text: // SPDX-License-Identifier: GPL-2.0
  /*
   * 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) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
   * Use is subject to license terms.
   *
   * Copyright (c) 2011, 2015, Intel Corporation.
   */
  /*
   * This file is part of Lustre, http://www.lustre.org/
   * Lustre is a trademark of Sun Microsystems, Inc.
   *
   * lustre/include/lustre_fid.h
   *
   * Author: Yury Umanets <umka@clusterfs.com>
   */
  
  #ifndef __LUSTRE_FID_H
  #define __LUSTRE_FID_H
  
  /** \defgroup fid fid
   *
   * @{
   *
   * http://wiki.lustre.org/index.php/Architecture_-_Interoperability_fids_zfs
   * describes the FID namespace and interoperability requirements for FIDs.
   * The important parts of that document are included here for reference.
   *
   * FID
   *   File IDentifier generated by client from range allocated by the SEQuence
   *   service and stored in struct lu_fid. The FID is composed of three parts:
   *   SEQuence, ObjectID, and VERsion.  The SEQ component is a filesystem
   *   unique 64-bit integer, and only one client is ever assigned any SEQ value.
   *   The first 0x400 FID_SEQ_NORMAL [2^33, 2^33 + 0x400] values are reserved
   *   for system use.  The OID component is a 32-bit value generated by the
   *   client on a per-SEQ basis to allow creating many unique FIDs without
   *   communication with the server.  The VER component is a 32-bit value that
   *   distinguishes between different FID instantiations, such as snapshots or
   *   separate subtrees within the filesystem.  FIDs with the same VER field
   *   are considered part of the same namespace.
   *
   * OLD filesystems are those upgraded from Lustre 1.x that predate FIDs, and
   *   MDTs use 32-bit ldiskfs internal inode/generation numbers (IGIFs), while
   *   OSTs use 64-bit Lustre object IDs and generation numbers.
   *
   * NEW filesystems are those formatted since the introduction of FIDs.
   *
   * IGIF
   *   Inode and Generation In FID, a surrogate FID used to globally identify
   *   an existing object on OLD formatted MDT file system. This would only be
   *   used on MDT0 in a DNE filesystem, because there cannot be more than one
   *   MDT in an OLD formatted filesystem. Belongs to sequence in [12, 2^32 - 1]
   *   range, where inode number is stored in SEQ, and inode generation is in OID.
   *   NOTE: This assumes no more than 2^32-1 inodes exist in the MDT filesystem,
   *   which is the maximum possible for an ldiskfs backend.  It also assumes
   *   that the reserved ext3/ext4/ldiskfs inode numbers [0-11] are never visible
   *   to clients, which has always been true.
   *
   * IDIF
   *   object ID In FID, a surrogate FID used to globally identify an existing
   *   OST object on OLD formatted OST file system. Belongs to a sequence in
   *   [2^32, 2^33 - 1]. Sequence number is calculated as:
   *
   *      1 << 32 | (ost_index << 16) | ((objid >> 32) & 0xffff)
   *
   *   that is, SEQ consists of 16-bit OST index, and higher 16 bits of object
   *   ID. The generation of unique SEQ values per OST allows the IDIF FIDs to
   *   be identified in the FLD correctly. The OID field is calculated as:
   *
   *      objid & 0xffffffff
   *
   *   that is, it consists of lower 32 bits of object ID.  For objects within
   *   the IDIF range, object ID extraction will be:
   *
   *      o_id = (fid->f_seq & 0x7fff) << 16 | fid->f_oid;
   *      o_seq = 0;  // formerly group number
   *
   *   NOTE: This assumes that no more than 2^48-1 objects have ever been created
   *   on any OST, and that no more than 65535 OSTs are in use.  Both are very
   *   reasonable assumptions, i.e. an IDIF can uniquely map all objects assuming
   *   a maximum creation rate of 1M objects per second for a maximum of 9 years,
   *   or combinations thereof.
   *
   * OST_MDT0
   *   Surrogate FID used to identify an existing object on OLD formatted OST
   *   filesystem. Belongs to the reserved SEQuence 0, and is used prior to
   *   the introduction of FID-on-OST, at which point IDIF will be used to
   *   identify objects as residing on a specific OST.
   *
   * LLOG
   *   For Lustre Log objects the object sequence 1 is used. This is compatible
   *   with both OLD and NEW namespaces, as this SEQ number is in the
   *   ext3/ldiskfs reserved inode range and does not conflict with IGIF
   *   sequence numbers.
   *
   * ECHO
   *   For testing OST IO performance the object sequence 2 is used. This is
   *   compatible with both OLD and NEW namespaces, as this SEQ number is in
   *   the ext3/ldiskfs reserved inode range and does not conflict with IGIF
   *   sequence numbers.
   *
   * OST_MDT1 .. OST_MAX
   *   For testing with multiple MDTs the object sequence 3 through 9 is used,
   *   allowing direct mapping of MDTs 1 through 7 respectively, for a total
   *   of 8 MDTs including OST_MDT0. This matches the legacy CMD project "group"
   *   mappings. However, this SEQ range is only for testing prior to any
   *   production DNE release, as the objects in this range conflict across all
   *   OSTs, as the OST index is not part of the FID.  For production DNE usage,
   *   OST objects created by MDT1+ will use FID_SEQ_NORMAL FIDs.
   *
   * DLM OST objid to IDIF mapping
   *   For compatibility with existing OLD OST network protocol structures, the
   *   FID must map onto the o_id and o_seq in a manner that ensures existing
   *   objects are identified consistently for IO, as well as onto the LDLM
   *   namespace to ensure IDIFs there is only a single resource name for any
   *   object in the DLM.  The OLD OST object DLM resource mapping is:
   *
   *      resource[] = {o_id, o_seq, 0, 0}; // o_seq == 0 for production releases
   *
   *   The NEW OST object DLM resource mapping is the same for both MDT and OST:
   *
   *      resource[] = {SEQ, OID, VER, HASH};
   *
   *  NOTE: for mapping IDIF values to DLM resource names the o_id may be
   *  larger than the 2^33 reserved sequence numbers for IDIF, so it is possible
   *  for the o_id numbers to overlap FID SEQ numbers in the resource. However,
   *  in all production releases the OLD o_seq field is always zero, and all
   *  valid FID OID values are non-zero, so the lock resources will not collide.
   *  Even so, the MDT and OST resources are also in different LDLM namespaces.
   */
  
  #include <linux/libcfs/libcfs.h>
  #include <uapi/linux/lustre/lustre_fid.h>
  #include <uapi/linux/lustre/lustre_idl.h>
  #include <uapi/linux/lustre/lustre_ostid.h>
  
  struct lu_env;
  struct lu_site;
  struct lu_context;
  struct obd_device;
  struct obd_export;
  
  /* Whole sequences space range and zero range definitions */
  extern const struct lu_seq_range LUSTRE_SEQ_SPACE_RANGE;
  extern const struct lu_seq_range LUSTRE_SEQ_ZERO_RANGE;
  extern const struct lu_fid LUSTRE_BFL_FID;
  extern const struct lu_fid LU_OBF_FID;
  extern const struct lu_fid LU_DOT_LUSTRE_FID;
  
  enum {
  	/*
  	 * This is how may metadata FIDs may be allocated in one sequence(128k)
  	 */
  	LUSTRE_METADATA_SEQ_MAX_WIDTH = 0x0000000000020000ULL,
  
  	/*
  	 * This is how many data FIDs could be allocated in one sequence(4B - 1)
  	 */
  	LUSTRE_DATA_SEQ_MAX_WIDTH = 0x00000000FFFFFFFFULL,
  
  	/*
  	 * How many sequences to allocate to a client at once.
  	 */
  	LUSTRE_SEQ_META_WIDTH = 0x0000000000000001ULL,
  
  	/*
  	 * seq allocation pool size.
  	 */
  	LUSTRE_SEQ_BATCH_WIDTH = LUSTRE_SEQ_META_WIDTH * 1000,
  
  	/*
  	 * This is how many sequences may be in one super-sequence allocated to
  	 * MDTs.
  	 */
  	LUSTRE_SEQ_SUPER_WIDTH = ((1ULL << 30ULL) * LUSTRE_SEQ_META_WIDTH)
  };
  
  enum {
  	/** 2^6 FIDs for OI containers */
  	OSD_OI_FID_OID_BITS     = 6,
  	/** reserve enough FIDs in case we want more in the future */
  	OSD_OI_FID_OID_BITS_MAX = 10,
  };
  
  /** special OID for local objects */
  enum local_oid {
  	/** \see fld_mod_init */
  	FLD_INDEX_OID		= 3UL,
  	/** \see fid_mod_init */
  	FID_SEQ_CTL_OID		= 4UL,
  	FID_SEQ_SRV_OID		= 5UL,
  	/** \see mdd_mod_init */
  	MDD_ROOT_INDEX_OID	= 6UL, /* deprecated in 2.4 */
  	MDD_ORPHAN_OID		= 7UL, /* deprecated in 2.4 */
  	MDD_LOV_OBJ_OID		= 8UL,
  	MDD_CAPA_KEYS_OID	= 9UL,
  	/** \see mdt_mod_init */
  	LAST_RECV_OID		= 11UL,
  	OSD_FS_ROOT_OID		= 13UL,
  	ACCT_USER_OID		= 15UL,
  	ACCT_GROUP_OID		= 16UL,
  	LFSCK_BOOKMARK_OID	= 17UL,
  	OTABLE_IT_OID		= 18UL,
  	/* These two definitions are obsolete
  	 * OFD_GROUP0_LAST_OID     = 20UL,
  	 * OFD_GROUP4K_LAST_OID    = 20UL+4096,
  	 */
  	OFD_LAST_GROUP_OID	= 4117UL,
  	LLOG_CATALOGS_OID	= 4118UL,
  	MGS_CONFIGS_OID		= 4119UL,
  	OFD_HEALTH_CHECK_OID	= 4120UL,
  	MDD_LOV_OBJ_OSEQ	= 4121UL,
  	LFSCK_NAMESPACE_OID     = 4122UL,
  	REMOTE_PARENT_DIR_OID	= 4123UL,
  	SLAVE_LLOG_CATALOGS_OID	= 4124UL,
  };
  
  static inline void lu_local_obj_fid(struct lu_fid *fid, __u32 oid)
  {
  	fid->f_seq = FID_SEQ_LOCAL_FILE;
  	fid->f_oid = oid;
  	fid->f_ver = 0;
  }
  
  static inline void lu_local_name_obj_fid(struct lu_fid *fid, __u32 oid)
  {
  	fid->f_seq = FID_SEQ_LOCAL_NAME;
  	fid->f_oid = oid;
  	fid->f_ver = 0;
  }
  
  /* For new FS (>= 2.4), the root FID will be changed to
   * [FID_SEQ_ROOT:1:0], for existing FS, (upgraded to 2.4),
   * the root FID will still be IGIF
   */
  static inline int fid_is_root(const struct lu_fid *fid)
  {
  	return unlikely((fid_seq(fid) == FID_SEQ_ROOT &&
  			 fid_oid(fid) == 1));
  }
  
  static inline int fid_is_dot_lustre(const struct lu_fid *fid)
  {
  	return unlikely(fid_seq(fid) == FID_SEQ_DOT_LUSTRE &&
  			fid_oid(fid) == FID_OID_DOT_LUSTRE);
  }
  
  static inline int fid_is_obf(const struct lu_fid *fid)
  {
  	return unlikely(fid_seq(fid) == FID_SEQ_DOT_LUSTRE &&
  			fid_oid(fid) == FID_OID_DOT_LUSTRE_OBF);
  }
  
  static inline int fid_is_otable_it(const struct lu_fid *fid)
  {
  	return unlikely(fid_seq(fid) == FID_SEQ_LOCAL_FILE &&
  			fid_oid(fid) == OTABLE_IT_OID);
  }
  
  static inline int fid_is_acct(const struct lu_fid *fid)
  {
  	return fid_seq(fid) == FID_SEQ_LOCAL_FILE &&
  	       (fid_oid(fid) == ACCT_USER_OID ||
  		fid_oid(fid) == ACCT_GROUP_OID);
  }
  
  static inline int fid_is_quota(const struct lu_fid *fid)
  {
  	return fid_seq(fid) == FID_SEQ_QUOTA ||
  	       fid_seq(fid) == FID_SEQ_QUOTA_GLB;
  }
  
  static inline int fid_seq_in_fldb(__u64 seq)
  {
  	return fid_seq_is_igif(seq) || fid_seq_is_norm(seq) ||
  	       fid_seq_is_root(seq) || fid_seq_is_dot(seq);
  }
  
  static inline void lu_last_id_fid(struct lu_fid *fid, __u64 seq, __u32 ost_idx)
  {
  	if (fid_seq_is_mdt0(seq)) {
  		fid->f_seq = fid_idif_seq(0, ost_idx);
  	} else {
  		LASSERTF(fid_seq_is_norm(seq) || fid_seq_is_echo(seq) ||
  			 fid_seq_is_idif(seq), "%#llx\n", seq);
  		fid->f_seq = seq;
  	}
  	fid->f_oid = 0;
  	fid->f_ver = 0;
  }
  
  /* seq client type */
  enum lu_cli_type {
  	LUSTRE_SEQ_METADATA = 1,
  	LUSTRE_SEQ_DATA
  };
  
  enum lu_mgr_type {
  	LUSTRE_SEQ_SERVER,
  	LUSTRE_SEQ_CONTROLLER
  };
  
  /* Client sequence manager interface. */
  struct lu_client_seq {
  	/* Sequence-controller export. */
  	struct obd_export      *lcs_exp;
  	struct mutex		lcs_mutex;
  
  	/*
  	 * Range of allowed for allocation sequences. When using lu_client_seq on
  	 * clients, this contains meta-sequence range. And for servers this
  	 * contains super-sequence range.
  	 */
  	struct lu_seq_range	 lcs_space;
  
  	/* Seq related proc */
  	struct dentry		*lcs_debugfs_entry;
  
  	/* This holds last allocated fid in last obtained seq */
  	struct lu_fid	   lcs_fid;
  
  	/* LUSTRE_SEQ_METADATA or LUSTRE_SEQ_DATA */
  	enum lu_cli_type	lcs_type;
  
  	/*
  	 * Service uuid, passed from MDT + seq name to form unique seq name to
  	 * use it with procfs.
  	 */
  	char		    lcs_name[LUSTRE_MDT_MAXNAMELEN];
  
  	/*
  	 * Sequence width, that is how many objects may be allocated in one
  	 * sequence. Default value for it is LUSTRE_SEQ_MAX_WIDTH.
  	 */
  	__u64		   lcs_width;
  
  	/* wait queue for fid allocation and update indicator */
  	wait_queue_head_t	     lcs_waitq;
  	int		     lcs_update;
  };
  
  /* Client methods */
  void seq_client_flush(struct lu_client_seq *seq);
  
  int seq_client_alloc_fid(const struct lu_env *env, struct lu_client_seq *seq,
  			 struct lu_fid *fid);
  /* Fids common stuff */
  int fid_is_local(const struct lu_env *env,
  		 struct lu_site *site, const struct lu_fid *fid);
  
  enum lu_cli_type;
  int client_fid_init(struct obd_device *obd, struct obd_export *exp,
  		    enum lu_cli_type type);
  int client_fid_fini(struct obd_device *obd);
  
  /* fid locking */
  
  struct ldlm_namespace;
  
  /*
   * Build (DLM) resource name from FID.
   *
   * NOTE: until Lustre 1.8.7/2.1.1 the fid_ver() was packed into name[2],
   * but was moved into name[1] along with the OID to avoid consuming the
   * renaming name[2,3] fields that need to be used for the quota identifier.
   */
  static inline void
  fid_build_reg_res_name(const struct lu_fid *fid, struct ldlm_res_id *res)
  {
  	memset(res, 0, sizeof(*res));
  	res->name[LUSTRE_RES_ID_SEQ_OFF] = fid_seq(fid);
  	res->name[LUSTRE_RES_ID_VER_OID_OFF] = fid_ver_oid(fid);
  }
  
  /*
   * Return true if resource is for object identified by FID.
   */
  static inline bool fid_res_name_eq(const struct lu_fid *fid,
  				   const struct ldlm_res_id *res)
  {
  	return res->name[LUSTRE_RES_ID_SEQ_OFF] == fid_seq(fid) &&
  	       res->name[LUSTRE_RES_ID_VER_OID_OFF] == fid_ver_oid(fid);
  }
  
  /*
   * Extract FID from LDLM resource. Reverse of fid_build_reg_res_name().
   */
  static inline void
  fid_extract_from_res_name(struct lu_fid *fid, const struct ldlm_res_id *res)
  {
  	fid->f_seq = res->name[LUSTRE_RES_ID_SEQ_OFF];
  	fid->f_oid = (__u32)(res->name[LUSTRE_RES_ID_VER_OID_OFF]);
  	fid->f_ver = (__u32)(res->name[LUSTRE_RES_ID_VER_OID_OFF] >> 32);
  	LASSERT(fid_res_name_eq(fid, res));
  }
  
  /*
   * Build (DLM) resource identifier from global quota FID and quota ID.
   */
  static inline void
  fid_build_quota_res_name(const struct lu_fid *glb_fid, union lquota_id *qid,
  			 struct ldlm_res_id *res)
  {
  	fid_build_reg_res_name(glb_fid, res);
  	res->name[LUSTRE_RES_ID_QUOTA_SEQ_OFF] = fid_seq(&qid->qid_fid);
  	res->name[LUSTRE_RES_ID_QUOTA_VER_OID_OFF] = fid_ver_oid(&qid->qid_fid);
  }
  
  /*
   * Extract global FID and quota ID from resource name
   */
  static inline void fid_extract_from_quota_res(struct lu_fid *glb_fid,
  					      union lquota_id *qid,
  					      const struct ldlm_res_id *res)
  {
  	fid_extract_from_res_name(glb_fid, res);
  	qid->qid_fid.f_seq = res->name[LUSTRE_RES_ID_QUOTA_SEQ_OFF];
  	qid->qid_fid.f_oid = (__u32)res->name[LUSTRE_RES_ID_QUOTA_VER_OID_OFF];
  	qid->qid_fid.f_ver =
  		(__u32)(res->name[LUSTRE_RES_ID_QUOTA_VER_OID_OFF] >> 32);
  }
  
  static inline void
  fid_build_pdo_res_name(const struct lu_fid *fid, unsigned int hash,
  		       struct ldlm_res_id *res)
  {
  	fid_build_reg_res_name(fid, res);
  	res->name[LUSTRE_RES_ID_HSH_OFF] = hash;
  }
  
  /**
   * Build DLM resource name from object id & seq, which will be removed
   * finally, when we replace ost_id with FID in data stack.
   *
   * Currently, resid from the old client, whose res[0] = object_id,
   * res[1] = object_seq, is just opposite with Metatdata
   * resid, where, res[0] = fid->f_seq, res[1] = fid->f_oid.
   * To unify the resid identification, we will reverse the data
   * resid to keep it same with Metadata resid, i.e.
   *
   * For resid from the old client,
   *    res[0] = objid,  res[1] = 0, still keep the original order,
   *    for compatibility.
   *
   * For new resid
   *    res will be built from normal FID directly, i.e. res[0] = f_seq,
   *    res[1] = f_oid + f_ver.
   */
  static inline void ostid_build_res_name(const struct ost_id *oi,
  					struct ldlm_res_id *name)
  {
  	memset(name, 0, sizeof(*name));
  	if (fid_seq_is_mdt0(ostid_seq(oi))) {
  		name->name[LUSTRE_RES_ID_SEQ_OFF] = ostid_id(oi);
  		name->name[LUSTRE_RES_ID_VER_OID_OFF] = ostid_seq(oi);
  	} else {
  		fid_build_reg_res_name(&oi->oi_fid, name);
  	}
  }
  
  /**
   * Return true if the resource is for the object identified by this id & group.
   */
  static inline int ostid_res_name_eq(const struct ost_id *oi,
  				    const struct ldlm_res_id *name)
  {
  	/* Note: it is just a trick here to save some effort, probably the
  	 * correct way would be turn them into the FID and compare
  	 */
  	if (fid_seq_is_mdt0(ostid_seq(oi))) {
  		return name->name[LUSTRE_RES_ID_SEQ_OFF] == ostid_id(oi) &&
  		       name->name[LUSTRE_RES_ID_VER_OID_OFF] == ostid_seq(oi);
  	} else {
  		return name->name[LUSTRE_RES_ID_SEQ_OFF] == ostid_seq(oi) &&
  		       name->name[LUSTRE_RES_ID_VER_OID_OFF] == ostid_id(oi);
  	}
  }
  
  /**
   * Note: we need check oi_seq to decide where to set oi_id,
   * so oi_seq should always be set ahead of oi_id.
   */
  static inline int ostid_set_id(struct ost_id *oi, __u64 oid)
  {
  	if (fid_seq_is_mdt0(oi->oi.oi_seq)) {
  		if (oid >= IDIF_MAX_OID)
  			return -E2BIG;
  		oi->oi.oi_id = oid;
  	} else if (fid_is_idif(&oi->oi_fid)) {
  		if (oid >= IDIF_MAX_OID)
  			return -E2BIG;
  		oi->oi_fid.f_seq = fid_idif_seq(oid,
  						fid_idif_ost_idx(&oi->oi_fid));
  		oi->oi_fid.f_oid = oid;
  		oi->oi_fid.f_ver = oid >> 48;
  	} else {
  		if (oid >= OBIF_MAX_OID)
  			return -E2BIG;
  		oi->oi_fid.f_oid = oid;
  	}
  	return 0;
  }
  
  /* pack any OST FID into an ostid (id/seq) for the wire/disk */
  static inline int fid_to_ostid(const struct lu_fid *fid, struct ost_id *ostid)
  {
  	int rc = 0;
  
  	if (fid_seq_is_igif(fid->f_seq))
  		return -EBADF;
  
  	if (fid_is_idif(fid)) {
  		u64 objid = fid_idif_id(fid_seq(fid), fid_oid(fid),
  					fid_ver(fid));
  
  		ostid_set_seq_mdt0(ostid);
  		rc = ostid_set_id(ostid, objid);
  	} else {
  		ostid->oi_fid = *fid;
  	}
  
  	return rc;
  }
  
  /* The same as osc_build_res_name() */
  static inline void ost_fid_build_resid(const struct lu_fid *fid,
  				       struct ldlm_res_id *resname)
  {
  	if (fid_is_mdt0(fid) || fid_is_idif(fid)) {
  		struct ost_id oi;
  
  		oi.oi.oi_id = 0; /* gcc 4.7.2 complains otherwise */
  		if (fid_to_ostid(fid, &oi) != 0)
  			return;
  		ostid_build_res_name(&oi, resname);
  	} else {
  		fid_build_reg_res_name(fid, resname);
  	}
  }
  
  /**
   * Flatten 128-bit FID values into a 64-bit value for use as an inode number.
   * For non-IGIF FIDs this starts just over 2^32, and continues without
   * conflict until 2^64, at which point we wrap the high 24 bits of the SEQ
   * into the range where there may not be many OID values in use, to minimize
   * the risk of conflict.
   *
   * Suppose LUSTRE_SEQ_MAX_WIDTH less than (1 << 24) which is currently true,
   * the time between re-used inode numbers is very long - 2^40 SEQ numbers,
   * or about 2^40 client mounts, if clients create less than 2^24 files/mount.
   */
  static inline __u64 fid_flatten(const struct lu_fid *fid)
  {
  	__u64 ino;
  	__u64 seq;
  
  	if (fid_is_igif(fid)) {
  		ino = lu_igif_ino(fid);
  		return ino;
  	}
  
  	seq = fid_seq(fid);
  
  	ino = (seq << 24) + ((seq >> 24) & 0xffffff0000ULL) + fid_oid(fid);
  
  	return ino ? ino : fid_oid(fid);
  }
  
  static inline __u32 fid_hash(const struct lu_fid *f, int bits)
  {
  	/* all objects with same id and different versions will belong to same
  	 * collisions list.
  	 */
  	return hash_long(fid_flatten(f), bits);
  }
  
  /**
   * map fid to 32 bit value for ino on 32bit systems.
   */
  static inline __u32 fid_flatten32(const struct lu_fid *fid)
  {
  	__u32 ino;
  	__u64 seq;
  
  	if (fid_is_igif(fid)) {
  		ino = lu_igif_ino(fid);
  		return ino;
  	}
  
  	seq = fid_seq(fid) - FID_SEQ_START;
  
  	/* Map the high bits of the OID into higher bits of the inode number so
  	 * that inodes generated at about the same time have a reduced chance
  	 * of collisions. This will give a period of 2^12 = 1024 unique clients
  	 * (from SEQ) and up to min(LUSTRE_SEQ_MAX_WIDTH, 2^20) = 128k objects
  	 * (from OID), or up to 128M inodes without collisions for new files.
  	 */
  	ino = ((seq & 0x000fffffULL) << 12) + ((seq >> 8) & 0xfffff000) +
  	       (seq >> (64 - (40 - 8)) & 0xffffff00) +
  	       (fid_oid(fid) & 0xff000fff) + ((fid_oid(fid) & 0x00fff000) << 8);
  
  	return ino ? ino : fid_oid(fid);
  }
  
  static inline int lu_fid_diff(const struct lu_fid *fid1,
  			      const struct lu_fid *fid2)
  {
  	LASSERTF(fid_seq(fid1) == fid_seq(fid2), "fid1:" DFID ", fid2:" DFID "\n",
  		 PFID(fid1), PFID(fid2));
  
  	if (fid_is_idif(fid1) && fid_is_idif(fid2))
  		return fid_idif_id(fid1->f_seq, fid1->f_oid, fid1->f_ver) -
  		       fid_idif_id(fid2->f_seq, fid2->f_oid, fid2->f_ver);
  
  	return fid_oid(fid1) - fid_oid(fid2);
  }
  
  #define LUSTRE_SEQ_SRV_NAME "seq_srv"
  #define LUSTRE_SEQ_CTL_NAME "seq_ctl"
  
  /* Range common stuff */
  static inline void range_cpu_to_le(struct lu_seq_range *dst, const struct lu_seq_range *src)
  {
  	dst->lsr_start = cpu_to_le64(src->lsr_start);
  	dst->lsr_end = cpu_to_le64(src->lsr_end);
  	dst->lsr_index = cpu_to_le32(src->lsr_index);
  	dst->lsr_flags = cpu_to_le32(src->lsr_flags);
  }
  
  static inline void range_le_to_cpu(struct lu_seq_range *dst, const struct lu_seq_range *src)
  {
  	dst->lsr_start = le64_to_cpu(src->lsr_start);
  	dst->lsr_end = le64_to_cpu(src->lsr_end);
  	dst->lsr_index = le32_to_cpu(src->lsr_index);
  	dst->lsr_flags = le32_to_cpu(src->lsr_flags);
  }
  
  static inline void range_cpu_to_be(struct lu_seq_range *dst, const struct lu_seq_range *src)
  {
  	dst->lsr_start = cpu_to_be64(src->lsr_start);
  	dst->lsr_end = cpu_to_be64(src->lsr_end);
  	dst->lsr_index = cpu_to_be32(src->lsr_index);
  	dst->lsr_flags = cpu_to_be32(src->lsr_flags);
  }
  
  static inline void range_be_to_cpu(struct lu_seq_range *dst, const struct lu_seq_range *src)
  {
  	dst->lsr_start = be64_to_cpu(src->lsr_start);
  	dst->lsr_end = be64_to_cpu(src->lsr_end);
  	dst->lsr_index = be32_to_cpu(src->lsr_index);
  	dst->lsr_flags = be32_to_cpu(src->lsr_flags);
  }
  
  /** @} fid */
  
  #endif /* __LUSTRE_FID_H */
  