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LU-10629 lod: Clear OST pool with setstripe
[fs/lustre-release.git] / lustre / lod / lod_object.c
index 1254f33..1fac134 100644 (file)
@@ -23,7 +23,7 @@
  * Copyright  2009 Sun Microsystems, Inc. All rights reserved
  * Use is subject to license terms.
  *
- * Copyright (c) 2012, 2016, Intel Corporation.
+ * Copyright (c) 2012, 2017, Intel Corporation.
  */
 /*
  * lustre/lod/lod_object.c
@@ -40,6 +40,8 @@
 
 #define DEBUG_SUBSYSTEM S_MDS
 
+#include <linux/random.h>
+
 #include <obd.h>
 #include <obd_class.h>
 #include <obd_support.h>
@@ -1046,8 +1048,20 @@ static int lod_attr_get(const struct lu_env *env,
        return dt_attr_get(env, dt_object_child(dt), attr);
 }
 
+static inline void lod_adjust_stripe_info(struct lod_layout_component *comp,
+                                         struct lov_desc *desc)
+{
+       if (comp->llc_pattern != LOV_PATTERN_MDT) {
+               if (!comp->llc_stripe_count)
+                       comp->llc_stripe_count =
+                               desc->ld_default_stripe_count;
+       }
+       if (comp->llc_stripe_size <= 0)
+               comp->llc_stripe_size = desc->ld_default_stripe_size;
+}
+
 int lod_obj_for_each_stripe(const struct lu_env *env, struct lod_object *lo,
-                           struct thandle *th, lod_obj_stripe_cb_t cb,
+                           struct thandle *th,
                            struct lod_obj_stripe_cb_data *data)
 {
        struct lod_layout_component *lod_comp;
@@ -1061,13 +1075,23 @@ int lod_obj_for_each_stripe(const struct lu_env *env, struct lod_object *lo,
                if (lod_comp->llc_stripe == NULL)
                        continue;
 
+               /* has stripe but not inited yet, this component has been
+                * declared to be created, but hasn't created yet.
+                */
+               if (!lod_comp_inited(lod_comp))
+                       continue;
+
+               if (data->locd_comp_skip_cb &&
+                   data->locd_comp_skip_cb(env, lo, i, data))
+                       continue;
+
                LASSERT(lod_comp->llc_stripe_count > 0);
                for (j = 0; j < lod_comp->llc_stripe_count; j++) {
                        struct dt_object *dt = lod_comp->llc_stripe[j];
 
                        if (dt == NULL)
                                continue;
-                       rc = cb(env, lo, dt, th, j, data);
+                       rc = data->locd_stripe_cb(env, lo, dt, th, i, j, data);
                        if (rc != 0)
                                RETURN(rc);
                }
@@ -1075,14 +1099,73 @@ int lod_obj_for_each_stripe(const struct lu_env *env, struct lod_object *lo,
        RETURN(0);
 }
 
+static bool lod_obj_attr_set_comp_skip_cb(const struct lu_env *env,
+               struct lod_object *lo, int comp_idx,
+               struct lod_obj_stripe_cb_data *data)
+{
+       struct lod_layout_component *lod_comp = &lo->ldo_comp_entries[comp_idx];
+       bool skipped = false;
+
+       if (!(data->locd_attr->la_valid & LA_LAYOUT_VERSION))
+               return skipped;
+
+       switch (lo->ldo_flr_state) {
+       case LCM_FL_WRITE_PENDING: {
+               int i;
+
+               /* skip stale components */
+               if (lod_comp->llc_flags & LCME_FL_STALE) {
+                       skipped = true;
+                       break;
+               }
+
+               /* skip valid and overlapping components, therefore any
+                * attempts to write overlapped components will never succeed
+                * because client will get EINPROGRESS. */
+               for (i = 0; i < lo->ldo_comp_cnt; i++) {
+                       if (i == comp_idx)
+                               continue;
+
+                       if (lo->ldo_comp_entries[i].llc_flags & LCME_FL_STALE)
+                               continue;
+
+                       if (lu_extent_is_overlapped(&lod_comp->llc_extent,
+                                       &lo->ldo_comp_entries[i].llc_extent)) {
+                               skipped = true;
+                               break;
+                       }
+               }
+               break;
+       }
+       default:
+               LASSERTF(0, "impossible: %d\n", lo->ldo_flr_state);
+       case LCM_FL_SYNC_PENDING:
+               break;
+       }
+
+       CDEBUG(D_LAYOUT, DFID": %s to set component %x to version: %u\n",
+              PFID(lu_object_fid(&lo->ldo_obj.do_lu)),
+              skipped ? "skipped" : "chose", lod_comp->llc_id,
+              data->locd_attr->la_layout_version);
+
+       return skipped;
+}
+
 static inline int
 lod_obj_stripe_attr_set_cb(const struct lu_env *env, struct lod_object *lo,
                           struct dt_object *dt, struct thandle *th,
-                          int stripe_idx, struct lod_obj_stripe_cb_data *data)
+                          int comp_idx, int stripe_idx,
+                          struct lod_obj_stripe_cb_data *data)
 {
        if (data->locd_declare)
                return lod_sub_declare_attr_set(env, dt, data->locd_attr, th);
 
+       if (data->locd_attr->la_valid & LA_LAYOUT_VERSION) {
+               CDEBUG(D_LAYOUT, DFID": set layout version: %u, comp_idx: %d\n",
+                      PFID(lu_object_fid(&dt->do_lu)),
+                      data->locd_attr->la_layout_version, comp_idx);
+       }
+
        return lod_sub_attr_set(env, dt, data->locd_attr, th);
 }
 
@@ -1120,7 +1203,7 @@ static int lod_declare_attr_set(const struct lu_env *env,
         * speed up rename().
         */
        if (!S_ISDIR(dt->do_lu.lo_header->loh_attr)) {
-               if (!(attr->la_valid & (LA_UID | LA_GID | LA_PROJID)))
+               if (!(attr->la_valid & LA_REMOTE_ATTR_SET))
                        RETURN(rc);
 
                if (OBD_FAIL_CHECK(OBD_FAIL_LFSCK_BAD_OWNER))
@@ -1157,12 +1240,12 @@ static int lod_declare_attr_set(const struct lu_env *env,
                                RETURN(rc);
                }
        } else {
-               struct lod_obj_stripe_cb_data data;
+               struct lod_obj_stripe_cb_data data = { { 0 } };
 
                data.locd_attr = attr;
                data.locd_declare = true;
-               rc = lod_obj_for_each_stripe(env, lo, th,
-                               lod_obj_stripe_attr_set_cb, &data);
+               data.locd_stripe_cb = lod_obj_stripe_attr_set_cb;
+               rc = lod_obj_for_each_stripe(env, lo, th, &data);
        }
 
        if (rc)
@@ -1217,7 +1300,7 @@ static int lod_attr_set(const struct lu_env *env,
                RETURN(rc);
 
        if (!S_ISDIR(dt->do_lu.lo_header->loh_attr)) {
-               if (!(attr->la_valid & (LA_UID | LA_GID | LA_PROJID)))
+               if (!(attr->la_valid & LA_REMOTE_ATTR_SET))
                        RETURN(rc);
 
                if (OBD_FAIL_CHECK(OBD_FAIL_LFSCK_BAD_OWNER))
@@ -1229,6 +1312,14 @@ static int lod_attr_set(const struct lu_env *env,
                        RETURN(rc);
        }
 
+       /* FIXME: a tricky case in the code path of mdd_layout_change():
+        * the in-memory striping information has been freed in lod_xattr_set()
+        * due to layout change. It has to load stripe here again. It only
+        * changes flags of layout so declare_attr_set() is still accurate */
+       rc = lod_load_striping_locked(env, lo);
+       if (rc)
+               RETURN(rc);
+
        if (!lod_obj_is_striped(dt))
                RETURN(0);
 
@@ -1249,12 +1340,13 @@ static int lod_attr_set(const struct lu_env *env,
                                break;
                }
        } else {
-               struct lod_obj_stripe_cb_data data;
+               struct lod_obj_stripe_cb_data data = { { 0 } };
 
                data.locd_attr = attr;
                data.locd_declare = false;
-               rc = lod_obj_for_each_stripe(env, lo, th,
-                               lod_obj_stripe_attr_set_cb, &data);
+               data.locd_comp_skip_cb = lod_obj_attr_set_comp_skip_cb;
+               data.locd_stripe_cb = lod_obj_stripe_attr_set_cb;
+               rc = lod_obj_for_each_stripe(env, lo, th, &data);
        }
 
        if (rc)
@@ -1781,10 +1873,12 @@ static int lod_prep_md_striped_create(const struct lu_env *env,
        int                     rc = 0;
        __u32                   i;
        __u32                   j;
+       bool                    is_specific = false;
        ENTRY;
 
        /* The lum has been verifed in lod_verify_md_striping */
-       LASSERT(le32_to_cpu(lum->lum_magic) == LMV_USER_MAGIC);
+       LASSERT(le32_to_cpu(lum->lum_magic) == LMV_USER_MAGIC ||
+               le32_to_cpu(lum->lum_magic) == LMV_USER_MAGIC_SPECIFIC);
        LASSERT(le32_to_cpu(lum->lum_stripe_count) > 0);
 
        stripe_count = le32_to_cpu(lum->lum_stripe_count);
@@ -1800,6 +1894,12 @@ static int lod_prep_md_striped_create(const struct lu_env *env,
        /* Start index must be the master MDT */
        master_index = lu_site2seq(lod2lu_dev(lod)->ld_site)->ss_node_id;
        idx_array[0] = master_index;
+       if (le32_to_cpu(lum->lum_magic) == LMV_USER_MAGIC_SPECIFIC) {
+               is_specific = true;
+               for (i = 1; i < stripe_count; i++)
+                       idx_array[i] = le32_to_cpu(lum->lum_objects[i].lum_mds);
+       }
+
        for (i = 0; i < stripe_count; i++) {
                struct lod_tgt_desc     *tgt = NULL;
                struct dt_object        *dto;
@@ -1818,7 +1918,8 @@ static int lod_prep_md_striped_create(const struct lu_env *env,
                        CDEBUG(D_INFO, "try idx %d, mdt cnt %u, allocated %u\n",
                               idx, lod->lod_remote_mdt_count + 1, i);
 
-                       if (likely(!OBD_FAIL_CHECK(OBD_FAIL_LARGE_STRIPE))) {
+                       if (likely(!is_specific &&
+                                  !OBD_FAIL_CHECK(OBD_FAIL_LARGE_STRIPE))) {
                                /* check whether the idx already exists
                                 * in current allocated array */
                                for (k = 0; k < i; k++) {
@@ -1881,7 +1982,7 @@ static int lod_prep_md_striped_create(const struct lu_env *env,
                       idx, i, PFID(&fid));
                idx_array[i] = idx;
                /* Set the start index for next stripe allocation */
-               if (i < stripe_count - 1)
+               if (!is_specific && i < stripe_count - 1)
                        idx_array[i + 1] = (idx + 1) %
                                           (lod->lod_remote_mdt_count + 1);
                /* tgt_dt and fid must be ready after search avaible OSP
@@ -1954,25 +2055,19 @@ static int lod_declare_xattr_set_lmv(const struct lu_env *env,
                                     struct thandle *th)
 {
        struct lod_object       *lo = lod_dt_obj(dt);
-       struct lod_device       *lod = lu2lod_dev(dt->do_lu.lo_dev);
-       struct lmv_user_md_v1   *lum;
+       struct lmv_user_md_v1   *lum = lum_buf->lb_buf;
        int                     rc;
        ENTRY;
 
-       lum = lum_buf->lb_buf;
        LASSERT(lum != NULL);
 
        CDEBUG(D_INFO, "lum magic = %x count = %u offset = %d\n",
               le32_to_cpu(lum->lum_magic), le32_to_cpu(lum->lum_stripe_count),
               (int)le32_to_cpu(lum->lum_stripe_offset));
 
-       if (le32_to_cpu(lum->lum_stripe_count) == 0)
+       if (lo->ldo_dir_stripe_count == 0)
                GOTO(out, rc = 0);
 
-       rc = lod_verify_md_striping(lod, lum);
-       if (rc != 0)
-               GOTO(out, rc);
-
        /* prepare dir striped objects */
        rc = lod_prep_md_striped_create(env, dt, attr, lum, dof, th);
        if (rc != 0) {
@@ -2017,7 +2112,7 @@ static int lod_dir_declare_xattr_set(const struct lu_env *env,
                if (rc != 0)
                        RETURN(rc);
        } else if (strcmp(name, XATTR_NAME_LOV) == 0) {
-               rc = lod_verify_striping(d, buf, false, 0);
+               rc = lod_verify_striping(d, lo, buf, false);
                if (rc != 0)
                        RETURN(rc);
        }
@@ -2057,10 +2152,11 @@ static int
 lod_obj_stripe_replace_parent_fid_cb(const struct lu_env *env,
                                     struct lod_object *lo,
                                     struct dt_object *dt, struct thandle *th,
-                                    int stripe_idx,
+                                    int comp_idx, int stripe_idx,
                                     struct lod_obj_stripe_cb_data *data)
 {
        struct lod_thread_info *info = lod_env_info(env);
+       struct lod_layout_component *comp = &lo->ldo_comp_entries[comp_idx];
        struct filter_fid *ff = &info->lti_ff;
        struct lu_buf *buf = &info->lti_buf;
        int rc;
@@ -2068,15 +2164,28 @@ lod_obj_stripe_replace_parent_fid_cb(const struct lu_env *env,
        buf->lb_buf = ff;
        buf->lb_len = sizeof(*ff);
        rc = dt_xattr_get(env, dt, buf, XATTR_NAME_FID);
-       if (rc == -ENODATA)
-               return 0;
-
-       if (rc < 0)
+       if (rc < 0) {
+               if (rc == -ENODATA)
+                       return 0;
                return rc;
+       }
 
+       filter_fid_le_to_cpu(ff, ff, sizeof(*ff));
+       if (lu_fid_eq(lu_object_fid(&lo->ldo_obj.do_lu), &ff->ff_parent) &&
+           ff->ff_layout.ol_comp_id == comp->llc_id)
+               return 0;
+
+       /* rewrite filter_fid */
+       memset(ff, 0, sizeof(*ff));
        ff->ff_parent = *lu_object_fid(&lo->ldo_obj.do_lu);
        ff->ff_parent.f_ver = stripe_idx;
-       fid_cpu_to_le(&ff->ff_parent, &ff->ff_parent);
+       ff->ff_layout.ol_stripe_size = comp->llc_stripe_size;
+       ff->ff_layout.ol_stripe_count = comp->llc_stripe_count;
+       ff->ff_layout.ol_comp_id = comp->llc_id;
+       ff->ff_layout.ol_comp_start = comp->llc_extent.e_start;
+       ff->ff_layout.ol_comp_end = comp->llc_extent.e_end;
+       filter_fid_cpu_to_le(ff, ff, sizeof(*ff));
+
        if (data->locd_declare)
                rc = lod_sub_declare_xattr_set(env, dt, buf, XATTR_NAME_FID,
                                               LU_XATTR_REPLACE, th);
@@ -2110,7 +2219,7 @@ static int lod_replace_parent_fid(const struct lu_env *env,
        struct lod_thread_info  *info = lod_env_info(env);
        struct lu_buf *buf = &info->lti_buf;
        struct filter_fid *ff;
-       struct lod_obj_stripe_cb_data data;
+       struct lod_obj_stripe_cb_data data = { { 0 } };
        int rc;
        ENTRY;
 
@@ -2134,9 +2243,8 @@ static int lod_replace_parent_fid(const struct lu_env *env,
        buf->lb_len = info->lti_ea_store_size;
 
        data.locd_declare = declare;
-       rc = lod_obj_for_each_stripe(env, lo, th,
-                                    lod_obj_stripe_replace_parent_fid_cb,
-                                    &data);
+       data.locd_stripe_cb = lod_obj_stripe_replace_parent_fid_cb;
+       rc = lod_obj_for_each_stripe(env, lo, th, &data);
 
        RETURN(rc);
 }
@@ -2218,7 +2326,7 @@ static int lod_declare_layout_add(const struct lu_env *env,
                                  struct thandle *th)
 {
        struct lod_thread_info  *info = lod_env_info(env);
-       struct lod_layout_component *comp_array, *lod_comp;
+       struct lod_layout_component *comp_array, *lod_comp, *old_array;
        struct lod_device       *d = lu2lod_dev(dt->do_lu.lo_dev);
        struct dt_object *next = dt_object_child(dt);
        struct lov_desc         *desc = &d->lod_desc;
@@ -2226,14 +2334,15 @@ static int lod_declare_layout_add(const struct lu_env *env,
        struct lov_user_md_v3   *v3;
        struct lov_comp_md_v1   *comp_v1 = buf->lb_buf;
        __u32   magic;
-       __u64   prev_end;
-       int     i, rc, array_cnt;
+       int     i, rc, array_cnt, old_array_cnt;
        ENTRY;
 
        LASSERT(lo->ldo_is_composite);
 
-       prev_end = lo->ldo_comp_entries[lo->ldo_comp_cnt - 1].llc_extent.e_end;
-       rc = lod_verify_striping(d, buf, false, prev_end);
+       if (lo->ldo_flr_state != LCM_FL_NONE)
+               RETURN(-EBUSY);
+
+       rc = lod_verify_striping(d, lo, buf, false);
        if (rc != 0)
                RETURN(rc);
 
@@ -2266,16 +2375,11 @@ static int lod_declare_layout_add(const struct lu_env *env,
                lod_comp->llc_extent.e_start = ext->e_start;
                lod_comp->llc_extent.e_end = ext->e_end;
                lod_comp->llc_stripe_offset = v1->lmm_stripe_offset;
+               lod_comp->llc_flags = comp_v1->lcm_entries[i].lcme_flags;
 
                lod_comp->llc_stripe_count = v1->lmm_stripe_count;
-               if (!lod_comp->llc_stripe_count ||
-                   lod_comp->llc_stripe_count == (__u16)-1)
-                       lod_comp->llc_stripe_count =
-                               desc->ld_default_stripe_count;
                lod_comp->llc_stripe_size = v1->lmm_stripe_size;
-               if (!lod_comp->llc_stripe_size)
-                       lod_comp->llc_stripe_size =
-                               desc->ld_default_stripe_size;
+               lod_adjust_stripe_info(lod_comp, desc);
 
                if (v1->lmm_magic == LOV_USER_MAGIC_V3) {
                        v3 = (struct lov_user_md_v3 *) v1;
@@ -2288,17 +2392,28 @@ static int lod_declare_layout_add(const struct lu_env *env,
                }
        }
 
-       OBD_FREE(lo->ldo_comp_entries, sizeof(*lod_comp) * lo->ldo_comp_cnt);
+       old_array = lo->ldo_comp_entries;
+       old_array_cnt = lo->ldo_comp_cnt;
+
        lo->ldo_comp_entries = comp_array;
        lo->ldo_comp_cnt = array_cnt;
+
        /* No need to increase layout generation here, it will be increased
         * later when generating component ID for the new components */
 
        info->lti_buf.lb_len = lod_comp_md_size(lo, false);
        rc = lod_sub_declare_xattr_set(env, next, &info->lti_buf,
                                              XATTR_NAME_LOV, 0, th);
-       if (rc)
+       if (rc) {
+               lo->ldo_comp_entries = old_array;
+               lo->ldo_comp_cnt = old_array_cnt;
                GOTO(error, rc);
+       }
+
+       OBD_FREE(old_array, sizeof(*lod_comp) * old_array_cnt);
+
+       LASSERT(lo->ldo_mirror_count == 1);
+       lo->ldo_mirrors[0].lme_end = array_cnt - 1;
 
        RETURN(0);
 
@@ -2340,7 +2455,7 @@ static int lod_declare_layout_set(const struct lu_env *env,
        struct lod_device       *d = lu2lod_dev(dt->do_lu.lo_dev);
        struct lod_object       *lo = lod_dt_obj(dt);
        struct lov_comp_md_v1   *comp_v1 = buf->lb_buf;
-       __u32   magic, id;
+       __u32   magic;
        int     i, j, rc;
        bool    changed = false;
        ENTRY;
@@ -2367,15 +2482,27 @@ static int lod_declare_layout_set(const struct lu_env *env,
        }
 
        for (i = 0; i < comp_v1->lcm_entry_count; i++) {
-               id = comp_v1->lcm_entries[i].lcme_id;
+               __u32 id = comp_v1->lcm_entries[i].lcme_id;
+               __u32 flags = comp_v1->lcm_entries[i].lcme_flags;
+
+               if (flags & LCME_FL_INIT) {
+                       if (changed)
+                               lod_object_free_striping(env, lo);
+                       RETURN(-EINVAL);
+               }
 
                for (j = 0; j < lo->ldo_comp_cnt; j++) {
                        lod_comp = &lo->ldo_comp_entries[j];
-                       if (id == lod_comp->llc_id || id == LCME_ID_ALL) {
-                               lod_comp->llc_flags =
-                                       comp_v1->lcm_entries[i].lcme_flags;
-                               changed = true;
+                       if (id != lod_comp->llc_id)
+                               continue;
+
+                       if (flags & LCME_FL_NEG) {
+                               flags &= ~LCME_FL_NEG;
+                               lod_comp->llc_flags &= ~flags;
+                       } else {
+                               lod_comp->llc_flags |= flags;
                        }
+                       changed = true;
                }
        }
 
@@ -2388,8 +2515,8 @@ static int lod_declare_layout_set(const struct lu_env *env,
        lod_obj_inc_layout_gen(lo);
 
        info->lti_buf.lb_len = lod_comp_md_size(lo, false);
-       rc = lod_sub_declare_xattr_set(env, dt, &info->lti_buf,
-                                      XATTR_NAME_LOV, 0, th);
+       rc = lod_sub_declare_xattr_set(env, dt_object_child(dt), &info->lti_buf,
+                                      XATTR_NAME_LOV, LU_XATTR_REPLACE, th);
        RETURN(rc);
 }
 
@@ -2422,9 +2549,8 @@ static int lod_declare_layout_del(const struct lu_env *env,
 
        LASSERT(lo->ldo_is_composite);
 
-       rc = lod_verify_striping(d, buf, false, 0);
-       if (rc != 0)
-               RETURN(rc);
+       if (lo->ldo_flr_state != LCM_FL_NONE)
+               RETURN(-EBUSY);
 
        magic = comp_v1->lcm_magic;
        if (magic == __swab32(LOV_USER_MAGIC_COMP_V1)) {
@@ -2450,6 +2576,12 @@ static int lod_declare_layout_del(const struct lu_env *env,
                RETURN(-EINVAL);
        }
 
+       if (id == LCME_ID_INVAL && !flags) {
+               CDEBUG(D_LAYOUT, "%s: no id or flags specified.\n",
+                      lod2obd(d)->obd_name);
+               RETURN(-EINVAL);
+       }
+
        if (flags & LCME_FL_NEG) {
                neg_flags = flags & ~LCME_FL_NEG;
                flags = 0;
@@ -2592,6 +2724,238 @@ unlock:
 }
 
 /**
+ * Convert a plain file lov_mds_md to a composite layout.
+ *
+ * \param[in,out] info the thread info::lti_ea_store buffer contains little
+ *                     endian plain file layout
+ *
+ * \retval             0 on success, <0 on failure
+ */
+static int lod_layout_convert(struct lod_thread_info *info)
+{
+       struct lov_mds_md *lmm = info->lti_ea_store;
+       struct lov_mds_md *lmm_save;
+       struct lov_comp_md_v1 *lcm;
+       struct lov_comp_md_entry_v1 *lcme;
+       size_t size;
+       __u32 blob_size;
+       int rc = 0;
+       ENTRY;
+
+       /* realloc buffer to a composite layout which contains one component */
+       blob_size = lov_mds_md_size(le16_to_cpu(lmm->lmm_stripe_count),
+                                   le32_to_cpu(lmm->lmm_magic));
+       size = sizeof(*lcm) + sizeof(*lcme) + blob_size;
+
+       OBD_ALLOC_LARGE(lmm_save, blob_size);
+       if (!lmm_save)
+               GOTO(out, rc = -ENOMEM);
+
+       memcpy(lmm_save, lmm, blob_size);
+
+       if (info->lti_ea_store_size < size) {
+               rc = lod_ea_store_resize(info, size);
+               if (rc)
+                       GOTO(out, rc);
+       }
+
+       lcm = info->lti_ea_store;
+       lcm->lcm_magic = cpu_to_le32(LOV_MAGIC_COMP_V1);
+       lcm->lcm_size = cpu_to_le32(size);
+       lcm->lcm_layout_gen = cpu_to_le32(le16_to_cpu(
+                                               lmm_save->lmm_layout_gen));
+       lcm->lcm_flags = cpu_to_le16(LCM_FL_NONE);
+       lcm->lcm_entry_count = cpu_to_le16(1);
+       lcm->lcm_mirror_count = 0;
+
+       lcme = &lcm->lcm_entries[0];
+       lcme->lcme_flags = cpu_to_le32(LCME_FL_INIT);
+       lcme->lcme_extent.e_start = 0;
+       lcme->lcme_extent.e_end = cpu_to_le64(OBD_OBJECT_EOF);
+       lcme->lcme_offset = cpu_to_le32(sizeof(*lcm) + sizeof(*lcme));
+       lcme->lcme_size = cpu_to_le32(blob_size);
+
+       memcpy((char *)lcm + lcme->lcme_offset, (char *)lmm_save, blob_size);
+
+       EXIT;
+out:
+       if (lmm_save)
+               OBD_FREE_LARGE(lmm_save, blob_size);
+       return rc;
+}
+
+/**
+ * Merge layouts to form a mirrored file.
+ */
+static int lod_declare_layout_merge(const struct lu_env *env,
+               struct dt_object *dt, const struct lu_buf *mbuf,
+               struct thandle *th)
+{
+       struct lod_thread_info  *info = lod_env_info(env);
+       struct lu_buf           *buf = &info->lti_buf;
+       struct lod_object       *lo = lod_dt_obj(dt);
+       struct lov_comp_md_v1   *lcm;
+       struct lov_comp_md_v1   *cur_lcm;
+       struct lov_comp_md_v1   *merge_lcm;
+       struct lov_comp_md_entry_v1     *lcme;
+       size_t size = 0;
+       size_t offset;
+       __u16 cur_entry_count;
+       __u16 merge_entry_count;
+       __u32 id = 0;
+       __u16 mirror_id = 0;
+       __u32 mirror_count;
+       int     rc, i;
+       ENTRY;
+
+       merge_lcm = mbuf->lb_buf;
+       if (mbuf->lb_len < sizeof(*merge_lcm))
+               RETURN(-EINVAL);
+
+       /* must be an existing layout from disk */
+       if (le32_to_cpu(merge_lcm->lcm_magic) != LOV_MAGIC_COMP_V1)
+               RETURN(-EINVAL);
+
+       merge_entry_count = le16_to_cpu(merge_lcm->lcm_entry_count);
+
+       /* do not allow to merge two mirrored files */
+       if (le16_to_cpu(merge_lcm->lcm_mirror_count))
+               RETURN(-EBUSY);
+
+       /* verify the target buffer */
+       rc = lod_get_lov_ea(env, lo);
+       if (rc <= 0)
+               RETURN(rc ? : -ENODATA);
+
+       cur_lcm = info->lti_ea_store;
+       switch (le32_to_cpu(cur_lcm->lcm_magic)) {
+       case LOV_MAGIC_V1:
+       case LOV_MAGIC_V3:
+               rc = lod_layout_convert(info);
+               break;
+       case LOV_MAGIC_COMP_V1:
+               rc = 0;
+               break;
+       default:
+               rc = -EINVAL;
+       }
+       if (rc)
+               RETURN(rc);
+
+       /* info->lti_ea_store could be reallocated in lod_layout_convert() */
+       cur_lcm = info->lti_ea_store;
+       cur_entry_count = le16_to_cpu(cur_lcm->lcm_entry_count);
+
+       /* 'lcm_mirror_count + 1' is the current # of mirrors the file has */
+       mirror_count = le16_to_cpu(cur_lcm->lcm_mirror_count) + 1;
+       if (mirror_count + 1 > LUSTRE_MIRROR_COUNT_MAX)
+               RETURN(-ERANGE);
+
+       /* size of new layout */
+       size = le32_to_cpu(cur_lcm->lcm_size) +
+              le32_to_cpu(merge_lcm->lcm_size) - sizeof(*cur_lcm);
+
+       memset(buf, 0, sizeof(*buf));
+       lu_buf_alloc(buf, size);
+       if (buf->lb_buf == NULL)
+               RETURN(-ENOMEM);
+
+       lcm = buf->lb_buf;
+       memcpy(lcm, cur_lcm, sizeof(*lcm) + cur_entry_count * sizeof(*lcme));
+
+       offset = sizeof(*lcm) +
+                sizeof(*lcme) * (cur_entry_count + merge_entry_count);
+       for (i = 0; i < cur_entry_count; i++) {
+               struct lov_comp_md_entry_v1 *cur_lcme;
+
+               lcme = &lcm->lcm_entries[i];
+               cur_lcme = &cur_lcm->lcm_entries[i];
+
+               lcme->lcme_offset = cpu_to_le32(offset);
+               memcpy((char *)lcm + offset,
+                      (char *)cur_lcm + le32_to_cpu(cur_lcme->lcme_offset),
+                      le32_to_cpu(lcme->lcme_size));
+
+               offset += le32_to_cpu(lcme->lcme_size);
+
+               if (mirror_count == 1) {
+                       /* new mirrored file, create new mirror ID */
+                       id = pflr_id(1, i + 1);
+                       lcme->lcme_id = cpu_to_le32(id);
+               }
+
+               id = MAX(le32_to_cpu(lcme->lcme_id), id);
+       }
+
+       mirror_id = mirror_id_of(id) + 1;
+       for (i = 0; i < merge_entry_count; i++) {
+               struct lov_comp_md_entry_v1 *merge_lcme;
+
+               merge_lcme = &merge_lcm->lcm_entries[i];
+               lcme = &lcm->lcm_entries[cur_entry_count + i];
+
+               *lcme = *merge_lcme;
+               lcme->lcme_offset = cpu_to_le32(offset);
+
+               id = pflr_id(mirror_id, i + 1);
+               lcme->lcme_id = cpu_to_le32(id);
+
+               memcpy((char *)lcm + offset,
+                      (char *)merge_lcm + le32_to_cpu(merge_lcme->lcme_offset),
+                      le32_to_cpu(lcme->lcme_size));
+
+               offset += le32_to_cpu(lcme->lcme_size);
+       }
+
+       /* fixup layout information */
+       lod_obj_inc_layout_gen(lo);
+       lcm->lcm_layout_gen = cpu_to_le32(lo->ldo_layout_gen);
+       lcm->lcm_size = cpu_to_le32(size);
+       lcm->lcm_entry_count = cpu_to_le16(cur_entry_count + merge_entry_count);
+       lcm->lcm_mirror_count = cpu_to_le16(mirror_count);
+       if ((le16_to_cpu(lcm->lcm_flags) & LCM_FL_FLR_MASK) == LCM_FL_NONE)
+               lcm->lcm_flags = cpu_to_le32(LCM_FL_RDONLY);
+
+       LASSERT(dt_write_locked(env, dt_object_child(dt)));
+       lod_object_free_striping(env, lo);
+       rc = lod_parse_striping(env, lo, buf);
+       if (rc)
+               GOTO(out, rc);
+
+       rc = lod_sub_declare_xattr_set(env, dt_object_child(dt), buf,
+                                       XATTR_NAME_LOV, LU_XATTR_REPLACE, th);
+
+out:
+       lu_buf_free(buf);
+       RETURN(rc);
+}
+
+/**
+ * Split layouts, just set the LOVEA with the layout from mbuf.
+ */
+static int lod_declare_layout_split(const struct lu_env *env,
+               struct dt_object *dt, const struct lu_buf *mbuf,
+               struct thandle *th)
+{
+       struct lod_object *lo = lod_dt_obj(dt);
+       struct lov_comp_md_v1 *lcm = mbuf->lb_buf;
+       int rc;
+       ENTRY;
+
+       lod_obj_inc_layout_gen(lo);
+       lcm->lcm_layout_gen = cpu_to_le32(lo->ldo_layout_gen);
+
+       lod_object_free_striping(env, lo);
+       rc = lod_parse_striping(env, lo, mbuf);
+       if (rc)
+               RETURN(rc);
+
+       rc = lod_sub_declare_xattr_set(env, dt_object_child(dt), mbuf,
+                                      XATTR_NAME_LOV, LU_XATTR_REPLACE, th);
+       RETURN(rc);
+}
+
+/**
  * Implementation of dt_object_operations::do_declare_xattr_set.
  *
  * \see dt_object_operations::do_declare_xattr_set() in the API description
@@ -2614,7 +2978,8 @@ static int lod_declare_xattr_set(const struct lu_env *env,
        ENTRY;
 
        mode = dt->do_lu.lo_header->loh_attr & S_IFMT;
-       if ((S_ISREG(mode) || mode == 0) && !(fl & LU_XATTR_REPLACE) &&
+       if ((S_ISREG(mode) || mode == 0) &&
+           !(fl & (LU_XATTR_REPLACE | LU_XATTR_MERGE | LU_XATTR_SPLIT)) &&
            (strcmp(name, XATTR_NAME_LOV) == 0 ||
             strcmp(name, XATTR_LUSTRE_LOV) == 0)) {
                /*
@@ -2636,6 +3001,14 @@ static int lod_declare_xattr_set(const struct lu_env *env,
                        attr->la_mode = S_IFREG;
                }
                rc = lod_declare_striped_create(env, dt, attr, buf, th);
+       } else if (fl & LU_XATTR_MERGE) {
+               LASSERT(strcmp(name, XATTR_NAME_LOV) == 0 ||
+                       strcmp(name, XATTR_LUSTRE_LOV) == 0);
+               rc = lod_declare_layout_merge(env, dt, buf, th);
+       } else if (fl & LU_XATTR_SPLIT) {
+               LASSERT(strcmp(name, XATTR_NAME_LOV) == 0 ||
+                       strcmp(name, XATTR_LUSTRE_LOV) == 0);
+               rc = lod_declare_layout_split(env, dt, buf, th);
        } else if (S_ISREG(mode) &&
                   strlen(name) > strlen(XATTR_LUSTRE_LOV) + 1 &&
                   strncmp(name, XATTR_LUSTRE_LOV,
@@ -3048,6 +3421,7 @@ out:
  * \param[in] env      execution environment
  * \param[in] dt       object
  * \param[in] attr     attributes the stripes will be created with
+ * \param[in] lmu      lmv_user_md if MDT indices are specified
  * \param[in] dof      format of stripes (see OSD API description)
  * \param[in] th       transaction handle
  * \param[in] declare  where to call "declare" or "execute" methods
@@ -3058,6 +3432,7 @@ out:
 static int lod_dir_striping_create_internal(const struct lu_env *env,
                                            struct dt_object *dt,
                                            struct lu_attr *attr,
+                                           const struct lu_buf *lmu,
                                            struct dt_object_format *dof,
                                            struct thandle *th,
                                            bool declare)
@@ -3074,31 +3449,34 @@ static int lod_dir_striping_create_internal(const struct lu_env *env,
 
        if (!LMVEA_DELETE_VALUES(lo->ldo_dir_stripe_count,
                                 lo->ldo_dir_stripe_offset)) {
-               struct lmv_user_md_v1 *v1 = info->lti_ea_store;
-               int stripe_count = lo->ldo_dir_stripe_count;
+               if (!lmu) {
+                       struct lmv_user_md_v1 *v1 = info->lti_ea_store;
+                       int stripe_count = lo->ldo_dir_stripe_count;
 
-               if (info->lti_ea_store_size < sizeof(*v1)) {
-                       rc = lod_ea_store_resize(info, sizeof(*v1));
-                       if (rc != 0)
-                               RETURN(rc);
-                       v1 = info->lti_ea_store;
-               }
+                       if (info->lti_ea_store_size < sizeof(*v1)) {
+                               rc = lod_ea_store_resize(info, sizeof(*v1));
+                               if (rc != 0)
+                                       RETURN(rc);
+                               v1 = info->lti_ea_store;
+                       }
 
-               memset(v1, 0, sizeof(*v1));
-               v1->lum_magic = cpu_to_le32(LMV_USER_MAGIC);
-               v1->lum_stripe_count = cpu_to_le32(stripe_count);
-               v1->lum_stripe_offset =
-                               cpu_to_le32(lo->ldo_dir_stripe_offset);
+                       memset(v1, 0, sizeof(*v1));
+                       v1->lum_magic = cpu_to_le32(LMV_USER_MAGIC);
+                       v1->lum_stripe_count = cpu_to_le32(stripe_count);
+                       v1->lum_stripe_offset =
+                                       cpu_to_le32(lo->ldo_dir_stripe_offset);
 
-               info->lti_buf.lb_buf = v1;
-               info->lti_buf.lb_len = sizeof(*v1);
+                       info->lti_buf.lb_buf = v1;
+                       info->lti_buf.lb_len = sizeof(*v1);
+                       lmu = &info->lti_buf;
+               }
 
                if (declare)
-                       rc = lod_declare_xattr_set_lmv(env, dt, attr,
-                                                      &info->lti_buf, dof, th);
+                       rc = lod_declare_xattr_set_lmv(env, dt, attr, lmu, dof,
+                                                      th);
                else
-                       rc = lod_xattr_set_lmv(env, dt, &info->lti_buf,
-                                              XATTR_NAME_LMV, 0, th);
+                       rc = lod_xattr_set_lmv(env, dt, lmu, XATTR_NAME_LMV, 0,
+                                              th);
                if (rc != 0)
                        RETURN(rc);
        }
@@ -3176,10 +3554,12 @@ static int lod_dir_striping_create_internal(const struct lu_env *env,
 static int lod_declare_dir_striping_create(const struct lu_env *env,
                                           struct dt_object *dt,
                                           struct lu_attr *attr,
+                                          struct lu_buf *lmu,
                                           struct dt_object_format *dof,
                                           struct thandle *th)
 {
-       return lod_dir_striping_create_internal(env, dt, attr, dof, th, true);
+       return lod_dir_striping_create_internal(env, dt, attr, lmu, dof, th,
+                                               true);
 }
 
 static int lod_dir_striping_create(const struct lu_env *env,
@@ -3188,7 +3568,8 @@ static int lod_dir_striping_create(const struct lu_env *env,
                                   struct dt_object_format *dof,
                                   struct thandle *th)
 {
-       return lod_dir_striping_create_internal(env, dt, attr, dof, th, false);
+       return lod_dir_striping_create_internal(env, dt, attr, NULL, dof, th,
+                                               false);
 }
 
 /**
@@ -3319,6 +3700,9 @@ static int lod_layout_del(const struct lu_env *env, struct dt_object *dt,
                         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);
        } else {
                lod_free_comp_entries(lo);
@@ -3345,6 +3729,10 @@ out:
        return rc;
 }
 
+
+static int lod_get_default_lov_striping(const struct lu_env *env,
+                                       struct lod_object *lo,
+                                       struct lod_default_striping *lds);
 /**
  * Implementation of dt_object_operations::do_xattr_set.
  *
@@ -3386,8 +3774,59 @@ static int lod_xattr_set(const struct lu_env *env,
 
        if (S_ISDIR(dt->do_lu.lo_header->loh_attr) &&
            strcmp(name, XATTR_NAME_LOV) == 0) {
-               /* default LOVEA */
-               rc = lod_xattr_set_lov_on_dir(env, dt, buf, name, fl, th);
+               struct lod_thread_info *info = lod_env_info(env);
+               struct lod_default_striping *lds = &info->lti_def_striping;
+               struct lov_user_md_v1 *v1 = buf->lb_buf;
+               char pool[LOV_MAXPOOLNAME + 1];
+               bool is_del;
+
+               /* get existing striping config */
+               rc = lod_get_default_lov_striping(env, lod_dt_obj(dt), lds);
+               if (rc)
+                       RETURN(rc);
+
+               memset(pool, 0, sizeof(pool));
+               if (lds->lds_def_striping_set == 1)
+                       lod_layout_get_pool(lds->lds_def_comp_entries,
+                                           lds->lds_def_comp_cnt, pool,
+                                           sizeof(pool));
+
+               is_del = LOVEA_DELETE_VALUES(v1->lmm_stripe_size,
+                                            v1->lmm_stripe_count,
+                                            v1->lmm_stripe_offset,
+                                            NULL);
+
+               /* Retain the pool name if it is not given */
+               if (v1->lmm_magic == LOV_USER_MAGIC_V1 && pool[0] != '\0' &&
+                       !is_del) {
+                       struct lod_thread_info *info = lod_env_info(env);
+                       struct lov_user_md_v3 *v3  = info->lti_ea_store;
+
+                       memset(v3, 0, sizeof(*v3));
+                       v3->lmm_magic = cpu_to_le32(LOV_USER_MAGIC_V3);
+                       v3->lmm_pattern = cpu_to_le32(v1->lmm_pattern);
+                       v3->lmm_stripe_count =
+                                       cpu_to_le32(v1->lmm_stripe_count);
+                       v3->lmm_stripe_offset =
+                                       cpu_to_le32(v1->lmm_stripe_offset);
+                       v3->lmm_stripe_size = cpu_to_le32(v1->lmm_stripe_size);
+
+                       strlcpy(v3->lmm_pool_name, pool,
+                               sizeof(v3->lmm_pool_name));
+
+                       info->lti_buf.lb_buf = v3;
+                       info->lti_buf.lb_len = sizeof(*v3);
+                       rc = lod_xattr_set_lov_on_dir(env, dt, &info->lti_buf,
+                                                     name, fl, th);
+               } else {
+                       rc = lod_xattr_set_lov_on_dir(env, dt, buf, name,
+                                                     fl, th);
+               }
+
+               if (lds->lds_def_striping_set == 1 &&
+                   lds->lds_def_comp_entries != NULL)
+                       lod_free_def_comp_entries(lds);
+
                RETURN(rc);
        } else if (S_ISDIR(dt->do_lu.lo_header->loh_attr) &&
                   strcmp(name, XATTR_NAME_DEFAULT_LMV) == 0) {
@@ -3566,6 +4005,7 @@ static int lod_get_default_lov_striping(const struct lu_env *env,
        struct lov_user_md_v3 *v3 = NULL;
        struct lov_comp_md_v1 *comp_v1 = NULL;
        __u16   comp_cnt;
+       __u16   mirror_cnt;
        bool    composite;
        int     rc, i;
        ENTRY;
@@ -3599,9 +4039,11 @@ static int lod_get_default_lov_striping(const struct lu_env *env,
                comp_cnt = comp_v1->lcm_entry_count;
                if (comp_cnt == 0)
                        RETURN(-EINVAL);
+               mirror_cnt = comp_v1->lcm_mirror_count + 1;
                composite = true;
        } else {
                comp_cnt = 1;
+               mirror_cnt = 0;
                composite = false;
        }
 
@@ -3611,7 +4053,8 @@ static int lod_get_default_lov_striping(const struct lu_env *env,
                RETURN(rc);
 
        lds->lds_def_comp_cnt = comp_cnt;
-       lds->lds_def_striping_is_composite = composite ? 1 : 0;
+       lds->lds_def_striping_is_composite = composite;
+       lds->lds_def_mirror_cnt = mirror_cnt;
 
        for (i = 0; i < comp_cnt; i++) {
                struct lod_layout_component *lod_comp;
@@ -3747,11 +4190,14 @@ static void lod_striping_from_default(struct lod_object *lo,
        int i, rc;
 
        if (lds->lds_def_striping_set && S_ISREG(mode)) {
-               rc = lod_alloc_comp_entries(lo, lds->lds_def_comp_cnt);
+               rc = lod_alloc_comp_entries(lo, lds->lds_def_mirror_cnt,
+                                           lds->lds_def_comp_cnt);
                if (rc != 0)
                        return;
 
                lo->ldo_is_composite = lds->lds_def_striping_is_composite;
+               if (lds->lds_def_mirror_cnt > 1)
+                       lo->ldo_flr_state = LCM_FL_RDONLY;
 
                for (i = 0; i < lo->ldo_comp_cnt; i++) {
                        struct lod_layout_component *obj_comp =
@@ -3785,13 +4231,7 @@ static void lod_striping_from_default(struct lod_object *lo,
                        if (!lo->ldo_is_composite)
                                continue;
 
-                       if (obj_comp->llc_stripe_count <= 0 &&
-                           obj_comp->llc_pattern != LOV_PATTERN_MDT)
-                               obj_comp->llc_stripe_count =
-                                       desc->ld_default_stripe_count;
-                       if (obj_comp->llc_stripe_size <= 0)
-                               obj_comp->llc_stripe_size =
-                                       desc->ld_default_stripe_size;
+                       lod_adjust_stripe_info(obj_comp, desc);
                }
        } else if (lds->lds_dir_def_striping_set && S_ISDIR(mode)) {
                if (lo->ldo_dir_stripe_count == 0)
@@ -3882,6 +4322,8 @@ static void lod_ah_init(const struct lu_env *env,
                nextc->do_ops->do_ah_init(env, ah, nextp, nextc, child_mode);
 
        if (S_ISDIR(child_mode)) {
+               const struct lmv_user_md_v1 *lum1 = ah->dah_eadata;
+
                /* other default values are 0 */
                lc->ldo_dir_stripe_offset = -1;
 
@@ -3894,10 +4336,13 @@ static void lod_ah_init(const struct lu_env *env,
                        lc->ldo_def_striping = lds;
 
                /* It should always honour the specified stripes */
+               /* Note: old client (< 2.7)might also do lfs mkdir, whose EA
+                * will have old magic. In this case, we should ignore the
+                * stripe count and try to create dir by default stripe.
+                */
                if (ah->dah_eadata != NULL && ah->dah_eadata_len != 0 &&
-                   lod_verify_md_striping(d, ah->dah_eadata) == 0) {
-                       const struct lmv_user_md_v1 *lum1 = ah->dah_eadata;
-
+                   (le32_to_cpu(lum1->lum_magic) == LMV_USER_MAGIC ||
+                    le32_to_cpu(lum1->lum_magic) == LMV_USER_MAGIC_SPECIFIC)) {
                        lc->ldo_dir_stripe_count =
                                le32_to_cpu(lum1->lum_stripe_count);
                        lc->ldo_dir_stripe_offset =
@@ -4006,9 +4451,8 @@ out:
         * in config log, use them.
         */
        if (lod_need_inherit_more(lc, false)) {
-
                if (lc->ldo_comp_cnt == 0) {
-                       rc = lod_alloc_comp_entries(lc, 1);
+                       rc = lod_alloc_comp_entries(lc, 0, 1);
                        if (rc)
                                /* fail to allocate memory, will create a
                                 * non-striped file. */
@@ -4020,12 +4464,7 @@ out:
                LASSERT(!lc->ldo_is_composite);
                lod_comp = &lc->ldo_comp_entries[0];
                desc = &d->lod_desc;
-               if (lod_comp->llc_stripe_count <= 0)
-                       lod_comp->llc_stripe_count =
-                               desc->ld_default_stripe_count;
-               if (lod_comp->llc_stripe_size <= 0)
-                       lod_comp->llc_stripe_size =
-                               desc->ld_default_stripe_size;
+               lod_adjust_stripe_info(lod_comp, desc);
        }
 
        EXIT;
@@ -4057,6 +4496,7 @@ static int lod_declare_init_size(const struct lu_env *env,
        struct lu_attr  *attr = &lod_env_info(env)->lti_attr;
        uint64_t        size, offs;
        int     i, rc, stripe, stripe_count = 0, stripe_size = 0;
+       struct lu_extent size_ext;
        ENTRY;
 
        if (!lod_obj_is_striped(dt))
@@ -4071,6 +4511,7 @@ static int lod_declare_init_size(const struct lu_env *env,
        if (size == 0)
                RETURN(0);
 
+       size_ext = (typeof(size_ext)){ .e_start = size - 1, .e_end = size };
        for (i = 0; i < lo->ldo_comp_cnt; i++) {
                struct lod_layout_component *lod_comp;
                struct lu_extent *extent;
@@ -4081,35 +4522,34 @@ static int lod_declare_init_size(const struct lu_env *env,
                        continue;
 
                extent = &lod_comp->llc_extent;
-               CDEBUG(D_INFO, "%lld [%lld, %lld)\n",
-                      size, extent->e_start, extent->e_end);
+               CDEBUG(D_INFO, "%lld "DEXT"\n", size, PEXT(extent));
                if (!lo->ldo_is_composite ||
-                   (size >= extent->e_start && size < extent->e_end)) {
+                   lu_extent_is_overlapped(extent, &size_ext)) {
                        objects = lod_comp->llc_stripe;
                        stripe_count = lod_comp->llc_stripe_count;
                        stripe_size = lod_comp->llc_stripe_size;
-                       break;
-               }
-       }
-
-       if (stripe_count == 0)
-               RETURN(0);
 
-       LASSERT(objects != NULL && stripe_size != 0);
+                       /* next mirror */
+                       if (stripe_count == 0)
+                               continue;
 
-       /* ll_do_div64(a, b) returns a % b, and a = a / b */
-       ll_do_div64(size, (__u64)stripe_size);
-       stripe = ll_do_div64(size, (__u64)stripe_count);
-       LASSERT(objects[stripe] != NULL);
+                       LASSERT(objects != NULL && stripe_size != 0);
+                       /* ll_do_div64(a, b) returns a % b, and a = a / b */
+                       ll_do_div64(size, (__u64)stripe_size);
+                       stripe = ll_do_div64(size, (__u64)stripe_count);
+                       LASSERT(objects[stripe] != NULL);
 
-       size = size * stripe_size;
-       offs = attr->la_size;
-       size += ll_do_div64(offs, stripe_size);
+                       size = size * stripe_size;
+                       offs = attr->la_size;
+                       size += ll_do_div64(offs, stripe_size);
 
-       attr->la_valid = LA_SIZE;
-       attr->la_size = size;
+                       attr->la_valid = LA_SIZE;
+                       attr->la_size = size;
 
-       rc = lod_sub_declare_attr_set(env, objects[stripe], attr, th);
+                       rc = lod_sub_declare_attr_set(env, objects[stripe],
+                                                     attr, th);
+               }
+       }
 
        RETURN(rc);
 }
@@ -4233,6 +4673,8 @@ static int lod_declare_create(const struct lu_env *env, struct dt_object *dt,
                                                        NULL, th);
        } else if (dof->dof_type == DFT_DIR) {
                struct seq_server_site *ss;
+               struct lu_buf buf = { NULL };
+               struct lu_buf *lmu = NULL;
 
                ss = lu_site2seq(dt->do_lu.lo_dev->ld_site);
 
@@ -4282,9 +4724,14 @@ static int lod_declare_create(const struct lu_env *env, struct dt_object *dt,
                                else
                                        GOTO(out, rc = -EINVAL);
                        }
+               } else if (hint && hint->dah_eadata) {
+                       lmu = &buf;
+                       lmu->lb_buf = (void *)hint->dah_eadata;
+                       lmu->lb_len = hint->dah_eadata_len;
                }
 
-               rc = lod_declare_dir_striping_create(env, dt, attr, dof, th);
+               rc = lod_declare_dir_striping_create(env, dt, attr, lmu, dof,
+                                                    th);
        }
 out:
        /* failed to create striping or to set initial size, let's reset
@@ -4295,6 +4742,53 @@ out:
 }
 
 /**
+ * Generate component ID for new created component.
+ *
+ * \param[in] lo               LOD object
+ * \param[in] comp_idx         index of ldo_comp_entries
+ *
+ * \retval                     component ID on success
+ * \retval                     LCME_ID_INVAL on failure
+ */
+static __u32 lod_gen_component_id(struct lod_object *lo,
+                                 int mirror_id, int comp_idx)
+{
+       struct lod_layout_component *lod_comp;
+       __u32   id, start, end;
+       int     i;
+
+       LASSERT(lo->ldo_comp_entries[comp_idx].llc_id == LCME_ID_INVAL);
+
+       lod_obj_inc_layout_gen(lo);
+       id = lo->ldo_layout_gen;
+       if (likely(id <= SEQ_ID_MAX))
+               RETURN(pflr_id(mirror_id, id & SEQ_ID_MASK));
+
+       /* Layout generation wraps, need to check collisions. */
+       start = id & SEQ_ID_MASK;
+       end = SEQ_ID_MAX;
+again:
+       for (id = start; id <= end; id++) {
+               for (i = 0; i < lo->ldo_comp_cnt; i++) {
+                       lod_comp = &lo->ldo_comp_entries[i];
+                       if (pflr_id(mirror_id, id) == lod_comp->llc_id)
+                               break;
+               }
+               /* Found the ununsed ID */
+               if (i == lo->ldo_comp_cnt)
+                       RETURN(pflr_id(mirror_id, id));
+       }
+       if (end == LCME_ID_MAX) {
+               start = 1;
+               end = min(lo->ldo_layout_gen & LCME_ID_MASK,
+                         (__u32)(LCME_ID_MAX - 1));
+               goto again;
+       }
+
+       RETURN(LCME_ID_INVAL);
+}
+
+/**
  * Creation of a striped regular object.
  *
  * The function is called to create the stripe objects for a regular
@@ -4319,15 +4813,28 @@ int lod_striped_create(const struct lu_env *env, struct dt_object *dt,
 {
        struct lod_layout_component     *lod_comp;
        struct lod_object       *lo = lod_dt_obj(dt);
+       __u16   mirror_id;
        int     rc = 0, i, j;
        ENTRY;
 
        LASSERT(lo->ldo_comp_cnt != 0 && lo->ldo_comp_entries != NULL);
 
+       mirror_id = lo->ldo_mirror_count > 1 ? 1 : 0;
+
        /* create all underlying objects */
        for (i = 0; i < lo->ldo_comp_cnt; i++) {
                lod_comp = &lo->ldo_comp_entries[i];
 
+               if (lod_comp->llc_extent.e_start == 0 && i > 0) /* new mirror */
+                       ++mirror_id;
+
+               if (lod_comp->llc_id == LCME_ID_INVAL) {
+                       lod_comp->llc_id = lod_gen_component_id(lo,
+                                                               mirror_id, i);
+                       if (lod_comp->llc_id == LCME_ID_INVAL)
+                               GOTO(out, rc = -ERANGE);
+               }
+
                if (lod_comp_inited(lod_comp))
                        continue;
 
@@ -4346,19 +4853,24 @@ int lod_striped_create(const struct lu_env *env, struct dt_object *dt,
                        LASSERT(object != NULL);
                        rc = lod_sub_create(env, object, attr, NULL, dof, th);
                        if (rc)
-                               break;
+                               GOTO(out, rc);
                }
                lod_comp_set_init(lod_comp);
        }
 
-       if (rc == 0)
-               rc = lod_generate_and_set_lovea(env, lo, th);
-
-       if (rc == 0)
-               lo->ldo_comp_cached = 1;
-       else
-               lod_object_free_striping(env, lo);
+       rc = lod_fill_mirrors(lo);
+       if (rc)
+               GOTO(out, rc);
 
+       rc = lod_generate_and_set_lovea(env, lo, th);
+       if (rc)
+               GOTO(out, rc);
+
+       lo->ldo_comp_cached = 1;
+       RETURN(0);
+
+out:
+       lod_object_free_striping(env, lo);
        RETURN(rc);
 }
 
@@ -4395,7 +4907,8 @@ static int lod_create(const struct lu_env *env, struct dt_object *dt,
 static inline int
 lod_obj_stripe_destroy_cb(const struct lu_env *env, struct lod_object *lo,
                          struct dt_object *dt, struct thandle *th,
-                         int stripe_idx, struct lod_obj_stripe_cb_data *data)
+                         int comp_idx, int stripe_idx,
+                         struct lod_obj_stripe_cb_data *data)
 {
        if (data->locd_declare)
                return lod_sub_declare_destroy(env, dt, th);
@@ -4487,11 +5000,11 @@ static int lod_declare_destroy(const struct lu_env *env, struct dt_object *dt,
                                break;
                }
        } else {
-               struct lod_obj_stripe_cb_data data;
+               struct lod_obj_stripe_cb_data data = { { 0 } };
 
                data.locd_declare = true;
-               rc = lod_obj_for_each_stripe(env, lo, th,
-                               lod_obj_stripe_destroy_cb, &data);
+               data.locd_stripe_cb = lod_obj_stripe_destroy_cb;
+               rc = lod_obj_for_each_stripe(env, lo, th, &data);
        }
 
        RETURN(rc);
@@ -4577,11 +5090,11 @@ static int lod_destroy(const struct lu_env *env, struct dt_object *dt,
                        }
                }
        } else {
-               struct lod_obj_stripe_cb_data data;
+               struct lod_obj_stripe_cb_data data = { { 0 } };
 
                data.locd_declare = false;
-               rc = lod_obj_for_each_stripe(env, lo, th,
-                               lod_obj_stripe_destroy_cb, &data);
+               data.locd_stripe_cb = lod_obj_stripe_destroy_cb;
+               rc = lod_obj_for_each_stripe(env, lo, th, &data);
        }
 
        RETURN(rc);
@@ -4839,29 +5352,78 @@ static int lod_invalidate(const struct lu_env *env, struct dt_object *dt)
        return dt_invalidate(env, dt_object_child(dt));
 }
 
-static int lod_declare_layout_change(const struct lu_env *env,
-                                    struct dt_object *dt,
-                                    struct layout_intent *layout,
-                                    const struct lu_buf *buf,
-                                    struct thandle *th)
+static int lod_layout_data_init(struct lod_thread_info *info, __u32 comp_cnt)
 {
-       struct lod_thread_info  *info = lod_env_info(env);
-       struct lod_object *lo = lod_dt_obj(dt);
-       struct lod_device *d = lu2lod_dev(dt->do_lu.lo_dev);
-       struct dt_object *next = dt_object_child(dt);
+       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)
+{
+       struct lod_thread_info *info = lod_env_info(env);
        struct ost_pool *inuse = &info->lti_inuse_osts;
+       int i;
+       int rc = 0;
+       ENTRY;
+
+       LASSERT(info->lti_count < lo->ldo_comp_cnt);
+       if (info->lti_count > 0) {
+               /* Prepare inuse array for composite file */
+               rc = lod_prepare_inuse(env, lo);
+               if (rc)
+                       RETURN(rc);
+       }
+
+       for (i = 0; i < info->lti_count; i++) {
+               rc = lod_qos_prep_create(env, lo, NULL, th,
+                                        info->lti_comp_idx[i], inuse);
+               if (rc)
+                       break;
+       }
+
+       if (!rc) {
+               info->lti_buf.lb_len = lod_comp_md_size(lo, false);
+               rc = lod_sub_declare_xattr_set(env, lod_object_child(lo),
+                               &info->lti_buf, XATTR_NAME_LOV, 0, th);
+       }
+
+       RETURN(rc);
+}
+
+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)
+{
+       struct lod_thread_info *info = lod_env_info(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 replay = false;
-       bool need_create = false;
        int i, rc;
        ENTRY;
 
-       if (!S_ISREG(dt->do_lu.lo_header->loh_attr) || !dt_object_exists(dt) ||
-           dt_object_remote(next))
-               RETURN(-EINVAL);
+       LASSERT(lo->ldo_flr_state == LCM_FL_NONE);
 
-       dt_write_lock(env, next, 0);
        /*
         * In case the client is passing lovea, which only happens during
         * the replay of layout intent write RPC for now, we may need to
@@ -4870,9 +5432,9 @@ static int lod_declare_layout_change(const struct lu_env *env,
        if (buf && buf->lb_len)  {
                struct lov_user_md_v1 *v1 = buf->lb_buf;
 
-               if (v1->lmm_magic != (LOV_MAGIC_DEF | LOV_MAGIC_COMP_V1) &&
-                   v1->lmm_magic !=
-                               __swab32(LOV_MAGIC_DEF | LOV_MAGIC_COMP_V1)) {
+               if (v1->lmm_magic != (LOV_MAGIC_DEFINED | LOV_MAGIC_COMP_V1) &&
+                   v1->lmm_magic != __swab32(LOV_MAGIC_DEFINED |
+                                             LOV_MAGIC_COMP_V1)) {
                        CERROR("%s: the replay buffer of layout extend "
                               "(magic %#x) does not contain expected "
                               "composite layout.\n",
@@ -4889,33 +5451,32 @@ static int lod_declare_layout_change(const struct lu_env *env,
                if (rc <= 0)
                        GOTO(out, rc);
                /* old on-disk EA is stored in info->lti_buf */
-               comp_v1 = (struct lov_comp_md_v1 *)&info->lti_buf.lb_buf;
+               comp_v1 = (struct lov_comp_md_v1 *)info->lti_buf.lb_buf;
                replay = true;
        } else {
                /* non replay path */
                rc = lod_load_striping_locked(env, lo);
                if (rc)
                        GOTO(out, rc);
-
-               /* Prepare inuse array for composite file */
-               rc = lod_prepare_inuse(env, lo);
-               if (rc)
-                       GOTO(out, rc);
        }
 
        /* Make sure defined layout covers the requested write range. */
        lod_comp = &lo->ldo_comp_entries[lo->ldo_comp_cnt - 1];
        if (lo->ldo_comp_cnt > 1 &&
            lod_comp->llc_extent.e_end != OBD_OBJECT_EOF &&
-           lod_comp->llc_extent.e_end < layout->li_end) {
+           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 [%#llx, %#llx).\n",
+                      "the write range "DEXT"\n",
                       lod2obd(d)->obd_name, lod_comp->llc_extent.e_end,
-                      layout->li_start, layout->li_end);
+                      PEXT(&layout->li_extent));
                GOTO(out, rc = -EINVAL);
        }
 
+       CDEBUG(D_LAYOUT, "%s: "DFID": instantiate components "DEXT"\n",
+              lod2obd(d)->obd_name, PFID(lod_object_fid(lo)),
+              PEXT(&layout->li_extent));
+
        /*
         * Iterate ld->ldo_comp_entries, find the component whose extent under
         * the write range and not instantianted.
@@ -4923,7 +5484,7 @@ static int lod_declare_layout_change(const struct lu_env *env,
        for (i = 0; i < lo->ldo_comp_cnt; i++) {
                lod_comp = &lo->ldo_comp_entries[i];
 
-               if (lod_comp->llc_extent.e_start >= layout->li_end)
+               if (lod_comp->llc_extent.e_start >= layout->li_extent.e_end)
                        break;
 
                if (!replay) {
@@ -4949,30 +5510,645 @@ static int lod_declare_layout_change(const struct lu_env *env,
                if (lod_comp->llc_pattern & LOV_PATTERN_F_RELEASED)
                        GOTO(out, rc = -EINVAL);
 
-               need_create = true;
+               LASSERT(info->lti_comp_idx != NULL);
+               info->lti_comp_idx[info->lti_count++] = i;
+       }
+
+       if (info->lti_count == 0)
+               RETURN(-EALREADY);
+
+       lod_obj_inc_layout_gen(lo);
+       rc = lod_declare_instantiate_components(env, lo, th);
+out:
+       if (rc)
+               lod_object_free_striping(env, lo);
+       RETURN(rc);
+}
+
+#define lod_foreach_mirror_comp(comp, lo, mirror_idx)                      \
+for (comp = &lo->ldo_comp_entries[lo->ldo_mirrors[mirror_idx].lme_start];  \
+     comp <= &lo->ldo_comp_entries[lo->ldo_mirrors[mirror_idx].lme_end];   \
+     comp++)
+
+static inline int lod_comp_index(struct lod_object *lo,
+                                struct lod_layout_component *lod_comp)
+{
+       LASSERT(lod_comp >= lo->ldo_comp_entries &&
+               lod_comp <= &lo->ldo_comp_entries[lo->ldo_comp_cnt - 1]);
+
+       return lod_comp - lo->ldo_comp_entries;
+}
+
+/**
+ * Stale other mirrors by writing extent.
+ */
+static void lod_stale_components(struct lod_object *lo, int primary,
+                                struct lu_extent *extent)
+{
+       struct lod_layout_component *pri_comp, *lod_comp;
+       int i;
+
+       /* The writing extent decides which components in the primary
+        * are affected... */
+       CDEBUG(D_LAYOUT, "primary mirror %d, "DEXT"\n", primary, PEXT(extent));
+       lod_foreach_mirror_comp(pri_comp, lo, primary) {
+               if (!lu_extent_is_overlapped(extent, &pri_comp->llc_extent))
+                       continue;
+
+               CDEBUG(D_LAYOUT, "primary comp %u "DEXT"\n",
+                      lod_comp_index(lo, pri_comp),
+                      PEXT(&pri_comp->llc_extent));
+
+               for (i = 0; i < lo->ldo_mirror_count; i++) {
+                       if (i == primary)
+                               continue;
+
+                       /* ... 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,
+                                                       &lod_comp->llc_extent))
+                                       continue;
+
+                               CDEBUG(D_LAYOUT, "stale: %u / %u\n",
+                                     i, lod_comp_index(lo, lod_comp));
+
+                               lod_comp->llc_flags |= LCME_FL_STALE;
+                               lo->ldo_mirrors[i].lme_stale = 1;
+                       }
+               }
+       }
+}
+
+/**
+ * check an OST's availability
+ * \param[in] env      execution environment
+ * \param[in] lo       lod object
+ * \param[in] dt       dt object
+ * \param[in] index    mirror index
+ *
+ * \retval     negative if failed
+ * \retval     1 if \a dt is available
+ * \retval     0 if \a dt is not available
+ */
+static inline int lod_check_ost_avail(const struct lu_env *env,
+                                     struct lod_object *lo,
+                                     struct dt_object *dt, int index)
+{
+       struct lod_device *lod = lu2lod_dev(lo->ldo_obj.do_lu.lo_dev);
+       struct lod_tgt_desc *ost;
+       __u32 idx;
+       int type = LU_SEQ_RANGE_OST;
+       int rc;
+
+       rc = lod_fld_lookup(env, lod, lu_object_fid(&dt->do_lu), &idx, &type);
+       if (rc < 0) {
+               CERROR("%s: can't locate "DFID":rc = %d\n",
+                      lod2obd(lod)->obd_name, PFID(lu_object_fid(&dt->do_lu)),
+                      rc);
+               return rc;
+       }
+
+       ost = OST_TGT(lod, idx);
+       if (ost->ltd_statfs.os_state &
+               (OS_STATE_READONLY | OS_STATE_ENOSPC | OS_STATE_ENOINO) ||
+           ost->ltd_active == 0) {
+               CDEBUG(D_LAYOUT, DFID ": mirror %d OST%d unavail, rc = %d\n",
+                      PFID(lod_object_fid(lo)), index, idx, rc);
+               return 0;
+       }
+
+       return 1;
+}
+
+/**
+ * Pick primary mirror for write
+ * \param[in] env      execution environment
+ * \param[in] lo       object
+ * \param[in] extent   write range
+ */
+static int lod_primary_pick(const struct lu_env *env, struct lod_object *lo,
+                           struct lu_extent *extent)
+{
+       struct lod_device *lod = lu2lod_dev(lo->ldo_obj.do_lu.lo_dev);
+       unsigned int seq = 0;
+       struct lod_layout_component *lod_comp;
+       int i, j, rc;
+       int picked = -1, second_pick = -1, third_pick = -1;
+       ENTRY;
+
+       if (OBD_FAIL_CHECK(OBD_FAIL_FLR_RANDOM_PICK_MIRROR)) {
+               get_random_bytes(&seq, sizeof(seq));
+               seq %= lo->ldo_mirror_count;
+       }
+
+       /**
+        * Pick a mirror as the primary, and check the availability of OSTs.
+        *
+        * This algo can be revised later after knowing the topology of
+        * cluster.
+        */
+       lod_qos_statfs_update(env, lod);
+       for (i = 0; i < lo->ldo_mirror_count; i++) {
+               bool ost_avail = true;
+               int index = (i + seq) % lo->ldo_mirror_count;
+
+               if (lo->ldo_mirrors[index].lme_stale) {
+                       CDEBUG(D_LAYOUT, DFID": mirror %d stale\n",
+                              PFID(lod_object_fid(lo)), index);
+                       continue;
+               }
+
+               /* 2nd pick is for the primary mirror containing unavail OST */
+               if (lo->ldo_mirrors[index].lme_primary && second_pick < 0)
+                       second_pick = index;
+
+               /* 3rd pick is for non-primary mirror containing unavail OST */
+               if (second_pick < 0 && third_pick < 0)
+                       third_pick = index;
+
+               /**
+                * we found a non-primary 1st pick, we'd like to find a
+                * potential pirmary mirror.
+                */
+               if (picked >= 0 && !lo->ldo_mirrors[index].lme_primary)
+                       continue;
+
+               /* check the availability of OSTs */
+               lod_foreach_mirror_comp(lod_comp, lo, index) {
+                       if (!lod_comp_inited(lod_comp) || !lod_comp->llc_stripe)
+                               continue;
+
+                       for (j = 0; j < lod_comp->llc_stripe_count; j++) {
+                               struct dt_object *dt = lod_comp->llc_stripe[j];
+
+                               rc = lod_check_ost_avail(env, lo, dt, index);
+                               if (rc < 0)
+                                       RETURN(rc);
+
+                               ost_avail = !!rc;
+                               if (!ost_avail)
+                                       break;
+                       } /* for all dt object in one component */
+                       if (!ost_avail)
+                               break;
+               } /* for all components in a mirror */
+
+               /**
+                * the OSTs where allocated objects locates in the components
+                * of the mirror are available.
+                */
+               if (!ost_avail)
+                       continue;
+
+               /* this mirror has all OSTs available */
+               picked = index;
+
+               /**
+                * primary with all OSTs are available, this is the perfect
+                * 1st pick.
+                */
+               if (lo->ldo_mirrors[index].lme_primary)
+                       break;
+       } /* for all mirrors */
+
+       /* failed to pick a sound mirror, lower our expectation */
+       if (picked < 0)
+               picked = second_pick;
+       if (picked < 0)
+               picked = third_pick;
+       if (picked < 0)
+               RETURN(-ENODATA);
+
+       RETURN(picked);
+}
+
+/**
+ * figure out the components should be instantiated for resync.
+ */
+static int lod_prepare_resync(const struct lu_env *env, struct lod_object *lo,
+                             struct lu_extent *extent)
+{
+       struct lod_thread_info *info = lod_env_info(env);
+       struct lod_layout_component *lod_comp;
+       unsigned int need_sync = 0;
+       int i;
+
+       CDEBUG(D_LAYOUT,
+              DFID": instantiate all stale components in "DEXT"\n",
+              PFID(lod_object_fid(lo)), PEXT(extent));
+
+       /**
+        * instantiate all components within this extent, even non-stale
+        * components.
+        */
+       for (i = 0; i < lo->ldo_mirror_count; i++) {
+               if (!lo->ldo_mirrors[i].lme_stale)
+                       continue;
+
+               lod_foreach_mirror_comp(lod_comp, lo, i) {
+                       if (!lu_extent_is_overlapped(extent,
+                                               &lod_comp->llc_extent))
+                               break;
+
+                       need_sync++;
+
+                       if (lod_comp_inited(lod_comp))
+                               continue;
+
+                       CDEBUG(D_LAYOUT, "resync instantiate %d / %d\n",
+                              i, lod_comp_index(lo, lod_comp));
+                       info->lti_comp_idx[info->lti_count++] =
+                                       lod_comp_index(lo, lod_comp);
+               }
+       }
+
+       return need_sync ? 0 : -EALREADY;
+}
+
+static int lod_declare_update_rdonly(const struct lu_env *env,
+               struct lod_object *lo, struct md_layout_change *mlc,
+               struct thandle *th)
+{
+       struct lod_thread_info *info = lod_env_info(env);
+       struct lu_attr *layout_attr = &info->lti_layout_attr;
+       struct lod_layout_component *lod_comp;
+       struct lu_extent extent = { 0 };
+       int rc;
+       ENTRY;
+
+       LASSERT(lo->ldo_flr_state == LCM_FL_RDONLY);
+       LASSERT(mlc->mlc_opc == MD_LAYOUT_WRITE ||
+               mlc->mlc_opc == MD_LAYOUT_RESYNC);
+       LASSERT(lo->ldo_mirror_count > 0);
+
+       if (mlc->mlc_opc == MD_LAYOUT_WRITE) {
+               struct layout_intent *layout = mlc->mlc_intent;
+               int picked;
+
+               extent = layout->li_extent;
+               CDEBUG(D_LAYOUT, DFID": trying to write :"DEXT"\n",
+                      PFID(lod_object_fid(lo)), PEXT(&extent));
+
+               picked = lod_primary_pick(env, lo, &extent);
+               if (picked < 0)
+                       RETURN(picked);
+
+               CDEBUG(D_LAYOUT, DFID": picked mirror id %u as primary\n",
+                      PFID(lod_object_fid(lo)),
+                      lo->ldo_mirrors[picked].lme_id);
+
+               if (layout->li_opc == LAYOUT_INTENT_TRUNC) {
+                       /**
+                        * trunc transfers [0, size) in the intent extent, we'd
+                        * stale components overlapping [size, eof).
+                        */
+                       extent.e_start = extent.e_end;
+                       extent.e_end = OBD_OBJECT_EOF;
+               }
+
+               /* stale overlapping components from other mirrors */
+               lod_stale_components(lo, picked, &extent);
+
+               /* restore truncate intent extent */
+               if (layout->li_opc == LAYOUT_INTENT_TRUNC)
+                       extent.e_end = extent.e_start;
 
-               rc = lod_qos_prep_create(env, lo, NULL, th, i, inuse);
+               /* instantiate components for the picked mirror, start from 0 */
+               extent.e_start = 0;
+
+               lod_foreach_mirror_comp(lod_comp, lo, picked) {
+                       if (!lu_extent_is_overlapped(&extent,
+                                                    &lod_comp->llc_extent))
+                               break;
+
+                       if (lod_comp_inited(lod_comp))
+                               continue;
+
+                       info->lti_comp_idx[info->lti_count++] =
+                                               lod_comp_index(lo, lod_comp);
+               }
+
+               lo->ldo_flr_state = LCM_FL_WRITE_PENDING;
+       } else { /* MD_LAYOUT_RESYNC */
+               int i;
+
+               /**
+                * could contain multiple non-stale mirrors, so we need to
+                * prep uninited all components assuming any non-stale mirror
+                * could be picked as the primary mirror.
+                */
+               for (i = 0; i < lo->ldo_mirror_count; i++) {
+                       if (lo->ldo_mirrors[i].lme_stale)
+                               continue;
+
+                       lod_foreach_mirror_comp(lod_comp, lo, i) {
+                               if (!lod_comp_inited(lod_comp))
+                                       break;
+
+                               if (extent.e_end < lod_comp->llc_extent.e_end)
+                                       extent.e_end =
+                                               lod_comp->llc_extent.e_end;
+                       }
+               }
+
+               rc = lod_prepare_resync(env, lo, &extent);
                if (rc)
+                       GOTO(out, rc);
+               /* change the file state to SYNC_PENDING */
+               lo->ldo_flr_state = LCM_FL_SYNC_PENDING;
+       }
+
+       /* Reset the layout version once it's becoming too large.
+        * This way it can make sure that the layout version is
+        * monotonously increased in this writing era. */
+       lod_obj_inc_layout_gen(lo);
+       if (lo->ldo_layout_gen > (LCME_ID_MAX >> 1)) {
+               __u32 layout_version;
+
+               cfs_get_random_bytes(&layout_version, sizeof(layout_version));
+               lo->ldo_layout_gen = layout_version & 0xffff;
+       }
+
+       rc = lod_declare_instantiate_components(env, lo, th);
+       if (rc)
+               GOTO(out, rc);
+
+       layout_attr->la_valid = LA_LAYOUT_VERSION;
+       layout_attr->la_layout_version = 0; /* set current version */
+       if (mlc->mlc_opc == MD_LAYOUT_RESYNC)
+               layout_attr->la_layout_version = LU_LAYOUT_RESYNC;
+       rc = lod_declare_attr_set(env, &lo->ldo_obj, layout_attr, th);
+       if (rc)
+               GOTO(out, rc);
+
+out:
+       if (rc)
+               lod_object_free_striping(env, lo);
+       RETURN(rc);
+}
+
+static int lod_declare_update_write_pending(const struct lu_env *env,
+               struct lod_object *lo, struct md_layout_change *mlc,
+               struct thandle *th)
+{
+       struct lod_thread_info *info = lod_env_info(env);
+       struct lu_attr *layout_attr = &info->lti_layout_attr;
+       struct lod_layout_component *lod_comp;
+       struct lu_extent extent = { 0 };
+       int primary = -1;
+       int i;
+       int rc;
+       ENTRY;
+
+       LASSERT(lo->ldo_flr_state == LCM_FL_WRITE_PENDING);
+       LASSERT(mlc->mlc_opc == MD_LAYOUT_WRITE ||
+               mlc->mlc_opc == MD_LAYOUT_RESYNC);
+
+       /* look for the primary mirror */
+       for (i = 0; i < lo->ldo_mirror_count; i++) {
+               if (lo->ldo_mirrors[i].lme_stale)
+                       continue;
+
+               LASSERTF(primary < 0, DFID " has multiple primary: %u / %u",
+                        PFID(lod_object_fid(lo)),
+                        lo->ldo_mirrors[i].lme_id,
+                        lo->ldo_mirrors[primary].lme_id);
+
+               primary = i;
+       }
+       if (primary < 0) {
+               CERROR(DFID ": doesn't have a primary mirror\n",
+                      PFID(lod_object_fid(lo)));
+               GOTO(out, rc = -ENODATA);
+       }
+
+       CDEBUG(D_LAYOUT, DFID": found primary %u\n",
+              PFID(lod_object_fid(lo)), lo->ldo_mirrors[primary].lme_id);
+
+       LASSERT(!lo->ldo_mirrors[primary].lme_stale);
+
+       /* for LAYOUT_WRITE opc, it has to do the following operations:
+        * 1. stale overlapping componets from stale mirrors;
+        * 2. instantiate components of the primary mirror;
+        * 3. transfter layout version to all objects of the primary;
+        *
+        * for LAYOUT_RESYNC opc, it will do:
+        * 1. instantiate components of all stale mirrors;
+        * 2. transfer layout version to all objects to close write era. */
+
+       if (mlc->mlc_opc == MD_LAYOUT_WRITE) {
+               LASSERT(mlc->mlc_intent != NULL);
+
+               extent = mlc->mlc_intent->li_extent;
+
+               CDEBUG(D_LAYOUT, DFID": intent to write: "DEXT"\n",
+                      PFID(lod_object_fid(lo)), PEXT(&extent));
+
+               if (mlc->mlc_intent->li_opc == LAYOUT_INTENT_TRUNC) {
+                       /**
+                        * trunc transfers [0, size) in the intent extent, we'd
+                        * stale components overlapping [size, eof).
+                        */
+                       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.
+                * instantiate [0, mlc->mlc_intent->e_end) */
+
+               /* restore truncate intent extent */
+               if (mlc->mlc_intent->li_opc == LAYOUT_INTENT_TRUNC)
+                       extent.e_end = extent.e_start;
+               extent.e_start = 0;
+
+               lod_foreach_mirror_comp(lod_comp, lo, primary) {
+                       if (!lu_extent_is_overlapped(&extent,
+                                                    &lod_comp->llc_extent))
+                               break;
+
+                       if (lod_comp_inited(lod_comp))
+                               continue;
+
+                       CDEBUG(D_LAYOUT, "write instantiate %d / %d\n",
+                              primary, lod_comp_index(lo, lod_comp));
+                       info->lti_comp_idx[info->lti_count++] =
+                                               lod_comp_index(lo, lod_comp);
+               }
+       } else { /* MD_LAYOUT_RESYNC */
+               lod_foreach_mirror_comp(lod_comp, lo, primary) {
+                       if (!lod_comp_inited(lod_comp))
+                               break;
+
+                       extent.e_end = lod_comp->llc_extent.e_end;
+               }
+
+               rc = lod_prepare_resync(env, lo, &extent);
+               if (rc)
+                       GOTO(out, rc);
+               /* change the file state to SYNC_PENDING */
+               lo->ldo_flr_state = LCM_FL_SYNC_PENDING;
+       }
+
+       rc = lod_declare_instantiate_components(env, lo, th);
+       if (rc)
+               GOTO(out, rc);
+
+       /* 3. transfer layout version to OST objects.
+        * transfer new layout version to OST objects so that stale writes
+        * can be denied. It also ends an era of writing by setting
+        * LU_LAYOUT_RESYNC. Normal client can never use this bit to
+        * send write RPC; only resync RPCs could do it. */
+       layout_attr->la_valid = LA_LAYOUT_VERSION;
+       layout_attr->la_layout_version = 0; /* set current version */
+       if (mlc->mlc_opc == MD_LAYOUT_RESYNC)
+               layout_attr->la_layout_version = LU_LAYOUT_RESYNC;
+       rc = lod_declare_attr_set(env, &lo->ldo_obj, layout_attr, th);
+       if (rc)
+               GOTO(out, rc);
+
+       lod_obj_inc_layout_gen(lo);
+out:
+       if (rc)
+               lod_object_free_striping(env, lo);
+       RETURN(rc);
+}
+
+static int lod_declare_update_sync_pending(const struct lu_env *env,
+               struct lod_object *lo, struct md_layout_change *mlc,
+               struct thandle *th)
+{
+       struct lod_thread_info  *info = lod_env_info(env);
+       unsigned sync_components = 0;
+       unsigned resync_components = 0;
+       int i;
+       int rc;
+       ENTRY;
+
+       LASSERT(lo->ldo_flr_state == LCM_FL_SYNC_PENDING);
+       LASSERT(mlc->mlc_opc == MD_LAYOUT_RESYNC_DONE ||
+               mlc->mlc_opc == MD_LAYOUT_WRITE);
+
+       CDEBUG(D_LAYOUT, DFID ": received op %d in sync pending\n",
+              PFID(lod_object_fid(lo)), mlc->mlc_opc);
+
+       if (mlc->mlc_opc == MD_LAYOUT_WRITE) {
+               CDEBUG(D_LAYOUT, DFID": cocurrent write to sync pending\n",
+                      PFID(lod_object_fid(lo)));
+
+               lo->ldo_flr_state = LCM_FL_WRITE_PENDING;
+               return lod_declare_update_write_pending(env, lo, mlc, th);
+       }
+
+       /* MD_LAYOUT_RESYNC_DONE */
+
+       for (i = 0; i < lo->ldo_comp_cnt; i++) {
+               struct lod_layout_component *lod_comp;
+               int j;
+
+               lod_comp = &lo->ldo_comp_entries[i];
+
+               if (!(lod_comp->llc_flags & LCME_FL_STALE)) {
+                       sync_components++;
+                       continue;
+               }
+
+               for (j = 0; j < mlc->mlc_resync_count; j++) {
+                       if (lod_comp->llc_id != mlc->mlc_resync_ids[j])
+                               continue;
+
+                       mlc->mlc_resync_ids[j] = LCME_ID_INVAL;
+                       lod_comp->llc_flags &= ~LCME_FL_STALE;
+                       resync_components++;
                        break;
+               }
        }
 
-       if (need_create)
-               lod_obj_inc_layout_gen(lo);
-       else
-               GOTO(unlock, rc = -EALREADY);
+       /* valid check */
+       for (i = 0; i < mlc->mlc_resync_count; i++) {
+               if (mlc->mlc_resync_ids[i] == LCME_ID_INVAL)
+                       continue;
 
-       if (!rc) {
-               info->lti_buf.lb_len = lod_comp_md_size(lo, false);
-               rc = lod_sub_declare_xattr_set(env, next, &info->lti_buf,
-                                              XATTR_NAME_LOV, 0, th);
+               CDEBUG(D_LAYOUT, DFID": lcme id %u (%d / %zd) not exist "
+                      "or already synced\n", PFID(lod_object_fid(lo)),
+                      mlc->mlc_resync_ids[i], i, mlc->mlc_resync_count);
+               GOTO(out, rc = -EINVAL);
        }
+
+       if (!sync_components || (mlc->mlc_resync_count && !resync_components)) {
+               CDEBUG(D_LAYOUT, DFID": no mirror in sync\n",
+                      PFID(lod_object_fid(lo)));
+
+               /* tend to return an error code here to prevent
+                * the MDT from setting SoM attribute */
+               GOTO(out, rc = -EINVAL);
+       }
+
+       CDEBUG(D_LAYOUT, DFID": resynced %u/%zu components\n",
+              PFID(lod_object_fid(lo)),
+              resync_components, mlc->mlc_resync_count);
+
+       lo->ldo_flr_state = LCM_FL_RDONLY;
+       lod_obj_inc_layout_gen(lo);
+
+       info->lti_buf.lb_len = lod_comp_md_size(lo, false);
+       rc = lod_sub_declare_xattr_set(env, lod_object_child(lo),
+                                      &info->lti_buf, XATTR_NAME_LOV, 0, th);
+       EXIT;
+
 out:
        if (rc)
                lod_object_free_striping(env, lo);
+       RETURN(rc);
+}
 
-unlock:
-       dt_write_unlock(env, next);
+static int lod_declare_layout_change(const struct lu_env *env,
+               struct dt_object *dt, struct md_layout_change *mlc,
+               struct thandle *th)
+{
+       struct lod_thread_info  *info = lod_env_info(env);
+       struct lod_object *lo = lod_dt_obj(dt);
+       int rc;
+       ENTRY;
+
+       if (!S_ISREG(dt->do_lu.lo_header->loh_attr) || !dt_object_exists(dt) ||
+           dt_object_remote(dt_object_child(dt)))
+               RETURN(-EINVAL);
+
+       lod_write_lock(env, dt, 0);
+       rc = lod_load_striping_locked(env, lo);
+       if (rc)
+               GOTO(out, rc);
+
+       LASSERT(lo->ldo_comp_cnt > 0);
 
+       rc = lod_layout_data_init(info, lo->ldo_comp_cnt);
+       if (rc)
+               GOTO(out, rc);
+
+       switch (lo->ldo_flr_state) {
+       case LCM_FL_NONE:
+               rc = lod_declare_update_plain(env, lo, mlc->mlc_intent,
+                                             &mlc->mlc_buf, th);
+               break;
+       case LCM_FL_RDONLY:
+               rc = lod_declare_update_rdonly(env, lo, mlc, th);
+               break;
+       case LCM_FL_WRITE_PENDING:
+               rc = lod_declare_update_write_pending(env, lo, mlc, th);
+               break;
+       case LCM_FL_SYNC_PENDING:
+               rc = lod_declare_update_sync_pending(env, lo, mlc, th);
+               break;
+       default:
+               rc = -ENOTSUPP;
+               break;
+       }
+out:
+       dt_write_unlock(env, dt);
        RETURN(rc);
 }
 
@@ -4980,12 +6156,20 @@ unlock:
  * Instantiate layout component objects which covers the intent write offset.
  */
 static int lod_layout_change(const struct lu_env *env, struct dt_object *dt,
-                            struct layout_intent *layout,
-                            const struct lu_buf *buf, struct thandle *th)
+                            struct md_layout_change *mlc, struct thandle *th)
 {
        struct lu_attr *attr = &lod_env_info(env)->lti_attr;
+       struct lu_attr *layout_attr = &lod_env_info(env)->lti_layout_attr;
+       struct lod_object *lo = lod_dt_obj(dt);
+       int rc;
 
-       RETURN(lod_striped_create(env, dt, attr, NULL, th));
+       rc = lod_striped_create(env, dt, attr, NULL, th);
+       if (!rc && layout_attr->la_valid & LA_LAYOUT_VERSION) {
+               layout_attr->la_layout_version |= lo->ldo_layout_gen;
+               rc = lod_attr_set(env, dt, layout_attr, th);
+       }
+
+       return rc;
 }
 
 struct dt_object_operations lod_obj_ops = {