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LU-3336 lfsck: use rbtree to record OST-object accessing
[fs/lustre-release.git] / lustre / lfsck / lfsck_layout.c
index 402cca7..9dd4d7f 100644 (file)
@@ -34,6 +34,7 @@
 #define DEBUG_SUBSYSTEM S_LFSCK
 
 #include <linux/bitops.h>
+#include <linux/rbtree.h>
 
 #include <lustre/lustre_idl.h>
 #include <lu_object.h>
@@ -43,6 +44,8 @@
 #include <lustre_lib.h>
 #include <lustre_net.h>
 #include <lustre/lustre_user.h>
+#include <md_object.h>
+#include <obd_class.h>
 
 #include "lfsck_internal.h"
 
 
 static const char lfsck_layout_name[] = "lfsck_layout";
 
+struct lfsck_layout_seq {
+       struct list_head         lls_list;
+       __u64                    lls_seq;
+       __u64                    lls_lastid;
+       __u64                    lls_lastid_known;
+       struct dt_object        *lls_lastid_obj;
+       unsigned int             lls_dirty:1;
+};
+
+struct lfsck_layout_slave_target {
+       /* link into lfsck_layout_slave_data::llsd_master_list. */
+       struct list_head        llst_list;
+       __u64                   llst_gen;
+       atomic_t                llst_ref;
+       __u32                   llst_index;
+};
+
+struct lfsck_layout_slave_data {
+       /* list for lfsck_layout_seq */
+       struct list_head         llsd_seq_list;
+
+       /* list for the masters involve layout verification. */
+       struct list_head         llsd_master_list;
+       spinlock_t               llsd_lock;
+       __u64                    llsd_touch_gen;
+       struct dt_object        *llsd_rb_obj;
+       struct rb_root           llsd_rb_root;
+       rwlock_t                 llsd_rb_lock;
+       unsigned int             llsd_rbtree_valid:1;
+};
+
+struct lfsck_layout_object {
+       struct dt_object        *llo_obj;
+       struct lu_attr           llo_attr;
+       atomic_t                 llo_ref;
+       __u16                    llo_gen;
+};
+
+struct lfsck_layout_req {
+       struct list_head                 llr_list;
+       struct lfsck_layout_object      *llr_parent;
+       struct dt_object                *llr_child;
+       __u32                            llr_ost_idx;
+       __u32                            llr_lov_idx; /* offset in LOV EA */
+};
+
+struct lfsck_layout_master_data {
+       spinlock_t              llmd_lock;
+       struct list_head        llmd_req_list;
+
+       /* list for the ost targets involve layout verification. */
+       struct list_head        llmd_ost_list;
+
+       /* list for the ost targets in phase1 scanning. */
+       struct list_head        llmd_ost_phase1_list;
+
+       /* list for the ost targets in phase1 scanning. */
+       struct list_head        llmd_ost_phase2_list;
+
+       /* list for the mdt targets involve layout verification. */
+       struct list_head        llmd_mdt_list;
+
+       /* list for the mdt targets in phase1 scanning. */
+       struct list_head        llmd_mdt_phase1_list;
+
+       /* list for the mdt targets in phase1 scanning. */
+       struct list_head        llmd_mdt_phase2_list;
+
+       struct ptlrpc_thread    llmd_thread;
+       __u32                   llmd_touch_gen;
+       int                     llmd_prefetched;
+       int                     llmd_assistant_status;
+       int                     llmd_post_result;
+       unsigned int            llmd_to_post:1,
+                               llmd_to_double_scan:1,
+                               llmd_in_double_scan:1,
+                               llmd_exit:1;
+};
+
+struct lfsck_layout_slave_async_args {
+       struct obd_export                *llsaa_exp;
+       struct lfsck_component           *llsaa_com;
+       struct lfsck_layout_slave_target *llsaa_llst;
+};
+
+static struct lfsck_layout_object *
+lfsck_layout_object_init(const struct lu_env *env, struct dt_object *obj,
+                        __u16 gen)
+{
+       struct lfsck_layout_object *llo;
+       int                         rc;
+
+       OBD_ALLOC_PTR(llo);
+       if (llo == NULL)
+               return ERR_PTR(-ENOMEM);
+
+       rc = dt_attr_get(env, obj, &llo->llo_attr, BYPASS_CAPA);
+       if (rc != 0) {
+               OBD_FREE_PTR(llo);
+
+               return ERR_PTR(rc);
+       }
+
+       lu_object_get(&obj->do_lu);
+       llo->llo_obj = obj;
+       /* The gen can be used to check whether some others have changed the
+        * file layout after LFSCK pre-fetching but before real verification. */
+       llo->llo_gen = gen;
+       atomic_set(&llo->llo_ref, 1);
+
+       return llo;
+}
+
+static inline void
+lfsck_layout_llst_put(struct lfsck_layout_slave_target *llst)
+{
+       if (atomic_dec_and_test(&llst->llst_ref)) {
+               LASSERT(list_empty(&llst->llst_list));
+
+               OBD_FREE_PTR(llst);
+       }
+}
+
+static inline int
+lfsck_layout_llst_add(struct lfsck_layout_slave_data *llsd, __u32 index)
+{
+       struct lfsck_layout_slave_target *llst;
+       struct lfsck_layout_slave_target *tmp;
+       int                               rc   = 0;
+
+       OBD_ALLOC_PTR(llst);
+       if (llst == NULL)
+               return -ENOMEM;
+
+       INIT_LIST_HEAD(&llst->llst_list);
+       llst->llst_gen = 0;
+       llst->llst_index = index;
+       atomic_set(&llst->llst_ref, 1);
+
+       spin_lock(&llsd->llsd_lock);
+       list_for_each_entry(tmp, &llsd->llsd_master_list, llst_list) {
+               if (tmp->llst_index == index) {
+                       rc = -EALREADY;
+                       break;
+               }
+       }
+       if (rc == 0)
+               list_add_tail(&llst->llst_list, &llsd->llsd_master_list);
+       spin_unlock(&llsd->llsd_lock);
+
+       if (rc != 0)
+               OBD_FREE_PTR(llst);
+
+       return rc;
+}
+
+static inline void
+lfsck_layout_llst_del(struct lfsck_layout_slave_data *llsd,
+                     struct lfsck_layout_slave_target *llst)
+{
+       bool del = false;
+
+       spin_lock(&llsd->llsd_lock);
+       if (!list_empty(&llst->llst_list)) {
+               list_del_init(&llst->llst_list);
+               del = true;
+       }
+       spin_unlock(&llsd->llsd_lock);
+
+       if (del)
+               lfsck_layout_llst_put(llst);
+}
+
+static inline struct lfsck_layout_slave_target *
+lfsck_layout_llst_find_and_del(struct lfsck_layout_slave_data *llsd,
+                              __u32 index)
+{
+       struct lfsck_layout_slave_target *llst;
+
+       spin_lock(&llsd->llsd_lock);
+       list_for_each_entry(llst, &llsd->llsd_master_list, llst_list) {
+               if (llst->llst_index == index) {
+                       list_del_init(&llst->llst_list);
+                       spin_unlock(&llsd->llsd_lock);
+
+                       return llst;
+               }
+       }
+       spin_unlock(&llsd->llsd_lock);
+
+       return NULL;
+}
+
+static inline void lfsck_layout_object_put(const struct lu_env *env,
+                                          struct lfsck_layout_object *llo)
+{
+       if (atomic_dec_and_test(&llo->llo_ref)) {
+               lfsck_object_put(env, llo->llo_obj);
+               OBD_FREE_PTR(llo);
+       }
+}
+
+static struct lfsck_layout_req *
+lfsck_layout_req_init(struct lfsck_layout_object *parent,
+                     struct dt_object *child, __u32 ost_idx, __u32 lov_idx)
+{
+       struct lfsck_layout_req *llr;
+
+       OBD_ALLOC_PTR(llr);
+       if (llr == NULL)
+               return ERR_PTR(-ENOMEM);
+
+       INIT_LIST_HEAD(&llr->llr_list);
+       atomic_inc(&parent->llo_ref);
+       llr->llr_parent = parent;
+       llr->llr_child = child;
+       llr->llr_ost_idx = ost_idx;
+       llr->llr_lov_idx = lov_idx;
+
+       return llr;
+}
+
+static inline void lfsck_layout_req_fini(const struct lu_env *env,
+                                        struct lfsck_layout_req *llr)
+{
+       lu_object_put(env, &llr->llr_child->do_lu);
+       lfsck_layout_object_put(env, llr->llr_parent);
+       OBD_FREE_PTR(llr);
+}
+
+static inline bool lfsck_layout_req_empty(struct lfsck_layout_master_data *llmd)
+{
+       bool empty = false;
+
+       spin_lock(&llmd->llmd_lock);
+       if (list_empty(&llmd->llmd_req_list))
+               empty = true;
+       spin_unlock(&llmd->llmd_lock);
+
+       return empty;
+}
+
+static int lfsck_layout_get_lovea(const struct lu_env *env,
+                                 struct dt_object *obj,
+                                 struct lu_buf *buf, ssize_t *buflen)
+{
+       int rc;
+
+again:
+       rc = dt_xattr_get(env, obj, buf, XATTR_NAME_LOV, BYPASS_CAPA);
+       if (rc == -ERANGE) {
+               rc = dt_xattr_get(env, obj, &LU_BUF_NULL, XATTR_NAME_LOV,
+                                 BYPASS_CAPA);
+               if (rc <= 0)
+                       return rc;
+
+               lu_buf_realloc(buf, rc);
+               if (buflen != NULL)
+                       *buflen = buf->lb_len;
+
+               if (buf->lb_buf == NULL)
+                       return -ENOMEM;
+
+               goto again;
+       }
+
+       if (rc == -ENODATA)
+               rc = 0;
+
+       if (rc <= 0)
+               return rc;
+
+       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;
+
+               goto again;
+       }
+
+       return rc;
+}
+
+static int lfsck_layout_verify_header(struct lov_mds_md_v1 *lmm)
+{
+       __u32 magic;
+       __u32 patten;
+
+       magic = le32_to_cpu(lmm->lmm_magic);
+       /* If magic crashed, keep it there. Sometime later, during OST-object
+        * orphan handling, if some OST-object(s) back-point to it, it can be
+        * verified and repaired. */
+       if (magic != LOV_MAGIC_V1 && magic != LOV_MAGIC_V3)
+               return -EINVAL;
+
+       patten = le32_to_cpu(lmm->lmm_pattern);
+       /* XXX: currently, we only support LOV_PATTERN_RAID0. */
+       if (patten != LOV_PATTERN_RAID0)
+               return -EOPNOTSUPP;
+
+       return 0;
+}
+
+#define LFSCK_RBTREE_BITMAP_SIZE       PAGE_CACHE_SIZE
+#define LFSCK_RBTREE_BITMAP_WIDTH      (LFSCK_RBTREE_BITMAP_SIZE << 3)
+#define LFSCK_RBTREE_BITMAP_MASK       (LFSCK_RBTREE_BITMAP_SIZE - 1)
+
+struct lfsck_rbtree_node {
+       struct rb_node   lrn_node;
+       __u64            lrn_seq;
+       __u32            lrn_first_oid;
+       atomic_t         lrn_known_count;
+       atomic_t         lrn_accessed_count;
+       void            *lrn_known_bitmap;
+       void            *lrn_accessed_bitmap;
+};
+
+static inline int lfsck_rbtree_cmp(struct lfsck_rbtree_node *lrn,
+                                  __u64 seq, __u32 oid)
+{
+       if (seq < lrn->lrn_seq)
+               return -1;
+
+       if (seq > lrn->lrn_seq)
+               return 1;
+
+       if (oid < lrn->lrn_first_oid)
+               return -1;
+
+       if (oid >= lrn->lrn_first_oid + LFSCK_RBTREE_BITMAP_WIDTH)
+               return 1;
+
+       return 0;
+}
+
+/* The caller should hold lock. */
+static struct lfsck_rbtree_node *
+lfsck_rbtree_search(struct lfsck_layout_slave_data *llsd,
+                   const struct lu_fid *fid)
+{
+       struct rb_node           *node = llsd->llsd_rb_root.rb_node;
+       struct lfsck_rbtree_node *lrn;
+       int                       rc;
+
+       while (node != NULL) {
+               lrn = rb_entry(node, struct lfsck_rbtree_node, lrn_node);
+               rc = lfsck_rbtree_cmp(lrn, fid_seq(fid), fid_oid(fid));
+               if (rc < 0)
+                       node = node->rb_left;
+               else if (rc > 0)
+                       node = node->rb_right;
+               else
+                       return lrn;
+       }
+
+       return NULL;
+}
+
+static struct lfsck_rbtree_node *lfsck_rbtree_new(const struct lu_env *env,
+                                                 const struct lu_fid *fid)
+{
+       struct lfsck_rbtree_node *lrn;
+
+       OBD_ALLOC_PTR(lrn);
+       if (lrn == NULL)
+               return ERR_PTR(-ENOMEM);
+
+       OBD_ALLOC(lrn->lrn_known_bitmap, LFSCK_RBTREE_BITMAP_SIZE);
+       if (lrn->lrn_known_bitmap == NULL) {
+               OBD_FREE_PTR(lrn);
+
+               return ERR_PTR(-ENOMEM);
+       }
+
+       OBD_ALLOC(lrn->lrn_accessed_bitmap, LFSCK_RBTREE_BITMAP_SIZE);
+       if (lrn->lrn_accessed_bitmap == NULL) {
+               OBD_FREE(lrn->lrn_known_bitmap, LFSCK_RBTREE_BITMAP_SIZE);
+               OBD_FREE_PTR(lrn);
+
+               return ERR_PTR(-ENOMEM);
+       }
+
+       rb_init_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);
+       atomic_set(&lrn->lrn_accessed_count, 0);
+
+       return lrn;
+}
+
+static void lfsck_rbtree_free(struct lfsck_rbtree_node *lrn)
+{
+       OBD_FREE(lrn->lrn_accessed_bitmap, LFSCK_RBTREE_BITMAP_SIZE);
+       OBD_FREE(lrn->lrn_known_bitmap, LFSCK_RBTREE_BITMAP_SIZE);
+       OBD_FREE_PTR(lrn);
+}
+
+/* The caller should hold lock. */
+static struct lfsck_rbtree_node *
+lfsck_rbtree_insert(struct lfsck_layout_slave_data *llsd,
+                   struct lfsck_rbtree_node *lrn)
+{
+       struct rb_node           **pos    = &(llsd->llsd_rb_root.rb_node);
+       struct rb_node            *parent = NULL;
+       struct lfsck_rbtree_node  *tmp;
+       int                        rc;
+
+       while (*pos) {
+               parent = *pos;
+               tmp = rb_entry(*pos, struct lfsck_rbtree_node, lrn_node);
+               rc = lfsck_rbtree_cmp(tmp, lrn->lrn_seq, lrn->lrn_first_oid);
+               if (rc < 0)
+                       pos = &((*pos)->rb_left);
+               else if (rc > 0)
+                       pos = &((*pos)->rb_right);
+               else
+                       return tmp;
+       }
+
+       rb_link_node(&lrn->lrn_node, parent, pos);
+       rb_insert_color(&lrn->lrn_node, &llsd->llsd_rb_root);
+
+       return lrn;
+}
+
+static int lfsck_rbtree_setup(const struct lu_env *env,
+                             struct lfsck_component *com)
+{
+       struct lu_fid                   *fid    = &lfsck_env_info(env)->lti_fid;
+       struct lfsck_instance           *lfsck  = com->lc_lfsck;
+       struct dt_device                *dev    = lfsck->li_bottom;
+       struct lfsck_layout_slave_data  *llsd   = com->lc_data;
+       struct dt_object                *obj;
+
+       fid->f_seq = FID_SEQ_LAYOUT_RBTREE;
+       fid->f_oid = lfsck_dev_idx(dev);
+       fid->f_ver = 0;
+       obj = dt_locate(env, dev, fid);
+       if (IS_ERR(obj))
+               RETURN(PTR_ERR(obj));
+
+       /* XXX: Generate an in-RAM object to stand for the layout rbtree.
+        *      Scanning the layout rbtree will be via the iteration over
+        *      the object. In the future, the rbtree may be written onto
+        *      disk with the object.
+        *
+        *      Mark the object to be as exist. */
+       obj->do_lu.lo_header->loh_attr |= LOHA_EXISTS;
+       llsd->llsd_rb_obj = obj;
+       llsd->llsd_rbtree_valid = 1;
+       dev->dd_record_fid_accessed = 1;
+
+       return 0;
+}
+
+static void lfsck_rbtree_cleanup(const struct lu_env *env,
+                                struct lfsck_component *com)
+{
+       struct lfsck_instance           *lfsck = com->lc_lfsck;
+       struct lfsck_layout_slave_data  *llsd  = com->lc_data;
+       struct rb_node                  *node  = rb_first(&llsd->llsd_rb_root);
+       struct rb_node                  *next;
+       struct lfsck_rbtree_node        *lrn;
+
+       lfsck->li_bottom->dd_record_fid_accessed = 0;
+       /* Invalid the rbtree, then no others will use it. */
+       write_lock(&llsd->llsd_rb_lock);
+       llsd->llsd_rbtree_valid = 0;
+       write_unlock(&llsd->llsd_rb_lock);
+
+       while (node != NULL) {
+               next = rb_next(node);
+               lrn = rb_entry(node, struct lfsck_rbtree_node, lrn_node);
+               rb_erase(node, &llsd->llsd_rb_root);
+               lfsck_rbtree_free(lrn);
+               node = next;
+       }
+
+       if (llsd->llsd_rb_obj != NULL) {
+               lu_object_put(env, &llsd->llsd_rb_obj->do_lu);
+               llsd->llsd_rb_obj = NULL;
+       }
+}
+
+static void lfsck_rbtree_update_bitmap(const struct lu_env *env,
+                                      struct lfsck_component *com,
+                                      const struct lu_fid *fid,
+                                      bool accessed)
+{
+       struct lfsck_layout_slave_data  *llsd   = com->lc_data;
+       struct lfsck_rbtree_node        *lrn;
+       bool                             insert = false;
+       int                              idx;
+       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;
+
+       if (!fid_is_idif(fid) && !fid_is_norm(fid))
+               RETURN_EXIT;
+
+       read_lock(&llsd->llsd_rb_lock);
+       if (!llsd->llsd_rbtree_valid)
+               GOTO(unlock, rc = 0);
+
+       lrn = lfsck_rbtree_search(llsd, fid);
+       if (lrn == NULL) {
+               struct lfsck_rbtree_node *tmp;
+
+               LASSERT(!insert);
+
+               read_unlock(&llsd->llsd_rb_lock);
+               tmp = lfsck_rbtree_new(env, fid);
+               if (IS_ERR(tmp))
+                       GOTO(out, rc = PTR_ERR(tmp));
+
+               insert = true;
+               write_lock(&llsd->llsd_rb_lock);
+               if (!llsd->llsd_rbtree_valid) {
+                       lfsck_rbtree_free(tmp);
+                       GOTO(unlock, rc = 0);
+               }
+
+               lrn = lfsck_rbtree_insert(llsd, tmp);
+               if (lrn != tmp)
+                       lfsck_rbtree_free(tmp);
+       }
+
+       idx = fid_oid(fid) & LFSCK_RBTREE_BITMAP_MASK;
+       /* Any accessed object must be a known object. */
+       if (!test_and_set_bit(idx, lrn->lrn_known_bitmap))
+               atomic_inc(&lrn->lrn_known_count);
+       if (accessed) {
+               if (!test_and_set_bit(idx, lrn->lrn_accessed_bitmap))
+                       atomic_inc(&lrn->lrn_accessed_count);
+       }
+
+       GOTO(unlock, rc = 0);
+
+unlock:
+       if (insert)
+               write_unlock(&llsd->llsd_rb_lock);
+       else
+               read_unlock(&llsd->llsd_rb_lock);
+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",
+                      lfsck_lfsck2name(com->lc_lfsck), rc);
+               lo->ll_flags |= LF_INCOMPLETE;
+               lfsck_rbtree_cleanup(env, com);
+       }
+}
+
 static void lfsck_layout_le_to_cpu(struct lfsck_layout *des,
                                   const struct lfsck_layout *src)
 {
@@ -213,71 +781,2611 @@ static int lfsck_layout_init(const struct lu_env *env,
        return rc;
 }
 
-/* layout APIs */
-/* XXX: Some to be implemented in other patch(es). */
-
-static int lfsck_layout_reset(const struct lu_env *env,
-                             struct lfsck_component *com, bool init)
+static int fid_is_for_ostobj(const struct lu_env *env, struct dt_device *dt,
+                            struct dt_object *obj, const struct lu_fid *fid)
 {
-       struct lfsck_layout     *lo    = com->lc_file_ram;
+       struct seq_server_site  *ss     = lu_site2seq(dt->dd_lu_dev.ld_site);
+       struct lu_seq_range      range  = { 0 };
+       struct lustre_mdt_attrs *lma;
        int                      rc;
 
-       down_write(&com->lc_sem);
-       if (init) {
-               memset(lo, 0, com->lc_file_size);
-       } else {
-               __u32 count = lo->ll_success_count;
-               __u64 last_time = lo->ll_time_last_complete;
+       fld_range_set_any(&range);
+       rc = fld_server_lookup(env, ss->ss_server_fld, fid_seq(fid), &range);
+       if (rc == 0) {
+               if (fld_range_is_ost(&range))
+                       return 1;
 
-               memset(lo, 0, com->lc_file_size);
-               lo->ll_success_count = count;
-               lo->ll_time_last_complete = last_time;
+               return 0;
        }
 
-       lo->ll_magic = LFSCK_LAYOUT_MAGIC;
-       lo->ll_status = LS_INIT;
+       lma = &lfsck_env_info(env)->lti_lma;
+       rc = dt_xattr_get(env, obj, lfsck_buf_get(env, lma, sizeof(*lma)),
+                         XATTR_NAME_LMA, BYPASS_CAPA);
+       if (rc == sizeof(*lma)) {
+               lustre_lma_swab(lma);
 
-       rc = lfsck_layout_store(env, com);
-       up_write(&com->lc_sem);
+               return lma->lma_compat & LMAC_FID_ON_OST ? 1 : 0;
+       }
 
-       return rc;
-}
+       rc = dt_xattr_get(env, obj, &LU_BUF_NULL, XATTR_NAME_FID, BYPASS_CAPA);
 
-static void lfsck_layout_fail(const struct lu_env *env,
-                             struct lfsck_component *com, bool new_checked)
-{
+       return rc > 0;
 }
 
-static int lfsck_layout_checkpoint(const struct lu_env *env,
-                                  struct lfsck_component *com, bool init)
+static struct lfsck_layout_seq *
+lfsck_layout_seq_lookup(struct lfsck_layout_slave_data *llsd, __u64 seq)
 {
-       return 0;
+       struct lfsck_layout_seq *lls;
+
+       list_for_each_entry(lls, &llsd->llsd_seq_list, lls_list) {
+               if (lls->lls_seq == seq)
+                       return lls;
+
+               if (lls->lls_seq > seq)
+                       return NULL;
+       }
+
+       return NULL;
 }
 
-static int lfsck_layout_master_prep(const struct lu_env *env,
-                                   struct lfsck_component *com)
+static void
+lfsck_layout_seq_insert(struct lfsck_layout_slave_data *llsd,
+                       struct lfsck_layout_seq *lls)
 {
-       return 0;
+       struct lfsck_layout_seq *tmp;
+       struct list_head        *pos = &llsd->llsd_seq_list;
+
+       list_for_each_entry(tmp, &llsd->llsd_seq_list, lls_list) {
+               if (lls->lls_seq < tmp->lls_seq) {
+                       pos = &tmp->lls_list;
+                       break;
+               }
+       }
+       list_add_tail(&lls->lls_list, pos);
 }
 
-static int lfsck_layout_slave_prep(const struct lu_env *env,
-                                  struct lfsck_component *com)
+static int
+lfsck_layout_lastid_create(const struct lu_env *env,
+                          struct lfsck_instance *lfsck,
+                          struct dt_object *obj)
 {
-       return 0;
+       struct lfsck_thread_info *info   = lfsck_env_info(env);
+       struct lu_attr           *la     = &info->lti_la;
+       struct dt_object_format  *dof    = &info->lti_dof;
+       struct lfsck_bookmark    *bk     = &lfsck->li_bookmark_ram;
+       struct dt_device         *dt     = lfsck->li_bottom;
+       struct thandle           *th;
+       __u64                     lastid = 0;
+       loff_t                    pos    = 0;
+       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;
+
+       memset(la, 0, sizeof(*la));
+       la->la_mode = S_IFREG |  S_IRUGO | S_IWUSR;
+       la->la_valid = LA_MODE | LA_UID | LA_GID;
+       dof->dof_type = dt_mode_to_dft(S_IFREG);
+
+       th = dt_trans_create(env, dt);
+       if (IS_ERR(th))
+               RETURN(rc = PTR_ERR(th));
+
+       rc = dt_declare_create(env, obj, la, NULL, dof, th);
+       if (rc != 0)
+               GOTO(stop, rc);
+
+       rc = dt_declare_record_write(env, obj, sizeof(lastid), pos, th);
+       if (rc != 0)
+               GOTO(stop, rc);
+
+       rc = dt_trans_start_local(env, dt, th);
+       if (rc != 0)
+               GOTO(stop, rc);
+
+       dt_write_lock(env, obj, 0);
+       if (likely(!dt_object_exists(obj))) {
+               rc = dt_create(env, obj, la, NULL, dof, th);
+               if (rc == 0)
+                       rc = dt_record_write(env, obj,
+                               lfsck_buf_get(env, &lastid, sizeof(lastid)),
+                               &pos, th);
+       }
+       dt_write_unlock(env, obj);
+
+       GOTO(stop, rc);
+
+stop:
+       dt_trans_stop(env, dt, th);
+
+       return rc;
 }
 
-static int lfsck_layout_master_exec_oit(const struct lu_env *env,
-                                       struct lfsck_component *com,
-                                       struct dt_object *obj)
+static int
+lfsck_layout_lastid_reload(const struct lu_env *env,
+                          struct lfsck_component *com,
+                          struct lfsck_layout_seq *lls)
 {
+       __u64   lastid;
+       loff_t  pos     = 0;
+       int     rc;
+
+       dt_read_lock(env, lls->lls_lastid_obj, 0);
+       rc = dt_record_read(env, lls->lls_lastid_obj,
+                           lfsck_buf_get(env, &lastid, sizeof(lastid)), &pos);
+       dt_read_unlock(env, lls->lls_lastid_obj);
+       if (unlikely(rc != 0))
+               return rc;
+
+       lastid = le64_to_cpu(lastid);
+       if (lastid < lls->lls_lastid_known) {
+               struct lfsck_instance   *lfsck  = com->lc_lfsck;
+               struct lfsck_layout     *lo     = com->lc_file_ram;
+
+               lls->lls_lastid = lls->lls_lastid_known;
+               lls->lls_dirty = 1;
+               if (!(lo->ll_flags & LF_CRASHED_LASTID)) {
+                       LASSERT(lfsck->li_out_notify != NULL);
+
+                       lfsck->li_out_notify(env, lfsck->li_out_notify_data,
+                                            LE_LASTID_REBUILDING);
+                       lo->ll_flags |= LF_CRASHED_LASTID;
+               }
+       } else if (lastid >= lls->lls_lastid) {
+               lls->lls_lastid = lastid;
+               lls->lls_dirty = 0;
+       }
+
        return 0;
 }
 
-static int lfsck_layout_slave_exec_oit(const struct lu_env *env,
-                                      struct lfsck_component *com,
-                                      struct dt_object *obj)
+static int
+lfsck_layout_lastid_store(const struct lu_env *env,
+                         struct lfsck_component *com)
 {
-       return 0;
+       struct lfsck_instance           *lfsck  = com->lc_lfsck;
+       struct lfsck_bookmark           *bk     = &lfsck->li_bookmark_ram;
+       struct dt_device                *dt     = lfsck->li_bottom;
+       struct lfsck_layout_slave_data  *llsd   = com->lc_data;
+       struct lfsck_layout_seq         *lls;
+       struct thandle                  *th;
+       __u64                            lastid;
+       int                              rc     = 0;
+       int                              rc1    = 0;
+
+       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
+
+               CDEBUG(D_LFSCK, "To sync the LAST_ID for <seq> "LPX64
+                      " as <oid> "LPU64"\n", lls->lls_seq, lls->lls_lastid);
+
+               if (bk->lb_param & LPF_DRYRUN) {
+                       lls->lls_dirty = 0;
+                       continue;
+               }
+
+               th = dt_trans_create(env, dt);
+               if (IS_ERR(th)) {
+                       rc1 = PTR_ERR(th);
+                       CERROR("%s: (1) failed to store "LPX64": rc = %d\n",
+                              lfsck_lfsck2name(com->lc_lfsck),
+                              lls->lls_seq, rc1);
+                       continue;
+               }
+
+               rc = dt_declare_record_write(env, lls->lls_lastid_obj,
+                                            sizeof(lastid), pos, th);
+               if (rc != 0)
+                       goto stop;
+
+               rc = dt_trans_start_local(env, dt, th);
+               if (rc != 0)
+                       goto stop;
+
+               lastid = cpu_to_le64(lls->lls_lastid);
+               dt_write_lock(env, lls->lls_lastid_obj, 0);
+               rc = dt_record_write(env, lls->lls_lastid_obj,
+                                    lfsck_buf_get(env, &lastid,
+                                    sizeof(lastid)), &pos, th);
+               dt_write_unlock(env, lls->lls_lastid_obj);
+               if (rc == 0)
+                       lls->lls_dirty = 0;
+
+stop:
+               dt_trans_stop(env, dt, th);
+               if (rc != 0) {
+                       rc1 = rc;
+                       CERROR("%s: (2) failed to store "LPX64": rc = %d\n",
+                              lfsck_lfsck2name(com->lc_lfsck),
+                              lls->lls_seq, rc1);
+               }
+       }
+
+       return rc1;
+}
+
+static int
+lfsck_layout_lastid_load(const struct lu_env *env,
+                        struct lfsck_component *com,
+                        struct lfsck_layout_seq *lls)
+{
+       struct lfsck_instance   *lfsck  = com->lc_lfsck;
+       struct lfsck_layout     *lo     = com->lc_file_ram;
+       struct lu_fid           *fid    = &lfsck_env_info(env)->lti_fid;
+       struct dt_object        *obj;
+       loff_t                   pos    = 0;
+       int                      rc;
+       ENTRY;
+
+       lu_last_id_fid(fid, lls->lls_seq, lfsck_dev_idx(lfsck->li_bottom));
+       obj = dt_locate(env, lfsck->li_bottom, fid);
+       if (IS_ERR(obj))
+               RETURN(PTR_ERR(obj));
+
+       /* LAST_ID crashed, to be rebuilt */
+       if (!dt_object_exists(obj)) {
+               if (!(lo->ll_flags & LF_CRASHED_LASTID)) {
+                       LASSERT(lfsck->li_out_notify != NULL);
+
+                       lfsck->li_out_notify(env, lfsck->li_out_notify_data,
+                                            LE_LASTID_REBUILDING);
+                       lo->ll_flags |= LF_CRASHED_LASTID;
+
+                       if (OBD_FAIL_CHECK(OBD_FAIL_LFSCK_DELAY4) &&
+                           cfs_fail_val > 0) {
+                               struct l_wait_info lwi = LWI_TIMEOUT(
+                                               cfs_time_seconds(cfs_fail_val),
+                                               NULL, NULL);
+
+                               up_write(&com->lc_sem);
+                               l_wait_event(lfsck->li_thread.t_ctl_waitq,
+                                            !thread_is_running(&lfsck->li_thread),
+                                            &lwi);
+                               down_write(&com->lc_sem);
+                       }
+               }
+
+               rc = lfsck_layout_lastid_create(env, lfsck, obj);
+       } else {
+               dt_read_lock(env, obj, 0);
+               rc = dt_read(env, obj,
+                       lfsck_buf_get(env, &lls->lls_lastid, sizeof(__u64)),
+                       &pos);
+               dt_read_unlock(env, obj);
+               if (rc != 0 && rc != sizeof(__u64))
+                       GOTO(out, rc = (rc > 0 ? -EFAULT : rc));
+
+               if (rc == 0 && !(lo->ll_flags & LF_CRASHED_LASTID)) {
+                       LASSERT(lfsck->li_out_notify != NULL);
+
+                       lfsck->li_out_notify(env, lfsck->li_out_notify_data,
+                                            LE_LASTID_REBUILDING);
+                       lo->ll_flags |= LF_CRASHED_LASTID;
+               }
+
+               lls->lls_lastid = le64_to_cpu(lls->lls_lastid);
+               rc = 0;
+       }
+
+       GOTO(out, rc);
+
+out:
+       if (rc != 0)
+               lfsck_object_put(env, obj);
+       else
+               lls->lls_lastid_obj = obj;
+
+       return rc;
+}
+
+static int lfsck_layout_master_async_interpret(const struct lu_env *env,
+                                              struct ptlrpc_request *req,
+                                              void *args, int rc)
+{
+       struct lfsck_async_interpret_args *laia = args;
+       struct lfsck_component            *com  = laia->laia_com;
+       struct lfsck_layout_master_data   *llmd = com->lc_data;
+       struct lfsck_tgt_descs            *ltds = laia->laia_ltds;
+       struct lfsck_tgt_desc             *ltd  = laia->laia_ltd;
+       struct lfsck_request              *lr   = laia->laia_lr;
+
+       switch (lr->lr_event) {
+       case LE_START:
+               if (rc != 0) {
+                       struct lfsck_layout *lo = com->lc_file_ram;
+
+                       lo->ll_flags |= LF_INCOMPLETE;
+                       lfsck_tgt_put(ltd);
+                       break;
+               }
+
+               spin_lock(&ltds->ltd_lock);
+               if (ltd->ltd_dead || ltd->ltd_layout_done) {
+                       spin_unlock(&ltds->ltd_lock);
+                       lfsck_tgt_put(ltd);
+                       break;
+               }
+
+               if (lr->lr_flags & LEF_TO_OST) {
+                       if (list_empty(&ltd->ltd_layout_list))
+                               list_add_tail(&ltd->ltd_layout_list,
+                                             &llmd->llmd_ost_list);
+                       if (list_empty(&ltd->ltd_layout_phase_list))
+                               list_add_tail(&ltd->ltd_layout_phase_list,
+                                             &llmd->llmd_ost_phase1_list);
+               } else {
+                       if (list_empty(&ltd->ltd_layout_list))
+                               list_add_tail(&ltd->ltd_layout_list,
+                                             &llmd->llmd_mdt_list);
+                       if (list_empty(&ltd->ltd_layout_phase_list))
+                               list_add_tail(&ltd->ltd_layout_phase_list,
+                                             &llmd->llmd_mdt_phase1_list);
+               }
+               spin_unlock(&ltds->ltd_lock);
+               lfsck_tgt_put(ltd);
+               break;
+       case LE_STOP:
+       case LE_PHASE1_DONE:
+       case LE_PHASE2_DONE:
+               if (rc != 0)
+                       CERROR("%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;
+
+               if (rc != 0) {
+                       spin_lock(&ltds->ltd_lock);
+                       list_del_init(&ltd->ltd_layout_phase_list);
+                       list_del_init(&ltd->ltd_layout_list);
+                       spin_unlock(&ltds->ltd_lock);
+                       lfsck_tgt_put(ltd);
+                       break;
+               }
+
+               reply = req_capsule_server_get(&req->rq_pill,
+                                              &RMF_LFSCK_REPLY);
+               if (reply == NULL) {
+                       rc = -EPROTO;
+                       CERROR("%s: invalid return value: rc = %d\n",
+                              lfsck_lfsck2name(com->lc_lfsck), rc);
+                       spin_lock(&ltds->ltd_lock);
+                       list_del_init(&ltd->ltd_layout_phase_list);
+                       list_del_init(&ltd->ltd_layout_list);
+                       spin_unlock(&ltds->ltd_lock);
+                       lfsck_tgt_put(ltd);
+                       break;
+               }
+
+               switch (reply->lr_status) {
+               case LS_SCANNING_PHASE1:
+                       break;
+               case LS_SCANNING_PHASE2:
+                       spin_lock(&ltds->ltd_lock);
+                       list_del_init(&ltd->ltd_layout_phase_list);
+                       if (ltd->ltd_dead || ltd->ltd_layout_done) {
+                               spin_unlock(&ltds->ltd_lock);
+                               break;
+                       }
+
+                       if (lr->lr_flags & LEF_TO_OST)
+                               list_add_tail(&ltd->ltd_layout_phase_list,
+                                             &llmd->llmd_ost_phase2_list);
+                       else
+                               list_add_tail(&ltd->ltd_layout_phase_list,
+                                             &llmd->llmd_mdt_phase2_list);
+                       spin_unlock(&ltds->ltd_lock);
+                       break;
+               default:
+                       spin_lock(&ltds->ltd_lock);
+                       list_del_init(&ltd->ltd_layout_phase_list);
+                       list_del_init(&ltd->ltd_layout_list);
+                       spin_unlock(&ltds->ltd_lock);
+                       break;
+               }
+               lfsck_tgt_put(ltd);
+               break;
+       }
+       default:
+               CERROR("%s: unexpected event: rc = %d\n",
+                      lfsck_lfsck2name(com->lc_lfsck), lr->lr_event);
+               break;
+       }
+
+       lfsck_component_put(env, com);
+
+       return 0;
+}
+
+static int lfsck_layout_master_query_others(const struct lu_env *env,
+                                           struct lfsck_component *com)
+{
+       struct lfsck_thread_info          *info  = lfsck_env_info(env);
+       struct lfsck_request              *lr    = &info->lti_lr;
+       struct lfsck_async_interpret_args *laia  = &info->lti_laia;
+       struct lfsck_instance             *lfsck = com->lc_lfsck;
+       struct lfsck_layout_master_data   *llmd  = com->lc_data;
+       struct ptlrpc_request_set         *set;
+       struct lfsck_tgt_descs            *ltds;
+       struct lfsck_tgt_desc             *ltd;
+       struct list_head                  *head;
+       __u32                              cnt   = 0;
+       int                                rc    = 0;
+       int                                rc1   = 0;
+       ENTRY;
+
+       set = ptlrpc_prep_set();
+       if (set == NULL)
+               RETURN(-ENOMEM);
+
+       llmd->llmd_touch_gen++;
+       memset(lr, 0, sizeof(*lr));
+       lr->lr_index = lfsck_dev_idx(lfsck->li_bottom);
+       lr->lr_event = LE_QUERY;
+       lr->lr_active = LT_LAYOUT;
+       laia->laia_com = com;
+       laia->laia_lr = lr;
+
+       if (!list_empty(&llmd->llmd_mdt_phase1_list)) {
+               ltds = &lfsck->li_mdt_descs;
+               lr->lr_flags = 0;
+               head = &llmd->llmd_mdt_phase1_list;
+       } else {
+
+again:
+               ltds = &lfsck->li_ost_descs;
+               lr->lr_flags = LEF_TO_OST;
+               head = &llmd->llmd_ost_phase1_list;
+       }
+
+       laia->laia_ltds = ltds;
+       spin_lock(&ltds->ltd_lock);
+       while (!list_empty(head)) {
+               ltd = list_entry(head->next,
+                                struct lfsck_tgt_desc,
+                                ltd_layout_phase_list);
+               if (ltd->ltd_layout_gen == llmd->llmd_touch_gen)
+                       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);
+               atomic_inc(&ltd->ltd_ref);
+               laia->laia_ltd = ltd;
+               spin_unlock(&ltds->ltd_lock);
+               rc = lfsck_async_request(env, ltd->ltd_exp, lr, set,
+                                        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),
+                              (lr->lr_flags & LEF_TO_OST) ? "OST" : "MDT",
+                              ltd->ltd_index, rc);
+                       lfsck_tgt_put(ltd);
+                       rc1 = rc;
+               } else {
+                       cnt++;
+               }
+               spin_lock(&ltds->ltd_lock);
+       }
+       spin_unlock(&ltds->ltd_lock);
+
+       if (cnt > 0) {
+               rc = ptlrpc_set_wait(set);
+               if (rc < 0) {
+                       ptlrpc_set_destroy(set);
+                       RETURN(rc);
+               }
+               cnt = 0;
+       }
+
+       if (!(lr->lr_flags & LEF_TO_OST) &&
+           list_empty(&llmd->llmd_mdt_phase1_list))
+               goto again;
+
+       ptlrpc_set_destroy(set);
+
+       RETURN(rc1 != 0 ? rc1 : rc);
+}
+
+static inline bool
+lfsck_layout_master_to_orphan(struct lfsck_layout_master_data *llmd)
+{
+       return list_empty(&llmd->llmd_mdt_phase1_list) &&
+              (!list_empty(&llmd->llmd_ost_phase2_list) ||
+               list_empty(&llmd->llmd_ost_phase1_list));
+}
+
+static int lfsck_layout_master_notify_others(const struct lu_env *env,
+                                            struct lfsck_component *com,
+                                            struct lfsck_request *lr,
+                                            __u32 flags)
+{
+       struct lfsck_thread_info          *info  = lfsck_env_info(env);
+       struct lfsck_async_interpret_args *laia  = &info->lti_laia;
+       struct lfsck_instance             *lfsck = com->lc_lfsck;
+       struct lfsck_layout_master_data   *llmd  = com->lc_data;
+       struct lfsck_layout               *lo    = com->lc_file_ram;
+       struct ptlrpc_request_set         *set;
+       struct lfsck_tgt_descs            *ltds;
+       struct lfsck_tgt_desc             *ltd;
+       struct lfsck_tgt_desc             *next;
+       struct list_head                  *head;
+       __u32                              idx;
+       __u32                              cnt   = 0;
+       int                                rc    = 0;
+       ENTRY;
+
+       set = ptlrpc_prep_set();
+       if (set == NULL)
+               RETURN(-ENOMEM);
+
+       lr->lr_active = LT_LAYOUT;
+       laia->laia_com = com;
+       laia->laia_lr = lr;
+       lr->lr_flags = 0;
+       switch (lr->lr_event) {
+       case LE_START:
+               /* Notify OSTs firstly, then other MDTs if needed. */
+               lr->lr_flags |= LEF_TO_OST;
+               ltds = &lfsck->li_ost_descs;
+
+lable1:
+               laia->laia_ltds = ltds;
+               down_read(&ltds->ltd_rw_sem);
+               cfs_foreach_bit(ltds->ltd_tgts_bitmap, idx) {
+                       ltd = lfsck_tgt_get(ltds, idx);
+                       LASSERT(ltd != NULL);
+
+                       laia->laia_ltd = ltd;
+                       ltd->ltd_layout_done = 0;
+                       rc = lfsck_async_request(env, ltd->ltd_exp, lr, set,
+                                       lfsck_layout_master_async_interpret,
+                                       laia, LFSCK_NOTIFY);
+                       if (rc != 0) {
+                               CERROR("%s: fail to notify %s %x for layout "
+                                      "start: rc = %d\n",
+                                      lfsck_lfsck2name(lfsck),
+                                      (lr->lr_flags & LEF_TO_OST) ? "OST" :
+                                      "MDT", idx, rc);
+                               lfsck_tgt_put(ltd);
+                               lo->ll_flags |= LF_INCOMPLETE;
+                       } else {
+                               cnt++;
+                       }
+               }
+               up_read(&ltds->ltd_rw_sem);
+
+               /* Sync up */
+               if (cnt > 0) {
+                       rc = ptlrpc_set_wait(set);
+                       if (rc < 0) {
+                               ptlrpc_set_destroy(set);
+                               RETURN(rc);
+                       }
+                       cnt = 0;
+               }
+
+               if (!(flags & LPF_ALL_MDT))
+                       break;
+
+               ltds = &lfsck->li_mdt_descs;
+               /* The sponsor broadcasts the request to other MDTs. */
+               if (flags & LPF_BROADCAST) {
+                       flags &= ~LPF_ALL_MDT;
+                       lr->lr_flags &= ~LEF_TO_OST;
+                       goto lable1;
+               }
+
+               /* non-sponsors link other MDT targets locallly. */
+               spin_lock(&ltds->ltd_lock);
+               cfs_foreach_bit(ltds->ltd_tgts_bitmap, idx) {
+                       ltd = LTD_TGT(ltds, idx);
+                       LASSERT(ltd != NULL);
+
+                       if (!list_empty(&ltd->ltd_layout_list))
+                               continue;
+
+                       list_add_tail(&ltd->ltd_layout_list,
+                                     &llmd->llmd_mdt_list);
+                       list_add_tail(&ltd->ltd_layout_phase_list,
+                                     &llmd->llmd_mdt_phase1_list);
+               }
+               spin_unlock(&ltds->ltd_lock);
+
+               break;
+       case LE_STOP:
+               if (flags & LPF_BROADCAST)
+                       lr->lr_flags |= LEF_FORCE_STOP;
+       case LE_PHASE2_DONE:
+               /* Notify other MDTs if needed, then the OSTs. */
+               if (flags & LPF_ALL_MDT) {
+                       /* The sponsor broadcasts the request to other MDTs. */
+                       if (flags & LPF_BROADCAST) {
+                               lr->lr_flags &= ~LEF_TO_OST;
+                               head = &llmd->llmd_mdt_list;
+                               ltds = &lfsck->li_mdt_descs;
+                               goto lable3;
+                       }
+
+                       /* non-sponsors unlink other MDT targets locallly. */
+                       ltds = &lfsck->li_mdt_descs;
+                       spin_lock(&ltds->ltd_lock);
+                       list_for_each_entry_safe(ltd, next,
+                                                &llmd->llmd_mdt_list,
+                                                ltd_layout_list) {
+                               list_del_init(&ltd->ltd_layout_phase_list);
+                               list_del_init(&ltd->ltd_layout_list);
+                       }
+                       spin_unlock(&ltds->ltd_lock);
+               }
+
+lable2:
+               lr->lr_flags |= LEF_TO_OST;
+               head = &llmd->llmd_ost_list;
+               ltds = &lfsck->li_ost_descs;
+
+lable3:
+               laia->laia_ltds = ltds;
+               spin_lock(&ltds->ltd_lock);
+               while (!list_empty(head)) {
+                       ltd = list_entry(head->next, struct lfsck_tgt_desc,
+                                        ltd_layout_list);
+                       if (!list_empty(&ltd->ltd_layout_phase_list))
+                               list_del_init(&ltd->ltd_layout_phase_list);
+                       list_del_init(&ltd->ltd_layout_list);
+                       laia->laia_ltd = ltd;
+                       spin_unlock(&ltds->ltd_lock);
+                       rc = lfsck_async_request(env, ltd->ltd_exp, lr, set,
+                                       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",
+                                      lfsck_lfsck2name(lfsck),
+                                      (lr->lr_flags & LEF_TO_OST) ? "OST" :
+                                      "MDT", ltd->ltd_index, rc);
+                       else
+                               cnt++;
+                       spin_lock(&ltds->ltd_lock);
+               }
+               spin_unlock(&ltds->ltd_lock);
+
+               if (!(flags & LPF_BROADCAST))
+                       break;
+
+               /* Sync up */
+               if (cnt > 0) {
+                       rc = ptlrpc_set_wait(set);
+                       if (rc < 0) {
+                               ptlrpc_set_destroy(set);
+                               RETURN(rc);
+                       }
+                       cnt = 0;
+               }
+
+               flags &= ~LPF_BROADCAST;
+               goto lable2;
+       case LE_PHASE1_DONE:
+               llmd->llmd_touch_gen++;
+               lr->lr_flags &= ~LEF_TO_OST;
+               ltds = &lfsck->li_mdt_descs;
+               laia->laia_ltds = ltds;
+               spin_lock(&ltds->ltd_lock);
+               while (!list_empty(&llmd->llmd_mdt_phase1_list)) {
+                       ltd = list_entry(llmd->llmd_mdt_phase1_list.next,
+                                        struct lfsck_tgt_desc,
+                                        ltd_layout_phase_list);
+                       if (ltd->ltd_layout_gen == llmd->llmd_touch_gen)
+                               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);
+                       laia->laia_ltd = ltd;
+                       spin_unlock(&ltds->ltd_lock);
+                       rc = lfsck_async_request(env, ltd->ltd_exp, lr, set,
+                                       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),
+                                      ltd->ltd_index, rc);
+                       else
+                               cnt++;
+                       spin_lock(&ltds->ltd_lock);
+               }
+               spin_unlock(&ltds->ltd_lock);
+               break;
+       default:
+               CERROR("%s: unexpected LFSCK event: rc = %d\n",
+                      lfsck_lfsck2name(lfsck), lr->lr_event);
+               rc = -EINVAL;
+               break;
+       }
+
+       if (cnt > 0)
+               rc = ptlrpc_set_wait(set);
+       ptlrpc_set_destroy(set);
+
+       if (rc == 0 && lr->lr_event == LE_START &&
+           list_empty(&llmd->llmd_ost_list))
+               rc = -ENODEV;
+
+       RETURN(rc);
+}
+
+static int lfsck_layout_double_scan_result(const struct lu_env *env,
+                                          struct lfsck_component *com,
+                                          int rc)
+{
+       struct lfsck_instance   *lfsck = com->lc_lfsck;
+       struct lfsck_layout     *lo    = com->lc_file_ram;
+       struct lfsck_bookmark   *bk    = &lfsck->li_bookmark_ram;
+
+       down_write(&com->lc_sem);
+
+       lo->ll_run_time_phase2 += cfs_duration_sec(cfs_time_current() +
+                               HALF_SEC - lfsck->li_time_last_checkpoint);
+       lo->ll_time_last_checkpoint = cfs_time_current_sec();
+       lo->ll_objs_checked_phase2 += com->lc_new_checked;
+
+       if (rc > 0) {
+               com->lc_journal = 0;
+               if (lo->ll_flags & LF_INCOMPLETE)
+                       lo->ll_status = LS_PARTIAL;
+               else
+                       lo->ll_status = LS_COMPLETED;
+               if (!(bk->lb_param & LPF_DRYRUN))
+                       lo->ll_flags &= ~(LF_SCANNED_ONCE | LF_INCONSISTENT);
+               lo->ll_time_last_complete = lo->ll_time_last_checkpoint;
+               lo->ll_success_count++;
+       } else if (rc == 0) {
+               lo->ll_status = lfsck->li_status;
+               if (lo->ll_status == 0)
+                       lo->ll_status = LS_STOPPED;
+       } else {
+               lo->ll_status = LS_FAILED;
+       }
+
+       if (lo->ll_status != LS_PAUSED) {
+               spin_lock(&lfsck->li_lock);
+               list_del_init(&com->lc_link);
+               list_add_tail(&com->lc_link, &lfsck->li_list_idle);
+               spin_unlock(&lfsck->li_lock);
+       }
+
+       rc = lfsck_layout_store(env, com);
+
+       up_write(&com->lc_sem);
+
+       return rc;
+}
+
+static int lfsck_layout_lock(const struct lu_env *env,
+                            struct lfsck_component *com,
+                            struct dt_object *obj,
+                            struct lustre_handle *lh, __u64 bits)
+{
+       struct lfsck_thread_info        *info   = lfsck_env_info(env);
+       ldlm_policy_data_t              *policy = &info->lti_policy;
+       struct ldlm_res_id              *resid  = &info->lti_resid;
+       struct lfsck_instance           *lfsck  = com->lc_lfsck;
+       __u64                            flags  = LDLM_FL_ATOMIC_CB;
+       int                              rc;
+
+       LASSERT(lfsck->li_namespace != NULL);
+
+       memset(policy, 0, sizeof(*policy));
+       policy->l_inodebits.bits = bits;
+       fid_build_reg_res_name(lfsck_dto2fid(obj), resid);
+       rc = ldlm_cli_enqueue_local(lfsck->li_namespace, resid, LDLM_IBITS,
+                                   policy, LCK_EX, &flags, ldlm_blocking_ast,
+                                   ldlm_completion_ast, NULL, NULL, 0,
+                                   LVB_T_NONE, NULL, lh);
+       if (rc == ELDLM_OK) {
+               rc = 0;
+       } else {
+               memset(lh, 0, sizeof(*lh));
+               rc = -EIO;
+       }
+
+       return rc;
+}
+
+static void lfsck_layout_unlock(struct lustre_handle *lh)
+{
+       if (lustre_handle_is_used(lh)) {
+               ldlm_lock_decref(lh, LCK_EX);
+               memset(lh, 0, sizeof(*lh));
+       }
+}
+
+static int lfsck_layout_trans_stop(const struct lu_env *env,
+                                  struct dt_device *dev,
+                                  struct thandle *handle, int result)
+{
+       int rc;
+
+       handle->th_result = result;
+       rc = dt_trans_stop(env, dev, handle);
+       if (rc > 0)
+               rc = 0;
+       else if (rc == 0)
+               rc = 1;
+
+       return rc;
+}
+
+static int lfsck_layout_scan_orphan(const struct lu_env *env,
+                                   struct lfsck_component *com,
+                                   struct lfsck_tgt_desc *ltd)
+{
+       /* XXX: To be extended in other patch. */
+
+       return 0;
+}
+
+/* For the MDT-object with dangling reference, we need to re-create
+ * the missed OST-object with the known FID/owner information. */
+static int lfsck_layout_recreate_ostobj(const struct lu_env *env,
+                                       struct lfsck_component *com,
+                                       struct lfsck_layout_req *llr,
+                                       struct lu_attr *la)
+{
+       struct lfsck_thread_info        *info   = lfsck_env_info(env);
+       struct filter_fid               *pfid   = &info->lti_new_pfid;
+       struct dt_allocation_hint       *hint   = &info->lti_hint;
+       struct dt_object                *parent = llr->llr_parent->llo_obj;
+       struct dt_object                *child  = llr->llr_child;
+       struct dt_device                *dev    = lfsck_obj2dt_dev(child);
+       const struct lu_fid             *tfid   = lu_object_fid(&parent->do_lu);
+       struct thandle                  *handle;
+       struct lu_buf                   *buf;
+       struct lustre_handle             lh     = { 0 };
+       int                              rc;
+       ENTRY;
+
+       CDEBUG(D_LFSCK, "Repair dangling reference 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, 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);
+
+       handle = dt_trans_create(env, dev);
+       if (IS_ERR(handle))
+               GOTO(unlock1, rc = PTR_ERR(handle));
+
+       hint->dah_parent = NULL;
+       hint->dah_mode = 0;
+       pfid->ff_parent.f_seq = cpu_to_le64(tfid->f_seq);
+       pfid->ff_parent.f_oid = cpu_to_le32(tfid->f_oid);
+       pfid->ff_parent.f_ver = cpu_to_le32(llr->llr_lov_idx);
+       buf = lfsck_buf_get(env, pfid, sizeof(struct filter_fid));
+
+       rc = dt_declare_create(env, child, la, hint, NULL, handle);
+       if (rc != 0)
+               GOTO(stop, rc);
+
+       rc = dt_declare_xattr_set(env, child, buf, XATTR_NAME_FID,
+                                 LU_XATTR_CREATE, handle);
+       if (rc != 0)
+               GOTO(stop, rc);
+
+       rc = dt_trans_start(env, dev, handle);
+       if (rc != 0)
+               GOTO(stop, rc);
+
+       dt_read_lock(env, parent, 0);
+       if (unlikely(lu_object_is_dying(parent->do_lu.lo_header)))
+               GOTO(unlock2, rc = 1);
+
+       rc = dt_create(env, child, la, hint, NULL, handle);
+       if (rc != 0)
+               GOTO(unlock2, rc);
+
+       rc = dt_xattr_set(env, child, buf, XATTR_NAME_FID, LU_XATTR_CREATE,
+                         handle, BYPASS_CAPA);
+
+       GOTO(unlock2, rc);
+
+unlock2:
+       dt_read_unlock(env, parent);
+
+stop:
+       rc = lfsck_layout_trans_stop(env, dev, handle, rc);
+
+unlock1:
+       lfsck_layout_unlock(&lh);
+
+       return rc;
+}
+
+/* If the OST-object does not recognize the MDT-object as its parent, and
+ * there is no other MDT-object claims as its parent, then just trust the
+ * given MDT-object as its parent. So update the OST-object filter_fid. */
+static int lfsck_layout_repair_unmatched_pair(const struct lu_env *env,
+                                             struct lfsck_component *com,
+                                             struct lfsck_layout_req *llr,
+                                             const struct lu_attr *pla)
+{
+       struct lfsck_thread_info        *info   = lfsck_env_info(env);
+       struct filter_fid               *pfid   = &info->lti_new_pfid;
+       struct lu_attr                  *tla    = &info->lti_la3;
+       struct dt_object                *parent = llr->llr_parent->llo_obj;
+       struct dt_object                *child  = llr->llr_child;
+       struct dt_device                *dev    = lfsck_obj2dt_dev(child);
+       const struct lu_fid             *tfid   = lu_object_fid(&parent->do_lu);
+       struct thandle                  *handle;
+       struct lu_buf                   *buf;
+       struct lustre_handle             lh     = { 0 };
+       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);
+
+       handle = dt_trans_create(env, dev);
+       if (IS_ERR(handle))
+               GOTO(unlock1, rc = PTR_ERR(handle));
+
+       pfid->ff_parent.f_seq = cpu_to_le64(tfid->f_seq);
+       pfid->ff_parent.f_oid = cpu_to_le32(tfid->f_oid);
+       /* The ff_parent->f_ver is not the real parent fid->f_ver. Instead,
+        * it is the OST-object index in the parent MDT-object layout. */
+       pfid->ff_parent.f_ver = cpu_to_le32(llr->llr_lov_idx);
+       buf = lfsck_buf_get(env, pfid, sizeof(struct filter_fid));
+
+       rc = dt_declare_xattr_set(env, child, buf, XATTR_NAME_FID, 0, handle);
+       if (rc != 0)
+               GOTO(stop, rc);
+
+       tla->la_valid = LA_UID | LA_GID;
+       tla->la_uid = pla->la_uid;
+       tla->la_gid = pla->la_gid;
+       rc = dt_declare_attr_set(env, child, tla, handle);
+       if (rc != 0)
+               GOTO(stop, rc);
+
+       rc = dt_trans_start(env, dev, handle);
+       if (rc != 0)
+               GOTO(stop, rc);
+
+       dt_write_lock(env, parent, 0);
+       if (unlikely(lu_object_is_dying(parent->do_lu.lo_header)))
+               GOTO(unlock2, rc = 1);
+
+       rc = dt_xattr_set(env, child, buf, XATTR_NAME_FID, 0, handle,
+                         BYPASS_CAPA);
+       if (rc != 0)
+               GOTO(unlock2, rc);
+
+       /* Get the latest parent's owner. */
+       rc = dt_attr_get(env, parent, tla, BYPASS_CAPA);
+       if (rc != 0)
+               GOTO(unlock2, rc);
+
+       tla->la_valid = LA_UID | LA_GID;
+       rc = dt_attr_set(env, child, tla, handle, BYPASS_CAPA);
+
+       GOTO(unlock2, rc);
+
+unlock2:
+       dt_write_unlock(env, parent);
+
+stop:
+       rc = lfsck_layout_trans_stop(env, dev, handle, rc);
+
+unlock1:
+       lfsck_layout_unlock(&lh);
+
+       return rc;
+}
+
+/* If there are more than one MDT-objects claim as the OST-object's parent,
+ * and the OST-object only recognizes one of them, then we need to generate
+ * new OST-object(s) with new fid(s) for the non-recognized MDT-object(s). */
+static int lfsck_layout_repair_multiple_references(const struct lu_env *env,
+                                                  struct lfsck_component *com,
+                                                  struct lfsck_layout_req *llr,
+                                                  struct lu_attr *la,
+                                                  struct lu_buf *buf)
+{
+       struct lfsck_thread_info        *info   = lfsck_env_info(env);
+       struct dt_allocation_hint       *hint   = &info->lti_hint;
+       struct dt_object_format         *dof    = &info->lti_dof;
+       struct dt_device                *pdev   = com->lc_lfsck->li_next;
+       struct ost_id                   *oi     = &info->lti_oi;
+       struct dt_object                *parent = llr->llr_parent->llo_obj;
+       struct dt_device                *cdev   = lfsck_obj2dt_dev(llr->llr_child);
+       struct dt_object                *child  = NULL;
+       struct lu_device                *d      = &cdev->dd_lu_dev;
+       struct lu_object                *o      = NULL;
+       struct thandle                  *handle;
+       struct lov_mds_md_v1            *lmm;
+       struct lov_ost_data_v1          *objs;
+       struct lustre_handle             lh     = { 0 };
+       __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);
+
+       handle = dt_trans_create(env, pdev);
+       if (IS_ERR(handle))
+               GOTO(unlock1, rc = PTR_ERR(handle));
+
+       o = lu_object_anon(env, d, NULL);
+       if (IS_ERR(o))
+               GOTO(stop, rc = PTR_ERR(o));
+
+       child = container_of(o, struct dt_object, do_lu);
+       o = lu_object_locate(o->lo_header, d->ld_type);
+       if (unlikely(o == NULL))
+               GOTO(stop, rc = -EINVAL);
+
+       child = container_of(o, struct dt_object, do_lu);
+       la->la_valid = LA_UID | LA_GID;
+       hint->dah_parent = NULL;
+       hint->dah_mode = 0;
+       dof->dof_type = DFT_REGULAR;
+       rc = dt_declare_create(env, child, la, NULL, NULL, handle);
+       if (rc != 0)
+               GOTO(stop, rc);
+
+       rc = dt_declare_xattr_set(env, parent, buf, XATTR_NAME_LOV,
+                                 LU_XATTR_REPLACE, handle);
+       if (rc != 0)
+               GOTO(stop, rc);
+
+       rc = dt_trans_start(env, pdev, handle);
+       if (rc != 0)
+               GOTO(stop, rc);
+
+       dt_write_lock(env, parent, 0);
+       if (unlikely(lu_object_is_dying(parent->do_lu.lo_header)))
+               GOTO(unlock2, rc = 0);
+
+       rc = dt_xattr_get(env, parent, buf, XATTR_NAME_LOV, BYPASS_CAPA);
+       if (unlikely(rc == 0 || rc == -ENODATA || rc == -ERANGE))
+               GOTO(unlock2, rc = 0);
+
+       lmm = buf->lb_buf;
+       rc = lfsck_layout_verify_header(lmm);
+       if (rc != 0)
+               GOTO(unlock2, rc);
+
+       /* Someone change layout during the LFSCK, no need to repair then. */
+       if (le16_to_cpu(lmm->lmm_layout_gen) != llr->llr_parent->llo_gen)
+               GOTO(unlock2, rc = 0);
+
+       rc = dt_create(env, child, la, hint, dof, handle);
+       if (rc != 0)
+               GOTO(unlock2, rc);
+
+       /* 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. */
+       magic = le32_to_cpu(lmm->lmm_magic);
+       if (magic == LOV_MAGIC_V1) {
+               objs = &(lmm->lmm_objects[0]);
+       } else {
+               LASSERT(magic == LOV_MAGIC_V3);
+               objs = &((struct lov_mds_md_v3 *)lmm)->lmm_objects[0];
+       }
+
+       lmm->lmm_layout_gen = cpu_to_le16(llr->llr_parent->llo_gen + 1);
+       fid_to_ostid(lu_object_fid(&child->do_lu), oi);
+       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,
+                         LU_XATTR_REPLACE, handle, BYPASS_CAPA);
+
+       GOTO(unlock2, rc = (rc == 0 ? 1 : rc));
+
+unlock2:
+       dt_write_unlock(env, parent);
+
+stop:
+       if (child != NULL)
+               lu_object_put(env, &child->do_lu);
+
+       dt_trans_stop(env, pdev, handle);
+
+unlock1:
+       lfsck_layout_unlock(&lh);
+
+       return rc;
+}
+
+/* If the MDT-object and the OST-object have different owner information,
+ * then trust the MDT-object, because the normal chown/chgrp handle order
+ * is from MDT to OST, and it is possible that some chown/chgrp operation
+ * is partly done. */
+static int lfsck_layout_repair_owner(const struct lu_env *env,
+                                    struct lfsck_component *com,
+                                    struct lfsck_layout_req *llr,
+                                    struct lu_attr *pla)
+{
+       struct lfsck_thread_info        *info   = lfsck_env_info(env);
+       struct lu_attr                  *tla    = &info->lti_la3;
+       struct dt_object                *parent = llr->llr_parent->llo_obj;
+       struct dt_object                *child  = llr->llr_child;
+       struct dt_device                *dev    = lfsck_obj2dt_dev(child);
+       struct thandle                  *handle;
+       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));
+
+       tla->la_uid = pla->la_uid;
+       tla->la_gid = pla->la_gid;
+       tla->la_valid = LA_UID | LA_GID;
+       rc = dt_declare_attr_set(env, child, tla, handle);
+       if (rc != 0)
+               GOTO(stop, rc);
+
+       rc = dt_trans_start(env, dev, handle);
+       if (rc != 0)
+               GOTO(stop, rc);
+
+       /* 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)))
+               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);
+
+               GOTO(unlock, rc);
+       }
+
+       /* Some others chown/chgrp during the LFSCK, needs to do nothing. */
+       if (unlikely(tla->la_uid != pla->la_uid ||
+                    tla->la_gid != pla->la_gid))
+               GOTO(unlock, rc = 1);
+
+       tla->la_valid = LA_UID | LA_GID;
+       rc = dt_attr_set(env, child, tla, handle, BYPASS_CAPA);
+
+       GOTO(unlock, rc);
+
+unlock:
+       dt_read_unlock(env, parent);
+
+stop:
+       rc = lfsck_layout_trans_stop(env, dev, handle, rc);
+
+       return rc;
+}
+
+/* Check whether the OST-object correctly back points to the
+ * MDT-object (@parent) via the XATTR_NAME_FID xattr (@pfid). */
+static int lfsck_layout_check_parent(const struct lu_env *env,
+                                    struct lfsck_component *com,
+                                    struct dt_object *parent,
+                                    const struct lu_fid *pfid,
+                                    const struct lu_fid *cfid,
+                                    const struct lu_attr *pla,
+                                    const struct lu_attr *cla,
+                                    struct lfsck_layout_req *llr,
+                                    struct lu_buf *lov_ea, __u32 idx)
+{
+       struct lfsck_thread_info        *info   = lfsck_env_info(env);
+       struct lu_buf                   *buf    = &info->lti_big_buf;
+       struct dt_object                *tobj;
+       struct lov_mds_md_v1            *lmm;
+       struct lov_ost_data_v1          *objs;
+       int                              rc;
+       int                              i;
+       __u32                            magic;
+       __u16                            count;
+       ENTRY;
+
+       if (fid_is_zero(pfid)) {
+               /* client never wrote. */
+               if (cla->la_size == 0 && cla->la_blocks == 0) {
+                       if (unlikely(cla->la_uid != pla->la_uid ||
+                                    cla->la_gid != pla->la_gid))
+                               RETURN (LLIT_INCONSISTENT_OWNER);
+
+                       RETURN(0);
+               }
+
+               RETURN(LLIT_UNMATCHED_PAIR);
+       }
+
+       if (unlikely(!fid_is_sane(pfid)))
+               RETURN(LLIT_UNMATCHED_PAIR);
+
+       if (lu_fid_eq(pfid, lu_object_fid(&parent->do_lu))) {
+               if (llr->llr_lov_idx == idx)
+                       RETURN(0);
+
+               RETURN(LLIT_UNMATCHED_PAIR);
+       }
+
+       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))
+               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)
+               GOTO(out, rc = LLIT_UNMATCHED_PAIR);
+
+       if (rc < 0)
+               GOTO(out, rc);
+
+       lmm = buf->lb_buf;
+       rc = lfsck_layout_verify_header(lmm);
+       if (rc != 0)
+               GOTO(out, rc);
+
+       /* 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. */
+       magic = le32_to_cpu(lmm->lmm_magic);
+       if (magic == LOV_MAGIC_V1) {
+               objs = &(lmm->lmm_objects[0]);
+       } else {
+               LASSERT(magic == LOV_MAGIC_V3);
+               objs = &((struct lov_mds_md_v3 *)lmm)->lmm_objects[0];
+       }
+
+       count = le16_to_cpu(lmm->lmm_stripe_count);
+       for (i = 0; i < count; i++, objs++) {
+               struct lu_fid           *tfid   = &info->lti_fid2;
+               struct ost_id           *oi     = &info->lti_oi;
+
+               ostid_le_to_cpu(&objs->l_ost_oi, oi);
+               ostid_to_fid(tfid, oi, le32_to_cpu(objs->l_ost_idx));
+               if (lu_fid_eq(cfid, tfid)) {
+                       *lov_ea = *buf;
+
+                       GOTO(out, rc = LLIT_MULTIPLE_REFERENCED);
+               }
+       }
+
+       GOTO(out, rc = LLIT_UNMATCHED_PAIR);
+
+out:
+       lfsck_object_put(env, tobj);
+
+       return rc;
+}
+
+static int lfsck_layout_assistant_handle_one(const struct lu_env *env,
+                                            struct lfsck_component *com,
+                                            struct lfsck_layout_req *llr)
+{
+       struct lfsck_layout                  *lo     = com->lc_file_ram;
+       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 dt_object                     *parent = llr->llr_parent->llo_obj;
+       struct dt_object                     *child  = llr->llr_child;
+       struct lu_attr                       *pla    = &info->lti_la;
+       struct lu_attr                       *cla    = &info->lti_la2;
+       struct lfsck_instance                *lfsck  = com->lc_lfsck;
+       struct lfsck_bookmark                *bk     = &lfsck->li_bookmark_ram;
+       enum lfsck_layout_inconsistency_type  type   = LLIT_NONE;
+       __u32                                 idx    = 0;
+       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);
+
+               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))
+                       RETURN(0);
+
+               type = LLIT_DANGLING;
+               goto repair;
+       }
+
+       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);
+       if (unlikely(rc >= 0 && rc != sizeof(struct filter_fid_old) &&
+                    rc != sizeof(struct filter_fid))) {
+               type = LLIT_UNMATCHED_PAIR;
+               goto repair;
+       }
+
+       if (rc < 0 && rc != -ENODATA)
+               GOTO(out, rc);
+
+       if (rc == -ENODATA) {
+               fid_zero(pfid);
+       } else {
+               fid_le_to_cpu(pfid, &pea->ff_parent);
+               /* OST-object does not save parent FID::f_ver, instead,
+                * the OST-object index in the parent MDT-object layout
+                * EA reuses the pfid->f_ver. */
+               idx = pfid->f_ver;
+               pfid->f_ver = 0;
+       }
+
+       rc = lfsck_layout_check_parent(env, com, parent, pfid,
+                                      lu_object_fid(&child->do_lu),
+                                      pla, cla, llr, buf, idx);
+       if (rc > 0) {
+               type = rc;
+               goto repair;
+       }
+
+       if (rc < 0)
+               GOTO(out, rc);
+
+       if (unlikely(cla->la_uid != pla->la_uid ||
+                    cla->la_gid != pla->la_gid)) {
+               type = LLIT_INCONSISTENT_OWNER;
+               goto repair;
+       }
+
+repair:
+       if (bk->lb_param & LPF_DRYRUN) {
+               if (type != LLIT_NONE)
+                       GOTO(out, rc = 1);
+               else
+                       GOTO(out, rc = 0);
+       }
+
+       switch (type) {
+       case LLIT_DANGLING:
+               memset(cla, 0, sizeof(*cla));
+               cla->la_uid = pla->la_uid;
+               cla->la_gid = pla->la_gid;
+               cla->la_mode = S_IFREG | 0666;
+               cla->la_valid = LA_TYPE | LA_MODE | LA_UID | LA_GID |
+                               LA_ATIME | LA_MTIME | LA_CTIME;
+               rc = lfsck_layout_recreate_ostobj(env, com, llr, cla);
+               break;
+       case LLIT_UNMATCHED_PAIR:
+               rc = lfsck_layout_repair_unmatched_pair(env, com, llr, pla);
+               break;
+       case LLIT_MULTIPLE_REFERENCED:
+               rc = lfsck_layout_repair_multiple_references(env, com, llr,
+                                                            pla, buf);
+               break;
+       case LLIT_INCONSISTENT_OWNER:
+               rc = lfsck_layout_repair_owner(env, com, llr, pla);
+               break;
+       default:
+               rc = 0;
+               break;
+       }
+
+       GOTO(out, rc);
+
+out:
+       down_write(&com->lc_sem);
+       if (rc < 0) {
+               /* If cannot touch the target server,
+                * mark the LFSCK as INCOMPLETE. */
+               if (rc == -ENOTCONN || rc == -ESHUTDOWN || rc == -ETIMEDOUT ||
+                   rc == -EHOSTDOWN || rc == -EHOSTUNREACH) {
+                       lo->ll_flags |= LF_INCOMPLETE;
+                       lo->ll_objs_skipped++;
+                       rc = 0;
+               } else {
+                       lo->ll_objs_failed_phase1++;
+               }
+       } else if (rc > 0) {
+               LASSERTF(type > LLIT_NONE && type <= LLIT_MAX,
+                        "unknown type = %d\n", type);
+
+               lo->ll_objs_repaired[type - 1]++;
+       }
+       up_write(&com->lc_sem);
+
+       return rc;
+}
+
+static int lfsck_layout_assistant(void *args)
+{
+       struct lfsck_thread_args        *lta     = args;
+       struct lu_env                   *env     = &lta->lta_env;
+       struct lfsck_component          *com     = lta->lta_com;
+       struct lfsck_instance           *lfsck   = lta->lta_lfsck;
+       struct lfsck_bookmark           *bk      = &lfsck->li_bookmark_ram;
+       struct lfsck_position           *pos     = &com->lc_pos_start;
+       struct lfsck_thread_info        *info    = lfsck_env_info(env);
+       struct lfsck_request            *lr      = &info->lti_lr;
+       struct lfsck_layout_master_data *llmd    = com->lc_data;
+       struct ptlrpc_thread            *mthread = &lfsck->li_thread;
+       struct ptlrpc_thread            *athread = &llmd->llmd_thread;
+       struct lfsck_layout_req         *llr;
+       struct l_wait_info               lwi     = { 0 };
+       int                              rc      = 0;
+       int                              rc1     = 0;
+       __u32                            flags;
+       ENTRY;
+
+       if (lta->lta_lsp->lsp_start != NULL)
+               flags  = lta->lta_lsp->lsp_start->ls_flags;
+       else
+               flags = bk->lb_param;
+       memset(lr, 0, sizeof(*lr));
+       lr->lr_event = LE_START;
+       lr->lr_index = lfsck_dev_idx(lfsck->li_bottom);
+       lr->lr_valid = LSV_SPEED_LIMIT | LSV_ERROR_HANDLE | LSV_DRYRUN |
+                      LSV_ASYNC_WINDOWS;
+       lr->lr_speed = bk->lb_speed_limit;
+       lr->lr_version = bk->lb_version;
+       lr->lr_param = bk->lb_param;
+       lr->lr_async_windows = bk->lb_async_windows;
+       if (pos->lp_oit_cookie <= 1)
+               lr->lr_param |= LPF_RESET;
+
+       rc = lfsck_layout_master_notify_others(env, com, lr, flags);
+       if (rc != 0) {
+               CERROR("%s: fail to notify others for layout start: rc = %d\n",
+                      lfsck_lfsck2name(lfsck), rc);
+               GOTO(fini, rc);
+       }
+
+       spin_lock(&llmd->llmd_lock);
+       thread_set_flags(athread, SVC_RUNNING);
+       spin_unlock(&llmd->llmd_lock);
+       wake_up_all(&mthread->t_ctl_waitq);
+
+       while (1) {
+               while (!list_empty(&llmd->llmd_req_list)) {
+                       bool wakeup = false;
+
+                       if (unlikely(llmd->llmd_exit))
+                               GOTO(cleanup1, rc = llmd->llmd_post_result);
+
+                       llr = list_entry(llmd->llmd_req_list.next,
+                                        struct lfsck_layout_req,
+                                        llr_list);
+                       /* Only the lfsck_layout_assistant thread itself can
+                        * remove the "llr" from the head of the list, LFSCK
+                        * engine thread only inserts other new "lld" at the
+                        * end of the list. So it is safe to handle current
+                        * "llr" without the spin_lock. */
+                       rc = lfsck_layout_assistant_handle_one(env, com, llr);
+                       spin_lock(&llmd->llmd_lock);
+                       list_del_init(&llr->llr_list);
+                       if (bk->lb_async_windows != 0 &&
+                           llmd->llmd_prefetched >= bk->lb_async_windows)
+                               wakeup = true;
+
+                       llmd->llmd_prefetched--;
+                       spin_unlock(&llmd->llmd_lock);
+                       if (wakeup)
+                               wake_up_all(&mthread->t_ctl_waitq);
+
+                       lfsck_layout_req_fini(env, llr);
+                       if (rc < 0 && bk->lb_param & LPF_FAILOUT)
+                               GOTO(cleanup1, rc);
+               }
+
+               /* Wakeup the master engine if it is waiting in checkpoint. */
+               wake_up_all(&mthread->t_ctl_waitq);
+
+               l_wait_event(athread->t_ctl_waitq,
+                            !lfsck_layout_req_empty(llmd) ||
+                            llmd->llmd_exit ||
+                            llmd->llmd_to_post ||
+                            llmd->llmd_to_double_scan,
+                            &lwi);
+
+               if (unlikely(llmd->llmd_exit))
+                       GOTO(cleanup1, rc = llmd->llmd_post_result);
+
+               if (!list_empty(&llmd->llmd_req_list))
+                       continue;
+
+               if (llmd->llmd_to_post) {
+                       llmd->llmd_to_post = 0;
+                       LASSERT(llmd->llmd_post_result > 0);
+
+                       memset(lr, 0, sizeof(*lr));
+                       lr->lr_index = lfsck_dev_idx(lfsck->li_bottom);
+                       lr->lr_event = LE_PHASE1_DONE;
+                       lr->lr_status = llmd->llmd_post_result;
+                       rc = lfsck_layout_master_notify_others(env, com, lr, 0);
+                       if (rc != 0)
+                               CERROR("%s: failed to notify others "
+                                      "for layout post: rc = %d\n",
+                                      lfsck_lfsck2name(lfsck), rc);
+
+                       /* Wakeup the master engine to go ahead. */
+                       wake_up_all(&mthread->t_ctl_waitq);
+               }
+
+               if (llmd->llmd_to_double_scan) {
+                       llmd->llmd_to_double_scan = 0;
+                       atomic_inc(&lfsck->li_double_scan_count);
+                       llmd->llmd_in_double_scan = 1;
+                       wake_up_all(&mthread->t_ctl_waitq);
+
+                       while (llmd->llmd_in_double_scan) {
+                               struct lfsck_tgt_descs  *ltds =
+                                                       &lfsck->li_ost_descs;
+                               struct lfsck_tgt_desc   *ltd;
+
+                               rc = lfsck_layout_master_query_others(env, com);
+                               if (lfsck_layout_master_to_orphan(llmd))
+                                       goto orphan;
+
+                               if (rc < 0)
+                                       GOTO(cleanup2, rc);
+
+                               /* Pull LFSCK status on related targets once
+                                * per 30 seconds if we are not notified. */
+                               lwi = LWI_TIMEOUT_INTERVAL(cfs_time_seconds(30),
+                                                          cfs_time_seconds(1),
+                                                          NULL, NULL);
+                               rc = l_wait_event(athread->t_ctl_waitq,
+                                       lfsck_layout_master_to_orphan(llmd) ||
+                                       llmd->llmd_exit ||
+                                       !thread_is_running(mthread),
+                                       &lwi);
+
+                               if (unlikely(llmd->llmd_exit ||
+                                            !thread_is_running(mthread)))
+                                       GOTO(cleanup2, rc = 0);
+
+                               if (rc == -ETIMEDOUT)
+                                       continue;
+
+                               if (rc < 0)
+                                       GOTO(cleanup2, rc);
+
+orphan:
+                               spin_lock(&ltds->ltd_lock);
+                               while (!list_empty(
+                                               &llmd->llmd_ost_phase2_list)) {
+                                       ltd = list_entry(
+                                             llmd->llmd_ost_phase2_list.next,
+                                             struct lfsck_tgt_desc,
+                                             ltd_layout_phase_list);
+                                       list_del_init(
+                                               &ltd->ltd_layout_phase_list);
+                                       spin_unlock(&ltds->ltd_lock);
+
+                                       rc = lfsck_layout_scan_orphan(env, com,
+                                                                     ltd);
+                                       if (rc != 0 &&
+                                           bk->lb_param & LPF_FAILOUT)
+                                               GOTO(cleanup2, rc);
+
+                                       if (unlikely(llmd->llmd_exit ||
+                                               !thread_is_running(mthread)))
+                                               GOTO(cleanup2, rc = 0);
+
+                                       spin_lock(&ltds->ltd_lock);
+                               }
+
+                               if (list_empty(&llmd->llmd_ost_phase1_list)) {
+                                       spin_unlock(&ltds->ltd_lock);
+                                       GOTO(cleanup2, rc = 1);
+                               }
+                               spin_unlock(&ltds->ltd_lock);
+                       }
+               }
+       }
+
+cleanup1:
+       /* Cleanup the unfinished requests. */
+       spin_lock(&llmd->llmd_lock);
+       if (rc < 0)
+               llmd->llmd_assistant_status = rc;
+
+       while (!list_empty(&llmd->llmd_req_list)) {
+               llr = list_entry(llmd->llmd_req_list.next,
+                                struct lfsck_layout_req,
+                                llr_list);
+               list_del_init(&llr->llr_list);
+               llmd->llmd_prefetched--;
+               spin_unlock(&llmd->llmd_lock);
+               lfsck_layout_req_fini(env, llr);
+               spin_lock(&llmd->llmd_lock);
+       }
+       spin_unlock(&llmd->llmd_lock);
+
+       LASSERTF(llmd->llmd_prefetched == 0, "unmatched prefeteched objs %d\n",
+                llmd->llmd_prefetched);
+
+cleanup2:
+       memset(lr, 0, sizeof(*lr));
+       lr->lr_index = lfsck_dev_idx(lfsck->li_bottom);
+       if (rc > 0) {
+               lr->lr_event = LE_PHASE2_DONE;
+               flags = 0;
+               lr->lr_status = rc;
+       } else if (rc == 0) {
+               lr->lr_event = LE_STOP;
+               if (lfsck->li_status == LS_PAUSED ||
+                   lfsck->li_status == LS_CO_PAUSED) {
+                       flags = 0;
+                       lr->lr_status = LS_CO_PAUSED;
+               } else if (lfsck->li_status == LS_STOPPED ||
+                        lfsck->li_status == LS_CO_STOPPED) {
+                       flags = lfsck->li_flags;
+                       if (flags & LPF_BROADCAST)
+                               lr->lr_status = LS_STOPPED;
+                       else
+                               lr->lr_status = LS_CO_STOPPED;
+               } else {
+                       LBUG();
+               }
+       } else {
+               lr->lr_event = LE_STOP;
+               flags = 0;
+               lr->lr_status = LS_CO_FAILED;
+       }
+
+       rc1 = lfsck_layout_master_notify_others(env, com, lr, flags);
+       if (rc1 != 0) {
+               CERROR("%s: failed to notify others for layout quit: rc = %d\n",
+                      lfsck_lfsck2name(lfsck), rc1);
+               rc = rc1;
+       }
+
+       /* 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_exit)
+               rc1 = lfsck_layout_double_scan_result(env, com, rc);
+
+fini:
+       if (llmd->llmd_in_double_scan)
+               atomic_dec(&lfsck->li_double_scan_count);
+
+       spin_lock(&llmd->llmd_lock);
+       llmd->llmd_assistant_status = (rc1 != 0 ? rc1 : rc);
+       thread_set_flags(athread, SVC_STOPPED);
+       wake_up_all(&mthread->t_ctl_waitq);
+       spin_unlock(&llmd->llmd_lock);
+       lfsck_thread_args_fini(lta);
+
+       return rc;
+}
+
+static int
+lfsck_layout_slave_async_interpret(const struct lu_env *env,
+                                  struct ptlrpc_request *req,
+                                  void *args, int rc)
+{
+       struct lfsck_layout_slave_async_args *llsaa = args;
+       struct obd_export                    *exp   = llsaa->llsaa_exp;
+       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;
+       bool                                  done  = false;
+
+       if (rc != 0) {
+               /* It is quite probably caused by target crash,
+                * to make the LFSCK can go ahead, assume that
+                * 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)
+               lfsck_layout_llst_del(llsd, llst);
+       lfsck_layout_llst_put(llst);
+       lfsck_component_put(env, com);
+       class_export_put(exp);
+
+       return 0;
+}
+
+static int lfsck_layout_async_query(const struct lu_env *env,
+                                   struct lfsck_component *com,
+                                   struct obd_export *exp,
+                                   struct lfsck_layout_slave_target *llst,
+                                   struct lfsck_request *lr,
+                                   struct ptlrpc_request_set *set)
+{
+       struct lfsck_layout_slave_async_args *llsaa;
+       struct ptlrpc_request                *req;
+       struct lfsck_request                 *tmp;
+       int                                   rc;
+       ENTRY;
+
+       req = ptlrpc_request_alloc(class_exp2cliimp(exp), &RQF_LFSCK_QUERY);
+       if (req == NULL)
+               RETURN(-ENOMEM);
+
+       rc = ptlrpc_request_pack(req, LUSTRE_OBD_VERSION, LFSCK_QUERY);
+       if (rc != 0) {
+               ptlrpc_request_free(req);
+               RETURN(rc);
+       }
+
+       tmp = req_capsule_client_get(&req->rq_pill, &RMF_LFSCK_REQUEST);
+       *tmp = *lr;
+       ptlrpc_request_set_replen(req);
+
+       llsaa = ptlrpc_req_async_args(req);
+       llsaa->llsaa_exp = exp;
+       llsaa->llsaa_com = lfsck_component_get(com);
+       llsaa->llsaa_llst = llst;
+       req->rq_interpret_reply = lfsck_layout_slave_async_interpret;
+       ptlrpc_set_add_req(set, req);
+
+       RETURN(0);
+}
+
+static int lfsck_layout_async_notify(const struct lu_env *env,
+                                    struct obd_export *exp,
+                                    struct lfsck_request *lr,
+                                    struct ptlrpc_request_set *set)
+{
+       struct ptlrpc_request   *req;
+       struct lfsck_request    *tmp;
+       int                      rc;
+       ENTRY;
+
+       req = ptlrpc_request_alloc(class_exp2cliimp(exp), &RQF_LFSCK_NOTIFY);
+       if (req == NULL)
+               RETURN(-ENOMEM);
+
+       rc = ptlrpc_request_pack(req, LUSTRE_OBD_VERSION, LFSCK_NOTIFY);
+       if (rc != 0) {
+               ptlrpc_request_free(req);
+               RETURN(rc);
+       }
+
+       tmp = req_capsule_client_get(&req->rq_pill, &RMF_LFSCK_REQUEST);
+       *tmp = *lr;
+       ptlrpc_request_set_replen(req);
+       ptlrpc_set_add_req(set, req);
+
+       RETURN(0);
+}
+
+static int
+lfsck_layout_slave_query_master(const struct lu_env *env,
+                               struct lfsck_component *com)
+{
+       struct lfsck_request             *lr    = &lfsck_env_info(env)->lti_lr;
+       struct lfsck_instance            *lfsck = com->lc_lfsck;
+       struct lfsck_layout_slave_data   *llsd  = com->lc_data;
+       struct lfsck_layout_slave_target *llst;
+       struct obd_export                *exp;
+       struct ptlrpc_request_set        *set;
+       int                               cnt   = 0;
+       int                               rc    = 0;
+       int                               rc1   = 0;
+       ENTRY;
+
+       set = ptlrpc_prep_set();
+       if (set == NULL)
+               RETURN(-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;
+
+       llsd->llsd_touch_gen++;
+       spin_lock(&llsd->llsd_lock);
+       while (!list_empty(&llsd->llsd_master_list)) {
+               llst = list_entry(llsd->llsd_master_list.next,
+                                 struct lfsck_layout_slave_target,
+                                 llst_list);
+               if (llst->llst_gen == llsd->llsd_touch_gen)
+                       break;
+
+               llst->llst_gen = llsd->llsd_touch_gen;
+               list_del(&llst->llst_list);
+               list_add_tail(&llst->llst_list,
+                             &llsd->llsd_master_list);
+               atomic_inc(&llst->llst_ref);
+               spin_unlock(&llsd->llsd_lock);
+
+               exp = lustre_find_lwp_by_index(lfsck->li_obd->obd_name,
+                                              llst->llst_index);
+               if (exp == NULL) {
+                       lfsck_layout_llst_del(llsd, llst);
+                       lfsck_layout_llst_put(llst);
+                       spin_lock(&llsd->llsd_lock);
+                       continue;
+               }
+
+               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),
+                              exp->exp_obd->obd_name, rc);
+                       rc1 = rc;
+                       lfsck_layout_llst_put(llst);
+                       class_export_put(exp);
+               } else {
+                       cnt++;
+               }
+               spin_lock(&llsd->llsd_lock);
+       }
+       spin_unlock(&llsd->llsd_lock);
+
+       if (cnt > 0)
+               rc = ptlrpc_set_wait(set);
+       ptlrpc_set_destroy(set);
+
+       RETURN(rc1 != 0 ? rc1 : rc);
+}
+
+static void
+lfsck_layout_slave_notify_master(const struct lu_env *env,
+                                struct lfsck_component *com,
+                                enum lfsck_events event, int result)
+{
+       struct lfsck_instance            *lfsck = com->lc_lfsck;
+       struct lfsck_layout_slave_data   *llsd  = com->lc_data;
+       struct lfsck_request             *lr    = &lfsck_env_info(env)->lti_lr;
+       struct lfsck_layout_slave_target *llst;
+       struct obd_export                *exp;
+       struct ptlrpc_request_set        *set;
+       int                               cnt   = 0;
+       int                               rc;
+       ENTRY;
+
+       set = ptlrpc_prep_set();
+       if (set == NULL)
+               RETURN_EXIT;
+
+       memset(lr, 0, sizeof(*lr));
+       lr->lr_event = event;
+       lr->lr_flags = LEF_FROM_OST;
+       lr->lr_status = result;
+       lr->lr_index = lfsck_dev_idx(lfsck->li_bottom);
+       lr->lr_active = LT_LAYOUT;
+       llsd->llsd_touch_gen++;
+       spin_lock(&llsd->llsd_lock);
+       while (!list_empty(&llsd->llsd_master_list)) {
+               llst = list_entry(llsd->llsd_master_list.next,
+                                 struct lfsck_layout_slave_target,
+                                 llst_list);
+               if (llst->llst_gen == llsd->llsd_touch_gen)
+                       break;
+
+               llst->llst_gen = llsd->llsd_touch_gen;
+               list_del(&llst->llst_list);
+               list_add_tail(&llst->llst_list,
+                             &llsd->llsd_master_list);
+               atomic_inc(&llst->llst_ref);
+               spin_unlock(&llsd->llsd_lock);
+
+               exp = lustre_find_lwp_by_index(lfsck->li_obd->obd_name,
+                                              llst->llst_index);
+               if (exp == NULL) {
+                       lfsck_layout_llst_del(llsd, llst);
+                       lfsck_layout_llst_put(llst);
+                       spin_lock(&llsd->llsd_lock);
+                       continue;
+               }
+
+               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),
+                              exp->exp_obd->obd_name, rc);
+               else
+                       cnt++;
+               lfsck_layout_llst_put(llst);
+               class_export_put(exp);
+               spin_lock(&llsd->llsd_lock);
+       }
+       spin_unlock(&llsd->llsd_lock);
+
+       if (cnt > 0)
+               rc = ptlrpc_set_wait(set);
+
+       ptlrpc_set_destroy(set);
+
+       RETURN_EXIT;
+}
+
+/* layout APIs */
+
+static int lfsck_layout_reset(const struct lu_env *env,
+                             struct lfsck_component *com, bool init)
+{
+       struct lfsck_layout     *lo    = com->lc_file_ram;
+       int                      rc;
+
+       down_write(&com->lc_sem);
+       if (init) {
+               memset(lo, 0, com->lc_file_size);
+       } else {
+               __u32 count = lo->ll_success_count;
+               __u64 last_time = lo->ll_time_last_complete;
+
+               memset(lo, 0, com->lc_file_size);
+               lo->ll_success_count = count;
+               lo->ll_time_last_complete = last_time;
+       }
+
+       lo->ll_magic = LFSCK_LAYOUT_MAGIC;
+       lo->ll_status = LS_INIT;
+
+       rc = lfsck_layout_store(env, com);
+       up_write(&com->lc_sem);
+
+       return rc;
+}
+
+static void lfsck_layout_fail(const struct lu_env *env,
+                             struct lfsck_component *com, bool new_checked)
+{
+       struct lfsck_layout *lo = com->lc_file_ram;
+
+       down_write(&com->lc_sem);
+       if (new_checked)
+               com->lc_new_checked++;
+       lo->ll_objs_failed_phase1++;
+       if (lo->ll_pos_first_inconsistent == 0) {
+               struct lfsck_instance *lfsck = com->lc_lfsck;
+
+               lo->ll_pos_first_inconsistent =
+                       lfsck->li_obj_oit->do_index_ops->dio_it.store(env,
+                                                       lfsck->li_di_oit);
+       }
+       up_write(&com->lc_sem);
+}
+
+static int lfsck_layout_master_checkpoint(const struct lu_env *env,
+                                         struct lfsck_component *com, bool init)
+{
+       struct lfsck_instance           *lfsck   = com->lc_lfsck;
+       struct lfsck_layout             *lo      = com->lc_file_ram;
+       struct lfsck_layout_master_data *llmd    = com->lc_data;
+       struct ptlrpc_thread            *mthread = &lfsck->li_thread;
+       struct ptlrpc_thread            *athread = &llmd->llmd_thread;
+       struct l_wait_info               lwi     = { 0 };
+       int                              rc;
+
+       if (com->lc_new_checked == 0 && !init)
+               return 0;
+
+       l_wait_event(mthread->t_ctl_waitq,
+                    list_empty(&llmd->llmd_req_list) ||
+                    !thread_is_running(mthread) ||
+                    thread_is_stopped(athread),
+                    &lwi);
+
+       if (!thread_is_running(mthread) || thread_is_stopped(athread))
+               return 0;
+
+       down_write(&com->lc_sem);
+       if (init) {
+               lo->ll_pos_latest_start = lfsck->li_pos_current.lp_oit_cookie;
+       } else {
+               lo->ll_pos_last_checkpoint =
+                                       lfsck->li_pos_current.lp_oit_cookie;
+               lo->ll_run_time_phase1 += cfs_duration_sec(cfs_time_current() +
+                               HALF_SEC - lfsck->li_time_last_checkpoint);
+               lo->ll_time_last_checkpoint = cfs_time_current_sec();
+               lo->ll_objs_checked_phase1 += com->lc_new_checked;
+               com->lc_new_checked = 0;
+       }
+
+       rc = lfsck_layout_store(env, com);
+       up_write(&com->lc_sem);
+
+       return rc;
+}
+
+static int lfsck_layout_slave_checkpoint(const struct lu_env *env,
+                                        struct lfsck_component *com, bool init)
+{
+       struct lfsck_instance   *lfsck = com->lc_lfsck;
+       struct lfsck_layout     *lo    = com->lc_file_ram;
+       int                      rc;
+
+       if (com->lc_new_checked == 0 && !init)
+               return 0;
+
+       down_write(&com->lc_sem);
+
+       if (init) {
+               lo->ll_pos_latest_start = lfsck->li_pos_current.lp_oit_cookie;
+       } else {
+               lo->ll_pos_last_checkpoint =
+                                       lfsck->li_pos_current.lp_oit_cookie;
+               lo->ll_run_time_phase1 += cfs_duration_sec(cfs_time_current() +
+                               HALF_SEC - lfsck->li_time_last_checkpoint);
+               lo->ll_time_last_checkpoint = cfs_time_current_sec();
+               lo->ll_objs_checked_phase1 += com->lc_new_checked;
+               com->lc_new_checked = 0;
+       }
+
+       rc = lfsck_layout_store(env, com);
+
+       up_write(&com->lc_sem);
+
+       return rc;
+}
+
+static int lfsck_layout_prep(const struct lu_env *env,
+                            struct lfsck_component *com)
+{
+       struct lfsck_instance   *lfsck  = com->lc_lfsck;
+       struct lfsck_layout     *lo     = com->lc_file_ram;
+       struct lfsck_position   *pos    = &com->lc_pos_start;
+
+       fid_zero(&pos->lp_dir_parent);
+       pos->lp_dir_cookie = 0;
+       if (lo->ll_status == LS_COMPLETED ||
+           lo->ll_status == LS_PARTIAL) {
+               int rc;
+
+               rc = lfsck_layout_reset(env, com, false);
+               if (rc != 0)
+                       return rc;
+       }
+
+       down_write(&com->lc_sem);
+
+       lo->ll_time_latest_start = cfs_time_current_sec();
+
+       spin_lock(&lfsck->li_lock);
+       if (lo->ll_flags & LF_SCANNED_ONCE) {
+               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);
+                       pos->lp_oit_cookie = 0;
+               } else {
+                       int i;
+
+                       lo->ll_status = LS_SCANNING_PHASE1;
+                       lo->ll_run_time_phase1 = 0;
+                       lo->ll_run_time_phase2 = 0;
+                       lo->ll_objs_checked_phase1 = 0;
+                       lo->ll_objs_checked_phase2 = 0;
+                       lo->ll_objs_failed_phase1 = 0;
+                       lo->ll_objs_failed_phase2 = 0;
+                       for (i = 0; i < LLIT_MAX; i++)
+                               lo->ll_objs_repaired[i] = 0;
+
+                       pos->lp_oit_cookie = lo->ll_pos_first_inconsistent;
+               }
+       } else {
+               lo->ll_status = LS_SCANNING_PHASE1;
+               if (!lfsck->li_drop_dryrun ||
+                   lo->ll_pos_first_inconsistent == 0)
+                       pos->lp_oit_cookie = lo->ll_pos_last_checkpoint + 1;
+               else
+                       pos->lp_oit_cookie = lo->ll_pos_first_inconsistent;
+       }
+       spin_unlock(&lfsck->li_lock);
+
+       up_write(&com->lc_sem);
+
+       return 0;
+}
+
+static int lfsck_layout_slave_prep(const struct lu_env *env,
+                                  struct lfsck_component *com,
+                                  struct lfsck_start_param *lsp)
+{
+       struct lfsck_layout             *lo     = com->lc_file_ram;
+       struct lfsck_layout_slave_data  *llsd   = com->lc_data;
+       int                              rc;
+
+       rc = lfsck_layout_prep(env, com);
+       if (rc != 0 || lo->ll_status != LS_SCANNING_PHASE1 ||
+           !lsp->lsp_index_valid)
+               return rc;
+
+       rc = lfsck_layout_llst_add(llsd, lsp->lsp_index);
+       if (rc == 0 && !(lo->ll_flags & LF_INCOMPLETE)) {
+               LASSERT(!llsd->llsd_rbtree_valid);
+
+               write_lock(&llsd->llsd_rb_lock);
+               rc = lfsck_rbtree_setup(env, com);
+               write_unlock(&llsd->llsd_rb_lock);
+       }
+
+       return rc;
+}
+
+static int lfsck_layout_master_prep(const struct lu_env *env,
+                                   struct lfsck_component *com,
+                                   struct lfsck_start_param *lsp)
+{
+       struct lfsck_instance           *lfsck   = com->lc_lfsck;
+       struct lfsck_layout_master_data *llmd    = com->lc_data;
+       struct ptlrpc_thread            *mthread = &lfsck->li_thread;
+       struct ptlrpc_thread            *athread = &llmd->llmd_thread;
+       struct lfsck_thread_args        *lta;
+       long                             rc;
+       ENTRY;
+
+       rc = lfsck_layout_prep(env, com);
+       if (rc != 0)
+               RETURN(rc);
+
+       llmd->llmd_assistant_status = 0;
+       llmd->llmd_post_result = 0;
+       llmd->llmd_to_post = 0;
+       llmd->llmd_to_double_scan = 0;
+       llmd->llmd_in_double_scan = 0;
+       llmd->llmd_exit = 0;
+       thread_set_flags(athread, 0);
+
+       lta = lfsck_thread_args_init(lfsck, com, lsp);
+       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);
+               lfsck_thread_args_fini(lta);
+       } else {
+               struct l_wait_info lwi = { 0 };
+
+               l_wait_event(mthread->t_ctl_waitq,
+                            thread_is_running(athread) ||
+                            thread_is_stopped(athread),
+                            &lwi);
+               if (unlikely(!thread_is_running(athread)))
+                       rc = llmd->llmd_assistant_status;
+               else
+                       rc = 0;
+       }
+
+       RETURN(rc);
+}
+
+/* Pre-fetch the attribute for each stripe in the given layout EA. */
+static int lfsck_layout_scan_stripes(const struct lu_env *env,
+                                    struct lfsck_component *com,
+                                    struct dt_object *parent,
+                                    struct lov_mds_md_v1 *lmm)
+{
+       struct lfsck_thread_info        *info    = lfsck_env_info(env);
+       struct lfsck_instance           *lfsck   = com->lc_lfsck;
+       struct lfsck_bookmark           *bk      = &lfsck->li_bookmark_ram;
+       struct lfsck_layout             *lo      = com->lc_file_ram;
+       struct lfsck_layout_master_data *llmd    = com->lc_data;
+       struct lfsck_layout_object      *llo     = NULL;
+       struct lov_ost_data_v1          *objs;
+       struct lfsck_tgt_descs          *ltds    = &lfsck->li_ost_descs;
+       struct ptlrpc_thread            *mthread = &lfsck->li_thread;
+       struct ptlrpc_thread            *athread = &llmd->llmd_thread;
+               struct l_wait_info       lwi     = { 0 };
+       struct lu_buf                   *buf;
+       int                              rc      = 0;
+       int                              i;
+       __u32                            magic;
+       __u16                            count;
+       __u16                            gen;
+       ENTRY;
+
+       buf = lfsck_buf_get(env, &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
+        * been verified in lfsck_layout_verify_header() already. If some
+        * new magic introduced in the future, then layout LFSCK needs to
+        * be updated also. */
+       magic = le32_to_cpu(lmm->lmm_magic);
+       if (magic == LOV_MAGIC_V1) {
+               objs = &(lmm->lmm_objects[0]);
+       } else {
+               LASSERT(magic == LOV_MAGIC_V3);
+               objs = &((struct lov_mds_md_v3 *)lmm)->lmm_objects[0];
+       }
+
+       for (i = 0; i < count; i++, objs++) {
+               struct lu_fid           *fid    = &info->lti_fid;
+               struct ost_id           *oi     = &info->lti_oi;
+               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);
+               bool                     wakeup = false;
+
+               l_wait_event(mthread->t_ctl_waitq,
+                            bk->lb_async_windows == 0 ||
+                            llmd->llmd_prefetched < bk->lb_async_windows ||
+                            !thread_is_running(mthread) ||
+                            thread_is_stopped(athread),
+                            &lwi);
+
+               if (unlikely(!thread_is_running(mthread)) ||
+                            thread_is_stopped(athread))
+                       GOTO(out, rc = 0);
+
+               ostid_le_to_cpu(&objs->l_ost_oi, oi);
+               ostid_to_fid(fid, oi, index);
+               tgt = lfsck_tgt_get(ltds, index);
+               if (unlikely(tgt == NULL)) {
+                       lo->ll_flags |= LF_INCOMPLETE;
+                       goto next;
+               }
+
+               cobj = lfsck_object_find_by_dev(env, tgt->ltd_tgt, fid);
+               if (IS_ERR(cobj)) {
+                       rc = PTR_ERR(cobj);
+                       goto next;
+               }
+
+               rc = dt_declare_attr_get(env, cobj, BYPASS_CAPA);
+               if (rc != 0)
+                       goto next;
+
+               rc = dt_declare_xattr_get(env, cobj, buf, XATTR_NAME_FID,
+                                         BYPASS_CAPA);
+               if (rc != 0)
+                       goto next;
+
+               if (llo == NULL) {
+                       llo = lfsck_layout_object_init(env, parent, gen);
+                       if (IS_ERR(llo)) {
+                               rc = PTR_ERR(llo);
+                               goto next;
+                       }
+               }
+
+               llr = lfsck_layout_req_init(llo, cobj, index, i);
+               if (IS_ERR(llr)) {
+                       rc = PTR_ERR(llr);
+                       goto next;
+               }
+
+               cobj = NULL;
+               spin_lock(&llmd->llmd_lock);
+               if (llmd->llmd_assistant_status < 0) {
+                       spin_unlock(&llmd->llmd_lock);
+                       lfsck_layout_req_fini(env, llr);
+                       lfsck_tgt_put(tgt);
+                       RETURN(llmd->llmd_assistant_status);
+               }
+
+               list_add_tail(&llr->llr_list, &llmd->llmd_req_list);
+               if (llmd->llmd_prefetched == 0)
+                       wakeup = true;
+
+               llmd->llmd_prefetched++;
+               spin_unlock(&llmd->llmd_lock);
+               if (wakeup)
+                       wake_up_all(&athread->t_ctl_waitq);
+
+next:
+               down_write(&com->lc_sem);
+               com->lc_new_checked++;
+               if (rc < 0)
+                       lo->ll_objs_failed_phase1++;
+               up_write(&com->lc_sem);
+
+               if (cobj != NULL && !IS_ERR(cobj))
+                       lu_object_put(env, &cobj->do_lu);
+
+               if (likely(tgt != NULL))
+                       lfsck_tgt_put(tgt);
+
+               if (rc < 0 && bk->lb_param & LPF_FAILOUT)
+                       GOTO(out, rc);
+       }
+
+       GOTO(out, rc = 0);
+
+out:
+       if (llo != NULL && !IS_ERR(llo))
+               lfsck_layout_object_put(env, llo);
+
+       return rc;
+}
+
+/* For the given object, read its layout EA locally. For each stripe, pre-fetch
+ * the OST-object's attribute and generate an structure lfsck_layout_req on the
+ * list ::llmd_req_list.
+ *
+ * For each request on above list, the lfsck_layout_assistant thread compares
+ * the OST side attribute with local attribute, if inconsistent, then repair it.
+ *
+ * All above processing is async mode with pipeline. */
+static int lfsck_layout_master_exec_oit(const struct lu_env *env,
+                                       struct lfsck_component *com,
+                                       struct dt_object *obj)
+{
+       struct lfsck_thread_info        *info   = lfsck_env_info(env);
+       struct ost_id                   *oi     = &info->lti_oi;
+       struct lfsck_layout             *lo     = com->lc_file_ram;
+       struct lfsck_layout_master_data *llmd   = com->lc_data;
+       struct lfsck_instance           *lfsck  = com->lc_lfsck;
+       struct lfsck_bookmark           *bk     = &lfsck->li_bookmark_ram;
+       struct thandle                  *handle = NULL;
+       struct lu_buf                   *buf    = &info->lti_big_buf;
+       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;
+       int                              rc     = 0;
+       bool                             locked = false;
+       bool                             stripe = false;
+       ENTRY;
+
+       if (!S_ISREG(lfsck_object_type(obj)))
+               GOTO(out, rc = 0);
+
+       if (llmd->llmd_assistant_status < 0)
+               GOTO(out, rc = -ESRCH);
+
+       fid_to_lmm_oi(lfsck_dto2fid(obj), oi);
+       lmm_oi_cpu_to_le(oi, oi);
+       dt_read_lock(env, obj, 0);
+       locked = true;
+
+again:
+       rc = lfsck_layout_get_lovea(env, obj, buf, &buflen);
+       if (rc <= 0)
+               GOTO(out, rc);
+
+       buf->lb_len = rc;
+       lmm = buf->lb_buf;
+       rc = lfsck_layout_verify_header(lmm);
+       if (rc != 0)
+               GOTO(out, rc);
+
+       if (memcmp(oi, &lmm->lmm_oi, sizeof(*oi)) == 0)
+               GOTO(out, stripe = true);
+
+       /* Inconsistent lmm_oi, should be repaired. */
+       CDEBUG(D_LFSCK, "Repair bad lmm_oi for "DFID"\n",
+              PFID(lfsck_dto2fid(obj)));
+
+       if (bk->lb_param & LPF_DRYRUN) {
+               down_write(&com->lc_sem);
+               lo->ll_objs_repaired[LLIT_OTHERS - 1]++;
+               up_write(&com->lc_sem);
+
+               GOTO(out, stripe = true);
+       }
+
+       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);
+               if (rc != 0)
+                       GOTO(out, rc);
+
+               handle = dt_trans_create(env, dev);
+               if (IS_ERR(handle))
+                       GOTO(out, rc = PTR_ERR(handle));
+
+               rc = dt_declare_xattr_set(env, obj, buf, XATTR_NAME_LOV,
+                                         LU_XATTR_REPLACE, handle);
+               if (rc != 0)
+                       GOTO(out, rc);
+
+               rc = dt_trans_start_local(env, dev, handle);
+               if (rc != 0)
+                       GOTO(out, rc);
+
+               dt_write_lock(env, obj, 0);
+               locked = true;
+
+               goto again;
+       }
+
+       lmm->lmm_oi = *oi;
+       rc = dt_xattr_set(env, obj, buf, XATTR_NAME_LOV,
+                         LU_XATTR_REPLACE, handle, BYPASS_CAPA);
+       if (rc != 0)
+               GOTO(out, rc);
+
+       down_write(&com->lc_sem);
+       lo->ll_objs_repaired[LLIT_OTHERS - 1]++;
+       up_write(&com->lc_sem);
+
+       GOTO(out, stripe = true);
+
+out:
+       if (locked) {
+               if (lustre_handle_is_used(&lh))
+                       dt_write_unlock(env, obj);
+               else
+                       dt_read_unlock(env, obj);
+       }
+
+       if (handle != NULL && !IS_ERR(handle))
+               dt_trans_stop(env, dev, handle);
+
+       lfsck_layout_unlock(&lh);
+       if (stripe) {
+               rc = lfsck_layout_scan_stripes(env, com, obj, lmm);
+       } else {
+               down_write(&com->lc_sem);
+               com->lc_new_checked++;
+               if (rc < 0)
+                       lo->ll_objs_failed_phase1++;
+               up_write(&com->lc_sem);
+       }
+       buf->lb_len = buflen;
+
+       return rc;
+}
+
+static int lfsck_layout_slave_exec_oit(const struct lu_env *env,
+                                      struct lfsck_component *com,
+                                      struct dt_object *obj)
+{
+       struct lfsck_instance           *lfsck  = com->lc_lfsck;
+       struct lfsck_layout             *lo     = com->lc_file_ram;
+       const struct lu_fid             *fid    = lfsck_dto2fid(obj);
+       struct lfsck_layout_slave_data  *llsd   = com->lc_data;
+       struct lfsck_layout_seq         *lls;
+       __u64                            seq;
+       __u64                            oid;
+       int                              rc;
+       ENTRY;
+
+       LASSERT(llsd != NULL);
+
+       lfsck_rbtree_update_bitmap(env, com, fid, false);
+
+       down_write(&com->lc_sem);
+       if (fid_is_idif(fid))
+               seq = 0;
+       else if (!fid_is_norm(fid) ||
+                !fid_is_for_ostobj(env, lfsck->li_next, obj, fid))
+               GOTO(unlock, rc = 0);
+       else
+               seq = fid_seq(fid);
+       com->lc_new_checked++;
+
+       lls = lfsck_layout_seq_lookup(llsd, seq);
+       if (lls == NULL) {
+               OBD_ALLOC_PTR(lls);
+               if (unlikely(lls == NULL))
+                       GOTO(unlock, rc = -ENOMEM);
+
+               INIT_LIST_HEAD(&lls->lls_list);
+               lls->lls_seq = seq;
+               rc = lfsck_layout_lastid_load(env, com, lls);
+               if (rc != 0) {
+                       lo->ll_objs_failed_phase1++;
+                       OBD_FREE_PTR(lls);
+                       GOTO(unlock, rc);
+               }
+
+               lfsck_layout_seq_insert(llsd, lls);
+       }
+
+       if (unlikely(fid_is_last_id(fid)))
+               GOTO(unlock, rc = 0);
+
+       oid = fid_oid(fid);
+       if (oid > lls->lls_lastid_known)
+               lls->lls_lastid_known = oid;
+
+       if (oid > lls->lls_lastid) {
+               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",
+                                     lfsck_lfsck2name(com->lc_lfsck),
+                                     lls->lls_seq, rc);
+                       if (oid <= lls->lls_lastid)
+                               GOTO(unlock, rc = 0);
+
+                       LASSERT(lfsck->li_out_notify != NULL);
+
+                       lfsck->li_out_notify(env, lfsck->li_out_notify_data,
+                                            LE_LASTID_REBUILDING);
+                       lo->ll_flags |= LF_CRASHED_LASTID;
+               }
+
+               lls->lls_lastid = oid;
+               lls->lls_dirty = 1;
+       }
+
+       GOTO(unlock, rc = 0);
+
+unlock:
+       up_write(&com->lc_sem);
+
+       return rc;
 }
 
 static int lfsck_layout_exec_dir(const struct lu_env *env,
@@ -292,56 +3400,754 @@ static int lfsck_layout_master_post(const struct lu_env *env,
                                    struct lfsck_component *com,
                                    int result, bool init)
 {
-       return 0;
+       struct lfsck_instance           *lfsck   = com->lc_lfsck;
+       struct lfsck_layout             *lo      = com->lc_file_ram;
+       struct lfsck_layout_master_data *llmd    = com->lc_data;
+       struct ptlrpc_thread            *mthread = &lfsck->li_thread;
+       struct ptlrpc_thread            *athread = &llmd->llmd_thread;
+       struct l_wait_info               lwi     = { 0 };
+       int                              rc;
+       ENTRY;
+
+
+       llmd->llmd_post_result = result;
+       llmd->llmd_to_post = 1;
+       if (llmd->llmd_post_result <= 0)
+               llmd->llmd_exit = 1;
+
+       wake_up_all(&athread->t_ctl_waitq);
+       l_wait_event(mthread->t_ctl_waitq,
+                    (result > 0 && list_empty(&llmd->llmd_req_list)) ||
+                    thread_is_stopped(athread),
+                    &lwi);
+
+       if (llmd->llmd_assistant_status < 0)
+               result = llmd->llmd_assistant_status;
+
+       down_write(&com->lc_sem);
+       spin_lock(&lfsck->li_lock);
+       /* When LFSCK failed, there may be some prefetched objects those are
+        * not been processed yet, we do not know the exactly position, then
+        * just restart from last check-point next time. */
+       if (!init && !llmd->llmd_exit)
+               lo->ll_pos_last_checkpoint =
+                                       lfsck->li_pos_current.lp_oit_cookie;
+
+       if (result > 0) {
+               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);
+       } 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);
+               }
+       } else {
+               lo->ll_status = LS_FAILED;
+               list_del_init(&com->lc_link);
+               list_add_tail(&com->lc_link, &lfsck->li_list_idle);
+       }
+       spin_unlock(&lfsck->li_lock);
+
+       if (!init) {
+               lo->ll_run_time_phase1 += cfs_duration_sec(cfs_time_current() +
+                               HALF_SEC - lfsck->li_time_last_checkpoint);
+               lo->ll_time_last_checkpoint = cfs_time_current_sec();
+               lo->ll_objs_checked_phase1 += com->lc_new_checked;
+               com->lc_new_checked = 0;
+       }
+
+       rc = lfsck_layout_store(env, com);
+       up_write(&com->lc_sem);
+
+       RETURN(rc);
 }
 
 static int lfsck_layout_slave_post(const struct lu_env *env,
                                   struct lfsck_component *com,
                                   int result, bool init)
 {
-       return 0;
+       struct lfsck_instance   *lfsck = com->lc_lfsck;
+       struct lfsck_layout     *lo    = com->lc_file_ram;
+       int                      rc;
+       bool                     done  = false;
+
+       rc = lfsck_layout_lastid_store(env, com);
+       if (rc != 0)
+               result = rc;
+
+       LASSERT(lfsck->li_out_notify != NULL);
+
+       down_write(&com->lc_sem);
+
+       spin_lock(&lfsck->li_lock);
+       if (!init)
+               lo->ll_pos_last_checkpoint =
+                                       lfsck->li_pos_current.lp_oit_cookie;
+       if (result > 0) {
+               lo->ll_status = LS_SCANNING_PHASE2;
+               lo->ll_flags |= LF_SCANNED_ONCE;
+               if (lo->ll_flags & LF_CRASHED_LASTID) {
+                       done = true;
+                       lo->ll_flags &= ~LF_CRASHED_LASTID;
+               }
+               lo->ll_flags &= ~LF_UPGRADE;
+               list_del_init(&com->lc_link);
+               list_add_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);
+               }
+       } else {
+               lo->ll_status = LS_FAILED;
+               list_del_init(&com->lc_link);
+               list_add_tail(&com->lc_link, &lfsck->li_list_idle);
+       }
+       spin_unlock(&lfsck->li_lock);
+
+       if (done)
+               lfsck->li_out_notify(env, lfsck->li_out_notify_data,
+                                    LE_LASTID_REBUILT);
+
+       if (!init) {
+               lo->ll_run_time_phase1 += cfs_duration_sec(cfs_time_current() +
+                               HALF_SEC - lfsck->li_time_last_checkpoint);
+               lo->ll_time_last_checkpoint = cfs_time_current_sec();
+               lo->ll_objs_checked_phase1 += com->lc_new_checked;
+               com->lc_new_checked = 0;
+       }
+
+       rc = lfsck_layout_store(env, com);
+
+       up_write(&com->lc_sem);
+
+       lfsck_layout_slave_notify_master(env, com, LE_PHASE1_DONE, result);
+
+       if (result <= 0)
+               lfsck_rbtree_cleanup(env, com);
+
+       return rc;
 }
 
 static int lfsck_layout_dump(const struct lu_env *env,
                             struct lfsck_component *com, char *buf, int len)
 {
-       return 0;
+       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"
+                     "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");
+       if (rc < 0)
+               goto out;
+
+       rc = lfsck_bits_dump(&buf, &len, bk->lb_param, lfsck_param_names,
+                            "param");
+       if (rc < 0)
+               goto out;
+
+       rc = lfsck_time_dump(&buf, &len, 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,
+                            "time_since_latest_start");
+       if (rc < 0)
+               goto out;
+
+       rc = lfsck_time_dump(&buf, &len, lo->ll_time_last_checkpoint,
+                            "time_since_last_checkpoint");
+       if (rc < 0)
+               goto out;
+
+       rc = snprintf(buf, len,
+                     "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"
+                     "repaired_dangling: "LPU64"\n"
+                     "repaired_unmatched_pair: "LPU64"\n"
+                     "repaired_multiple_referenced: "LPU64"\n"
+                     "repaired_orphan: "LPU64"\n"
+                     "repaired_inconsistent_owner: "LPU64"\n"
+                     "repaired_others: "LPU64"\n"
+                     "skipped: "LPU64"\n"
+                     "failed_phase1: "LPU64"\n"
+                     "failed_phase2: "LPU64"\n",
+                     lo->ll_success_count,
+                     lo->ll_objs_repaired[LLIT_DANGLING - 1],
+                     lo->ll_objs_repaired[LLIT_UNMATCHED_PAIR - 1],
+                     lo->ll_objs_repaired[LLIT_MULTIPLE_REFERENCED - 1],
+                     lo->ll_objs_repaired[LLIT_ORPHAN - 1],
+                     lo->ll_objs_repaired[LLIT_INCONSISTENT_OWNER - 1],
+                     lo->ll_objs_repaired[LLIT_OTHERS - 1],
+                     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;
+               const struct dt_it_ops *iops;
+               cfs_duration_t duration = cfs_time_current() -
+                                         lfsck->li_time_last_checkpoint;
+               __u64 checked = lo->ll_objs_checked_phase1 + com->lc_new_checked;
+               __u64 speed = checked;
+               __u64 new_checked = com->lc_new_checked * HZ;
+               __u32 rtime = lo->ll_run_time_phase1 +
+                             cfs_duration_sec(duration + HALF_SEC);
+
+               if (duration != 0)
+                       do_div(new_checked, duration);
+               if (rtime != 0)
+                       do_div(speed, 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: N/A\n"
+                             "real-time_speed_phase1: "LPU64" items/sec\n"
+                             "real-time_speed_phase2: N/A\n",
+                             checked,
+                             lo->ll_objs_checked_phase2,
+                             rtime,
+                             lo->ll_run_time_phase2,
+                             speed,
+                             new_checked);
+               if (rc <= 0)
+                       goto out;
+
+               buf += rc;
+               len -= rc;
+
+               LASSERT(lfsck->li_di_oit != NULL);
+
+               iops = &lfsck->li_obj_oit->do_index_ops->dio_it;
+
+               /* The low layer otable-based iteration position may NOT
+                * exactly match the layout-based directory traversal
+                * cookie. Generally, it is not a serious issue. But the
+                * caller should NOT make assumption on that. */
+               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;
+
+               buf += rc;
+               len -= rc;
+       } else {
+               /* XXX: LS_SCANNING_PHASE2 will be handled in the future. */
+               __u64 speed1 = lo->ll_objs_checked_phase1;
+               __u64 speed2 = lo->ll_objs_checked_phase2;
+
+               if (lo->ll_run_time_phase1 != 0)
+                       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;
+       }
+       ret = save - len;
+
+out:
+       up_read(&com->lc_sem);
+
+       return ret;
 }
 
 static int lfsck_layout_master_double_scan(const struct lu_env *env,
                                           struct lfsck_component *com)
 {
+       struct lfsck_layout_master_data *llmd    = com->lc_data;
+       struct ptlrpc_thread            *mthread = &com->lc_lfsck->li_thread;
+       struct ptlrpc_thread            *athread = &llmd->llmd_thread;
+       struct lfsck_layout             *lo      = com->lc_file_ram;
+       struct l_wait_info               lwi     = { 0 };
+
+       if (unlikely(lo->ll_status != LS_SCANNING_PHASE2))
+               return 0;
+
+       llmd->llmd_to_double_scan = 1;
+       wake_up_all(&athread->t_ctl_waitq);
+       l_wait_event(mthread->t_ctl_waitq,
+                    llmd->llmd_in_double_scan ||
+                    thread_is_stopped(athread),
+                    &lwi);
+       if (llmd->llmd_assistant_status < 0)
+               return llmd->llmd_assistant_status;
+
        return 0;
 }
 
 static int lfsck_layout_slave_double_scan(const struct lu_env *env,
                                          struct lfsck_component *com)
 {
-       return 0;
+       struct lfsck_instance           *lfsck  = com->lc_lfsck;
+       struct lfsck_layout_slave_data  *llsd   = com->lc_data;
+       struct lfsck_layout             *lo     = com->lc_file_ram;
+       struct ptlrpc_thread            *thread = &lfsck->li_thread;
+       int                              rc;
+       ENTRY;
+
+       if (unlikely(lo->ll_status != LS_SCANNING_PHASE2)) {
+               lfsck_rbtree_cleanup(env, com);
+               RETURN(0);
+       }
+
+       atomic_inc(&lfsck->li_double_scan_count);
+
+       com->lc_new_checked = 0;
+       com->lc_new_scanned = 0;
+       com->lc_time_last_checkpoint = cfs_time_current();
+       com->lc_time_next_checkpoint = com->lc_time_last_checkpoint +
+                               cfs_time_seconds(LFSCK_CHECKPOINT_INTERVAL);
+
+       while (1) {
+               struct l_wait_info lwi = LWI_TIMEOUT(cfs_time_seconds(30),
+                                                    NULL, NULL);
+
+               rc = lfsck_layout_slave_query_master(env, com);
+               if (list_empty(&llsd->llsd_master_list)) {
+                       if (unlikely(!thread_is_running(thread)))
+                               rc = 0;
+                       else
+                               rc = 1;
+
+                       GOTO(done, rc);
+               }
+
+               if (rc < 0)
+                       GOTO(done, rc);
+
+               rc = l_wait_event(thread->t_ctl_waitq,
+                                 !thread_is_running(thread) ||
+                                 list_empty(&llsd->llsd_master_list),
+                                 &lwi);
+               if (unlikely(!thread_is_running(thread)))
+                       GOTO(done, rc = 0);
+
+               if (rc == -ETIMEDOUT)
+                       continue;
+
+               GOTO(done, rc = (rc < 0 ? rc : 1));
+       }
+
+done:
+       rc = lfsck_layout_double_scan_result(env, com, rc);
+
+       lfsck_rbtree_cleanup(env, com);
+       if (atomic_dec_and_test(&lfsck->li_double_scan_count))
+               wake_up_all(&lfsck->li_thread.t_ctl_waitq);
+
+       return rc;
+}
+
+static void lfsck_layout_master_data_release(const struct lu_env *env,
+                                            struct lfsck_component *com)
+{
+       struct lfsck_layout_master_data *llmd   = com->lc_data;
+       struct lfsck_instance           *lfsck  = com->lc_lfsck;
+       struct lfsck_tgt_descs          *ltds;
+       struct lfsck_tgt_desc           *ltd;
+       struct lfsck_tgt_desc           *next;
+
+       LASSERT(llmd != NULL);
+       LASSERT(thread_is_init(&llmd->llmd_thread) ||
+               thread_is_stopped(&llmd->llmd_thread));
+       LASSERT(list_empty(&llmd->llmd_req_list));
+
+       com->lc_data = NULL;
+
+       ltds = &lfsck->li_ost_descs;
+       spin_lock(&ltds->ltd_lock);
+       list_for_each_entry_safe(ltd, next, &llmd->llmd_ost_phase1_list,
+                                ltd_layout_phase_list) {
+               list_del_init(&ltd->ltd_layout_phase_list);
+       }
+       list_for_each_entry_safe(ltd, next, &llmd->llmd_ost_phase2_list,
+                                ltd_layout_phase_list) {
+               list_del_init(&ltd->ltd_layout_phase_list);
+       }
+       list_for_each_entry_safe(ltd, next, &llmd->llmd_ost_list,
+                                ltd_layout_list) {
+               list_del_init(&ltd->ltd_layout_list);
+       }
+       list_for_each_entry_safe(ltd, next, &llmd->llmd_mdt_phase1_list,
+                                ltd_layout_phase_list) {
+               list_del_init(&ltd->ltd_layout_phase_list);
+       }
+       list_for_each_entry_safe(ltd, next, &llmd->llmd_mdt_phase2_list,
+                                ltd_layout_phase_list) {
+               list_del_init(&ltd->ltd_layout_phase_list);
+       }
+       list_for_each_entry_safe(ltd, next, &llmd->llmd_mdt_list,
+                                ltd_layout_list) {
+               list_del_init(&ltd->ltd_layout_list);
+       }
+       spin_unlock(&ltds->ltd_lock);
+
+       OBD_FREE_PTR(llmd);
+}
+
+static void lfsck_layout_slave_data_release(const struct lu_env *env,
+                                           struct lfsck_component *com)
+{
+       struct lfsck_layout_slave_data   *llsd  = com->lc_data;
+       struct lfsck_layout_seq          *lls;
+       struct lfsck_layout_seq          *next;
+       struct lfsck_layout_slave_target *llst;
+       struct lfsck_layout_slave_target *tmp;
+
+       LASSERT(llsd != NULL);
+
+       list_for_each_entry_safe(lls, next, &llsd->llsd_seq_list,
+                                    lls_list) {
+               list_del_init(&lls->lls_list);
+               lfsck_object_put(env, lls->lls_lastid_obj);
+               OBD_FREE_PTR(lls);
+       }
+
+       list_for_each_entry_safe(llst, tmp, &llsd->llsd_master_list,
+                                llst_list) {
+               list_del_init(&llst->llst_list);
+               OBD_FREE_PTR(llst);
+       }
+
+       lfsck_rbtree_cleanup(env, com);
+       com->lc_data = NULL;
+       OBD_FREE_PTR(llsd);
+}
+
+static void lfsck_layout_master_quit(const struct lu_env *env,
+                                    struct lfsck_component *com)
+{
+       struct lfsck_layout_master_data *llmd    = com->lc_data;
+       struct ptlrpc_thread            *mthread = &com->lc_lfsck->li_thread;
+       struct ptlrpc_thread            *athread = &llmd->llmd_thread;
+       struct l_wait_info               lwi     = { 0 };
+
+       llmd->llmd_exit = 1;
+       wake_up_all(&athread->t_ctl_waitq);
+       l_wait_event(mthread->t_ctl_waitq,
+                    thread_is_init(athread) ||
+                    thread_is_stopped(athread),
+                    &lwi);
+}
+
+static void lfsck_layout_slave_quit(const struct lu_env *env,
+                                   struct lfsck_component *com)
+{
+       lfsck_rbtree_cleanup(env, com);
+}
+
+static int lfsck_layout_master_in_notify(const struct lu_env *env,
+                                        struct lfsck_component *com,
+                                        struct lfsck_request *lr)
+{
+       struct lfsck_instance           *lfsck = com->lc_lfsck;
+       struct lfsck_layout             *lo    = com->lc_file_ram;
+       struct lfsck_layout_master_data *llmd  = com->lc_data;
+       struct lfsck_tgt_descs          *ltds;
+       struct lfsck_tgt_desc           *ltd;
+       ENTRY;
+
+       if (lr->lr_event != LE_PHASE1_DONE &&
+           lr->lr_event != LE_PHASE2_DONE &&
+           lr->lr_event != LE_STOP)
+               RETURN(-EINVAL);
+
+       if (lr->lr_flags & LEF_FROM_OST)
+               ltds = &lfsck->li_ost_descs;
+       else
+               ltds = &lfsck->li_mdt_descs;
+       spin_lock(&ltds->ltd_lock);
+       ltd = LTD_TGT(ltds, lr->lr_index);
+       if (ltd == NULL) {
+               spin_unlock(&ltds->ltd_lock);
+
+               RETURN(-ENODEV);
+       }
+
+       list_del_init(&ltd->ltd_layout_phase_list);
+       switch (lr->lr_event) {
+       case LE_PHASE1_DONE:
+               if (lr->lr_status <= 0) {
+                       ltd->ltd_layout_done = 1;
+                       list_del_init(&ltd->ltd_layout_list);
+                       lo->ll_flags |= LF_INCOMPLETE;
+                       break;
+               }
+
+               if (lr->lr_flags & LEF_FROM_OST) {
+                       if (list_empty(&ltd->ltd_layout_list))
+                               list_add_tail(&ltd->ltd_layout_list,
+                                             &llmd->llmd_ost_list);
+                       list_add_tail(&ltd->ltd_layout_phase_list,
+                                     &llmd->llmd_ost_phase2_list);
+               } else {
+                       if (list_empty(&ltd->ltd_layout_list))
+                               list_add_tail(&ltd->ltd_layout_list,
+                                             &llmd->llmd_mdt_list);
+                       list_add_tail(&ltd->ltd_layout_phase_list,
+                                     &llmd->llmd_mdt_phase2_list);
+               }
+               break;
+       case LE_PHASE2_DONE:
+               ltd->ltd_layout_done = 1;
+               list_del_init(&ltd->ltd_layout_list);
+               break;
+       case LE_STOP:
+               ltd->ltd_layout_done = 1;
+               list_del_init(&ltd->ltd_layout_list);
+               if (!(lr->lr_flags & LEF_FORCE_STOP))
+                       lo->ll_flags |= LF_INCOMPLETE;
+               break;
+       default:
+               break;
+       }
+       spin_unlock(&ltds->ltd_lock);
+
+       if (lr->lr_flags & LEF_FORCE_STOP) {
+               struct lfsck_stop *stop = &lfsck_env_info(env)->lti_stop;
+
+               memset(stop, 0, sizeof(*stop));
+               stop->ls_status = lr->lr_status;
+               stop->ls_flags = lr->lr_param;
+               lfsck_stop(env, lfsck->li_bottom, stop);
+       } else if (lfsck_layout_master_to_orphan(llmd)) {
+               wake_up_all(&llmd->llmd_thread.t_ctl_waitq);
+       }
+
+       RETURN(0);
+}
+
+static int lfsck_layout_slave_in_notify(const struct lu_env *env,
+                                       struct lfsck_component *com,
+                                       struct lfsck_request *lr)
+{
+       struct lfsck_instance            *lfsck = com->lc_lfsck;
+       struct lfsck_layout_slave_data   *llsd  = com->lc_data;
+       struct lfsck_layout_slave_target *llst;
+       ENTRY;
+
+       if (lr->lr_event == LE_FID_ACCESSED) {
+               lfsck_rbtree_update_bitmap(env, com, &lr->lr_fid, true);
+
+               RETURN(0);
+       }
+
+       if (lr->lr_event != LE_PHASE2_DONE &&
+           lr->lr_event != LE_STOP)
+               RETURN(-EINVAL);
+
+       llst = lfsck_layout_llst_find_and_del(llsd, lr->lr_index);
+       if (llst == NULL)
+               RETURN(-ENODEV);
+
+       lfsck_layout_llst_put(llst);
+       if (list_empty(&llsd->llsd_master_list)) {
+               switch (lr->lr_event) {
+               case LE_PHASE2_DONE:
+                       wake_up_all(&lfsck->li_thread.t_ctl_waitq);
+                       break;
+               case LE_STOP: {
+                       struct lfsck_stop *stop = &lfsck_env_info(env)->lti_stop;
+
+                       memset(stop, 0, sizeof(*stop));
+                       stop->ls_status = lr->lr_status;
+                       stop->ls_flags = lr->lr_param;
+                       lfsck_stop(env, lfsck->li_bottom, stop);
+                       break;
+               }
+               default:
+                       break;
+               }
+       }
+
+       RETURN(0);
+}
+
+static int lfsck_layout_query(const struct lu_env *env,
+                             struct lfsck_component *com)
+{
+       struct lfsck_layout *lo = com->lc_file_ram;
+
+       return lo->ll_status;
+}
+
+static int lfsck_layout_master_stop_notify(const struct lu_env *env,
+                                          struct lfsck_component *com,
+                                          struct lfsck_tgt_descs *ltds,
+                                          struct lfsck_tgt_desc *ltd,
+                                          struct ptlrpc_request_set *set)
+{
+       struct lfsck_thread_info          *info  = lfsck_env_info(env);
+       struct lfsck_async_interpret_args *laia  = &info->lti_laia;
+       struct lfsck_request              *lr    = &info->lti_lr;
+       struct lfsck_instance             *lfsck = com->lc_lfsck;
+       int                                rc;
+
+       LASSERT(list_empty(&ltd->ltd_layout_list));
+       LASSERT(list_empty(&ltd->ltd_layout_phase_list));
+
+       memset(lr, 0, sizeof(*lr));
+       lr->lr_index = lfsck_dev_idx(lfsck->li_bottom);
+       lr->lr_event = LE_STOP;
+       lr->lr_active = LT_LAYOUT;
+       if (ltds == &lfsck->li_ost_descs) {
+               lr->lr_flags = LEF_TO_OST;
+       } else {
+               if (ltd->ltd_index == lfsck_dev_idx(lfsck->li_bottom))
+                       return 0;
+
+               lr->lr_flags = 0;
+       }
+       lr->lr_status = LS_CO_STOPPED;
+
+       laia->laia_com = com;
+       laia->laia_ltds = ltds;
+       laia->laia_ltd = ltd;
+       laia->laia_lr = lr;
+
+       rc = lfsck_async_request(env, ltd->ltd_exp, lr, set,
+                                lfsck_layout_master_async_interpret,
+                                laia, LFSCK_NOTIFY);
+       if (rc != 0)
+               CERROR("%s: 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);
+
+       return rc;
+}
+
+/* with lfsck::li_lock held */
+static int lfsck_layout_slave_join(const struct lu_env *env,
+                                  struct lfsck_component *com,
+                                  struct lfsck_start_param *lsp)
+{
+       struct lfsck_instance            *lfsck = com->lc_lfsck;
+       struct lfsck_layout_slave_data   *llsd  = com->lc_data;
+       struct lfsck_layout_slave_target *llst;
+       struct lfsck_start               *start = lsp->lsp_start;
+       int                               rc    = 0;
+       ENTRY;
+
+       if (!lsp->lsp_index_valid || start == NULL ||
+           !(start->ls_flags & LPF_ALL_MDT))
+               RETURN(-EALREADY);
+
+       spin_unlock(&lfsck->li_lock);
+       rc = lfsck_layout_llst_add(llsd, lsp->lsp_index);
+       spin_lock(&lfsck->li_lock);
+       if (rc == 0 && !thread_is_running(&lfsck->li_thread)) {
+               spin_unlock(&lfsck->li_lock);
+               llst = lfsck_layout_llst_find_and_del(llsd, lsp->lsp_index);
+               if (llst != NULL)
+                       lfsck_layout_llst_put(llst);
+               spin_lock(&lfsck->li_lock);
+               rc = -EAGAIN;
+       }
+
+       RETURN(rc);
 }
 
 static struct lfsck_operations lfsck_layout_master_ops = {
        .lfsck_reset            = lfsck_layout_reset,
        .lfsck_fail             = lfsck_layout_fail,
-       .lfsck_checkpoint       = lfsck_layout_checkpoint,
+       .lfsck_checkpoint       = lfsck_layout_master_checkpoint,
        .lfsck_prep             = lfsck_layout_master_prep,
        .lfsck_exec_oit         = lfsck_layout_master_exec_oit,
        .lfsck_exec_dir         = lfsck_layout_exec_dir,
        .lfsck_post             = lfsck_layout_master_post,
        .lfsck_dump             = lfsck_layout_dump,
        .lfsck_double_scan      = lfsck_layout_master_double_scan,
+       .lfsck_data_release     = lfsck_layout_master_data_release,
+       .lfsck_quit             = lfsck_layout_master_quit,
+       .lfsck_in_notify        = lfsck_layout_master_in_notify,
+       .lfsck_query            = lfsck_layout_query,
+       .lfsck_stop_notify      = lfsck_layout_master_stop_notify,
 };
 
 static struct lfsck_operations lfsck_layout_slave_ops = {
        .lfsck_reset            = lfsck_layout_reset,
        .lfsck_fail             = lfsck_layout_fail,
-       .lfsck_checkpoint       = lfsck_layout_checkpoint,
+       .lfsck_checkpoint       = lfsck_layout_slave_checkpoint,
        .lfsck_prep             = lfsck_layout_slave_prep,
        .lfsck_exec_oit         = lfsck_layout_slave_exec_oit,
        .lfsck_exec_dir         = lfsck_layout_exec_dir,
        .lfsck_post             = lfsck_layout_slave_post,
        .lfsck_dump             = lfsck_layout_dump,
        .lfsck_double_scan      = lfsck_layout_slave_double_scan,
+       .lfsck_data_release     = lfsck_layout_slave_data_release,
+       .lfsck_quit             = lfsck_layout_slave_quit,
+       .lfsck_in_notify        = lfsck_layout_slave_in_notify,
+       .lfsck_query            = lfsck_layout_query,
+       .lfsck_join             = lfsck_layout_slave_join,
 };
 
 int lfsck_layout_setup(const struct lu_env *env, struct lfsck_instance *lfsck)
@@ -363,10 +4169,39 @@ int lfsck_layout_setup(const struct lu_env *env, struct lfsck_instance *lfsck)
        atomic_set(&com->lc_ref, 1);
        com->lc_lfsck = lfsck;
        com->lc_type = LT_LAYOUT;
-       if (lfsck->li_master)
+       if (lfsck->li_master) {
+               struct lfsck_layout_master_data *llmd;
+
                com->lc_ops = &lfsck_layout_master_ops;
-       else
+               OBD_ALLOC_PTR(llmd);
+               if (llmd == NULL)
+                       GOTO(out, rc = -ENOMEM);
+
+               INIT_LIST_HEAD(&llmd->llmd_req_list);
+               spin_lock_init(&llmd->llmd_lock);
+               INIT_LIST_HEAD(&llmd->llmd_ost_list);
+               INIT_LIST_HEAD(&llmd->llmd_ost_phase1_list);
+               INIT_LIST_HEAD(&llmd->llmd_ost_phase2_list);
+               INIT_LIST_HEAD(&llmd->llmd_mdt_list);
+               INIT_LIST_HEAD(&llmd->llmd_mdt_phase1_list);
+               INIT_LIST_HEAD(&llmd->llmd_mdt_phase2_list);
+               init_waitqueue_head(&llmd->llmd_thread.t_ctl_waitq);
+               com->lc_data = llmd;
+       } else {
+               struct lfsck_layout_slave_data *llsd;
+
                com->lc_ops = &lfsck_layout_slave_ops;
+               OBD_ALLOC_PTR(llsd);
+               if (llsd == NULL)
+                       GOTO(out, rc = -ENOMEM);
+
+               INIT_LIST_HEAD(&llsd->llsd_seq_list);
+               INIT_LIST_HEAD(&llsd->llsd_master_list);
+               spin_lock_init(&llsd->llsd_lock);
+               llsd->llsd_rb_root = RB_ROOT;
+               rwlock_init(&llsd->llsd_rb_lock);
+               com->lc_data = llsd;
+       }
        com->lc_file_size = sizeof(*lo);
        OBD_ALLOC(com->lc_file_ram, com->lc_file_size);
        if (com->lc_file_ram == NULL)
@@ -424,12 +4259,22 @@ int lfsck_layout_setup(const struct lu_env *env, struct lfsck_instance *lfsck)
                /* fall through */
        case LS_PAUSED:
        case LS_CRASHED:
+       case LS_CO_FAILED:
+       case LS_CO_STOPPED:
+       case LS_CO_PAUSED:
                spin_lock(&lfsck->li_lock);
                list_add_tail(&com->lc_link, &lfsck->li_list_scan);
                spin_unlock(&lfsck->li_lock);
                break;
        }
 
+       if (lo->ll_flags & LF_CRASHED_LASTID) {
+               LASSERT(lfsck->li_out_notify != NULL);
+
+               lfsck->li_out_notify(env, lfsck->li_out_notify_data,
+                                    LE_LASTID_REBUILDING);
+       }
+
        GOTO(out, rc = 0);
 
 out: