/*
 * GPL HEADER START
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * 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 LICENSE file that accompanied this code).
 *
 * You should have received a copy of the GNU General Public License
 * version 2 along with this program; If not, see
 * http://www.gnu.org/licenses/gpl-2.0.html
 *
 * GPL HEADER END
 */
/*
 * Copyright (c) 2013, Intel Corporation.
 */
/*
 * lustre/osp/osp_md_object.c
 *
 * OST/MDT proxy device (OSP) Metadata methods
 *
 * This file implements methods for remote MD object, which include
 * dt_object_operations, dt_index_operations and dt_body_operations.
 *
 * If there are multiple MDTs in one filesystem, one operation might
 * include modifications in several MDTs. In such cases, clients
 * send the RPC to the master MDT, then the operation is decomposed into
 * object updates which will be dispatched to OSD or OSP. The local updates
 * go to local OSD and the remote updates go to OSP. In OSP, these remote
 * object updates will be packed into an update RPC, sent to the remote MDT
 * and handled by Object Update Target (OUT).
 *
 * In DNE phase I, because of missing complete recovery solution, updates
 * will be executed in order and synchronously.
 *     1. The transaction is created.
 *     2. In transaction declare, it collects and packs remote
 *        updates (in osp_md_declare_xxx()).
 *     3. In transaction start, it sends these remote updates
 *        to remote MDTs, which will execute these updates synchronously.
 *     4. In transaction execute phase, the local updates will be executed
 *        synchronously.
 *
 * Author: Di Wang <di.wang@intel.com>
 */

#define DEBUG_SUBSYSTEM S_MDS

#include <lustre_log.h>
#include "osp_internal.h"

static const char dot[] = ".";
static const char dotdot[] = "..";

/**
 * Implementation of dt_object_operations::do_declare_create
 *
 * Insert object create update into the RPC, which will be sent during
 * transaction start. Note: if the object has already been created,
 * we must add object destroy updates ahead of create updates, so it will
 * destroy then recreate the object.
 *
 * \param[in] env	execution environment
 * \param[in] dt	remote object to be created
 * \param[in] attr	attribute of the created object
 * \param[in] hint	creation hint
 * \param[in] dof	creation format information
 * \param[in] th	the transaction handle
 *
 * \retval		0 if the insertion succeeds.
 * \retval		negative errno if the insertion fails.
 */
int osp_md_declare_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_update_request	*update;
	int				rc;

	update = dt_update_request_find_or_create(th, dt);
	if (IS_ERR(update)) {
		CERROR("%s: Get OSP update buf failed: rc = %d\n",
		       dt->do_lu.lo_dev->ld_obd->obd_name,
		       (int)PTR_ERR(update));
		return PTR_ERR(update);
	}

	if (lu_object_exists(&dt->do_lu)) {
		/* If the object already exists, we needs to destroy
		 * this orphan object first.
		 *
		 * The scenario might happen in this case
		 *
		 * 1. client send remote create to MDT0.
		 * 2. MDT0 send create update to MDT1.
		 * 3. MDT1 finished create synchronously.
		 * 4. MDT0 failed and reboot.
		 * 5. client resend remote create to MDT0.
		 * 6. MDT0 tries to resend create update to MDT1,
		 *    but find the object already exists
		 */
		CDEBUG(D_HA, "%s: object "DFID" exists, destroy this orphan\n",
		       dt->do_lu.lo_dev->ld_obd->obd_name,
		       PFID(lu_object_fid(&dt->do_lu)));

		rc = out_ref_del_pack(env, &update->dur_buf,
				      lu_object_fid(&dt->do_lu),
				      update->dur_batchid);
		if (rc != 0)
			GOTO(out, rc);

		if (S_ISDIR(lu_object_attr(&dt->do_lu))) {
			/* decrease for ".." */
			rc = out_ref_del_pack(env, &update->dur_buf,
					      lu_object_fid(&dt->do_lu),
					      update->dur_batchid);
			if (rc != 0)
				GOTO(out, rc);
		}

		rc = out_object_destroy_pack(env, &update->dur_buf,
					     lu_object_fid(&dt->do_lu),
					     update->dur_batchid);
		if (rc != 0)
			GOTO(out, rc);

		dt->do_lu.lo_header->loh_attr &= ~LOHA_EXISTS;
		/* Increase batchid to add this orphan object deletion
		 * to separate transaction */
		update_inc_batchid(update);
	}

	rc = out_create_pack(env, &update->dur_buf,
			     lu_object_fid(&dt->do_lu), attr, hint, dof,
			     update->dur_batchid);
	if (rc != 0)
		GOTO(out, rc);
out:
	if (rc)
		CERROR("%s: Insert update error: rc = %d\n",
		       dt->do_lu.lo_dev->ld_obd->obd_name, rc);

	return rc;
}

/**
 * Implementation of dt_object_operations::do_create
 *
 * It sets necessary flags for created object. In DNE phase I,
 * remote updates are actually executed during transaction start,
 * i.e. the object has already been created when calling this method.
 *
 * \param[in] env	execution environment
 * \param[in] dt	object to be created
 * \param[in] attr	attribute of the created object
 * \param[in] hint	creation hint
 * \param[in] dof	creation format information
 * \param[in] th	the transaction handle
 *
 * \retval		only return 0 for now
 */
int osp_md_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)
{
	CDEBUG(D_INFO, "create object "DFID"\n",
	       PFID(&dt->do_lu.lo_header->loh_fid));

	/* Because the create update RPC will be sent during declare phase,
	 * if creation reaches here, it means the object has been created
	 * successfully */
	dt->do_lu.lo_header->loh_attr |= LOHA_EXISTS | (attr->la_mode & S_IFMT);
	dt2osp_obj(dt)->opo_non_exist = 0;

	return 0;
}

/**
 * Implementation of dt_object_operations::do_declare_ref_del
 *
 * Declare decreasing the reference count of the remote object, i.e. insert
 * decreasing object reference count update into the RPC, which will be sent
 * during transaction start.
 *
 * \param[in] env	execution environment
 * \param[in] dt	object to decrease the reference count.
 * \param[in] th	the transaction handle of refcount decrease.
 *
 * \retval		0 if the insertion succeeds.
 * \retval		negative errno if the insertion fails.
 */
static int osp_md_declare_object_ref_del(const struct lu_env *env,
					 struct dt_object *dt,
					 struct thandle *th)
{
	struct dt_update_request	*update;
	int				rc;

	update = dt_update_request_find_or_create(th, dt);
	if (IS_ERR(update)) {
		CERROR("%s: Get OSP update buf failed: rc = %d\n",
		       dt->do_lu.lo_dev->ld_obd->obd_name,
		      (int)PTR_ERR(update));
		return PTR_ERR(update);
	}

	rc = out_ref_del_pack(env, &update->dur_buf,
			      lu_object_fid(&dt->do_lu),
			      update->dur_batchid);
	return rc;
}

/**
 * Implementation of dt_object_operations::do_ref_del
 *
 * Do nothing in this method for now. In DNE phase I, remote updates are
 * actually executed during transaction start, i.e. the object reference
 * count has already been decreased when calling this method.
 *
 * \param[in] env	execution environment
 * \param[in] dt	object to decrease the reference count
 * \param[in] th	the transaction handle
 *
 * \retval		only return 0 for now
 */
static int osp_md_object_ref_del(const struct lu_env *env,
				 struct dt_object *dt,
				 struct thandle *th)
{
	CDEBUG(D_INFO, "ref del object "DFID"\n",
	       PFID(&dt->do_lu.lo_header->loh_fid));

	return 0;
}

/**
 * Implementation of dt_object_operations::do_declare_ref_del
 *
 * Declare increasing the reference count of the remote object,
 * i.e. insert increasing object reference count update into RPC.
 *
 * \param[in] env	execution environment
 * \param[in] dt	object on which to increase the reference count.
 * \param[in] th	the transaction handle.
 *
 * \retval		0 if the insertion succeeds.
 * \retval		negative errno if the insertion fails.
 */
static int osp_md_declare_ref_add(const struct lu_env *env,
				  struct dt_object *dt, struct thandle *th)
{
	struct dt_update_request	*update;
	int				rc;

	update = dt_update_request_find_or_create(th, dt);
	if (IS_ERR(update)) {
		CERROR("%s: Get OSP update buf failed: rc = %d\n",
		       dt->do_lu.lo_dev->ld_obd->obd_name,
		       (int)PTR_ERR(update));
		return PTR_ERR(update);
	}

	rc = out_ref_add_pack(env, &update->dur_buf,
			      lu_object_fid(&dt->do_lu),
			      update->dur_batchid);

	return rc;
}

/**
 * Implementation of dt_object_operations::do_ref_add
 *
 * Do nothing in this method for now. In DNE phase I, remote updates are
 * actually executed during transaction start, i.e. the object reference
 * count has already been increased when calling this method.
 *
 * \param[in] env	execution environment
 * \param[in] dt	object on which to increase the reference count
 * \param[in] th	the transaction handle
 *
 * \retval		only return 0 for now
 */
static int osp_md_object_ref_add(const struct lu_env *env, struct dt_object *dt,
				 struct thandle *th)
{
	CDEBUG(D_INFO, "ref add object "DFID"\n",
	       PFID(&dt->do_lu.lo_header->loh_fid));

	return 0;
}

/**
 * Implementation of dt_object_operations::do_ah_init
 *
 * Initialize the allocation hint for object creation, which is usually called
 * before the creation, and these hints (parent and child mode) will be sent to
 * the remote Object Update Target (OUT) and used in the object create process,
 * same as OSD object creation.
 *
 * \param[in] env	execution environment
 * \param[in] ah	the hint to be initialized
 * \param[in] parent	the parent of the object
 * \param[in] child	the object to be created
 * \param[in] child_mode the mode of the created object
 */
static void osp_md_ah_init(const struct lu_env *env,
			   struct dt_allocation_hint *ah,
			   struct dt_object *parent,
			   struct dt_object *child,
			   umode_t child_mode)
{
	LASSERT(ah);

	ah->dah_parent = parent;
	ah->dah_mode = child_mode;
}

/**
 * Add attr_set sub-request into the OUT RPC.
 *
 * \param[in] env	execution environment
 * \param[in] dt	object on which to set attributes
 * \param[in] attr	attributes to be set
 * \param[in] th	the transaction handle
 *
 * \retval		0 if the insertion succeeds.
 * \retval		negative errno if the insertion fails.
 */
int __osp_md_attr_set(const struct lu_env *env, struct dt_object *dt,
		      const struct lu_attr *attr, struct thandle *th)
{
	struct dt_update_request	*update;
	int				rc;

	update = dt_update_request_find_or_create(th, dt);
	if (IS_ERR(update)) {
		CERROR("%s: Get OSP update buf failed: %d\n",
		       dt->do_lu.lo_dev->ld_obd->obd_name,
		       (int)PTR_ERR(update));
		return PTR_ERR(update);
	}

	rc = out_attr_set_pack(env, &update->dur_buf,
			       lu_object_fid(&dt->do_lu), attr,
			       update->dur_batchid);

	return rc;
}

/**
 * Implementation of dt_object_operations::do_declare_attr_get
 *
 * Declare setting attributes to the specified remote object.
 *
 * If the transaction is a remote transaction, then add the modification
 * sub-request into the OUT RPC here, and such OUT RPC will be triggered
 * when transaction start.
 *
 * \param[in] env	execution environment
 * \param[in] dt	object on which to set attributes
 * \param[in] attr	attributes to be set
 * \param[in] th	the transaction handle
 *
 * \retval		0 if the insertion succeeds.
 * \retval		negative errno if the insertion fails.
 */
int osp_md_declare_attr_set(const struct lu_env *env, struct dt_object *dt,
			    const struct lu_attr *attr, struct thandle *th)
{
	int rc = 0;

	CDEBUG(D_INFO, "declare attr set object "DFID"\n",
	       PFID(&dt->do_lu.lo_header->loh_fid));

	if (!is_only_remote_trans(th))
		rc = __osp_md_attr_set(env, dt, attr, th);

	return rc;
}

/**
 * Implementation of dt_object_operations::do_attr_set
 *
 * Set attributes to the specified remote object.
 *
 * If the transaction is a remote transaction, then related modification
 * sub-request has been added in the declare phase and related OUT RPC
 * has been triggered at transaction start. Otherwise, the modification
 * sub-request will be added here, and related OUT RPC will be triggered
 * when transaction stop.
 *
 * \param[in] env	execution environment
 * \param[in] dt	object to set attributes
 * \param[in] attr	attributes to be set
 * \param[in] th	the transaction handle
 * \param[in] capa	capability of setting attributes (not yet implemented).
 *
 * \retval		only return 0 for now
 */
int osp_md_attr_set(const struct lu_env *env, struct dt_object *dt,
		    const struct lu_attr *attr, struct thandle *th,
		    struct lustre_capa *capa)
{
	int rc = 0;

	CDEBUG(D_INFO, "attr set object "DFID"\n",
	       PFID(&dt->do_lu.lo_header->loh_fid));

	if (is_only_remote_trans(th))
		rc = __osp_md_attr_set(env, dt, attr, th);

	RETURN(rc);
}

/**
 * Implementation of dt_object_operations::do_read_lock
 *
 * osp_md_object_{read,write}_lock() will only lock the remote object in the
 * local cache, which uses the semaphore (opo_sem) inside the osp_object to
 * lock the object. Note: it will not lock the object in the whole cluster,
 * which relies on the LDLM lock.
 *
 * \param[in] env	execution environment
 * \param[in] dt	object to be locked
 * \param[in] role	lock role from MDD layer, see mdd_object_role().
 */
static void osp_md_object_read_lock(const struct lu_env *env,
				    struct dt_object *dt, unsigned role)
{
	struct osp_object  *obj = dt2osp_obj(dt);

	LASSERT(obj->opo_owner != env);
	down_read_nested(&obj->opo_sem, role);

	LASSERT(obj->opo_owner == NULL);
}

/**
 * Implementation of dt_object_operations::do_write_lock
 *
 * Lock the remote object in write mode.
 *
 * \param[in] env	execution environment
 * \param[in] dt	object to be locked
 * \param[in] role	lock role from MDD layer, see mdd_object_role().
 */
static void osp_md_object_write_lock(const struct lu_env *env,
				     struct dt_object *dt, unsigned role)
{
	struct osp_object *obj = dt2osp_obj(dt);

	down_write_nested(&obj->opo_sem, role);

	LASSERT(obj->opo_owner == NULL);
	obj->opo_owner = env;
}

/**
 * Implementation of dt_object_operations::do_read_unlock
 *
 * Unlock the read lock of remote object.
 *
 * \param[in] env	execution environment
 * \param[in] dt	object to be unlocked
 */
static void osp_md_object_read_unlock(const struct lu_env *env,
				      struct dt_object *dt)
{
	struct osp_object *obj = dt2osp_obj(dt);

	up_read(&obj->opo_sem);
}

/**
 * Implementation of dt_object_operations::do_write_unlock
 *
 * Unlock the write lock of remote object.
 *
 * \param[in] env	execution environment
 * \param[in] dt	object to be unlocked
 */
static void osp_md_object_write_unlock(const struct lu_env *env,
				       struct dt_object *dt)
{
	struct osp_object *obj = dt2osp_obj(dt);

	LASSERT(obj->opo_owner == env);
	obj->opo_owner = NULL;
	up_write(&obj->opo_sem);
}

/**
 * Implementation of dt_object_operations::do_write_locked
 *
 * Test if the object is locked in write mode.
 *
 * \param[in] env	execution environment
 * \param[in] dt	object to be tested
 */
static int osp_md_object_write_locked(const struct lu_env *env,
				      struct dt_object *dt)
{
	struct osp_object *obj = dt2osp_obj(dt);

	return obj->opo_owner == env;
}

/**
 * Implementation of dt_index_operations::dio_lookup
 *
 * Look up record by key under a remote index object. It packs lookup update
 * into RPC, sends to the remote OUT and waits for the lookup result.
 *
 * \param[in] env	execution environment
 * \param[in] dt	index object to lookup
 * \param[out] rec	record in which to return lookup result
 * \param[in] key	key of index which will be looked up
 * \param[in] capa	capability of lookup (not yet implemented)
 *
 * \retval		1 if the lookup succeeds.
 * \retval              negative errno if the lookup fails.
 */
static int osp_md_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 lu_buf		*lbuf	= &osp_env_info(env)->osi_lb2;
	struct osp_device	*osp	= lu2osp_dev(dt->do_lu.lo_dev);
	struct dt_device	*dt_dev	= &osp->opd_dt_dev;
	struct dt_update_request   *update;
	struct object_update_reply *reply;
	struct ptlrpc_request	   *req = NULL;
	struct lu_fid		   *fid;
	int			   rc;
	ENTRY;

	/* Because it needs send the update buffer right away,
	 * just create an update buffer, instead of attaching the
	 * update_remote list of the thandle.
	 */
	update = dt_update_request_create(dt_dev);
	if (IS_ERR(update))
		RETURN(PTR_ERR(update));

	rc = out_index_lookup_pack(env, &update->dur_buf,
				   lu_object_fid(&dt->do_lu), rec, key);
	if (rc != 0) {
		CERROR("%s: Insert update error: rc = %d\n",
		       dt_dev->dd_lu_dev.ld_obd->obd_name, rc);
		GOTO(out, rc);
	}

	rc = out_remote_sync(env, osp->opd_obd->u.cli.cl_import, update, &req);
	if (rc < 0)
		GOTO(out, rc);

	reply = req_capsule_server_sized_get(&req->rq_pill,
					     &RMF_OUT_UPDATE_REPLY,
					     OUT_UPDATE_REPLY_SIZE);
	if (reply->ourp_magic != UPDATE_REPLY_MAGIC) {
		CERROR("%s: Wrong version %x expected %x: rc = %d\n",
		       dt_dev->dd_lu_dev.ld_obd->obd_name,
		       reply->ourp_magic, UPDATE_REPLY_MAGIC, -EPROTO);
		GOTO(out, rc = -EPROTO);
	}

	rc = object_update_result_data_get(reply, lbuf, 0);
	if (rc < 0)
		GOTO(out, rc);

	if (lbuf->lb_len != sizeof(*fid)) {
		CERROR("%s: lookup "DFID" %s wrong size %d\n",
		       dt_dev->dd_lu_dev.ld_obd->obd_name,
		       PFID(lu_object_fid(&dt->do_lu)), (char *)key,
		       (int)lbuf->lb_len);
		GOTO(out, rc = -EINVAL);
	}

	fid = lbuf->lb_buf;
	if (ptlrpc_rep_need_swab(req))
		lustre_swab_lu_fid(fid);
	if (!fid_is_sane(fid)) {
		CERROR("%s: lookup "DFID" %s invalid fid "DFID"\n",
		       dt_dev->dd_lu_dev.ld_obd->obd_name,
		       PFID(lu_object_fid(&dt->do_lu)), (char *)key, PFID(fid));
		GOTO(out, rc = -EINVAL);
	}

	memcpy(rec, fid, sizeof(*fid));

	GOTO(out, rc = 1);

out:
	if (req != NULL)
		ptlrpc_req_finished(req);

	dt_update_request_destroy(update);

	return rc;
}

/**
 * Implementation of dt_index_operations::dio_declare_insert
 *
 * Declare the index insert of the remote object, i.e. pack index insert update
 * into the RPC, which will be sent during transaction start.
 *
 * \param[in] env	execution environment
 * \param[in] dt	object for which to insert index
 * \param[in] rec	record of the index which will be inserted
 * \param[in] key	key of the index which will be inserted
 * \param[in] th	the transaction handle
 *
 * \retval		0 if the insertion succeeds.
 * \retval		negative errno if the insertion fails.
 */
static int osp_md_declare_insert(const struct lu_env *env,
				 struct dt_object *dt,
				 const struct dt_rec *rec,
				 const struct dt_key *key,
				 struct thandle *th)
{
	struct dt_update_request *update;
	int			 rc;

	update = dt_update_request_find_or_create(th, dt);
	if (IS_ERR(update)) {
		CERROR("%s: Get OSP update buf failed: rc = %d\n",
		       dt->do_lu.lo_dev->ld_obd->obd_name,
		       (int)PTR_ERR(update));
		return PTR_ERR(update);
	}

	rc = out_index_insert_pack(env, &update->dur_buf,
				   lu_object_fid(&dt->do_lu), rec, key,
				   update->dur_batchid);
	return rc;
}

/**
 * Implementation of dt_index_operations::dio_insert
 *
 * Do nothing in this method for now. In DNE phase I, remote updates
 * are actually executed during transaction start, i.e. the index has
 * already been inserted when calling this method.
 *
 * \param[in] env	execution environment
 * \param[in] dt	object for which to insert index
 * \param[in] rec	record of the index to be inserted
 * \param[in] key	key of the index to be inserted
 * \param[in] th	the transaction handle
 * \param[in] capa	capability of insert (not yet implemented)
 * \param[in] ignore_quota quota enforcement for insert
 *
 * \retval		only return 0 for now
 */
static int osp_md_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 ignore_quota)
{
	return 0;
}

/**
 * Implementation of dt_index_operations::dio_declare_delete
 *
 * Declare the index delete of the remote object, i.e. insert index delete
 * update into the RPC, which will be sent during transaction start.
 *
 * \param[in] env	execution environment
 * \param[in] dt	object for which to delete index
 * \param[in] key	key of the index
 * \param[in] th	the transaction handle
 *
 * \retval		0 if the insertion succeeds.
 * \retval		negative errno if the insertion fails.
 */
static int osp_md_declare_delete(const struct lu_env *env,
				 struct dt_object *dt,
				 const struct dt_key *key,
				 struct thandle *th)
{
	struct dt_update_request *update;
	int			 rc;

	update = dt_update_request_find_or_create(th, dt);
	if (IS_ERR(update)) {
		CERROR("%s: Get OSP update buf failed: rc = %d\n",
		       dt->do_lu.lo_dev->ld_obd->obd_name,
		       (int)PTR_ERR(update));
		return PTR_ERR(update);
	}

	rc = out_index_delete_pack(env, &update->dur_buf,
				   lu_object_fid(&dt->do_lu), key,
				   update->dur_batchid);
	return rc;
}

/**
 * Implementation of dt_index_operations::dio_delete
 *
 * Do nothing in this method for now. Because in DNE phase I, remote updates
 * are actually executed during transaction start, i.e. the index has already
 * been deleted when calling this method.
 *
 * \param[in] env	execution environment
 * \param[in] dt	object for which to delete index
 * \param[in] key	key of the index which will be deleted
 * \param[in] th	the transaction handle
 * \param[in] capa	capability of delete (not yet implemented)
 *
 * \retval		only return 0 for now
 */
static int osp_md_index_delete(const struct lu_env *env,
			       struct dt_object *dt,
			       const struct dt_key *key,
			       struct thandle *th,
			       struct lustre_capa *capa)
{
	CDEBUG(D_INFO, "index delete "DFID" %s\n",
	       PFID(&dt->do_lu.lo_header->loh_fid), (char *)key);

	return 0;
}

/**
 * Implementation of dt_index_operations::dio_it.next
 *
 * Advance the pointer of the iterator to the next entry. It shares a similar
 * internal implementation with osp_orphan_it_next(), which is being used for
 * remote orphan index object. This method will be used for remote directory.
 *
 * \param[in] env	execution environment
 * \param[in] di	iterator of this iteration
 *
 * \retval		0 if the pointer is advanced successfuly.
 * \retval		1 if it reaches to the end of the index object.
 * \retval		negative errno if the pointer cannot be advanced.
 */
int osp_md_index_it_next(const struct lu_env *env, struct dt_it *di)
{
	struct osp_it		*it = (struct osp_it *)di;
	struct lu_idxpage	*idxpage;
	struct lu_dirent	*ent = (struct lu_dirent *)it->ooi_ent;
	int			rc;
	ENTRY;

again:
	idxpage = it->ooi_cur_idxpage;
	if (idxpage != NULL) {
		if (idxpage->lip_nr == 0)
			RETURN(1);

		it->ooi_pos_ent++;
		if (ent == NULL) {
			it->ooi_ent =
			      (struct lu_dirent *)idxpage->lip_entries;
			RETURN(0);
		} else if (le16_to_cpu(ent->lde_reclen) != 0 &&
			   it->ooi_pos_ent < idxpage->lip_nr) {
			ent = (struct lu_dirent *)(((char *)ent) +
					le16_to_cpu(ent->lde_reclen));
			it->ooi_ent = ent;
			RETURN(0);
		} else {
			it->ooi_ent = NULL;
		}
	}

	rc = osp_it_next_page(env, di);
	if (rc == 0)
		goto again;

	RETURN(rc);
}

/**
 * Implementation of dt_index_operations::dio_it.key
 *
 * Get the key at current iterator poisiton. These iteration methods
 * (dio_it) will only be used for iterating the remote directory, so
 * the key is the name of the directory entry.
 *
 * \param[in] env	execution environment
 * \param[in] di	iterator of this iteration
 *
 * \retval		name of the current entry
 */
static struct dt_key *osp_it_key(const struct lu_env *env,
				 const struct dt_it *di)
{
	struct osp_it		*it = (struct osp_it *)di;
	struct lu_dirent	*ent = (struct lu_dirent *)it->ooi_ent;

	return (struct dt_key *)ent->lde_name;
}

/**
 * Implementation of dt_index_operations::dio_it.key_size
 *
 * Get the key size at current iterator poisiton. These iteration methods
 * (dio_it) will only be used for iterating the remote directory, so the key
 * size is the name size of the directory entry.
 *
 * \param[in] env	execution environment
 * \param[in] di	iterator of this iteration
 *
 * \retval		name size of the current entry
 */

static int osp_it_key_size(const struct lu_env *env, const struct dt_it *di)
{
	struct osp_it		*it = (struct osp_it *)di;
	struct lu_dirent	*ent = (struct lu_dirent *)it->ooi_ent;

	return (int)le16_to_cpu(ent->lde_namelen);
}

/**
 * Implementation of dt_index_operations::dio_it.rec
 *
 * Get the record at current iterator position. These iteration methods
 * (dio_it) will only be used for iterating the remote directory, so it
 * uses lu_dirent_calc_size() to calculate the record size.
 *
 * \param[in] env	execution environment
 * \param[in] di	iterator of this iteration
 * \param[out] rec	the record to be returned
 * \param[in] attr	attributes of the index object, so it knows
 *                      how to pack the entry.
 *
 * \retval		only return 0 for now
 */
static int osp_md_index_it_rec(const struct lu_env *env, const struct dt_it *di,
			       struct dt_rec *rec, __u32 attr)
{
	struct osp_it		*it = (struct osp_it *)di;
	struct lu_dirent	*ent = (struct lu_dirent *)it->ooi_ent;
	int			reclen;

	reclen = lu_dirent_calc_size(le16_to_cpu(ent->lde_namelen), attr);
	memcpy(rec, ent, reclen);
	return 0;
}

/**
 * Implementation of dt_index_operations::dio_it.load
 *
 * Locate the iteration cursor to the specified position (cookie).
 *
 * \param[in] env	pointer to the thread context
 * \param[in] di	pointer to the iteration structure
 * \param[in] hash	the specified position
 *
 * \retval		positive number for locating to the exactly position
 *			or the next
 * \retval		0 for arriving at the end of the iteration
 * \retval		negative error number on failure
 */
static int osp_it_load(const struct lu_env *env, const struct dt_it *di,
		       __u64 hash)
{
	struct osp_it	*it	= (struct osp_it *)di;
	int		 rc;

	it->ooi_next = hash;
	rc = osp_md_index_it_next(env, (struct dt_it *)di);
	if (rc == 1)
		return 0;

	if (rc == 0)
		return 1;

	return rc;
}

const struct dt_index_operations osp_md_index_ops = {
	.dio_lookup         = osp_md_index_lookup,
	.dio_declare_insert = osp_md_declare_insert,
	.dio_insert         = osp_md_index_insert,
	.dio_declare_delete = osp_md_declare_delete,
	.dio_delete         = osp_md_index_delete,
	.dio_it     = {
		.init     = osp_it_init,
		.fini     = osp_it_fini,
		.get      = osp_it_get,
		.put      = osp_it_put,
		.next     = osp_md_index_it_next,
		.key      = osp_it_key,
		.key_size = osp_it_key_size,
		.rec      = osp_md_index_it_rec,
		.store    = osp_it_store,
		.load     = osp_it_load,
		.key_rec  = osp_it_key_rec,
	}
};

/**
 * Implementation of dt_object_operations::do_index_try
 *
 * Try to initialize the index API pointer for the given object. This
 * is the entry point of the index API, i.e. we must call this method
 * to initialize the index object before calling other index methods.
 *
 * \param[in] env	execution environment
 * \param[in] dt	index object to be initialized
 * \param[in] feat	the index feature of the object
 *
 * \retval		0 if the initialization succeeds.
 * \retval              negative errno if the initialization fails.
 */
static int osp_md_index_try(const struct lu_env *env,
			    struct dt_object *dt,
			    const struct dt_index_features *feat)
{
	dt->do_index_ops = &osp_md_index_ops;
	return 0;
}

/**
 * Implementation of dt_object_operations::do_object_lock
 *
 * Enqueue a lock (by ldlm_cli_enqueue()) of remote object on the remote MDT,
 * which will lock the object in the global namespace.
 *
 * \param[in] env	execution environment
 * \param[in] dt	object to be locked
 * \param[out] lh	lock handle
 * \param[in] einfo	enqueue information
 * \param[in] policy	lock policy
 *
 * \retval		ELDLM_OK if locking the object succeeds.
 * \retval		negative errno if locking fails.
 */
static int osp_md_object_lock(const struct lu_env *env,
			      struct dt_object *dt,
			      struct lustre_handle *lh,
			      struct ldlm_enqueue_info *einfo,
			      ldlm_policy_data_t *policy)
{
	struct ldlm_res_id	*res_id;
	struct dt_device	*dt_dev = lu2dt_dev(dt->do_lu.lo_dev);
	struct osp_device	*osp = dt2osp_dev(dt_dev);
	struct ptlrpc_request	*req;
	int			rc = 0;
	__u64			flags = 0;
	ldlm_mode_t		mode;

	res_id = einfo->ei_res_id;
	LASSERT(res_id != NULL);

	mode = ldlm_lock_match(osp->opd_obd->obd_namespace,
			       LDLM_FL_BLOCK_GRANTED, res_id,
			       einfo->ei_type, policy,
			       einfo->ei_mode, lh, 0);
	if (mode > 0)
		return ELDLM_OK;

	req = ldlm_enqueue_pack(osp->opd_exp, 0);
	if (IS_ERR(req))
		RETURN(PTR_ERR(req));

	rc = ldlm_cli_enqueue(osp->opd_exp, &req, einfo, res_id,
			      (const ldlm_policy_data_t *)policy,
			      &flags, NULL, 0, LVB_T_NONE, lh, 0);

	ptlrpc_req_finished(req);

	return rc == ELDLM_OK ? 0 : -EIO;
}

/**
 * Implementation of dt_object_operations::do_object_unlock
 *
 * Cancel a lock of a remote object.
 *
 * \param[in] env	execution environment
 * \param[in] dt	object to be unlocked
 * \param[in] einfo	lock enqueue information
 * \param[in] policy	lock policy
 *
 * \retval		Only return 0 for now.
 */
static int osp_md_object_unlock(const struct lu_env *env,
				struct dt_object *dt,
				struct ldlm_enqueue_info *einfo,
				ldlm_policy_data_t *policy)
{
	struct lustre_handle	*lockh = einfo->ei_cbdata;

	/* unlock finally */
	ldlm_lock_decref(lockh, einfo->ei_mode);

	return 0;
}

struct dt_object_operations osp_md_obj_ops = {
	.do_read_lock         = osp_md_object_read_lock,
	.do_write_lock        = osp_md_object_write_lock,
	.do_read_unlock       = osp_md_object_read_unlock,
	.do_write_unlock      = osp_md_object_write_unlock,
	.do_write_locked      = osp_md_object_write_locked,
	.do_declare_create    = osp_md_declare_object_create,
	.do_create            = osp_md_object_create,
	.do_declare_ref_add   = osp_md_declare_ref_add,
	.do_ref_add           = osp_md_object_ref_add,
	.do_declare_ref_del   = osp_md_declare_object_ref_del,
	.do_ref_del           = osp_md_object_ref_del,
	.do_declare_destroy   = osp_declare_object_destroy,
	.do_destroy           = osp_object_destroy,
	.do_ah_init           = osp_md_ah_init,
	.do_attr_get	      = osp_attr_get,
	.do_declare_attr_set  = osp_md_declare_attr_set,
	.do_attr_set          = osp_md_attr_set,
	.do_xattr_get         = osp_xattr_get,
	.do_declare_xattr_set = osp_declare_xattr_set,
	.do_xattr_set         = osp_xattr_set,
	.do_declare_xattr_del = osp_declare_xattr_del,
	.do_xattr_del         = osp_xattr_del,
	.do_index_try         = osp_md_index_try,
	.do_object_lock       = osp_md_object_lock,
	.do_object_unlock     = osp_md_object_unlock,
};

/**
 * Implementation of dt_body_operations::dbo_declare_write
 *
 * Declare an object write. In DNE phase I, it will pack the write
 * object update into the RPC.
 *
 * \param[in] env	execution environment
 * \param[in] dt	object to be written
 * \param[in] buf	buffer to write which includes an embedded size field
 * \param[in] pos	offet in the object to start writing at
 * \param[in] th	transaction handle
 *
 * \retval		0 if the insertion succeeds.
 * \retval		negative errno if the insertion fails.
 */
static ssize_t osp_md_declare_write(const struct lu_env *env,
				    struct dt_object *dt,
				    const struct lu_buf *buf,
				    loff_t pos, struct thandle *th)
{
	struct dt_update_request  *update;
	ssize_t			  rc;

	update = dt_update_request_find_or_create(th, dt);
	if (IS_ERR(update)) {
		CERROR("%s: Get OSP update buf failed: rc = %d\n",
		       dt->do_lu.lo_dev->ld_obd->obd_name,
		       (int)PTR_ERR(update));
		return PTR_ERR(update);
	}

	rc = out_write_pack(env, &update->dur_buf, lu_object_fid(&dt->do_lu),
			    buf, pos, update->dur_batchid);

	return rc;

}

/**
 * Implementation of dt_body_operations::dbo_write
 *
 * Return the buffer size. In DNE phase I, remote updates
 * are actually executed during transaction start, the buffer has
 * already been written when this method is being called.
 *
 * \param[in] env	execution environment
 * \param[in] dt	object to be written
 * \param[in] buf	buffer to write which includes an embedded size field
 * \param[in] pos	offet in the object to start writing at
 * \param[in] th	transaction handle
 * \param[in] capa	capability of the write (not yet implemented)
 * \param[in] ignore_quota quota enforcement for this write
 *
 * \retval		the buffer size in bytes.
 */
static ssize_t osp_md_write(const struct lu_env *env, struct dt_object *dt,
			    const struct lu_buf *buf, loff_t *pos,
			    struct thandle *handle,
			    struct lustre_capa *capa, int ignore_quota)
{
	*pos += buf->lb_len;
	return buf->lb_len;
}

/* These body operation will be used to write symlinks during migration etc */
struct dt_body_operations osp_md_body_ops = {
	.dbo_declare_write	= osp_md_declare_write,
	.dbo_write		= osp_md_write,
};