/*
 * 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) 2009, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2012, 2017, Intel Corporation.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 *
 * lustre/osd-zfs/osd_oi.c
 * OI functions to map fid to dnode
 *
 * Author: Alex Zhuravlev <bzzz@whamcloud.com>
 * Author: Mike Pershin <tappro@whamcloud.com>
 * Author: Di Wang <di.wang@intel.com>
 */

#define DEBUG_SUBSYSTEM S_OSD

#include <libcfs/libcfs.h>
#include <obd_support.h>
#include <lustre_net.h>
#include <obd.h>
#include <obd_class.h>
#include <lustre_disk.h>
#include <lustre_fid.h>

#include "osd_internal.h"

#include <sys/dnode.h>
#include <sys/dbuf.h>
#include <sys/spa.h>
#include <sys/stat.h>
#include <sys/zap.h>
#include <sys/spa_impl.h>
#include <sys/zfs_znode.h>
#include <sys/dmu_tx.h>
#include <sys/dmu_objset.h>
#include <sys/dsl_prop.h>
#include <sys/sa_impl.h>
#include <sys/txg.h>
#include <lustre_scrub.h>

#define OSD_OI_FID_NR         (1UL << 7)
unsigned int osd_oi_count = OSD_OI_FID_NR;


/*
 * zfs osd maintains names for known fids in the name hierarchy
 * so that one can mount filesystem with regular ZFS stack and
 * access files
 */
struct named_oid {
	unsigned long	 oid;
	char		*name;
};

static const struct named_oid oids[] = {
	{ .oid = LAST_RECV_OID,	       .name = LAST_RCVD },
	{ .oid = OFD_LAST_GROUP_OID,   .name = "LAST_GROUP" },
	{ .oid = LLOG_CATALOGS_OID,    .name = "CATALOGS" },
	{ .oid = MGS_CONFIGS_OID,      /*MOUNT_CONFIGS_DIR*/ },
	{ .oid = FID_SEQ_SRV_OID,      .name = "seq_srv" },
	{ .oid = FID_SEQ_CTL_OID,      .name = "seq_ctl" },
	{ .oid = FLD_INDEX_OID,	       .name = "fld" },
	{ .oid = MDD_LOV_OBJ_OID,      .name = LOV_OBJID },
	{ .oid = OFD_HEALTH_CHECK_OID, .name = HEALTH_CHECK },
	{ .oid = REPLY_DATA_OID,       .name = REPLY_DATA },
	{ .oid = MDD_LOV_OBJ_OSEQ,     .name = LOV_OBJSEQ },
	{ .oid = BATCHID_COMMITTED_OID, .name = "BATCHID" },
	{ .oid = 0 }
};

static inline bool fid_is_objseq(const struct lu_fid *fid)
{
	return fid->f_seq == FID_SEQ_LOCAL_FILE &&
		fid->f_oid == MDD_LOV_OBJ_OSEQ;
}

static inline bool fid_is_batchid(const struct lu_fid *fid)
{
	return fid->f_seq == FID_SEQ_LOCAL_FILE &&
		fid->f_oid == BATCHID_COMMITTED_OID;
}

static char *oid2name(const unsigned long oid)
{
	int i = 0;

	while (oids[i].oid) {
		if (oids[i].oid == oid)
			return oids[i].name;
		i++;
	}
	return NULL;
}

/**
 * Lookup an existing OI by the given name.
 */
static int
osd_oi_lookup(const struct lu_env *env, struct osd_device *o,
	      uint64_t parent, const char *name, struct osd_oi *oi)
{
	struct zpl_direntry	*zde = &osd_oti_get(env)->oti_zde.lzd_reg;
	int			 rc;

	rc = -zap_lookup(o->od_os, parent, name, 8, 1, (void *)zde);
	if (rc)
		return rc;

	rc = strlcpy(oi->oi_name, name, sizeof(oi->oi_name));
	if (rc >= sizeof(oi->oi_name))
		return -E2BIG;

	oi->oi_zapid = zde->zde_dnode;

	return 0;
}

static int osd_obj_create(const struct lu_env *env, struct osd_device *o,
			  uint64_t parent, const char *name, uint64_t *child,
			  const struct lu_fid *fid, bool isdir)
{
	struct osd_thread_info *info = osd_oti_get(env);
	struct zpl_direntry *zde = &info->oti_zde.lzd_reg;
	struct lustre_mdt_attrs *lma = &info->oti_mdt_attrs;
	struct lu_attr *la = &info->oti_la;
	sa_handle_t *sa_hdl = NULL;
	nvlist_t *nvbuf = NULL;
	dmu_tx_t *tx;
	uint64_t oid;
	__u32 compat = LMAC_NOT_IN_OI;
	int rc;
	ENTRY;

	if (o->od_dt_dev.dd_rdonly)
		RETURN(-EROFS);

	memset(la, 0, sizeof(*la));
	la->la_valid = LA_MODE | LA_UID | LA_GID;
	la->la_mode = S_IRUGO | S_IWUSR | (isdir ? S_IXUGO | S_IFDIR : S_IFREG);

	if (fid) {
		rc = -nvlist_alloc(&nvbuf, NV_UNIQUE_NAME, KM_SLEEP);
		if (rc)
			RETURN(rc);

		if (o->od_is_ost)
			compat |= LMAC_FID_ON_OST;
		lustre_lma_init(lma, fid, compat, 0);
		lustre_lma_swab(lma);
		rc = -nvlist_add_byte_array(nvbuf, XATTR_NAME_LMA,
					    (uchar_t *)lma, sizeof(*lma));
		if (rc)
			GOTO(out, rc);
	}

	/* create fid-to-dnode index */
	tx = dmu_tx_create(o->od_os);
	if (!tx)
		GOTO(out, rc = -ENOMEM);

	dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, FALSE, NULL);
	dmu_tx_hold_bonus(tx, parent);
	dmu_tx_hold_zap(tx, parent, TRUE, name);
	dmu_tx_hold_sa_create(tx, ZFS_SA_BASE_ATTR_SIZE);
	rc = -dmu_tx_assign(tx, TXG_WAIT);
	if (rc) {
		dmu_tx_abort(tx);
		GOTO(out, rc);
	}

	if (isdir)
		oid = osd_zap_create_flags(o->od_os, 0, ZAP_FLAG_HASH64,
					   DMU_OT_DIRECTORY_CONTENTS,
					   14, DN_MAX_INDBLKSHIFT, 0, tx);
	else
		oid = osd_dmu_object_alloc(o->od_os, DMU_OTN_UINT8_METADATA,
					   0, 0, tx);
	rc = -sa_handle_get(o->od_os, oid, NULL, SA_HDL_PRIVATE, &sa_hdl);
	if (rc)
		GOTO(commit, rc);

	rc = __osd_attr_init(env, o, NULL, sa_hdl, tx, la, parent, nvbuf);
	sa_handle_destroy(sa_hdl);
	if (rc)
		GOTO(commit, rc);

	zde->zde_dnode = oid;
	zde->zde_pad = 0;
	zde->zde_type = IFTODT(isdir ? S_IFDIR : S_IFREG);
	rc = -zap_add(o->od_os, parent, name, 8, 1, (void *)zde, tx);

	GOTO(commit, rc);

commit:
	if (rc)
		dmu_object_free(o->od_os, oid, tx);
	else
		*child = oid;
	dmu_tx_commit(tx);
out:
	if (nvbuf)
		nvlist_free(nvbuf);
	return rc;
}

static int
osd_oi_find_or_create(const struct lu_env *env, struct osd_device *o,
		      uint64_t parent, const char *name, uint64_t *child)
{
	struct osd_oi	oi;
	int		rc;

	rc = osd_oi_lookup(env, o, parent, name, &oi);
	if (rc == 0)
		*child = oi.oi_zapid;
	else if (rc == -ENOENT)
		rc = osd_obj_create(env, o, parent, name, child, NULL, true);

	return rc;
}

int osd_obj_find_or_create(const struct lu_env *env, struct osd_device *o,
			   uint64_t parent, const char *name, uint64_t *child,
			   const struct lu_fid *fid, bool isdir)
{
	struct osd_oi oi;
	int rc;

	rc = osd_oi_lookup(env, o, parent, name, &oi);
	if (!rc)
		*child = oi.oi_zapid;
	else if (rc == -ENOENT)
		rc = osd_obj_create(env, o, parent, name, child, fid, isdir);

	return rc;
}

/**
 * Lookup the target index/flags of the fid, so it will know where
 * the object is located (tgt index) and it is MDT or OST object.
 */
int osd_fld_lookup(const struct lu_env *env, struct osd_device *osd,
		   u64 seq, struct lu_seq_range *range)
{
	struct seq_server_site	*ss = osd_seq_site(osd);

	if (fid_seq_is_idif(seq)) {
		fld_range_set_ost(range);
		range->lsr_index = idif_ost_idx(seq);
		return 0;
	}

	if (!fid_seq_in_fldb(seq)) {
		fld_range_set_mdt(range);
		if (ss != NULL)
			/* FIXME: If ss is NULL, it suppose not get lsr_index
			 * at all */
			range->lsr_index = ss->ss_node_id;
		return 0;
	}

	/* The seq_server_site may be NOT ready during initial OI scrub */
	if (unlikely(!ss || !ss->ss_server_fld ||
		     !ss->ss_server_fld->lsf_cache))
		return -ENOENT;

	fld_range_set_any(range);
	/* OSD will only do local fld lookup */
	return fld_local_lookup(env, ss->ss_server_fld, seq, range);
}

int fid_is_on_ost(const struct lu_env *env, struct osd_device *osd,
		  const struct lu_fid *fid)
{
	struct lu_seq_range	*range = &osd_oti_get(env)->oti_seq_range;
	int			rc;
	ENTRY;

	if (fid_is_idif(fid))
		RETURN(1);

	if (unlikely(fid_is_local_file(fid) || fid_is_llog(fid)) ||
		     fid_is_name_llog(fid) || fid_is_quota(fid) ||
		     fid_is_igif(fid))
		RETURN(0);

	rc = osd_fld_lookup(env, osd, fid_seq(fid), range);
	if (rc != 0) {
		/* During upgrade, OST FLDB might not be loaded because
		 * OST FLDB is not created until 2.6, so if some DNE
		 * filesystem upgrade from 2.5 to 2.7/2.8, they will
		 * not be able to find the sequence from local FLDB
		 * cache see fld_index_init(). */
		if (rc == -ENOENT && osd->od_is_ost)
			RETURN(1);

		if (rc != -ENOENT)
			CERROR("%s: "DFID" lookup failed: rc = %d\n",
			       osd_name(osd), PFID(fid), rc);
		RETURN(0);
	}

	if (fld_range_is_ost(range))
		RETURN(1);

	RETURN(0);
}

static struct osd_seq *osd_seq_find_locked(struct osd_seq_list *seq_list,
					   u64 seq)
{
	struct osd_seq *osd_seq;

	list_for_each_entry(osd_seq, &seq_list->osl_seq_list, os_seq_list) {
		if (osd_seq->os_seq == seq)
			return osd_seq;
	}
	return NULL;
}

static struct osd_seq *osd_seq_find(struct osd_seq_list *seq_list, u64 seq)
{
	struct osd_seq *osd_seq;

	read_lock(&seq_list->osl_seq_list_lock);
	osd_seq = osd_seq_find_locked(seq_list, seq);
	read_unlock(&seq_list->osl_seq_list_lock);

	return osd_seq;
}

static struct osd_seq *osd_find_or_add_seq(const struct lu_env *env,
					   struct osd_device *osd, u64 seq)
{
	struct osd_seq_list	*seq_list = &osd->od_seq_list;
	struct osd_seq		*osd_seq;
	char			*key = osd_oti_get(env)->oti_buf;
	char			*seq_name = osd_oti_get(env)->oti_str;
	struct osd_oi		oi;
	uint64_t		sdb, odb;
	int			i;
	int			rc = 0;
	ENTRY;

	osd_seq = osd_seq_find(seq_list, seq);
	if (osd_seq != NULL)
		RETURN(osd_seq);

	down(&seq_list->osl_seq_init_sem);
	/* Check again, in case some one else already add it
	 * to the list */
	osd_seq = osd_seq_find(seq_list, seq);
	if (osd_seq != NULL)
		GOTO(out, rc = 0);

	OBD_ALLOC_PTR(osd_seq);
	if (osd_seq == NULL)
		GOTO(out, rc = -ENOMEM);

	INIT_LIST_HEAD(&osd_seq->os_seq_list);
	osd_seq->os_seq = seq;

	/* Init subdir count to be 32, but each seq can have
	 * different subdir count */
	osd_seq->os_subdir_count = OSD_OST_MAP_SIZE;
	OBD_ALLOC(osd_seq->os_compat_dirs,
		  sizeof(uint64_t) * osd_seq->os_subdir_count);
	if (osd_seq->os_compat_dirs == NULL)
		GOTO(out, rc = -ENOMEM);

	oi.oi_zapid = osd->od_O_id;
	sprintf(seq_name, (fid_seq_is_rsvd(seq) ||
		fid_seq_is_mdt0(seq)) ?  "%llu" : "%llx",
		fid_seq_is_idif(seq) ? 0 : seq);

	rc = osd_oi_find_or_create(env, osd, oi.oi_zapid, seq_name, &odb);
	if (rc != 0) {
		CERROR("%s: Can not create %s : rc = %d\n",
		       osd_name(osd), seq_name, rc);
		GOTO(out, rc);
	}

	osd_seq->os_oid = odb;
	for (i = 0; i < OSD_OST_MAP_SIZE; i++) {
		sprintf(key, "d%d", i);
		rc = osd_oi_find_or_create(env, osd, odb, key, &sdb);
		if (rc)
			GOTO(out, rc);
		osd_seq->os_compat_dirs[i] = sdb;
	}

	write_lock(&seq_list->osl_seq_list_lock);
	list_add(&osd_seq->os_seq_list, &seq_list->osl_seq_list);
	write_unlock(&seq_list->osl_seq_list_lock);
out:
	up(&seq_list->osl_seq_init_sem);
	if (rc != 0) {
		if (osd_seq != NULL && osd_seq->os_compat_dirs != NULL)
			OBD_FREE(osd_seq->os_compat_dirs,
				 sizeof(uint64_t) * osd_seq->os_subdir_count);
		if (osd_seq != NULL)
			OBD_FREE_PTR(osd_seq);
		osd_seq = ERR_PTR(rc);
	}
	RETURN(osd_seq);
}

static uint64_t
osd_get_idx_for_ost_obj_compat(const struct lu_env *env, struct osd_device *osd,
			       const struct lu_fid *fid, char *buf, int bufsize)
{
	struct osd_seq	*osd_seq;
	unsigned long	b;
	u64		id;
	int		rc;

	osd_seq = osd_find_or_add_seq(env, osd, fid_seq(fid));
	if (IS_ERR(osd_seq)) {
		CERROR("%s: Can not find seq group "DFID"\n", osd_name(osd),
		       PFID(fid));
		return PTR_ERR(osd_seq);
	}

	if (fid_is_last_id(fid)) {
		id = 0;
	} else {
		rc = fid_to_ostid(fid, &osd_oti_get(env)->oti_ostid);
		LASSERT(rc == 0); /* we should not get here with IGIF */
		id = ostid_id(&osd_oti_get(env)->oti_ostid);
	}

	b = id % OSD_OST_MAP_SIZE;
	LASSERT(osd_seq->os_compat_dirs[b]);

	if (buf)
		snprintf(buf, bufsize, "%llu", id);

	return osd_seq->os_compat_dirs[b];
}

/*
 * objects w/o a natural reference (unlike a file on a MDS)
 * are put under a special hierarchy /O/<seq>/d0..dXX
 * this function returns a directory specific fid belongs to
 */
static uint64_t
osd_get_idx_for_ost_obj(const struct lu_env *env, struct osd_device *osd,
			const struct lu_fid *fid, char *buf, int bufsize)
{
	struct osd_seq	*osd_seq;
	unsigned long	b;
	u64		id;
	int		rc;

	osd_seq = osd_find_or_add_seq(env, osd, fid_seq(fid));
	if (IS_ERR(osd_seq)) {
		CERROR("%s: Can not find seq group "DFID"\n", osd_name(osd),
		       PFID(fid));
		return PTR_ERR(osd_seq);
	}

	if (fid_is_last_id(fid)) {
		if (buf)
			snprintf(buf, bufsize, "LAST_ID");

		return osd_seq->os_oid;
	}

	rc = fid_to_ostid(fid, &osd_oti_get(env)->oti_ostid);
	LASSERT(rc == 0); /* we should not get here with IGIF */

	id = ostid_id(&osd_oti_get(env)->oti_ostid);
	b = id % OSD_OST_MAP_SIZE;
	LASSERT(osd_seq->os_compat_dirs[b]);

	if (buf)
		snprintf(buf, bufsize, "%llu", id);

	return osd_seq->os_compat_dirs[b];
}

/*
 * Determine the zap object id which is being used as the OI for the
 * given fid.  The lowest N bits in the sequence ID are used as the
 * index key.  On failure 0 is returned which zfs treats internally
 * as an invalid object id.
 */
static uint64_t
osd_get_idx_for_fid(struct osd_device *osd, const struct lu_fid *fid,
		    char *buf, dnode_t **zdn, int bufsize)
{
	struct osd_oi *oi;

	oi = osd_fid2oi(osd, fid);
	if (buf)
		osd_fid2str(buf, fid, bufsize);
	if (zdn)
		*zdn = oi->oi_dn;

	return oi->oi_zapid;
}

uint64_t
osd_get_name_n_idx_compat(const struct lu_env *env, struct osd_device *osd,
			  const struct lu_fid *fid, char *buf, int bufsize,
			  dnode_t **zdn)
{
	uint64_t zapid;

	LASSERT(fid);
	LASSERT(!fid_is_acct(fid));

	if (zdn != NULL)
		*zdn = NULL;

	if (fid_is_echo(fid) || fid_is_on_ost(env, osd, fid)) {
		zapid = osd_get_idx_for_ost_obj_compat(env, osd, fid,
						       buf, bufsize);
	} else if (unlikely(fid_seq(fid) == FID_SEQ_LOCAL_FILE)) {
		/* special objects with fixed known fids get their name */
		char *name = oid2name(fid_oid(fid));

		if (name) {
			zapid = osd->od_root;
			if (buf)
				strncpy(buf, name, bufsize);
		} else {
			zapid = osd_get_idx_for_fid(osd, fid, buf, NULL,
						    bufsize);
		}
	} else {
		zapid = osd_get_idx_for_fid(osd, fid, buf, zdn, bufsize);
	}

	return zapid;
}

uint64_t osd_get_name_n_idx(const struct lu_env *env, struct osd_device *osd,
			    const struct lu_fid *fid, char *buf, int bufsize,
			    dnode_t **zdn)
{
	uint64_t zapid;

	LASSERT(fid);
	LASSERT(!fid_is_acct(fid));

	if (zdn != NULL)
		*zdn = NULL;

	if (fid_is_echo(fid) || fid_is_last_id(fid) ||
	    fid_is_on_ost(env, osd, fid)) {
		zapid = osd_get_idx_for_ost_obj(env, osd, fid, buf, bufsize);
	} else if (unlikely(fid_seq(fid) == FID_SEQ_LOCAL_FILE)) {
		/* special objects with fixed known fids get their name */
		char *name = oid2name(fid_oid(fid));

		if (name) {
			zapid = osd->od_root;
			if (buf)
				strncpy(buf, name, bufsize);
		} else {
			zapid = osd_get_idx_for_fid(osd, fid, buf, NULL,
						    bufsize);
		}
	} else {
		zapid = osd_get_idx_for_fid(osd, fid, buf, zdn, bufsize);
	}

	return zapid;
}

static inline int fid_is_fs_root(const struct lu_fid *fid)
{
	/* Map root inode to special local object FID */
	return fid_seq(fid) == FID_SEQ_LOCAL_FILE &&
		fid_oid(fid) == OSD_FS_ROOT_OID;
}

int osd_fid_lookup(const struct lu_env *env, struct osd_device *dev,
		   const struct lu_fid *fid, uint64_t *oid)
{
	struct osd_thread_info	*info = osd_oti_get(env);
	char			*buf = info->oti_buf;
	dnode_t *zdn;
	uint64_t zapid;
	int			rc = 0;
	ENTRY;

	if (OBD_FAIL_CHECK(OBD_FAIL_SRV_ENOENT))
		RETURN(-ENOENT);

	LASSERT(!fid_is_acct(fid));

	if (unlikely(fid_is_fs_root(fid))) {
		*oid = dev->od_root;
	} else {
		zapid = osd_get_name_n_idx(env, dev, fid, buf,
					   sizeof(info->oti_buf), &zdn);
		rc = osd_zap_lookup(dev, zapid, zdn, buf,
				    8, 1, &info->oti_zde);
		if (rc == -ENOENT) {
			if (unlikely(fid_is_last_id(fid))) {
				zapid = osd_get_name_n_idx_compat(env, dev, fid,
					buf, sizeof(info->oti_buf), &zdn);
				rc = osd_zap_lookup(dev, zapid, zdn, buf,
						    8, 1, &info->oti_zde);
			} else if (fid_is_objseq(fid) || fid_is_batchid(fid)) {
				zapid = osd_get_idx_for_fid(dev, fid,
					buf, NULL, sizeof(info->oti_buf));
				rc = osd_zap_lookup(dev, zapid, zdn, buf,
						    8, 1, &info->oti_zde);
			}
		}

		if (rc)
			RETURN(rc);
		*oid = info->oti_zde.lzd_reg.zde_dnode;
	}

	if (rc == 0)
		osd_dmu_prefetch(dev->od_os, *oid, 0, 0, 0,
				 ZIO_PRIORITY_ASYNC_READ);

	RETURN(rc);
}

/**
 * Close an entry in a specific slot.
 */
static void
osd_oi_remove_table(const struct lu_env *env, struct osd_device *o, int key)
{
	struct osd_oi *oi;

	LASSERT(key < o->od_oi_count);

	oi = o->od_oi_table[key];
	if (oi) {
		if (oi->oi_dn)
			osd_dnode_rele(oi->oi_dn);
		OBD_FREE_PTR(oi);
		o->od_oi_table[key] = NULL;
	}
}

/**
 * Allocate and open a new entry in the specified unused slot.
 */
static int
osd_oi_add_table(const struct lu_env *env, struct osd_device *o,
		 char *name, int key)
{
	struct osd_oi *oi;
	int rc;

	LASSERT(key < o->od_oi_count);
	LASSERT(o->od_oi_table[key] == NULL);

	OBD_ALLOC_PTR(oi);
	if (oi == NULL)
		return -ENOMEM;

	rc = osd_oi_lookup(env, o, o->od_root, name, oi);
	if (rc) {
		OBD_FREE_PTR(oi);
		return rc;
	}

	o->od_oi_table[key] = oi;
	__osd_obj2dnode(o->od_os, oi->oi_zapid, &oi->oi_dn);

	return 0;
}

/**
 * Depopulate the OI table.
 */
static void
osd_oi_close_table(const struct lu_env *env, struct osd_device *o)
{
	int i;

	for (i = 0; i < o->od_oi_count; i++)
		osd_oi_remove_table(env, o, i);
}

/**
 * Populate the OI table based.
 */
static int
osd_oi_open_table(const struct lu_env *env, struct osd_device *o, int count)
{
	char name[16];
	int  i, rc = 0;
	ENTRY;

	for (i = 0; i < count; i++) {
		sprintf(name, "%s.%d", DMU_OSD_OI_NAME_BASE, i);
		rc = osd_oi_add_table(env, o, name, i);
		if (rc) {
			osd_oi_close_table(env, o);
			break;
		}
	}

	RETURN(rc);
}

/**
 * Determine if the type and number of OIs used by this file system.
 */
static int osd_oi_probe(const struct lu_env *env, struct osd_device *o)
{
	struct lustre_scrub *scrub = &o->od_scrub;
	struct scrub_file *sf = &scrub->os_file;
	struct osd_oi oi;
	char name[16];
	int max = sf->sf_oi_count > 0 ? sf->sf_oi_count : OSD_OI_FID_NR_MAX;
	int count;
	int rc;
	ENTRY;

	/*
	 * Check for multiple OIs and determine the count.  There is no
	 * gap handling, if an OI is missing the wrong size can be returned.
	 * The only safeguard is that we know the number of OIs must be a
	 * power of two and this is checked for basic sanity.
	 */
	for (count = 0; count < max; count++) {
		snprintf(name, sizeof(name) - 1, "%s.%d",
			 DMU_OSD_OI_NAME_BASE, count);
		rc = osd_oi_lookup(env, o, o->od_root, name, &oi);
		if (!rc)
			continue;

		if (rc == -ENOENT) {
			if (sf->sf_oi_count == 0)
				RETURN(count);

			zfs_set_bit(count, sf->sf_oi_bitmap);
			continue;
		}

		if (rc)
			RETURN(rc);
	}

	RETURN(count);
}

static void osd_ost_seq_fini(const struct lu_env *env, struct osd_device *osd)
{
	struct osd_seq_list	*osl = &osd->od_seq_list;
	struct osd_seq		*osd_seq, *tmp;

	write_lock(&osl->osl_seq_list_lock);
	list_for_each_entry_safe(osd_seq, tmp, &osl->osl_seq_list,
				 os_seq_list) {
		list_del(&osd_seq->os_seq_list);
		OBD_FREE(osd_seq->os_compat_dirs,
			 sizeof(uint64_t) * osd_seq->os_subdir_count);
		OBD_FREE(osd_seq, sizeof(*osd_seq));
	}
	write_unlock(&osl->osl_seq_list_lock);

	return;
}

/**
 * Create /O subdirectory to map legacy OST objects for compatibility.
 */
static int
osd_oi_init_compat(const struct lu_env *env, struct osd_device *o)
{
	uint64_t sdb;
	int rc;
	ENTRY;

	rc = osd_oi_find_or_create(env, o, o->od_root, "O", &sdb);
	if (!rc)
		o->od_O_id = sdb;

	RETURN(rc);
}

static int
osd_oi_init_index_backup(const struct lu_env *env, struct osd_device *o)
{
	struct lu_fid *fid = &osd_oti_get(env)->oti_fid;
	int rc;
	ENTRY;

	lu_local_obj_fid(fid, INDEX_BACKUP_OID);
	rc = osd_obj_find_or_create(env, o, o->od_root, INDEX_BACKUP_DIR,
				    &o->od_index_backup_id, fid, true);

	RETURN(rc);
}

static void
osd_oi_init_remote_parent(const struct lu_env *env, struct osd_device *o)
{
	uint64_t sdb;
	int rc;
	ENTRY;

	if (o->od_is_ost) {
		o->od_remote_parent_dir = ZFS_NO_OBJECT;
	} else {
		/* Remote parent only used for cross-MDT objects,
		 * it is usless for single MDT case or under read
		 * only mode. So ignore the failure. */
		rc = osd_oi_find_or_create(env, o, o->od_root,
					   REMOTE_PARENT_DIR, &sdb);
		if (!rc)
			o->od_remote_parent_dir = sdb;
		else
			o->od_remote_parent_dir = ZFS_NO_OBJECT;
	}
}

/**
 * Initialize the OIs by either opening or creating them as needed.
 */
int osd_oi_init(const struct lu_env *env, struct osd_device *o)
{
	struct lustre_scrub *scrub = &o->od_scrub;
	struct scrub_file *sf = &scrub->os_file;
	char *key = osd_oti_get(env)->oti_buf;
	uint64_t sdb;
	int i, rc, count;
	ENTRY;

	LASSERTF((sf->sf_oi_count & (sf->sf_oi_count - 1)) == 0,
		 "Invalid OI count in scrub file %d\n", sf->sf_oi_count);

	rc = osd_oi_init_index_backup(env, o);
	if (rc)
		RETURN(rc);

	osd_oi_init_remote_parent(env, o);

	rc = osd_oi_init_compat(env, o);
	if (rc)
		RETURN(rc);

	count = osd_oi_probe(env, o);
	if (count < 0)
		GOTO(out, rc = count);

	if (count > 0) {
		if (count == sf->sf_oi_count)
			goto open;

		if (sf->sf_oi_count == 0) {
			if (likely((count & (count - 1)) == 0)) {
				sf->sf_oi_count = count;
				rc = scrub_file_store(env, scrub);
				if (rc)
					GOTO(out, rc);

				goto open;
			}

			LCONSOLE_ERROR("%s: invalid oi count %d. You can "
				       "remove all OIs, then remount it\n",
				       osd_name(o), count);
			GOTO(out, rc = -EDOM);
		}

		scrub_file_reset(scrub, o->od_uuid, SF_RECREATED);
		count = sf->sf_oi_count;
	} else {
		if (sf->sf_oi_count > 0) {
			count = sf->sf_oi_count;
			memset(sf->sf_oi_bitmap, 0, SCRUB_OI_BITMAP_SIZE);
			for (i = 0; i < count; i++)
				zfs_set_bit(i, sf->sf_oi_bitmap);
			scrub_file_reset(scrub, o->od_uuid, SF_RECREATED);
		} else {
			count = sf->sf_oi_count = osd_oi_count;
		}
	}

	rc = scrub_file_store(env, scrub);
	if (rc)
		GOTO(out, rc);

	for (i = 0; i < count; i++) {
		LASSERT(sizeof(osd_oti_get(env)->oti_buf) >= 32);

		snprintf(key, sizeof(osd_oti_get(env)->oti_buf) - 1,
			 "%s.%d", DMU_OSD_OI_NAME_BASE, i);
		rc = osd_oi_find_or_create(env, o, o->od_root, key, &sdb);
		if (rc)
			GOTO(out, rc);
	}

open:
	LASSERT((count & (count - 1)) == 0);
	o->od_oi_count = count;
	OBD_ALLOC(o->od_oi_table, sizeof(struct osd_oi *) * count);
	if (o->od_oi_table == NULL)
		GOTO(out, rc = -ENOMEM);

	rc = osd_oi_open_table(env, o, count);

	GOTO(out, rc);

out:
	if (rc) {
		osd_ost_seq_fini(env, o);

		if (o->od_oi_table) {
			OBD_FREE(o->od_oi_table,
				 sizeof(struct osd_oi *) * count);
			o->od_oi_table = NULL;
		}
	}

	return rc;
}

void osd_oi_fini(const struct lu_env *env, struct osd_device *o)
{
	ENTRY;

	osd_ost_seq_fini(env, o);

	if (o->od_oi_table != NULL) {
		(void) osd_oi_close_table(env, o);
		OBD_FREE(o->od_oi_table,
			 sizeof(struct osd_oi *) * o->od_oi_count);
		o->od_oi_table = NULL;
		o->od_oi_count = 0;
	}

	EXIT;
}

int osd_options_init(void)
{
	/* osd_oi_count - Default number of OIs, 128 works well for ZFS */
	if (osd_oi_count == 0 || osd_oi_count > OSD_OI_FID_NR_MAX)
		osd_oi_count = OSD_OI_FID_NR;

	if ((osd_oi_count & (osd_oi_count - 1)) != 0) {
		LCONSOLE_WARN("Round up osd_oi_count %d to power2 %d\n",
			osd_oi_count, size_roundup_power2(osd_oi_count));
		osd_oi_count = size_roundup_power2(osd_oi_count);
	}

	return 0;
}

/*
 * the following set of functions are used to maintain per-thread
 * cache of FID->ino mapping. this mechanism is used to avoid
 * expensive LU/OI lookups.
 */
struct osd_idmap_cache *osd_idc_find(const struct lu_env *env,
				     struct osd_device *osd,
				     const struct lu_fid *fid)
{
	struct osd_thread_info *oti = osd_oti_get(env);
	struct osd_idmap_cache *idc = oti->oti_ins_cache;
	int i;

	for (i = 0; i < oti->oti_ins_cache_used; i++) {
		if (!lu_fid_eq(&idc[i].oic_fid, fid))
			continue;
		if (idc[i].oic_dev != osd)
			continue;

		return idc + i;
	}

	return NULL;
}

struct osd_idmap_cache *osd_idc_add(const struct lu_env *env,
				    struct osd_device *osd,
				    const struct lu_fid *fid)
{
	struct osd_thread_info *oti = osd_oti_get(env);
	struct osd_idmap_cache *idc;
	int i;

	if (unlikely(oti->oti_ins_cache_used >= oti->oti_ins_cache_size)) {
		i = oti->oti_ins_cache_size * 2;
		LASSERT(i < 1000);
		if (i == 0)
			i = OSD_INS_CACHE_SIZE;
		OBD_ALLOC(idc, sizeof(*idc) * i);
		if (idc == NULL)
			return ERR_PTR(-ENOMEM);
		if (oti->oti_ins_cache != NULL) {
			memcpy(idc, oti->oti_ins_cache,
			       oti->oti_ins_cache_used * sizeof(*idc));
			OBD_FREE(oti->oti_ins_cache,
				 oti->oti_ins_cache_used * sizeof(*idc));
		}
		oti->oti_ins_cache = idc;
		oti->oti_ins_cache_size = i;
	}

	idc = &oti->oti_ins_cache[oti->oti_ins_cache_used++];
	idc->oic_fid = *fid;
	idc->oic_dev = osd;
	idc->oic_dnode = 0;
	idc->oic_remote = 0;

	return idc;
}

/**
 * Lookup mapping for the given fid in the cache
 *
 * Initialize a new one if not found. the initialization checks whether
 * the object is local or remote. for the local objects, OI is used to
 * learn dnode#. the function is used when the caller has no information
 * about the object, e.g. at dt_insert().
 */
struct osd_idmap_cache *osd_idc_find_or_init(const struct lu_env *env,
					     struct osd_device *osd,
					     const struct lu_fid *fid)
{
	struct osd_idmap_cache *idc;
	int rc;

	LASSERT(!fid_is_acct(fid));

	idc = osd_idc_find(env, osd, fid);
	if (idc != NULL)
		return idc;

	CDEBUG(D_INODE, "%s: FID "DFID" not in the id map cache\n",
	       osd->od_svname, PFID(fid));

	/* new mapping is needed */
	idc = osd_idc_add(env, osd, fid);
	if (IS_ERR(idc)) {
		CERROR("%s: FID "DFID" add id map cache failed: %ld\n",
		       osd->od_svname, PFID(fid), PTR_ERR(idc));
		return idc;
	}

	/* initialize it */
	rc = osd_remote_fid(env, osd, fid);
	if (unlikely(rc < 0))
		return ERR_PTR(rc);

	if (rc == 0) {
		/* the object is local, lookup in OI */
		uint64_t dnode;

		rc = osd_fid_lookup(env, osd, fid, &dnode);
		if (unlikely(rc < 0)) {
			CERROR("%s: can't lookup: rc = %d\n",
			       osd->od_svname, rc);
			return ERR_PTR(rc);
		}
		LASSERT(dnode < (1ULL << DN_MAX_OBJECT_SHIFT));
		idc->oic_dnode = dnode;
	} else {
		/* the object is remote */
		idc->oic_remote = 1;
	}

	return idc;
}

/*
 * lookup mapping for given FID and fill it from the given object.
 * the object is local by definition.
 */
int osd_idc_find_and_init(const struct lu_env *env, struct osd_device *osd,
			  struct osd_object *obj)
{
	const struct lu_fid *fid = lu_object_fid(&obj->oo_dt.do_lu);
	struct osd_idmap_cache *idc;

	idc = osd_idc_find(env, osd, fid);
	if (idc != NULL) {
		if (obj->oo_dn == NULL)
			return 0;
		idc->oic_dnode = obj->oo_dn->dn_object;
		return 0;
	}

	CDEBUG(D_INODE, "%s: FID "DFID" not in the id map cache\n",
	       osd->od_svname, PFID(fid));

	/* new mapping is needed */
	idc = osd_idc_add(env, osd, fid);
	if (IS_ERR(idc)) {
		CERROR("%s: FID "DFID" add id map cache failed: %ld\n",
		       osd->od_svname, PFID(fid), PTR_ERR(idc));
		return PTR_ERR(idc);
	}

	if (obj->oo_dn)
		idc->oic_dnode = obj->oo_dn->dn_object;

	return 0;
}

int osd_idc_find_and_init_with_oid(const struct lu_env *env,
				   struct osd_device *osd,
				   const struct lu_fid *fid,
				   uint64_t oid)
{
	struct osd_idmap_cache *idc;

	idc = osd_idc_find(env, osd, fid);
	if (!idc) {
		idc = osd_idc_add(env, osd, fid);
		if (IS_ERR(idc))
			return PTR_ERR(idc);
	}

	idc->oic_dnode = oid;
	idc->oic_remote = 0;

	return 0;
}