text: /*
   * 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) 1999, 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/genops.c
   *
   * These are the only exported functions, they provide some generic
   * infrastructure for managing object devices
   */
  
  #define DEBUG_SUBSYSTEM S_CLASS
  #include "../include/obd_class.h"
  #include "../include/lprocfs_status.h"
  
  spinlock_t obd_types_lock;
  
  struct kmem_cache *obd_device_cachep;
  struct kmem_cache *obdo_cachep;
  EXPORT_SYMBOL(obdo_cachep);
  static struct kmem_cache *import_cachep;
  
  static struct list_head      obd_zombie_imports;
  static struct list_head      obd_zombie_exports;
  static spinlock_t  obd_zombie_impexp_lock;
  static void obd_zombie_impexp_notify(void);
  static void obd_zombie_export_add(struct obd_export *exp);
  static void obd_zombie_import_add(struct obd_import *imp);
  static void print_export_data(struct obd_export *exp,
  			      const char *status, int locks);
  
  int (*ptlrpc_put_connection_superhack)(struct ptlrpc_connection *c);
  EXPORT_SYMBOL(ptlrpc_put_connection_superhack);
  
  /*
   * support functions: we could use inter-module communication, but this
   * is more portable to other OS's
   */
  static struct obd_device *obd_device_alloc(void)
  {
  	struct obd_device *obd;
  
  	OBD_SLAB_ALLOC_PTR_GFP(obd, obd_device_cachep, GFP_NOFS);
  	if (obd != NULL) {
  		obd->obd_magic = OBD_DEVICE_MAGIC;
  	}
  	return obd;
  }
  
  static void obd_device_free(struct obd_device *obd)
  {
  	LASSERT(obd != NULL);
  	LASSERTF(obd->obd_magic == OBD_DEVICE_MAGIC, "obd %p obd_magic %08x != %08x\n",
  		 obd, obd->obd_magic, OBD_DEVICE_MAGIC);
  	if (obd->obd_namespace != NULL) {
  		CERROR("obd %p: namespace %p was not properly cleaned up (obd_force=%d)!\n",
  		       obd, obd->obd_namespace, obd->obd_force);
  		LBUG();
  	}
  	lu_ref_fini(&obd->obd_reference);
  	OBD_SLAB_FREE_PTR(obd, obd_device_cachep);
  }
  
  struct obd_type *class_search_type(const char *name)
  {
  	struct list_head *tmp;
  	struct obd_type *type;
  
  	spin_lock(&obd_types_lock);
  	list_for_each(tmp, &obd_types) {
  		type = list_entry(tmp, struct obd_type, typ_chain);
  		if (strcmp(type->typ_name, name) == 0) {
  			spin_unlock(&obd_types_lock);
  			return type;
  		}
  	}
  	spin_unlock(&obd_types_lock);
  	return NULL;
  }
  EXPORT_SYMBOL(class_search_type);
  
  struct obd_type *class_get_type(const char *name)
  {
  	struct obd_type *type = class_search_type(name);
  
  	if (!type) {
  		const char *modname = name;
  
  		if (strcmp(modname, "obdfilter") == 0)
  			modname = "ofd";
  
  		if (strcmp(modname, LUSTRE_LWP_NAME) == 0)
  			modname = LUSTRE_OSP_NAME;
  
  		if (!strncmp(modname, LUSTRE_MDS_NAME, strlen(LUSTRE_MDS_NAME)))
  			modname = LUSTRE_MDT_NAME;
  
  		if (!request_module("%s", modname)) {
  			CDEBUG(D_INFO, "Loaded module '%s'\n", modname);
  			type = class_search_type(name);
  		} else {
  			LCONSOLE_ERROR_MSG(0x158, "Can't load module '%s'\n",
  					   modname);
  		}
  	}
  	if (type) {
  		spin_lock(&type->obd_type_lock);
  		type->typ_refcnt++;
  		try_module_get(type->typ_dt_ops->o_owner);
  		spin_unlock(&type->obd_type_lock);
  	}
  	return type;
  }
  EXPORT_SYMBOL(class_get_type);
  
  void class_put_type(struct obd_type *type)
  {
  	LASSERT(type);
  	spin_lock(&type->obd_type_lock);
  	type->typ_refcnt--;
  	module_put(type->typ_dt_ops->o_owner);
  	spin_unlock(&type->obd_type_lock);
  }
  EXPORT_SYMBOL(class_put_type);
  
  #define CLASS_MAX_NAME 1024
  
  int class_register_type(struct obd_ops *dt_ops, struct md_ops *md_ops,
  			struct lprocfs_vars *vars, const char *name,
  			struct lu_device_type *ldt)
  {
  	struct obd_type *type;
  	int rc = 0;
  
  	/* sanity check */
  	LASSERT(strnlen(name, CLASS_MAX_NAME) < CLASS_MAX_NAME);
  
  	if (class_search_type(name)) {
  		CDEBUG(D_IOCTL, "Type %s already registered\n", name);
  		return -EEXIST;
  	}
  
  	rc = -ENOMEM;
  	OBD_ALLOC(type, sizeof(*type));
  	if (type == NULL)
  		return rc;
  
  	OBD_ALLOC_PTR(type->typ_dt_ops);
  	OBD_ALLOC_PTR(type->typ_md_ops);
  	OBD_ALLOC(type->typ_name, strlen(name) + 1);
  
  	if (type->typ_dt_ops == NULL ||
  	    type->typ_md_ops == NULL ||
  	    type->typ_name == NULL)
  		goto failed;
  
  	*(type->typ_dt_ops) = *dt_ops;
  	/* md_ops is optional */
  	if (md_ops)
  		*(type->typ_md_ops) = *md_ops;
  	strcpy(type->typ_name, name);
  	spin_lock_init(&type->obd_type_lock);
  
  	type->typ_procroot = lprocfs_register(type->typ_name, proc_lustre_root,
  					      vars, type);
  	if (IS_ERR(type->typ_procroot)) {
  		rc = PTR_ERR(type->typ_procroot);
  		type->typ_procroot = NULL;
  		goto failed;
  	}
  
  	if (ldt != NULL) {
  		type->typ_lu = ldt;
  		rc = lu_device_type_init(ldt);
  		if (rc != 0)
  			goto failed;
  	}
  
  	spin_lock(&obd_types_lock);
  	list_add(&type->typ_chain, &obd_types);
  	spin_unlock(&obd_types_lock);
  
  	return 0;
  
   failed:
  	if (type->typ_name != NULL)
  		OBD_FREE(type->typ_name, strlen(name) + 1);
  	if (type->typ_md_ops != NULL)
  		OBD_FREE_PTR(type->typ_md_ops);
  	if (type->typ_dt_ops != NULL)
  		OBD_FREE_PTR(type->typ_dt_ops);
  	OBD_FREE(type, sizeof(*type));
  	return rc;
  }
  EXPORT_SYMBOL(class_register_type);
  
  int class_unregister_type(const char *name)
  {
  	struct obd_type *type = class_search_type(name);
  
  	if (!type) {
  		CERROR("unknown obd type\n");
  		return -EINVAL;
  	}
  
  	if (type->typ_refcnt) {
  		CERROR("type %s has refcount (%d)\n", name, type->typ_refcnt);
  		/* This is a bad situation, let's make the best of it */
  		/* Remove ops, but leave the name for debugging */
  		OBD_FREE_PTR(type->typ_dt_ops);
  		OBD_FREE_PTR(type->typ_md_ops);
  		return -EBUSY;
  	}
  
  	if (type->typ_procroot) {
  		lprocfs_remove(&type->typ_procroot);
  	}
  
  	if (type->typ_lu)
  		lu_device_type_fini(type->typ_lu);
  
  	spin_lock(&obd_types_lock);
  	list_del(&type->typ_chain);
  	spin_unlock(&obd_types_lock);
  	OBD_FREE(type->typ_name, strlen(name) + 1);
  	if (type->typ_dt_ops != NULL)
  		OBD_FREE_PTR(type->typ_dt_ops);
  	if (type->typ_md_ops != NULL)
  		OBD_FREE_PTR(type->typ_md_ops);
  	OBD_FREE(type, sizeof(*type));
  	return 0;
  } /* class_unregister_type */
  EXPORT_SYMBOL(class_unregister_type);
  
  /**
   * Create a new obd device.
   *
   * Find an empty slot in ::obd_devs[], create a new obd device in it.
   *
   * \param[in] type_name obd device type string.
   * \param[in] name      obd device name.
   *
   * \retval NULL if create fails, otherwise return the obd device
   *	 pointer created.
   */
  struct obd_device *class_newdev(const char *type_name, const char *name)
  {
  	struct obd_device *result = NULL;
  	struct obd_device *newdev;
  	struct obd_type *type = NULL;
  	int i;
  	int new_obd_minor = 0;
  
  	if (strlen(name) >= MAX_OBD_NAME) {
  		CERROR("name/uuid must be < %u bytes long\n", MAX_OBD_NAME);
  		return ERR_PTR(-EINVAL);
  	}
  
  	type = class_get_type(type_name);
  	if (type == NULL){
  		CERROR("OBD: unknown type: %s\n", type_name);
  		return ERR_PTR(-ENODEV);
  	}
  
  	newdev = obd_device_alloc();
  	if (newdev == NULL) {
  		result = ERR_PTR(-ENOMEM);
  		goto out_type;
  	}
  
  	LASSERT(newdev->obd_magic == OBD_DEVICE_MAGIC);
  
  	write_lock(&obd_dev_lock);
  	for (i = 0; i < class_devno_max(); i++) {
  		struct obd_device *obd = class_num2obd(i);
  
  		if (obd && (strcmp(name, obd->obd_name) == 0)) {
  			CERROR("Device %s already exists at %d, won't add\n",
  			       name, i);
  			if (result) {
  				LASSERTF(result->obd_magic == OBD_DEVICE_MAGIC,
  					 "%p obd_magic %08x != %08x\n", result,
  					 result->obd_magic, OBD_DEVICE_MAGIC);
  				LASSERTF(result->obd_minor == new_obd_minor,
  					 "%p obd_minor %d != %d\n", result,
  					 result->obd_minor, new_obd_minor);
  
  				obd_devs[result->obd_minor] = NULL;
  				result->obd_name[0] = '\0';
  			 }
  			result = ERR_PTR(-EEXIST);
  			break;
  		}
  		if (!result && !obd) {
  			result = newdev;
  			result->obd_minor = i;
  			new_obd_minor = i;
  			result->obd_type = type;
  			strncpy(result->obd_name, name,
  				sizeof(result->obd_name) - 1);
  			obd_devs[i] = result;
  		}
  	}
  	write_unlock(&obd_dev_lock);
  
  	if (result == NULL && i >= class_devno_max()) {
  		CERROR("all %u OBD devices used, increase MAX_OBD_DEVICES\n",
  		       class_devno_max());
  		result = ERR_PTR(-EOVERFLOW);
  		goto out;
  	}
  
  	if (IS_ERR(result))
  		goto out;
  
  	CDEBUG(D_IOCTL, "Adding new device %s (%p)\n",
  	       result->obd_name, result);
  
  	return result;
  out:
  	obd_device_free(newdev);
  out_type:
  	class_put_type(type);
  	return result;
  }
  
  void class_release_dev(struct obd_device *obd)
  {
  	struct obd_type *obd_type = obd->obd_type;
  
  	LASSERTF(obd->obd_magic == OBD_DEVICE_MAGIC, "%p obd_magic %08x != %08x\n",
  		 obd, obd->obd_magic, OBD_DEVICE_MAGIC);
  	LASSERTF(obd == obd_devs[obd->obd_minor], "obd %p != obd_devs[%d] %p\n",
  		 obd, obd->obd_minor, obd_devs[obd->obd_minor]);
  	LASSERT(obd_type != NULL);
  
  	CDEBUG(D_INFO, "Release obd device %s at %d obd_type name =%s\n",
  	       obd->obd_name, obd->obd_minor, obd->obd_type->typ_name);
  
  	write_lock(&obd_dev_lock);
  	obd_devs[obd->obd_minor] = NULL;
  	write_unlock(&obd_dev_lock);
  	obd_device_free(obd);
  
  	class_put_type(obd_type);
  }
  
  int class_name2dev(const char *name)
  {
  	int i;
  
  	if (!name)
  		return -1;
  
  	read_lock(&obd_dev_lock);
  	for (i = 0; i < class_devno_max(); i++) {
  		struct obd_device *obd = class_num2obd(i);
  
  		if (obd && strcmp(name, obd->obd_name) == 0) {
  			/* Make sure we finished attaching before we give
  			   out any references */
  			LASSERT(obd->obd_magic == OBD_DEVICE_MAGIC);
  			if (obd->obd_attached) {
  				read_unlock(&obd_dev_lock);
  				return i;
  			}
  			break;
  		}
  	}
  	read_unlock(&obd_dev_lock);
  
  	return -1;
  }
  EXPORT_SYMBOL(class_name2dev);
  
  struct obd_device *class_name2obd(const char *name)
  {
  	int dev = class_name2dev(name);
  
  	if (dev < 0 || dev > class_devno_max())
  		return NULL;
  	return class_num2obd(dev);
  }
  EXPORT_SYMBOL(class_name2obd);
  
  int class_uuid2dev(struct obd_uuid *uuid)
  {
  	int i;
  
  	read_lock(&obd_dev_lock);
  	for (i = 0; i < class_devno_max(); i++) {
  		struct obd_device *obd = class_num2obd(i);
  
  		if (obd && obd_uuid_equals(uuid, &obd->obd_uuid)) {
  			LASSERT(obd->obd_magic == OBD_DEVICE_MAGIC);
  			read_unlock(&obd_dev_lock);
  			return i;
  		}
  	}
  	read_unlock(&obd_dev_lock);
  
  	return -1;
  }
  EXPORT_SYMBOL(class_uuid2dev);
  
  struct obd_device *class_uuid2obd(struct obd_uuid *uuid)
  {
  	int dev = class_uuid2dev(uuid);
  	if (dev < 0)
  		return NULL;
  	return class_num2obd(dev);
  }
  EXPORT_SYMBOL(class_uuid2obd);
  
  /**
   * Get obd device from ::obd_devs[]
   *
   * \param num [in] array index
   *
   * \retval NULL if ::obd_devs[\a num] does not contains an obd device
   *	 otherwise return the obd device there.
   */
  struct obd_device *class_num2obd(int num)
  {
  	struct obd_device *obd = NULL;
  
  	if (num < class_devno_max()) {
  		obd = obd_devs[num];
  		if (obd == NULL)
  			return NULL;
  
  		LASSERTF(obd->obd_magic == OBD_DEVICE_MAGIC,
  			 "%p obd_magic %08x != %08x\n",
  			 obd, obd->obd_magic, OBD_DEVICE_MAGIC);
  		LASSERTF(obd->obd_minor == num,
  			 "%p obd_minor %0d != %0d\n",
  			 obd, obd->obd_minor, num);
  	}
  
  	return obd;
  }
  EXPORT_SYMBOL(class_num2obd);
  
  /**
   * Get obd devices count. Device in any
   *    state are counted
   * \retval obd device count
   */
  int get_devices_count(void)
  {
  	int index, max_index = class_devno_max(), dev_count = 0;
  
  	read_lock(&obd_dev_lock);
  	for (index = 0; index <= max_index; index++) {
  		struct obd_device *obd = class_num2obd(index);
  		if (obd != NULL)
  			dev_count++;
  	}
  	read_unlock(&obd_dev_lock);
  
  	return dev_count;
  }
  EXPORT_SYMBOL(get_devices_count);
  
  void class_obd_list(void)
  {
  	char *status;
  	int i;
  
  	read_lock(&obd_dev_lock);
  	for (i = 0; i < class_devno_max(); i++) {
  		struct obd_device *obd = class_num2obd(i);
  
  		if (obd == NULL)
  			continue;
  		if (obd->obd_stopping)
  			status = "ST";
  		else if (obd->obd_set_up)
  			status = "UP";
  		else if (obd->obd_attached)
  			status = "AT";
  		else
  			status = "--";
  		LCONSOLE(D_CONFIG, "%3d %s %s %s %s %d\n",
  			 i, status, obd->obd_type->typ_name,
  			 obd->obd_name, obd->obd_uuid.uuid,
  			 atomic_read(&obd->obd_refcount));
  	}
  	read_unlock(&obd_dev_lock);
  	return;
  }
  
  /* Search for a client OBD connected to tgt_uuid.  If grp_uuid is
     specified, then only the client with that uuid is returned,
     otherwise any client connected to the tgt is returned. */
  struct obd_device *class_find_client_obd(struct obd_uuid *tgt_uuid,
  					  const char *typ_name,
  					  struct obd_uuid *grp_uuid)
  {
  	int i;
  
  	read_lock(&obd_dev_lock);
  	for (i = 0; i < class_devno_max(); i++) {
  		struct obd_device *obd = class_num2obd(i);
  
  		if (obd == NULL)
  			continue;
  		if ((strncmp(obd->obd_type->typ_name, typ_name,
  			     strlen(typ_name)) == 0)) {
  			if (obd_uuid_equals(tgt_uuid,
  					    &obd->u.cli.cl_target_uuid) &&
  			    ((grp_uuid)? obd_uuid_equals(grp_uuid,
  							 &obd->obd_uuid) : 1)) {
  				read_unlock(&obd_dev_lock);
  				return obd;
  			}
  		}
  	}
  	read_unlock(&obd_dev_lock);
  
  	return NULL;
  }
  EXPORT_SYMBOL(class_find_client_obd);
  
  /* Iterate the obd_device list looking devices have grp_uuid. Start
     searching at *next, and if a device is found, the next index to look
     at is saved in *next. If next is NULL, then the first matching device
     will always be returned. */
  struct obd_device *class_devices_in_group(struct obd_uuid *grp_uuid, int *next)
  {
  	int i;
  
  	if (next == NULL)
  		i = 0;
  	else if (*next >= 0 && *next < class_devno_max())
  		i = *next;
  	else
  		return NULL;
  
  	read_lock(&obd_dev_lock);
  	for (; i < class_devno_max(); i++) {
  		struct obd_device *obd = class_num2obd(i);
  
  		if (obd == NULL)
  			continue;
  		if (obd_uuid_equals(grp_uuid, &obd->obd_uuid)) {
  			if (next != NULL)
  				*next = i+1;
  			read_unlock(&obd_dev_lock);
  			return obd;
  		}
  	}
  	read_unlock(&obd_dev_lock);
  
  	return NULL;
  }
  EXPORT_SYMBOL(class_devices_in_group);
  
  /**
   * to notify sptlrpc log for \a fsname has changed, let every relevant OBD
   * adjust sptlrpc settings accordingly.
   */
  int class_notify_sptlrpc_conf(const char *fsname, int namelen)
  {
  	struct obd_device  *obd;
  	const char	 *type;
  	int		 i, rc = 0, rc2;
  
  	LASSERT(namelen > 0);
  
  	read_lock(&obd_dev_lock);
  	for (i = 0; i < class_devno_max(); i++) {
  		obd = class_num2obd(i);
  
  		if (obd == NULL || obd->obd_set_up == 0 || obd->obd_stopping)
  			continue;
  
  		/* only notify mdc, osc, mdt, ost */
  		type = obd->obd_type->typ_name;
  		if (strcmp(type, LUSTRE_MDC_NAME) != 0 &&
  		    strcmp(type, LUSTRE_OSC_NAME) != 0 &&
  		    strcmp(type, LUSTRE_MDT_NAME) != 0 &&
  		    strcmp(type, LUSTRE_OST_NAME) != 0)
  			continue;
  
  		if (strncmp(obd->obd_name, fsname, namelen))
  			continue;
  
  		class_incref(obd, __func__, obd);
  		read_unlock(&obd_dev_lock);
  		rc2 = obd_set_info_async(NULL, obd->obd_self_export,
  					 sizeof(KEY_SPTLRPC_CONF),
  					 KEY_SPTLRPC_CONF, 0, NULL, NULL);
  		rc = rc ? rc : rc2;
  		class_decref(obd, __func__, obd);
  		read_lock(&obd_dev_lock);
  	}
  	read_unlock(&obd_dev_lock);
  	return rc;
  }
  EXPORT_SYMBOL(class_notify_sptlrpc_conf);
  
  void obd_cleanup_caches(void)
  {
  	if (obd_device_cachep) {
  		kmem_cache_destroy(obd_device_cachep);
  		obd_device_cachep = NULL;
  	}
  	if (obdo_cachep) {
  		kmem_cache_destroy(obdo_cachep);
  		obdo_cachep = NULL;
  	}
  	if (import_cachep) {
  		kmem_cache_destroy(import_cachep);
  		import_cachep = NULL;
  	}
  	if (capa_cachep) {
  		kmem_cache_destroy(capa_cachep);
  		capa_cachep = NULL;
  	}
  }
  
  int obd_init_caches(void)
  {
  	LASSERT(obd_device_cachep == NULL);
  	obd_device_cachep = kmem_cache_create("ll_obd_dev_cache",
  						 sizeof(struct obd_device),
  						 0, 0, NULL);
  	if (!obd_device_cachep)
  		goto out;
  
  	LASSERT(obdo_cachep == NULL);
  	obdo_cachep = kmem_cache_create("ll_obdo_cache", sizeof(struct obdo),
  					   0, 0, NULL);
  	if (!obdo_cachep)
  		goto out;
  
  	LASSERT(import_cachep == NULL);
  	import_cachep = kmem_cache_create("ll_import_cache",
  					     sizeof(struct obd_import),
  					     0, 0, NULL);
  	if (!import_cachep)
  		goto out;
  
  	LASSERT(capa_cachep == NULL);
  	capa_cachep = kmem_cache_create("capa_cache",
  					   sizeof(struct obd_capa), 0, 0, NULL);
  	if (!capa_cachep)
  		goto out;
  
  	return 0;
   out:
  	obd_cleanup_caches();
  	return -ENOMEM;
  
  }
  
  /* map connection to client */
  struct obd_export *class_conn2export(struct lustre_handle *conn)
  {
  	struct obd_export *export;
  
  	if (!conn) {
  		CDEBUG(D_CACHE, "looking for null handle\n");
  		return NULL;
  	}
  
  	if (conn->cookie == -1) {  /* this means assign a new connection */
  		CDEBUG(D_CACHE, "want a new connection\n");
  		return NULL;
  	}
  
  	CDEBUG(D_INFO, "looking for export cookie %#llx\n", conn->cookie);
  	export = class_handle2object(conn->cookie);
  	return export;
  }
  EXPORT_SYMBOL(class_conn2export);
  
  struct obd_device *class_exp2obd(struct obd_export *exp)
  {
  	if (exp)
  		return exp->exp_obd;
  	return NULL;
  }
  EXPORT_SYMBOL(class_exp2obd);
  
  struct obd_device *class_conn2obd(struct lustre_handle *conn)
  {
  	struct obd_export *export;
  	export = class_conn2export(conn);
  	if (export) {
  		struct obd_device *obd = export->exp_obd;
  		class_export_put(export);
  		return obd;
  	}
  	return NULL;
  }
  EXPORT_SYMBOL(class_conn2obd);
  
  struct obd_import *class_exp2cliimp(struct obd_export *exp)
  {
  	struct obd_device *obd = exp->exp_obd;
  	if (obd == NULL)
  		return NULL;
  	return obd->u.cli.cl_import;
  }
  EXPORT_SYMBOL(class_exp2cliimp);
  
  struct obd_import *class_conn2cliimp(struct lustre_handle *conn)
  {
  	struct obd_device *obd = class_conn2obd(conn);
  	if (obd == NULL)
  		return NULL;
  	return obd->u.cli.cl_import;
  }
  EXPORT_SYMBOL(class_conn2cliimp);
  
  /* Export management functions */
  static void class_export_destroy(struct obd_export *exp)
  {
  	struct obd_device *obd = exp->exp_obd;
  
  	LASSERT_ATOMIC_ZERO(&exp->exp_refcount);
  	LASSERT(obd != NULL);
  
  	CDEBUG(D_IOCTL, "destroying export %p/%s for %s\n", exp,
  	       exp->exp_client_uuid.uuid, obd->obd_name);
  
  	/* "Local" exports (lctl, LOV->{mdc,osc}) have no connection. */
  	if (exp->exp_connection)
  		ptlrpc_put_connection_superhack(exp->exp_connection);
  
  	LASSERT(list_empty(&exp->exp_outstanding_replies));
  	LASSERT(list_empty(&exp->exp_uncommitted_replies));
  	LASSERT(list_empty(&exp->exp_req_replay_queue));
  	LASSERT(list_empty(&exp->exp_hp_rpcs));
  	obd_destroy_export(exp);
  	class_decref(obd, "export", exp);
  
  	OBD_FREE_RCU(exp, sizeof(*exp), &exp->exp_handle);
  }
  
  static void export_handle_addref(void *export)
  {
  	class_export_get(export);
  }
  
  static struct portals_handle_ops export_handle_ops = {
  	.hop_addref = export_handle_addref,
  	.hop_free   = NULL,
  };
  
  struct obd_export *class_export_get(struct obd_export *exp)
  {
  	atomic_inc(&exp->exp_refcount);
  	CDEBUG(D_INFO, "GETting export %p : new refcount %d\n", exp,
  	       atomic_read(&exp->exp_refcount));
  	return exp;
  }
  EXPORT_SYMBOL(class_export_get);
  
  void class_export_put(struct obd_export *exp)
  {
  	LASSERT(exp != NULL);
  	LASSERT_ATOMIC_GT_LT(&exp->exp_refcount, 0, LI_POISON);
  	CDEBUG(D_INFO, "PUTting export %p : new refcount %d\n", exp,
  	       atomic_read(&exp->exp_refcount) - 1);
  
  	if (atomic_dec_and_test(&exp->exp_refcount)) {
  		LASSERT(!list_empty(&exp->exp_obd_chain));
  		CDEBUG(D_IOCTL, "final put %p/%s\n",
  		       exp, exp->exp_client_uuid.uuid);
  
  		/* release nid stat refererence */
  		lprocfs_exp_cleanup(exp);
  
  		obd_zombie_export_add(exp);
  	}
  }
  EXPORT_SYMBOL(class_export_put);
  
  /* Creates a new export, adds it to the hash table, and returns a
   * pointer to it. The refcount is 2: one for the hash reference, and
   * one for the pointer returned by this function. */
  struct obd_export *class_new_export(struct obd_device *obd,
  				    struct obd_uuid *cluuid)
  {
  	struct obd_export *export;
  	struct cfs_hash *hash = NULL;
  	int rc = 0;
  
  	OBD_ALLOC_PTR(export);
  	if (!export)
  		return ERR_PTR(-ENOMEM);
  
  	export->exp_conn_cnt = 0;
  	export->exp_lock_hash = NULL;
  	export->exp_flock_hash = NULL;
  	atomic_set(&export->exp_refcount, 2);
  	atomic_set(&export->exp_rpc_count, 0);
  	atomic_set(&export->exp_cb_count, 0);
  	atomic_set(&export->exp_locks_count, 0);
  #if LUSTRE_TRACKS_LOCK_EXP_REFS
  	INIT_LIST_HEAD(&export->exp_locks_list);
  	spin_lock_init(&export->exp_locks_list_guard);
  #endif
  	atomic_set(&export->exp_replay_count, 0);
  	export->exp_obd = obd;
  	INIT_LIST_HEAD(&export->exp_outstanding_replies);
  	spin_lock_init(&export->exp_uncommitted_replies_lock);
  	INIT_LIST_HEAD(&export->exp_uncommitted_replies);
  	INIT_LIST_HEAD(&export->exp_req_replay_queue);
  	INIT_LIST_HEAD(&export->exp_handle.h_link);
  	INIT_LIST_HEAD(&export->exp_hp_rpcs);
  	class_handle_hash(&export->exp_handle, &export_handle_ops);
  	export->exp_last_request_time = get_seconds();
  	spin_lock_init(&export->exp_lock);
  	spin_lock_init(&export->exp_rpc_lock);
  	INIT_HLIST_NODE(&export->exp_uuid_hash);
  	INIT_HLIST_NODE(&export->exp_nid_hash);
  	spin_lock_init(&export->exp_bl_list_lock);
  	INIT_LIST_HEAD(&export->exp_bl_list);
  
  	export->exp_sp_peer = LUSTRE_SP_ANY;
  	export->exp_flvr.sf_rpc = SPTLRPC_FLVR_INVALID;
  	export->exp_client_uuid = *cluuid;
  	obd_init_export(export);
  
  	spin_lock(&obd->obd_dev_lock);
  	/* shouldn't happen, but might race */
  	if (obd->obd_stopping) {
  		rc = -ENODEV;
  		goto exit_unlock;
  	}
  
  	hash = cfs_hash_getref(obd->obd_uuid_hash);
  	if (hash == NULL) {
  		rc = -ENODEV;
  		goto exit_unlock;
  	}
  	spin_unlock(&obd->obd_dev_lock);
  
  	if (!obd_uuid_equals(cluuid, &obd->obd_uuid)) {
  		rc = cfs_hash_add_unique(hash, cluuid, &export->exp_uuid_hash);
  		if (rc != 0) {
  			LCONSOLE_WARN("%s: denying duplicate export for %s, %d\n",
  				      obd->obd_name, cluuid->uuid, rc);
  			rc = -EALREADY;
  			goto exit_err;
  		}
  	}
  
  	spin_lock(&obd->obd_dev_lock);
  	if (obd->obd_stopping) {
  		cfs_hash_del(hash, cluuid, &export->exp_uuid_hash);
  		rc = -ENODEV;
  		goto exit_unlock;
  	}
  
  	class_incref(obd, "export", export);
  	list_add(&export->exp_obd_chain, &export->exp_obd->obd_exports);
  	list_add_tail(&export->exp_obd_chain_timed,
  			  &export->exp_obd->obd_exports_timed);
  	export->exp_obd->obd_num_exports++;
  	spin_unlock(&obd->obd_dev_lock);
  	cfs_hash_putref(hash);
  	return export;
  
  exit_unlock:
  	spin_unlock(&obd->obd_dev_lock);
  exit_err:
  	if (hash)
  		cfs_hash_putref(hash);
  	class_handle_unhash(&export->exp_handle);
  	LASSERT(hlist_unhashed(&export->exp_uuid_hash));
  	obd_destroy_export(export);
  	OBD_FREE_PTR(export);
  	return ERR_PTR(rc);
  }
  EXPORT_SYMBOL(class_new_export);
  
  void class_unlink_export(struct obd_export *exp)
  {
  	class_handle_unhash(&exp->exp_handle);
  
  	spin_lock(&exp->exp_obd->obd_dev_lock);
  	/* delete an uuid-export hashitem from hashtables */
  	if (!hlist_unhashed(&exp->exp_uuid_hash))
  		cfs_hash_del(exp->exp_obd->obd_uuid_hash,
  			     &exp->exp_client_uuid,
  			     &exp->exp_uuid_hash);
  
  	list_move(&exp->exp_obd_chain, &exp->exp_obd->obd_unlinked_exports);
  	list_del_init(&exp->exp_obd_chain_timed);
  	exp->exp_obd->obd_num_exports--;
  	spin_unlock(&exp->exp_obd->obd_dev_lock);
  	class_export_put(exp);
  }
  EXPORT_SYMBOL(class_unlink_export);
  
  /* Import management functions */
  static void class_import_destroy(struct obd_import *imp)
  {
  	CDEBUG(D_IOCTL, "destroying import %p for %s\n", imp,
  		imp->imp_obd->obd_name);
  
  	LASSERT_ATOMIC_ZERO(&imp->imp_refcount);
  
  	ptlrpc_put_connection_superhack(imp->imp_connection);
  
  	while (!list_empty(&imp->imp_conn_list)) {
  		struct obd_import_conn *imp_conn;
  
  		imp_conn = list_entry(imp->imp_conn_list.next,
  					  struct obd_import_conn, oic_item);
  		list_del_init(&imp_conn->oic_item);
  		ptlrpc_put_connection_superhack(imp_conn->oic_conn);
  		OBD_FREE(imp_conn, sizeof(*imp_conn));
  	}
  
  	LASSERT(imp->imp_sec == NULL);
  	class_decref(imp->imp_obd, "import", imp);
  	OBD_FREE_RCU(imp, sizeof(*imp), &imp->imp_handle);
  }
  
  static void import_handle_addref(void *import)
  {
  	class_import_get(import);
  }
  
  static struct portals_handle_ops import_handle_ops = {
  	.hop_addref = import_handle_addref,
  	.hop_free   = NULL,
  };
  
  struct obd_import *class_import_get(struct obd_import *import)
  {
  	atomic_inc(&import->imp_refcount);
  	CDEBUG(D_INFO, "import %p refcount=%d obd=%s\n", import,
  	       atomic_read(&import->imp_refcount),
  	       import->imp_obd->obd_name);
  	return import;
  }
  EXPORT_SYMBOL(class_import_get);
  
  void class_import_put(struct obd_import *imp)
  {
  	LASSERT(list_empty(&imp->imp_zombie_chain));
  	LASSERT_ATOMIC_GT_LT(&imp->imp_refcount, 0, LI_POISON);
  
  	CDEBUG(D_INFO, "import %p refcount=%d obd=%s\n", imp,
  	       atomic_read(&imp->imp_refcount) - 1,
  	       imp->imp_obd->obd_name);
  
  	if (atomic_dec_and_test(&imp->imp_refcount)) {
  		CDEBUG(D_INFO, "final put import %p\n", imp);
  		obd_zombie_import_add(imp);
  	}
  
  	/* catch possible import put race */
  	LASSERT_ATOMIC_GE_LT(&imp->imp_refcount, 0, LI_POISON);
  }
  EXPORT_SYMBOL(class_import_put);
  
  static void init_imp_at(struct imp_at *at) {
  	int i;
  	at_init(&at->iat_net_latency, 0, 0);
  	for (i = 0; i < IMP_AT_MAX_PORTALS; i++) {
  		/* max service estimates are tracked on the server side, so
  		   don't use the AT history here, just use the last reported
  		   val. (But keep hist for proc histogram, worst_ever) */
  		at_init(&at->iat_service_estimate[i], INITIAL_CONNECT_TIMEOUT,
  			AT_FLG_NOHIST);
  	}
  }
  
  struct obd_import *class_new_import(struct obd_device *obd)
  {
  	struct obd_import *imp;
  
  	OBD_ALLOC(imp, sizeof(*imp));
  	if (imp == NULL)
  		return NULL;
  
  	INIT_LIST_HEAD(&imp->imp_pinger_chain);
  	INIT_LIST_HEAD(&imp->imp_zombie_chain);
  	INIT_LIST_HEAD(&imp->imp_replay_list);
  	INIT_LIST_HEAD(&imp->imp_sending_list);
  	INIT_LIST_HEAD(&imp->imp_delayed_list);
  	INIT_LIST_HEAD(&imp->imp_committed_list);
  	imp->imp_replay_cursor = &imp->imp_committed_list;
  	spin_lock_init(&imp->imp_lock);
  	imp->imp_last_success_conn = 0;
  	imp->imp_state = LUSTRE_IMP_NEW;
  	imp->imp_obd = class_incref(obd, "import", imp);
  	mutex_init(&imp->imp_sec_mutex);
  	init_waitqueue_head(&imp->imp_recovery_waitq);
  
  	atomic_set(&imp->imp_refcount, 2);
  	atomic_set(&imp->imp_unregistering, 0);
  	atomic_set(&imp->imp_inflight, 0);
  	atomic_set(&imp->imp_replay_inflight, 0);
  	atomic_set(&imp->imp_inval_count, 0);
  	INIT_LIST_HEAD(&imp->imp_conn_list);
  	INIT_LIST_HEAD(&imp->imp_handle.h_link);
  	class_handle_hash(&imp->imp_handle, &import_handle_ops);
  	init_imp_at(&imp->imp_at);
  
  	/* the default magic is V2, will be used in connect RPC, and
  	 * then adjusted according to the flags in request/reply. */
  	imp->imp_msg_magic = LUSTRE_MSG_MAGIC_V2;
  
  	return imp;
  }
  EXPORT_SYMBOL(class_new_import);
  
  void class_destroy_import(struct obd_import *import)
  {
  	LASSERT(import != NULL);
  	LASSERT(import != LP_POISON);
  
  	class_handle_unhash(&import->imp_handle);
  
  	spin_lock(&import->imp_lock);
  	import->imp_generation++;
  	spin_unlock(&import->imp_lock);
  	class_import_put(import);
  }
  EXPORT_SYMBOL(class_destroy_import);
  
  #if LUSTRE_TRACKS_LOCK_EXP_REFS
  
  void __class_export_add_lock_ref(struct obd_export *exp, struct ldlm_lock *lock)
  {
  	spin_lock(&exp->exp_locks_list_guard);
  
  	LASSERT(lock->l_exp_refs_nr >= 0);
  
  	if (lock->l_exp_refs_target != NULL &&
  	    lock->l_exp_refs_target != exp) {
  		LCONSOLE_WARN("setting export %p for lock %p which already has export %p\n",
  			      exp, lock, lock->l_exp_refs_target);
  	}
  	if ((lock->l_exp_refs_nr ++) == 0) {
  		list_add(&lock->l_exp_refs_link, &exp->exp_locks_list);
  		lock->l_exp_refs_target = exp;
  	}
  	CDEBUG(D_INFO, "lock = %p, export = %p, refs = %u\n",
  	       lock, exp, lock->l_exp_refs_nr);
  	spin_unlock(&exp->exp_locks_list_guard);
  }
  EXPORT_SYMBOL(__class_export_add_lock_ref);
  
  void __class_export_del_lock_ref(struct obd_export *exp, struct ldlm_lock *lock)
  {
  	spin_lock(&exp->exp_locks_list_guard);
  	LASSERT(lock->l_exp_refs_nr > 0);
  	if (lock->l_exp_refs_target != exp) {
  		LCONSOLE_WARN("lock %p, mismatching export pointers: %p, %p\n",
  			      lock, lock->l_exp_refs_target, exp);
  	}
  	if (-- lock->l_exp_refs_nr == 0) {
  		list_del_init(&lock->l_exp_refs_link);
  		lock->l_exp_refs_target = NULL;
  	}
  	CDEBUG(D_INFO, "lock = %p, export = %p, refs = %u\n",
  	       lock, exp, lock->l_exp_refs_nr);
  	spin_unlock(&exp->exp_locks_list_guard);
  }
  EXPORT_SYMBOL(__class_export_del_lock_ref);
  #endif
  
  /* A connection defines an export context in which preallocation can
     be managed. This releases the export pointer reference, and returns
     the export handle, so the export refcount is 1 when this function
     returns. */
  int class_connect(struct lustre_handle *conn, struct obd_device *obd,
  		  struct obd_uuid *cluuid)
  {
  	struct obd_export *export;
  	LASSERT(conn != NULL);
  	LASSERT(obd != NULL);
  	LASSERT(cluuid != NULL);
  
  	export = class_new_export(obd, cluuid);
  	if (IS_ERR(export))
  		return PTR_ERR(export);
  
  	conn->cookie = export->exp_handle.h_cookie;
  	class_export_put(export);
  
  	CDEBUG(D_IOCTL, "connect: client %s, cookie %#llx\n",
  	       cluuid->uuid, conn->cookie);
  	return 0;
  }
  EXPORT_SYMBOL(class_connect);
  
  /* if export is involved in recovery then clean up related things */
  static void class_export_recovery_cleanup(struct obd_export *exp)
  {
  	struct obd_device *obd = exp->exp_obd;
  
  	spin_lock(&obd->obd_recovery_task_lock);
  	if (exp->exp_delayed)
  		obd->obd_delayed_clients--;
  	if (obd->obd_recovering) {
  		if (exp->exp_in_recovery) {
  			spin_lock(&exp->exp_lock);
  			exp->exp_in_recovery = 0;
  			spin_unlock(&exp->exp_lock);
  			LASSERT_ATOMIC_POS(&obd->obd_connected_clients);
  			atomic_dec(&obd->obd_connected_clients);
  		}
  
  		/* if called during recovery then should update
  		 * obd_stale_clients counter,
  		 * lightweight exports are not counted */
  		if (exp->exp_failed &&
  		    (exp_connect_flags(exp) & OBD_CONNECT_LIGHTWEIGHT) == 0)
  			exp->exp_obd->obd_stale_clients++;
  	}
  	spin_unlock(&obd->obd_recovery_task_lock);
  
  	spin_lock(&exp->exp_lock);
  	/** Cleanup req replay fields */
  	if (exp->exp_req_replay_needed) {
  		exp->exp_req_replay_needed = 0;
  
  		LASSERT(atomic_read(&obd->obd_req_replay_clients));
  		atomic_dec(&obd->obd_req_replay_clients);
  	}
  
  	/** Cleanup lock replay data */
  	if (exp->exp_lock_replay_needed) {
  		exp->exp_lock_replay_needed = 0;
  
  		LASSERT(atomic_read(&obd->obd_lock_replay_clients));
  		atomic_dec(&obd->obd_lock_replay_clients);
  	}
  	spin_unlock(&exp->exp_lock);
  }
  
  /* This function removes 1-3 references from the export:
   * 1 - for export pointer passed
   * and if disconnect really need
   * 2 - removing from hash
   * 3 - in client_unlink_export
   * The export pointer passed to this function can destroyed */
  int class_disconnect(struct obd_export *export)
  {
  	int already_disconnected;
  
  	if (export == NULL) {
  		CWARN("attempting to free NULL export %p\n", export);
  		return -EINVAL;
  	}
  
  	spin_lock(&export->exp_lock);
  	already_disconnected = export->exp_disconnected;
  	export->exp_disconnected = 1;
  	spin_unlock(&export->exp_lock);
  
  	/* class_cleanup(), abort_recovery(), and class_fail_export()
  	 * all end up in here, and if any of them race we shouldn't
  	 * call extra class_export_puts(). */
  	if (already_disconnected) {
  		LASSERT(hlist_unhashed(&export->exp_nid_hash));
  		goto no_disconn;
  	}
  
  	CDEBUG(D_IOCTL, "disconnect: cookie %#llx\n",
  	       export->exp_handle.h_cookie);
  
  	if (!hlist_unhashed(&export->exp_nid_hash))
  		cfs_hash_del(export->exp_obd->obd_nid_hash,
  			     &export->exp_connection->c_peer.nid,
  			     &export->exp_nid_hash);
  
  	class_export_recovery_cleanup(export);
  	class_unlink_export(export);
  no_disconn:
  	class_export_put(export);
  	return 0;
  }
  EXPORT_SYMBOL(class_disconnect);
  
  /* Return non-zero for a fully connected export */
  int class_connected_export(struct obd_export *exp)
  {
  	if (exp) {
  		int connected;
  		spin_lock(&exp->exp_lock);
  		connected = exp->exp_conn_cnt > 0;
  		spin_unlock(&exp->exp_lock);
  		return connected;
  	}
  	return 0;
  }
  EXPORT_SYMBOL(class_connected_export);
  
  static void class_disconnect_export_list(struct list_head *list,
  					 enum obd_option flags)
  {
  	int rc;
  	struct obd_export *exp;
  
  	/* It's possible that an export may disconnect itself, but
  	 * nothing else will be added to this list. */
  	while (!list_empty(list)) {
  		exp = list_entry(list->next, struct obd_export,
  				     exp_obd_chain);
  		/* need for safe call CDEBUG after obd_disconnect */
  		class_export_get(exp);
  
  		spin_lock(&exp->exp_lock);
  		exp->exp_flags = flags;
  		spin_unlock(&exp->exp_lock);
  
  		if (obd_uuid_equals(&exp->exp_client_uuid,
  				    &exp->exp_obd->obd_uuid)) {
  			CDEBUG(D_HA,
  			       "exp %p export uuid == obd uuid, don't discon\n",
  			       exp);
  			/* Need to delete this now so we don't end up pointing
  			 * to work_list later when this export is cleaned up. */
  			list_del_init(&exp->exp_obd_chain);
  			class_export_put(exp);
  			continue;
  		}
  
  		class_export_get(exp);
  		CDEBUG(D_HA, "%s: disconnecting export at %s (%p), last request at " CFS_TIME_T "\n",
  		       exp->exp_obd->obd_name, obd_export_nid2str(exp),
  		       exp, exp->exp_last_request_time);
  		/* release one export reference anyway */
  		rc = obd_disconnect(exp);
  
  		CDEBUG(D_HA, "disconnected export at %s (%p): rc %d\n",
  		       obd_export_nid2str(exp), exp, rc);
  		class_export_put(exp);
  	}
  }
  
  void class_disconnect_exports(struct obd_device *obd)
  {
  	struct list_head work_list;
  
  	/* Move all of the exports from obd_exports to a work list, en masse. */
  	INIT_LIST_HEAD(&work_list);
  	spin_lock(&obd->obd_dev_lock);
  	list_splice_init(&obd->obd_exports, &work_list);
  	list_splice_init(&obd->obd_delayed_exports, &work_list);
  	spin_unlock(&obd->obd_dev_lock);
  
  	if (!list_empty(&work_list)) {
  		CDEBUG(D_HA, "OBD device %d (%p) has exports, disconnecting them\n",
  		       obd->obd_minor, obd);
  		class_disconnect_export_list(&work_list,
  					     exp_flags_from_obd(obd));
  	} else
  		CDEBUG(D_HA, "OBD device %d (%p) has no exports\n",
  		       obd->obd_minor, obd);
  }
  EXPORT_SYMBOL(class_disconnect_exports);
  
  /* Remove exports that have not completed recovery.
   */
  void class_disconnect_stale_exports(struct obd_device *obd,
  				    int (*test_export)(struct obd_export *))
  {
  	struct list_head work_list;
  	struct obd_export *exp, *n;
  	int evicted = 0;
  
  	INIT_LIST_HEAD(&work_list);
  	spin_lock(&obd->obd_dev_lock);
  	list_for_each_entry_safe(exp, n, &obd->obd_exports,
  				     exp_obd_chain) {
  		/* don't count self-export as client */
  		if (obd_uuid_equals(&exp->exp_client_uuid,
  				    &exp->exp_obd->obd_uuid))
  			continue;
  
  		/* don't evict clients which have no slot in last_rcvd
  		 * (e.g. lightweight connection) */
  		if (exp->exp_target_data.ted_lr_idx == -1)
  			continue;
  
  		spin_lock(&exp->exp_lock);
  		if (exp->exp_failed || test_export(exp)) {
  			spin_unlock(&exp->exp_lock);
  			continue;
  		}
  		exp->exp_failed = 1;
  		spin_unlock(&exp->exp_lock);
  
  		list_move(&exp->exp_obd_chain, &work_list);
  		evicted++;
  		CDEBUG(D_HA, "%s: disconnect stale client %s@%s\n",
  		       obd->obd_name, exp->exp_client_uuid.uuid,
  		       exp->exp_connection == NULL ? "<unknown>" :
  		       libcfs_nid2str(exp->exp_connection->c_peer.nid));
  		print_export_data(exp, "EVICTING", 0);
  	}
  	spin_unlock(&obd->obd_dev_lock);
  
  	if (evicted)
  		LCONSOLE_WARN("%s: disconnecting %d stale clients\n",
  			      obd->obd_name, evicted);
  
  	class_disconnect_export_list(&work_list, exp_flags_from_obd(obd) |
  						 OBD_OPT_ABORT_RECOV);
  }
  EXPORT_SYMBOL(class_disconnect_stale_exports);
  
  void class_fail_export(struct obd_export *exp)
  {
  	int rc, already_failed;
  
  	spin_lock(&exp->exp_lock);
  	already_failed = exp->exp_failed;
  	exp->exp_failed = 1;
  	spin_unlock(&exp->exp_lock);
  
  	if (already_failed) {
  		CDEBUG(D_HA, "disconnecting dead export %p/%s; skipping\n",
  		       exp, exp->exp_client_uuid.uuid);
  		return;
  	}
  
  	CDEBUG(D_HA, "disconnecting export %p/%s\n",
  	       exp, exp->exp_client_uuid.uuid);
  
  	if (obd_dump_on_timeout)
  		libcfs_debug_dumplog();
  
  	/* need for safe call CDEBUG after obd_disconnect */
  	class_export_get(exp);
  
  	/* Most callers into obd_disconnect are removing their own reference
  	 * (request, for example) in addition to the one from the hash table.
  	 * We don't have such a reference here, so make one. */
  	class_export_get(exp);
  	rc = obd_disconnect(exp);
  	if (rc)
  		CERROR("disconnecting export %p failed: %d\n", exp, rc);
  	else
  		CDEBUG(D_HA, "disconnected export %p/%s\n",
  		       exp, exp->exp_client_uuid.uuid);
  	class_export_put(exp);
  }
  EXPORT_SYMBOL(class_fail_export);
  
  char *obd_export_nid2str(struct obd_export *exp)
  {
  	if (exp->exp_connection != NULL)
  		return libcfs_nid2str(exp->exp_connection->c_peer.nid);
  
  	return "(no nid)";
  }
  EXPORT_SYMBOL(obd_export_nid2str);
  
  int obd_export_evict_by_nid(struct obd_device *obd, const char *nid)
  {
  	struct cfs_hash *nid_hash;
  	struct obd_export *doomed_exp = NULL;
  	int exports_evicted = 0;
  
  	lnet_nid_t nid_key = libcfs_str2nid((char *)nid);
  
  	spin_lock(&obd->obd_dev_lock);
  	/* umount has run already, so evict thread should leave
  	 * its task to umount thread now */
  	if (obd->obd_stopping) {
  		spin_unlock(&obd->obd_dev_lock);
  		return exports_evicted;
  	}
  	nid_hash = obd->obd_nid_hash;
  	cfs_hash_getref(nid_hash);
  	spin_unlock(&obd->obd_dev_lock);
  
  	do {
  		doomed_exp = cfs_hash_lookup(nid_hash, &nid_key);
  		if (doomed_exp == NULL)
  			break;
  
  		LASSERTF(doomed_exp->exp_connection->c_peer.nid == nid_key,
  			 "nid %s found, wanted nid %s, requested nid %s\n",
  			 obd_export_nid2str(doomed_exp),
  			 libcfs_nid2str(nid_key), nid);
  		LASSERTF(doomed_exp != obd->obd_self_export,
  			 "self-export is hashed by NID?\n");
  		exports_evicted++;
  		LCONSOLE_WARN("%s: evicting %s (at %s) by administrative request\n",
  			      obd->obd_name,
  			      obd_uuid2str(&doomed_exp->exp_client_uuid),
  			      obd_export_nid2str(doomed_exp));
  		class_fail_export(doomed_exp);
  		class_export_put(doomed_exp);
  	} while (1);
  
  	cfs_hash_putref(nid_hash);
  
  	if (!exports_evicted)
  		CDEBUG(D_HA,
  		       "%s: can't disconnect NID '%s': no exports found\n",
  		       obd->obd_name, nid);
  	return exports_evicted;
  }
  EXPORT_SYMBOL(obd_export_evict_by_nid);
  
  int obd_export_evict_by_uuid(struct obd_device *obd, const char *uuid)
  {
  	struct cfs_hash *uuid_hash;
  	struct obd_export *doomed_exp = NULL;
  	struct obd_uuid doomed_uuid;
  	int exports_evicted = 0;
  
  	spin_lock(&obd->obd_dev_lock);
  	if (obd->obd_stopping) {
  		spin_unlock(&obd->obd_dev_lock);
  		return exports_evicted;
  	}
  	uuid_hash = obd->obd_uuid_hash;
  	cfs_hash_getref(uuid_hash);
  	spin_unlock(&obd->obd_dev_lock);
  
  	obd_str2uuid(&doomed_uuid, uuid);
  	if (obd_uuid_equals(&doomed_uuid, &obd->obd_uuid)) {
  		CERROR("%s: can't evict myself\n", obd->obd_name);
  		cfs_hash_putref(uuid_hash);
  		return exports_evicted;
  	}
  
  	doomed_exp = cfs_hash_lookup(uuid_hash, &doomed_uuid);
  
  	if (doomed_exp == NULL) {
  		CERROR("%s: can't disconnect %s: no exports found\n",
  		       obd->obd_name, uuid);
  	} else {
  		CWARN("%s: evicting %s at administrative request\n",
  		       obd->obd_name, doomed_exp->exp_client_uuid.uuid);
  		class_fail_export(doomed_exp);
  		class_export_put(doomed_exp);
  		exports_evicted++;
  	}
  	cfs_hash_putref(uuid_hash);
  
  	return exports_evicted;
  }
  EXPORT_SYMBOL(obd_export_evict_by_uuid);
  
  #if LUSTRE_TRACKS_LOCK_EXP_REFS
  void (*class_export_dump_hook)(struct obd_export*) = NULL;
  EXPORT_SYMBOL(class_export_dump_hook);
  #endif
  
  static void print_export_data(struct obd_export *exp, const char *status,
  			      int locks)
  {
  	struct ptlrpc_reply_state *rs;
  	struct ptlrpc_reply_state *first_reply = NULL;
  	int nreplies = 0;
  
  	spin_lock(&exp->exp_lock);
  	list_for_each_entry(rs, &exp->exp_outstanding_replies,
  				rs_exp_list) {
  		if (nreplies == 0)
  			first_reply = rs;
  		nreplies++;
  	}
  	spin_unlock(&exp->exp_lock);
  
  	CDEBUG(D_HA, "%s: %s %p %s %s %d (%d %d %d) %d %d %d %d: %p %s %llu\n",
  	       exp->exp_obd->obd_name, status, exp, exp->exp_client_uuid.uuid,
  	       obd_export_nid2str(exp), atomic_read(&exp->exp_refcount),
  	       atomic_read(&exp->exp_rpc_count),
  	       atomic_read(&exp->exp_cb_count),
  	       atomic_read(&exp->exp_locks_count),
  	       exp->exp_disconnected, exp->exp_delayed, exp->exp_failed,
  	       nreplies, first_reply, nreplies > 3 ? "..." : "",
  	       exp->exp_last_committed);
  #if LUSTRE_TRACKS_LOCK_EXP_REFS
  	if (locks && class_export_dump_hook != NULL)
  		class_export_dump_hook(exp);
  #endif
  }
  
  void dump_exports(struct obd_device *obd, int locks)
  {
  	struct obd_export *exp;
  
  	spin_lock(&obd->obd_dev_lock);
  	list_for_each_entry(exp, &obd->obd_exports, exp_obd_chain)
  		print_export_data(exp, "ACTIVE", locks);
  	list_for_each_entry(exp, &obd->obd_unlinked_exports, exp_obd_chain)
  		print_export_data(exp, "UNLINKED", locks);
  	list_for_each_entry(exp, &obd->obd_delayed_exports, exp_obd_chain)
  		print_export_data(exp, "DELAYED", locks);
  	spin_unlock(&obd->obd_dev_lock);
  	spin_lock(&obd_zombie_impexp_lock);
  	list_for_each_entry(exp, &obd_zombie_exports, exp_obd_chain)
  		print_export_data(exp, "ZOMBIE", locks);
  	spin_unlock(&obd_zombie_impexp_lock);
  }
  EXPORT_SYMBOL(dump_exports);
  
  void obd_exports_barrier(struct obd_device *obd)
  {
  	int waited = 2;
  	LASSERT(list_empty(&obd->obd_exports));
  	spin_lock(&obd->obd_dev_lock);
  	while (!list_empty(&obd->obd_unlinked_exports)) {
  		spin_unlock(&obd->obd_dev_lock);
  		set_current_state(TASK_UNINTERRUPTIBLE);
  		schedule_timeout(cfs_time_seconds(waited));
  		if (waited > 5 && IS_PO2(waited)) {
  			LCONSOLE_WARN("%s is waiting for obd_unlinked_exports more than %d seconds. The obd refcount = %d. Is it stuck?\n",
  				      obd->obd_name, waited,
  				      atomic_read(&obd->obd_refcount));
  			dump_exports(obd, 1);
  		}
  		waited *= 2;
  		spin_lock(&obd->obd_dev_lock);
  	}
  	spin_unlock(&obd->obd_dev_lock);
  }
  EXPORT_SYMBOL(obd_exports_barrier);
  
  /* Total amount of zombies to be destroyed */
  static int zombies_count;
  
  /**
   * kill zombie imports and exports
   */
  void obd_zombie_impexp_cull(void)
  {
  	struct obd_import *import;
  	struct obd_export *export;
  
  	do {
  		spin_lock(&obd_zombie_impexp_lock);
  
  		import = NULL;
  		if (!list_empty(&obd_zombie_imports)) {
  			import = list_entry(obd_zombie_imports.next,
  						struct obd_import,
  						imp_zombie_chain);
  			list_del_init(&import->imp_zombie_chain);
  		}
  
  		export = NULL;
  		if (!list_empty(&obd_zombie_exports)) {
  			export = list_entry(obd_zombie_exports.next,
  						struct obd_export,
  						exp_obd_chain);
  			list_del_init(&export->exp_obd_chain);
  		}
  
  		spin_unlock(&obd_zombie_impexp_lock);
  
  		if (import != NULL) {
  			class_import_destroy(import);
  			spin_lock(&obd_zombie_impexp_lock);
  			zombies_count--;
  			spin_unlock(&obd_zombie_impexp_lock);
  		}
  
  		if (export != NULL) {
  			class_export_destroy(export);
  			spin_lock(&obd_zombie_impexp_lock);
  			zombies_count--;
  			spin_unlock(&obd_zombie_impexp_lock);
  		}
  
  		cond_resched();
  	} while (import != NULL || export != NULL);
  }
  
  static struct completion	obd_zombie_start;
  static struct completion	obd_zombie_stop;
  static unsigned long		obd_zombie_flags;
  static wait_queue_head_t		obd_zombie_waitq;
  static pid_t			obd_zombie_pid;
  
  enum {
  	OBD_ZOMBIE_STOP		= 0x0001,
  };
  
  /**
   * check for work for kill zombie import/export thread.
   */
  static int obd_zombie_impexp_check(void *arg)
  {
  	int rc;
  
  	spin_lock(&obd_zombie_impexp_lock);
  	rc = (zombies_count == 0) &&
  	     !test_bit(OBD_ZOMBIE_STOP, &obd_zombie_flags);
  	spin_unlock(&obd_zombie_impexp_lock);
  
  	return rc;
  }
  
  /**
   * Add export to the obd_zombie thread and notify it.
   */
  static void obd_zombie_export_add(struct obd_export *exp) {
  	spin_lock(&exp->exp_obd->obd_dev_lock);
  	LASSERT(!list_empty(&exp->exp_obd_chain));
  	list_del_init(&exp->exp_obd_chain);
  	spin_unlock(&exp->exp_obd->obd_dev_lock);
  	spin_lock(&obd_zombie_impexp_lock);
  	zombies_count++;
  	list_add(&exp->exp_obd_chain, &obd_zombie_exports);
  	spin_unlock(&obd_zombie_impexp_lock);
  
  	obd_zombie_impexp_notify();
  }
  
  /**
   * Add import to the obd_zombie thread and notify it.
   */
  static void obd_zombie_import_add(struct obd_import *imp) {
  	LASSERT(imp->imp_sec == NULL);
  	LASSERT(imp->imp_rq_pool == NULL);
  	spin_lock(&obd_zombie_impexp_lock);
  	LASSERT(list_empty(&imp->imp_zombie_chain));
  	zombies_count++;
  	list_add(&imp->imp_zombie_chain, &obd_zombie_imports);
  	spin_unlock(&obd_zombie_impexp_lock);
  
  	obd_zombie_impexp_notify();
  }
  
  /**
   * notify import/export destroy thread about new zombie.
   */
  static void obd_zombie_impexp_notify(void)
  {
  	/*
  	 * Make sure obd_zombie_impexp_thread get this notification.
  	 * It is possible this signal only get by obd_zombie_barrier, and
  	 * barrier gulps this notification and sleeps away and hangs ensues
  	 */
  	wake_up_all(&obd_zombie_waitq);
  }
  
  /**
   * check whether obd_zombie is idle
   */
  static int obd_zombie_is_idle(void)
  {
  	int rc;
  
  	LASSERT(!test_bit(OBD_ZOMBIE_STOP, &obd_zombie_flags));
  	spin_lock(&obd_zombie_impexp_lock);
  	rc = (zombies_count == 0);
  	spin_unlock(&obd_zombie_impexp_lock);
  	return rc;
  }
  
  /**
   * wait when obd_zombie import/export queues become empty
   */
  void obd_zombie_barrier(void)
  {
  	struct l_wait_info lwi = { 0 };
  
  	if (obd_zombie_pid == current_pid())
  		/* don't wait for myself */
  		return;
  	l_wait_event(obd_zombie_waitq, obd_zombie_is_idle(), &lwi);
  }
  EXPORT_SYMBOL(obd_zombie_barrier);
  
  
  /**
   * destroy zombie export/import thread.
   */
  static int obd_zombie_impexp_thread(void *unused)
  {
  	unshare_fs_struct();
  	complete(&obd_zombie_start);
  
  	obd_zombie_pid = current_pid();
  
  	while (!test_bit(OBD_ZOMBIE_STOP, &obd_zombie_flags)) {
  		struct l_wait_info lwi = { 0 };
  
  		l_wait_event(obd_zombie_waitq,
  			     !obd_zombie_impexp_check(NULL), &lwi);
  		obd_zombie_impexp_cull();
  
  		/*
  		 * Notify obd_zombie_barrier callers that queues
  		 * may be empty.
  		 */
  		wake_up(&obd_zombie_waitq);
  	}
  
  	complete(&obd_zombie_stop);
  
  	return 0;
  }
  
  
  /**
   * start destroy zombie import/export thread
   */
  int obd_zombie_impexp_init(void)
  {
  	struct task_struct *task;
  
  	INIT_LIST_HEAD(&obd_zombie_imports);
  	INIT_LIST_HEAD(&obd_zombie_exports);
  	spin_lock_init(&obd_zombie_impexp_lock);
  	init_completion(&obd_zombie_start);
  	init_completion(&obd_zombie_stop);
  	init_waitqueue_head(&obd_zombie_waitq);
  	obd_zombie_pid = 0;
  
  	task = kthread_run(obd_zombie_impexp_thread, NULL, "obd_zombid");
  	if (IS_ERR(task))
  		return PTR_ERR(task);
  
  	wait_for_completion(&obd_zombie_start);
  	return 0;
  }
  /**
   * stop destroy zombie import/export thread
   */
  void obd_zombie_impexp_stop(void)
  {
  	set_bit(OBD_ZOMBIE_STOP, &obd_zombie_flags);
  	obd_zombie_impexp_notify();
  	wait_for_completion(&obd_zombie_stop);
  }
  
  /***** Kernel-userspace comm helpers *******/
  
  /* Get length of entire message, including header */
  int kuc_len(int payload_len)
  {
  	return sizeof(struct kuc_hdr) + payload_len;
  }
  EXPORT_SYMBOL(kuc_len);
  
  /* Get a pointer to kuc header, given a ptr to the payload
   * @param p Pointer to payload area
   * @returns Pointer to kuc header
   */
  struct kuc_hdr *kuc_ptr(void *p)
  {
  	struct kuc_hdr *lh = ((struct kuc_hdr *)p) - 1;
  	LASSERT(lh->kuc_magic == KUC_MAGIC);
  	return lh;
  }
  EXPORT_SYMBOL(kuc_ptr);
  
  /* Test if payload is part of kuc message
   * @param p Pointer to payload area
   * @returns boolean
   */
  int kuc_ispayload(void *p)
  {
  	struct kuc_hdr *kh = ((struct kuc_hdr *)p) - 1;
  
  	if (kh->kuc_magic == KUC_MAGIC)
  		return 1;
  	else
  		return 0;
  }
  EXPORT_SYMBOL(kuc_ispayload);
  
  /* Alloc space for a message, and fill in header
   * @return Pointer to payload area
   */
  void *kuc_alloc(int payload_len, int transport, int type)
  {
  	struct kuc_hdr *lh;
  	int len = kuc_len(payload_len);
  
  	OBD_ALLOC(lh, len);
  	if (lh == NULL)
  		return ERR_PTR(-ENOMEM);
  
  	lh->kuc_magic = KUC_MAGIC;
  	lh->kuc_transport = transport;
  	lh->kuc_msgtype = type;
  	lh->kuc_msglen = len;
  
  	return (void *)(lh + 1);
  }
  EXPORT_SYMBOL(kuc_alloc);
  
  /* Takes pointer to payload area */
  inline void kuc_free(void *p, int payload_len)
  {
  	struct kuc_hdr *lh = kuc_ptr(p);
  	OBD_FREE(lh, kuc_len(payload_len));
  }
  EXPORT_SYMBOL(kuc_free);
  