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LU-12635 build: Support for gcc -Wimplicit-fallthrough
[fs/lustre-release.git] / lustre / lod / lod_object.c
index 50b40b8..1fa0ffb 100644 (file)
@@ -1419,7 +1419,7 @@ static int lod_attr_set(const struct lu_env *env,
                buf->lb_len = info->lti_ea_store_size;
                lmm = info->lti_ea_store;
                magic = le32_to_cpu(lmm->lmm_magic);
-               if (magic == LOV_MAGIC_COMP_V1) {
+               if (magic == LOV_MAGIC_COMP_V1 || magic == LOV_MAGIC_SEL) {
                        struct lov_comp_md_v1 *lcm = buf->lb_buf;
                        struct lov_comp_md_entry_v1 *lcme =
                                                &lcm->lcm_entries[0];
@@ -1453,7 +1453,8 @@ static int lod_attr_set(const struct lu_env *env,
                buf->lb_buf = info->lti_ea_store;
                buf->lb_len = info->lti_ea_store_size;
                lcm = buf->lb_buf;
-               if (le32_to_cpu(lcm->lcm_magic) != LOV_MAGIC_COMP_V1)
+               if (le32_to_cpu(lcm->lcm_magic) != LOV_MAGIC_COMP_V1 &&
+                   le32_to_cpu(lcm->lcm_magic) != LOV_MAGIC_SEL)
                        RETURN(-EINVAL);
 
                le32_add_cpu(&lcm->lcm_layout_gen, 1);
@@ -1543,6 +1544,13 @@ static int lod_xattr_get(const struct lu_env *env, struct dt_object *dt,
                RETURN(rc = rc1 != 0 ? rc1 : rc);
        }
 
+       if ((rc > 0) && buf->lb_buf && strcmp(name, XATTR_NAME_LOV) == 0) {
+               struct lov_comp_md_v1 *lcm = buf->lb_buf;
+
+               if (lcm->lcm_magic == cpu_to_le32(LOV_MAGIC_SEL))
+                       lcm->lcm_magic = cpu_to_le32(LOV_MAGIC_COMP_V1);
+       }
+
        if (rc != -ENODATA || !S_ISDIR(dt->do_lu.lo_header->loh_attr & S_IFMT))
                RETURN(rc);
 
@@ -3264,6 +3272,7 @@ static int lod_declare_layout_merge(const struct lu_env *env,
                rc = lod_layout_convert(info);
                break;
        case LOV_MAGIC_COMP_V1:
+       case LOV_MAGIC_SEL:
                rc = 0;
                break;
        default:
@@ -3630,8 +3639,23 @@ static int lod_xattr_set_lov_on_dir(const struct lu_env *env,
                                             pool_name);
                break;
        case LOV_USER_MAGIC_COMP_V1:
+       {
+               struct lov_comp_md_v1 *lcm = (struct lov_comp_md_v1 *)lum;
+               struct lov_comp_md_entry_v1 *lcme;
+               int i, comp_cnt;
+
+               comp_cnt = le16_to_cpu(lcm->lcm_entry_count);
+               for (i = 0; i < comp_cnt; i++) {
+                       lcme = &lcm->lcm_entries[i];
+                       if (lcme->lcme_flags & cpu_to_le32(LCME_FL_EXTENSION)) {
+                               lcm->lcm_magic = cpu_to_le32(LOV_MAGIC_SEL);
+                               break;
+                       }
+               }
+
                is_del = false;
                break;
+       }
        default:
                CERROR("Invalid magic %x\n", lum->lmm_magic);
                RETURN(-EINVAL);
@@ -3689,7 +3713,7 @@ static int lod_xattr_set_default_lmv_on_dir(const struct lu_env *env,
        if (LMVEA_DELETE_VALUES((le32_to_cpu(lum->lum_stripe_count)),
                                 le32_to_cpu(lum->lum_stripe_offset)) &&
            le32_to_cpu(lum->lum_magic) == LMV_USER_MAGIC &&
-           le32_to_cpu(lum->lum_hash_type) != LMV_HASH_TYPE_SPACE) {
+           !(le32_to_cpu(lum->lum_hash_type) & LMV_HASH_FLAG_SPACE)) {
                rc = lod_xattr_del_internal(env, dt, name, th);
                if (rc == -ENODATA)
                        rc = 0;
@@ -3793,7 +3817,7 @@ static int lod_xattr_set_lmv(const struct lu_env *env, struct dt_object *dt,
                /* if it's source stripe of migrating directory, don't create */
                if (!((lo->ldo_dir_hash_type & LMV_HASH_FLAG_MIGRATION) &&
                      i >= lo->ldo_dir_migrate_offset)) {
-                       dt_write_lock(env, dto, MOR_TGT_CHILD);
+                       dt_write_lock(env, dto, DT_TGT_CHILD);
                        rc = lod_sub_create(env, dto, attr, NULL, dof, th);
                        if (rc != 0) {
                                dt_write_unlock(env, dto);
@@ -4119,37 +4143,195 @@ static int lod_generate_and_set_lovea(const struct lu_env *env,
        RETURN(rc);
 }
 
+static __u32 lod_gen_component_id(struct lod_object *lo,
+                                 int mirror_id, int comp_idx);
+
 /**
- * Delete layout component(s)
+ * Repeat an existing component
+ *
+ * Creates a new layout by replicating an existing component.  Uses striping
+ * policy from previous component as a template for the striping for the new
+ * new component.
+ *
+ * New component starts with zero length, will be extended (or removed) before
+ * returning layout to client.
+ *
+ * NB: Reallocates layout components array (lo->ldo_comp_entries), invalidating
+ * any pre-existing pointers to components.  Handle with care.
  *
  * \param[in] env      execution environment for this thread
- * \param[in] dt       object
- * \param[in] th       transaction handle
+ * \param[in,out] lo   object to update the layout of
+ * \param[in] index    index of component to copy
  *
  * \retval     0 on success
- * \retval     negative error number on failure
+ * \retval     negative errno on error
  */
-static int lod_layout_del(const struct lu_env *env, struct dt_object *dt,
-                         struct thandle *th)
+static int lod_layout_repeat_comp(const struct lu_env *env,
+                                 struct lod_object *lo, int index)
 {
-       struct lod_layout_component     *lod_comp;
-       struct lod_object       *lo = lod_dt_obj(dt);
-       struct dt_object        *next = dt_object_child(dt);
-       struct lu_attr  *attr = &lod_env_info(env)->lti_attr;
-       int     rc, i, j, left;
+       struct lod_layout_component *lod_comp;
+       struct lod_layout_component *new_comp = NULL;
+       struct lod_layout_component *comp_array;
+       int rc = 0, i, new_cnt = lo->ldo_comp_cnt + 1;
+       __u16 mirror_id;
+       int offset = 0;
+       ENTRY;
+
+       lod_comp = &lo->ldo_comp_entries[index];
+       LASSERT(lod_comp_inited(lod_comp) && lod_comp->llc_id != LCME_ID_INVAL);
+
+       CDEBUG(D_LAYOUT, "repeating component %d\n", index);
+
+       OBD_ALLOC(comp_array, sizeof(*comp_array) * new_cnt);
+       if (comp_array == NULL)
+               GOTO(out, rc = -ENOMEM);
+
+       for (i = 0; i < lo->ldo_comp_cnt; i++) {
+               memcpy(&comp_array[i + offset], &lo->ldo_comp_entries[i],
+                      sizeof(*comp_array));
+
+               /* Duplicate this component in to the next slot */
+               if (i == index) {
+                       new_comp = &comp_array[i + 1];
+                       memcpy(&comp_array[i + 1], &lo->ldo_comp_entries[i],
+                              sizeof(*comp_array));
+                       /* We must now skip this new component when copying */
+                       offset = 1;
+               }
+       }
+
+       /* Set up copied component */
+       new_comp->llc_flags &= ~LCME_FL_INIT;
+       new_comp->llc_stripe = NULL;
+       new_comp->llc_stripes_allocated = 0;
+       new_comp->llc_stripe_offset = LOV_OFFSET_DEFAULT;
+       /* for uninstantiated components, layout gen stores default stripe
+        * offset */
+       new_comp->llc_layout_gen = lod_comp->llc_stripe_offset;
+       /* This makes the repeated component zero-length, placed at the end of
+        * the preceding component */
+       new_comp->llc_extent.e_start = new_comp->llc_extent.e_end;
+       new_comp->llc_timestamp = lod_comp->llc_timestamp;
+       new_comp->llc_pool = NULL;
+
+       rc = lod_set_pool(&new_comp->llc_pool, lod_comp->llc_pool);
+       if (rc)
+               GOTO(out, rc);
+
+       if (new_comp->llc_ostlist.op_array) {
+               __u32 *op_array = NULL;
+
+               OBD_ALLOC(op_array, new_comp->llc_ostlist.op_size);
+               if (!op_array)
+                       GOTO(out, rc = -ENOMEM);
+               memcpy(op_array, &new_comp->llc_ostlist.op_array,
+                      new_comp->llc_ostlist.op_size);
+               new_comp->llc_ostlist.op_array = op_array;
+       }
+
+       OBD_FREE(lo->ldo_comp_entries,
+                sizeof(*comp_array) * lo->ldo_comp_cnt);
+       lo->ldo_comp_entries = comp_array;
+       lo->ldo_comp_cnt = new_cnt;
+
+       /* Generate an id for the new component */
+       mirror_id = mirror_id_of(new_comp->llc_id);
+       new_comp->llc_id = LCME_ID_INVAL;
+       new_comp->llc_id = lod_gen_component_id(lo, mirror_id, index + 1);
+       if (new_comp->llc_id == LCME_ID_INVAL)
+               GOTO(out, rc = -ERANGE);
+
+       EXIT;
+out:
+       if (rc)
+               OBD_FREE(comp_array, sizeof(*comp_array) * new_cnt);
+
+       return rc;
+}
+
+static int lod_layout_data_init(struct lod_thread_info *info, __u32 comp_cnt)
+{
+       ENTRY;
+
+       /* clear memory region that will be used for layout change */
+       memset(&info->lti_layout_attr, 0, sizeof(struct lu_attr));
+       info->lti_count = 0;
+
+       if (info->lti_comp_size >= comp_cnt)
+               RETURN(0);
+
+       if (info->lti_comp_size > 0) {
+               OBD_FREE(info->lti_comp_idx,
+                        info->lti_comp_size * sizeof(__u32));
+               info->lti_comp_size = 0;
+       }
+
+       OBD_ALLOC(info->lti_comp_idx, comp_cnt * sizeof(__u32));
+       if (!info->lti_comp_idx)
+               RETURN(-ENOMEM);
+
+       info->lti_comp_size = comp_cnt;
+       RETURN(0);
+}
+
+/**
+ * Prepare new layout minus deleted components
+ *
+ * Removes components marked for deletion (LCME_ID_INVAL) by copying to a new
+ * layout and skipping those components.  Removes stripe objects if any exist.
+ *
+ * NB:
+ * Reallocates layout components array (lo->ldo_comp_entries), invalidating
+ * any pre-existing pointers to components.
+ *
+ * Caller is responsible for updating mirror end (ldo_mirror[].lme_end).
+ *
+ * \param[in] env       execution environment for this thread
+ * \param[in,out] lo    object to update the layout of
+ * \param[in] th        transaction handle for this operation
+ *
+ * \retval      # of components deleted
+ * \retval      negative errno on error
+ */
+static int lod_layout_del_prep_layout(const struct lu_env *env,
+                                     struct lod_object *lo,
+                                     struct thandle *th)
+{
+       struct lod_layout_component     *lod_comp;
+       struct lod_thread_info  *info = lod_env_info(env);
+       int rc = 0, i, j, deleted = 0;
+
+       ENTRY;
 
        LASSERT(lo->ldo_is_composite);
        LASSERT(lo->ldo_comp_cnt > 0 && lo->ldo_comp_entries != NULL);
 
-       left = lo->ldo_comp_cnt;
-       for (i = (lo->ldo_comp_cnt - 1); i >= 0; i--) {
+       rc = lod_layout_data_init(info, lo->ldo_comp_cnt);
+       if (rc)
+               RETURN(rc);
+
+       for (i = 0; i < lo->ldo_comp_cnt; i++) {
                lod_comp = &lo->ldo_comp_entries[i];
 
-               if (lod_comp->llc_id != LCME_ID_INVAL)
-                       break;
-               left--;
+               if (lod_comp->llc_id != LCME_ID_INVAL) {
+                       /* Build array of things to keep */
+                       info->lti_comp_idx[info->lti_count++] = i;
+                       continue;
+               }
 
-               /* Not instantiated component */
+               lod_obj_set_pool(lo, i, NULL);
+               if (lod_comp->llc_ostlist.op_array) {
+                       OBD_FREE(lod_comp->llc_ostlist.op_array,
+                                lod_comp->llc_ostlist.op_size);
+                       lod_comp->llc_ostlist.op_array = NULL;
+                       lod_comp->llc_ostlist.op_size = 0;
+               }
+
+               deleted++;
+               CDEBUG(D_LAYOUT, "deleting comp %d, left %d\n", i,
+                      lo->ldo_comp_cnt - deleted);
+
+               /* No striping info for this component */
                if (lod_comp->llc_stripe == NULL)
                        continue;
 
@@ -4159,9 +4341,14 @@ static int lod_layout_del(const struct lu_env *env, struct dt_object *dt,
 
                        if (obj == NULL)
                                continue;
-                       rc = lod_sub_destroy(env, obj, th);
-                       if (rc)
-                               GOTO(out, rc);
+
+                       /* components which are not init have no sub objects
+                        * to destroy */
+                       if (lod_comp_inited(lod_comp)) {
+                               rc = lod_sub_destroy(env, obj, th);
+                               if (rc)
+                                       GOTO(out, rc);
+                       }
 
                        lu_object_put(env, &obj->do_lu);
                        lod_comp->llc_stripe[j] = NULL;
@@ -4173,38 +4360,73 @@ static int lod_layout_del(const struct lu_env *env, struct dt_object *dt,
                         sizeof(__u32) * lod_comp->llc_stripes_allocated);
                lod_comp->llc_ost_indices = NULL;
                lod_comp->llc_stripes_allocated = 0;
-               lod_obj_set_pool(lo, i, NULL);
-               if (lod_comp->llc_ostlist.op_array) {
-                       OBD_FREE(lod_comp->llc_ostlist.op_array,
-                                lod_comp->llc_ostlist.op_size);
-                       lod_comp->llc_ostlist.op_array = NULL;
-                       lod_comp->llc_ostlist.op_size = 0;
-               }
        }
 
-       LASSERTF(left >= 0 && left < lo->ldo_comp_cnt, "left = %d\n", left);
-       if (left > 0) {
-               struct lod_layout_component     *comp_array;
+       /* info->lti_count has the amount of left components */
+       LASSERTF(info->lti_count >= 0 && info->lti_count < lo->ldo_comp_cnt,
+                "left = %d, lo->ldo_comp_cnt %d\n", (int)info->lti_count,
+                (int)lo->ldo_comp_cnt);
+
+       if (info->lti_count > 0) {
+               struct lod_layout_component *comp_array;
 
-               OBD_ALLOC(comp_array, sizeof(*comp_array) * left);
+               OBD_ALLOC(comp_array, sizeof(*comp_array) * info->lti_count);
                if (comp_array == NULL)
                        GOTO(out, rc = -ENOMEM);
 
-               memcpy(&comp_array[0], &lo->ldo_comp_entries[0],
-                      sizeof(*comp_array) * left);
+               for (i = 0; i < info->lti_count; i++) {
+                       memcpy(&comp_array[i],
+                              &lo->ldo_comp_entries[info->lti_comp_idx[i]],
+                              sizeof(*comp_array));
+               }
 
                OBD_FREE(lo->ldo_comp_entries,
                         sizeof(*comp_array) * lo->ldo_comp_cnt);
                lo->ldo_comp_entries = comp_array;
-               lo->ldo_comp_cnt = left;
-
-               LASSERT(lo->ldo_mirror_count == 1);
-               lo->ldo_mirrors[0].lme_end = left - 1;
-               lod_obj_inc_layout_gen(lo);
+               lo->ldo_comp_cnt = info->lti_count;
        } else {
                lod_free_comp_entries(lo);
        }
 
+       EXIT;
+out:
+       return rc ? rc : deleted;
+}
+
+/**
+ * Delete layout component(s)
+ *
+ * This function sets up the layout data in the env and does the setattrs
+ * required to write out the new layout.  The layout itself is modified in
+ * lod_layout_del_prep_layout.
+ *
+ * \param[in] env      execution environment for this thread
+ * \param[in] dt       object
+ * \param[in] th       transaction handle
+ *
+ * \retval     0 on success
+ * \retval     negative error number on failure
+ */
+static int lod_layout_del(const struct lu_env *env, struct dt_object *dt,
+                         struct thandle *th)
+{
+       struct lod_object *lo = lod_dt_obj(dt);
+       struct dt_object *next = dt_object_child(dt);
+       struct lu_attr *attr = &lod_env_info(env)->lti_attr;
+       int rc;
+
+       LASSERT(lo->ldo_mirror_count == 1);
+
+       rc = lod_layout_del_prep_layout(env, lo, th);
+       if (rc < 0)
+               GOTO(out, rc);
+
+       /* Only do this if we didn't delete all components */
+       if (lo->ldo_comp_cnt > 0) {
+               lo->ldo_mirrors[0].lme_end = lo->ldo_comp_cnt - 1;
+               lod_obj_inc_layout_gen(lo);
+       }
+
        LASSERT(dt_object_exists(dt));
        rc = dt_attr_get(env, next, attr);
        if (rc)
@@ -4416,7 +4638,13 @@ static int lod_declare_xattr_del(const struct lu_env *env,
        if (!S_ISDIR(dt->do_lu.lo_header->loh_attr))
                RETURN(0);
 
-       /* set xattr to each stripes, if needed */
+       /* NB: don't delete stripe LMV, because when we do this, normally we
+        * will remove stripes, besides, if directory LMV is corrupt, this will
+        * prevent deleting its LMV and fixing it (via LFSCK).
+        */
+       if (!strcmp(name, XATTR_NAME_LMV))
+               RETURN(0);
+
        rc = lod_striping_load(env, lo);
        if (rc != 0)
                RETURN(rc);
@@ -4462,6 +4690,9 @@ static int lod_xattr_del(const struct lu_env *env, struct dt_object *dt,
        if (rc != 0 || !S_ISDIR(dt->do_lu.lo_header->loh_attr))
                RETURN(rc);
 
+       if (!strcmp(name, XATTR_NAME_LMV))
+               RETURN(0);
+
        if (lo->ldo_dir_stripe_count == 0)
                RETURN(0);
 
@@ -4586,17 +4817,20 @@ static int lod_get_default_lov_striping(const struct lu_env *env,
                lustre_swab_lov_user_md_v3(v3);
                lustre_swab_lov_user_md_objects(v3->lmm_objects,
                                                v3->lmm_stripe_count);
-       } else if (v1->lmm_magic == __swab32(LOV_USER_MAGIC_COMP_V1)) {
+       } else if (v1->lmm_magic == __swab32(LOV_USER_MAGIC_COMP_V1) ||
+                  v1->lmm_magic == __swab32(LOV_USER_MAGIC_SEL)) {
                comp_v1 = (struct lov_comp_md_v1 *)v1;
                lustre_swab_lov_comp_md_v1(comp_v1);
        }
 
        if (v1->lmm_magic != LOV_MAGIC_V3 && v1->lmm_magic != LOV_MAGIC_V1 &&
            v1->lmm_magic != LOV_MAGIC_COMP_V1 &&
+           v1->lmm_magic != LOV_MAGIC_SEL &&
            v1->lmm_magic != LOV_USER_MAGIC_SPECIFIC)
                RETURN(-ENOTSUPP);
 
-       if (v1->lmm_magic == LOV_MAGIC_COMP_V1) {
+       if (v1->lmm_magic == LOV_MAGIC_COMP_V1 ||
+           v1->lmm_magic == LOV_MAGIC_SEL) {
                comp_v1 = (struct lov_comp_md_v1 *)v1;
                comp_cnt = comp_v1->lcm_entry_count;
                if (comp_cnt == 0)
@@ -4834,14 +5068,8 @@ static void lod_striping_from_default(struct lod_object *lo,
                        lo->ldo_dir_stripe_offset =
                                lds->lds_dir_def_stripe_offset;
                if (lo->ldo_dir_hash_type == 0)
-                       lo->ldo_dir_hash_type = lds->lds_dir_def_hash_type;
-
-               /*
-                * "space" hash type can only be set in default LMV, child use
-                * FNV_1A_64 in case it's striped.
-                */
-               if (lo->ldo_dir_hash_type == LMV_HASH_TYPE_SPACE)
-                       lo->ldo_dir_hash_type = LMV_HASH_TYPE_FNV_1A_64;
+                       lo->ldo_dir_hash_type = lds->lds_dir_def_hash_type &
+                                               ~LMV_HASH_FLAG_SPACE;
 
                CDEBUG(D_LAYOUT, "striping from default dir: count:%hu, "
                       "offset:%u, hash_type:%u\n",
@@ -5243,14 +5471,29 @@ out:
        RETURN(rc);
 }
 
-static inline int dt_object_space_hashed(const struct lu_env *env,
-                                        struct lu_device *dev,
-                                        struct dt_object *dt)
+/*
+ * Whether subdirectories under \a dt should be created on MDTs by space QoS
+ *
+ * If LMV_HASH_FLAG_SPACE is set on directory default layout, its subdirectories
+ * should be created on MDT by space QoS.
+ *
+ * \param[in] env      execution environment
+ * \param[in] dev      lu device
+ * \param[in] dt       object
+ *
+ * \retval             1 if directory should create subdir by space usage
+ * \retval             0 if not
+ * \retval             -ev if failed
+ */
+static inline int dt_object_qos_mkdir(const struct lu_env *env,
+                                     struct lu_device *dev,
+                                     struct dt_object *dt)
 {
+       struct lod_thread_info *info = lod_env_info(env);
        struct lu_object *obj;
        struct lod_object *lo;
        struct lmv_user_md *lmu;
-       int rc = 0;
+       int rc;
 
        obj = lu_object_find_slice(env, dev, lu_object_fid(&dt->do_lu), NULL);
        if (IS_ERR(obj))
@@ -5259,18 +5502,15 @@ static inline int dt_object_space_hashed(const struct lu_env *env,
        lo = lu2lod_obj(obj);
 
        rc = lod_get_default_lmv_ea(env, lo);
-       if (rc < 0)
+       dt_object_put(env, dt);
+       if (rc <= 0)
                return rc;
 
-       if (rc >= (int)sizeof(*lmu)) {
-               struct lod_thread_info *info = lod_env_info(env);
-
-               lmu = info->lti_ea_store;
-               rc = le32_to_cpu(lmu->lum_hash_type) == LMV_HASH_TYPE_SPACE;
-       }
-       dt_object_put(env, dt);
+       if (rc < (int)sizeof(*lmu))
+               return -EINVAL;
 
-       return rc;
+       lmu = info->lti_ea_store;
+       return !!(le32_to_cpu(lmu->lum_hash_type) & LMV_HASH_FLAG_SPACE);
 }
 
 /**
@@ -5343,7 +5583,7 @@ static int lod_declare_create(const struct lu_env *env, struct dt_object *dt,
                                 */
                                if (hint->dah_parent &&
                                    dt_object_remote(hint->dah_parent)) {
-                                       rc = dt_object_space_hashed(env,
+                                       rc = dt_object_qos_mkdir(env,
                                                       lo->ldo_obj.do_lu.lo_dev,
                                                       hint->dah_parent);
                                        if (rc <= 0)
@@ -5779,7 +6019,7 @@ static int lod_destroy(const struct lu_env *env, struct dt_object *dt,
 
                        if (!OBD_FAIL_CHECK(OBD_FAIL_LFSCK_LOST_SPEOBJ) ||
                            i == cfs_fail_val) {
-                               dt_write_lock(env, stripe, MOR_TGT_CHILD);
+                               dt_write_lock(env, stripe, DT_TGT_CHILD);
                                rc = lod_sub_ref_del(env, stripe, th);
                                dt_write_unlock(env, stripe);
                                if (rc != 0)
@@ -6013,31 +6253,6 @@ static int lod_invalidate(const struct lu_env *env, struct dt_object *dt)
        return dt_invalidate(env, dt_object_child(dt));
 }
 
-static int lod_layout_data_init(struct lod_thread_info *info, __u32 comp_cnt)
-{
-       ENTRY;
-
-       /* clear memory region that will be used for layout change */
-       memset(&info->lti_layout_attr, 0, sizeof(struct lu_attr));
-       info->lti_count = 0;
-
-       if (info->lti_comp_size >= comp_cnt)
-               RETURN(0);
-
-       if (info->lti_comp_size > 0) {
-               OBD_FREE(info->lti_comp_idx,
-                        info->lti_comp_size * sizeof(__u32));
-               info->lti_comp_size = 0;
-       }
-
-       OBD_ALLOC(info->lti_comp_idx, comp_cnt * sizeof(__u32));
-       if (!info->lti_comp_idx)
-               RETURN(-ENOMEM);
-
-       info->lti_comp_size = comp_cnt;
-       RETURN(0);
-}
-
 static int lod_declare_instantiate_components(const struct lu_env *env,
                struct lod_object *lo, struct thandle *th)
 {
@@ -6064,6 +6279,553 @@ static int lod_declare_instantiate_components(const struct lu_env *env,
        RETURN(rc);
 }
 
+/**
+ * Check OSTs for an existing component for further extension
+ *
+ * Checks if OSTs are still healthy and not out of space.  Gets free space
+ * on OSTs (relative to allocation watermark rmb_low) and compares to
+ * the proposed new_end for this component.
+ *
+ * Decides whether or not to extend a component on its current OSTs.
+ *
+ * \param[in] env              execution environment for this thread
+ * \param[in] lo               object we're checking
+ * \param[in] index            index of this component
+ * \param[in] extension_size   extension size for this component
+ * \param[in] extent           layout extent for requested operation
+ * \param[in] comp_extent      extension component extent
+ * \param[in] write            if this is write operation
+ *
+ * \retval     true - OK to extend on current OSTs
+ * \retval     false - do not extend on current OSTs
+ */
+static bool lod_sel_osts_allowed(const struct lu_env *env,
+                                struct lod_object *lo,
+                                int index, __u64 extension_size,
+                                struct lu_extent *extent,
+                                struct lu_extent *comp_extent, int write)
+{
+       struct lod_layout_component *lod_comp = &lo->ldo_comp_entries[index];
+       struct lod_device *lod = lu2lod_dev(lo->ldo_obj.do_lu.lo_dev);
+       struct obd_statfs *sfs = &lod_env_info(env)->lti_osfs;
+       __u64 available = 0;
+       __u64 size;
+       bool ret = true;
+       int i, rc;
+
+       ENTRY;
+
+       LASSERT(lod_comp->llc_stripe_count != 0);
+
+       if (write == 0 ||
+           (extent->e_start == 0 && extent->e_end == OBD_OBJECT_EOF)) {
+               /* truncate or append */
+               size = extension_size;
+       } else {
+               /* In case of write op, check the real write extent,
+                * it may be larger than the extension_size */
+               size = roundup(min(extent->e_end, comp_extent->e_end) -
+                              max(extent->e_start, comp_extent->e_start),
+                              extension_size);
+       }
+       /* extension_size is file level, so we must divide by stripe count to
+        * compare it to available space on a single OST */
+       size /= lod_comp->llc_stripe_count;
+
+       lod_getref(&lod->lod_ost_descs);
+       for (i = 0; i < lod_comp->llc_stripe_count; i++) {
+               int index = lod_comp->llc_ost_indices[i];
+               struct lod_tgt_desc *ost = OST_TGT(lod, index);
+               struct obd_statfs_info info = { 0 };
+               int j, repeated = 0;
+
+               LASSERT(ost);
+
+               /* Get the number of times this OST repeats in this component.
+                * Note: inter-component repeats are not counted as this is
+                * considered as a rare case: we try to not repeat OST in other
+                * components if possible. */
+               for (j = 0; j < lod_comp->llc_stripe_count; j++) {
+                       if (index != lod_comp->llc_ost_indices[j])
+                               continue;
+
+                       /* already handled */
+                       if (j < i)
+                               break;
+
+                       repeated++;
+               }
+               if (j < lod_comp->llc_stripe_count)
+                       continue;
+
+               if (!cfs_bitmap_check(lod->lod_ost_bitmap, index)) {
+                       CDEBUG(D_LAYOUT, "ost %d no longer present\n", index);
+                       ret = false;
+                       break;
+               }
+
+               rc = dt_statfs_info(env, ost->ltd_ost, sfs, &info);
+               if (rc) {
+                       CDEBUG(D_LAYOUT, "statfs failed for ost %d, error %d\n",
+                              index, rc);
+                       ret = false;
+                       break;
+               }
+
+               if (sfs->os_state & OS_STATE_ENOSPC ||
+                   sfs->os_state & OS_STATE_READONLY ||
+                   sfs->os_state & OS_STATE_DEGRADED) {
+                       CDEBUG(D_LAYOUT, "ost %d is not availble for SEL "
+                              "extension, state %u\n", index, sfs->os_state);
+                       ret = false;
+                       break;
+               }
+
+               /* In bytes */
+               available = sfs->os_bavail * sfs->os_bsize;
+               /* 'available' is relative to the allocation threshold */
+               available -= (__u64) info.os_reserved_mb_low << 20;
+
+               CDEBUG(D_LAYOUT, "ost %d lowwm: %d highwm: %d, "
+                      "%llu %% blocks available, %llu %% blocks free\n",
+                      index, info.os_reserved_mb_low, info.os_reserved_mb_high,
+                      (100ull * sfs->os_bavail) / sfs->os_blocks,
+                      (100ull * sfs->os_bfree) / sfs->os_blocks);
+
+               if (size * repeated > available) {
+                       ret = false;
+                       CDEBUG(D_LAYOUT, "low space on ost %d, available %llu "
+                              "< extension size %llu\n", index, available,
+                              extension_size);
+                       break;
+               }
+       }
+       lod_putref(lod, &lod->lod_ost_descs);
+
+       RETURN(ret);
+}
+
+/**
+ * Adjust extents after component removal
+ *
+ * When we remove an extension component, we move the start of the next
+ * component to match the start of the extension component, so no space is left
+ * without layout.
+ *
+ * \param[in] env      execution environment for this thread
+ * \param[in] lo       object
+ * \param[in] max_comp layout component
+ * \param[in] index    index of this component
+ *
+ * \retval             0 on success
+ * \retval             negative errno on error
+ */
+static void lod_sel_adjust_extents(const struct lu_env *env,
+                                  struct lod_object *lo,
+                                  int max_comp, int index)
+{
+       struct lod_layout_component *lod_comp = NULL;
+       struct lod_layout_component *next = NULL;
+       struct lod_layout_component *prev = NULL;
+       __u64 new_start = 0;
+       __u64 start;
+       int i;
+
+       /* Extension space component */
+       lod_comp = &lo->ldo_comp_entries[index];
+       next = &lo->ldo_comp_entries[index + 1];
+       prev = &lo->ldo_comp_entries[index - 1];
+
+       LASSERT(lod_comp != NULL && prev != NULL && next != NULL);
+       LASSERT(lod_comp->llc_flags & LCME_FL_EXTENSION);
+
+       /* Previous is being removed */
+       if (prev && prev->llc_id == LCME_ID_INVAL)
+               new_start = prev->llc_extent.e_start;
+       else
+               new_start = lod_comp->llc_extent.e_start;
+
+       for (i = index + 1; i < max_comp; i++) {
+               lod_comp = &lo->ldo_comp_entries[i];
+
+               start = lod_comp->llc_extent.e_start;
+               lod_comp->llc_extent.e_start = new_start;
+
+               /* We only move zero length extendable components */
+               if (!(start == lod_comp->llc_extent.e_end))
+                       break;
+
+               LASSERT(!(lod_comp->llc_flags & LCME_FL_INIT));
+
+               lod_comp->llc_extent.e_end = new_start;
+       }
+}
+
+/* Calculate the proposed 'new end' for a component we're extending */
+static __u64 lod_extension_new_end(__u64 extension_size, __u64 extent_end,
+                                  __u32 stripe_size, __u64 component_end,
+                                  __u64 extension_end)
+{
+       __u64 new_end;
+
+       LASSERT(extension_size != 0 && stripe_size != 0);
+
+       /* Round up to extension size */
+       if (extent_end == OBD_OBJECT_EOF) {
+               new_end = OBD_OBJECT_EOF;
+       } else {
+               /* Add at least extension_size to the previous component_end,
+                * covering the req layout extent */
+               new_end = max(extent_end - component_end, extension_size);
+               new_end = roundup(new_end, extension_size);
+               new_end += component_end;
+
+               /* Component end must be min stripe size aligned */
+               if (new_end % stripe_size) {
+                       CDEBUG(D_LAYOUT, "new component end is not aligned "
+                              "by the stripe size %u: [%llu, %llu) ext size "
+                              "%llu new end %llu, aligning\n",
+                              stripe_size, component_end, extent_end,
+                              extension_size, new_end);
+                       new_end = roundup(new_end, stripe_size);
+               }
+
+               /* Overflow */
+               if (new_end < extent_end)
+                       new_end = OBD_OBJECT_EOF;
+       }
+
+       /* Don't extend past the end of the extension component */
+       if (new_end > extension_end)
+               new_end = extension_end;
+
+       return new_end;
+}
+
+/* As lod_sel_handler() could be re-entered for the same component several
+ * times, this is the data for the next call. Fields could be changed to
+ * component indexes when needed, (e.g. if there is no need to instantiate
+ * all the previous components up to the current position) to tell the caller
+ * where to start over from. */
+struct sel_data {
+       int sd_force;
+       int sd_repeat;
+};
+
+/**
+ * Process extent updates for a particular layout component
+ *
+ * Handle layout updates for a particular extension space component touched by
+ * a layout update operation.  Core function of self-extending PFL feature.
+ *
+ * In general, this function processes exactly *one* stage of an extension
+ * operation, modifying the layout accordingly, then returns to the caller.
+ * The caller is responsible for restarting processing with the new layout,
+ * which may repeatedly return to this function until the extension updates
+ * are complete.
+ *
+ * This function does one of a few things to the layout:
+ * 1. Extends the component before the current extension space component to
+ * allow it to accomodate the requested operation (if space/policy permit that
+ * component to continue on its current OSTs)
+ *
+ * 2. If extension of the existing component fails, we do one of two things:
+ *    a. If there is a component after the extension space, we remove the
+ *       extension space component, move the start of the next component down
+ *       accordingly, then notify the caller to restart processing w/the new
+ *       layout.
+ *    b. If there is no following component, we try repeating the current
+ *       component, creating a new component using the current one as a
+ *       template (keeping its stripe properties but not specific striping),
+ *       and try assigning striping for this component.  If there is sufficient
+ *       free space on the OSTs chosen for this component, it is instantiated
+ *       and i/o continues there.
+ *
+ *       If there is not sufficient space on the new OSTs, we remove this new
+ *       component & extend the current component.
+ *
+ * Note further that uninited components followed by extension space can be zero
+ * length meaning that we will try to extend them before initializing them, and
+ * if that fails, they will be removed without initialization.
+ *
+ * 3. If we extend to/beyond the end of an extension space component, that
+ * component is exhausted (all of its range has been given to real components),
+ * so we remove it and restart processing.
+ *
+ * \param[in] env              execution environment for this thread
+ * \param[in,out] lo           object to update the layout of
+ * \param[in] extent           layout extent for requested operation, update
+ *                             layout to fit this operation
+ * \param[in] th               transaction handle for this operation
+ * \param[in,out] max_comp     the highest comp for the portion of the layout
+ *                             we are operating on (For FLR, the chosen
+ *                             replica).  Updated because we may remove
+ *                             components.
+ * \param[in] index            index of the extension space component we're
+ *                             working on
+ * \param[in] write            if this is write op
+ * \param[in,out] force                if the extension is to be forced; set here
+                               to force it on the 2nd call for the same
+                               extension component
+ *
+ * \retval     0 on success
+ * \retval     negative errno on error
+ */
+static int lod_sel_handler(const struct lu_env *env,
+                         struct lod_object *lo,
+                         struct lu_extent *extent,
+                         struct thandle *th, int *max_comp,
+                         int index, int write,
+                         struct sel_data *sd)
+{
+       struct lod_device *d = lu2lod_dev(lo->ldo_obj.do_lu.lo_dev);
+       struct lod_thread_info *info = lod_env_info(env);
+       struct lod_layout_component *lod_comp;
+       struct lod_layout_component *prev;
+       struct lod_layout_component *next = NULL;
+       __u64 extension_size;
+       __u64 new_end = 0;
+       bool repeated;
+       int change = 0;
+       int rc = 0;
+       ENTRY;
+
+       /* First component cannot be extension space */
+       if (index == 0) {
+               CERROR("%s: "DFID" first component cannot be extension space\n",
+                      lod2obd(d)->obd_name, PFID(lod_object_fid(lo)));
+               RETURN(-EINVAL);
+       }
+
+       lod_comp = &lo->ldo_comp_entries[index];
+       prev = &lo->ldo_comp_entries[index - 1];
+       if ((index + 1) < *max_comp)
+               next = &lo->ldo_comp_entries[index + 1];
+
+       /* extension size uses the stripe size field as KiB */
+       extension_size = lod_comp->llc_stripe_size * SEL_UNIT_SIZE;
+
+       CDEBUG(D_LAYOUT, "prev start %llu, extension start %llu, extension end"
+              " %llu, extension size %llu\n", prev->llc_extent.e_start,
+              lod_comp->llc_extent.e_start, lod_comp->llc_extent.e_end,
+              extension_size);
+
+       /* Two extension space components cannot be adjacent & extension space
+        * components cannot be init */
+       if ((prev->llc_flags & LCME_FL_EXTENSION) ||
+           !(ergo(next, !(next->llc_flags & LCME_FL_EXTENSION))) ||
+            lod_comp_inited(lod_comp)) {
+               CERROR("%s: "DFID" invalid extension space components\n",
+                      lod2obd(d)->obd_name, PFID(lod_object_fid(lo)));
+               RETURN(-EINVAL);
+       }
+
+       if (!prev->llc_stripe) {
+               CDEBUG(D_LAYOUT, "Previous component not inited\n");
+               info->lti_count = 1;
+               info->lti_comp_idx[0] = index - 1;
+               rc = lod_declare_instantiate_components(env, lo, th);
+               /* ENOSPC tells us we can't use this component.  If there is
+                * a next or we are repeating, we either spill over (next) or
+                * extend the original comp (repeat).  Otherwise, return the
+                * error to the user. */
+               if (rc == -ENOSPC && (next || sd->sd_repeat))
+                       rc = 1;
+               if (rc < 0)
+                       RETURN(rc);
+       }
+
+       if (sd->sd_force == 0 && rc == 0)
+               rc = !lod_sel_osts_allowed(env, lo, index - 1,
+                                          extension_size, extent,
+                                          &lod_comp->llc_extent, write);
+
+       repeated = !!(sd->sd_repeat);
+       sd->sd_repeat = 0;
+       sd->sd_force = 0;
+
+       /* Extend previous component */
+       if (rc == 0) {
+               new_end = lod_extension_new_end(extension_size, extent->e_end,
+                                               prev->llc_stripe_size,
+                                               prev->llc_extent.e_end,
+                                               lod_comp->llc_extent.e_end);
+
+               CDEBUG(D_LAYOUT, "new end %llu\n", new_end);
+               lod_comp->llc_extent.e_start = new_end;
+               prev->llc_extent.e_end = new_end;
+
+               if (prev->llc_extent.e_end == lod_comp->llc_extent.e_end) {
+                       CDEBUG(D_LAYOUT, "Extension component exhausted\n");
+                       lod_comp->llc_id = LCME_ID_INVAL;
+                       change--;
+               }
+       } else {
+               /* rc == 1, failed to extend current component */
+               LASSERT(rc == 1);
+               if (next) {
+                       /* Normal 'spillover' case - Remove the extension
+                        * space component & bring down the start of the next
+                        * component. */
+                       lod_comp->llc_id = LCME_ID_INVAL;
+                       change--;
+                       if (!(prev->llc_flags & LCME_FL_INIT)) {
+                               prev->llc_id = LCME_ID_INVAL;
+                               change--;
+                       }
+                       lod_sel_adjust_extents(env, lo, *max_comp, index);
+               } else if (lod_comp_inited(prev)) {
+                       /* If there is no next, and the previous component is
+                        * INIT'ed, try repeating the previous component. */
+                       LASSERT(repeated == 0);
+                       rc = lod_layout_repeat_comp(env, lo, index - 1);
+                       if (rc < 0)
+                               RETURN(rc);
+                       change++;
+                       /* The previous component is a repeated component.
+                        * Record this so we don't keep trying to repeat it. */
+                       sd->sd_repeat = 1;
+               } else {
+                       /* If the previous component is not INIT'ed, this may
+                        * be a component we have just instantiated but failed
+                        * to extend. Or even a repeated component we failed
+                        * to prepare a striping for. Do not repeat but instead
+                        * remove the repeated component & force the extention
+                        * of the original one */
+                       sd->sd_force = 1;
+                       if (repeated) {
+                               prev->llc_id = LCME_ID_INVAL;
+                               change--;
+                       }
+               }
+       }
+
+       if (change < 0) {
+               rc = lod_layout_del_prep_layout(env, lo, NULL);
+               if (rc < 0)
+                       RETURN(rc);
+               LASSERTF(-rc == change,
+                        "number deleted %d != requested %d\n", -rc,
+                        change);
+       }
+       *max_comp = *max_comp + change;
+
+       /* lod_del_prep_layout reallocates ldo_comp_entries, so we must
+        * refresh these pointers before using them */
+       lod_comp = &lo->ldo_comp_entries[index];
+       prev = &lo->ldo_comp_entries[index - 1];
+       CDEBUG(D_LAYOUT, "After extent updates: prev start %llu, current start "
+              "%llu, current end %llu max_comp %d ldo_comp_cnt %d\n",
+              prev->llc_extent.e_start, lod_comp->llc_extent.e_start,
+              lod_comp->llc_extent.e_end, *max_comp, lo->ldo_comp_cnt);
+
+       /* Layout changed successfully */
+       RETURN(0);
+}
+
+/**
+ * Declare layout extent updates
+ *
+ * Handles extensions.  Identifies extension components touched by current
+ * operation and passes them to processing function.
+ *
+ * Restarts with updated layouts from the processing function until the current
+ * operation no longer touches an extension space component.
+ *
+ * \param[in] env      execution environment for this thread
+ * \param[in,out] lo   object to update the layout of
+ * \param[in] extent   layout extent for requested operation, update layout to
+ *                     fit this operation
+ * \param[in] th       transaction handle for this operation
+ * \param[in] pick     identifies chosen mirror for FLR layouts
+ * \param[in] write    if this is write op
+ *
+ * \retval     1 on layout changed, 0 on no change
+ * \retval     negative errno on error
+ */
+static int lod_declare_update_extents(const struct lu_env *env,
+               struct lod_object *lo, struct lu_extent *extent,
+               struct thandle *th, int pick, int write)
+{
+       struct lod_thread_info *info = lod_env_info(env);
+       struct lod_layout_component *lod_comp;
+       bool layout_changed = false;
+       struct sel_data sd = { 0 };
+       int start_index;
+       int i = 0;
+       int max_comp = 0;
+       int rc = 0, rc2;
+       int change = 0;
+       ENTRY;
+
+       /* This makes us work on the components of the chosen mirror */
+       start_index = lo->ldo_mirrors[pick].lme_start;
+       max_comp = lo->ldo_mirrors[pick].lme_end + 1;
+       if (lo->ldo_flr_state == LCM_FL_NONE)
+               LASSERT(start_index == 0 && max_comp == lo->ldo_comp_cnt);
+
+       CDEBUG(D_LAYOUT, "extent->e_start %llu, extent->e_end %llu\n",
+              extent->e_start, extent->e_end);
+       for (i = start_index; i < max_comp; i++) {
+               lod_comp = &lo->ldo_comp_entries[i];
+
+               /* We've passed all components of interest */
+               if (lod_comp->llc_extent.e_start >= extent->e_end)
+                       break;
+
+               if (lod_comp->llc_flags & LCME_FL_EXTENSION) {
+                       layout_changed = true;
+                       rc = lod_sel_handler(env, lo, extent, th, &max_comp,
+                                            i, write, &sd);
+                       if (rc < 0)
+                               GOTO(out, rc);
+
+                       /* Nothing has changed behind the prev one */
+                       i -= 2;
+                       continue;
+               }
+       }
+
+       /* We may have added or removed components.  If so, we must update the
+        * start & ends of all the mirrors after the current one, and the end
+        * of the current mirror. */
+       change = max_comp - 1 - lo->ldo_mirrors[pick].lme_end;
+       if (change) {
+               lo->ldo_mirrors[pick].lme_end += change;
+               for (i = pick + 1; i < lo->ldo_mirror_count; i++) {
+                       lo->ldo_mirrors[i].lme_start += change;
+                       lo->ldo_mirrors[i].lme_end += change;
+               }
+       }
+
+       EXIT;
+out:
+       /* The amount of components has changed, adjust the lti_comp_idx */
+       rc2 = lod_layout_data_init(info, lo->ldo_comp_cnt);
+
+       return rc < 0 ? rc : rc2 < 0 ? rc2 : layout_changed;
+}
+
+/* If striping is already instantiated or INIT'ed DOM? */
+static bool lod_is_instantiation_needed(struct lod_layout_component *comp)
+{
+       return !(((lov_pattern(comp->llc_pattern) == LOV_PATTERN_MDT) &&
+                 lod_comp_inited(comp)) || comp->llc_stripe);
+}
+
+/**
+ * Declare layout update for a non-FLR layout.
+ *
+ * \param[in] env      execution environment for this thread
+ * \param[in,out] lo   object to update the layout of
+ * \param[in] layout   layout intent for requested operation, "update" is
+ *                     a process of reacting to this
+ * \param[in] buf      buffer containing lov ea (see comment on usage inline)
+ * \param[in] th       transaction handle for this operation
+ *
+ * \retval     0 on success
+ * \retval     negative errno on error
+ */
 static int lod_declare_update_plain(const struct lu_env *env,
                struct lod_object *lo, struct layout_intent *layout,
                const struct lu_buf *buf, struct thandle *th)
@@ -6072,6 +6834,7 @@ static int lod_declare_update_plain(const struct lu_env *env,
        struct lod_device *d = lu2lod_dev(lo->ldo_obj.do_lu.lo_dev);
        struct lod_layout_component *lod_comp;
        struct lov_comp_md_v1 *comp_v1 = NULL;
+       bool layout_changed = false;
        bool replay = false;
        int i, rc;
        ENTRY;
@@ -6107,6 +6870,11 @@ static int lod_declare_update_plain(const struct lu_env *env,
                /* old on-disk EA is stored in info->lti_buf */
                comp_v1 = (struct lov_comp_md_v1 *)info->lti_buf.lb_buf;
                replay = true;
+               layout_changed = true;
+
+               rc = lod_layout_data_init(info, lo->ldo_comp_cnt);
+               if (rc)
+                       GOTO(out, rc);
        } else {
                /* non replay path */
                rc = lod_striping_load(env, lo);
@@ -6119,18 +6887,27 @@ static int lod_declare_update_plain(const struct lu_env *env,
        if (lo->ldo_comp_cnt > 1 &&
            lod_comp->llc_extent.e_end != OBD_OBJECT_EOF &&
            lod_comp->llc_extent.e_end < layout->li_extent.e_end) {
-               CDEBUG(replay ? D_ERROR : D_LAYOUT,
-                      "%s: the defined layout [0, %#llx) does not covers "
-                      "the write range "DEXT"\n",
-                      lod2obd(d)->obd_name, lod_comp->llc_extent.e_end,
-                      PEXT(&layout->li_extent));
+               CDEBUG_LIMIT(replay ? D_ERROR : D_LAYOUT,
+                            "%s: the defined layout [0, %#llx) does not "
+                            "covers the write range "DEXT"\n",
+                            lod2obd(d)->obd_name, lod_comp->llc_extent.e_end,
+                            PEXT(&layout->li_extent));
                GOTO(out, rc = -EINVAL);
        }
 
-       CDEBUG(D_LAYOUT, "%s: "DFID": instantiate components "DEXT"\n",
+       CDEBUG(D_LAYOUT, "%s: "DFID": update components "DEXT"\n",
               lod2obd(d)->obd_name, PFID(lod_object_fid(lo)),
               PEXT(&layout->li_extent));
 
+       if (!replay) {
+               rc = lod_declare_update_extents(env, lo, &layout->li_extent,
+                               th, 0, layout->li_opc == LAYOUT_INTENT_WRITE);
+               if (rc < 0)
+                       GOTO(out, rc);
+               else if (rc)
+                       layout_changed = true;
+       }
+
        /*
         * Iterate ld->ldo_comp_entries, find the component whose extent under
         * the write range and not instantianted.
@@ -6142,7 +6919,8 @@ static int lod_declare_update_plain(const struct lu_env *env,
                        break;
 
                if (!replay) {
-                       if (lod_comp_inited(lod_comp))
+                       /* If striping is instantiated or INIT'ed DOM skip */
+                       if (!lod_is_instantiation_needed(lod_comp))
                                continue;
                } else {
                        /**
@@ -6166,17 +6944,19 @@ static int lod_declare_update_plain(const struct lu_env *env,
 
                LASSERT(info->lti_comp_idx != NULL);
                info->lti_comp_idx[info->lti_count++] = i;
+               layout_changed = true;
        }
 
-       if (info->lti_count == 0)
+       if (!layout_changed)
                RETURN(-EALREADY);
 
        lod_obj_inc_layout_gen(lo);
        rc = lod_declare_instantiate_components(env, lo, th);
+       EXIT;
 out:
        if (rc)
                lod_striping_free(env, lo);
-       RETURN(rc);
+       return rc;
 }
 
 static inline int lod_comp_index(struct lod_object *lo,
@@ -6191,15 +6971,21 @@ static inline int lod_comp_index(struct lod_object *lo,
 /**
  * Stale other mirrors by writing extent.
  */
-static void lod_stale_components(struct lod_object *lo, int primary,
-                                struct lu_extent *extent)
+static int lod_stale_components(const struct lu_env *env, struct lod_object *lo,
+                               int primary, struct lu_extent *extent,
+                               struct thandle *th)
 {
        struct lod_layout_component *pri_comp, *lod_comp;
+       struct lu_extent pri_extent;
+       int rc = 0;
        int i;
+       ENTRY;
 
        /* The writing extent decides which components in the primary
         * are affected... */
        CDEBUG(D_LAYOUT, "primary mirror %d, "DEXT"\n", primary, PEXT(extent));
+
+restart:
        lod_foreach_mirror_comp(pri_comp, lo, primary) {
                if (!lu_extent_is_overlapped(extent, &pri_comp->llc_extent))
                        continue;
@@ -6208,15 +6994,27 @@ static void lod_stale_components(struct lod_object *lo, int primary,
                       lod_comp_index(lo, pri_comp),
                       PEXT(&pri_comp->llc_extent));
 
+               pri_extent.e_start = pri_comp->llc_extent.e_start;
+               pri_extent.e_end = pri_comp->llc_extent.e_end;
+
                for (i = 0; i < lo->ldo_mirror_count; i++) {
                        if (i == primary)
                                continue;
+                       rc = lod_declare_update_extents(env, lo, &pri_extent,
+                                                       th, i, 0);
+                       /* if update_extents changed the layout, it may have
+                        * reallocated the component array, so start over to
+                        * avoid using stale pointers */
+                       if (rc == 1)
+                               goto restart;
+                       if (rc < 0)
+                               RETURN(rc);
 
                        /* ... and then stale other components that are
                         * overlapping with primary components */
                        lod_foreach_mirror_comp(lod_comp, lo, i) {
                                if (!lu_extent_is_overlapped(
-                                                       &pri_comp->llc_extent,
+                                                       &pri_extent,
                                                        &lod_comp->llc_extent))
                                        continue;
 
@@ -6228,6 +7026,8 @@ static void lod_stale_components(struct lod_object *lo, int primary,
                        }
                }
        }
+
+       RETURN(rc);
 }
 
 /**
@@ -6463,6 +7263,7 @@ static int lod_declare_update_rdonly(const struct lu_env *env,
 
        if (mlc->mlc_opc == MD_LAYOUT_WRITE) {
                struct layout_intent *layout = mlc->mlc_intent;
+               int write = layout->li_opc == LAYOUT_INTENT_WRITE;
                int picked;
 
                extent = layout->li_extent;
@@ -6477,6 +7278,12 @@ static int lod_declare_update_rdonly(const struct lu_env *env,
                       PFID(lod_object_fid(lo)),
                       lo->ldo_mirrors[picked].lme_id);
 
+               /* Update extents of primary before staling */
+               rc = lod_declare_update_extents(env, lo, &extent, th, picked,
+                                               write);
+               if (rc < 0)
+                       GOTO(out, rc);
+
                if (layout->li_opc == LAYOUT_INTENT_TRUNC) {
                        /**
                         * trunc transfers [0, size) in the intent extent, we'd
@@ -6487,7 +7294,9 @@ static int lod_declare_update_rdonly(const struct lu_env *env,
                }
 
                /* stale overlapping components from other mirrors */
-               lod_stale_components(lo, picked, &extent);
+               rc = lod_stale_components(env, lo, picked, &extent, th);
+               if (rc < 0)
+                       GOTO(out, rc);
 
                /* restore truncate intent extent */
                if (layout->li_opc == LAYOUT_INTENT_TRUNC)
@@ -6501,7 +7310,7 @@ static int lod_declare_update_rdonly(const struct lu_env *env,
                                                     &lod_comp->llc_extent))
                                break;
 
-                       if (lod_comp_inited(lod_comp))
+                       if (!lod_is_instantiation_needed(lod_comp))
                                continue;
 
                        info->lti_comp_idx[info->lti_count++] =
@@ -6555,7 +7364,7 @@ static int lod_declare_update_rdonly(const struct lu_env *env,
        if (lo->ldo_layout_gen > (LCME_ID_MAX >> 1)) {
                __u32 layout_version;
 
-               cfs_get_random_bytes(&layout_version, sizeof(layout_version));
+               get_random_bytes(&layout_version, sizeof(layout_version));
                lo->ldo_layout_gen = layout_version & 0xffff;
        }
 
@@ -6627,6 +7436,9 @@ static int lod_declare_update_write_pending(const struct lu_env *env,
         * 2. transfer layout version to all objects to close write era. */
 
        if (mlc->mlc_opc == MD_LAYOUT_WRITE) {
+               struct layout_intent *layout = mlc->mlc_intent;
+               int write = layout->li_opc == LAYOUT_INTENT_WRITE;
+
                LASSERT(mlc->mlc_intent != NULL);
 
                extent = mlc->mlc_intent->li_extent;
@@ -6634,6 +7446,12 @@ static int lod_declare_update_write_pending(const struct lu_env *env,
                CDEBUG(D_LAYOUT, DFID": intent to write: "DEXT"\n",
                       PFID(lod_object_fid(lo)), PEXT(&extent));
 
+               /* 1. Update extents of primary before staling */
+               rc = lod_declare_update_extents(env, lo, &extent, th, primary,
+                                               write);
+               if (rc < 0)
+                       GOTO(out, rc);
+
                if (mlc->mlc_intent->li_opc == LAYOUT_INTENT_TRUNC) {
                        /**
                         * trunc transfers [0, size) in the intent extent, we'd
@@ -6642,10 +7460,13 @@ static int lod_declare_update_write_pending(const struct lu_env *env,
                        extent.e_start = extent.e_end;
                        extent.e_end = OBD_OBJECT_EOF;
                }
-               /* 1. stale overlapping components */
-               lod_stale_components(lo, primary, &extent);
 
-               /* 2. find out the components need instantiating.
+               /* 2. stale overlapping components */
+               rc = lod_stale_components(env, lo, primary, &extent, th);
+               if (rc < 0)
+                       GOTO(out, rc);
+
+               /* 3. find the components which need instantiating.
                 * instantiate [0, mlc->mlc_intent->e_end) */
 
                /* restore truncate intent extent */
@@ -6658,7 +7479,7 @@ static int lod_declare_update_write_pending(const struct lu_env *env,
                                                     &lod_comp->llc_extent))
                                break;
 
-                       if (lod_comp_inited(lod_comp))
+                       if (!lod_is_instantiation_needed(lod_comp))
                                continue;
 
                        CDEBUG(D_LAYOUT, "write instantiate %d / %d\n",
@@ -6785,9 +7606,9 @@ static int lod_declare_update_sync_pending(const struct lu_env *env,
                GOTO(out, rc = -EINVAL);
        }
 
-       CDEBUG(D_LAYOUT, DFID": resynced %u/%zu components\n",
+       CDEBUG(D_LAYOUT, DFID": synced %u resynced %u/%zu components\n",
               PFID(lod_object_fid(lo)),
-              resync_components, mlc->mlc_resync_count);
+              sync_components, resync_components, mlc->mlc_resync_count);
 
        lo->ldo_flr_state = LCM_FL_RDONLY;
        lod_obj_inc_layout_gen(lo);
@@ -7002,16 +7823,8 @@ static int lod_object_init(const struct lu_env *env, struct lu_object *lo,
        ENTRY;
 
        rc = lod_fld_lookup(env, lod, lu_object_fid(lo), &idx, &type);
-       if (rc != 0) {
-               /* Note: Sometimes, it will Return EAGAIN here, see
-                * ptrlpc_import_delay_req(), which might confuse
-                * lu_object_find_at() and make it wait there incorrectly.
-                * so we convert it to EIO here.*/
-               if (rc == -EAGAIN)
-                       rc = -EIO;
-
+       if (rc != 0)
                RETURN(rc);
-       }
 
        if (type == LU_SEQ_RANGE_MDT &&
            idx == lu_site2seq(lo->lo_dev->ld_site)->ss_node_id) {