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LU-6977 lod: do_index_try should be called first
[fs/lustre-release.git] / lustre / lod / lod_object.c
index e3ad890..ff13bda 100644 (file)
@@ -6,13 +6,13 @@
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 only,
  * as published by the Free Software Foundation.
-
+ *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License version 2 for more details.  A copy is
  * included in the COPYING file that accompanied this code.
-
+ *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  * Copyright  2009 Sun Microsystems, Inc. All rights reserved
  * Use is subject to license terms.
  *
- * Copyright (c) 2012, 2013, Intel Corporation.
+ * Copyright (c) 2012, 2014, Intel Corporation.
  */
 /*
  * lustre/lod/lod_object.c
  *
+ * This file contains implementations of methods for the OSD API
+ * for the Logical Object Device (LOD) layer, which provides a virtual
+ * local OSD object interface to the MDD layer, and abstracts the
+ * addressing of local (OSD) and remote (OSP) objects. The API is
+ * described in the file lustre/include/dt_object.h and in
+ * lustre/doc/osd-api.txt.
+ *
  * Author: Alex Zhuravlev <alexey.zhuravlev@intel.com>
  */
 
 static const char dot[] = ".";
 static const char dotdot[] = "..";
 
-extern struct kmem_cache *lod_object_kmem;
 static const struct dt_body_operations lod_body_lnk_ops;
+static const struct dt_body_operations lod_body_ops;
 
+/**
+ * Implementation of dt_index_operations::dio_lookup
+ *
+ * Used with regular (non-striped) objects.
+ *
+ * \see dt_index_operations::dio_lookup() in the API description for details.
+ */
 static int lod_index_lookup(const struct lu_env *env, struct dt_object *dt,
-                           struct dt_rec *rec, const struct dt_key *key,
-                           struct lustre_capa *capa)
+                           struct dt_rec *rec, const struct dt_key *key)
 {
        struct dt_object *next = dt_object_child(dt);
-       return next->do_index_ops->dio_lookup(env, next, rec, key, capa);
+       return next->do_index_ops->dio_lookup(env, next, rec, key);
 }
 
+/**
+ * Implementation of dt_index_operations::dio_declare_insert.
+ *
+ * Used with regular (non-striped) objects.
+ *
+ * \see dt_index_operations::dio_declare_insert() in the API description
+ * for details.
+ */
 static int lod_declare_index_insert(const struct lu_env *env,
                                    struct dt_object *dt,
                                    const struct dt_rec *rec,
                                    const struct dt_key *key,
-                                   struct thandle *handle)
+                                   struct thandle *th)
 {
-       return dt_declare_insert(env, dt_object_child(dt), rec, key, handle);
+       return lod_sub_object_declare_insert(env, dt_object_child(dt),
+                                            rec, key, th);
 }
 
+/**
+ * Implementation of dt_index_operations::dio_insert.
+ *
+ * Used with regular (non-striped) objects
+ *
+ * \see dt_index_operations::dio_insert() in the API description for details.
+ */
 static int lod_index_insert(const struct lu_env *env,
                            struct dt_object *dt,
                            const struct dt_rec *rec,
                            const struct dt_key *key,
                            struct thandle *th,
-                           struct lustre_capa *capa,
                            int ign)
 {
-       return dt_insert(env, dt_object_child(dt), rec, key, th, capa, ign);
+       return lod_sub_object_index_insert(env, dt_object_child(dt), rec, key,
+                                          th, ign);
 }
 
+/**
+ * Implementation of dt_index_operations::dio_declare_delete.
+ *
+ * Used with regular (non-striped) objects.
+ *
+ * \see dt_index_operations::dio_declare_delete() in the API description
+ * for details.
+ */
 static int lod_declare_index_delete(const struct lu_env *env,
                                    struct dt_object *dt,
                                    const struct dt_key *key,
                                    struct thandle *th)
 {
-       return dt_declare_delete(env, dt_object_child(dt), key, th);
+       return lod_sub_object_declare_delete(env, dt_object_child(dt), key,
+                                            th);
 }
 
+/**
+ * Implementation of dt_index_operations::dio_delete.
+ *
+ * Used with regular (non-striped) objects.
+ *
+ * \see dt_index_operations::dio_delete() in the API description for details.
+ */
 static int lod_index_delete(const struct lu_env *env,
                            struct dt_object *dt,
                            const struct dt_key *key,
-                           struct thandle *th,
-                           struct lustre_capa *capa)
+                           struct thandle *th)
 {
-       return dt_delete(env, dt_object_child(dt), key, th, capa);
+       return lod_sub_object_delete(env, dt_object_child(dt), key, th);
 }
 
+/**
+ * Implementation of dt_it_ops::init.
+ *
+ * Used with regular (non-striped) objects.
+ *
+ * \see dt_it_ops::init() in the API description for details.
+ */
 static struct dt_it *lod_it_init(const struct lu_env *env,
-                                struct dt_object *dt, __u32 attr,
-                                struct lustre_capa *capa)
+                                struct dt_object *dt, __u32 attr)
 {
        struct dt_object        *next = dt_object_child(dt);
        struct lod_it           *it = &lod_env_info(env)->lti_it;
        struct dt_it            *it_next;
 
-
-       it_next = next->do_index_ops->dio_it.init(env, next, attr, capa);
+       it_next = next->do_index_ops->dio_it.init(env, next, attr);
        if (IS_ERR(it_next))
                return it_next;
 
@@ -130,7 +179,14 @@ do {                                                               \
        LASSERT((it)->lit_it != NULL);                          \
 } while (0)
 
-void lod_it_fini(const struct lu_env *env, struct dt_it *di)
+/**
+ * Implementation of dt_index_operations::dio_it.fini.
+ *
+ * Used with regular (non-striped) objects.
+ *
+ * \see dt_index_operations::dio_it.fini() in the API description for details.
+ */
+static void lod_it_fini(const struct lu_env *env, struct dt_it *di)
 {
        struct lod_it *it = (struct lod_it *)di;
 
@@ -142,8 +198,15 @@ void lod_it_fini(const struct lu_env *env, struct dt_it *di)
        it->lit_it = NULL;
 }
 
-int lod_it_get(const struct lu_env *env, struct dt_it *di,
-              const struct dt_key *key)
+/**
+ * Implementation of dt_it_ops::get.
+ *
+ * Used with regular (non-striped) objects.
+ *
+ * \see dt_it_ops::get() in the API description for details.
+ */
+static int lod_it_get(const struct lu_env *env, struct dt_it *di,
+                     const struct dt_key *key)
 {
        const struct lod_it *it = (const struct lod_it *)di;
 
@@ -151,7 +214,14 @@ int lod_it_get(const struct lu_env *env, struct dt_it *di,
        return it->lit_obj->do_index_ops->dio_it.get(env, it->lit_it, key);
 }
 
-void lod_it_put(const struct lu_env *env, struct dt_it *di)
+/**
+ * Implementation of dt_it_ops::put.
+ *
+ * Used with regular (non-striped) objects.
+ *
+ * \see dt_it_ops::put() in the API description for details.
+ */
+static void lod_it_put(const struct lu_env *env, struct dt_it *di)
 {
        struct lod_it *it = (struct lod_it *)di;
 
@@ -159,7 +229,14 @@ void lod_it_put(const struct lu_env *env, struct dt_it *di)
        return it->lit_obj->do_index_ops->dio_it.put(env, it->lit_it);
 }
 
-int lod_it_next(const struct lu_env *env, struct dt_it *di)
+/**
+ * Implementation of dt_it_ops::next.
+ *
+ * Used with regular (non-striped) objects
+ *
+ * \see dt_it_ops::next() in the API description for details.
+ */
+static int lod_it_next(const struct lu_env *env, struct dt_it *di)
 {
        struct lod_it *it = (struct lod_it *)di;
 
@@ -167,7 +244,15 @@ int lod_it_next(const struct lu_env *env, struct dt_it *di)
        return it->lit_obj->do_index_ops->dio_it.next(env, it->lit_it);
 }
 
-struct dt_key *lod_it_key(const struct lu_env *env, const struct dt_it *di)
+/**
+ * Implementation of dt_it_ops::key.
+ *
+ * Used with regular (non-striped) objects.
+ *
+ * \see dt_it_ops::key() in the API description for details.
+ */
+static struct dt_key *lod_it_key(const struct lu_env *env,
+                                const struct dt_it *di)
 {
        const struct lod_it *it = (const struct lod_it *)di;
 
@@ -175,7 +260,14 @@ struct dt_key *lod_it_key(const struct lu_env *env, const struct dt_it *di)
        return it->lit_obj->do_index_ops->dio_it.key(env, it->lit_it);
 }
 
-int lod_it_key_size(const struct lu_env *env, const struct dt_it *di)
+/**
+ * Implementation of dt_it_ops::key_size.
+ *
+ * Used with regular (non-striped) objects.
+ *
+ * \see dt_it_ops::key_size() in the API description for details.
+ */
+static int lod_it_key_size(const struct lu_env *env, const struct dt_it *di)
 {
        struct lod_it *it = (struct lod_it *)di;
 
@@ -183,8 +275,15 @@ int lod_it_key_size(const struct lu_env *env, const struct dt_it *di)
        return it->lit_obj->do_index_ops->dio_it.key_size(env, it->lit_it);
 }
 
-int lod_it_rec(const struct lu_env *env, const struct dt_it *di,
-              struct dt_rec *rec, __u32 attr)
+/**
+ * Implementation of dt_it_ops::rec.
+ *
+ * Used with regular (non-striped) objects.
+ *
+ * \see dt_it_ops::rec() in the API description for details.
+ */
+static int lod_it_rec(const struct lu_env *env, const struct dt_it *di,
+                     struct dt_rec *rec, __u32 attr)
 {
        const struct lod_it *it = (const struct lod_it *)di;
 
@@ -193,8 +292,15 @@ int lod_it_rec(const struct lu_env *env, const struct dt_it *di,
                                                     attr);
 }
 
-int lod_it_rec_size(const struct lu_env *env, const struct dt_it *di,
-                   __u32 attr)
+/**
+ * Implementation of dt_it_ops::rec_size.
+ *
+ * Used with regular (non-striped) objects.
+ *
+ * \see dt_it_ops::rec_size() in the API description for details.
+ */
+static int lod_it_rec_size(const struct lu_env *env, const struct dt_it *di,
+                          __u32 attr)
 {
        const struct lod_it *it = (const struct lod_it *)di;
 
@@ -203,7 +309,14 @@ int lod_it_rec_size(const struct lu_env *env, const struct dt_it *di,
                                                          attr);
 }
 
-__u64 lod_it_store(const struct lu_env *env, const struct dt_it *di)
+/**
+ * Implementation of dt_it_ops::store.
+ *
+ * Used with regular (non-striped) objects.
+ *
+ * \see dt_it_ops::store() in the API description for details.
+ */
+static __u64 lod_it_store(const struct lu_env *env, const struct dt_it *di)
 {
        const struct lod_it *it = (const struct lod_it *)di;
 
@@ -211,7 +324,15 @@ __u64 lod_it_store(const struct lu_env *env, const struct dt_it *di)
        return it->lit_obj->do_index_ops->dio_it.store(env, it->lit_it);
 }
 
-int lod_it_load(const struct lu_env *env, const struct dt_it *di, __u64 hash)
+/**
+ * Implementation of dt_it_ops::load.
+ *
+ * Used with regular (non-striped) objects.
+ *
+ * \see dt_it_ops::load() in the API description for details.
+ */
+static int lod_it_load(const struct lu_env *env, const struct dt_it *di,
+                      __u64 hash)
 {
        const struct lod_it *it = (const struct lod_it *)di;
 
@@ -219,8 +340,15 @@ int lod_it_load(const struct lu_env *env, const struct dt_it *di, __u64 hash)
        return it->lit_obj->do_index_ops->dio_it.load(env, it->lit_it, hash);
 }
 
-int lod_it_key_rec(const struct lu_env *env, const struct dt_it *di,
-                  void *key_rec)
+/**
+ * Implementation of dt_it_ops::key_rec.
+ *
+ * Used with regular (non-striped) objects.
+ *
+ * \see dt_it_ops::rec() in the API description for details.
+ */
+static int lod_it_key_rec(const struct lu_env *env, const struct dt_it *di,
+                         void *key_rec)
 {
        const struct lod_it *it = (const struct lod_it *)di;
 
@@ -252,26 +380,15 @@ static struct dt_index_operations lod_index_ops = {
 };
 
 /**
- * Implementation of dt_index_operations:: dio_it.init
+ * Implementation of dt_it_ops::init.
  *
- * This function is to initialize the iterator for striped directory,
- * basically these lod_striped_it_xxx will just locate the stripe
- * and call the correspondent api of its next lower layer.
+ * Used with striped objects. Internally just initializes the iterator
+ * on the first stripe.
  *
- * \param[in] env      execution environment.
- * \param[in] dt       the striped directory object to be iterated.
- * \param[in] attr     the attribute of iterator, mostly used to indicate
- *                      the entry attribute in the object to be iterated.
- * \param[in] capa     capability(useless in current implementation)
- *
- * \retval     initialized iterator(dt_it) if successful initialize the
- *              iteration. lit_stripe_index will be used to indicate the
- *              current iterate position among stripes.
- * \retval     ERR pointer if initialization is failed.
+ * \see dt_it_ops::init() in the API description for details.
  */
 static struct dt_it *lod_striped_it_init(const struct lu_env *env,
-                                        struct dt_object *dt, __u32 attr,
-                                        struct lustre_capa *capa)
+                                        struct dt_object *dt, __u32 attr)
 {
        struct lod_object       *lo = lod_dt_obj(dt);
        struct dt_object        *next;
@@ -284,7 +401,7 @@ static struct dt_it *lod_striped_it_init(const struct lu_env *env,
        LASSERT(next != NULL);
        LASSERT(next->do_index_ops != NULL);
 
-       it_next = next->do_index_ops->dio_it.init(env, next, attr, capa);
+       it_next = next->do_index_ops->dio_it.init(env, next, attr);
        if (IS_ERR(it_next))
                return it_next;
 
@@ -311,13 +428,11 @@ do {                                                              \
 } while (0)
 
 /**
- * Implementation of dt_index_operations:: dio_it.fini
- *
- * This function is to finish the iterator for striped directory.
+ * Implementation of dt_it_ops::fini.
  *
- * \param[in] env      execution environment.
- * \param[in] di       the iterator for the striped directory
+ * Used with striped objects.
  *
+ * \see dt_it_ops::fini() in the API description for details.
  */
 static void lod_striped_it_fini(const struct lu_env *env, struct dt_it *di)
 {
@@ -325,13 +440,17 @@ static void lod_striped_it_fini(const struct lu_env *env, struct dt_it *di)
        struct lod_object       *lo = lod_dt_obj(it->lit_obj);
        struct dt_object        *next;
 
-       LOD_CHECK_STRIPED_IT(env, it, lo);
+       /* If lit_it == NULL, then it means the sub_it has been finished,
+        * which only happens in failure cases, see lod_striped_it_next() */
+       if (it->lit_it != NULL) {
+               LOD_CHECK_STRIPED_IT(env, it, lo);
 
-       next = lo->ldo_stripe[it->lit_stripe_index];
-       LASSERT(next != NULL);
-       LASSERT(next->do_index_ops != NULL);
+               next = lo->ldo_stripe[it->lit_stripe_index];
+               LASSERT(next != NULL);
+               LASSERT(next->do_index_ops != NULL);
 
-       next->do_index_ops->dio_it.fini(env, it->lit_it);
+               next->do_index_ops->dio_it.fini(env, it->lit_it);
+       }
 
        /* the iterator not in use any more */
        it->lit_obj = NULL;
@@ -340,16 +459,13 @@ static void lod_striped_it_fini(const struct lu_env *env, struct dt_it *di)
 }
 
 /**
- * Implementation of dt_index_operations:: dio_it.get
+ * Implementation of dt_it_ops::get.
  *
- * This function is to position the iterator with given key
+ * Right now it's not used widely, only to reset the iterator to the
+ * initial position. It should be possible to implement a full version
+ * which chooses a correct stripe to be able to position with any key.
  *
- * \param[in] env      execution environment.
- * \param[in] di       the iterator for striped directory.
- * \param[in] key      the key the iterator will be positioned.
- *
- * \retval     0 if successfully position iterator by the key.
- * \retval     negative error if position is failed.
+ * \see dt_it_ops::get() in the API description for details.
  */
 static int lod_striped_it_get(const struct lu_env *env, struct dt_it *di,
                              const struct dt_key *key)
@@ -369,10 +485,11 @@ static int lod_striped_it_get(const struct lu_env *env, struct dt_it *di,
 }
 
 /**
- * Implementation of dt_index_operations:: dio_it.put
+ * Implementation of dt_it_ops::put.
+ *
+ * Used with striped objects.
  *
- * This function is supposed to be the pair of it_get, but currently do
- * nothing. see (osd_it_ea_put or osd_index_it_put)
+ * \see dt_it_ops::put() in the API description for details.
  */
 static void lod_striped_it_put(const struct lu_env *env, struct dt_it *di)
 {
@@ -390,18 +507,12 @@ static void lod_striped_it_put(const struct lu_env *env, struct dt_it *di)
 }
 
 /**
- * Implementation of dt_index_operations:: dio_it.next
+ * Implementation of dt_it_ops::next.
  *
- * This function is to position the iterator to the next entry, if current
- * stripe is finished by checking the return value of next() in current
- * stripe. it will go to next stripe. In the mean time, the sub-iterator
- * for next stripe needs to be initialized.
+ * Used with striped objects. When the end of the current stripe is
+ * reached, the method takes the next stripe's iterator.
  *
- * \param[in] env      execution environment.
- * \param[in] di       the iterator for striped directory.
- *
- * \retval     0 if successfully position iterator to the next entry.
- * \retval     negative error if position is failed.
+ * \see dt_it_ops::next() in the API description for details.
  */
 static int lod_striped_it_next(const struct lu_env *env, struct dt_it *di)
 {
@@ -456,17 +567,17 @@ again:
 
        next->do_index_ops->dio_it.put(env, it->lit_it);
        next->do_index_ops->dio_it.fini(env, it->lit_it);
+       it->lit_it = NULL;
 
+       next = lo->ldo_stripe[it->lit_stripe_index];
+       LASSERT(next != NULL);
        rc = next->do_ops->do_index_try(env, next, &dt_directory_features);
        if (rc != 0)
                RETURN(rc);
 
-       next = lo->ldo_stripe[it->lit_stripe_index];
-       LASSERT(next != NULL);
        LASSERT(next->do_index_ops != NULL);
 
-       it_next = next->do_index_ops->dio_it.init(env, next, it->lit_attr,
-                                                 BYPASS_CAPA);
+       it_next = next->do_index_ops->dio_it.init(env, next, it->lit_attr);
        if (!IS_ERR(it_next)) {
                it->lit_it = it_next;
                goto again;
@@ -478,15 +589,11 @@ again:
 }
 
 /**
- * Implementation of dt_index_operations:: dio_it.key
+ * Implementation of dt_it_ops::key.
  *
- * This function is to get the key of the iterator at current position.
+ * Used with striped objects.
  *
- * \param[in] env      execution environment.
- * \param[in] di       the iterator for striped directory.
- *
- * \retval     key(dt_key) if successfully get the key.
- * \retval     negative error if can not get the key.
+ * \see dt_it_ops::key() in the API description for details.
  */
 static struct dt_key *lod_striped_it_key(const struct lu_env *env,
                                         const struct dt_it *di)
@@ -505,15 +612,11 @@ static struct dt_key *lod_striped_it_key(const struct lu_env *env,
 }
 
 /**
- * Implementation of dt_index_operations:: dio_it.key_size
- *
- * This function is to get the key_size of current key.
+ * Implementation of dt_it_ops::key_size.
  *
- * \param[in] env      execution environment.
- * \param[in] di       the iterator for striped directory.
+ * Used with striped objects.
  *
- * \retval     key_size if successfully get the key_size.
- * \retval     negative error if can not get the key_size.
+ * \see dt_it_ops::size() in the API description for details.
  */
 static int lod_striped_it_key_size(const struct lu_env *env,
                                   const struct dt_it *di)
@@ -532,18 +635,11 @@ static int lod_striped_it_key_size(const struct lu_env *env,
 }
 
 /**
- * Implementation of dt_index_operations:: dio_it.rec
+ * Implementation of dt_it_ops::rec.
  *
- * This function is to get the record at current position.
+ * Used with striped objects.
  *
- * \param[in] env      execution environment.
- * \param[in] di       the iterator for striped directory.
- * \param[in] attr     the attribute of iterator, mostly used to indicate
- *                      the entry attribute in the object to be iterated.
- * \param[out] rec     hold the return record.
- *
- * \retval     0 if successfully get the entry.
- * \retval     negative error if can not get entry.
+ * \see dt_it_ops::rec() in the API description for details.
  */
 static int lod_striped_it_rec(const struct lu_env *env, const struct dt_it *di,
                              struct dt_rec *rec, __u32 attr)
@@ -562,17 +658,11 @@ static int lod_striped_it_rec(const struct lu_env *env, const struct dt_it *di,
 }
 
 /**
- * Implementation of dt_index_operations:: dio_it.rec_size
- *
- * This function is to get the record_size at current record.
+ * Implementation of dt_it_ops::rec_size.
  *
- * \param[in] env      execution environment.
- * \param[in] di       the iterator for striped directory.
- * \param[in] attr     the attribute of iterator, mostly used to indicate
- *                      the entry attribute in the object to be iterated.
+ * Used with striped objects.
  *
- * \retval     rec_size if successfully get the entry size.
- * \retval     negative error if can not get entry size.
+ * \see dt_it_ops::rec_size() in the API description for details.
  */
 static int lod_striped_it_rec_size(const struct lu_env *env,
                                   const struct dt_it *di, __u32 attr)
@@ -591,15 +681,11 @@ static int lod_striped_it_rec_size(const struct lu_env *env,
 }
 
 /**
- * Implementation of dt_index_operations:: dio_it.store
+ * Implementation of dt_it_ops::store.
  *
- * This function will a cookie for current position of the iterator head,
- * so that user can use this cookie to load/start the iterator next time.
+ * Used with striped objects.
  *
- * \param[in] env      execution environment.
- * \param[in] di       the iterator for striped directory.
- *
- * \retval     the cookie.
+ * \see dt_it_ops::store() in the API description for details.
  */
 static __u64 lod_striped_it_store(const struct lu_env *env,
                                  const struct dt_it *di)
@@ -618,17 +704,11 @@ static __u64 lod_striped_it_store(const struct lu_env *env,
 }
 
 /**
- * Implementation of dt_index_operations:: dio_it.load
- *
- * This function will position the iterator with the given hash(usually
- * get from store),
+ * Implementation of dt_it_ops::load.
  *
- * \param[in] env      execution environment.
- * \param[in] di       the iterator for striped directory.
- * \param[in] hash     the given hash.
+ * Used with striped objects.
  *
- * \retval     >0 if successfuly load the iterator to the given position.
- * \retval     <0 if load is failed.
+ * \see dt_it_ops::load() in the API description for details.
  */
 static int lod_striped_it_load(const struct lu_env *env,
                               const struct dt_it *di, __u64 hash)
@@ -705,7 +785,7 @@ int lod_load_lmv_shards(const struct lu_env *env, struct lod_object *lo,
        const struct dt_it_ops  *iops;
        __u32                    stripes;
        __u32                    magic  = le32_to_cpu(lmv1->lmv_magic);
-       size_t                   size;
+       size_t                   lmv1_size;
        int                      rc;
        ENTRY;
 
@@ -721,8 +801,11 @@ int lod_load_lmv_shards(const struct lu_env *env, struct lod_object *lo,
        if (stripes < 1)
                RETURN(0);
 
-       size = lmv_mds_md_size(stripes, magic);
-       if (buf->lb_len < size) {
+       rc = lmv_mds_md_size(stripes, magic);
+       if (rc < 0)
+               RETURN(rc);
+       lmv1_size = rc;
+       if (buf->lb_len < lmv1_size) {
                struct lu_buf tbuf;
 
                if (!resize)
@@ -731,7 +814,7 @@ int lod_load_lmv_shards(const struct lu_env *env, struct lod_object *lo,
                tbuf = *buf;
                buf->lb_buf = NULL;
                buf->lb_len = 0;
-               lu_buf_alloc(buf, size);
+               lu_buf_alloc(buf, lmv1_size);
                lmv1 = buf->lb_buf;
                if (lmv1 == NULL)
                        RETURN(-ENOMEM);
@@ -744,7 +827,7 @@ int lod_load_lmv_shards(const struct lu_env *env, struct lod_object *lo,
 
        memset(&lmv1->lmv_stripe_fids[0], 0, stripes * sizeof(struct lu_fid));
        iops = &obj->do_index_ops->dio_it;
-       it = iops->init(env, obj, LUDA_64BITHASH, BYPASS_CAPA);
+       it = iops->init(env, obj, LUDA_64BITHASH);
        if (IS_ERR(it))
                RETURN(PTR_ERR(it));
 
@@ -776,7 +859,8 @@ int lod_load_lmv_shards(const struct lu_env *env, struct lod_object *lo,
                                goto next;
                }
 
-               len = snprintf(name, FID_LEN + 1, DFID":", PFID(&ent->lde_fid));
+               len = snprintf(name, sizeof(name),
+                              DFID":", PFID(&ent->lde_fid));
                /* The ent->lde_name is composed of ${FID}:${index} */
                if (ent->lde_namelen < len + 1 ||
                    memcmp(ent->lde_name, name, len) != 0) {
@@ -863,21 +947,9 @@ next:
 }
 
 /**
- * Implementation of dt_object_operations:: do_index_try
+ * Implementation of dt_object_operations::do_index_try.
  *
- * This function will try to initialize the index api pointer for the
- * given object, usually it the entry point of the index api. i.e.
- * the index object should be initialized in index_try, then start
- * using index api. For striped directory, it will try to initialize
- * all of its sub_stripes.
- *
- * \param[in] env      execution environment.
- * \param[in] dt       the index object to be initialized.
- * \param[in] feat     the features of this object, for example fixed or
- *                     variable key size etc.
- *
- * \retval     >0 if the initialization is successful.
- * \retval     <0 if the initialization is failed.
+ * \see dt_object_operations::do_index_try() in the API description for details.
  */
 static int lod_index_try(const struct lu_env *env, struct dt_object *dt,
                         const struct dt_index_features *feat)
@@ -917,54 +989,102 @@ static int lod_index_try(const struct lu_env *env, struct dt_object *dt,
        RETURN(rc);
 }
 
+/**
+ * Implementation of dt_object_operations::do_read_lock.
+ *
+ * \see dt_object_operations::do_read_lock() in the API description for details.
+ */
 static void lod_object_read_lock(const struct lu_env *env,
                                 struct dt_object *dt, unsigned role)
 {
        dt_read_lock(env, dt_object_child(dt), role);
 }
 
+/**
+ * Implementation of dt_object_operations::do_write_lock.
+ *
+ * \see dt_object_operations::do_write_lock() in the API description for
+ * details.
+ */
 static void lod_object_write_lock(const struct lu_env *env,
                                  struct dt_object *dt, unsigned role)
 {
        dt_write_lock(env, dt_object_child(dt), role);
 }
 
+/**
+ * Implementation of dt_object_operations::do_read_unlock.
+ *
+ * \see dt_object_operations::do_read_unlock() in the API description for
+ * details.
+ */
 static void lod_object_read_unlock(const struct lu_env *env,
                                   struct dt_object *dt)
 {
        dt_read_unlock(env, dt_object_child(dt));
 }
 
+/**
+ * Implementation of dt_object_operations::do_write_unlock.
+ *
+ * \see dt_object_operations::do_write_unlock() in the API description for
+ * details.
+ */
 static void lod_object_write_unlock(const struct lu_env *env,
                                    struct dt_object *dt)
 {
        dt_write_unlock(env, dt_object_child(dt));
 }
 
+/**
+ * Implementation of dt_object_operations::do_write_locked.
+ *
+ * \see dt_object_operations::do_write_locked() in the API description for
+ * details.
+ */
 static int lod_object_write_locked(const struct lu_env *env,
                                   struct dt_object *dt)
 {
        return dt_write_locked(env, dt_object_child(dt));
 }
 
+/**
+ * Implementation of dt_object_operations::do_attr_get.
+ *
+ * \see dt_object_operations::do_attr_get() in the API description for details.
+ */
 static int lod_attr_get(const struct lu_env *env,
                        struct dt_object *dt,
-                       struct lu_attr *attr,
-                       struct lustre_capa *capa)
+                       struct lu_attr *attr)
 {
        /* Note: for striped directory, client will merge attributes
         * from all of the sub-stripes see lmv_merge_attr(), and there
         * no MDD logic depend on directory nlink/size/time, so we can
         * always use master inode nlink and size for now. */
-       return dt_attr_get(env, dt_object_child(dt), attr, capa);
+       return dt_attr_get(env, dt_object_child(dt), attr);
 }
 
 /**
- * Mark all of sub-stripes dead of the striped directory.
+ * Mark all of the striped directory sub-stripes dead.
+ *
+ * When a striped object is a subject to removal, we have
+ * to mark all the stripes to prevent further access to
+ * them (e.g. create a new file in those). So we mark
+ * all the stripes with LMV_HASH_FLAG_DEAD. The function
+ * can be used to declare the changes and to apply them.
+ * If the object isn't striped, then just return success.
+ *
+ * \param[in] env      execution environment
+ * \param[in] dt       the striped object
+ * \param[in] handle   transaction handle
+ * \param[in] declare  whether to declare the change or apply
+ *
+ * \retval             0 on success
+ * \retval             negative if failed
  **/
 static int lod_mark_dead_object(const struct lu_env *env,
                                struct dt_object *dt,
-                               struct thandle *handle,
+                               struct thandle *th,
                                bool declare)
 {
        struct lod_object       *lo = lod_dt_obj(dt);
@@ -1000,13 +1120,14 @@ static int lod_mark_dead_object(const struct lu_env *env,
                buf.lb_buf = lmv;
                buf.lb_len = sizeof(*lmv);
                if (declare) {
-                       rc = dt_declare_xattr_set(env, lo->ldo_stripe[i], &buf,
-                                                 XATTR_NAME_LMV,
-                                                 LU_XATTR_REPLACE, handle);
+                       rc = lod_sub_object_declare_xattr_set(env,
+                                               lo->ldo_stripe[i], &buf,
+                                               XATTR_NAME_LMV,
+                                               LU_XATTR_REPLACE, th);
                } else {
-                       rc = dt_xattr_set(env, lo->ldo_stripe[i], &buf,
-                                         XATTR_NAME_LMV, LU_XATTR_REPLACE,
-                                         handle, BYPASS_CAPA);
+                       rc = lod_sub_object_xattr_set(env, lo->ldo_stripe[i],
+                                                     &buf, XATTR_NAME_LMV,
+                                                     LU_XATTR_REPLACE, th);
                }
                if (rc != 0)
                        break;
@@ -1015,10 +1136,18 @@ static int lod_mark_dead_object(const struct lu_env *env,
        RETURN(rc);
 }
 
+/**
+ * Implementation of dt_object_operations::do_declare_attr_set.
+ *
+ * If the object is striped, then apply the changes to all the stripes.
+ *
+ * \see dt_object_operations::do_declare_attr_set() in the API description
+ * for details.
+ */
 static int lod_declare_attr_set(const struct lu_env *env,
                                struct dt_object *dt,
                                const struct lu_attr *attr,
-                               struct thandle *handle)
+                               struct thandle *th)
 {
        struct dt_object  *next = dt_object_child(dt);
        struct lod_object *lo = lod_dt_obj(dt);
@@ -1028,14 +1157,14 @@ static int lod_declare_attr_set(const struct lu_env *env,
        /* Set dead object on all other stripes */
        if (attr->la_valid & LA_FLAGS && !(attr->la_valid & ~LA_FLAGS) &&
            attr->la_flags & LUSTRE_SLAVE_DEAD_FL) {
-               rc = lod_mark_dead_object(env, dt, handle, true);
+               rc = lod_mark_dead_object(env, dt, th, true);
                RETURN(rc);
        }
 
        /*
         * declare setattr on the local object
         */
-       rc = dt_declare_attr_set(env, next, attr, handle);
+       rc = lod_sub_object_declare_attr_set(env, next, attr, th);
        if (rc)
                RETURN(rc);
 
@@ -1054,7 +1183,8 @@ static int lod_declare_attr_set(const struct lu_env *env,
                        RETURN(0);
        } else {
                if (!(attr->la_valid & (LA_UID | LA_GID | LA_MODE |
-                                       LA_ATIME | LA_MTIME | LA_CTIME)))
+                                       LA_ATIME | LA_MTIME | LA_CTIME |
+                                       LA_FLAGS)))
                        RETURN(rc);
        }
        /*
@@ -1074,20 +1204,20 @@ static int lod_declare_attr_set(const struct lu_env *env,
         */
        LASSERT(lo->ldo_stripe);
        for (i = 0; i < lo->ldo_stripenr; i++) {
-               if (likely(lo->ldo_stripe[i] != NULL)) {
-                       rc = dt_declare_attr_set(env, lo->ldo_stripe[i], attr,
-                                                handle);
-                       if (rc != 0) {
-                               CERROR("failed declaration: %d\n", rc);
-                               break;
-                       }
-               }
+               if (lo->ldo_stripe[i] == NULL)
+                       continue;
+               rc = lod_sub_object_declare_attr_set(env,
+                                       lo->ldo_stripe[i], attr,
+                                       th);
+               if (rc != 0)
+                       RETURN(rc);
        }
 
        if (OBD_FAIL_CHECK(OBD_FAIL_LFSCK_LOST_STRIPE) &&
            dt_object_exists(next) != 0 &&
            dt_object_remote(next) == 0)
-               dt_declare_xattr_del(env, next, XATTR_NAME_LOV, handle);
+               lod_sub_object_declare_xattr_del(env, next,
+                                               XATTR_NAME_LOV, th);
 
        if (OBD_FAIL_CHECK(OBD_FAIL_LFSCK_CHANGE_STRIPE) &&
            dt_object_exists(next) &&
@@ -1097,18 +1227,26 @@ static int lod_declare_attr_set(const struct lu_env *env,
 
                buf->lb_buf = info->lti_ea_store;
                buf->lb_len = info->lti_ea_store_size;
-               dt_declare_xattr_set(env, next, buf, XATTR_NAME_LOV,
-                                    LU_XATTR_REPLACE, handle);
+               lod_sub_object_declare_xattr_set(env, next, buf,
+                                                XATTR_NAME_LOV,
+                                                LU_XATTR_REPLACE, th);
        }
 
        RETURN(rc);
 }
 
+/**
+ * Implementation of dt_object_operations::do_attr_set.
+ *
+ * If the object is striped, then apply the changes to all or subset of
+ * the stripes depending on the object type and specific attributes.
+ *
+ * \see dt_object_operations::do_attr_set() in the API description for details.
+ */
 static int lod_attr_set(const struct lu_env *env,
                        struct dt_object *dt,
                        const struct lu_attr *attr,
-                       struct thandle *handle,
-                       struct lustre_capa *capa)
+                       struct thandle *th)
 {
        struct dt_object        *next = dt_object_child(dt);
        struct lod_object       *lo = lod_dt_obj(dt);
@@ -1118,14 +1256,14 @@ static int lod_attr_set(const struct lu_env *env,
        /* Set dead object on all other stripes */
        if (attr->la_valid & LA_FLAGS && !(attr->la_valid & ~LA_FLAGS) &&
            attr->la_flags & LUSTRE_SLAVE_DEAD_FL) {
-               rc = lod_mark_dead_object(env, dt, handle, false);
+               rc = lod_mark_dead_object(env, dt, th, false);
                RETURN(rc);
        }
 
        /*
         * apply changes to the local object
         */
-       rc = dt_attr_set(env, next, attr, handle, capa);
+       rc = lod_sub_object_attr_set(env, next, attr, th);
        if (rc)
                RETURN(rc);
 
@@ -1137,7 +1275,8 @@ static int lod_attr_set(const struct lu_env *env,
                        RETURN(0);
        } else {
                if (!(attr->la_valid & (LA_UID | LA_GID | LA_MODE |
-                                       LA_ATIME | LA_MTIME | LA_CTIME)))
+                                       LA_ATIME | LA_MTIME | LA_CTIME |
+                                       LA_FLAGS)))
                        RETURN(rc);
        }
 
@@ -1151,21 +1290,20 @@ static int lod_attr_set(const struct lu_env *env,
        for (i = 0; i < lo->ldo_stripenr; i++) {
                if (unlikely(lo->ldo_stripe[i] == NULL))
                        continue;
+
                if (S_ISDIR(dt->do_lu.lo_header->loh_attr) &&
                    (dt_object_exists(lo->ldo_stripe[i]) == 0))
                        continue;
 
-               rc = dt_attr_set(env, lo->ldo_stripe[i], attr, handle, capa);
-               if (rc != 0) {
-                       CERROR("failed declaration: %d\n", rc);
+               rc = lod_sub_object_attr_set(env, lo->ldo_stripe[i], attr, th);
+               if (rc != 0)
                        break;
-               }
        }
 
        if (OBD_FAIL_CHECK(OBD_FAIL_LFSCK_LOST_STRIPE) &&
            dt_object_exists(next) != 0 &&
            dt_object_remote(next) == 0)
-               dt_xattr_del(env, next, XATTR_NAME_LOV, handle, BYPASS_CAPA);
+               rc = lod_sub_object_xattr_del(env, next, XATTR_NAME_LOV, th);
 
        if (OBD_FAIL_CHECK(OBD_FAIL_LFSCK_CHANGE_STRIPE) &&
            dt_object_exists(next) &&
@@ -1196,23 +1334,31 @@ static int lod_attr_set(const struct lu_env *env,
                fid->f_oid--;
                fid_to_ostid(fid, oi);
                ostid_cpu_to_le(oi, &objs->l_ost_oi);
-               dt_xattr_set(env, next, buf, XATTR_NAME_LOV,
-                            LU_XATTR_REPLACE, handle, BYPASS_CAPA);
+
+               rc = lod_sub_object_xattr_set(env, next, buf, XATTR_NAME_LOV,
+                                             LU_XATTR_REPLACE, th);
        }
 
        RETURN(rc);
 }
 
+/**
+ * Implementation of dt_object_operations::do_xattr_get.
+ *
+ * If LOV EA is requested from the root object and it's not
+ * found, then return default striping for the filesystem.
+ *
+ * \see dt_object_operations::do_xattr_get() in the API description for details.
+ */
 static int lod_xattr_get(const struct lu_env *env, struct dt_object *dt,
-                        struct lu_buf *buf, const char *name,
-                        struct lustre_capa *capa)
+                        struct lu_buf *buf, const char *name)
 {
        struct lod_thread_info  *info = lod_env_info(env);
        struct lod_device       *dev = lu2lod_dev(dt->do_lu.lo_dev);
        int                      rc, is_root;
        ENTRY;
 
-       rc = dt_xattr_get(env, dt_object_child(dt), buf, name, capa);
+       rc = dt_xattr_get(env, dt_object_child(dt), buf, name);
        if (strcmp(name, XATTR_NAME_LMV) == 0) {
                struct lmv_mds_md_v1    *lmv1;
                int                      rc1 = 0;
@@ -1229,7 +1375,7 @@ static int lod_xattr_get(const struct lu_env *env, struct dt_object *dt,
                        info->lti_buf.lb_buf = info->lti_key;
                        info->lti_buf.lb_len = sizeof(*lmv1);
                        rc = dt_xattr_get(env, dt_object_child(dt),
-                                         &info->lti_buf, name, capa);
+                                         &info->lti_buf, name);
                        if (unlikely(rc != sizeof(*lmv1)))
                                RETURN(rc = rc > 0 ? -EINVAL : rc);
 
@@ -1288,31 +1434,40 @@ static int lod_xattr_get(const struct lu_env *env, struct dt_object *dt,
        RETURN(rc);
 }
 
+/**
+ * Verify LVM EA.
+ *
+ * Checks that the magic of the stripe is sane.
+ *
+ * \param[in] lod      lod device
+ * \param[in] lum      a buffer storing LMV EA to verify
+ *
+ * \retval             0 if the EA is sane
+ * \retval             negative otherwise
+ */
 static int lod_verify_md_striping(struct lod_device *lod,
                                  const struct lmv_user_md_v1 *lum)
 {
-       int     rc = 0;
-       ENTRY;
-
-       if (unlikely(le32_to_cpu(lum->lum_magic) != LMV_USER_MAGIC))
-               GOTO(out, rc = -EINVAL);
-
-       if (unlikely(le32_to_cpu(lum->lum_stripe_count) == 0))
-               GOTO(out, rc = -EINVAL);
-out:
-       if (rc != 0)
+       if (unlikely(le32_to_cpu(lum->lum_magic) != LMV_USER_MAGIC)) {
                CERROR("%s: invalid lmv_user_md: magic = %x, "
                       "stripe_offset = %d, stripe_count = %u: rc = %d\n",
                       lod2obd(lod)->obd_name, le32_to_cpu(lum->lum_magic),
                       (int)le32_to_cpu(lum->lum_stripe_offset),
-                      le32_to_cpu(lum->lum_stripe_count), rc);
-       return rc;
+                      le32_to_cpu(lum->lum_stripe_count), -EINVAL);
+               return -EINVAL;
+       }
+
+       return 0;
 }
 
 /**
- * Master LMVEA will be same as slave LMVEA, except
- * 1. different magic
- * 2. lmv_master_mdt_index on slave LMV EA will be stripe_index.
+ * Initialize LMV EA for a slave.
+ *
+ * Initialize slave's LMV EA from the master's LMV EA.
+ *
+ * \param[in] master_lmv       a buffer containing master's EA
+ * \param[out] slave_lmv       a buffer where slave's EA will be stored
+ *
  */
 static void lod_prep_slave_lmv_md(struct lmv_mds_md_v1 *slave_lmv,
                                  const struct lmv_mds_md_v1 *master_lmv)
@@ -1321,8 +1476,21 @@ static void lod_prep_slave_lmv_md(struct lmv_mds_md_v1 *slave_lmv,
        slave_lmv->lmv_magic = cpu_to_le32(LMV_MAGIC_STRIPE);
 }
 
-int lod_prep_lmv_md(const struct lu_env *env, struct dt_object *dt,
-                   struct lu_buf *lmv_buf)
+/**
+ * Generate LMV EA.
+ *
+ * Generate LMV EA from the object passed as \a dt. The object must have
+ * the stripes created and initialized.
+ *
+ * \param[in] env      execution environment
+ * \param[in] dt       object
+ * \param[out] lmv_buf buffer storing generated LMV EA
+ *
+ * \retval             0 on success
+ * \retval             negative if failed
+ */
+static int lod_prep_lmv_md(const struct lu_env *env, struct dt_object *dt,
+                          struct lu_buf *lmv_buf)
 {
        struct lod_thread_info  *info = lod_env_info(env);
        struct lod_device       *lod = lu2lod_dev(dt->do_lu.lo_dev);
@@ -1358,11 +1526,25 @@ int lod_prep_lmv_md(const struct lu_env *env, struct dt_object *dt,
        lmm1->lmv_master_mdt_index = cpu_to_le32(mdtidx);
        lmv_buf->lb_buf = info->lti_ea_store;
        lmv_buf->lb_len = sizeof(*lmm1);
-       lo->ldo_dir_striping_cached = 1;
 
        RETURN(rc);
 }
 
+/**
+ * Create in-core represenation for a striped directory.
+ *
+ * Parse the buffer containing LMV EA and instantiate LU objects
+ * representing the stripe objects. The pointers to the objects are
+ * stored in ldo_stripe field of \a lo. This function is used when
+ * we need to access an already created object (i.e. load from a disk).
+ *
+ * \param[in] env      execution environment
+ * \param[in] lo       lod object
+ * \param[in] buf      buffer containing LMV EA
+ *
+ * \retval             0 on success
+ * \retval             negative if failed
+ */
 int lod_parse_dir_striping(const struct lu_env *env, struct lod_object *lo,
                           const struct lu_buf *buf)
 {
@@ -1440,95 +1622,244 @@ out:
        RETURN(rc);
 }
 
-static int lod_prep_md_striped_create(const struct lu_env *env,
-                                     struct dt_object *dt,
-                                     struct lu_attr *attr,
-                                     const struct lmv_user_md_v1 *lum,
-                                     struct dt_object_format *dof,
-                                     struct thandle *th)
+/**
+ * Declare create a striped directory.
+ *
+ * Declare creating a striped directory with a given stripe pattern on the
+ * specified MDTs. A striped directory is represented as a regular directory
+ * - an index listing all the stripes. The stripes point back to the master
+ * object with ".." and LinkEA. The master object gets LMV EA which
+ * identifies it as a striped directory. The function allocates FIDs
+ * for all stripes.
+ *
+ * \param[in] env      execution environment
+ * \param[in] dt       object
+ * \param[in] attr     attributes to initialize the objects with
+ * \param[in] dof      type of objects to be created
+ * \param[in] th       transaction handle
+ *
+ * \retval             0 on success
+ * \retval             negative if failed
+ */
+static int lod_dir_declare_create_stripes(const struct lu_env *env,
+                                         struct dt_object *dt,
+                                         struct lu_attr *attr,
+                                         struct dt_object_format *dof,
+                                         struct thandle *th)
 {
-       struct lod_device       *lod = lu2lod_dev(dt->do_lu.lo_dev);
-       struct lod_tgt_descs    *ltd = &lod->lod_mdt_descs;
-       struct lod_object       *lo = lod_dt_obj(dt);
        struct lod_thread_info  *info = lod_env_info(env);
-       struct dt_object        **stripe;
        struct lu_buf           lmv_buf;
        struct lu_buf           slave_lmv_buf;
        struct lmv_mds_md_v1    *lmm;
        struct lmv_mds_md_v1    *slave_lmm = NULL;
        struct dt_insert_rec    *rec = &info->lti_dt_rec;
-       __u32                   stripe_count;
-       int                     *idx_array;
-       int                     rc = 0;
+       struct lod_object       *lo = lod_dt_obj(dt);
+       int                     rc;
        __u32                   i;
-       __u32                   j;
        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_stripe_count) > 0);
+       rc = lod_prep_lmv_md(env, dt, &lmv_buf);
+       if (rc != 0)
+               GOTO(out, rc);
+       lmm = lmv_buf.lb_buf;
 
-       stripe_count = le32_to_cpu(lum->lum_stripe_count);
+       OBD_ALLOC_PTR(slave_lmm);
+       if (slave_lmm == NULL)
+               GOTO(out, rc = -ENOMEM);
 
-       /* shrink the stripe_count to the avaible MDT count */
-       if (stripe_count > lod->lod_remote_mdt_count + 1)
-               stripe_count = lod->lod_remote_mdt_count + 1;
+       lod_prep_slave_lmv_md(slave_lmm, lmm);
+       slave_lmv_buf.lb_buf = slave_lmm;
+       slave_lmv_buf.lb_len = sizeof(*slave_lmm);
 
-       OBD_ALLOC(stripe, sizeof(stripe[0]) * stripe_count);
-       if (stripe == NULL)
-               RETURN(-ENOMEM);
+       if (!dt_try_as_dir(env, dt_object_child(dt)))
+               GOTO(out, rc = -EINVAL);
 
-       OBD_ALLOC(idx_array, sizeof(idx_array[0]) * stripe_count);
-       if (idx_array == NULL)
-               GOTO(out_free, rc = -ENOMEM);
+       rec->rec_type = S_IFDIR;
+       for (i = 0; i < lo->ldo_stripenr; i++) {
+               struct dt_object        *dto = lo->ldo_stripe[i];
+               char                    *stripe_name = info->lti_key;
+               struct lu_name          *sname;
+               struct linkea_data       ldata          = { NULL };
+               struct lu_buf           linkea_buf;
 
-       for (i = 0; i < stripe_count; i++) {
-               struct lod_tgt_desc     *tgt = NULL;
-               struct dt_object        *dto;
-               struct lu_fid           fid = { 0 };
-               int                     idx;
-               struct lu_object_conf   conf = { 0 };
-               struct dt_device        *tgt_dt = NULL;
+               rc = lod_sub_object_declare_create(env, dto, attr, NULL,
+                                                  dof, th);
+               if (rc != 0)
+                       GOTO(out, rc);
 
-               if (i == 0) {
-                       /* Right now, master stripe and master object are
-                        * on the same MDT */
-                       idx = le32_to_cpu(lum->lum_stripe_offset);
-                       rc = obd_fid_alloc(env, lod->lod_child_exp, &fid,
-                                          NULL);
-                       if (rc < 0)
-                               GOTO(out_put, rc);
-                       tgt_dt = lod->lod_child;
-                       goto next;
-               }
+               if (!dt_try_as_dir(env, dto))
+                       GOTO(out, rc = -EINVAL);
 
-               idx = (idx_array[i - 1] + 1) % (lod->lod_remote_mdt_count + 1);
+               rc = lod_sub_object_declare_ref_add(env, dto, th);
+               if (rc != 0)
+                       GOTO(out, rc);
 
-               for (j = 0; j < lod->lod_remote_mdt_count;
-                    j++, idx = (idx + 1) % (lod->lod_remote_mdt_count + 1)) {
-                       bool already_allocated = false;
-                       __u32 k;
+               rec->rec_fid = lu_object_fid(&dto->do_lu);
+               rc = lod_sub_object_declare_insert(env, dto,
+                                       (const struct dt_rec *)rec,
+                                       (const struct dt_key *)dot, th);
+               if (rc != 0)
+                       GOTO(out, rc);
 
-                       CDEBUG(D_INFO, "try idx %d, mdt cnt %u,"
-                              " allocated %u, last allocated %d\n", idx,
-                              lod->lod_remote_mdt_count, i, idx_array[i - 1]);
+               /* master stripe FID will be put to .. */
+               rec->rec_fid = lu_object_fid(&dt->do_lu);
+               rc = lod_sub_object_declare_insert(env, dto,
+                                       (const struct dt_rec *)rec,
+                                       (const struct dt_key *)dotdot,
+                                       th);
+               if (rc != 0)
+                       GOTO(out, rc);
 
-                       /* Find next available target */
-                       if (!cfs_bitmap_check(ltd->ltd_tgt_bitmap, idx))
-                               continue;
+               if (!OBD_FAIL_CHECK(OBD_FAIL_LFSCK_LOST_SLAVE_LMV) ||
+                   cfs_fail_val != i) {
+                       if (OBD_FAIL_CHECK(OBD_FAIL_LFSCK_BAD_SLAVE_LMV) &&
+                           cfs_fail_val == i)
+                               slave_lmm->lmv_master_mdt_index =
+                                                       cpu_to_le32(i + 1);
+                       else
+                               slave_lmm->lmv_master_mdt_index =
+                                                       cpu_to_le32(i);
+                       rc = lod_sub_object_declare_xattr_set(env, dto,
+                                       &slave_lmv_buf, XATTR_NAME_LMV, 0, th);
+                       if (rc != 0)
+                               GOTO(out, rc);
+               }
 
-                       /* check whether the idx already exists
-                        * in current allocated array */
-                       for (k = 0; k < i; k++) {
-                               if (idx_array[k] == idx) {
-                                       already_allocated = true;
-                                       break;
-                               }
+               if (OBD_FAIL_CHECK(OBD_FAIL_LFSCK_BAD_SLAVE_NAME) &&
+                   cfs_fail_val == i)
+                       snprintf(stripe_name, sizeof(info->lti_key), DFID":%u",
+                               PFID(lu_object_fid(&dto->do_lu)), i + 1);
+               else
+                       snprintf(stripe_name, sizeof(info->lti_key), DFID":%u",
+                               PFID(lu_object_fid(&dto->do_lu)), i);
+
+               sname = lod_name_get(env, stripe_name, strlen(stripe_name));
+               rc = linkea_data_new(&ldata, &info->lti_linkea_buf);
+               if (rc != 0)
+                       GOTO(out, rc);
+
+               rc = linkea_add_buf(&ldata, sname, lu_object_fid(&dt->do_lu));
+               if (rc != 0)
+                       GOTO(out, rc);
+
+               linkea_buf.lb_buf = ldata.ld_buf->lb_buf;
+               linkea_buf.lb_len = ldata.ld_leh->leh_len;
+               rc = lod_sub_object_declare_xattr_set(env, dto, &linkea_buf,
+                                         XATTR_NAME_LINK, 0, th);
+               if (rc != 0)
+                       GOTO(out, rc);
+
+               rec->rec_fid = lu_object_fid(&dto->do_lu);
+               rc = lod_sub_object_declare_insert(env, dt_object_child(dt),
+                                      (const struct dt_rec *)rec,
+                                      (const struct dt_key *)stripe_name,
+                                      th);
+               if (rc != 0)
+                       GOTO(out, rc);
+
+               rc = lod_sub_object_declare_ref_add(env, dt_object_child(dt),
+                                                   th);
+               if (rc != 0)
+                       GOTO(out, rc);
+       }
+
+       rc = lod_sub_object_declare_xattr_set(env, dt_object_child(dt),
+                               &lmv_buf, XATTR_NAME_LMV, 0, th);
+       if (rc != 0)
+               GOTO(out, rc);
+out:
+       if (slave_lmm != NULL)
+               OBD_FREE_PTR(slave_lmm);
+
+       RETURN(rc);
+}
+
+static int lod_prep_md_striped_create(const struct lu_env *env,
+                                     struct dt_object *dt,
+                                     struct lu_attr *attr,
+                                     const struct lmv_user_md_v1 *lum,
+                                     struct dt_object_format *dof,
+                                     struct thandle *th)
+{
+       struct lod_device       *lod = lu2lod_dev(dt->do_lu.lo_dev);
+       struct lod_tgt_descs    *ltd = &lod->lod_mdt_descs;
+       struct lod_object       *lo = lod_dt_obj(dt);
+       struct dt_object        **stripe;
+       __u32                   stripe_count;
+       int                     *idx_array;
+       __u32                   master_index;
+       int                     rc = 0;
+       __u32                   i;
+       __u32                   j;
+       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_stripe_count) > 0);
+
+       stripe_count = le32_to_cpu(lum->lum_stripe_count);
+
+       /* shrink the stripe_count to the avaible MDT count */
+       if (stripe_count > lod->lod_remote_mdt_count + 1 &&
+           !OBD_FAIL_CHECK(OBD_FAIL_LARGE_STRIPE))
+               stripe_count = lod->lod_remote_mdt_count + 1;
+
+       OBD_ALLOC(stripe, sizeof(stripe[0]) * stripe_count);
+       if (stripe == NULL)
+               RETURN(-ENOMEM);
+
+       OBD_ALLOC(idx_array, sizeof(idx_array[0]) * stripe_count);
+       if (idx_array == NULL)
+               GOTO(out_free, rc = -ENOMEM);
+
+       /* Start index will be the master MDT */
+       master_index = lu_site2seq(lod2lu_dev(lod)->ld_site)->ss_node_id;
+       idx_array[0] = master_index;
+       for (i = 0; i < stripe_count; i++) {
+               struct lod_tgt_desc     *tgt = NULL;
+               struct dt_object        *dto;
+               struct lu_fid           fid = { 0 };
+               int                     idx;
+               struct lu_object_conf   conf = { 0 };
+               struct dt_device        *tgt_dt = NULL;
+
+               /* Try to find next avaible target */
+               idx = idx_array[i];
+               for (j = 0; j < lod->lod_remote_mdt_count;
+                    j++, idx = (idx + 1) % (lod->lod_remote_mdt_count + 1)) {
+                       bool already_allocated = false;
+                       __u32 k;
+
+                       CDEBUG(D_INFO, "try idx %d, mdt cnt %u, allocated %u\n",
+                              idx, lod->lod_remote_mdt_count + 1, i);
+                       if (idx == master_index) {
+                               /* Allocate the FID locally */
+                               rc = obd_fid_alloc(env, lod->lod_child_exp,
+                                                  &fid, NULL);
+                               if (rc < 0)
+                                       GOTO(out_put, rc);
+                               tgt_dt = lod->lod_child;
+                               break;
                        }
 
-                       if (already_allocated)
+                       /* Find next available target */
+                       if (!cfs_bitmap_check(ltd->ltd_tgt_bitmap, idx))
                                continue;
 
+                       if (likely(!OBD_FAIL_CHECK(OBD_FAIL_LARGE_STRIPE))) {
+                               /* check whether the idx already exists
+                                * in current allocated array */
+                               for (k = 0; k < i; k++) {
+                                       if (idx_array[k] == idx) {
+                                               already_allocated = true;
+                                               break;
+                                       }
+                               }
+
+                               if (already_allocated)
+                                       continue;
+                       }
+
                        /* check the status of the OSP */
                        tgt = LTD_TGT(ltd, idx);
                        if (tgt == NULL)
@@ -1558,11 +1889,13 @@ static int lod_prep_md_striped_create(const struct lu_env *env,
                        break;
                }
 
-               CDEBUG(D_INFO, "idx %d, mdt cnt %u,"
-                      " allocated %u, last allocated %d\n", idx,
-                      lod->lod_remote_mdt_count, i, idx_array[i - 1]);
-
-next:
+               CDEBUG(D_INFO, "Get idx %d, for stripe %d "DFID"\n",
+                      idx, i, PFID(&fid));
+               idx_array[i] = idx;
+               /* Set the start index for next stripe allocation */
+               if (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
                 * in the above loop */
                LASSERT(tgt_dt != NULL);
@@ -1574,7 +1907,6 @@ next:
                if (IS_ERR(dto))
                        GOTO(out_put, rc = PTR_ERR(dto));
                stripe[i] = dto;
-               idx_array[i] = idx;
        }
 
        lo->ldo_dir_striped = 1;
@@ -1585,126 +1917,7 @@ next:
        if (lo->ldo_stripenr == 0)
                GOTO(out_put, rc = -ENOSPC);
 
-       rc = lod_prep_lmv_md(env, dt, &lmv_buf);
-       if (rc != 0)
-               GOTO(out_put, rc);
-       lmm = lmv_buf.lb_buf;
-
-       OBD_ALLOC_PTR(slave_lmm);
-       if (slave_lmm == NULL)
-               GOTO(out_put, rc = -ENOMEM);
-
-       lod_prep_slave_lmv_md(slave_lmm, lmm);
-       slave_lmv_buf.lb_buf = slave_lmm;
-       slave_lmv_buf.lb_len = sizeof(*slave_lmm);
-
-       if (!dt_try_as_dir(env, dt_object_child(dt)))
-               GOTO(out_put, rc = -EINVAL);
-
-       rec->rec_type = S_IFDIR;
-       for (i = 0; i < lo->ldo_stripenr; i++) {
-               struct dt_object        *dto            = stripe[i];
-               char                    *stripe_name    = info->lti_key;
-               struct lu_name          *sname;
-               struct linkea_data       ldata          = { 0 };
-               struct lu_buf            linkea_buf;
-
-               rc = dt_declare_create(env, dto, attr, NULL, dof, th);
-               if (rc != 0)
-                       GOTO(out_put, rc);
-
-               if (!dt_try_as_dir(env, dto))
-                       GOTO(out_put, rc = -EINVAL);
-
-               rec->rec_fid = lu_object_fid(&dto->do_lu);
-               rc = dt_declare_insert(env, dto, (const struct dt_rec *)rec,
-                                      (const struct dt_key *)dot, th);
-               if (rc != 0)
-                       GOTO(out_put, rc);
-
-               /* master stripe FID will be put to .. */
-               rec->rec_fid = lu_object_fid(&dt->do_lu);
-               rc = dt_declare_insert(env, dto, (const struct dt_rec *)rec,
-                                      (const struct dt_key *)dotdot, th);
-               if (rc != 0)
-                       GOTO(out_put, rc);
-
-               /* probably nothing to inherite */
-               if (lo->ldo_striping_cached &&
-                   !LOVEA_DELETE_VALUES(lo->ldo_def_stripe_size,
-                                        lo->ldo_def_stripenr,
-                                        lo->ldo_def_stripe_offset)) {
-                       struct lov_user_md_v3   *v3;
-
-                       /* sigh, lti_ea_store has been used for lmv_buf,
-                        * so we have to allocate buffer for default
-                        * stripe EA */
-                       OBD_ALLOC_PTR(v3);
-                       if (v3 == NULL)
-                               GOTO(out_put, rc = -ENOMEM);
-
-                       memset(v3, 0, sizeof(*v3));
-                       v3->lmm_magic = cpu_to_le32(LOV_USER_MAGIC_V3);
-                       v3->lmm_stripe_count =
-                               cpu_to_le16(lo->ldo_def_stripenr);
-                       v3->lmm_stripe_offset =
-                               cpu_to_le16(lo->ldo_def_stripe_offset);
-                       v3->lmm_stripe_size =
-                               cpu_to_le32(lo->ldo_def_stripe_size);
-                       if (lo->ldo_pool != NULL)
-                               strlcpy(v3->lmm_pool_name, lo->ldo_pool,
-                                       sizeof(v3->lmm_pool_name));
-
-                       info->lti_buf.lb_buf = v3;
-                       info->lti_buf.lb_len = sizeof(*v3);
-                       rc = dt_declare_xattr_set(env, dto,
-                                                 &info->lti_buf,
-                                                 XATTR_NAME_LOV,
-                                                 0, th);
-                       OBD_FREE_PTR(v3);
-                       if (rc != 0)
-                               GOTO(out_put, rc);
-               }
-
-               slave_lmm->lmv_master_mdt_index = cpu_to_le32(i);
-               rc = dt_declare_xattr_set(env, dto, &slave_lmv_buf,
-                                         XATTR_NAME_LMV, 0, th);
-               if (rc != 0)
-                       GOTO(out_put, rc);
-
-               snprintf(stripe_name, sizeof(info->lti_key), DFID":%u",
-                       PFID(lu_object_fid(&dto->do_lu)), i);
-
-               sname = lod_name_get(env, stripe_name, strlen(stripe_name));
-               rc = linkea_data_new(&ldata, &info->lti_linkea_buf);
-               if (rc != 0)
-                       GOTO(out_put, rc);
-
-               rc = linkea_add_buf(&ldata, sname, lu_object_fid(&dt->do_lu));
-               if (rc != 0)
-                       GOTO(out_put, rc);
-
-               linkea_buf.lb_buf = ldata.ld_buf->lb_buf;
-               linkea_buf.lb_len = ldata.ld_leh->leh_len;
-               rc = dt_declare_xattr_set(env, dto, &linkea_buf,
-                                         XATTR_NAME_LINK, 0, th);
-               if (rc != 0)
-                       GOTO(out_put, rc);
-
-               rec->rec_fid = lu_object_fid(&dto->do_lu);
-               rc = dt_declare_insert(env, dt_object_child(dt),
-                                      (const struct dt_rec *)rec,
-                                      (const struct dt_key *)stripe_name, th);
-               if (rc != 0)
-                       GOTO(out_put, rc);
-
-               rc = dt_declare_ref_add(env, dt_object_child(dt), th);
-               if (rc != 0)
-                       GOTO(out_put, rc);
-       }
-
-       rc = dt_declare_xattr_set(env, dt_object_child(dt), &lmv_buf,
-                                 XATTR_NAME_LMV, 0, th);
+       rc = lod_dir_declare_create_stripes(env, dt, attr, dof, th);
        if (rc != 0)
                GOTO(out_put, rc);
 
@@ -1722,14 +1935,28 @@ out_put:
 out_free:
        if (idx_array != NULL)
                OBD_FREE(idx_array, sizeof(idx_array[0]) * stripe_count);
-       if (slave_lmm != NULL)
-               OBD_FREE_PTR(slave_lmm);
 
        RETURN(rc);
 }
 
 /**
  * Declare create striped md object.
+ *
+ * The function declares intention to create a striped directory. This is a
+ * wrapper for lod_prep_md_striped_create(). The only additional functionality
+ * is to verify pattern \a lum_buf is good. Check that function for the details.
+ *
+ * \param[in] env      execution environment
+ * \param[in] dt       object
+ * \param[in] attr     attributes to initialize the objects with
+ * \param[in] lum_buf  a pattern specifying the number of stripes and
+ *                     MDT to start from
+ * \param[in] dof      type of objects to be created
+ * \param[in] th       transaction handle
+ *
+ * \retval             0 on success
+ * \retval             negative if failed
+ *
  */
 static int lod_declare_xattr_set_lmv(const struct lu_env *env,
                                     struct dt_object *dt,
@@ -1770,6 +1997,17 @@ out:
        RETURN(rc);
 }
 
+
+/**
+ * Implementation of dt_object_operations::do_declare_xattr_set.
+ *
+ * Used with regular (non-striped) objects. Basically it
+ * initializes the striping information and applies the
+ * change to all the stripes.
+ *
+ * \see dt_object_operations::do_declare_xattr_set() in the API description
+ * for details.
+ */
 static int lod_dir_declare_xattr_set(const struct lu_env *env,
                                     struct dt_object *dt,
                                     const struct lu_buf *buf,
@@ -1793,26 +2031,30 @@ static int lod_dir_declare_xattr_set(const struct lu_env *env,
                        RETURN(rc);
        }
 
-       rc = dt_declare_xattr_set(env, next, buf, name, fl, th);
+       rc = lod_sub_object_declare_xattr_set(env, next, buf, name, fl, th);
        if (rc != 0)
                RETURN(rc);
 
+       /* Note: Do not set LinkEA on sub-stripes, otherwise
+        * it will confuse the fid2path process(see mdt_path_current()).
+        * The linkEA between master and sub-stripes is set in
+        * lod_xattr_set_lmv(). */
+       if (strcmp(name, XATTR_NAME_LINK) == 0)
+               RETURN(0);
+
        /* set xattr to each stripes, if needed */
        rc = lod_load_striping(env, lo);
        if (rc != 0)
                RETURN(rc);
 
-       /* Note: Do not set LinkEA on sub-stripes, otherwise
-        * it will confuse the fid2path process(see mdt_path_current()).
-        * The linkEA between master and sub-stripes is set in
-        * lod_xattr_set_lmv(). */
-       if (lo->ldo_stripenr == 0 || strcmp(name, XATTR_NAME_LINK) == 0)
+       if (lo->ldo_stripenr == 0)
                RETURN(0);
 
        for (i = 0; i < lo->ldo_stripenr; i++) {
                LASSERT(lo->ldo_stripe[i]);
-               rc = dt_declare_xattr_set(env, lo->ldo_stripe[i], buf,
-                                         name, fl, th);
+
+               rc = lod_sub_object_declare_xattr_set(env, lo->ldo_stripe[i],
+                                               buf, name, fl, th);
                if (rc != 0)
                        break;
        }
@@ -1820,15 +2062,94 @@ static int lod_dir_declare_xattr_set(const struct lu_env *env,
        RETURN(rc);
 }
 
-/*
- * LOV xattr is a storage for striping, and LOD owns this xattr.
- * but LOD allows others to control striping to some extent
- * - to reset strping
- * - to set new defined striping
- * - to set new semi-defined striping
- *   - number of stripes is defined
- *   - number of stripes + osts are defined
- *   - ??
+/**
+ * Reset parent FID on OST object
+ *
+ * Replace parent FID with @dt object FID, which is only called during migration
+ * to reset the parent FID after the MDT object is migrated to the new MDT, i.e.
+ * the FID is changed.
+ *
+ * \param[in] env execution environment
+ * \param[in] dt dt_object whose stripes's parent FID will be reset
+ * \parem[in] th thandle
+ * \param[in] declare if it is declare
+ *
+ * \retval     0 if reset succeeds
+ * \retval     negative errno if reset fais
+ */
+static int lod_object_replace_parent_fid(const struct lu_env *env,
+                                        struct dt_object *dt,
+                                        struct thandle *th, bool declare)
+{
+       struct lod_object *lo = lod_dt_obj(dt);
+       struct lod_thread_info  *info = lod_env_info(env);
+       struct lu_buf *buf = &info->lti_buf;
+       struct filter_fid *ff;
+       int i, rc;
+       ENTRY;
+
+       LASSERT(S_ISREG(dt->do_lu.lo_header->loh_attr));
+
+       /* set xattr to each stripes, if needed */
+       rc = lod_load_striping(env, lo);
+       if (rc != 0)
+               RETURN(rc);
+
+       if (lo->ldo_stripenr == 0)
+               RETURN(0);
+
+       if (info->lti_ea_store_size < sizeof(*ff)) {
+               rc = lod_ea_store_resize(info, sizeof(*ff));
+               if (rc != 0)
+                       RETURN(rc);
+       }
+
+       buf->lb_buf = info->lti_ea_store;
+       buf->lb_len = info->lti_ea_store_size;
+
+       for (i = 0; i < lo->ldo_stripenr; i++) {
+               if (lo->ldo_stripe[i] == NULL)
+                       continue;
+
+               rc = dt_xattr_get(env, lo->ldo_stripe[i], buf,
+                                 XATTR_NAME_FID);
+               if (rc < 0) {
+                       rc = 0;
+                       continue;
+               }
+
+               ff = buf->lb_buf;
+               fid_le_to_cpu(&ff->ff_parent, &ff->ff_parent);
+               ff->ff_parent.f_seq = lu_object_fid(&dt->do_lu)->f_seq;
+               ff->ff_parent.f_oid = lu_object_fid(&dt->do_lu)->f_oid;
+               fid_cpu_to_le(&ff->ff_parent, &ff->ff_parent);
+
+               if (declare) {
+                       rc = lod_sub_object_declare_xattr_set(env,
+                                               lo->ldo_stripe[i], buf,
+                                               XATTR_NAME_FID,
+                                               LU_XATTR_REPLACE, th);
+               } else {
+                       rc = lod_sub_object_xattr_set(env, lo->ldo_stripe[i],
+                                                     buf, XATTR_NAME_FID,
+                                                     LU_XATTR_REPLACE, th);
+               }
+               if (rc < 0)
+                       break;
+       }
+
+       RETURN(rc);
+}
+
+/**
+ * Implementation of dt_object_operations::do_declare_xattr_set.
+ *
+ * \see dt_object_operations::do_declare_xattr_set() in the API description
+ * for details.
+ *
+ * the extension to the API:
+ *   - declaring LOVEA requests striping creation
+ *   - LU_XATTR_REPLACE means layout swap
  */
 static int lod_declare_xattr_set(const struct lu_env *env,
                                 struct dt_object *dt,
@@ -1855,7 +2176,7 @@ static int lod_declare_xattr_set(const struct lu_env *env,
                 * this is a request to manipulate object's striping
                 */
                if (dt_object_exists(dt)) {
-                       rc = dt_attr_get(env, next, attr, BYPASS_CAPA);
+                       rc = dt_attr_get(env, next, attr);
                        if (rc)
                                RETURN(rc);
                } else {
@@ -1866,29 +2187,52 @@ static int lod_declare_xattr_set(const struct lu_env *env,
                rc = lod_declare_striped_object(env, dt, attr, buf, th);
        } else if (S_ISDIR(mode)) {
                rc = lod_dir_declare_xattr_set(env, dt, buf, name, fl, th);
+       } else if (strcmp(name, XATTR_NAME_FID) == 0) {
+               rc = lod_object_replace_parent_fid(env, dt, th, true);
        } else {
-               rc = dt_declare_xattr_set(env, next, buf, name, fl, th);
+               rc = lod_sub_object_declare_xattr_set(env, next, buf, name,
+                                                     fl, th);
        }
 
        RETURN(rc);
 }
 
+/**
+ * Resets cached default striping in the object.
+ *
+ * \param[in] lo       object
+ */
 static void lod_lov_stripe_cache_clear(struct lod_object *lo)
 {
-       lo->ldo_striping_cached = 0;
        lo->ldo_def_striping_set = 0;
+       lo->ldo_def_striping_cached = 0;
        lod_object_set_pool(lo, NULL);
        lo->ldo_def_stripe_size = 0;
        lo->ldo_def_stripenr = 0;
        if (lo->ldo_dir_stripe != NULL)
-               lo->ldo_dir_striping_cached = 0;
+               lo->ldo_dir_def_striping_cached = 0;
 }
 
+/**
+ * Apply xattr changes to the object.
+ *
+ * Applies xattr changes to the object and the stripes if the latter exist.
+ *
+ * \param[in] env      execution environment
+ * \param[in] dt       object
+ * \param[in] buf      buffer pointing to the new value of xattr
+ * \param[in] name     name of xattr
+ * \param[in] fl       flags
+ * \param[in] th       transaction handle
+ *
+ * \retval             0 on success
+ * \retval             negative if failed
+ */
 static int lod_xattr_set_internal(const struct lu_env *env,
                                  struct dt_object *dt,
                                  const struct lu_buf *buf,
-                                 const char *name, int fl, struct thandle *th,
-                                 struct lustre_capa *capa)
+                                 const char *name, int fl,
+                                 struct thandle *th)
 {
        struct dt_object        *next = dt_object_child(dt);
        struct lod_object       *lo = lod_dt_obj(dt);
@@ -1896,7 +2240,7 @@ static int lod_xattr_set_internal(const struct lu_env *env,
        int                     i;
        ENTRY;
 
-       rc = dt_xattr_set(env, next, buf, name, fl, th, capa);
+       rc = lod_sub_object_xattr_set(env, next, buf, name, fl, th);
        if (rc != 0 || !S_ISDIR(dt->do_lu.lo_header->loh_attr))
                RETURN(rc);
 
@@ -1909,8 +2253,9 @@ static int lod_xattr_set_internal(const struct lu_env *env,
 
        for (i = 0; i < lo->ldo_stripenr; i++) {
                LASSERT(lo->ldo_stripe[i]);
-               rc = dt_xattr_set(env, lo->ldo_stripe[i], buf, name, fl, th,
-                                 capa);
+
+               rc = lod_sub_object_xattr_set(env, lo->ldo_stripe[i], buf, name,
+                                             fl, th);
                if (rc != 0)
                        break;
        }
@@ -1918,10 +2263,22 @@ static int lod_xattr_set_internal(const struct lu_env *env,
        RETURN(rc);
 }
 
+/**
+ * Delete an extended attribute.
+ *
+ * Deletes specified xattr from the object and the stripes if the latter exist.
+ *
+ * \param[in] env      execution environment
+ * \param[in] dt       object
+ * \param[in] name     name of xattr
+ * \param[in] th       transaction handle
+ *
+ * \retval             0 on success
+ * \retval             negative if failed
+ */
 static int lod_xattr_del_internal(const struct lu_env *env,
                                  struct dt_object *dt,
-                                 const char *name, struct thandle *th,
-                                 struct lustre_capa *capa)
+                                 const char *name, struct thandle *th)
 {
        struct dt_object        *next = dt_object_child(dt);
        struct lod_object       *lo = lod_dt_obj(dt);
@@ -1929,7 +2286,7 @@ static int lod_xattr_del_internal(const struct lu_env *env,
        int                     i;
        ENTRY;
 
-       rc = dt_xattr_del(env, next, name, th, capa);
+       rc = lod_sub_object_xattr_del(env, next, name, th);
        if (rc != 0 || !S_ISDIR(dt->do_lu.lo_header->loh_attr))
                RETURN(rc);
 
@@ -1938,8 +2295,9 @@ static int lod_xattr_del_internal(const struct lu_env *env,
 
        for (i = 0; i < lo->ldo_stripenr; i++) {
                LASSERT(lo->ldo_stripe[i]);
-               rc = dt_xattr_del(env, lo->ldo_stripe[i], name, th,
-                                 capa);
+
+               rc = lod_sub_object_xattr_del(env, lo->ldo_stripe[i], name,
+                                             th);
                if (rc != 0)
                        break;
        }
@@ -1947,17 +2305,35 @@ static int lod_xattr_del_internal(const struct lu_env *env,
        RETURN(rc);
 }
 
+/**
+ * Set default striping on a directory.
+ *
+ * Sets specified striping on a directory object unless it matches the default
+ * striping (LOVEA_DELETE_VALUES() macro). In the latter case remove existing
+ * EA. This striping will be used when regular file is being created in this
+ * directory.
+ *
+ * \param[in] env      execution environment
+ * \param[in] dt       the striped object
+ * \param[in] buf      buffer with the striping
+ * \param[in] name     name of EA
+ * \param[in] fl       xattr flag (see OSD API description)
+ * \param[in] th       transaction handle
+ *
+ * \retval             0 on success
+ * \retval             negative if failed
+ */
 static int lod_xattr_set_lov_on_dir(const struct lu_env *env,
                                    struct dt_object *dt,
                                    const struct lu_buf *buf,
                                    const char *name, int fl,
-                                   struct thandle *th,
-                                   struct lustre_capa *capa)
+                                   struct thandle *th)
 {
        struct lod_device       *d = lu2lod_dev(dt->do_lu.lo_dev);
        struct lod_object       *l = lod_dt_obj(dt);
        struct lov_user_md_v1   *lum;
        struct lov_user_md_v3   *v3 = NULL;
+       const char              *pool_name = NULL;
        int                      rc;
        ENTRY;
 
@@ -1973,8 +2349,11 @@ static int lod_xattr_set_lov_on_dir(const struct lu_env *env,
        if (rc)
                RETURN(rc);
 
-       if (lum->lmm_magic == LOV_USER_MAGIC_V3)
+       if (lum->lmm_magic == LOV_USER_MAGIC_V3) {
                v3 = buf->lb_buf;
+               if (v3->lmm_pool_name[0] != '\0')
+                       pool_name = v3->lmm_pool_name;
+       }
 
        /* if { size, offset, count } = { 0, -1, 0 } and no pool
         * (i.e. all default values specified) then delete default
@@ -1986,26 +2365,41 @@ static int lod_xattr_set_lov_on_dir(const struct lu_env *env,
                (int)lum->lmm_stripe_offset,
                v3 ? "from" : "", v3 ? v3->lmm_pool_name : "");
 
-       if (LOVEA_DELETE_VALUES((lum->lmm_stripe_size),
-                               (lum->lmm_stripe_count),
-                               (lum->lmm_stripe_offset)) &&
-                       lum->lmm_magic == LOV_USER_MAGIC_V1) {
-               rc = lod_xattr_del_internal(env, dt, name, th, capa);
+       if (LOVEA_DELETE_VALUES(lum->lmm_stripe_size, lum->lmm_stripe_count,
+                               lum->lmm_stripe_offset, pool_name)) {
+               rc = lod_xattr_del_internal(env, dt, name, th);
                if (rc == -ENODATA)
                        rc = 0;
        } else {
-               rc = lod_xattr_set_internal(env, dt, buf, name, fl, th, capa);
+               rc = lod_xattr_set_internal(env, dt, buf, name, fl, th);
        }
 
        RETURN(rc);
 }
 
+/**
+ * Set default striping on a directory object.
+ *
+ * Sets specified striping on a directory object unless it matches the default
+ * striping (LOVEA_DELETE_VALUES() macro). In the latter case remove existing
+ * EA. This striping will be used when a new directory is being created in the
+ * directory.
+ *
+ * \param[in] env      execution environment
+ * \param[in] dt       the striped object
+ * \param[in] buf      buffer with the striping
+ * \param[in] name     name of EA
+ * \param[in] fl       xattr flag (see OSD API description)
+ * \param[in] th       transaction handle
+ *
+ * \retval             0 on success
+ * \retval             negative if failed
+ */
 static int lod_xattr_set_default_lmv_on_dir(const struct lu_env *env,
                                            struct dt_object *dt,
                                            const struct lu_buf *buf,
                                            const char *name, int fl,
-                                           struct thandle *th,
-                                           struct lustre_capa *capa)
+                                           struct thandle *th)
 {
        struct lod_object       *l = lod_dt_obj(dt);
        struct lmv_user_md_v1   *lum;
@@ -2022,11 +2416,11 @@ 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) {
-               rc = lod_xattr_del_internal(env, dt, name, th, capa);
+               rc = lod_xattr_del_internal(env, dt, name, th);
                if (rc == -ENODATA)
                        rc = 0;
        } else {
-               rc = lod_xattr_set_internal(env, dt, buf, name, fl, th, capa);
+               rc = lod_xattr_set_internal(env, dt, buf, name, fl, th);
                if (rc != 0)
                        RETURN(rc);
        }
@@ -2038,17 +2432,32 @@ static int lod_xattr_set_default_lmv_on_dir(const struct lu_env *env,
                        RETURN(-ENOMEM);
        }
 
-       l->ldo_dir_striping_cached = 0;
-       l->ldo_dir_def_striping_set = 1;
-       l->ldo_dir_def_stripenr = le32_to_cpu(lum->lum_stripe_count);
-
+       l->ldo_dir_def_striping_cached = 0;
        RETURN(rc);
 }
 
+/**
+ * Turn directory into a striped directory.
+ *
+ * During replay the client sends the striping created before MDT
+ * failure, then the layer above LOD sends this defined striping
+ * using ->do_xattr_set(), so LOD uses this method to replay creation
+ * of the stripes. Notice the original information for the striping
+ * (#stripes, FIDs, etc) was transferred in declare path.
+ *
+ * \param[in] env      execution environment
+ * \param[in] dt       the striped object
+ * \param[in] buf      not used currently
+ * \param[in] name     not used currently
+ * \param[in] fl       xattr flag (see OSD API description)
+ * \param[in] th       transaction handle
+ *
+ * \retval             0 on success
+ * \retval             negative if failed
+ */
 static int lod_xattr_set_lmv(const struct lu_env *env, struct dt_object *dt,
                             const struct lu_buf *buf, const char *name,
-                            int fl, struct thandle *th,
-                            struct lustre_capa *capa)
+                            int fl, struct thandle *th)
 {
        struct lod_object       *lo = lod_dt_obj(dt);
        struct lod_thread_info  *info = lod_env_info(env);
@@ -2071,11 +2480,12 @@ static int lod_xattr_set_lmv(const struct lu_env *env, struct dt_object *dt,
        if (lo->ldo_stripenr == 0)
                RETURN(0);
 
-       rc = dt_attr_get(env, dt_object_child(dt), attr, BYPASS_CAPA);
+       rc = dt_attr_get(env, dt_object_child(dt), attr);
        if (rc != 0)
                RETURN(rc);
 
-       attr->la_valid = LA_TYPE | LA_MODE;
+       attr->la_valid = LA_ATIME | LA_MTIME | LA_CTIME |
+                        LA_MODE | LA_UID | LA_GID | LA_TYPE;
        dof->dof_type = DFT_DIR;
 
        rc = lod_prep_lmv_md(env, dt, &lmv_buf);
@@ -2093,73 +2503,63 @@ static int lod_xattr_set_lmv(const struct lu_env *env, struct dt_object *dt,
 
        rec->rec_type = S_IFDIR;
        for (i = 0; i < lo->ldo_stripenr; i++) {
-               struct dt_object        *dto;
-               char                    *stripe_name    = info->lti_key;
+               struct dt_object *dto;
+               char             *stripe_name = info->lti_key;
                struct lu_name          *sname;
-               struct linkea_data       ldata          = { 0 };
+               struct linkea_data       ldata          = { NULL };
                struct lu_buf            linkea_buf;
 
                dto = lo->ldo_stripe[i];
+
                dt_write_lock(env, dto, MOR_TGT_CHILD);
-               rc = dt_create(env, dto, attr, NULL, dof, th);
+               rc = lod_sub_object_create(env, dto, attr, NULL, dof,
+                                          th);
+               if (rc != 0) {
+                       dt_write_unlock(env, dto);
+                       GOTO(out, rc);
+               }
+
+               rc = lod_sub_object_ref_add(env, dto, th);
                dt_write_unlock(env, dto);
                if (rc != 0)
-                       RETURN(rc);
+                       GOTO(out, rc);
 
                rec->rec_fid = lu_object_fid(&dto->do_lu);
-               rc = dt_insert(env, dto, (const struct dt_rec *)rec,
-                              (const struct dt_key *)dot, th, capa, 0);
+               rc = lod_sub_object_index_insert(env, dto,
+                               (const struct dt_rec *)rec,
+                               (const struct dt_key *)dot, th, 0);
                if (rc != 0)
-                       RETURN(rc);
+                       GOTO(out, rc);
 
                rec->rec_fid = lu_object_fid(&dt->do_lu);
-               rc = dt_insert(env, dto, (struct dt_rec *)rec,
-                              (const struct dt_key *)dotdot, th, capa, 0);
+               rc = lod_sub_object_index_insert(env, dto, (struct dt_rec *)rec,
+                              (const struct dt_key *)dotdot, th, 0);
                if (rc != 0)
-                       RETURN(rc);
-
-               if (lo->ldo_striping_cached &&
-                   !LOVEA_DELETE_VALUES(lo->ldo_def_stripe_size,
-                                        lo->ldo_def_stripenr,
-                                        lo->ldo_def_stripe_offset)) {
-                       struct lov_user_md_v3   *v3;
-
-                       /* sigh, lti_ea_store has been used for lmv_buf,
-                        * so we have to allocate buffer for default
-                        * stripe EA */
-                       OBD_ALLOC_PTR(v3);
-                       if (v3 == NULL)
-                               GOTO(out, rc);
+                       GOTO(out, rc);
 
-                       memset(v3, 0, sizeof(*v3));
-                       v3->lmm_magic = cpu_to_le32(LOV_USER_MAGIC_V3);
-                       v3->lmm_stripe_count =
-                               cpu_to_le16(lo->ldo_def_stripenr);
-                       v3->lmm_stripe_offset =
-                               cpu_to_le16(lo->ldo_def_stripe_offset);
-                       v3->lmm_stripe_size =
-                               cpu_to_le32(lo->ldo_def_stripe_size);
-                       if (lo->ldo_pool != NULL)
-                               strlcpy(v3->lmm_pool_name, lo->ldo_pool,
-                                       sizeof(v3->lmm_pool_name));
-
-                       info->lti_buf.lb_buf = v3;
-                       info->lti_buf.lb_len = sizeof(*v3);
-                       rc = dt_xattr_set(env, dto, &info->lti_buf,
-                                         XATTR_NAME_LOV, 0, th, capa);
-                       OBD_FREE_PTR(v3);
+               if (!OBD_FAIL_CHECK(OBD_FAIL_LFSCK_LOST_SLAVE_LMV) ||
+                   cfs_fail_val != i) {
+                       if (OBD_FAIL_CHECK(OBD_FAIL_LFSCK_BAD_SLAVE_LMV) &&
+                           cfs_fail_val == i)
+                               slave_lmm->lmv_master_mdt_index =
+                                                       cpu_to_le32(i + 1);
+                       else
+                               slave_lmm->lmv_master_mdt_index =
+                                                       cpu_to_le32(i);
+
+                       rc = lod_sub_object_xattr_set(env, dto, &slave_lmv_buf,
+                                                     XATTR_NAME_LMV, fl, th);
                        if (rc != 0)
                                GOTO(out, rc);
                }
 
-               slave_lmm->lmv_master_mdt_index = cpu_to_le32(i);
-               rc = dt_xattr_set(env, dto, &slave_lmv_buf, XATTR_NAME_LMV,
-                                 fl, th, capa);
-               if (rc != 0)
-                       GOTO(out, rc);
-
-               snprintf(stripe_name, sizeof(info->lti_key), DFID":%d",
-                        PFID(lu_object_fid(&dto->do_lu)), i);
+               if (OBD_FAIL_CHECK(OBD_FAIL_LFSCK_BAD_SLAVE_NAME) &&
+                   cfs_fail_val == i)
+                       snprintf(stripe_name, sizeof(info->lti_key), DFID":%d",
+                                PFID(lu_object_fid(&dto->do_lu)), i + 1);
+               else
+                       snprintf(stripe_name, sizeof(info->lti_key), DFID":%d",
+                                PFID(lu_object_fid(&dto->do_lu)), i);
 
                sname = lod_name_get(env, stripe_name, strlen(stripe_name));
                rc = linkea_data_new(&ldata, &info->lti_linkea_buf);
@@ -2172,26 +2572,26 @@ static int lod_xattr_set_lmv(const struct lu_env *env, struct dt_object *dt,
 
                linkea_buf.lb_buf = ldata.ld_buf->lb_buf;
                linkea_buf.lb_len = ldata.ld_leh->leh_len;
-               rc = dt_xattr_set(env, dto, &linkea_buf, XATTR_NAME_LINK,
-                                 0, th, BYPASS_CAPA);
+               rc = lod_sub_object_xattr_set(env, dto, &linkea_buf,
+                                       XATTR_NAME_LINK, 0, th);
                if (rc != 0)
                        GOTO(out, rc);
 
                rec->rec_fid = lu_object_fid(&dto->do_lu);
-               rc = dt_insert(env, dt_object_child(dt),
+               rc = lod_sub_object_index_insert(env, dt_object_child(dt),
                               (const struct dt_rec *)rec,
-                              (const struct dt_key *)stripe_name, th, capa, 0);
+                              (const struct dt_key *)stripe_name, th, 0);
                if (rc != 0)
                        GOTO(out, rc);
 
-               rc = dt_ref_add(env, dt_object_child(dt), th);
+               rc = lod_sub_object_ref_add(env, dt_object_child(dt), th);
                if (rc != 0)
                        GOTO(out, rc);
        }
 
-       rc = dt_xattr_set(env, dt_object_child(dt), &lmv_buf, XATTR_NAME_LMV,
-                         fl, th, capa);
-
+       if (!OBD_FAIL_CHECK(OBD_FAIL_LFSCK_LOST_MASTER_LMV))
+               rc = lod_sub_object_xattr_set(env, dt_object_child(dt),
+                                             &lmv_buf, XATTR_NAME_LMV, fl, th);
 out:
        if (slave_lmm != NULL)
                OBD_FREE_PTR(slave_lmm);
@@ -2199,12 +2599,34 @@ out:
        RETURN(rc);
 }
 
-int lod_dir_striping_create_internal(const struct lu_env *env,
-                                    struct dt_object *dt,
-                                    struct lu_attr *attr,
-                                    struct dt_object_format *dof,
-                                    struct thandle *th,
-                                    bool declare)
+/**
+ * Helper function to declare/execute creation of a striped directory
+ *
+ * Called in declare/create object path, prepare striping for a directory
+ * and prepare defaults data striping for the objects to be created in
+ * that directory. Notice the function calls "declaration" or "execution"
+ * methods depending on \a declare param. This is a consequence of the
+ * current approach while we don't have natural distributed transactions:
+ * we basically execute non-local updates in the declare phase. So, the
+ * arguments for the both phases are the same and this is the reason for
+ * this function to exist.
+ *
+ * \param[in] env      execution environment
+ * \param[in] dt       object
+ * \param[in] attr     attributes the stripes will be created with
+ * \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
+ *
+ * \retval             0 on success
+ * \retval             negative if failed
+ */
+static int lod_dir_striping_create_internal(const struct lu_env *env,
+                                           struct dt_object *dt,
+                                           struct lu_attr *attr,
+                                           struct dt_object_format *dof,
+                                           struct thandle *th,
+                                           bool declare)
 {
        struct lod_thread_info  *info = lod_env_info(env);
        struct lod_object       *lo = lod_dt_obj(dt);
@@ -2237,14 +2659,13 @@ int lod_dir_striping_create_internal(const struct lu_env *env,
                                                       &info->lti_buf, dof, th);
                else
                        rc = lod_xattr_set_lmv(env, dt, &info->lti_buf,
-                                              XATTR_NAME_LMV, 0, th,
-                                              BYPASS_CAPA);
+                                              XATTR_NAME_LMV, 0, th);
                if (rc != 0)
                        RETURN(rc);
        }
 
        /* Transfer default LMV striping from the parent */
-       if (lo->ldo_dir_striping_cached &&
+       if (lo->ldo_dir_def_striping_set &&
            !LMVEA_DELETE_VALUES(lo->ldo_dir_def_stripenr,
                                 lo->ldo_dir_def_stripe_offset)) {
                struct lmv_user_md_v1 *v1 = info->lti_ea_store;
@@ -2275,16 +2696,17 @@ int lod_dir_striping_create_internal(const struct lu_env *env,
                        rc = lod_xattr_set_default_lmv_on_dir(env, dt,
                                                  &info->lti_buf,
                                                  XATTR_NAME_DEFAULT_LMV, 0,
-                                                 th, BYPASS_CAPA);
+                                                 th);
                if (rc != 0)
                        RETURN(rc);
        }
 
        /* Transfer default LOV striping from the parent */
-       if (lo->ldo_striping_cached &&
+       if (lo->ldo_def_striping_set &&
            !LOVEA_DELETE_VALUES(lo->ldo_def_stripe_size,
                                 lo->ldo_def_stripenr,
-                                lo->ldo_def_stripe_offset)) {
+                                lo->ldo_def_stripe_offset,
+                                lo->ldo_pool)) {
                struct lov_user_md_v3 *v3 = info->lti_ea_store;
 
                if (info->lti_ea_store_size < sizeof(*v3)) {
@@ -2311,8 +2733,7 @@ int lod_dir_striping_create_internal(const struct lu_env *env,
                                                       XATTR_NAME_LOV, 0, th);
                else
                        rc = lod_xattr_set_lov_on_dir(env, dt, &info->lti_buf,
-                                                     XATTR_NAME_LOV, 0, th,
-                                                     BYPASS_CAPA);
+                                                     XATTR_NAME_LOV, 0, th);
                if (rc != 0)
                        RETURN(rc);
        }
@@ -2335,13 +2756,37 @@ 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);
+       struct lod_object *lo = lod_dt_obj(dt);
+       int rc;
+
+       rc = lod_dir_striping_create_internal(env, dt, attr, dof, th, false);
+       if (rc == 0)
+               lo->ldo_striping_cached = 1;
+
+       return rc;
 }
 
+/**
+ * Implementation of dt_object_operations::do_xattr_set.
+ *
+ * Sets specified extended attribute on the object. Three types of EAs are
+ * special:
+ *   LOV EA - stores striping for a regular file or default striping (when set
+ *           on a directory)
+ *   LMV EA - stores a marker for the striped directories
+ *   DMV EA - stores default directory striping
+ *
+ * When striping is applied to a non-striped existing object (this is called
+ * late striping), then LOD notices the caller wants to turn the object into a
+ * striped one. The stripe objects are created and appropriate EA is set:
+ * LOV EA storing all the stripes directly or LMV EA storing just a small header
+ * with striping configuration.
+ *
+ * \see dt_object_operations::do_xattr_set() in the API description for details.
+ */
 static int lod_xattr_set(const struct lu_env *env,
                         struct dt_object *dt, const struct lu_buf *buf,
-                        const char *name, int fl, struct thandle *th,
-                        struct lustre_capa *capa)
+                        const char *name, int fl, struct thandle *th)
 {
        struct dt_object        *next = dt_object_child(dt);
        int                      rc;
@@ -2353,7 +2798,8 @@ static int lod_xattr_set(const struct lu_env *env,
 
                if (lmm != NULL && le32_to_cpu(lmm->lmv_hash_type) &
                                                LMV_HASH_FLAG_MIGRATION)
-                       rc = dt_xattr_set(env, next, buf, name, fl, th, capa);
+                       rc = lod_sub_object_xattr_set(env, next, buf, name, fl,
+                                                     th);
                else
                        rc = lod_dir_striping_create(env, dt, NULL, NULL, th);
 
@@ -2363,60 +2809,155 @@ 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, capa);
+               rc = lod_xattr_set_lov_on_dir(env, dt, buf, name, fl, th);
                RETURN(rc);
        } else if (S_ISDIR(dt->do_lu.lo_header->loh_attr) &&
                   strcmp(name, XATTR_NAME_DEFAULT_LMV) == 0) {
                /* default LMVEA */
                rc = lod_xattr_set_default_lmv_on_dir(env, dt, buf, name, fl,
-                                                     th, capa);
+                                                     th);
                RETURN(rc);
        } else if (S_ISREG(dt->do_lu.lo_header->loh_attr) &&
                   !strcmp(name, XATTR_NAME_LOV)) {
                /* in case of lov EA swap, just set it
                 * if not, it is a replay so check striping match what we
                 * already have during req replay, declare_xattr_set()
-                * defines striping, then create() does the work
-               */
+                * defines striping, then create() does the work */
                if (fl & LU_XATTR_REPLACE) {
                        /* free stripes, then update disk */
                        lod_object_free_striping(env, lod_dt_obj(dt));
-                       rc = dt_xattr_set(env, next, buf, name, fl, th, capa);
+
+                       rc = lod_sub_object_xattr_set(env, next, buf, name,
+                                                     fl, th);
+               } else if (dt_object_remote(dt)) {
+                       /* This only happens during migration, see
+                        * mdd_migrate_create(), in which Master MDT will
+                        * create a remote target object, and only set
+                        * (migrating) stripe EA on the remote object,
+                        * and does not need creating each stripes. */
+                       rc = lod_sub_object_xattr_set(env, next, buf, name,
+                                                     fl, th);
                } else {
                        rc = lod_striping_create(env, dt, NULL, NULL, th);
                }
                RETURN(rc);
+       } else if (strcmp(name, XATTR_NAME_FID) == 0) {
+               rc = lod_object_replace_parent_fid(env, dt, th, false);
+
+               RETURN(rc);
        }
 
        /* then all other xattr */
-       rc = lod_xattr_set_internal(env, dt, buf, name, fl, th, capa);
+       rc = lod_xattr_set_internal(env, dt, buf, name, fl, th);
 
        RETURN(rc);
 }
 
+/**
+ * Implementation of dt_object_operations::do_declare_xattr_del.
+ *
+ * \see dt_object_operations::do_declare_xattr_del() in the API description
+ * for details.
+ */
 static int lod_declare_xattr_del(const struct lu_env *env,
                                 struct dt_object *dt, const char *name,
                                 struct thandle *th)
 {
-       return dt_declare_xattr_del(env, dt_object_child(dt), name, th);
+       struct lod_object       *lo = lod_dt_obj(dt);
+       int                     rc;
+       int                     i;
+       ENTRY;
+
+       rc = lod_sub_object_declare_xattr_del(env, dt_object_child(dt),
+                                             name, th);
+       if (rc != 0)
+               RETURN(rc);
+
+       if (!S_ISDIR(dt->do_lu.lo_header->loh_attr))
+               RETURN(0);
+
+       /* set xattr to each stripes, if needed */
+       rc = lod_load_striping(env, lo);
+       if (rc != 0)
+               RETURN(rc);
+
+       if (lo->ldo_stripenr == 0)
+               RETURN(0);
+
+       for (i = 0; i < lo->ldo_stripenr; i++) {
+               LASSERT(lo->ldo_stripe[i]);
+               rc = lod_sub_object_declare_xattr_del(env, lo->ldo_stripe[i],
+                                                     name, th);
+               if (rc != 0)
+                       break;
+       }
+
+       RETURN(rc);
 }
 
+/**
+ * Implementation of dt_object_operations::do_xattr_del.
+ *
+ * If EA storing a regular striping is being deleted, then release
+ * all the references to the stripe objects in core.
+ *
+ * \see dt_object_operations::do_xattr_del() in the API description for details.
+ */
 static int lod_xattr_del(const struct lu_env *env, struct dt_object *dt,
-                        const char *name, struct thandle *th,
-                        struct lustre_capa *capa)
+                        const char *name, struct thandle *th)
 {
+       struct dt_object        *next = dt_object_child(dt);
+       struct lod_object       *lo = lod_dt_obj(dt);
+       int                     rc;
+       int                     i;
+       ENTRY;
+
        if (!strcmp(name, XATTR_NAME_LOV))
                lod_object_free_striping(env, lod_dt_obj(dt));
-       return dt_xattr_del(env, dt_object_child(dt), name, th, capa);
+
+       rc = lod_sub_object_xattr_del(env, next, name, th);
+       if (rc != 0 || !S_ISDIR(dt->do_lu.lo_header->loh_attr))
+               RETURN(rc);
+
+       if (lo->ldo_stripenr == 0)
+               RETURN(0);
+
+       for (i = 0; i < lo->ldo_stripenr; i++) {
+               LASSERT(lo->ldo_stripe[i]);
+
+               rc = lod_sub_object_xattr_del(env, lo->ldo_stripe[i], name, th);
+               if (rc != 0)
+                       break;
+       }
+
+       RETURN(rc);
 }
 
+/**
+ * Implementation of dt_object_operations::do_xattr_list.
+ *
+ * \see dt_object_operations::do_xattr_list() in the API description
+ * for details.
+ */
 static int lod_xattr_list(const struct lu_env *env,
-                         struct dt_object *dt, struct lu_buf *buf,
-                         struct lustre_capa *capa)
+                         struct dt_object *dt, const struct lu_buf *buf)
 {
-       return dt_xattr_list(env, dt_object_child(dt), buf, capa);
+       return dt_xattr_list(env, dt_object_child(dt), buf);
 }
 
+/**
+ * Initialize a pool the object belongs to.
+ *
+ * When a striped object is being created, striping configuration
+ * may demand the stripes are allocated on a limited set of the
+ * targets. These limited sets are known as "pools". So we copy
+ * a pool name into the object and later actual creation methods
+ * (like lod_object_create()) will use this information to allocate
+ * the stripes properly.
+ *
+ * \param[in] o                object
+ * \param[in] pool     pool name
+ */
 int lod_object_set_pool(struct lod_object *o, char *pool)
 {
        int len;
@@ -2442,6 +2983,18 @@ static inline int lod_object_will_be_striped(int is_reg, const struct lu_fid *fi
 }
 
 
+/**
+ * Cache default regular striping in the object.
+ *
+ * To improve performance of striped regular object creation we cache
+ * default LOV striping (if it exists) in the parent directory object.
+ *
+ * \param[in] env              execution environment
+ * \param[in] lp               object
+ *
+ * \retval             0 on success
+ * \retval             negative if failed
+ */
 static int lod_cache_parent_lov_striping(const struct lu_env *env,
                                         struct lod_object *lp)
 {
@@ -2461,7 +3014,7 @@ static int lod_cache_parent_lov_striping(const struct lu_env *env,
        if (rc < (typeof(rc))sizeof(struct lov_user_md)) {
                /* don't lookup for non-existing or invalid striping */
                lp->ldo_def_striping_set = 0;
-               lp->ldo_striping_cached = 1;
+               lp->ldo_def_striping_cached = 1;
                lp->ldo_def_stripe_size = 0;
                lp->ldo_def_stripenr = 0;
                lp->ldo_def_stripe_offset = (typeof(v1->lmm_stripe_offset))(-1);
@@ -2491,7 +3044,7 @@ static int lod_cache_parent_lov_striping(const struct lu_env *env,
        lp->ldo_def_stripenr = v1->lmm_stripe_count;
        lp->ldo_def_stripe_size = v1->lmm_stripe_size;
        lp->ldo_def_stripe_offset = v1->lmm_stripe_offset;
-       lp->ldo_striping_cached = 1;
+       lp->ldo_def_striping_cached = 1;
        lp->ldo_def_striping_set = 1;
        if (v1->lmm_magic == LOV_USER_MAGIC_V3) {
                /* XXX: sanity check here */
@@ -2506,6 +3059,18 @@ unlock:
 }
 
 
+/**
+ * Cache default directory striping in the object.
+ *
+ * To improve performance of striped directory creation we cache default
+ * directory striping (if it exists) in the parent directory object.
+ *
+ * \param[in] env              execution environment
+ * \param[in] lp               object
+ *
+ * \retval             0 on success
+ * \retval             negative if failed
+ */
 static int lod_cache_parent_lmv_striping(const struct lu_env *env,
                                         struct lod_object *lp)
 {
@@ -2524,7 +3089,7 @@ static int lod_cache_parent_lmv_striping(const struct lu_env *env,
        if (rc < (typeof(rc))sizeof(struct lmv_user_md)) {
                /* don't lookup for non-existing or invalid striping */
                lp->ldo_dir_def_striping_set = 0;
-               lp->ldo_dir_striping_cached = 1;
+               lp->ldo_dir_def_striping_cached = 1;
                lp->ldo_dir_def_stripenr = 0;
                lp->ldo_dir_def_stripe_offset =
                                        (typeof(v1->lum_stripe_offset))(-1);
@@ -2539,7 +3104,7 @@ static int lod_cache_parent_lmv_striping(const struct lu_env *env,
        lp->ldo_dir_def_stripe_offset = le32_to_cpu(v1->lum_stripe_offset);
        lp->ldo_dir_def_hash_type = le32_to_cpu(v1->lum_hash_type);
        lp->ldo_dir_def_striping_set = 1;
-       lp->ldo_dir_striping_cached = 1;
+       lp->ldo_dir_def_striping_cached = 1;
 
        EXIT;
 unlock:
@@ -2547,6 +3112,22 @@ unlock:
        return rc;
 }
 
+/**
+ * Cache default striping in the object.
+ *
+ * To improve performance of striped object creation we cache default striping
+ * (if it exists) in the parent directory object. We always cache default
+ * striping for the regular files (stored in LOV EA) and we cache default
+ * striping for the directories if requested by \a child_mode (when a new
+ * directory is being created).
+ *
+ * \param[in] env              execution environment
+ * \param[in] lp               object
+ * \param[in] child_mode       new object's mode
+ *
+ * \retval             0 on success
+ * \retval             negative if failed
+ */
 static int lod_cache_parent_striping(const struct lu_env *env,
                                     struct lod_object *lp,
                                     umode_t child_mode)
@@ -2554,11 +3135,7 @@ static int lod_cache_parent_striping(const struct lu_env *env,
        int rc = 0;
        ENTRY;
 
-       rc = lod_load_striping(env, lp);
-       if (rc != 0)
-               RETURN(rc);
-
-       if (!lp->ldo_striping_cached) {
+       if (!lp->ldo_def_striping_cached) {
                /* we haven't tried to get default striping for
                 * the directory yet, let's cache it in the object */
                rc = lod_cache_parent_lov_striping(env, lp);
@@ -2566,14 +3143,27 @@ static int lod_cache_parent_striping(const struct lu_env *env,
                        RETURN(rc);
        }
 
-       if (S_ISDIR(child_mode) && !lp->ldo_dir_striping_cached)
+       /* If the parent is on the remote MDT, we should always
+        * try to refresh the default stripeEA cache, because we
+        * do not cache default striping information for remote
+        * object. */
+       if (S_ISDIR(child_mode) && (!lp->ldo_dir_def_striping_cached ||
+                                   dt_object_remote(&lp->ldo_obj)))
                rc = lod_cache_parent_lmv_striping(env, lp);
 
        RETURN(rc);
 }
 
 /**
- * used to transfer default striping data to the object being created
+ * Implementation of dt_object_operations::do_ah_init.
+ *
+ * This method is used to make a decision on the striping configuration for the
+ * object being created. It can be taken from the \a parent object if it exists,
+ * or filesystem's default. The resulting configuration (number of stripes,
+ * stripe size/offset, pool name, etc) is stored in the object itself and will
+ * be used by the methods like ->doo_declare_create().
+ *
+ * \see dt_object_operations::do_ah_init() in the API description for details.
  */
 static void lod_ah_init(const struct lu_env *env,
                        struct dt_allocation_hint *ah,
@@ -2606,14 +3196,8 @@ static void lod_ah_init(const struct lu_env *env,
        LASSERT(lc->ldo_stripenr == 0);
        LASSERT(lc->ldo_stripe == NULL);
 
-       /*
-        * local object may want some hints
-        * in case of late striping creation, ->ah_init()
-        * can be called with local object existing
-        */
-       if (!dt_object_exists(nextc) || dt_object_remote(nextc))
-               nextc->do_ops->do_ah_init(env, ah, dt_object_remote(nextp) ?
-                                         NULL : nextp, nextc, child_mode);
+       if (!dt_object_exists(nextc))
+               nextc->do_ops->do_ah_init(env, ah, nextp, nextc, child_mode);
 
        if (S_ISDIR(child_mode)) {
                if (lc->ldo_dir_stripe == NULL) {
@@ -2622,6 +3206,7 @@ static void lod_ah_init(const struct lu_env *env,
                                return;
                }
 
+               LASSERT(lp != NULL);
                if (lp->ldo_dir_stripe == NULL) {
                        OBD_ALLOC_PTR(lp->ldo_dir_stripe);
                        if (lp->ldo_dir_stripe == NULL)
@@ -2633,14 +3218,14 @@ static void lod_ah_init(const struct lu_env *env,
                        return;
 
                /* transfer defaults to new directory */
-               if (lp->ldo_striping_cached) {
+               if (lp->ldo_def_striping_set) {
                        if (lp->ldo_pool)
                                lod_object_set_pool(lc, lp->ldo_pool);
                        lc->ldo_def_stripenr = lp->ldo_def_stripenr;
                        lc->ldo_def_stripe_size = lp->ldo_def_stripe_size;
                        lc->ldo_def_stripe_offset = lp->ldo_def_stripe_offset;
-                       lc->ldo_striping_cached = 1;
                        lc->ldo_def_striping_set = 1;
+                       lc->ldo_def_striping_cached = 1;
                        CDEBUG(D_OTHER, "inherite EA sz:%d off:%d nr:%d\n",
                               (int)lc->ldo_def_stripe_size,
                               (int)lc->ldo_def_stripe_offset,
@@ -2648,14 +3233,14 @@ static void lod_ah_init(const struct lu_env *env,
                }
 
                /* transfer dir defaults to new directory */
-               if (lp->ldo_dir_striping_cached) {
+               if (lp->ldo_dir_def_striping_set) {
                        lc->ldo_dir_def_stripenr = lp->ldo_dir_def_stripenr;
                        lc->ldo_dir_def_stripe_offset =
                                                  lp->ldo_dir_def_stripe_offset;
                        lc->ldo_dir_def_hash_type =
                                                  lp->ldo_dir_def_hash_type;
-                       lc->ldo_dir_striping_cached = 1;
                        lc->ldo_dir_def_striping_set = 1;
+                       lc->ldo_dir_def_striping_cached = 1;
                        CDEBUG(D_INFO, "inherit default EA nr:%d off:%d t%u\n",
                               (int)lc->ldo_dir_def_stripenr,
                               (int)lc->ldo_dir_def_stripe_offset,
@@ -2718,7 +3303,7 @@ static void lod_ah_init(const struct lu_env *env,
        if (likely(parent)) {
                lod_cache_parent_striping(env, lp, child_mode);
 
-               lc->ldo_def_stripe_offset = (__u16) -1;
+               lc->ldo_def_stripe_offset = LOV_OFFSET_DEFAULT;
 
                if (lp->ldo_def_striping_set) {
                        if (lp->ldo_pool)
@@ -2754,11 +3339,21 @@ out:
 }
 
 #define ll_do_div64(aaa,bbb)    do_div((aaa), (bbb))
-/*
- * this function handles a special case when truncate was done
- * on a stripeless object and now striping is being created
- * we can't lose that size, so we have to propagate it to newly
- * created object
+/**
+ * Size initialization on late striping.
+ *
+ * Propagate the size of a truncated object to a deferred striping.
+ * This function handles a special case when truncate was done on a
+ * non-striped object and now while the striping is being created
+ * we can't lose that size, so we have to propagate it to the stripes
+ * being created.
+ *
+ * \param[in] env      execution environment
+ * \param[in] dt       object
+ * \param[in] th       transaction handle
+ *
+ * \retval             0 on success
+ * \retval             negative if failed
  */
 static int lod_declare_init_size(const struct lu_env *env,
                                 struct dt_object *dt, struct thandle *th)
@@ -2774,7 +3369,7 @@ static int lod_declare_init_size(const struct lu_env *env,
        LASSERT(lo->ldo_stripe || lo->ldo_stripenr == 0);
        LASSERT(lo->ldo_stripe_size > 0);
 
-       rc = dt_attr_get(env, next, attr, BYPASS_CAPA);
+       rc = dt_attr_get(env, next, attr);
        LASSERT(attr->la_valid & LA_SIZE);
        if (rc)
                RETURN(rc);
@@ -2794,13 +3389,30 @@ static int lod_declare_init_size(const struct lu_env *env,
        attr->la_valid = LA_SIZE;
        attr->la_size = size;
 
-       rc = dt_declare_attr_set(env, lo->ldo_stripe[stripe], attr, th);
+       rc = lod_sub_object_declare_attr_set(env, lo->ldo_stripe[stripe], attr,
+                                            th);
 
        RETURN(rc);
 }
 
 /**
- * Create declaration of striped object
+ * Declare creation of striped object.
+ *
+ * The function declares creation stripes for a regular object. The function
+ * also declares whether the stripes will be created with non-zero size if
+ * previously size was set non-zero on the master object. If object \a dt is
+ * not local, then only fully defined striping can be applied in \a lovea.
+ * Otherwise \a lovea can be in the form of pattern, see lod_qos_parse_config()
+ * for the details.
+ *
+ * \param[in] env      execution environment
+ * \param[in] dt       object
+ * \param[in] attr     attributes the stripes will be created with
+ * \param[in] lovea    a buffer containing striping description
+ * \param[in] th       transaction handle
+ *
+ * \retval             0 on success
+ * \retval             negative if failed
  */
 int lod_declare_striped_object(const struct lu_env *env, struct dt_object *dt,
                               struct lu_attr *attr,
@@ -2844,8 +3456,8 @@ int lod_declare_striped_object(const struct lu_env *env, struct dt_object *dt,
                info->lti_buf = *lovea;
        }
 
-       rc = dt_declare_xattr_set(env, next, &info->lti_buf,
-                                 XATTR_NAME_LOV, 0, th);
+       rc = lod_sub_object_declare_xattr_set(env, next, &info->lti_buf,
+                                             XATTR_NAME_LOV, 0, th);
        if (rc)
                GOTO(out, rc);
 
@@ -2861,6 +3473,17 @@ out:
        RETURN(rc);
 }
 
+/**
+ * Implementation of dt_object_operations::do_declare_create.
+ *
+ * The method declares creation of a new object. If the object will be striped,
+ * then helper functions are called to find FIDs for the stripes, declare
+ * creation of the stripes and declare initialization of the striping
+ * information to be stored in the master object.
+ *
+ * \see dt_object_operations::do_declare_create() in the API description
+ * for details.
+ */
 static int lod_declare_object_create(const struct lu_env *env,
                                     struct dt_object *dt,
                                     struct lu_attr *attr,
@@ -2880,15 +3503,17 @@ static int lod_declare_object_create(const struct lu_env *env,
        /*
         * first of all, we declare creation of local object
         */
-       rc = dt_declare_create(env, next, attr, hint, dof, th);
-       if (rc)
+       rc = lod_sub_object_declare_create(env, next, attr, hint, dof, th);
+       if (rc != 0)
                GOTO(out, rc);
 
        if (dof->dof_type == DFT_SYM)
                dt->do_body_ops = &lod_body_lnk_ops;
+       else if (dof->dof_type == DFT_REGULAR)
+               dt->do_body_ops = &lod_body_ops;
 
        /*
-        * it's lod_ah_init() who has decided the object will striped
+        * it's lod_ah_init() that has decided the object will be striped
         */
        if (dof->dof_type == DFT_REGULAR) {
                /* callers don't want stripes */
@@ -2901,6 +3526,34 @@ static int lod_declare_object_create(const struct lu_env *env,
                        rc = lod_declare_striped_object(env, dt, attr,
                                                        NULL, th);
        } else if (dof->dof_type == DFT_DIR) {
+               struct seq_server_site *ss;
+
+               ss = lu_site2seq(dt->do_lu.lo_dev->ld_site);
+
+               /* If the parent has default stripeEA, and client
+                * did not find it before sending create request,
+                * then MDT will return -EREMOTE, and client will
+                * retrieve the default stripeEA and re-create the
+                * sub directory.
+                *
+                * Note: if dah_eadata != NULL, it means creating the
+                * striped directory with specified stripeEA, then it
+                * should ignore the default stripeEA */
+               if (hint != NULL && hint->dah_eadata == NULL) {
+                       if (OBD_FAIL_CHECK(OBD_FAIL_MDS_STALE_DIR_LAYOUT))
+                               GOTO(out, rc = -EREMOTE);
+
+                       if (lo->ldo_dir_stripe_offset == -1) {
+                               /* child and parent should be in the same MDT */
+                               if (hint->dah_parent != NULL &&
+                                   dt_object_remote(hint->dah_parent))
+                                       GOTO(out, rc = -EREMOTE);
+                       } else if (lo->ldo_dir_stripe_offset !=
+                                  ss->ss_node_id) {
+                               GOTO(out, rc = -EREMOTE);
+                       }
+               }
+
                /* Orphan object (like migrating object) does not have
                 * lod_dir_stripe, see lod_ah_init */
                if (lo->ldo_dir_stripe != NULL)
@@ -2911,6 +3564,25 @@ out:
        RETURN(rc);
 }
 
+/**
+ * Creation of a striped regular object.
+ *
+ * The function is called to create the stripe objects for a regular
+ * striped file. This can happen at the initial object creation or
+ * when the caller asks LOD to do so using ->do_xattr_set() method
+ * (so called late striping). Notice all the information are already
+ * prepared in the form of the list of objects (ldo_stripe field).
+ * This is done during declare phase.
+ *
+ * \param[in] env      execution environment
+ * \param[in] dt       object
+ * \param[in] attr     attributes the stripes will be created with
+ * \param[in] dof      format of stripes (see OSD API description)
+ * \param[in] th       transaction handle
+ *
+ * \retval             0 on success
+ * \retval             negative if failed
+ */
 int lod_striping_create(const struct lu_env *env, struct dt_object *dt,
                        struct lu_attr *attr, struct dt_object_format *dof,
                        struct thandle *th)
@@ -2924,29 +3596,42 @@ int lod_striping_create(const struct lu_env *env, struct dt_object *dt,
        /* create all underlying objects */
        for (i = 0; i < lo->ldo_stripenr; i++) {
                LASSERT(lo->ldo_stripe[i]);
-               rc = dt_create(env, lo->ldo_stripe[i], attr, NULL, dof, th);
-
+               rc = lod_sub_object_create(env, lo->ldo_stripe[i], attr, NULL,
+                                          dof, th);
                if (rc)
                        break;
        }
-       if (rc == 0)
+
+       if (rc == 0) {
                rc = lod_generate_and_set_lovea(env, lo, th);
+               if (rc == 0)
+                       lo->ldo_striping_cached = 1;
+       }
 
        RETURN(rc);
 }
 
+/**
+ * Implementation of dt_object_operations::do_create.
+ *
+ * If any of preceeding methods (like ->do_declare_create(),
+ * ->do_ah_init(), etc) chose to create a striped object,
+ * then this method will create the master and the stripes.
+ *
+ * \see dt_object_operations::do_create() in the API description for details.
+ */
 static int lod_object_create(const struct lu_env *env, struct dt_object *dt,
                             struct lu_attr *attr,
                             struct dt_allocation_hint *hint,
                             struct dt_object_format *dof, struct thandle *th)
 {
-       struct dt_object   *next = dt_object_child(dt);
        struct lod_object  *lo = lod_dt_obj(dt);
        int                 rc;
        ENTRY;
 
        /* create local object */
-       rc = dt_create(env, next, attr, hint, dof, th);
+       rc = lod_sub_object_create(env, dt_object_child(dt), attr, hint, dof,
+                                  th);
        if (rc != 0)
                RETURN(rc);
 
@@ -2957,6 +3642,17 @@ static int lod_object_create(const struct lu_env *env, struct dt_object *dt,
        RETURN(rc);
 }
 
+/**
+ * Implementation of dt_object_operations::do_declare_destroy.
+ *
+ * If the object is a striped directory, then the function declares reference
+ * removal from the master object (this is an index) to the stripes and declares
+ * destroy of all the stripes. In all the cases, it declares an intention to
+ * destroy the object itself.
+ *
+ * \see dt_object_operations::do_declare_destroy() in the API description
+ * for details.
+ */
 static int lod_declare_object_destroy(const struct lu_env *env,
                                      struct dt_object *dt,
                                      struct thandle *th)
@@ -2985,22 +3681,24 @@ static int lod_declare_object_destroy(const struct lu_env *env,
                        RETURN(rc);
 
                for (i = 0; i < lo->ldo_stripenr; i++) {
-                       rc = dt_declare_ref_del(env, next, th);
+                       rc = lod_sub_object_declare_ref_del(env, next, th);
                        if (rc != 0)
                                RETURN(rc);
+
                        snprintf(stripe_name, sizeof(info->lti_key), DFID":%d",
                                PFID(lu_object_fid(&lo->ldo_stripe[i]->do_lu)),
                                i);
-                       rc = dt_declare_delete(env, next,
+                       rc = lod_sub_object_declare_delete(env, next,
                                        (const struct dt_key *)stripe_name, th);
                        if (rc != 0)
                                RETURN(rc);
                }
        }
+
        /*
         * we declare destroy for the local object
         */
-       rc = dt_declare_destroy(env, next, th);
+       rc = lod_sub_object_declare_destroy(env, next, th);
        if (rc)
                RETURN(rc);
 
@@ -3009,16 +3707,31 @@ static int lod_declare_object_destroy(const struct lu_env *env,
 
        /* declare destroy all striped objects */
        for (i = 0; i < lo->ldo_stripenr; i++) {
-               if (likely(lo->ldo_stripe[i] != NULL)) {
-                       rc = dt_declare_destroy(env, lo->ldo_stripe[i], th);
-                       if (rc != 0)
-                               break;
-               }
+               if (lo->ldo_stripe[i] == NULL)
+                       continue;
+
+               if (S_ISDIR(dt->do_lu.lo_header->loh_attr))
+                       rc = lod_sub_object_declare_ref_del(env,
+                                       lo->ldo_stripe[i], th);
+
+               rc = lod_sub_object_declare_destroy(env, lo->ldo_stripe[i],
+                                       th);
+               if (rc != 0)
+                       break;
        }
 
        RETURN(rc);
 }
 
+/**
+ * Implementation of dt_object_operations::do_destroy.
+ *
+ * If the object is a striped directory, then the function removes references
+ * from the master object (this is an index) to the stripes and destroys all
+ * the stripes. In all the cases, the function destroys the object itself.
+ *
+ * \see dt_object_operations::do_destroy() in the API description for details.
+ */
 static int lod_object_destroy(const struct lu_env *env,
                struct dt_object *dt, struct thandle *th)
 {
@@ -3038,7 +3751,7 @@ static int lod_object_destroy(const struct lu_env *env,
                        RETURN(rc);
 
                for (i = 0; i < lo->ldo_stripenr; i++) {
-                       rc = dt_ref_del(env, next, th);
+                       rc = lod_sub_object_ref_del(env, next, th);
                        if (rc != 0)
                                RETURN(rc);
 
@@ -3050,14 +3763,14 @@ static int lod_object_destroy(const struct lu_env *env,
                               PFID(lu_object_fid(&dt->do_lu)), stripe_name,
                               PFID(lu_object_fid(&lo->ldo_stripe[i]->do_lu)));
 
-                       rc = dt_delete(env, next,
-                                      (const struct dt_key *)stripe_name,
-                                      th, BYPASS_CAPA);
+                       rc = lod_sub_object_delete(env, next,
+                                      (const struct dt_key *)stripe_name, th);
                        if (rc != 0)
                                RETURN(rc);
                }
        }
-       rc = dt_destroy(env, next, th);
+
+       rc = lod_sub_object_destroy(env, next, th);
        if (rc != 0)
                RETURN(rc);
 
@@ -3069,7 +3782,17 @@ static int lod_object_destroy(const struct lu_env *env,
                if (likely(lo->ldo_stripe[i] != NULL) &&
                    (!OBD_FAIL_CHECK(OBD_FAIL_LFSCK_LOST_SPEOBJ) ||
                     i == cfs_fail_val)) {
-                       rc = dt_destroy(env, lo->ldo_stripe[i], th);
+                       if (S_ISDIR(dt->do_lu.lo_header->loh_attr)) {
+                               dt_write_lock(env, lo->ldo_stripe[i],
+                                             MOR_TGT_CHILD);
+                               rc = lod_sub_object_ref_del(env,
+                                               lo->ldo_stripe[i], th);
+                               dt_write_unlock(env, lo->ldo_stripe[i]);
+                               if (rc != 0)
+                                       break;
+                       }
+
+                       rc = lod_sub_object_destroy(env, lo->ldo_stripe[i], th);
                        if (rc != 0)
                                break;
                }
@@ -3078,37 +3801,58 @@ static int lod_object_destroy(const struct lu_env *env,
        RETURN(rc);
 }
 
+/**
+ * Implementation of dt_object_operations::do_declare_ref_add.
+ *
+ * \see dt_object_operations::do_declare_ref_add() in the API description
+ * for details.
+ */
 static int lod_declare_ref_add(const struct lu_env *env,
                               struct dt_object *dt, struct thandle *th)
 {
-       return dt_declare_ref_add(env, dt_object_child(dt), th);
+       return lod_sub_object_declare_ref_add(env, dt_object_child(dt), th);
 }
 
+/**
+ * Implementation of dt_object_operations::do_ref_add.
+ *
+ * \see dt_object_operations::do_ref_add() in the API description for details.
+ */
 static int lod_ref_add(const struct lu_env *env,
                       struct dt_object *dt, struct thandle *th)
 {
-       return dt_ref_add(env, dt_object_child(dt), th);
+       return lod_sub_object_ref_add(env, dt_object_child(dt), th);
 }
 
+/**
+ * Implementation of dt_object_operations::do_declare_ref_del.
+ *
+ * \see dt_object_operations::do_declare_ref_del() in the API description
+ * for details.
+ */
 static int lod_declare_ref_del(const struct lu_env *env,
                               struct dt_object *dt, struct thandle *th)
 {
-       return dt_declare_ref_del(env, dt_object_child(dt), th);
+       return lod_sub_object_declare_ref_del(env, dt_object_child(dt), th);
 }
 
+/**
+ * Implementation of dt_object_operations::do_ref_del
+ *
+ * \see dt_object_operations::do_ref_del() in the API description for details.
+ */
 static int lod_ref_del(const struct lu_env *env,
                       struct dt_object *dt, struct thandle *th)
 {
-       return dt_ref_del(env, dt_object_child(dt), th);
-}
-
-static struct obd_capa *lod_capa_get(const struct lu_env *env,
-                                    struct dt_object *dt,
-                                    struct lustre_capa *old, __u64 opc)
-{
-       return dt_capa_get(env, dt_object_child(dt), old, opc);
+       return lod_sub_object_ref_del(env, dt_object_child(dt), th);
 }
 
+/**
+ * Implementation of dt_object_operations::do_object_sync.
+ *
+ * \see dt_object_operations::do_object_sync() in the API description
+ * for details.
+ */
 static int lod_object_sync(const struct lu_env *env, struct dt_object *dt,
                           __u64 start, __u64 end)
 {
@@ -3120,12 +3864,25 @@ struct lod_slave_locks  {
        struct lustre_handle    lsl_handle[0];
 };
 
+/**
+ * Release LDLM locks on the stripes of a striped directory.
+ *
+ * Iterates over all the locks taken on the stripe objects and
+ * release them using ->do_object_unlock() method.
+ *
+ * \param[in] env      execution environment
+ * \param[in] dt       striped object
+ * \param[in] einfo    lock description
+ * \param[in] policy   data describing requested lock
+ *
+ * \retval             0 on success
+ * \retval             negative if failed
+ */
 static int lod_object_unlock_internal(const struct lu_env *env,
                                      struct dt_object *dt,
                                      struct ldlm_enqueue_info *einfo,
                                      ldlm_policy_data_t *policy)
 {
-       struct lod_object       *lo = lod_dt_obj(dt);
        struct lod_slave_locks  *slave_locks = einfo->ei_cbdata;
        int                     rc = 0;
        int                     i;
@@ -3135,20 +3892,22 @@ static int lod_object_unlock_internal(const struct lu_env *env,
                RETURN(0);
 
        for (i = 1; i < slave_locks->lsl_lock_count; i++) {
-               if (lustre_handle_is_used(&slave_locks->lsl_handle[i])) {
-                       int     rc1;
-
-                       einfo->ei_cbdata = &slave_locks->lsl_handle[i];
-                       rc1 = dt_object_unlock(env, lo->ldo_stripe[i], einfo,
-                                              policy);
-                       if (rc1 < 0)
-                               rc = rc == 0 ? rc1 : rc;
-               }
+               if (lustre_handle_is_used(&slave_locks->lsl_handle[i]))
+                       ldlm_lock_decref(&slave_locks->lsl_handle[i],
+                                        einfo->ei_mode);
        }
 
        RETURN(rc);
 }
 
+/**
+ * Implementation of dt_object_operations::do_object_unlock.
+ *
+ * Used to release LDLM lock(s).
+ *
+ * \see dt_object_operations::do_object_unlock() in the API description
+ * for details.
+ */
 static int lod_object_unlock(const struct lu_env *env, struct dt_object *dt,
                             struct ldlm_enqueue_info *einfo,
                             union ldlm_policy_data *policy)
@@ -3165,10 +3924,6 @@ static int lod_object_unlock(const struct lu_env *env, struct dt_object *dt,
        if (!S_ISDIR(dt->do_lu.lo_header->loh_attr))
                RETURN(-ENOTDIR);
 
-       rc = lod_load_striping(env, lo);
-       if (rc != 0)
-               RETURN(rc);
-
        /* Note: for remote lock for single stripe dir, MDT will cancel
         * the lock by lockh directly */
        if (lo->ldo_stripenr <= 1 && dt_object_remote(dt_object_child(dt)))
@@ -3185,6 +3940,14 @@ static int lod_object_unlock(const struct lu_env *env, struct dt_object *dt,
        RETURN(rc);
 }
 
+/**
+ * Implementation of dt_object_operations::do_object_lock.
+ *
+ * Used to get LDLM lock on the non-striped and striped objects.
+ *
+ * \see dt_object_operations::do_object_lock() in the API description
+ * for details.
+ */
 static int lod_object_lock(const struct lu_env *env,
                           struct dt_object *dt,
                           struct lustre_handle *lh,
@@ -3234,9 +3997,28 @@ static int lod_object_lock(const struct lu_env *env,
                                       res_id);
                einfo->ei_res_id = res_id;
 
-               LASSERT(lo->ldo_stripe[i]);
-               rc = dt_object_lock(env, lo->ldo_stripe[i], &lockh, einfo,
-                                   policy);
+               LASSERT(lo->ldo_stripe[i] != NULL);
+               if (likely(dt_object_remote(lo->ldo_stripe[i]))) {
+                       rc = dt_object_lock(env, lo->ldo_stripe[i], &lockh,
+                                           einfo, policy);
+               } else {
+                       struct ldlm_namespace *ns = einfo->ei_namespace;
+                       ldlm_blocking_callback blocking = einfo->ei_cb_local_bl;
+                       ldlm_completion_callback completion = einfo->ei_cb_cp;
+                       __u64   dlmflags = LDLM_FL_ATOMIC_CB;
+
+                       /* This only happens if there are mulitple stripes
+                        * on the master MDT, i.e. except stripe0, there are
+                        * other stripes on the Master MDT as well, Only
+                        * happens in the test case right now. */
+                       LASSERT(ns != NULL);
+                       rc = ldlm_cli_enqueue_local(ns, res_id, LDLM_IBITS,
+                                                   policy, einfo->ei_mode,
+                                                   &dlmflags, blocking,
+                                                   completion, NULL,
+                                                   NULL, 0, LVB_T_NONE,
+                                                   NULL, &lockh);
+               }
                if (rc != 0)
                        GOTO(out, rc);
                slave_locks->lsl_handle[i] = lockh;
@@ -3280,36 +4062,67 @@ struct dt_object_operations lod_obj_ops = {
        .do_ref_add             = lod_ref_add,
        .do_declare_ref_del     = lod_declare_ref_del,
        .do_ref_del             = lod_ref_del,
-       .do_capa_get            = lod_capa_get,
        .do_object_sync         = lod_object_sync,
        .do_object_lock         = lod_object_lock,
        .do_object_unlock       = lod_object_unlock,
 };
 
+/**
+ * Implementation of dt_body_operations::dbo_read.
+ *
+ * \see dt_body_operations::dbo_read() in the API description for details.
+ */
 static ssize_t lod_read(const struct lu_env *env, struct dt_object *dt,
-                       struct lu_buf *buf, loff_t *pos,
-                       struct lustre_capa *capa)
+                       struct lu_buf *buf, loff_t *pos)
 {
        struct dt_object *next = dt_object_child(dt);
-        return next->do_body_ops->dbo_read(env, next, buf, pos, capa);
+       return next->do_body_ops->dbo_read(env, next, buf, pos);
 }
 
+/**
+ * Implementation of dt_body_operations::dbo_declare_write.
+ *
+ * \see dt_body_operations::dbo_declare_write() in the API description
+ * for details.
+ */
 static ssize_t lod_declare_write(const struct lu_env *env,
                                 struct dt_object *dt,
                                 const struct lu_buf *buf, loff_t pos,
                                 struct thandle *th)
 {
-       return dt_declare_record_write(env, dt_object_child(dt),
-                                      buf, pos, th);
+       return lod_sub_object_declare_write(env, dt_object_child(dt), buf, pos,
+                                           th);
 }
 
+/**
+ * Implementation of dt_body_operations::dbo_write.
+ *
+ * \see dt_body_operations::dbo_write() in the API description for details.
+ */
 static ssize_t lod_write(const struct lu_env *env, struct dt_object *dt,
                         const struct lu_buf *buf, loff_t *pos,
-                        struct thandle *th, struct lustre_capa *capa, int iq)
+                        struct thandle *th, int iq)
 {
-       struct dt_object *next = dt_object_child(dt);
-       LASSERT(next);
-       return next->do_body_ops->dbo_write(env, next, buf, pos, th, capa, iq);
+       return lod_sub_object_write(env, dt_object_child(dt), buf, pos, th, iq);
+}
+
+static int lod_declare_punch(const struct lu_env *env, struct dt_object *dt,
+                            __u64 start, __u64 end, struct thandle *th)
+{
+       if (dt_object_remote(dt))
+               return -ENOTSUPP;
+
+       return lod_sub_object_declare_punch(env, dt_object_child(dt), start,
+                                           end, th);
+}
+
+static int lod_punch(const struct lu_env *env, struct dt_object *dt,
+                    __u64 start, __u64 end, struct thandle *th)
+{
+       if (dt_object_remote(dt))
+               return -ENOTSUPP;
+
+       return lod_sub_object_punch(env, dt_object_child(dt), start, end, th);
 }
 
 static const struct dt_body_operations lod_body_lnk_ops = {
@@ -3318,6 +4131,25 @@ static const struct dt_body_operations lod_body_lnk_ops = {
        .dbo_write              = lod_write
 };
 
+static const struct dt_body_operations lod_body_ops = {
+       .dbo_read               = lod_read,
+       .dbo_declare_write      = lod_declare_write,
+       .dbo_write              = lod_write,
+       .dbo_declare_punch      = lod_declare_punch,
+       .dbo_punch              = lod_punch,
+};
+
+/**
+ * Implementation of lu_object_operations::loo_object_init.
+ *
+ * The function determines the type and the index of the target device using
+ * sequence of the object's FID. Then passes control down to the
+ * corresponding device:
+ *  OSD for the local objects, OSP for remote
+ *
+ * \see lu_object_operations::loo_object_init() in the API description
+ * for details.
+ */
 static int lod_object_init(const struct lu_env *env, struct lu_object *lo,
                           const struct lu_object_conf *conf)
 {
@@ -3326,14 +4158,22 @@ static int lod_object_init(const struct lu_env *env, struct lu_object *lo,
        struct lu_object        *cobj;
        struct lod_tgt_descs    *ltd    = NULL;
        struct lod_tgt_desc     *tgt;
-       mdsno_t                  idx    = 0;
+       u32                      idx    = 0;
        int                      type   = LU_SEQ_RANGE_ANY;
        int                      rc;
        ENTRY;
 
        rc = lod_fld_lookup(env, lod, lu_object_fid(lo), &idx, &type);
-       if (rc != 0)
+       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;
+
                RETURN(rc);
+       }
 
        if (type == LU_SEQ_RANGE_MDT &&
            idx == lu_site2seq(lo->lo_dev->ld_site)->ss_node_id) {
@@ -3373,6 +4213,16 @@ static int lod_object_init(const struct lu_env *env, struct lu_object *lo,
        RETURN(0);
 }
 
+/**
+ *
+ * Release resources associated with striping.
+ *
+ * If the object is striped (regular or directory), then release
+ * the stripe objects references and free the ldo_stripe array.
+ *
+ * \param[in] env      execution environment
+ * \param[in] lo       object
+ */
 void lod_object_free_striping(const struct lu_env *env, struct lod_object *lo)
 {
        int i;
@@ -3395,21 +4245,38 @@ void lod_object_free_striping(const struct lu_env *env, struct lod_object *lo)
                lo->ldo_stripe = NULL;
                lo->ldo_stripes_allocated = 0;
        }
+       lo->ldo_striping_cached = 0;
        lo->ldo_stripenr = 0;
        lo->ldo_pattern = 0;
 }
 
-/*
- * ->start is called once all slices are initialized, including header's
- * cache for mode (object type). using the type we can initialize ops
+/**
+ * Implementation of lu_object_operations::loo_object_start.
+ *
+ * \see lu_object_operations::loo_object_start() in the API description
+ * for details.
  */
 static int lod_object_start(const struct lu_env *env, struct lu_object *o)
 {
-       if (S_ISLNK(o->lo_header->loh_attr & S_IFMT))
+       if (S_ISLNK(o->lo_header->loh_attr & S_IFMT)) {
                lu2lod_obj(o)->ldo_obj.do_body_ops = &lod_body_lnk_ops;
+       } else if (S_ISREG(o->lo_header->loh_attr & S_IFMT) ||
+                  fid_is_local_file(lu_object_fid(o))) {
+               /* Note: some local file (like last rcvd) is created
+                * through bottom layer (OSD), so the object initialization
+                * comes to lod, it does not set loh_attr yet, so
+                * set do_body_ops for local file anyway */
+               lu2lod_obj(o)->ldo_obj.do_body_ops = &lod_body_ops;
+       }
        return 0;
 }
 
+/**
+ * Implementation of lu_object_operations::loo_object_free.
+ *
+ * \see lu_object_operations::loo_object_free() in the API description
+ * for details.
+ */
 static void lod_object_free(const struct lu_env *env, struct lu_object *o)
 {
        struct lod_object *mo = lu2lod_obj(o);
@@ -3426,12 +4293,24 @@ static void lod_object_free(const struct lu_env *env, struct lu_object *o)
        OBD_SLAB_FREE_PTR(mo, lod_object_kmem);
 }
 
+/**
+ * Implementation of lu_object_operations::loo_object_release.
+ *
+ * \see lu_object_operations::loo_object_release() in the API description
+ * for details.
+ */
 static void lod_object_release(const struct lu_env *env, struct lu_object *o)
 {
        /* XXX: shouldn't we release everything here in case if object
         * creation failed before? */
 }
 
+/**
+ * Implementation of lu_object_operations::loo_object_print.
+ *
+ * \see lu_object_operations::loo_object_print() in the API description
+ * for details.
+ */
 static int lod_object_print(const struct lu_env *env, void *cookie,
                            lu_printer_t p, const struct lu_object *l)
 {