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) 2008, 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.
   *
   * Client Lustre Object.
   *
   *   Author: Nikita Danilov <nikita.danilov@sun.com>
   *   Author: Jinshan Xiong <jinshan.xiong@intel.com>
   */
  
  /*
   * Locking.
   *
   *  i_mutex
   *      PG_locked
   *	  ->coh_attr_guard
   *	  ->ls_guard
   */
  
  #define DEBUG_SUBSYSTEM S_CLASS
  
  #include <linux/libcfs/libcfs.h>
  /* class_put_type() */
  #include <obd_class.h>
  #include <obd_support.h>
  #include <lustre_fid.h>
  #include <linux/list.h>
  #include <linux/libcfs/libcfs_hash.h>	/* for cfs_hash stuff */
  #include <cl_object.h>
  #include <lu_object.h>
  #include "cl_internal.h"
  
  static struct kmem_cache *cl_env_kmem;
  
  /** Lock class of cl_object_header::coh_attr_guard */
  static struct lock_class_key cl_attr_guard_class;
  
  /**
   * Initialize cl_object_header.
   */
  int cl_object_header_init(struct cl_object_header *h)
  {
  	int result;
  
  	result = lu_object_header_init(&h->coh_lu);
  	if (result == 0) {
  		spin_lock_init(&h->coh_attr_guard);
  		lockdep_set_class(&h->coh_attr_guard, &cl_attr_guard_class);
  		h->coh_page_bufsize = 0;
  	}
  	return result;
  }
  EXPORT_SYMBOL(cl_object_header_init);
  
  /**
   * Returns a cl_object with a given \a fid.
   *
   * Returns either cached or newly created object. Additional reference on the
   * returned object is acquired.
   *
   * \see lu_object_find(), cl_page_find(), cl_lock_find()
   */
  struct cl_object *cl_object_find(const struct lu_env *env,
  				 struct cl_device *cd, const struct lu_fid *fid,
  				 const struct cl_object_conf *c)
  {
  	might_sleep();
  	return lu2cl(lu_object_find_slice(env, cl2lu_dev(cd), fid, &c->coc_lu));
  }
  EXPORT_SYMBOL(cl_object_find);
  
  /**
   * Releases a reference on \a o.
   *
   * When last reference is released object is returned to the cache, unless
   * lu_object_header_flags::LU_OBJECT_HEARD_BANSHEE bit is set in its header.
   *
   * \see cl_page_put(), cl_lock_put().
   */
  void cl_object_put(const struct lu_env *env, struct cl_object *o)
  {
  	lu_object_put(env, &o->co_lu);
  }
  EXPORT_SYMBOL(cl_object_put);
  
  /**
   * Acquire an additional reference to the object \a o.
   *
   * This can only be used to acquire _additional_ reference, i.e., caller
   * already has to possess at least one reference to \a o before calling this.
   *
   * \see cl_page_get(), cl_lock_get().
   */
  void cl_object_get(struct cl_object *o)
  {
  	lu_object_get(&o->co_lu);
  }
  EXPORT_SYMBOL(cl_object_get);
  
  /**
   * Returns the top-object for a given \a o.
   *
   * \see cl_io_top()
   */
  struct cl_object *cl_object_top(struct cl_object *o)
  {
  	struct cl_object_header *hdr = cl_object_header(o);
  	struct cl_object *top;
  
  	while (hdr->coh_parent)
  		hdr = hdr->coh_parent;
  
  	top = lu2cl(lu_object_top(&hdr->coh_lu));
  	CDEBUG(D_TRACE, "%p -> %p\n", o, top);
  	return top;
  }
  EXPORT_SYMBOL(cl_object_top);
  
  /**
   * Returns pointer to the lock protecting data-attributes for the given object
   * \a o.
   *
   * Data-attributes are protected by the cl_object_header::coh_attr_guard
   * spin-lock in the top-object.
   *
   * \see cl_attr, cl_object_attr_lock(), cl_object_operations::coo_attr_get().
   */
  static spinlock_t *cl_object_attr_guard(struct cl_object *o)
  {
  	return &cl_object_header(cl_object_top(o))->coh_attr_guard;
  }
  
  /**
   * Locks data-attributes.
   *
   * Prevents data-attributes from changing, until lock is released by
   * cl_object_attr_unlock(). This has to be called before calls to
   * cl_object_attr_get(), cl_object_attr_update().
   */
  void cl_object_attr_lock(struct cl_object *o)
  	__acquires(cl_object_attr_guard(o))
  {
  	spin_lock(cl_object_attr_guard(o));
  }
  EXPORT_SYMBOL(cl_object_attr_lock);
  
  /**
   * Releases data-attributes lock, acquired by cl_object_attr_lock().
   */
  void cl_object_attr_unlock(struct cl_object *o)
  	__releases(cl_object_attr_guard(o))
  {
  	spin_unlock(cl_object_attr_guard(o));
  }
  EXPORT_SYMBOL(cl_object_attr_unlock);
  
  /**
   * Returns data-attributes of an object \a obj.
   *
   * Every layer is asked (by calling cl_object_operations::coo_attr_get())
   * top-to-bottom to fill in parts of \a attr that this layer is responsible
   * for.
   */
  int cl_object_attr_get(const struct lu_env *env, struct cl_object *obj,
  		       struct cl_attr *attr)
  {
  	struct lu_object_header *top;
  	int result;
  
  	assert_spin_locked(cl_object_attr_guard(obj));
  
  	top = obj->co_lu.lo_header;
  	result = 0;
  	list_for_each_entry(obj, &top->loh_layers, co_lu.lo_linkage) {
  		if (obj->co_ops->coo_attr_get) {
  			result = obj->co_ops->coo_attr_get(env, obj, attr);
  			if (result != 0) {
  				if (result > 0)
  					result = 0;
  				break;
  			}
  		}
  	}
  	return result;
  }
  EXPORT_SYMBOL(cl_object_attr_get);
  
  /**
   * Updates data-attributes of an object \a obj.
   *
   * Only attributes, mentioned in a validness bit-mask \a v are
   * updated. Calls cl_object_operations::coo_attr_update() on every layer,
   * bottom to top.
   */
  int cl_object_attr_update(const struct lu_env *env, struct cl_object *obj,
  			  const struct cl_attr *attr, unsigned int v)
  {
  	struct lu_object_header *top;
  	int result;
  
  	assert_spin_locked(cl_object_attr_guard(obj));
  
  	top = obj->co_lu.lo_header;
  	result = 0;
  	list_for_each_entry_reverse(obj, &top->loh_layers, co_lu.lo_linkage) {
  		if (obj->co_ops->coo_attr_update) {
  			result = obj->co_ops->coo_attr_update(env, obj, attr,
  							      v);
  			if (result != 0) {
  				if (result > 0)
  					result = 0;
  				break;
  			}
  		}
  	}
  	return result;
  }
  EXPORT_SYMBOL(cl_object_attr_update);
  
  /**
   * Notifies layers (bottom-to-top) that glimpse AST was received.
   *
   * Layers have to fill \a lvb fields with information that will be shipped
   * back to glimpse issuer.
   *
   * \see cl_lock_operations::clo_glimpse()
   */
  int cl_object_glimpse(const struct lu_env *env, struct cl_object *obj,
  		      struct ost_lvb *lvb)
  {
  	struct lu_object_header *top;
  	int result;
  
  	top = obj->co_lu.lo_header;
  	result = 0;
  	list_for_each_entry_reverse(obj, &top->loh_layers, co_lu.lo_linkage) {
  		if (obj->co_ops->coo_glimpse) {
  			result = obj->co_ops->coo_glimpse(env, obj, lvb);
  			if (result != 0)
  				break;
  		}
  	}
  	LU_OBJECT_HEADER(D_DLMTRACE, env, lu_object_top(top),
  			 "size: %llu mtime: %llu atime: %llu ctime: %llu blocks: %llu\n",
  			 lvb->lvb_size, lvb->lvb_mtime, lvb->lvb_atime,
  			 lvb->lvb_ctime, lvb->lvb_blocks);
  	return result;
  }
  EXPORT_SYMBOL(cl_object_glimpse);
  
  /**
   * Updates a configuration of an object \a obj.
   */
  int cl_conf_set(const struct lu_env *env, struct cl_object *obj,
  		const struct cl_object_conf *conf)
  {
  	struct lu_object_header *top;
  	int result;
  
  	top = obj->co_lu.lo_header;
  	result = 0;
  	list_for_each_entry(obj, &top->loh_layers, co_lu.lo_linkage) {
  		if (obj->co_ops->coo_conf_set) {
  			result = obj->co_ops->coo_conf_set(env, obj, conf);
  			if (result != 0)
  				break;
  		}
  	}
  	return result;
  }
  EXPORT_SYMBOL(cl_conf_set);
  
  /**
   * Prunes caches of pages and locks for this object.
   */
  int cl_object_prune(const struct lu_env *env, struct cl_object *obj)
  {
  	struct lu_object_header *top;
  	struct cl_object *o;
  	int result;
  
  	top = obj->co_lu.lo_header;
  	result = 0;
  	list_for_each_entry(o, &top->loh_layers, co_lu.lo_linkage) {
  		if (o->co_ops->coo_prune) {
  			result = o->co_ops->coo_prune(env, o);
  			if (result != 0)
  				break;
  		}
  	}
  
  	return result;
  }
  EXPORT_SYMBOL(cl_object_prune);
  
  /**
   * Get stripe information of this object.
   */
  int cl_object_getstripe(const struct lu_env *env, struct cl_object *obj,
  			struct lov_user_md __user *uarg)
  {
  	struct lu_object_header *top;
  	int result = 0;
  
  	top = obj->co_lu.lo_header;
  	list_for_each_entry(obj, &top->loh_layers, co_lu.lo_linkage) {
  		if (obj->co_ops->coo_getstripe) {
  			result = obj->co_ops->coo_getstripe(env, obj, uarg);
  			if (result)
  				break;
  		}
  	}
  	return result;
  }
  EXPORT_SYMBOL(cl_object_getstripe);
  
  /**
   * Get fiemap extents from file object.
   *
   * \param env [in]	lustre environment
   * \param obj [in]	file object
   * \param key [in]	fiemap request argument
   * \param fiemap [out]	fiemap extents mapping retrived
   * \param buflen [in]	max buffer length of @fiemap
   *
   * \retval 0	success
   * \retval < 0	error
   */
  int cl_object_fiemap(const struct lu_env *env, struct cl_object *obj,
  		     struct ll_fiemap_info_key *key,
  		     struct fiemap *fiemap, size_t *buflen)
  {
  	struct lu_object_header *top;
  	int result = 0;
  
  	top = obj->co_lu.lo_header;
  	list_for_each_entry(obj, &top->loh_layers, co_lu.lo_linkage) {
  		if (obj->co_ops->coo_fiemap) {
  			result = obj->co_ops->coo_fiemap(env, obj, key, fiemap,
  							 buflen);
  			if (result)
  				break;
  		}
  	}
  	return result;
  }
  EXPORT_SYMBOL(cl_object_fiemap);
  
  int cl_object_layout_get(const struct lu_env *env, struct cl_object *obj,
  			 struct cl_layout *cl)
  {
  	struct lu_object_header *top = obj->co_lu.lo_header;
  
  	list_for_each_entry(obj, &top->loh_layers, co_lu.lo_linkage) {
  		if (obj->co_ops->coo_layout_get)
  			return obj->co_ops->coo_layout_get(env, obj, cl);
  	}
  
  	return -EOPNOTSUPP;
  }
  EXPORT_SYMBOL(cl_object_layout_get);
  
  loff_t cl_object_maxbytes(struct cl_object *obj)
  {
  	struct lu_object_header *top = obj->co_lu.lo_header;
  	loff_t maxbytes = LLONG_MAX;
  
  	list_for_each_entry(obj, &top->loh_layers, co_lu.lo_linkage) {
  		if (obj->co_ops->coo_maxbytes)
  			maxbytes = min_t(loff_t, obj->co_ops->coo_maxbytes(obj),
  					 maxbytes);
  	}
  
  	return maxbytes;
  }
  EXPORT_SYMBOL(cl_object_maxbytes);
  
  /**
   * Helper function removing all object locks, and marking object for
   * deletion. All object pages must have been deleted at this point.
   *
   * This is called by cl_inode_fini() and lov_object_delete() to destroy top-
   * and sub- objects respectively.
   */
  void cl_object_kill(const struct lu_env *env, struct cl_object *obj)
  {
  	struct cl_object_header *hdr = cl_object_header(obj);
  
  	set_bit(LU_OBJECT_HEARD_BANSHEE, &hdr->coh_lu.loh_flags);
  }
  EXPORT_SYMBOL(cl_object_kill);
  
  void cache_stats_init(struct cache_stats *cs, const char *name)
  {
  	int i;
  
  	cs->cs_name = name;
  	for (i = 0; i < CS_NR; i++)
  		atomic_set(&cs->cs_stats[i], 0);
  }
  
  static int cache_stats_print(const struct cache_stats *cs,
  			     struct seq_file *m, int h)
  {
  	int i;
  	/*
  	 *   lookup    hit    total  cached create
  	 * env: ...... ...... ...... ...... ......
  	 */
  	if (h) {
  		const char *names[CS_NR] = CS_NAMES;
  
  		seq_printf(m, "%6s", " ");
  		for (i = 0; i < CS_NR; i++)
  			seq_printf(m, "%8s", names[i]);
  		seq_printf(m, "\n");
  	}
  
  	seq_printf(m, "%5.5s:", cs->cs_name);
  	for (i = 0; i < CS_NR; i++)
  		seq_printf(m, "%8u", atomic_read(&cs->cs_stats[i]));
  	return 0;
  }
  
  static void cl_env_percpu_refill(void);
  
  /**
   * Initialize client site.
   *
   * Perform common initialization (lu_site_init()), and initialize statistical
   * counters. Also perform global initializations on the first call.
   */
  int cl_site_init(struct cl_site *s, struct cl_device *d)
  {
  	size_t i;
  	int result;
  
  	result = lu_site_init(&s->cs_lu, &d->cd_lu_dev);
  	if (result == 0) {
  		cache_stats_init(&s->cs_pages, "pages");
  		for (i = 0; i < ARRAY_SIZE(s->cs_pages_state); ++i)
  			atomic_set(&s->cs_pages_state[0], 0);
  		cl_env_percpu_refill();
  	}
  	return result;
  }
  EXPORT_SYMBOL(cl_site_init);
  
  /**
   * Finalize client site. Dual to cl_site_init().
   */
  void cl_site_fini(struct cl_site *s)
  {
  	lu_site_fini(&s->cs_lu);
  }
  EXPORT_SYMBOL(cl_site_fini);
  
  static struct cache_stats cl_env_stats = {
  	.cs_name    = "envs",
  	.cs_stats = { ATOMIC_INIT(0), }
  };
  
  /**
   * Outputs client site statistical counters into a buffer. Suitable for
   * ll_rd_*()-style functions.
   */
  int cl_site_stats_print(const struct cl_site *site, struct seq_file *m)
  {
  	size_t i;
  	static const char * const pstate[] = {
  		[CPS_CACHED]  = "c",
  		[CPS_OWNED]   = "o",
  		[CPS_PAGEOUT] = "w",
  		[CPS_PAGEIN]  = "r",
  		[CPS_FREEING] = "f"
  	};
  /*
         lookup    hit  total   busy create
  pages: ...... ...... ...... ...... ...... [...... ...... ...... ......]
  locks: ...... ...... ...... ...... ...... [...... ...... ...... ...... ......]
    env: ...... ...... ...... ...... ......
   */
  	lu_site_stats_print(&site->cs_lu, m);
  	cache_stats_print(&site->cs_pages, m, 1);
  	seq_puts(m, " [");
  	for (i = 0; i < ARRAY_SIZE(site->cs_pages_state); ++i)
  		seq_printf(m, "%s: %u ", pstate[i],
  			   atomic_read(&site->cs_pages_state[i]));
  	seq_puts(m, "]\n");
  	cache_stats_print(&cl_env_stats, m, 0);
  	seq_puts(m, "\n");
  	return 0;
  }
  EXPORT_SYMBOL(cl_site_stats_print);
  
  /*****************************************************************************
   *
   * lu_env handling on client.
   *
   */
  
  /**
   * The most efficient way is to store cl_env pointer in task specific
   * structures. On Linux, it wont' be easy to use task_struct->journal_info
   * because Lustre code may call into other fs which has certain assumptions
   * about journal_info. Currently following fields in task_struct are identified
   * can be used for this purpose:
   *  - tux_info: only on RedHat kernel.
   *  - ...
   * \note As long as we use task_struct to store cl_env, we assume that once
   * called into Lustre, we'll never call into the other part of the kernel
   * which will use those fields in task_struct without explicitly exiting
   * Lustre.
   *
   * If there's no space in task_struct is available, hash will be used.
   * bz20044, bz22683.
   */
  
  static unsigned int cl_envs_cached_max = 32; /* XXX: prototype: arbitrary limit
  					      * for now.
  					      */
  static struct cl_env_cache {
  	rwlock_t		cec_guard;
  	unsigned int		cec_count;
  	struct list_head	cec_envs;
  } *cl_envs = NULL;
  
  struct cl_env {
  	void	     *ce_magic;
  	struct lu_env     ce_lu;
  	struct lu_context ce_ses;
  
  	/*
  	 * Linkage into global list of all client environments. Used for
  	 * garbage collection.
  	 */
  	struct list_head	ce_linkage;
  	/*
  	 *
  	 */
  	int	       ce_ref;
  	/*
  	 * Debugging field: address of the caller who made original
  	 * allocation.
  	 */
  	void	     *ce_debug;
  };
  
  #define CL_ENV_INC(counter)
  #define CL_ENV_DEC(counter)
  
  static void cl_env_init0(struct cl_env *cle, void *debug)
  {
  	LASSERT(cle->ce_ref == 0);
  	LASSERT(cle->ce_magic == &cl_env_init0);
  	LASSERT(!cle->ce_debug);
  
  	cle->ce_ref = 1;
  	cle->ce_debug = debug;
  	CL_ENV_INC(busy);
  }
  
  static struct lu_env *cl_env_new(__u32 ctx_tags, __u32 ses_tags, void *debug)
  {
  	struct lu_env *env;
  	struct cl_env *cle;
  
  	cle = kmem_cache_zalloc(cl_env_kmem, GFP_NOFS);
  	if (cle) {
  		int rc;
  
  		INIT_LIST_HEAD(&cle->ce_linkage);
  		cle->ce_magic = &cl_env_init0;
  		env = &cle->ce_lu;
  		rc = lu_env_init(env, ctx_tags | LCT_CL_THREAD);
  		if (rc == 0) {
  			rc = lu_context_init(&cle->ce_ses,
  					     ses_tags | LCT_SESSION);
  			if (rc == 0) {
  				lu_context_enter(&cle->ce_ses);
  				env->le_ses = &cle->ce_ses;
  				cl_env_init0(cle, debug);
  			} else {
  				lu_env_fini(env);
  			}
  		}
  		if (rc != 0) {
  			kmem_cache_free(cl_env_kmem, cle);
  			env = ERR_PTR(rc);
  		} else {
  			CL_ENV_INC(create);
  			CL_ENV_INC(total);
  		}
  	} else {
  		env = ERR_PTR(-ENOMEM);
  	}
  	return env;
  }
  
  static void cl_env_fini(struct cl_env *cle)
  {
  	CL_ENV_DEC(total);
  	lu_context_fini(&cle->ce_lu.le_ctx);
  	lu_context_fini(&cle->ce_ses);
  	kmem_cache_free(cl_env_kmem, cle);
  }
  
  static struct lu_env *cl_env_obtain(void *debug)
  {
  	struct cl_env *cle;
  	struct lu_env *env;
  	int cpu = get_cpu();
  
  	read_lock(&cl_envs[cpu].cec_guard);
  	LASSERT(equi(cl_envs[cpu].cec_count == 0,
  		     list_empty(&cl_envs[cpu].cec_envs)));
  	if (cl_envs[cpu].cec_count > 0) {
  		int rc;
  
  		cle = container_of(cl_envs[cpu].cec_envs.next, struct cl_env,
  				   ce_linkage);
  		list_del_init(&cle->ce_linkage);
  		cl_envs[cpu].cec_count--;
  		read_unlock(&cl_envs[cpu].cec_guard);
  		put_cpu();
  
  		env = &cle->ce_lu;
  		rc = lu_env_refill(env);
  		if (rc == 0) {
  			cl_env_init0(cle, debug);
  			lu_context_enter(&env->le_ctx);
  			lu_context_enter(&cle->ce_ses);
  		} else {
  			cl_env_fini(cle);
  			env = ERR_PTR(rc);
  		}
  	} else {
  		read_unlock(&cl_envs[cpu].cec_guard);
  		put_cpu();
  		env = cl_env_new(lu_context_tags_default,
  				 lu_session_tags_default, debug);
  	}
  	return env;
  }
  
  static inline struct cl_env *cl_env_container(struct lu_env *env)
  {
  	return container_of(env, struct cl_env, ce_lu);
  }
  
  /**
   * Returns lu_env: if there already is an environment associated with the
   * current thread, it is returned, otherwise, new environment is allocated.
   *
   * Allocations are amortized through the global cache of environments.
   *
   * \param refcheck pointer to a counter used to detect environment leaks. In
   * the usual case cl_env_get() and cl_env_put() are called in the same lexical
   * scope and pointer to the same integer is passed as \a refcheck. This is
   * used to detect missed cl_env_put().
   *
   * \see cl_env_put()
   */
  struct lu_env *cl_env_get(u16 *refcheck)
  {
  	struct lu_env *env;
  
  	env = cl_env_obtain(__builtin_return_address(0));
  	if (!IS_ERR(env)) {
  		struct cl_env *cle;
  
  		cle = cl_env_container(env);
  		*refcheck = cle->ce_ref;
  		CDEBUG(D_OTHER, "%d@%p\n", cle->ce_ref, cle);
  	}
  	return env;
  }
  EXPORT_SYMBOL(cl_env_get);
  
  /**
   * Forces an allocation of a fresh environment with given tags.
   *
   * \see cl_env_get()
   */
  struct lu_env *cl_env_alloc(u16 *refcheck, u32 tags)
  {
  	struct lu_env *env;
  
  	env = cl_env_new(tags, tags, __builtin_return_address(0));
  	if (!IS_ERR(env)) {
  		struct cl_env *cle;
  
  		cle = cl_env_container(env);
  		*refcheck = cle->ce_ref;
  		CDEBUG(D_OTHER, "%d@%p\n", cle->ce_ref, cle);
  	}
  	return env;
  }
  EXPORT_SYMBOL(cl_env_alloc);
  
  static void cl_env_exit(struct cl_env *cle)
  {
  	lu_context_exit(&cle->ce_lu.le_ctx);
  	lu_context_exit(&cle->ce_ses);
  }
  
  /**
   * Finalizes and frees a given number of cached environments. This is done to
   * (1) free some memory (not currently hooked into VM), or (2) release
   * references to modules.
   */
  unsigned int cl_env_cache_purge(unsigned int nr)
  {
  	struct cl_env *cle;
  	unsigned int i;
  
  	for_each_possible_cpu(i) {
  		write_lock(&cl_envs[i].cec_guard);
  		for (; !list_empty(&cl_envs[i].cec_envs) && nr > 0; --nr) {
  			cle = container_of(cl_envs[i].cec_envs.next,
  					   struct cl_env, ce_linkage);
  			list_del_init(&cle->ce_linkage);
  			LASSERT(cl_envs[i].cec_count > 0);
  			cl_envs[i].cec_count--;
  			write_unlock(&cl_envs[i].cec_guard);
  
  			cl_env_fini(cle);
  			write_lock(&cl_envs[i].cec_guard);
  		}
  		LASSERT(equi(cl_envs[i].cec_count == 0,
  			     list_empty(&cl_envs[i].cec_envs)));
  		write_unlock(&cl_envs[i].cec_guard);
  	}
  	return nr;
  }
  EXPORT_SYMBOL(cl_env_cache_purge);
  
  /**
   * Release an environment.
   *
   * Decrement \a env reference counter. When counter drops to 0, nothing in
   * this thread is using environment and it is returned to the allocation
   * cache, or freed straight away, if cache is large enough.
   */
  void cl_env_put(struct lu_env *env, u16 *refcheck)
  {
  	struct cl_env *cle;
  
  	cle = cl_env_container(env);
  
  	LASSERT(cle->ce_ref > 0);
  	LASSERT(ergo(refcheck, cle->ce_ref == *refcheck));
  
  	CDEBUG(D_OTHER, "%d@%p\n", cle->ce_ref, cle);
  	if (--cle->ce_ref == 0) {
  		int cpu = get_cpu();
  
  		CL_ENV_DEC(busy);
  		cle->ce_debug = NULL;
  		cl_env_exit(cle);
  		/*
  		 * Don't bother to take a lock here.
  		 *
  		 * Return environment to the cache only when it was allocated
  		 * with the standard tags.
  		 */
  		if (cl_envs[cpu].cec_count < cl_envs_cached_max &&
  		    (env->le_ctx.lc_tags & ~LCT_HAS_EXIT) == LCT_CL_THREAD &&
  		    (env->le_ses->lc_tags & ~LCT_HAS_EXIT) == LCT_SESSION) {
  			read_lock(&cl_envs[cpu].cec_guard);
  			list_add(&cle->ce_linkage, &cl_envs[cpu].cec_envs);
  			cl_envs[cpu].cec_count++;
  			read_unlock(&cl_envs[cpu].cec_guard);
  		} else {
  			cl_env_fini(cle);
  		}
  		put_cpu();
  	}
  }
  EXPORT_SYMBOL(cl_env_put);
  
  /**
   * Converts struct ost_lvb to struct cl_attr.
   *
   * \see cl_attr2lvb
   */
  void cl_lvb2attr(struct cl_attr *attr, const struct ost_lvb *lvb)
  {
  	attr->cat_size   = lvb->lvb_size;
  	attr->cat_mtime  = lvb->lvb_mtime;
  	attr->cat_atime  = lvb->lvb_atime;
  	attr->cat_ctime  = lvb->lvb_ctime;
  	attr->cat_blocks = lvb->lvb_blocks;
  }
  EXPORT_SYMBOL(cl_lvb2attr);
  
  static struct cl_env cl_env_percpu[NR_CPUS];
  
  static int cl_env_percpu_init(void)
  {
  	struct cl_env *cle;
  	int tags = LCT_REMEMBER | LCT_NOREF;
  	int i, j;
  	int rc = 0;
  
  	for_each_possible_cpu(i) {
  		struct lu_env *env;
  
  		rwlock_init(&cl_envs[i].cec_guard);
  		INIT_LIST_HEAD(&cl_envs[i].cec_envs);
  		cl_envs[i].cec_count = 0;
  
  		cle = &cl_env_percpu[i];
  		env = &cle->ce_lu;
  
  		INIT_LIST_HEAD(&cle->ce_linkage);
  		cle->ce_magic = &cl_env_init0;
  		rc = lu_env_init(env, LCT_CL_THREAD | tags);
  		if (rc == 0) {
  			rc = lu_context_init(&cle->ce_ses, LCT_SESSION | tags);
  			if (rc == 0) {
  				lu_context_enter(&cle->ce_ses);
  				env->le_ses = &cle->ce_ses;
  			} else {
  				lu_env_fini(env);
  			}
  		}
  		if (rc != 0)
  			break;
  	}
  	if (rc != 0) {
  		/* Indices 0 to i (excluding i) were correctly initialized,
  		 * thus we must uninitialize up to i, the rest are undefined.
  		 */
  		for (j = 0; j < i; j++) {
  			cle = &cl_env_percpu[j];
  			lu_context_exit(&cle->ce_ses);
  			lu_context_fini(&cle->ce_ses);
  			lu_env_fini(&cle->ce_lu);
  		}
  	}
  
  	return rc;
  }
  
  static void cl_env_percpu_fini(void)
  {
  	int i;
  
  	for_each_possible_cpu(i) {
  		struct cl_env *cle = &cl_env_percpu[i];
  
  		lu_context_exit(&cle->ce_ses);
  		lu_context_fini(&cle->ce_ses);
  		lu_env_fini(&cle->ce_lu);
  	}
  }
  
  static void cl_env_percpu_refill(void)
  {
  	int i;
  
  	for_each_possible_cpu(i)
  		lu_env_refill(&cl_env_percpu[i].ce_lu);
  }
  
  void cl_env_percpu_put(struct lu_env *env)
  {
  	struct cl_env *cle;
  	int cpu;
  
  	cpu = smp_processor_id();
  	cle = cl_env_container(env);
  	LASSERT(cle == &cl_env_percpu[cpu]);
  
  	cle->ce_ref--;
  	LASSERT(cle->ce_ref == 0);
  
  	CL_ENV_DEC(busy);
  	cle->ce_debug = NULL;
  
  	put_cpu();
  }
  EXPORT_SYMBOL(cl_env_percpu_put);
  
  struct lu_env *cl_env_percpu_get(void)
  {
  	struct cl_env *cle;
  
  	cle = &cl_env_percpu[get_cpu()];
  	cl_env_init0(cle, __builtin_return_address(0));
  
  	return &cle->ce_lu;
  }
  EXPORT_SYMBOL(cl_env_percpu_get);
  
  /*****************************************************************************
   *
   * Temporary prototype thing: mirror obd-devices into cl devices.
   *
   */
  
  struct cl_device *cl_type_setup(const struct lu_env *env, struct lu_site *site,
  				struct lu_device_type *ldt,
  				struct lu_device *next)
  {
  	const char       *typename;
  	struct lu_device *d;
  
  	typename = ldt->ldt_name;
  	d = ldt->ldt_ops->ldto_device_alloc(env, ldt, NULL);
  	if (!IS_ERR(d)) {
  		int rc;
  
  		if (site)
  			d->ld_site = site;
  		rc = ldt->ldt_ops->ldto_device_init(env, d, typename, next);
  		if (rc == 0) {
  			lu_device_get(d);
  			lu_ref_add(&d->ld_reference,
  				   "lu-stack", &lu_site_init);
  		} else {
  			ldt->ldt_ops->ldto_device_free(env, d);
  			CERROR("can't init device '%s', %d\n", typename, rc);
  			d = ERR_PTR(rc);
  		}
  	} else {
  		CERROR("Cannot allocate device: '%s'\n", typename);
  	}
  	return lu2cl_dev(d);
  }
  EXPORT_SYMBOL(cl_type_setup);
  
  /**
   * Finalize device stack by calling lu_stack_fini().
   */
  void cl_stack_fini(const struct lu_env *env, struct cl_device *cl)
  {
  	lu_stack_fini(env, cl2lu_dev(cl));
  }
  EXPORT_SYMBOL(cl_stack_fini);
  
  static struct lu_context_key cl_key;
  
  struct cl_thread_info *cl_env_info(const struct lu_env *env)
  {
  	return lu_context_key_get(&env->le_ctx, &cl_key);
  }
  
  /* defines cl0_key_{init,fini}() */
  LU_KEY_INIT_FINI(cl0, struct cl_thread_info);
  
  static void *cl_key_init(const struct lu_context *ctx,
  			 struct lu_context_key *key)
  {
  	return cl0_key_init(ctx, key);
  }
  
  static void cl_key_fini(const struct lu_context *ctx,
  			struct lu_context_key *key, void *data)
  {
  	cl0_key_fini(ctx, key, data);
  }
  
  static struct lu_context_key cl_key = {
  	.lct_tags = LCT_CL_THREAD,
  	.lct_init = cl_key_init,
  	.lct_fini = cl_key_fini,
  };
  
  static struct lu_kmem_descr cl_object_caches[] = {
  	{
  		.ckd_cache = &cl_env_kmem,
  		.ckd_name  = "cl_env_kmem",
  		.ckd_size  = sizeof(struct cl_env)
  	},
  	{
  		.ckd_cache = NULL
  	}
  };
  
  /**
   * Global initialization of cl-data. Create kmem caches, register
   * lu_context_key's, etc.
   *
   * \see cl_global_fini()
   */
  int cl_global_init(void)
  {
  	int result;
  
  	cl_envs = kcalloc(num_possible_cpus(), sizeof(*cl_envs), GFP_KERNEL);
  	if (!cl_envs) {
  		result = -ENOMEM;
  		goto out;
  	}
  
  	result = lu_kmem_init(cl_object_caches);
  	if (result)
  		goto out_envs;
  
  	LU_CONTEXT_KEY_INIT(&cl_key);
  	result = lu_context_key_register(&cl_key);
  	if (result)
  		goto out_kmem;
  
  	result = cl_env_percpu_init();
  	if (result)
  		/* no cl_env_percpu_fini on error */
  		goto out_keys;
  
  	return 0;
  
  out_keys:
  	lu_context_key_degister(&cl_key);
  out_kmem:
  	lu_kmem_fini(cl_object_caches);
  out_envs:
  	kfree(cl_envs);
  out:
  	return result;
  }
  
  /**
   * Finalization of global cl-data. Dual to cl_global_init().
   */
  void cl_global_fini(void)
  {
  	cl_env_percpu_fini();
  	lu_context_key_degister(&cl_key);
  	lu_kmem_fini(cl_object_caches);
  	kfree(cl_envs);
  }
  