_ERR(tobj));
 
-       if (!dt_object_exists(tobj))
+       dt_read_lock(env, tobj, 0);
+       if (dt_object_exists(tobj) == 0 ||
+           lfsck_is_dead_obj(tobj))
+               GOTO(out, rc = LLIT_UNMATCHED_PAIR);
+
+       if (!S_ISREG(lfsck_object_type(tobj)))
                GOTO(out, rc = LLIT_UNMATCHED_PAIR);
 
        /* Load the tobj's layout EA, in spite of it is a local MDT-object or
         * remote one on another MDT. Then check whether the given OST-object
         * is in such layout. If yes, it is multiple referenced, otherwise it
         * is unmatched referenced case. */
-       rc = lfsck_layout_get_lovea(env, tobj, buf, NULL);
-       if (rc == 0)
+       rc = lfsck_layout_get_lovea(env, tobj, buf);
+       if (rc == 0 || rc == -ENOENT)
                GOTO(out, rc = LLIT_UNMATCHED_PAIR);
 
        if (rc < 0)
@@ -3199,7 +3366,7 @@ static int lfsck_layout_check_parent(const struct lu_env *env,
        lmm = buf->lb_buf;
        magic = le32_to_cpu(lmm->lmm_magic);
        if (magic == LOV_MAGIC_V1) {
-               objs = &(lmm->lmm_objects[0]);
+               objs = &lmm->lmm_objects[0];
        } else {
                LASSERT(magic == LOV_MAGIC_V3);
                objs = &((struct lov_mds_md_v3 *)lmm)->lmm_objects[0];
@@ -3209,12 +3376,23 @@ static int lfsck_layout_check_parent(const struct lu_env *env,
        for (i = 0; i < count; i++, objs++) {
                struct lu_fid           *tfid   = &info->lti_fid2;
                struct ost_id           *oi     = &info->lti_oi;
+               __u32                    idx2;
 
-               if (is_dummy_lov_ost_data(objs))
+               if (lovea_slot_is_dummy(objs))
                        continue;
 
                ostid_le_to_cpu(&objs->l_ost_oi, oi);
-               ostid_to_fid(tfid, oi, le32_to_cpu(objs->l_ost_idx));
+               idx2 = le32_to_cpu(objs->l_ost_idx);
+               rc = ostid_to_fid(tfid, oi, idx2);
+               if (rc != 0) {
+                       CDEBUG(D_LFSCK, "%s: the parent "DFID" contains "
+                              "invalid layout EA at the slot %d, index %u\n",
+                              lfsck_lfsck2name(com->lc_lfsck),
+                              PFID(pfid), i, idx2);
+
+                       GOTO(out, rc = LLIT_UNMATCHED_PAIR);
+               }
+
                if (lu_fid_eq(cfid, tfid)) {
                        *lov_ea = *buf;
 
@@ -3225,6 +3403,7 @@ static int lfsck_layout_check_parent(const struct lu_env *env,
        GOTO(out, rc = LLIT_UNMATCHED_PAIR);
 
 out:
+       dt_read_unlock(env, tobj);
        lfsck_object_put(env, tobj);
 
        return rc;
@@ -3238,7 +3417,7 @@ static int lfsck_layout_assistant_handle_one(const struct lu_env *env,
        struct lfsck_thread_info             *info   = lfsck_env_info(env);
        struct filter_fid_old                *pea    = &info->lti_old_pfid;
        struct lu_fid                        *pfid   = &info->lti_fid;
-       struct lu_buf                        *buf    = NULL;
+       struct lu_buf                         buf    = { 0 };
        struct dt_object                     *parent = llr->llr_parent->llo_obj;
        struct dt_object                     *child  = llr->llr_child;
        struct lu_attr                       *pla    = &info->lti_la;
@@ -3250,17 +3429,16 @@ static int lfsck_layout_assistant_handle_one(const struct lu_env *env,
        int                                   rc;
        ENTRY;
 
-       rc = dt_attr_get(env, parent, pla, BYPASS_CAPA);
-       if (rc != 0) {
-               if (lu_object_is_dying(parent->do_lu.lo_header))
-                       RETURN(0);
+       if (unlikely(lfsck_is_dead_obj(parent)))
+               RETURN(0);
 
+       rc = dt_attr_get(env, parent, pla, BYPASS_CAPA);
+       if (rc != 0)
                GOTO(out, rc);
-       }
 
        rc = dt_attr_get(env, child, cla, BYPASS_CAPA);
        if (rc == -ENOENT) {
-               if (lu_object_is_dying(parent->do_lu.lo_header))
+               if (unlikely(lfsck_is_dead_obj(parent)))
                        RETURN(0);
 
                type = LLIT_DANGLING;
@@ -3270,8 +3448,8 @@ static int lfsck_layout_assistant_handle_one(const struct lu_env *env,
        if (rc != 0)
                GOTO(out, rc);
 
-       buf = lfsck_buf_get(env, pea, sizeof(struct filter_fid_old));
-       rc= dt_xattr_get(env, child, buf, XATTR_NAME_FID, BYPASS_CAPA);
+       lfsck_buf_init(&buf, pea, sizeof(struct filter_fid_old));
+       rc = dt_xattr_get(env, child, &buf, XATTR_NAME_FID, BYPASS_CAPA);
        if (unlikely(rc >= 0 && rc != sizeof(struct filter_fid_old) &&
                     rc != sizeof(struct filter_fid))) {
                type = LLIT_UNMATCHED_PAIR;
@@ -3294,7 +3472,7 @@ static int lfsck_layout_assistant_handle_one(const struct lu_env *env,
 
        rc = lfsck_layout_check_parent(env, com, parent, pfid,
                                       lu_object_fid(&child->do_lu),
-                                      pla, cla, llr, buf, idx);
+                                      pla, cla, llr, &buf, idx);
        if (rc > 0) {
                type = rc;
                goto repair;
@@ -3326,7 +3504,7 @@ repair:
                break;
        case LLIT_MULTIPLE_REFERENCED:
                rc = lfsck_layout_repair_multiple_references(env, com, llr,
-                                                            pla, buf);
+                                                            pla, &buf);
                break;
        case LLIT_INCONSISTENT_OWNER:
                rc = lfsck_layout_repair_owner(env, com, llr, pla);
@@ -3350,7 +3528,8 @@ out:
                           rc == -EHOSTUNREACH) {
                        /* If cannot touch the target server,
                         * mark the LFSCK as INCOMPLETE. */
-                       CERROR("%s: Fail to talk with OST %x: rc = %d.\n",
+                       CDEBUG(D_LFSCK, "%s: layout LFSCK assistant fail to "
+                              "talk with OST %x: rc = %d\n",
                               lfsck_lfsck2name(lfsck), llr->llr_ost_idx, rc);
                        lo->ll_flags |= LF_INCOMPLETE;
                        lo->ll_objs_skipped++;
@@ -3407,7 +3586,8 @@ static int lfsck_layout_assistant(void *args)
 
        rc = lfsck_layout_master_notify_others(env, com, lr);
        if (rc != 0) {
-               CERROR("%s: fail to notify others for layout start: rc = %d\n",
+               CDEBUG(D_LFSCK, "%s: layout LFSCK assistant failed to notify "
+                      "others for LFSCK start: rc = %d\n",
                       lfsck_lfsck2name(lfsck), rc);
                GOTO(fini, rc);
        }
@@ -3476,8 +3656,9 @@ static int lfsck_layout_assistant(void *args)
                        lr->lr_status = llmd->llmd_post_result;
                        rc = lfsck_layout_master_notify_others(env, com, lr);
                        if (rc != 0)
-                               CERROR("%s: failed to notify others "
-                                      "for layout post: rc = %d\n",
+                               CDEBUG(D_LFSCK, "%s: layout LFSCK assistant "
+                                      "failed to notify others for LFSCK "
+                                      "post: rc = %d\n",
                                       lfsck_lfsck2name(lfsck), rc);
 
                        /* Wakeup the master engine to go ahead. */
@@ -3490,6 +3671,9 @@ static int lfsck_layout_assistant(void *args)
                        llmd->llmd_in_double_scan = 1;
                        wake_up_all(&mthread->t_ctl_waitq);
 
+                       CDEBUG(D_LFSCK, "%s: layout LFSCK assistant phase2 "
+                              "scan start\n", lfsck_lfsck2name(lfsck));
+
                        com->lc_new_checked = 0;
                        com->lc_new_scanned = 0;
                        com->lc_time_last_checkpoint = cfs_time_current();
@@ -3497,6 +3681,9 @@ static int lfsck_layout_assistant(void *args)
                                com->lc_time_last_checkpoint +
                                cfs_time_seconds(LFSCK_CHECKPOINT_INTERVAL);
 
+                       /* flush all async updating before handling orphan. */
+                       dt_sync(env, lfsck->li_next);
+
                        while (llmd->llmd_in_double_scan) {
                                struct lfsck_tgt_descs  *ltds =
                                                        &lfsck->li_ost_descs;
@@ -3608,7 +3795,7 @@ cleanup2:
                                lr->lr_status = LS_CO_STOPPED;
                                break;
                        default:
-                               CERROR("%s: unknown status: rc = %d\n",
+                               CDEBUG(D_LFSCK, "%s: unknown status: rc = %d\n",
                                       lfsck_lfsck2name(lfsck),
                                       lfsck->li_status);
                                lr->lr_status = LS_CO_FAILED;
@@ -3627,16 +3814,28 @@ cleanup2:
 
        rc1 = lfsck_layout_master_notify_others(env, com, lr);
        if (rc1 != 0) {
-               CERROR("%s: failed to notify others for layout quit: rc = %d\n",
+               CDEBUG(D_LFSCK, "%s: layout LFSCK assistant failed to "
+                      "notify others for LFSCK quit: rc = %d\n",
                       lfsck_lfsck2name(lfsck), rc1);
                rc = rc1;
        }
 
+       /* flush all async updating before exit. */
+       dt_sync(env, lfsck->li_next);
+
        /* Under force exit case, some requests may be just freed without
         * verification, those objects should be re-handled when next run.
         * So not update the on-disk tracing file under such case. */
-       if (llmd->llmd_in_double_scan && !llmd->llmd_exit)
-               rc1 = lfsck_layout_double_scan_result(env, com, rc);
+       if (llmd->llmd_in_double_scan) {
+               struct lfsck_layout *lo = com->lc_file_ram;
+
+               if (!llmd->llmd_exit)
+                       rc1 = lfsck_layout_double_scan_result(env, com, rc);
+
+               CDEBUG(D_LFSCK, "%s: layout LFSCK assistant phase2 scan "
+                      "finished, status %d: rc = %d\n",
+                      lfsck_lfsck2name(lfsck), lo->ll_status, rc1);
+       }
 
 fini:
        if (llmd->llmd_in_double_scan)
@@ -3662,6 +3861,7 @@ lfsck_layout_slave_async_interpret(const struct lu_env *env,
        struct lfsck_component               *com   = llsaa->llsaa_com;
        struct lfsck_layout_slave_target     *llst  = llsaa->llsaa_llst;
        struct lfsck_layout_slave_data       *llsd  = com->lc_data;
+       struct lfsck_reply                   *lr    = NULL;
        bool                                  done  = false;
 
        if (rc != 0) {
@@ -3670,15 +3870,20 @@ lfsck_layout_slave_async_interpret(const struct lu_env *env,
                 * the target finished the LFSCK prcoessing. */
                done = true;
        } else {
-               struct lfsck_reply *lr;
-
                lr = req_capsule_server_get(&req->rq_pill, &RMF_LFSCK_REPLY);
                if (lr->lr_status != LS_SCANNING_PHASE1 &&
                    lr->lr_status != LS_SCANNING_PHASE2)
                        done = true;
        }
-       if (done)
+
+       if (done) {
+               CDEBUG(D_LFSCK, "%s: layout LFSCK slave gets the MDT %x "
+                      "status %d\n", lfsck_lfsck2name(com->lc_lfsck),
+                      llst->llst_index, lr != NULL ? lr->lr_status : rc);
+
                lfsck_layout_llst_del(llsd, llst);
+       }
+
        lfsck_layout_llst_put(llst);
        lfsck_component_put(env, com);
        class_export_put(exp);
@@ -3767,12 +3972,12 @@ lfsck_layout_slave_query_master(const struct lu_env *env,
 
        set = ptlrpc_prep_set();
        if (set == NULL)
-               RETURN(-ENOMEM);
+               GOTO(log, rc = -ENOMEM);
 
        memset(lr, 0, sizeof(*lr));
        lr->lr_index = lfsck_dev_idx(lfsck->li_bottom);
        lr->lr_event = LE_QUERY;
-       lr->lr_active = LT_LAYOUT;
+       lr->lr_active = LFSCK_TYPE_LAYOUT;
 
        llsd->llsd_touch_gen++;
        spin_lock(&llsd->llsd_lock);
@@ -3784,9 +3989,8 @@ lfsck_layout_slave_query_master(const struct lu_env *env,
                        break;
 
                llst->llst_gen = llsd->llsd_touch_gen;
-               list_del(&llst->llst_list);
-               list_add_tail(&llst->llst_list,
-                             &llsd->llsd_master_list);
+               list_move_tail(&llst->llst_list,
+                              &llsd->llsd_master_list);
                atomic_inc(&llst->llst_ref);
                spin_unlock(&llsd->llsd_lock);
 
@@ -3801,9 +4005,11 @@ lfsck_layout_slave_query_master(const struct lu_env *env,
 
                rc = lfsck_layout_async_query(env, com, exp, llst, lr, set);
                if (rc != 0) {
-                       CERROR("%s: slave fail to query %s for layout: "
-                              "rc = %d\n", lfsck_lfsck2name(lfsck),
+                       CDEBUG(D_LFSCK, "%s: layout LFSCK slave fail to "
+                              "query %s for layout: rc = %d\n",
+                              lfsck_lfsck2name(lfsck),
                               exp->exp_obd->obd_name, rc);
+
                        rc1 = rc;
                        lfsck_layout_llst_put(llst);
                        class_export_put(exp);
@@ -3815,7 +4021,13 @@ lfsck_layout_slave_query_master(const struct lu_env *env,
        rc = ptlrpc_set_wait(set);
        ptlrpc_set_destroy(set);
 
-       RETURN(rc1 != 0 ? rc1 : rc);
+       GOTO(log, rc = (rc1 != 0 ? rc1 : rc));
+
+log:
+       CDEBUG(D_LFSCK, "%s: layout LFSCK slave queries master: rc = %d\n",
+              lfsck_lfsck2name(com->lc_lfsck), rc);
+
+       return rc;
 }
 
 static void
@@ -3832,6 +4044,9 @@ lfsck_layout_slave_notify_master(const struct lu_env *env,
        int                               rc;
        ENTRY;
 
+       CDEBUG(D_LFSCK, "%s: layout LFSCK slave notifies master\n",
+              lfsck_lfsck2name(com->lc_lfsck));
+
        set = ptlrpc_prep_set();
        if (set == NULL)
                RETURN_EXIT;
@@ -3841,7 +4056,7 @@ lfsck_layout_slave_notify_master(const struct lu_env *env,
        lr->lr_flags = LEF_FROM_OST;
        lr->lr_status = result;
        lr->lr_index = lfsck_dev_idx(lfsck->li_bottom);
-       lr->lr_active = LT_LAYOUT;
+       lr->lr_active = LFSCK_TYPE_LAYOUT;
        llsd->llsd_touch_gen++;
        spin_lock(&llsd->llsd_lock);
        while (!list_empty(&llsd->llsd_master_list)) {
@@ -3852,9 +4067,8 @@ lfsck_layout_slave_notify_master(const struct lu_env *env,
                        break;
 
                llst->llst_gen = llsd->llsd_touch_gen;
-               list_del(&llst->llst_list);
-               list_add_tail(&llst->llst_list,
-                             &llsd->llsd_master_list);
+               list_move_tail(&llst->llst_list,
+                              &llsd->llsd_master_list);
                atomic_inc(&llst->llst_ref);
                spin_unlock(&llsd->llsd_lock);
 
@@ -3869,9 +4083,11 @@ lfsck_layout_slave_notify_master(const struct lu_env *env,
 
                rc = lfsck_layout_async_notify(env, exp, lr, set);
                if (rc != 0)
-                       CERROR("%s: slave fail to notify %s for layout: "
-                              "rc = %d\n", lfsck_lfsck2name(lfsck),
+                       CDEBUG(D_LFSCK, "%s: layout LFSCK slave fail to "
+                              "notify %s for layout: rc = %d\n",
+                              lfsck_lfsck2name(lfsck),
                               exp->exp_obd->obd_name, rc);
+
                lfsck_layout_llst_put(llst);
                class_export_put(exp);
                spin_lock(&llsd->llsd_lock);
@@ -3913,10 +4129,14 @@ static int lfsck_layout_master_check_pairs(const struct lu_env *env,
                RETURN(PTR_ERR(obj));
 
        dt_read_lock(env, obj, 0);
-       if (unlikely(!dt_object_exists(obj)))
+       if (unlikely(dt_object_exists(obj) == 0 ||
+                    lfsck_is_dead_obj(obj)))
                GOTO(unlock, rc = -ENOENT);
 
-       rc = lfsck_layout_get_lovea(env, obj, buf, NULL);
+       if (!S_ISREG(lfsck_object_type(obj)))
+               GOTO(unlock, rc = -ENODATA);
+
+       rc = lfsck_layout_get_lovea(env, obj, buf);
        if (rc < 0)
                GOTO(unlock, rc);
 
@@ -3934,7 +4154,7 @@ static int lfsck_layout_master_check_pairs(const struct lu_env *env,
         * be updated also. */
        magic = le32_to_cpu(lmm->lmm_magic);
        if (magic == LOV_MAGIC_V1) {
-               objs = &(lmm->lmm_objects[0]);
+               objs = &lmm->lmm_objects[0];
        } else {
                LASSERT(magic == LOV_MAGIC_V3);
                objs = &((struct lov_mds_md_v3 *)lmm)->lmm_objects[0];
@@ -4018,7 +4238,7 @@ static int lfsck_layout_slave_check_pairs(const struct lu_env *env,
        lr = req_capsule_client_get(&req->rq_pill, &RMF_LFSCK_REQUEST);
        memset(lr, 0, sizeof(*lr));
        lr->lr_event = LE_PAIRS_VERIFY;
-       lr->lr_active = LT_LAYOUT;
+       lr->lr_active = LFSCK_TYPE_LAYOUT;
        lr->lr_fid = *cfid; /* OST-object itself FID. */
        lr->lr_fid2 = *pfid; /* The claimed parent FID. */
 
@@ -4053,12 +4273,13 @@ static int lfsck_layout_slave_repair_pfid(const struct lu_env *env,
 
        obj = lfsck_object_find_by_dev(env, dev, &lr->lr_fid);
        if (IS_ERR(obj))
-               RETURN(PTR_ERR(obj));
+               GOTO(log, rc = PTR_ERR(obj));
 
        fid_cpu_to_le(&ff->ff_parent, &lr->lr_fid2);
        buf = lfsck_buf_get(env, ff, sizeof(*ff));
        dt_write_lock(env, obj, 0);
-       if (unlikely(!dt_object_exists(obj)))
+       if (unlikely(dt_object_exists(obj) == 0 ||
+                    lfsck_is_dead_obj(obj)))
                GOTO(unlock, rc = 0);
 
        th = dt_trans_create(env, dev);
@@ -4084,6 +4305,11 @@ unlock:
        dt_write_unlock(env, obj);
        lu_object_put(env, &obj->do_lu);
 
+log:
+       CDEBUG(D_LFSCK, "%s: layout LFSCK slave repaired pfid for "DFID
+              ", parent "DFID": rc = %d\n", lfsck_lfsck2name(com->lc_lfsck),
+              PFID(&lr->lr_fid), PFID(&lr->lr_fid2), rc);
+
        return rc;
 }
 
@@ -4113,6 +4339,9 @@ static int lfsck_layout_reset(const struct lu_env *env,
        rc = lfsck_layout_store(env, com);
        up_write(&com->lc_sem);
 
+       CDEBUG(D_LFSCK, "%s: layout LFSCK reset: rc = %d\n",
+              lfsck_lfsck2name(com->lc_lfsck), rc);
+
        return rc;
 }
 
@@ -4167,6 +4396,10 @@ static int lfsck_layout_master_checkpoint(const struct lu_env *env,
        rc = lfsck_layout_store(env, com);
        up_write(&com->lc_sem);
 
+       CDEBUG(D_LFSCK, "%s: layout LFSCK master checkpoint at the pos ["
+              LPU64"]: rc = %d\n", lfsck_lfsck2name(lfsck),
+              lfsck->li_pos_current.lp_oit_cookie, rc);
+
        return rc;
 }
 
@@ -4181,7 +4414,6 @@ static int lfsck_layout_slave_checkpoint(const struct lu_env *env,
                return 0;
 
        down_write(&com->lc_sem);
-
        if (init) {
                lo->ll_pos_latest_start = lfsck->li_pos_current.lp_oit_cookie;
        } else {
@@ -4195,9 +4427,12 @@ static int lfsck_layout_slave_checkpoint(const struct lu_env *env,
        }
 
        rc = lfsck_layout_store(env, com);
-
        up_write(&com->lc_sem);
 
+       CDEBUG(D_LFSCK, "%s: layout LFSCK slave checkpoint at the pos ["
+              LPU64"]: rc = %d\n", lfsck_lfsck2name(lfsck),
+              lfsck->li_pos_current.lp_oit_cookie, rc);
+
        return rc;
 }
 
@@ -4218,8 +4453,15 @@ static int lfsck_layout_prep(const struct lu_env *env,
                int rc;
 
                rc = lfsck_layout_reset(env, com, false);
-               if (rc != 0)
+               if (rc == 0)
+                       rc = lfsck_set_param(env, lfsck, start, true);
+
+               if (rc != 0) {
+                       CDEBUG(D_LFSCK, "%s: layout LFSCK prep failed: "
+                              "rc = %d\n", lfsck_lfsck2name(lfsck), rc);
+
                        return rc;
+               }
        }
 
        down_write(&com->lc_sem);
@@ -4229,9 +4471,8 @@ static int lfsck_layout_prep(const struct lu_env *env,
                if (!lfsck->li_drop_dryrun ||
                    lo->ll_pos_first_inconsistent == 0) {
                        lo->ll_status = LS_SCANNING_PHASE2;
-                       list_del_init(&com->lc_link);
-                       list_add_tail(&com->lc_link,
-                                     &lfsck->li_list_double_scan);
+                       list_move_tail(&com->lc_link,
+                                      &lfsck->li_list_double_scan);
                        pos->lp_oit_cookie = 0;
                } else {
                        int i;
@@ -4268,13 +4509,26 @@ static int lfsck_layout_slave_prep(const struct lu_env *env,
                                   struct lfsck_start_param *lsp)
 {
        struct lfsck_layout_slave_data  *llsd   = com->lc_data;
+       struct lfsck_instance           *lfsck  = com->lc_lfsck;
+       struct lfsck_layout             *lo     = com->lc_file_ram;
        struct lfsck_start              *start  = lsp->lsp_start;
        int                              rc;
 
        rc = lfsck_layout_prep(env, com, start);
-       if (rc != 0 || !lsp->lsp_index_valid)
+       if (rc != 0)
                return rc;
 
+       if (lo->ll_flags & LF_CRASHED_LASTID &&
+           list_empty(&llsd->llsd_master_list)) {
+               LASSERT(lfsck->li_out_notify != NULL);
+
+               lfsck->li_out_notify(env, lfsck->li_out_notify_data,
+                                    LE_LASTID_REBUILDING);
+       }
+
+       if (!lsp->lsp_index_valid)
+               return 0;
+
        rc = lfsck_layout_llst_add(llsd, lsp->lsp_index);
        if (rc == 0 && start != NULL && start->ls_flags & LPF_ORPHAN) {
                LASSERT(!llsd->llsd_rbtree_valid);
@@ -4284,6 +4538,10 @@ static int lfsck_layout_slave_prep(const struct lu_env *env,
                write_unlock(&llsd->llsd_rb_lock);
        }
 
+       CDEBUG(D_LFSCK, "%s: layout LFSCK slave prep done, start pos ["
+              LPU64"]\n", lfsck_lfsck2name(lfsck),
+              com->lc_pos_start.lp_oit_cookie);
+
        return rc;
 }
 
@@ -4296,7 +4554,8 @@ static int lfsck_layout_master_prep(const struct lu_env *env,
        struct ptlrpc_thread            *mthread = &lfsck->li_thread;
        struct ptlrpc_thread            *athread = &llmd->llmd_thread;
        struct lfsck_thread_args        *lta;
-       long                             rc;
+       struct task_struct              *task;
+       int                              rc;
        ENTRY;
 
        rc = lfsck_layout_prep(env, com, lsp->lsp_start);
@@ -4315,10 +4574,11 @@ static int lfsck_layout_master_prep(const struct lu_env *env,
        if (IS_ERR(lta))
                RETURN(PTR_ERR(lta));
 
-       rc = PTR_ERR(kthread_run(lfsck_layout_assistant, lta, "lfsck_layout"));
-       if (IS_ERR_VALUE(rc)) {
-               CERROR("%s: Cannot start LFSCK layout assistant thread: "
-                      "rc = %ld\n", lfsck_lfsck2name(lfsck), rc);
+       task = kthread_run(lfsck_layout_assistant, lta, "lfsck_layout");
+       if (IS_ERR(task)) {
+               rc = PTR_ERR(task);
+               CERROR("%s: cannot start LFSCK layout assistant thread: "
+                      "rc = %d\n", lfsck_lfsck2name(lfsck), rc);
                lfsck_thread_args_fini(lta);
        } else {
                struct l_wait_info lwi = { 0 };
@@ -4333,6 +4593,10 @@ static int lfsck_layout_master_prep(const struct lu_env *env,
                        rc = 0;
        }
 
+       CDEBUG(D_LFSCK, "%s: layout LFSCK master prep done, start pos ["
+              LPU64"\n", lfsck_lfsck2name(lfsck),
+              com->lc_pos_start.lp_oit_cookie);
+
        RETURN(rc);
 }
 
@@ -4353,7 +4617,7 @@ static int lfsck_layout_scan_stripes(const struct lu_env *env,
        struct ptlrpc_thread            *mthread = &lfsck->li_thread;
        struct ptlrpc_thread            *athread = &llmd->llmd_thread;
                struct l_wait_info       lwi     = { 0 };
-       struct lu_buf                   *buf;
+       struct lu_buf                    buf;
        int                              rc      = 0;
        int                              i;
        __u32                            magic;
@@ -4361,8 +4625,8 @@ static int lfsck_layout_scan_stripes(const struct lu_env *env,
        __u16                            gen;
        ENTRY;
 
-       buf = lfsck_buf_get(env, &info->lti_old_pfid,
-                           sizeof(struct filter_fid_old));
+       lfsck_buf_init(&buf, &info->lti_old_pfid,
+                      sizeof(struct filter_fid_old));
        count = le16_to_cpu(lmm->lmm_stripe_count);
        gen = le16_to_cpu(lmm->lmm_layout_gen);
        /* Currently, we only support LOV_MAGIC_V1/LOV_MAGIC_V3 which has
@@ -4371,7 +4635,7 @@ static int lfsck_layout_scan_stripes(const struct lu_env *env,
         * be updated also. */
        magic = le32_to_cpu(lmm->lmm_magic);
        if (magic == LOV_MAGIC_V1) {
-               objs = &(lmm->lmm_objects[0]);
+               objs = &lmm->lmm_objects[0];
        } else {
                LASSERT(magic == LOV_MAGIC_V3);
                objs = &((struct lov_mds_md_v3 *)lmm)->lmm_objects[0];
@@ -4383,11 +4647,10 @@ static int lfsck_layout_scan_stripes(const struct lu_env *env,
                struct lfsck_layout_req *llr;
                struct lfsck_tgt_desc   *tgt    = NULL;
                struct dt_object        *cobj   = NULL;
-               __u32                    index  =
-                                       le32_to_cpu(objs->l_ost_idx);
+               __u32                    index;
                bool                     wakeup = false;
 
-               if (is_dummy_lov_ost_data(objs))
+               if (unlikely(lovea_slot_is_dummy(objs)))
                        continue;
 
                l_wait_event(mthread->t_ctl_waitq,
@@ -4401,19 +4664,66 @@ static int lfsck_layout_scan_stripes(const struct lu_env *env,
                             thread_is_stopped(athread))
                        GOTO(out, rc = 0);
 
+               if (unlikely(lfsck_is_dead_obj(parent)))
+                       GOTO(out, rc = 0);
+
                ostid_le_to_cpu(&objs->l_ost_oi, oi);
-               ostid_to_fid(fid, oi, index);
+               index = le32_to_cpu(objs->l_ost_idx);
+               rc = ostid_to_fid(fid, oi, index);
+               if (rc != 0) {
+                       CDEBUG(D_LFSCK, "%s: get invalid layout EA for "DFID
+                              ": "DOSTID", idx:%u\n", lfsck_lfsck2name(lfsck),
+                              PFID(lfsck_dto2fid(parent)), POSTID(oi), index);
+                       goto next;
+               }
+
                tgt = lfsck_tgt_get(ltds, index);
                if (unlikely(tgt == NULL)) {
-                       CERROR("%s: Cannot talk with OST %x which did not join "
-                              "the layout LFSCK.\n",
+                       CDEBUG(D_LFSCK, "%s: cannot talk with OST %x which "
+                              "did not join the layout LFSCK\n",
                               lfsck_lfsck2name(lfsck), index);
                        lo->ll_flags |= LF_INCOMPLETE;
                        goto next;
                }
 
-               cobj = lfsck_object_find_by_dev(env, tgt->ltd_tgt, fid);
+               /* There is potential deadlock race condition between object
+                * destroy and layout LFSCK. Consider the following scenario:
+                *
+                * 1) The LFSCK thread obtained the parent object firstly, at
+                *    that time, the parent object has not been destroyed yet.
+                *
+                * 2) One RPC service thread destroyed the parent and all its
+                *    children objects. Because the LFSCK is referencing the
+                *    parent object, then the parent object will be marked as
+                *    dying in RAM. On the other hand, the parent object is
+                *    referencing all its children objects, then all children
+                *    objects will be marked as dying in RAM also.
+                *
+                * 3) The LFSCK thread tries to find some child object with
+                *    the parent object referenced. Then it will find that the
+                *    child object is dying. According to the object visibility
+                *    rules: the object with dying flag cannot be returned to
+                *    others. So the LFSCK thread has to wait until the dying
+                *    object has been purged from RAM, then it can allocate a
+                *    new object (with the same FID) in RAM. Unfortunately, the
+                *    LFSCK thread itself is referencing the parent object, and
+                *    cause the parent object cannot be purged, then cause the
+                *    child object cannot be purged also. So the LFSCK thread
+                *    will fall into deadlock.
+                *
+                * We introduce non-blocked version lu_object_find() to allow
+                * the LFSCK thread to return failure immediately (instead of
+                * wait) when it finds dying (child) object, then the LFSCK
+                * thread can check whether the parent object is dying or not.
+                * So avoid above deadlock. LU-5395 */
+               cobj = lfsck_object_find_by_dev_nowait(env, tgt->ltd_tgt, fid);
                if (IS_ERR(cobj)) {
+                       if (lfsck_is_dead_obj(parent)) {
+                               lfsck_tgt_put(tgt);
+
+                               GOTO(out, rc = 0);
+                       }
+
                        rc = PTR_ERR(cobj);
                        goto next;
                }
@@ -4422,7 +4732,7 @@ static int lfsck_layout_scan_stripes(const struct lu_env *env,
                if (rc != 0)
                        goto next;
 
-               rc = dt_declare_xattr_get(env, cobj, buf, XATTR_NAME_FID,
+               rc = dt_declare_xattr_get(env, cobj, &buf, XATTR_NAME_FID,
                                          BYPASS_CAPA);
                if (rc != 0)
                        goto next;
@@ -4508,10 +4818,12 @@ static int lfsck_layout_master_exec_oit(const struct lu_env *env,
        struct lov_mds_md_v1            *lmm    = NULL;
        struct dt_device                *dev    = lfsck->li_bottom;
        struct lustre_handle             lh     = { 0 };
-       ssize_t                          buflen = buf->lb_len;
+       struct lu_buf                    ea_buf = { 0 };
        int                              rc     = 0;
+       int                              size   = 0;
        bool                             locked = false;
        bool                             stripe = false;
+       bool                             bad_oi = false;
        ENTRY;
 
        if (!S_ISREG(lfsck_object_type(obj)))
@@ -4526,11 +4838,15 @@ static int lfsck_layout_master_exec_oit(const struct lu_env *env,
        locked = true;
 
 again:
-       rc = lfsck_layout_get_lovea(env, obj, buf, &buflen);
+       if (dt_object_exists(obj) == 0 ||
+           lfsck_is_dead_obj(obj))
+               GOTO(out, rc = 0);
+
+       rc = lfsck_layout_get_lovea(env, obj, buf);
        if (rc <= 0)
                GOTO(out, rc);
 
-       buf->lb_len = rc;
+       size = rc;
        lmm = buf->lb_buf;
        rc = lfsck_layout_verify_header(lmm);
        /* If the LOV EA crashed, then it is possible to be rebuilt later
@@ -4542,8 +4858,8 @@ again:
                GOTO(out, stripe = true);
 
        /* Inconsistent lmm_oi, should be repaired. */
-       CDEBUG(D_LFSCK, "Repair bad lmm_oi for "DFID"\n",
-              PFID(lfsck_dto2fid(obj)));
+       bad_oi = true;
+       lmm->lmm_oi = *oi;
 
        if (bk->lb_param & LPF_DRYRUN) {
                down_write(&com->lc_sem);
@@ -4556,7 +4872,6 @@ again:
        if (!lustre_handle_is_used(&lh)) {
                dt_read_unlock(env, obj);
                locked = false;
-               buf->lb_len = buflen;
                rc = lfsck_layout_lock(env, com, obj, &lh,
                                       MDS_INODELOCK_LAYOUT |
                                       MDS_INODELOCK_XATTR);
@@ -4567,7 +4882,8 @@ again:
                if (IS_ERR(handle))
                        GOTO(out, rc = PTR_ERR(handle));
 
-               rc = dt_declare_xattr_set(env, obj, buf, XATTR_NAME_LOV,
+               lfsck_buf_init(&ea_buf, lmm, size);
+               rc = dt_declare_xattr_set(env, obj, &ea_buf, XATTR_NAME_LOV,
                                          LU_XATTR_REPLACE, handle);
                if (rc != 0)
                        GOTO(out, rc);
@@ -4582,8 +4898,7 @@ again:
                goto again;
        }
 
-       lmm->lmm_oi = *oi;
-       rc = dt_xattr_set(env, obj, buf, XATTR_NAME_LOV,
+       rc = dt_xattr_set(env, obj, &ea_buf, XATTR_NAME_LOV,
                          LU_XATTR_REPLACE, handle, BYPASS_CAPA);
        if (rc != 0)
                GOTO(out, rc);
@@ -4606,6 +4921,13 @@ out:
                dt_trans_stop(env, dev, handle);
 
        lfsck_layout_unlock(&lh);
+
+       if (bad_oi)
+               CDEBUG(D_LFSCK, "%s: layout LFSCK master %s bad lmm_oi for "
+                      DFID": rc = %d\n", lfsck_lfsck2name(lfsck),
+                      bk->lb_param & LPF_DRYRUN ? "found" : "repaired",
+                      PFID(lfsck_dto2fid(obj)), rc);
+
        if (stripe) {
                rc = lfsck_layout_scan_stripes(env, com, obj, lmm);
        } else {
@@ -4615,7 +4937,6 @@ out:
                        lfsck_layout_record_failure(env, lfsck, lo);
                up_write(&com->lc_sem);
        }
-       buf->lb_len = buflen;
 
        return rc;
 }
@@ -4636,6 +4957,17 @@ static int lfsck_layout_slave_exec_oit(const struct lu_env *env,
 
        LASSERT(llsd != NULL);
 
+       if (OBD_FAIL_CHECK(OBD_FAIL_LFSCK_DELAY5) &&
+           cfs_fail_val == lfsck_dev_idx(lfsck->li_bottom)) {
+               struct l_wait_info       lwi = LWI_TIMEOUT(cfs_time_seconds(1),
+                                                          NULL, NULL);
+               struct ptlrpc_thread    *thread = &lfsck->li_thread;
+
+               l_wait_event(thread->t_ctl_waitq,
+                            !thread_is_running(thread),
+                            &lwi);
+       }
+
        lfsck_rbtree_update_bitmap(env, com, fid, false);
 
        down_write(&com->lc_sem);
@@ -4658,6 +4990,9 @@ static int lfsck_layout_slave_exec_oit(const struct lu_env *env,
                lls->lls_seq = seq;
                rc = lfsck_layout_lastid_load(env, com, lls);
                if (rc != 0) {
+                       CDEBUG(D_LFSCK, "%s: layout LFSCK failed to "
+                             "load LAST_ID for "LPX64": rc = %d\n",
+                             lfsck_lfsck2name(com->lc_lfsck), seq, rc);
                        lo->ll_objs_failed_phase1++;
                        OBD_FREE_PTR(lls);
                        GOTO(unlock, rc);
@@ -4669,7 +5004,11 @@ static int lfsck_layout_slave_exec_oit(const struct lu_env *env,
        if (unlikely(fid_is_last_id(fid)))
                GOTO(unlock, rc = 0);
 
-       oid = fid_oid(fid);
+       if (fid_is_idif(fid))
+               oid = fid_idif_id(fid_seq(fid), fid_oid(fid), fid_ver(fid));
+       else
+               oid = fid_oid(fid);
+
        if (oid > lls->lls_lastid_known)
                lls->lls_lastid_known = oid;
 
@@ -4677,12 +5016,17 @@ static int lfsck_layout_slave_exec_oit(const struct lu_env *env,
                if (!(lo->ll_flags & LF_CRASHED_LASTID)) {
                        /* OFD may create new objects during LFSCK scanning. */
                        rc = lfsck_layout_lastid_reload(env, com, lls);
-                       if (unlikely(rc != 0))
-                               CWARN("%s: failed to reload LAST_ID for "LPX64
-                                     ": rc = %d\n",
+                       if (unlikely(rc != 0)) {
+                               CDEBUG(D_LFSCK, "%s: layout LFSCK failed to "
+                                     "reload LAST_ID for "LPX64": rc = %d\n",
                                      lfsck_lfsck2name(com->lc_lfsck),
                                      lls->lls_seq, rc);
-                       if (oid <= lls->lls_lastid)
+
+                               GOTO(unlock, rc);
+                       }
+
+                       if (oid <= lls->lls_lastid ||
+                           lo->ll_flags & LF_CRASHED_LASTID)
                                GOTO(unlock, rc = 0);
 
                        LASSERT(lfsck->li_out_notify != NULL);
@@ -4690,6 +5034,12 @@ static int lfsck_layout_slave_exec_oit(const struct lu_env *env,
                        lfsck->li_out_notify(env, lfsck->li_out_notify_data,
                                             LE_LASTID_REBUILDING);
                        lo->ll_flags |= LF_CRASHED_LASTID;
+
+                       CDEBUG(D_LFSCK, "%s: layout LFSCK finds crashed "
+                              "LAST_ID file (2) for the sequence "LPX64
+                              ", old value "LPU64", known value "LPU64"\n",
+                              lfsck_lfsck2name(lfsck), lls->lls_seq,
+                              lls->lls_lastid, oid);
                }
 
                lls->lls_lastid = oid;
@@ -4753,20 +5103,17 @@ static int lfsck_layout_master_post(const struct lu_env *env,
                lo->ll_status = LS_SCANNING_PHASE2;
                lo->ll_flags |= LF_SCANNED_ONCE;
                lo->ll_flags &= ~LF_UPGRADE;
-               list_del_init(&com->lc_link);
-               list_add_tail(&com->lc_link, &lfsck->li_list_double_scan);
+               list_move_tail(&com->lc_link, &lfsck->li_list_double_scan);
        } else if (result == 0) {
                lo->ll_status = lfsck->li_status;
                if (lo->ll_status == 0)
                        lo->ll_status = LS_STOPPED;
                if (lo->ll_status != LS_PAUSED) {
-                       list_del_init(&com->lc_link);
-                       list_add_tail(&com->lc_link, &lfsck->li_list_idle);
+                       list_move_tail(&com->lc_link, &lfsck->li_list_idle);
                }
        } else {
                lo->ll_status = LS_FAILED;
-               list_del_init(&com->lc_link);
-               list_add_tail(&com->lc_link, &lfsck->li_list_idle);
+               list_move_tail(&com->lc_link, &lfsck->li_list_idle);
        }
        spin_unlock(&lfsck->li_lock);
 
@@ -4781,6 +5128,9 @@ static int lfsck_layout_master_post(const struct lu_env *env,
        rc = lfsck_layout_store(env, com);
        up_write(&com->lc_sem);
 
+       CDEBUG(D_LFSCK, "%s: layout LFSCK master post done: rc = %d\n",
+              lfsck_lfsck2name(lfsck), rc);
+
        RETURN(rc);
 }
 
@@ -4800,7 +5150,6 @@ static int lfsck_layout_slave_post(const struct lu_env *env,
        LASSERT(lfsck->li_out_notify != NULL);
 
        down_write(&com->lc_sem);
-
        spin_lock(&lfsck->li_lock);
        if (!init)
                lo->ll_pos_last_checkpoint =
@@ -4811,22 +5160,22 @@ static int lfsck_layout_slave_post(const struct lu_env *env,
                if (lo->ll_flags & LF_CRASHED_LASTID) {
                        done = true;
                        lo->ll_flags &= ~LF_CRASHED_LASTID;
+
+                       CDEBUG(D_LFSCK, "%s: layout LFSCK has rebuilt "
+                              "crashed LAST_ID files successfully\n",
+                              lfsck_lfsck2name(lfsck));
                }
                lo->ll_flags &= ~LF_UPGRADE;
-               list_del_init(&com->lc_link);
-               list_add_tail(&com->lc_link, &lfsck->li_list_double_scan);
+               list_move_tail(&com->lc_link, &lfsck->li_list_double_scan);
        } else if (result == 0) {
                lo->ll_status = lfsck->li_status;
                if (lo->ll_status == 0)
                        lo->ll_status = LS_STOPPED;
-               if (lo->ll_status != LS_PAUSED) {
-                       list_del_init(&com->lc_link);
-                       list_add_tail(&com->lc_link, &lfsck->li_list_idle);
-               }
+               if (lo->ll_status != LS_PAUSED)
+                       list_move_tail(&com->lc_link, &lfsck->li_list_idle);
        } else {
                lo->ll_status = LS_FAILED;
-               list_del_init(&com->lc_link);
-               list_add_tail(&com->lc_link, &lfsck->li_list_idle);
+               list_move_tail(&com->lc_link, &lfsck->li_list_idle);
        }
        spin_unlock(&lfsck->li_lock);
 
@@ -4843,7 +5192,6 @@ static int lfsck_layout_slave_post(const struct lu_env *env,
        }
 
        rc = lfsck_layout_store(env, com);
-
        up_write(&com->lc_sem);
 
        lfsck_layout_slave_notify_master(env, com, LE_PHASE1_DONE, result);
@@ -4851,73 +5199,60 @@ static int lfsck_layout_slave_post(const struct lu_env *env,
        if (result <= 0)
                lfsck_rbtree_cleanup(env, com);
 
+       CDEBUG(D_LFSCK, "%s: layout LFSCK slave post done: rc = %d\n",
+              lfsck_lfsck2name(lfsck), rc);
+
        return rc;
 }
 
 static int lfsck_layout_dump(const struct lu_env *env,
-                            struct lfsck_component *com, char *buf, int len)
+                            struct lfsck_component *com, struct seq_file *m)
 {
        struct lfsck_instance   *lfsck = com->lc_lfsck;
        struct lfsck_bookmark   *bk    = &lfsck->li_bookmark_ram;
        struct lfsck_layout     *lo    = com->lc_file_ram;
-       int                      save  = len;
-       int                      ret   = -ENOSPC;
        int                      rc;
 
        down_read(&com->lc_sem);
-       rc = snprintf(buf, len,
-                     "name: lfsck_layout\n"
+       seq_printf(m, "name: lfsck_layout\n"
                      "magic: %#x\n"
                      "version: %d\n"
                      "status: %s\n",
                      lo->ll_magic,
                      bk->lb_version,
                      lfsck_status2names(lo->ll_status));
-       if (rc <= 0)
-               goto out;
 
-       buf += rc;
-       len -= rc;
-       rc = lfsck_bits_dump(&buf, &len, lo->ll_flags, lfsck_flags_names,
-                            "flags");
+       rc = lfsck_bits_dump(m, lo->ll_flags, lfsck_flags_names, "flags");
        if (rc < 0)
                goto out;
 
-       rc = lfsck_bits_dump(&buf, &len, bk->lb_param, lfsck_param_names,
-                            "param");
+       rc = lfsck_bits_dump(m, bk->lb_param, lfsck_param_names, "param");
        if (rc < 0)
                goto out;
 
-       rc = lfsck_time_dump(&buf, &len, lo->ll_time_last_complete,
+       rc = lfsck_time_dump(m, lo->ll_time_last_complete,
                             "time_since_last_completed");
        if (rc < 0)
                goto out;
 
-       rc = lfsck_time_dump(&buf, &len, lo->ll_time_latest_start,
+       rc = lfsck_time_dump(m, lo->ll_time_latest_start,
                             "time_since_latest_start");
        if (rc < 0)
                goto out;
 
-       rc = lfsck_time_dump(&buf, &len, lo->ll_time_last_checkpoint,
+       rc = lfsck_time_dump(m, lo->ll_time_last_checkpoint,
                             "time_since_last_checkpoint");
        if (rc < 0)
                goto out;
 
-       rc = snprintf(buf, len,
-                     "latest_start_position: "LPU64"\n"
+       seq_printf(m, "latest_start_position: "LPU64"\n"
                      "last_checkpoint_position: "LPU64"\n"
                      "first_failure_position: "LPU64"\n",
                      lo->ll_pos_latest_start,
                      lo->ll_pos_last_checkpoint,
                      lo->ll_pos_first_inconsistent);
-       if (rc <= 0)
-               goto out;
-
-       buf += rc;
-       len -= rc;
 
-       rc = snprintf(buf, len,
-                     "success_count: %u\n"
+       seq_printf(m, "success_count: %u\n"
                      "repaired_dangling: "LPU64"\n"
                      "repaired_unmatched_pair: "LPU64"\n"
                      "repaired_multiple_referenced: "LPU64"\n"
@@ -4937,11 +5272,6 @@ static int lfsck_layout_dump(const struct lu_env *env,
                      lo->ll_objs_skipped,
                      lo->ll_objs_failed_phase1,
                      lo->ll_objs_failed_phase2);
-       if (rc <= 0)
-               goto out;
-
-       buf += rc;
-       len -= rc;
 
        if (lo->ll_status == LS_SCANNING_PHASE1) {
                __u64 pos;
@@ -4959,8 +5289,7 @@ static int lfsck_layout_dump(const struct lu_env *env,
                        do_div(new_checked, duration);
                if (rtime != 0)
                        do_div(speed, rtime);
-               rc = snprintf(buf, len,
-                             "checked_phase1: "LPU64"\n"
+               seq_printf(m, "checked_phase1: "LPU64"\n"
                              "checked_phase2: "LPU64"\n"
                              "run_time_phase1: %u seconds\n"
                              "run_time_phase2: %u seconds\n"
@@ -4974,11 +5303,6 @@ static int lfsck_layout_dump(const struct lu_env *env,
                              lo->ll_run_time_phase2,
                              speed,
                              new_checked);
-               if (rc <= 0)
-                       goto out;
-
-               buf += rc;
-               len -= rc;
 
                LASSERT(lfsck->li_di_oit != NULL);
 
@@ -4991,12 +5315,8 @@ static int lfsck_layout_dump(const struct lu_env *env,
                pos = iops->store(env, lfsck->li_di_oit);
                if (!lfsck->li_current_oit_processed)
                        pos--;
-               rc = snprintf(buf, len, "current_position: "LPU64"\n", pos);
-               if (rc <= 0)
-                       goto out;
+               seq_printf(m, "current_position: "LPU64"\n", pos);
 
-               buf += rc;
-               len -= rc;
        } else if (lo->ll_status == LS_SCANNING_PHASE2) {
                cfs_duration_t duration = cfs_time_current() -
                                          lfsck->li_time_last_checkpoint;
@@ -5014,29 +5334,26 @@ static int lfsck_layout_dump(const struct lu_env *env,
                        do_div(speed1, lo->ll_run_time_phase1);
                if (rtime != 0)
                        do_div(speed2, rtime);
-               rc = snprintf(buf, len,
-                             "checked_phase1: "LPU64"\n"
-                             "checked_phase2: "LPU64"\n"
-                             "run_time_phase1: %u seconds\n"
-                             "run_time_phase2: %u seconds\n"
-                             "average_speed_phase1: "LPU64" items/sec\n"
-                             "average_speed_phase2: "LPU64" items/sec\n"
-                             "real-time_speed_phase1: N/A\n"
-                             "real-time_speed_phase2: "LPU64" items/sec\n"
-                             "current_position: "DFID"\n",
-                             lo->ll_objs_checked_phase1,
-                             checked,
-                             lo->ll_run_time_phase1,
-                             rtime,
-                             speed1,
-                             speed2,
-                             new_checked,
-                             PFID(&com->lc_fid_latest_scanned_phase2));
+               rc = seq_printf(m, "checked_phase1: "LPU64"\n"
+                               "checked_phase2: "LPU64"\n"
+                               "run_time_phase1: %u seconds\n"
+                               "run_time_phase2: %u seconds\n"
+                               "average_speed_phase1: "LPU64" items/sec\n"
+                               "average_speed_phase2: "LPU64" items/sec\n"
+                               "real-time_speed_phase1: N/A\n"
+                               "real-time_speed_phase2: "LPU64" items/sec\n"
+                               "current_position: "DFID"\n",
+                               lo->ll_objs_checked_phase1,
+                               checked,
+                               lo->ll_run_time_phase1,
+                               rtime,
+                               speed1,
+                               speed2,
+                               new_checked,
+                               PFID(&com->lc_fid_latest_scanned_phase2));
                if (rc <= 0)
                        goto out;
 
-               buf += rc;
-               len -= rc;
        } else {
                __u64 speed1 = lo->ll_objs_checked_phase1;
                __u64 speed2 = lo->ll_objs_checked_phase2;
@@ -5045,34 +5362,26 @@ static int lfsck_layout_dump(const struct lu_env *env,
                        do_div(speed1, lo->ll_run_time_phase1);
                if (lo->ll_run_time_phase2 != 0)
                        do_div(speed2, lo->ll_run_time_phase2);
-               rc = snprintf(buf, len,
-                             "checked_phase1: "LPU64"\n"
-                             "checked_phase2: "LPU64"\n"
-                             "run_time_phase1: %u seconds\n"
-                             "run_time_phase2: %u seconds\n"
-                             "average_speed_phase1: "LPU64" items/sec\n"
-                             "average_speed_phase2: "LPU64" objs/sec\n"
-                             "real-time_speed_phase1: N/A\n"
-                             "real-time_speed_phase2: N/A\n"
-                             "current_position: N/A\n",
-                             lo->ll_objs_checked_phase1,
-                             lo->ll_objs_checked_phase2,
-                             lo->ll_run_time_phase1,
-                             lo->ll_run_time_phase2,
-                             speed1,
-                             speed2);
-               if (rc <= 0)
-                       goto out;
-
-               buf += rc;
-               len -= rc;
+               seq_printf(m, "checked_phase1: "LPU64"\n"
+                          "checked_phase2: "LPU64"\n"
+                          "run_time_phase1: %u seconds\n"
+                          "run_time_phase2: %u seconds\n"
+                          "average_speed_phase1: "LPU64" items/sec\n"
+                          "average_speed_phase2: "LPU64" objs/sec\n"
+                          "real-time_speed_phase1: N/A\n"
+                          "real-time_speed_phase2: N/A\n"
+                          "current_position: N/A\n",
+                          lo->ll_objs_checked_phase1,
+                          lo->ll_objs_checked_phase2,
+                          lo->ll_run_time_phase1,
+                          lo->ll_run_time_phase2,
+                          speed1,
+                          speed2);
        }
-       ret = save - len;
-
 out:
        up_read(&com->lc_sem);
 
-       return ret;
+       return rc;
 }
 
 static int lfsck_layout_master_double_scan(const struct lu_env *env,
@@ -5115,6 +5424,9 @@ static int lfsck_layout_slave_double_scan(const struct lu_env *env,
                RETURN(0);
        }
 
+       CDEBUG(D_LFSCK, "%s: layout LFSCK slave phase2 scan start\n",
+              lfsck_lfsck2name(lfsck));
+
        atomic_inc(&lfsck->li_double_scan_count);
 
        com->lc_new_checked = 0;
@@ -5161,6 +5473,10 @@ done:
        if (atomic_dec_and_test(&lfsck->li_double_scan_count))
                wake_up_all(&lfsck->li_thread.t_ctl_waitq);
 
+       CDEBUG(D_LFSCK, "%s: layout LFSCK slave phase2 scan finished, "
+              "status %d: rc = %d\n",
+              lfsck_lfsck2name(lfsck), lo->ll_status, rc);
+
        return rc;
 }
 
@@ -5194,6 +5510,10 @@ static void lfsck_layout_master_data_release(const struct lu_env *env,
                                 ltd_layout_list) {
                list_del_init(&ltd->ltd_layout_list);
        }
+       spin_unlock(&ltds->ltd_lock);
+
+       ltds = &lfsck->li_mdt_descs;
+       spin_lock(&ltds->ltd_lock);
        list_for_each_entry_safe(ltd, next, &llmd->llmd_mdt_phase1_list,
                                 ltd_layout_phase_list) {
                list_del_init(&ltd->ltd_layout_phase_list);
@@ -5283,6 +5603,11 @@ static int lfsck_layout_master_in_notify(const struct lu_env *env,
                RETURN(rc);
        }
 
+       CDEBUG(D_LFSCK, "%s: layout LFSCK master handle notify %u "
+              "from %s %x, status %d\n", lfsck_lfsck2name(lfsck),
+              lr->lr_event, (lr->lr_flags & LEF_TO_OST) ? "OST" : "MDT",
+              lr->lr_index, lr->lr_status);
+
        if (lr->lr_event != LE_PHASE1_DONE &&
            lr->lr_event != LE_PHASE2_DONE &&
            lr->lr_event != LE_PEER_EXIT)
@@ -5306,10 +5631,6 @@ static int lfsck_layout_master_in_notify(const struct lu_env *env,
                if (lr->lr_status <= 0) {
                        ltd->ltd_layout_done = 1;
                        list_del_init(&ltd->ltd_layout_list);
-                       CWARN("%s: %s %x failed/stopped at phase1: rc = %d.\n",
-                             lfsck_lfsck2name(lfsck),
-                             (lr->lr_flags & LEF_TO_OST) ? "OST" : "MDT",
-                             ltd->ltd_index, lr->lr_status);
                        lo->ll_flags |= LF_INCOMPLETE;
                        fail = true;
                        break;
@@ -5337,13 +5658,8 @@ static int lfsck_layout_master_in_notify(const struct lu_env *env,
                fail = true;
                ltd->ltd_layout_done = 1;
                list_del_init(&ltd->ltd_layout_list);
-               if (!(lfsck->li_bookmark_ram.lb_param & LPF_FAILOUT)) {
-                       CWARN("%s: the peer %s %x exit layout LFSCK.\n",
-                             lfsck_lfsck2name(lfsck),
-                             (lr->lr_flags & LEF_TO_OST) ? "OST" : "MDT",
-                             ltd->ltd_index);
+               if (!(lfsck->li_bookmark_ram.lb_param & LPF_FAILOUT))
                        lo->ll_flags |= LF_INCOMPLETE;
-               }
                break;
        default:
                break;
@@ -5416,6 +5732,9 @@ static int lfsck_layout_slave_in_notify(const struct lu_env *env,
        }
        case LE_PHASE2_DONE:
        case LE_PEER_EXIT:
+               CDEBUG(D_LFSCK, "%s: layout LFSCK slave handle notify %u "
+                      "from MDT %x, status %d\n", lfsck_lfsck2name(lfsck),
+                      lr->lr_event, lr->lr_index, lr->lr_status);
                break;
        default:
                RETURN(-EINVAL);
@@ -5477,7 +5796,7 @@ static int lfsck_layout_master_stop_notify(const struct lu_env *env,
        memset(lr, 0, sizeof(*lr));
        lr->lr_index = lfsck_dev_idx(lfsck->li_bottom);
        lr->lr_event = LE_PEER_EXIT;
-       lr->lr_active = LT_LAYOUT;
+       lr->lr_active = LFSCK_TYPE_LAYOUT;
        lr->lr_status = LS_CO_PAUSED;
        if (ltds == &lfsck->li_ost_descs)
                lr->lr_flags = LEF_TO_OST;
@@ -5493,7 +5812,8 @@ static int lfsck_layout_master_stop_notify(const struct lu_env *env,
                                 lfsck_layout_master_async_interpret,
                                 laia, LFSCK_NOTIFY);
        if (rc != 0) {
-               CERROR("%s: Fail to notify %s %x for co-stop: rc = %d\n",
+               CDEBUG(D_LFSCK, "%s: layout LFSCK fail to notify %s %x "
+                      "for co-stop: rc = %d\n",
                       lfsck_lfsck2name(lfsck),
                       (lr->lr_flags & LEF_TO_OST) ? "OST" : "MDT",
                       ltd->ltd_index, rc);
@@ -5515,10 +5835,17 @@ static int lfsck_layout_slave_join(const struct lu_env *env,
        int                               rc    = 0;
        ENTRY;
 
-       if (!lsp->lsp_index_valid || start == NULL ||
-           !(start->ls_flags & LPF_ALL_TGT) ||
-           !(lfsck->li_bookmark_ram.lb_param & LPF_ALL_TGT))
-               RETURN(-EALREADY);
+       if (start == NULL || !(start->ls_flags & LPF_ORPHAN))
+               RETURN(0);
+
+       if (!lsp->lsp_index_valid)
+               RETURN(-EINVAL);
+
+       /* If someone is running the LFSCK without orphan handling,
+        * it will not maintain the object accessing rbtree. So we
+        * cannot join it for orphan handling. */
+       if (!llsd->llsd_rbtree_valid)
+               RETURN(-EBUSY);
 
        spin_unlock(&lfsck->li_lock);
        rc = lfsck_layout_llst_add(llsd, lsp->lsp_index);
@@ -5589,7 +5916,7 @@ int lfsck_layout_setup(const struct lu_env *env, struct lfsck_instance *lfsck)
        init_rwsem(&com->lc_sem);
        atomic_set(&com->lc_ref, 1);
        com->lc_lfsck = lfsck;
-       com->lc_type = LT_LAYOUT;
+       com->lc_type = LFSCK_TYPE_LAYOUT;
        if (lfsck->li_master) {
                struct lfsck_layout_master_data *llmd;
 
@@ -5667,7 +5994,7 @@ int lfsck_layout_setup(const struct lu_env *env, struct lfsck_instance *lfsck)
                spin_unlock(&lfsck->li_lock);
                break;
        default:
-               CERROR("%s: unknown lfsck_layout status: rc = %u\n",
+               CERROR("%s: unknown lfsck_layout status %d\n",
                       lfsck_lfsck2name(lfsck), lo->ll_status);
                /* fall through */
        case LS_SCANNING_PHASE1:
@@ -5702,8 +6029,11 @@ out:
        if (root != NULL && !IS_ERR(root))
                lu_object_put(env, &root->do_lu);
 
-       if (rc != 0)
+       if (rc != 0) {
                lfsck_component_cleanup(env, com);
+               CERROR("%s: fail to init layout LFSCK component: rc = %d\n",
+                      lfsck_lfsck2name(lfsck), rc);
+       }
 
        return rc;
 }
@@ -5791,6 +6121,9 @@ static void lfsck_layout_destroy_orphan(const struct lu_env *env,
 stop:
        dt_trans_stop(env, dev, handle);
 
+       CDEBUG(D_LFSCK, "destroy orphan OST-object "DFID": rc = %d\n",
+              PFID(lfsck_dto2fid(obj)), rc);
+
        RETURN_EXIT;
 }
 
@@ -5857,7 +6190,7 @@ static struct dt_it *lfsck_orphan_it_init(const struct lu_env *env,
        if (unlikely(lfsck == NULL))
                RETURN(ERR_PTR(-ENXIO));
 
-       com = lfsck_component_find(lfsck, LT_LAYOUT);
+       com = lfsck_component_find(lfsck, LFSCK_TYPE_LAYOUT);
        if (unlikely(com == NULL))
                GOTO(out, rc = -ENOENT);
 
@@ -5911,6 +6244,10 @@ static struct dt_it *lfsck_orphan_it_init(const struct lu_env *env,
 out:
        if (com != NULL)
                lfsck_component_put(env, com);
+
+       CDEBUG(D_LFSCK, "%s: init the orphan iteration: rc = %d\n",
+              lfsck_lfsck2name(lfsck), rc);
+
        lfsck_instance_put(env, lfsck);
        if (rc != 0) {
                if (it != NULL)
@@ -5931,6 +6268,9 @@ static void lfsck_orphan_it_fini(const struct lu_env *env,
        struct lfsck_layout_slave_target *llst;
 
        if (com != NULL) {
+               CDEBUG(D_LFSCK, "%s: fini the orphan iteration\n",
+                      lfsck_lfsck2name(com->lc_lfsck));
+
                llsd = com->lc_data;
                read_unlock(&llsd->llsd_rb_lock);
                llst = it->loi_llst;
@@ -6060,7 +6400,8 @@ again1:
        }
 
        dt_read_lock(env, obj, 0);
-       if (!dt_object_exists(obj)) {
+       if (dt_object_exists(obj) == 0 ||
+           lfsck_is_dead_obj(obj)) {
                dt_read_unlock(env, obj);
                lfsck_object_put(env, obj);
                pos++;
@@ -6231,10 +6572,11 @@ static int lfsck_orphan_it_load(const struct lu_env *env,
        LASSERT(llst != NULL);
 
        if (hash != llst->llst_hash) {
-               CWARN("%s: the given hash "LPU64" for orphan iteration does "
-                     "not match the one when fini "LPU64", to be reset.\n",
-                     lfsck_lfsck2name(it->loi_com->lc_lfsck), hash,
-                     llst->llst_hash);
+               CDEBUG(D_LFSCK, "%s: the given hash "LPU64" for orphan "
+                      "iteration does not match the one when fini "
+                      LPU64", to be reset.\n",
+                      lfsck_lfsck2name(it->loi_com->lc_lfsck), hash,
+                      llst->llst_hash);
                fid_zero(&llst->llst_fid);
                llst->llst_hash = 0;
        }