/*
 * 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.sun.com/software/products/lustre/docs/GPLv2.pdf
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 *
 * GPL HEADER END
 */
/*
 * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2011, 2012, Intel Corporation.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 *
 * lustre/obdclass/dt_object.c
 *
 * Dt Object.
 * Generic functions from dt_object.h
 *
 * Author: Nikita Danilov <nikita@clusterfs.com>
 */

#define DEBUG_SUBSYSTEM S_CLASS

#include <obd.h>
#include <dt_object.h>
#include <linux/list.h>
/* fid_be_to_cpu() */
#include <lustre_fid.h>

#include <lustre_quota.h>

/* context key constructor/destructor: dt_global_key_init, dt_global_key_fini */
LU_KEY_INIT(dt_global, struct dt_thread_info);
LU_KEY_FINI(dt_global, struct dt_thread_info);

struct lu_context_key dt_key = {
	.lct_tags = LCT_MD_THREAD | LCT_DT_THREAD | LCT_MG_THREAD | LCT_LOCAL,
	.lct_init = dt_global_key_init,
	.lct_fini = dt_global_key_fini
};
EXPORT_SYMBOL(dt_key);

/* no lock is necessary to protect the list, because call-backs
 * are added during system startup. Please refer to "struct dt_device".
 */
void dt_txn_callback_add(struct dt_device *dev, struct dt_txn_callback *cb)
{
	list_add(&cb->dtc_linkage, &dev->dd_txn_callbacks);
}
EXPORT_SYMBOL(dt_txn_callback_add);

void dt_txn_callback_del(struct dt_device *dev, struct dt_txn_callback *cb)
{
	list_del_init(&cb->dtc_linkage);
}
EXPORT_SYMBOL(dt_txn_callback_del);

int dt_txn_hook_start(const struct lu_env *env,
		      struct dt_device *dev, struct thandle *th)
{
	int rc = 0;
	struct dt_txn_callback *cb;

	if (th->th_local)
		return 0;

	list_for_each_entry(cb, &dev->dd_txn_callbacks, dtc_linkage) {
		if (cb->dtc_txn_start == NULL ||
		    !(cb->dtc_tag & env->le_ctx.lc_tags))
			continue;
		rc = cb->dtc_txn_start(env, th, cb->dtc_cookie);
		if (rc < 0)
			break;
	}
	return rc;
}
EXPORT_SYMBOL(dt_txn_hook_start);

int dt_txn_hook_stop(const struct lu_env *env, struct thandle *txn)
{
	struct dt_device       *dev = txn->th_dev;
	struct dt_txn_callback *cb;
	int		     rc = 0;

	if (txn->th_local)
		return 0;

	list_for_each_entry(cb, &dev->dd_txn_callbacks, dtc_linkage) {
		if (cb->dtc_txn_stop == NULL ||
		    !(cb->dtc_tag & env->le_ctx.lc_tags))
			continue;
		rc = cb->dtc_txn_stop(env, txn, cb->dtc_cookie);
		if (rc < 0)
			break;
	}
	return rc;
}
EXPORT_SYMBOL(dt_txn_hook_stop);

void dt_txn_hook_commit(struct thandle *txn)
{
	struct dt_txn_callback *cb;

	if (txn->th_local)
		return;

	list_for_each_entry(cb, &txn->th_dev->dd_txn_callbacks,
				dtc_linkage) {
		if (cb->dtc_txn_commit)
			cb->dtc_txn_commit(txn, cb->dtc_cookie);
	}
}
EXPORT_SYMBOL(dt_txn_hook_commit);

int dt_device_init(struct dt_device *dev, struct lu_device_type *t)
{

	INIT_LIST_HEAD(&dev->dd_txn_callbacks);
	return lu_device_init(&dev->dd_lu_dev, t);
}
EXPORT_SYMBOL(dt_device_init);

void dt_device_fini(struct dt_device *dev)
{
	lu_device_fini(&dev->dd_lu_dev);
}
EXPORT_SYMBOL(dt_device_fini);

int dt_object_init(struct dt_object *obj,
		   struct lu_object_header *h, struct lu_device *d)

{
	return lu_object_init(&obj->do_lu, h, d);
}
EXPORT_SYMBOL(dt_object_init);

void dt_object_fini(struct dt_object *obj)
{
	lu_object_fini(&obj->do_lu);
}
EXPORT_SYMBOL(dt_object_fini);

int dt_try_as_dir(const struct lu_env *env, struct dt_object *obj)
{
	if (obj->do_index_ops == NULL)
		obj->do_ops->do_index_try(env, obj, &dt_directory_features);
	return obj->do_index_ops != NULL;
}
EXPORT_SYMBOL(dt_try_as_dir);

enum dt_format_type dt_mode_to_dft(__u32 mode)
{
	enum dt_format_type result;

	switch (mode & S_IFMT) {
	case S_IFDIR:
		result = DFT_DIR;
		break;
	case S_IFREG:
		result = DFT_REGULAR;
		break;
	case S_IFLNK:
		result = DFT_SYM;
		break;
	case S_IFCHR:
	case S_IFBLK:
	case S_IFIFO:
	case S_IFSOCK:
		result = DFT_NODE;
		break;
	default:
		LBUG();
		break;
	}
	return result;
}
EXPORT_SYMBOL(dt_mode_to_dft);

/**
 * lookup fid for object named \a name in directory \a dir.
 */

int dt_lookup_dir(const struct lu_env *env, struct dt_object *dir,
		  const char *name, struct lu_fid *fid)
{
	if (dt_try_as_dir(env, dir))
		return dt_lookup(env, dir, (struct dt_rec *)fid,
				 (const struct dt_key *)name, BYPASS_CAPA);
	return -ENOTDIR;
}
EXPORT_SYMBOL(dt_lookup_dir);

/* this differs from dt_locate by top_dev as parameter
 * but not one from lu_site */
struct dt_object *dt_locate_at(const struct lu_env *env,
			       struct dt_device *dev, const struct lu_fid *fid,
			       struct lu_device *top_dev)
{
	struct lu_object *lo, *n;

	lo = lu_object_find_at(env, top_dev, fid, NULL);
	if (IS_ERR(lo))
		return (void *)lo;

	LASSERT(lo != NULL);

	list_for_each_entry(n, &lo->lo_header->loh_layers, lo_linkage) {
		if (n->lo_dev == &dev->dd_lu_dev)
			return container_of0(n, struct dt_object, do_lu);
	}
	return ERR_PTR(-ENOENT);
}
EXPORT_SYMBOL(dt_locate_at);

/**
 * find a object named \a entry in given \a dfh->dfh_o directory.
 */
static int dt_find_entry(const struct lu_env *env, const char *entry, void *data)
{
	struct dt_find_hint  *dfh = data;
	struct dt_device     *dt = dfh->dfh_dt;
	struct lu_fid	*fid = dfh->dfh_fid;
	struct dt_object     *obj = dfh->dfh_o;
	int		   result;

	result = dt_lookup_dir(env, obj, entry, fid);
	lu_object_put(env, &obj->do_lu);
	if (result == 0) {
		obj = dt_locate(env, dt, fid);
		if (IS_ERR(obj))
			result = PTR_ERR(obj);
	}
	dfh->dfh_o = obj;
	return result;
}

/**
 * Abstract function which parses path name. This function feeds
 * path component to \a entry_func.
 */
int dt_path_parser(const struct lu_env *env,
		   char *path, dt_entry_func_t entry_func,
		   void *data)
{
	char *e;
	int rc = 0;

	while (1) {
		e = strsep(&path, "/");
		if (e == NULL)
			break;

		if (e[0] == 0) {
			if (!path || path[0] == '\0')
				break;
			continue;
		}
		rc = entry_func(env, e, data);
		if (rc)
			break;
	}

	return rc;
}

struct dt_object *
dt_store_resolve(const struct lu_env *env, struct dt_device *dt,
		 const char *path, struct lu_fid *fid)
{
	struct dt_thread_info *info = dt_info(env);
	struct dt_find_hint   *dfh = &info->dti_dfh;
	struct dt_object      *obj;
	char		      *local = info->dti_buf;
	int		       result;


	dfh->dfh_dt = dt;
	dfh->dfh_fid = fid;

	strncpy(local, path, DT_MAX_PATH);
	local[DT_MAX_PATH - 1] = '\0';

	result = dt->dd_ops->dt_root_get(env, dt, fid);
	if (result == 0) {
		obj = dt_locate(env, dt, fid);
		if (!IS_ERR(obj)) {
			dfh->dfh_o = obj;
			result = dt_path_parser(env, local, dt_find_entry, dfh);
			if (result != 0)
				obj = ERR_PTR(result);
			else
				obj = dfh->dfh_o;
		}
	} else {
		obj = ERR_PTR(result);
	}
	return obj;
}
EXPORT_SYMBOL(dt_store_resolve);

static struct dt_object *dt_reg_open(const struct lu_env *env,
				     struct dt_device *dt,
				     struct dt_object *p,
				     const char *name,
				     struct lu_fid *fid)
{
	struct dt_object *o;
	int result;

	result = dt_lookup_dir(env, p, name, fid);
	if (result == 0){
		o = dt_locate(env, dt, fid);
	}
	else
		o = ERR_PTR(result);

	return o;
}

/**
 * Open dt object named \a filename from \a dirname directory.
 *      \param  dt      dt device
 *      \param  fid     on success, object fid is stored in *fid
 */
struct dt_object *dt_store_open(const struct lu_env *env,
				struct dt_device *dt,
				const char *dirname,
				const char *filename,
				struct lu_fid *fid)
{
	struct dt_object *file;
	struct dt_object *dir;

	dir = dt_store_resolve(env, dt, dirname, fid);
	if (!IS_ERR(dir)) {
		file = dt_reg_open(env, dt, dir,
				   filename, fid);
		lu_object_put(env, &dir->do_lu);
	} else {
		file = dir;
	}
	return file;
}
EXPORT_SYMBOL(dt_store_open);

struct dt_object *dt_find_or_create(const struct lu_env *env,
				    struct dt_device *dt,
				    const struct lu_fid *fid,
				    struct dt_object_format *dof,
				    struct lu_attr *at)
{
	struct dt_object *dto;
	struct thandle *th;
	int rc;

	dto = dt_locate(env, dt, fid);
	if (IS_ERR(dto))
		return dto;

	LASSERT(dto != NULL);
	if (dt_object_exists(dto))
		return dto;

	th = dt_trans_create(env, dt);
	if (IS_ERR(th))
		GOTO(out, rc = PTR_ERR(th));

	rc = dt_declare_create(env, dto, at, NULL, dof, th);
	if (rc)
		GOTO(trans_stop, rc);

	rc = dt_trans_start_local(env, dt, th);
	if (rc)
		GOTO(trans_stop, rc);

	dt_write_lock(env, dto, 0);
	if (dt_object_exists(dto))
		GOTO(unlock, rc = 0);

	CDEBUG(D_OTHER, "create new object "DFID"\n", PFID(fid));

	rc = dt_create(env, dto, at, NULL, dof, th);
	if (rc)
		GOTO(unlock, rc);
	LASSERT(dt_object_exists(dto));
unlock:
	dt_write_unlock(env, dto);
trans_stop:
	dt_trans_stop(env, dt, th);
out:
	if (rc) {
		lu_object_put(env, &dto->do_lu);
		return ERR_PTR(rc);
	}
	return dto;
}
EXPORT_SYMBOL(dt_find_or_create);

/* dt class init function. */
int dt_global_init(void)
{
	int result;

	LU_CONTEXT_KEY_INIT(&dt_key);
	result = lu_context_key_register(&dt_key);
	return result;
}

void dt_global_fini(void)
{
	lu_context_key_degister(&dt_key);
}

/**
 * Generic read helper. May return an error for partial reads.
 *
 * \param env  lustre environment
 * \param dt   object to be read
 * \param buf  lu_buf to be filled, with buffer pointer and length
 * \param pos position to start reading, updated as data is read
 *
 * \retval real size of data read
 * \retval -ve errno on failure
 */
int dt_read(const struct lu_env *env, struct dt_object *dt,
	    struct lu_buf *buf, loff_t *pos)
{
	LASSERTF(dt != NULL, "dt is NULL when we want to read record\n");
	return dt->do_body_ops->dbo_read(env, dt, buf, pos, BYPASS_CAPA);
}
EXPORT_SYMBOL(dt_read);

/**
 * Read structures of fixed size from storage.  Unlike dt_read(), using
 * dt_record_read() will return an error for partial reads.
 *
 * \param env  lustre environment
 * \param dt   object to be read
 * \param buf  lu_buf to be filled, with buffer pointer and length
 * \param pos position to start reading, updated as data is read
 *
 * \retval 0 on successfully reading full buffer
 * \retval -EFAULT on short read
 * \retval -ve errno on failure
 */
int dt_record_read(const struct lu_env *env, struct dt_object *dt,
		   struct lu_buf *buf, loff_t *pos)
{
	int rc;

	LASSERTF(dt != NULL, "dt is NULL when we want to read record\n");

	rc = dt->do_body_ops->dbo_read(env, dt, buf, pos, BYPASS_CAPA);

	if (rc == buf->lb_len)
		rc = 0;
	else if (rc >= 0)
		rc = -EFAULT;
	return rc;
}
EXPORT_SYMBOL(dt_record_read);

int dt_record_write(const struct lu_env *env, struct dt_object *dt,
		    const struct lu_buf *buf, loff_t *pos, struct thandle *th)
{
	int rc;

	LASSERTF(dt != NULL, "dt is NULL when we want to write record\n");
	LASSERT(th != NULL);
	LASSERT(dt->do_body_ops);
	LASSERT(dt->do_body_ops->dbo_write);
	rc = dt->do_body_ops->dbo_write(env, dt, buf, pos, th, BYPASS_CAPA, 1);
	if (rc == buf->lb_len)
		rc = 0;
	else if (rc >= 0)
		rc = -EFAULT;
	return rc;
}
EXPORT_SYMBOL(dt_record_write);

int dt_declare_version_set(const struct lu_env *env, struct dt_object *o,
			   struct thandle *th)
{
	struct lu_buf vbuf;
	char *xname = XATTR_NAME_VERSION;

	LASSERT(o);
	vbuf.lb_buf = NULL;
	vbuf.lb_len = sizeof(dt_obj_version_t);
	return dt_declare_xattr_set(env, o, &vbuf, xname, 0, th);

}
EXPORT_SYMBOL(dt_declare_version_set);

void dt_version_set(const struct lu_env *env, struct dt_object *o,
		    dt_obj_version_t version, struct thandle *th)
{
	struct lu_buf vbuf;
	char *xname = XATTR_NAME_VERSION;
	int rc;

	LASSERT(o);
	vbuf.lb_buf = &version;
	vbuf.lb_len = sizeof(version);

	rc = dt_xattr_set(env, o, &vbuf, xname, 0, th, BYPASS_CAPA);
	if (rc < 0)
		CDEBUG(D_INODE, "Can't set version, rc %d\n", rc);
	return;
}
EXPORT_SYMBOL(dt_version_set);

dt_obj_version_t dt_version_get(const struct lu_env *env, struct dt_object *o)
{
	struct lu_buf vbuf;
	char *xname = XATTR_NAME_VERSION;
	dt_obj_version_t version;
	int rc;

	LASSERT(o);
	vbuf.lb_buf = &version;
	vbuf.lb_len = sizeof(version);
	rc = dt_xattr_get(env, o, &vbuf, xname, BYPASS_CAPA);
	if (rc != sizeof(version)) {
		CDEBUG(D_INODE, "Can't get version, rc %d\n", rc);
		version = 0;
	}
	return version;
}
EXPORT_SYMBOL(dt_version_get);

/* list of all supported index types */

/* directories */
const struct dt_index_features dt_directory_features;
EXPORT_SYMBOL(dt_directory_features);

/* scrub iterator */
const struct dt_index_features dt_otable_features;
EXPORT_SYMBOL(dt_otable_features);

/* lfsck */
const struct dt_index_features dt_lfsck_features = {
	.dif_flags		= DT_IND_UPDATE,
	.dif_keysize_min	= sizeof(struct lu_fid),
	.dif_keysize_max	= sizeof(struct lu_fid),
	.dif_recsize_min	= sizeof(__u8),
	.dif_recsize_max	= sizeof(__u8),
	.dif_ptrsize		= 4
};
EXPORT_SYMBOL(dt_lfsck_features);

/* accounting indexes */
const struct dt_index_features dt_acct_features = {
	.dif_flags		= DT_IND_UPDATE,
	.dif_keysize_min	= sizeof(__u64), /* 64-bit uid/gid */
	.dif_keysize_max	= sizeof(__u64), /* 64-bit uid/gid */
	.dif_recsize_min	= sizeof(struct lquota_acct_rec), /* 16 bytes */
	.dif_recsize_max	= sizeof(struct lquota_acct_rec), /* 16 bytes */
	.dif_ptrsize		= 4
};
EXPORT_SYMBOL(dt_acct_features);

/* global quota files */
const struct dt_index_features dt_quota_glb_features = {
	.dif_flags		= DT_IND_UPDATE,
	/* a different key would have to be used for per-directory quota */
	.dif_keysize_min	= sizeof(__u64), /* 64-bit uid/gid */
	.dif_keysize_max	= sizeof(__u64), /* 64-bit uid/gid */
	.dif_recsize_min	= sizeof(struct lquota_glb_rec), /* 32 bytes */
	.dif_recsize_max	= sizeof(struct lquota_glb_rec), /* 32 bytes */
	.dif_ptrsize		= 4
};
EXPORT_SYMBOL(dt_quota_glb_features);

/* slave quota files */
const struct dt_index_features dt_quota_slv_features = {
	.dif_flags		= DT_IND_UPDATE,
	/* a different key would have to be used for per-directory quota */
	.dif_keysize_min	= sizeof(__u64), /* 64-bit uid/gid */
	.dif_keysize_max	= sizeof(__u64), /* 64-bit uid/gid */
	.dif_recsize_min	= sizeof(struct lquota_slv_rec), /* 8 bytes */
	.dif_recsize_max	= sizeof(struct lquota_slv_rec), /* 8 bytes */
	.dif_ptrsize		= 4
};
EXPORT_SYMBOL(dt_quota_slv_features);

/* helper function returning what dt_index_features structure should be used
 * based on the FID sequence. This is used by OBD_IDX_READ RPC */
static inline const struct dt_index_features *dt_index_feat_select(__u64 seq,
								   __u32 mode)
{
	if (seq == FID_SEQ_QUOTA_GLB) {
		/* global quota index */
		if (!S_ISREG(mode))
			/* global quota index should be a regular file */
			return ERR_PTR(-ENOENT);
		return &dt_quota_glb_features;
	} else if (seq == FID_SEQ_QUOTA) {
		/* quota slave index */
		if (!S_ISREG(mode))
			/* slave index should be a regular file */
			return ERR_PTR(-ENOENT);
		return &dt_quota_slv_features;
	} else if (seq >= FID_SEQ_NORMAL) {
		/* object is part of the namespace, verify that it is a
		 * directory */
		if (!S_ISDIR(mode))
			/* sorry, we can only deal with directory */
			return ERR_PTR(-ENOTDIR);
		return &dt_directory_features;
	}

	return ERR_PTR(-EOPNOTSUPP);
}

/*
 * Fill a lu_idxpage with key/record pairs read for transfer via OBD_IDX_READ
 * RPC
 *
 * \param env - is the environment passed by the caller
 * \param lp  - is a pointer to the lu_page to fill
 * \param nob - is the maximum number of bytes that should be copied
 * \param iops - is the index operation vector associated with the index object
 * \param it   - is a pointer to the current iterator
 * \param attr - is the index attribute to pass to iops->rec()
 * \param arg  - is a pointer to the idx_info structure
 */
static int dt_index_page_build(const struct lu_env *env, union lu_page *lp,
			       int nob, const struct dt_it_ops *iops,
			       struct dt_it *it, __u32 attr, void *arg)
{
	struct idx_info		*ii = (struct idx_info *)arg;
	struct lu_idxpage	*lip = &lp->lp_idx;
	char			*entry;
	int			 rc, size;

	/* no support for variable key & record size for now */
	LASSERT((ii->ii_flags & II_FL_VARKEY) == 0);
	LASSERT((ii->ii_flags & II_FL_VARREC) == 0);

	/* initialize the header of the new container */
	memset(lip, 0, LIP_HDR_SIZE);
	lip->lip_magic = LIP_MAGIC;
	nob	   -= LIP_HDR_SIZE;

	/* compute size needed to store a key/record pair */
	size = ii->ii_recsize + ii->ii_keysize;
	if ((ii->ii_flags & II_FL_NOHASH) == 0)
		/* add hash if the client wants it */
		size += sizeof(__u64);

	entry = lip->lip_entries;
	do {
		char		*tmp_entry = entry;
		struct dt_key	*key;
		__u64		 hash;

		/* fetch 64-bit hash value */
		hash = iops->store(env, it);
		ii->ii_hash_end = hash;

		if (OBD_FAIL_CHECK(OBD_FAIL_OBD_IDX_READ_BREAK)) {
			if (lip->lip_nr != 0)
				GOTO(out, rc = 0);
		}

		if (nob < size) {
			if (lip->lip_nr == 0)
				GOTO(out, rc = -EINVAL);
			GOTO(out, rc = 0);
		}

		if ((ii->ii_flags & II_FL_NOHASH) == 0) {
			/* client wants to the 64-bit hash value associated with
			 * each record */
			memcpy(tmp_entry, &hash, sizeof(hash));
			tmp_entry += sizeof(hash);
		}

		/* then the key value */
		LASSERT(iops->key_size(env, it) == ii->ii_keysize);
		key = iops->key(env, it);
		memcpy(tmp_entry, key, ii->ii_keysize);
		tmp_entry += ii->ii_keysize;

		/* and finally the record */
		rc = iops->rec(env, it, (struct dt_rec *)tmp_entry, attr);
		if (rc != -ESTALE) {
			if (rc != 0)
				GOTO(out, rc);

			/* hash/key/record successfully copied! */
			lip->lip_nr++;
			if (unlikely(lip->lip_nr == 1 && ii->ii_count == 0))
				ii->ii_hash_start = hash;
			entry = tmp_entry + ii->ii_recsize;
			nob -= size;
		}

		/* move on to the next record */
		do {
			rc = iops->next(env, it);
		} while (rc == -ESTALE);

	} while (rc == 0);

	GOTO(out, rc);
out:
	if (rc >= 0 && lip->lip_nr > 0)
		/* one more container */
		ii->ii_count++;
	if (rc > 0)
		/* no more entries */
		ii->ii_hash_end = II_END_OFF;
	return rc;
}

/*
 * Walk index and fill lu_page containers with key/record pairs
 *
 * \param env - is the environment passed by the caller
 * \param obj - is the index object to parse
 * \param rdpg - is the lu_rdpg descriptor associated with the transfer
 * \param filler - is the callback function responsible for filling a lu_page
 *		 with key/record pairs in the format wanted by the caller
 * \param arg    - is an opaq argument passed to the filler function
 *
 * \retval sum (in bytes) of all filled lu_pages
 * \retval -ve errno on failure
 */
int dt_index_walk(const struct lu_env *env, struct dt_object *obj,
		  const struct lu_rdpg *rdpg, dt_index_page_build_t filler,
		  void *arg)
{
	struct dt_it		*it;
	const struct dt_it_ops	*iops;
	unsigned int		 pageidx, nob, nlupgs = 0;
	int			 rc;

	LASSERT(rdpg->rp_pages != NULL);
	LASSERT(obj->do_index_ops != NULL);

	nob = rdpg->rp_count;
	if (nob <= 0)
		return -EFAULT;

	/* Iterate through index and fill containers from @rdpg */
	iops = &obj->do_index_ops->dio_it;
	LASSERT(iops != NULL);
	it = iops->init(env, obj, rdpg->rp_attrs, BYPASS_CAPA);
	if (IS_ERR(it))
		return PTR_ERR(it);

	rc = iops->load(env, it, rdpg->rp_hash);
	if (rc == 0) {
		/*
		 * Iterator didn't find record with exactly the key requested.
		 *
		 * It is currently either
		 *
		 *     - positioned above record with key less than
		 *     requested---skip it.
		 *     - or not positioned at all (is in IAM_IT_SKEWED
		 *     state)---position it on the next item.
		 */
		rc = iops->next(env, it);
	} else if (rc > 0) {
		rc = 0;
	}

	/* Fill containers one after the other. There might be multiple
	 * containers per physical page.
	 *
	 * At this point and across for-loop:
	 *  rc == 0 -> ok, proceed.
	 *  rc >  0 -> end of index.
	 *  rc <  0 -> error. */
	for (pageidx = 0; rc == 0 && nob > 0; pageidx++) {
		union lu_page	*lp;
		int		 i;

		LASSERT(pageidx < rdpg->rp_npages);
		lp = kmap(rdpg->rp_pages[pageidx]);

		/* fill lu pages */
		for (i = 0; i < LU_PAGE_COUNT; i++, lp++, nob -= LU_PAGE_SIZE) {
			rc = filler(env, lp, min_t(int, nob, LU_PAGE_SIZE),
				    iops, it, rdpg->rp_attrs, arg);
			if (rc < 0)
				break;
			/* one more lu_page */
			nlupgs++;
			if (rc > 0)
				/* end of index */
				break;
		}
		kunmap(rdpg->rp_pages[i]);
	}

	iops->put(env, it);
	iops->fini(env, it);

	if (rc >= 0)
		rc = min_t(unsigned int, nlupgs * LU_PAGE_SIZE, rdpg->rp_count);

	return rc;
}
EXPORT_SYMBOL(dt_index_walk);

/**
 * Walk key/record pairs of an index and copy them into 4KB containers to be
 * transferred over the network. This is the common handler for OBD_IDX_READ
 * RPC processing.
 *
 * \param env - is the environment passed by the caller
 * \param dev - is the dt_device storing the index
 * \param ii  - is the idx_info structure packed by the client in the
 *	      OBD_IDX_READ request
 * \param rdpg - is the lu_rdpg descriptor
 *
 * \retval on success, return sum (in bytes) of all filled containers
 * \retval appropriate error otherwise.
 */
int dt_index_read(const struct lu_env *env, struct dt_device *dev,
		  struct idx_info *ii, const struct lu_rdpg *rdpg)
{
	const struct dt_index_features	*feat;
	struct dt_object		*obj;
	int				 rc;

	/* rp_count shouldn't be null and should be a multiple of the container
	 * size */
	if (rdpg->rp_count <= 0 && (rdpg->rp_count & (LU_PAGE_SIZE - 1)) != 0)
		return -EFAULT;

	if (fid_seq(&ii->ii_fid) >= FID_SEQ_NORMAL)
		/* we don't support directory transfer via OBD_IDX_READ for the
		 * time being */
		return -EOPNOTSUPP;

	if (!fid_is_quota(&ii->ii_fid))
		/* block access to all local files except quota files */
		return -EPERM;

	/* lookup index object subject to the transfer */
	obj = dt_locate(env, dev, &ii->ii_fid);
	if (IS_ERR(obj))
		return PTR_ERR(obj);
	if (dt_object_exists(obj) == 0)
		GOTO(out, rc = -ENOENT);

	/* fetch index features associated with index object */
	feat = dt_index_feat_select(fid_seq(&ii->ii_fid),
				    lu_object_attr(&obj->do_lu));
	if (IS_ERR(feat))
		GOTO(out, rc = PTR_ERR(feat));

	/* load index feature if not done already */
	if (obj->do_index_ops == NULL) {
		rc = obj->do_ops->do_index_try(env, obj, feat);
		if (rc)
			GOTO(out, rc);
	}

	/* fill ii_flags with supported index features */
	ii->ii_flags &= II_FL_NOHASH;

	ii->ii_keysize = feat->dif_keysize_max;
	if ((feat->dif_flags & DT_IND_VARKEY) != 0) {
		/* key size is variable */
		ii->ii_flags |= II_FL_VARKEY;
		/* we don't support variable key size for the time being */
		GOTO(out, rc = -EOPNOTSUPP);
	}

	ii->ii_recsize = feat->dif_recsize_max;
	if ((feat->dif_flags & DT_IND_VARREC) != 0) {
		/* record size is variable */
		ii->ii_flags |= II_FL_VARREC;
		/* we don't support variable record size for the time being */
		GOTO(out, rc = -EOPNOTSUPP);
	}

	if ((feat->dif_flags & DT_IND_NONUNQ) != 0)
		/* key isn't necessarily unique */
		ii->ii_flags |= II_FL_NONUNQ;

	dt_read_lock(env, obj, 0);
	/* fetch object version before walking the index */
	ii->ii_version = dt_version_get(env, obj);

	/* walk the index and fill lu_idxpages with key/record pairs */
	rc = dt_index_walk(env, obj, rdpg, dt_index_page_build ,ii);
	dt_read_unlock(env, obj);

	if (rc == 0) {
		/* index is empty */
		LASSERT(ii->ii_count == 0);
		ii->ii_hash_end = II_END_OFF;
	}

	GOTO(out, rc);
out:
	lu_object_put(env, &obj->do_lu);
	return rc;
}
EXPORT_SYMBOL(dt_index_read);

#ifdef LPROCFS

int lprocfs_dt_rd_blksize(char *page, char **start, off_t off,
			  int count, int *eof, void *data)
{
	struct dt_device *dt = data;
	struct obd_statfs osfs;

	int rc = dt_statfs(NULL, dt, &osfs);
	if (rc == 0) {
		*eof = 1;
		rc = snprintf(page, count, "%u\n",
				(unsigned) osfs.os_bsize);
	}

	return rc;
}
EXPORT_SYMBOL(lprocfs_dt_rd_blksize);

int lprocfs_dt_rd_kbytestotal(char *page, char **start, off_t off,
			      int count, int *eof, void *data)
{
	struct dt_device *dt = data;
	struct obd_statfs osfs;

	int rc = dt_statfs(NULL, dt, &osfs);
	if (rc == 0) {
		__u32 blk_size = osfs.os_bsize >> 10;
		__u64 result = osfs.os_blocks;

		while (blk_size >>= 1)
			result <<= 1;

		*eof = 1;
		rc = snprintf(page, count, LPU64"\n", result);
	}

	return rc;
}
EXPORT_SYMBOL(lprocfs_dt_rd_kbytestotal);

int lprocfs_dt_rd_kbytesfree(char *page, char **start, off_t off,
			     int count, int *eof, void *data)
{
	struct dt_device *dt = data;
	struct obd_statfs osfs;

	int rc = dt_statfs(NULL, dt, &osfs);
	if (rc == 0) {
		__u32 blk_size = osfs.os_bsize >> 10;
		__u64 result = osfs.os_bfree;

		while (blk_size >>= 1)
			result <<= 1;

		*eof = 1;
		rc = snprintf(page, count, LPU64"\n", result);
	}

	return rc;
}
EXPORT_SYMBOL(lprocfs_dt_rd_kbytesfree);

int lprocfs_dt_rd_kbytesavail(char *page, char **start, off_t off,
			      int count, int *eof, void *data)
{
	struct dt_device *dt = data;
	struct obd_statfs osfs;

	int rc = dt_statfs(NULL, dt, &osfs);
	if (rc == 0) {
		__u32 blk_size = osfs.os_bsize >> 10;
		__u64 result = osfs.os_bavail;

		while (blk_size >>= 1)
			result <<= 1;

		*eof = 1;
		rc = snprintf(page, count, LPU64"\n", result);
	}

	return rc;
}
EXPORT_SYMBOL(lprocfs_dt_rd_kbytesavail);

int lprocfs_dt_rd_filestotal(char *page, char **start, off_t off,
			     int count, int *eof, void *data)
{
	struct dt_device *dt = data;
	struct obd_statfs osfs;

	int rc = dt_statfs(NULL, dt, &osfs);
	if (rc == 0) {
		*eof = 1;
		rc = snprintf(page, count, LPU64"\n", osfs.os_files);
	}

	return rc;
}
EXPORT_SYMBOL(lprocfs_dt_rd_filestotal);

int lprocfs_dt_rd_filesfree(char *page, char **start, off_t off,
			    int count, int *eof, void *data)
{
	struct dt_device *dt = data;
	struct obd_statfs osfs;

	int rc = dt_statfs(NULL, dt, &osfs);
	if (rc == 0) {
		*eof = 1;
		rc = snprintf(page, count, LPU64"\n", osfs.os_ffree);
	}

	return rc;
}
EXPORT_SYMBOL(lprocfs_dt_rd_filesfree);

#endif /* LPROCFS */