staging/lustre: Get rid of cl_env hash table

cl_env hash table is under heavy contention when there are lots of
processes doing IO at the same time;
reduce lock contention by replacing cl_env cache with percpu array;
remove cl_env_nested_get() and cl_env_nested_put();
remove cl_env_reenter() and cl_env_reexit();

Signed-off-by: Jinshan Xiong <jinshan.xiong@intel.com>
Reviewed-on: http://review.whamcloud.com/20254
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-4257
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Bobi Jam <bobijam@hotmail.com>
Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

18 files changed, 183 insertions, 537 deletions

diff --git a/drivers/staging/lustre/lustre/include/cl_object.h b/drivers/staging/lustre/lustre/include/cl_object.h
index 514d650cea4c..3fe26e79ca46 100644
--- a/drivers/staging/lustre/lustre/include/cl_object.h
+++ b/drivers/staging/lustre/lustre/include/cl_object.h
@@ -2640,35 +2640,13 @@ void cl_sync_io_end(const struct lu_env *env, struct cl_sync_io *anchor);
  *     - allocation and destruction of environment is amortized by caching no
  *     longer used environments instead of destroying them;
  *
- *     - there is a notion of "current" environment, attached to the kernel
- *     data structure representing current thread Top-level lustre code
- *     allocates an environment and makes it current, then calls into
- *     non-lustre code, that in turn calls lustre back. Low-level lustre
- *     code thus called can fetch environment created by the top-level code
- *     and reuse it, avoiding additional environment allocation.
- *       Right now, three interfaces can attach the cl_env to running thread:
- *       - cl_env_get
- *       - cl_env_implant
- *       - cl_env_reexit(cl_env_reenter had to be called priorly)
- *
  * \see lu_env, lu_context, lu_context_key
  * @{
  */
 
-struct cl_env_nest {
-	int   cen_refcheck;
-	void *cen_cookie;
-};
-
 struct lu_env *cl_env_get(int *refcheck);
 struct lu_env *cl_env_alloc(int *refcheck, __u32 tags);
-struct lu_env *cl_env_nested_get(struct cl_env_nest *nest);
 void cl_env_put(struct lu_env *env, int *refcheck);
-void cl_env_nested_put(struct cl_env_nest *nest, struct lu_env *env);
-void *cl_env_reenter(void);
-void cl_env_reexit(void *cookie);
-void cl_env_implant(struct lu_env *env, int *refcheck);
-void cl_env_unplant(struct lu_env *env, int *refcheck);
 unsigned int cl_env_cache_purge(unsigned int nr);
 struct lu_env *cl_env_percpu_get(void);
 void cl_env_percpu_put(struct lu_env *env);
diff --git a/drivers/staging/lustre/lustre/ldlm/ldlm_pool.c b/drivers/staging/lustre/lustre/ldlm/ldlm_pool.c
index b29c9561a712..19831c555c49 100644
--- a/drivers/staging/lustre/lustre/ldlm/ldlm_pool.c
+++ b/drivers/staging/lustre/lustre/ldlm/ldlm_pool.c
@@ -794,7 +794,6 @@ static unsigned long ldlm_pools_count(ldlm_side_t client, gfp_t gfp_mask)
 	int nr_ns;
 	struct ldlm_namespace *ns;
 	struct ldlm_namespace *ns_old = NULL; /* loop detection */
-	void *cookie;
 
 	if (client == LDLM_NAMESPACE_CLIENT && !(gfp_mask & __GFP_FS))
 		return 0;
@@ -802,8 +801,6 @@ static unsigned long ldlm_pools_count(ldlm_side_t client, gfp_t gfp_mask)
 	CDEBUG(D_DLMTRACE, "Request to count %s locks from all pools\n",
 	       client == LDLM_NAMESPACE_CLIENT ? "client" : "server");
 
-	cookie = cl_env_reenter();
-
 	/*
 	 * Find out how many resources we may release.
 	 */
@@ -812,7 +809,6 @@ static unsigned long ldlm_pools_count(ldlm_side_t client, gfp_t gfp_mask)
 		mutex_lock(ldlm_namespace_lock(client));
 		if (list_empty(ldlm_namespace_list(client))) {
 			mutex_unlock(ldlm_namespace_lock(client));
-			cl_env_reexit(cookie);
 			return 0;
 		}
 		ns = ldlm_namespace_first_locked(client);
@@ -838,7 +834,6 @@ static unsigned long ldlm_pools_count(ldlm_side_t client, gfp_t gfp_mask)
 		ldlm_namespace_put(ns);
 	}
 
-	cl_env_reexit(cookie);
 	return total;
 }
 
@@ -847,13 +842,10 @@ static unsigned long ldlm_pools_scan(ldlm_side_t client, int nr, gfp_t gfp_mask)
 	unsigned long freed = 0;
 	int tmp, nr_ns;
 	struct ldlm_namespace *ns;
-	void *cookie;
 
 	if (client == LDLM_NAMESPACE_CLIENT && !(gfp_mask & __GFP_FS))
 		return -1;
 
-	cookie = cl_env_reenter();
-
 	/*
 	 * Shrink at least ldlm_namespace_nr_read(client) namespaces.
 	 */
@@ -883,7 +875,6 @@ static unsigned long ldlm_pools_scan(ldlm_side_t client, int nr, gfp_t gfp_mask)
 		freed += ldlm_pool_shrink(&ns->ns_pool, cancel, gfp_mask);
 		ldlm_namespace_put(ns);
 	}
-	cl_env_reexit(cookie);
 	/*
 	 * we only decrease the SLV in server pools shrinker, return
 	 * SHRINK_STOP to kernel to avoid needless loop. LU-1128
diff --git a/drivers/staging/lustre/lustre/llite/file.c b/drivers/staging/lustre/lustre/llite/file.c
index 0ae78c7c081d..c1c7551991e6 100644
--- a/drivers/staging/lustre/lustre/llite/file.c
+++ b/drivers/staging/lustre/lustre/llite/file.c
@@ -1584,11 +1584,11 @@ restart:
  */
 int ll_hsm_release(struct inode *inode)
 {
-	struct cl_env_nest nest;
 	struct lu_env *env;
 	struct obd_client_handle *och = NULL;
 	__u64 data_version = 0;
 	int rc;
+	int refcheck;
 
 	CDEBUG(D_INODE, "%s: Releasing file "DFID".\n",
 	       ll_get_fsname(inode->i_sb, NULL, 0),
@@ -1605,14 +1605,14 @@ int ll_hsm_release(struct inode *inode)
 	if (rc != 0)
 		goto out;
 
-	env = cl_env_nested_get(&nest);
+	env = cl_env_get(&refcheck);
 	if (IS_ERR(env)) {
 		rc = PTR_ERR(env);
 		goto out;
 	}
 
 	ll_merge_attr(env, inode);
-	cl_env_nested_put(&nest, env);
+	cl_env_put(env, &refcheck);
 
 	/* Release the file.
 	 * NB: lease lock handle is released in mdc_hsm_release_pack() because
@@ -2268,17 +2268,17 @@ static int ll_flush(struct file *file, fl_owner_t id)
 int cl_sync_file_range(struct inode *inode, loff_t start, loff_t end,
 		       enum cl_fsync_mode mode, int ignore_layout)
 {
-	struct cl_env_nest nest;
 	struct lu_env *env;
 	struct cl_io *io;
 	struct cl_fsync_io *fio;
 	int result;
+	int refcheck;
 
 	if (mode != CL_FSYNC_NONE && mode != CL_FSYNC_LOCAL &&
 	    mode != CL_FSYNC_DISCARD && mode != CL_FSYNC_ALL)
 		return -EINVAL;
 
-	env = cl_env_nested_get(&nest);
+	env = cl_env_get(&refcheck);
 	if (IS_ERR(env))
 		return PTR_ERR(env);
 
@@ -2301,7 +2301,7 @@ int cl_sync_file_range(struct inode *inode, loff_t start, loff_t end,
 	if (result == 0)
 		result = fio->fi_nr_written;
 	cl_io_fini(env, io);
-	cl_env_nested_put(&nest, env);
+	cl_env_put(env, &refcheck);
 
 	return result;
 }
@@ -3149,14 +3149,14 @@ int ll_layout_conf(struct inode *inode, const struct cl_object_conf *conf)
 {
 	struct ll_inode_info *lli = ll_i2info(inode);
 	struct cl_object *obj = lli->lli_clob;
-	struct cl_env_nest nest;
 	struct lu_env *env;
 	int rc;
+	int refcheck;
 
 	if (!obj)
 		return 0;
 
-	env = cl_env_nested_get(&nest);
+	env = cl_env_get(&refcheck);
 	if (IS_ERR(env))
 		return PTR_ERR(env);
 
@@ -3190,7 +3190,7 @@ int ll_layout_conf(struct inode *inode, const struct cl_object_conf *conf)
 		ll_layout_version_set(lli, cl.cl_layout_gen);
 	}
 out:
-	cl_env_nested_put(&nest, env);
+	cl_env_put(env, &refcheck);
 	return rc;
 }
 
diff --git a/drivers/staging/lustre/lustre/llite/lcommon_cl.c b/drivers/staging/lustre/lustre/llite/lcommon_cl.c
index 56e414b1d10f..dd1cfd8f5213 100644
--- a/drivers/staging/lustre/lustre/llite/lcommon_cl.c
+++ b/drivers/staging/lustre/lustre/llite/lcommon_cl.c
@@ -246,15 +246,11 @@ void cl_inode_fini(struct inode *inode)
 	int emergency;
 
 	if (clob) {
-		void		    *cookie;
-
-		cookie = cl_env_reenter();
 		env = cl_env_get(&refcheck);
 		emergency = IS_ERR(env);
 		if (emergency) {
 			mutex_lock(&cl_inode_fini_guard);
 			LASSERT(cl_inode_fini_env);
-			cl_env_implant(cl_inode_fini_env, &refcheck);
 			env = cl_inode_fini_env;
 		}
 		/*
@@ -266,13 +262,10 @@ void cl_inode_fini(struct inode *inode)
 		lu_object_ref_del(&clob->co_lu, "inode", inode);
 		cl_object_put_last(env, clob);
 		lli->lli_clob = NULL;
-		if (emergency) {
-			cl_env_unplant(cl_inode_fini_env, &refcheck);
+		if (emergency)
 			mutex_unlock(&cl_inode_fini_guard);
-		} else {
+		else
 			cl_env_put(env, &refcheck);
-		}
-		cl_env_reexit(cookie);
 	}
 }
 
diff --git a/drivers/staging/lustre/lustre/llite/lcommon_misc.c b/drivers/staging/lustre/lustre/llite/lcommon_misc.c
index 1558b55363d4..f48660ed350f 100644
--- a/drivers/staging/lustre/lustre/llite/lcommon_misc.c
+++ b/drivers/staging/lustre/lustre/llite/lcommon_misc.c
@@ -162,13 +162,11 @@ int cl_get_grouplock(struct cl_object *obj, unsigned long gid, int nonblock,
 		return rc;
 	}
 
-	cg->lg_env  = cl_env_get(&refcheck);
+	cg->lg_env  = env;
 	cg->lg_io   = io;
 	cg->lg_lock = lock;
 	cg->lg_gid  = gid;
-	LASSERT(cg->lg_env == env);
 
-	cl_env_unplant(env, &refcheck);
 	return 0;
 }
 
@@ -177,14 +175,10 @@ void cl_put_grouplock(struct ll_grouplock *cg)
 	struct lu_env  *env  = cg->lg_env;
 	struct cl_io   *io   = cg->lg_io;
 	struct cl_lock *lock = cg->lg_lock;
-	int	     refcheck;
 
 	LASSERT(cg->lg_env);
 	LASSERT(cg->lg_gid);
 
-	cl_env_implant(env, &refcheck);
-	cl_env_put(env, &refcheck);
-
 	cl_lock_release(env, lock);
 	cl_io_fini(env, io);
 	cl_env_put(env, NULL);
diff --git a/drivers/staging/lustre/lustre/llite/llite_mmap.c b/drivers/staging/lustre/lustre/llite/llite_mmap.c
index 436691814a5e..ad2a699ea2f5 100644
--- a/drivers/staging/lustre/lustre/llite/llite_mmap.c
+++ b/drivers/staging/lustre/lustre/llite/llite_mmap.c
@@ -80,43 +80,24 @@ struct vm_area_struct *our_vma(struct mm_struct *mm, unsigned long addr,
  * API independent part for page fault initialization.
  * \param vma - virtual memory area addressed to page fault
  * \param env - corespondent lu_env to processing
- * \param nest - nested level
  * \param index - page index corespondent to fault.
  * \parm ra_flags - vma readahead flags.
  *
- * \return allocated and initialized env for fault operation.
- * \retval EINVAL if env can't allocated
- * \return other error codes from cl_io_init.
+ * \return error codes from cl_io_init.
  */
 static struct cl_io *
-ll_fault_io_init(struct vm_area_struct *vma, struct lu_env **env_ret,
-		 struct cl_env_nest *nest, pgoff_t index,
-		 unsigned long *ra_flags)
+ll_fault_io_init(struct lu_env *env, struct vm_area_struct *vma,
+		 pgoff_t index, unsigned long *ra_flags)
 {
 	struct file	       *file = vma->vm_file;
 	struct inode	       *inode = file_inode(file);
 	struct cl_io	       *io;
 	struct cl_fault_io     *fio;
-	struct lu_env	       *env;
 	int			rc;
 
-	*env_ret = NULL;
 	if (ll_file_nolock(file))
 		return ERR_PTR(-EOPNOTSUPP);
 
-	/*
-	 * page fault can be called when lustre IO is
-	 * already active for the current thread, e.g., when doing read/write
-	 * against user level buffer mapped from Lustre buffer. To avoid
-	 * stomping on existing context, optionally force an allocation of a new
-	 * one.
-	 */
-	env = cl_env_nested_get(nest);
-	if (IS_ERR(env))
-		return ERR_PTR(-EINVAL);
-
-	*env_ret = env;
-
 restart:
 	io = vvp_env_thread_io(env);
 	io->ci_obj = ll_i2info(inode)->lli_clob;
@@ -155,7 +136,6 @@ restart:
 		if (io->ci_need_restart)
 			goto restart;
 
-		cl_env_nested_put(nest, env);
 		io = ERR_PTR(rc);
 	}
 
@@ -169,13 +149,17 @@ static int ll_page_mkwrite0(struct vm_area_struct *vma, struct page *vmpage,
 	struct lu_env	   *env;
 	struct cl_io	    *io;
 	struct vvp_io	   *vio;
-	struct cl_env_nest       nest;
 	int		      result;
+	int refcheck;
 	sigset_t	     set;
 	struct inode	     *inode;
 	struct ll_inode_info     *lli;
 
-	io = ll_fault_io_init(vma, &env,  &nest, vmpage->index, NULL);
+	env = cl_env_get(&refcheck);
+	if (IS_ERR(env))
+		return PTR_ERR(env);
+
+	io = ll_fault_io_init(env, vma, vmpage->index, NULL);
 	if (IS_ERR(io)) {
 		result = PTR_ERR(io);
 		goto out;
@@ -240,8 +224,8 @@ static int ll_page_mkwrite0(struct vm_area_struct *vma, struct page *vmpage,
 
 out_io:
 	cl_io_fini(env, io);
-	cl_env_nested_put(&nest, env);
 out:
+	cl_env_put(env, &refcheck);
 	CDEBUG(D_MMAP, "%s mkwrite with %d\n", current->comm, result);
 	LASSERT(ergo(result == 0, PageLocked(vmpage)));
 
@@ -285,13 +269,19 @@ static int ll_fault0(struct vm_area_struct *vma, struct vm_fault *vmf)
 	struct vvp_io	   *vio = NULL;
 	struct page	     *vmpage;
 	unsigned long	    ra_flags;
-	struct cl_env_nest       nest;
-	int		      result;
+	int		      result = 0;
 	int		      fault_ret = 0;
+	int refcheck;
 
-	io = ll_fault_io_init(vma, &env,  &nest, vmf->pgoff, &ra_flags);
-	if (IS_ERR(io))
-		return to_fault_error(PTR_ERR(io));
+	env = cl_env_get(&refcheck);
+	if (IS_ERR(env))
+		return PTR_ERR(env);
+
+	io = ll_fault_io_init(env, vma, vmf->pgoff, &ra_flags);
+	if (IS_ERR(io)) {
+		result = to_fault_error(PTR_ERR(io));
+		goto out;
+	}
 
 	result = io->ci_result;
 	if (result == 0) {
@@ -322,14 +312,15 @@ static int ll_fault0(struct vm_area_struct *vma, struct vm_fault *vmf)
 		}
 	}
 	cl_io_fini(env, io);
-	cl_env_nested_put(&nest, env);
 
 	vma->vm_flags |= ra_flags;
+
+out:
+	cl_env_put(env, &refcheck);
 	if (result != 0 && !(fault_ret & VM_FAULT_RETRY))
 		fault_ret |= to_fault_error(result);
 
-	CDEBUG(D_MMAP, "%s fault %d/%d\n",
-	       current->comm, fault_ret, result);
+	CDEBUG(D_MMAP, "%s fault %d/%d\n", current->comm, fault_ret, result);
 	return fault_ret;
 }
 
diff --git a/drivers/staging/lustre/lustre/llite/rw.c b/drivers/staging/lustre/lustre/llite/rw.c
index 80cb8e0d6666..d2515a8005d3 100644
--- a/drivers/staging/lustre/lustre/llite/rw.c
+++ b/drivers/staging/lustre/lustre/llite/rw.c
@@ -896,17 +896,17 @@ int ll_writepage(struct page *vmpage, struct writeback_control *wbc)
 	struct cl_io	   *io;
 	struct cl_page	 *page;
 	struct cl_object       *clob;
-	struct cl_env_nest      nest;
 	bool redirtied = false;
 	bool unlocked = false;
 	int result;
+	int refcheck;
 
 	LASSERT(PageLocked(vmpage));
 	LASSERT(!PageWriteback(vmpage));
 
 	LASSERT(ll_i2dtexp(inode));
 
-	env = cl_env_nested_get(&nest);
+	env = cl_env_get(&refcheck);
 	if (IS_ERR(env)) {
 		result = PTR_ERR(env);
 		goto out;
@@ -971,7 +971,7 @@ int ll_writepage(struct page *vmpage, struct writeback_control *wbc)
 		}
 	}
 
-	cl_env_nested_put(&nest, env);
+	cl_env_put(env, &refcheck);
 	goto out;
 
 out:
diff --git a/drivers/staging/lustre/lustre/llite/rw26.c b/drivers/staging/lustre/lustre/llite/rw26.c
index 67010beab8f1..1a08a9d526e8 100644
--- a/drivers/staging/lustre/lustre/llite/rw26.c
+++ b/drivers/staging/lustre/lustre/llite/rw26.c
@@ -103,7 +103,6 @@ static void ll_invalidatepage(struct page *vmpage, unsigned int offset,
 static int ll_releasepage(struct page *vmpage, gfp_t gfp_mask)
 {
 	struct lu_env     *env;
-	void			*cookie;
 	struct cl_object  *obj;
 	struct cl_page    *page;
 	struct address_space *mapping;
@@ -129,7 +128,6 @@ static int ll_releasepage(struct page *vmpage, gfp_t gfp_mask)
 	if (!page)
 		return 1;
 
-	cookie = cl_env_reenter();
 	env = cl_env_percpu_get();
 	LASSERT(!IS_ERR(env));
 
@@ -155,7 +153,6 @@ static int ll_releasepage(struct page *vmpage, gfp_t gfp_mask)
 	cl_page_put(env, page);
 
 	cl_env_percpu_put(env);
-	cl_env_reexit(cookie);
 	return result;
 }
 
@@ -340,7 +337,8 @@ static ssize_t ll_direct_IO_26_seg(const struct lu_env *env, struct cl_io *io,
 		       PAGE_SIZE) & ~(DT_MAX_BRW_SIZE - 1))
 static ssize_t ll_direct_IO_26(struct kiocb *iocb, struct iov_iter *iter)
 {
-	struct lu_env *env;
+	struct ll_cl_context *lcc;
+	const struct lu_env *env;
 	struct cl_io *io;
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file->f_mapping->host;
@@ -348,7 +346,6 @@ static ssize_t ll_direct_IO_26(struct kiocb *iocb, struct iov_iter *iter)
 	ssize_t count = iov_iter_count(iter);
 	ssize_t tot_bytes = 0, result = 0;
 	long size = MAX_DIO_SIZE;
-	int refcheck;
 
 	/* FIXME: io smaller than PAGE_SIZE is broken on ia64 ??? */
 	if ((file_offset & ~PAGE_MASK) || (count & ~PAGE_MASK))
@@ -363,9 +360,13 @@ static ssize_t ll_direct_IO_26(struct kiocb *iocb, struct iov_iter *iter)
 	if (iov_iter_alignment(iter) & ~PAGE_MASK)
 		return -EINVAL;
 
-	env = cl_env_get(&refcheck);
+	lcc = ll_cl_find(file);
+	if (!lcc)
+		return -EIO;
+
+	env = lcc->lcc_env;
 	LASSERT(!IS_ERR(env));
-	io = vvp_env_io(env)->vui_cl.cis_io;
+	io = lcc->lcc_io;
 	LASSERT(io);
 
 	while (iov_iter_count(iter)) {
@@ -422,7 +423,6 @@ out:
 		vio->u.write.vui_written += tot_bytes;
 	}
 
-	cl_env_put(env, &refcheck);
 	return tot_bytes ? tot_bytes : result;
 }
 
diff --git a/drivers/staging/lustre/lustre/lov/lov_io.c b/drivers/staging/lustre/lustre/lov/lov_io.c
index 011ab0f3ccc1..002326c282a7 100644
--- a/drivers/staging/lustre/lustre/lov/lov_io.c
+++ b/drivers/staging/lustre/lustre/lov/lov_io.c
@@ -167,12 +167,7 @@ static int lov_io_sub_init(const struct lu_env *env, struct lov_io *lio,
 		sub->sub_env = ld->ld_emrg[stripe]->emrg_env;
 		sub->sub_borrowed = 1;
 	} else {
-		void *cookie;
-
-		/* obtain new environment */
-		cookie = cl_env_reenter();
 		sub->sub_env = cl_env_get(&sub->sub_refcheck);
-		cl_env_reexit(cookie);
 		if (IS_ERR(sub->sub_env))
 			result = PTR_ERR(sub->sub_env);
 
diff --git a/drivers/staging/lustre/lustre/lov/lov_object.c b/drivers/staging/lustre/lustre/lov/lov_object.c
index 711a3b96d90e..317311ccf2c2 100644
--- a/drivers/staging/lustre/lustre/lov/lov_object.c
+++ b/drivers/staging/lustre/lustre/lov/lov_object.c
@@ -729,19 +729,15 @@ static int lov_layout_change(const struct lu_env *unused,
 	union lov_layout_state *state = &lov->u;
 	const struct lov_layout_operations *old_ops;
 	const struct lov_layout_operations *new_ops;
-	void *cookie;
 	struct lu_env *env;
 	int refcheck;
 	int rc;
 
 	LASSERT(0 <= lov->lo_type && lov->lo_type < ARRAY_SIZE(lov_dispatch));
 
-	cookie = cl_env_reenter();
 	env = cl_env_get(&refcheck);
-	if (IS_ERR(env)) {
-		cl_env_reexit(cookie);
+	if (IS_ERR(env))
 		return PTR_ERR(env);
-	}
 
 	LASSERT(0 <= llt && llt < ARRAY_SIZE(lov_dispatch));
 
@@ -782,7 +778,6 @@ static int lov_layout_change(const struct lu_env *unused,
 	lov->lo_type = llt;
 out:
 	cl_env_put(env, &refcheck);
-	cl_env_reexit(cookie);
 	return rc;
 }
 
diff --git a/drivers/staging/lustre/lustre/obdclass/cl_internal.h b/drivers/staging/lustre/lustre/obdclass/cl_internal.h
index e866754a42d5..7b403fbd5f94 100644
--- a/drivers/staging/lustre/lustre/obdclass/cl_internal.h
+++ b/drivers/staging/lustre/lustre/obdclass/cl_internal.h
@@ -50,25 +50,6 @@ enum clt_nesting_level {
 };
 
 /**
- * Counters used to check correctness of cl_lock interface usage.
- */
-struct cl_thread_counters {
-	/**
-	 * Number of outstanding calls to cl_lock_mutex_get() made by the
-	 * current thread. For debugging.
-	 */
-	int	   ctc_nr_locks_locked;
-	/** List of locked locks. */
-	struct lu_ref ctc_locks_locked;
-	/** Number of outstanding holds on locks. */
-	int	   ctc_nr_held;
-	/** Number of outstanding uses on locks. */
-	int	   ctc_nr_used;
-	/** Number of held extent locks. */
-	int	   ctc_nr_locks_acquired;
-};
-
-/**
  * Thread local state internal for generic cl-code.
  */
 struct cl_thread_info {
@@ -83,10 +64,6 @@ struct cl_thread_info {
 	 */
 	struct cl_lock_descr clt_descr;
 	struct cl_page_list  clt_list;
-	/**
-	 * Counters for every level of lock nesting.
-	 */
-	struct cl_thread_counters clt_counters[CNL_NR];
 	/** @} debugging */
 
 	/*
diff --git a/drivers/staging/lustre/lustre/obdclass/cl_io.c b/drivers/staging/lustre/lustre/obdclass/cl_io.c
index c5621adeef86..af8e4d618421 100644
--- a/drivers/staging/lustre/lustre/obdclass/cl_io.c
+++ b/drivers/staging/lustre/lustre/obdclass/cl_io.c
@@ -412,7 +412,6 @@ void cl_io_unlock(const struct lu_env *env, struct cl_io *io)
 			scan->cis_iop->op[io->ci_type].cio_unlock(env, scan);
 	}
 	io->ci_state = CIS_UNLOCKED;
-	LASSERT(!cl_env_info(env)->clt_counters[CNL_TOP].ctc_nr_locks_acquired);
 }
 EXPORT_SYMBOL(cl_io_unlock);
 
diff --git a/drivers/staging/lustre/lustre/obdclass/cl_object.c b/drivers/staging/lustre/lustre/obdclass/cl_object.c
index b4600c449c2d..f5d4e23c64b7 100644
--- a/drivers/staging/lustre/lustre/obdclass/cl_object.c
+++ b/drivers/staging/lustre/lustre/obdclass/cl_object.c
@@ -544,36 +544,20 @@ EXPORT_SYMBOL(cl_site_stats_print);
  * bz20044, bz22683.
  */
 
-static LIST_HEAD(cl_envs);
-static unsigned int cl_envs_cached_nr;
-static unsigned int cl_envs_cached_max = 128; /* XXX: prototype: arbitrary limit
-					       * for now.
-					       */
-static DEFINE_SPINLOCK(cl_envs_guard);
+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;
 
-	/**
-	 * This allows cl_env to be entered into cl_env_hash which implements
-	 * the current thread -> client environment lookup.
-	 */
-	struct hlist_node  ce_node;
-	/**
-	 * Owner for the current cl_env.
-	 *
-	 * If LL_TASK_CL_ENV is defined, this point to the owning current,
-	 * only for debugging purpose ;
-	 * Otherwise hash is used, and this is the key for cfs_hash.
-	 * Now current thread pid is stored. Note using thread pointer would
-	 * lead to unbalanced hash because of its specific allocation locality
-	 * and could be varied for different platforms and OSes, even different
-	 * OS versions.
-	 */
-	void	     *ce_owner;
-
 	/*
 	 * Linkage into global list of all client environments. Used for
 	 * garbage collection.
@@ -597,122 +581,13 @@ 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_owner);
+	LASSERT(!cle->ce_debug);
 
 	cle->ce_ref = 1;
 	cle->ce_debug = debug;
 	CL_ENV_INC(busy);
 }
 
-/*
- * The implementation of using hash table to connect cl_env and thread
- */
-
-static struct cfs_hash *cl_env_hash;
-
-static unsigned cl_env_hops_hash(struct cfs_hash *lh,
-				 const void *key, unsigned mask)
-{
-#if BITS_PER_LONG == 64
-	return cfs_hash_u64_hash((__u64)key, mask);
-#else
-	return cfs_hash_u32_hash((__u32)key, mask);
-#endif
-}
-
-static void *cl_env_hops_obj(struct hlist_node *hn)
-{
-	struct cl_env *cle = hlist_entry(hn, struct cl_env, ce_node);
-
-	LASSERT(cle->ce_magic == &cl_env_init0);
-	return (void *)cle;
-}
-
-static int cl_env_hops_keycmp(const void *key, struct hlist_node *hn)
-{
-	struct cl_env *cle = cl_env_hops_obj(hn);
-
-	LASSERT(cle->ce_owner);
-	return (key == cle->ce_owner);
-}
-
-static void cl_env_hops_noop(struct cfs_hash *hs, struct hlist_node *hn)
-{
-	struct cl_env *cle = hlist_entry(hn, struct cl_env, ce_node);
-
-	LASSERT(cle->ce_magic == &cl_env_init0);
-}
-
-static struct cfs_hash_ops cl_env_hops = {
-	.hs_hash	= cl_env_hops_hash,
-	.hs_key		= cl_env_hops_obj,
-	.hs_keycmp      = cl_env_hops_keycmp,
-	.hs_object      = cl_env_hops_obj,
-	.hs_get		= cl_env_hops_noop,
-	.hs_put_locked  = cl_env_hops_noop,
-};
-
-static inline struct cl_env *cl_env_fetch(void)
-{
-	struct cl_env *cle;
-
-	cle = cfs_hash_lookup(cl_env_hash, (void *)(long)current->pid);
-	LASSERT(ergo(cle, cle->ce_magic == &cl_env_init0));
-	return cle;
-}
-
-static inline void cl_env_attach(struct cl_env *cle)
-{
-	if (cle) {
-		int rc;
-
-		LASSERT(!cle->ce_owner);
-		cle->ce_owner = (void *)(long)current->pid;
-		rc = cfs_hash_add_unique(cl_env_hash, cle->ce_owner,
-					 &cle->ce_node);
-		LASSERT(rc == 0);
-	}
-}
-
-static inline void cl_env_do_detach(struct cl_env *cle)
-{
-	void *cookie;
-
-	LASSERT(cle->ce_owner == (void *)(long)current->pid);
-	cookie = cfs_hash_del(cl_env_hash, cle->ce_owner,
-			      &cle->ce_node);
-	LASSERT(cookie == cle);
-	cle->ce_owner = NULL;
-}
-
-static int cl_env_store_init(void)
-{
-	cl_env_hash = cfs_hash_create("cl_env",
-				      HASH_CL_ENV_BITS, HASH_CL_ENV_BITS,
-				      HASH_CL_ENV_BKT_BITS, 0,
-				      CFS_HASH_MIN_THETA,
-				      CFS_HASH_MAX_THETA,
-				      &cl_env_hops,
-				      CFS_HASH_RW_BKTLOCK);
-	return cl_env_hash ? 0 : -ENOMEM;
-}
-
-static void cl_env_store_fini(void)
-{
-	cfs_hash_putref(cl_env_hash);
-}
-
-static inline struct cl_env *cl_env_detach(struct cl_env *cle)
-{
-	if (!cle)
-		cle = cl_env_fetch();
-
-	if (cle && cle->ce_owner)
-		cl_env_do_detach(cle);
-
-	return cle;
-}
-
 static struct lu_env *cl_env_new(__u32 ctx_tags, __u32 ses_tags, void *debug)
 {
 	struct lu_env *env;
@@ -762,16 +637,20 @@ static struct lu_env *cl_env_obtain(void *debug)
 {
 	struct cl_env *cle;
 	struct lu_env *env;
+	int cpu = get_cpu();
 
-	spin_lock(&cl_envs_guard);
-	LASSERT(equi(cl_envs_cached_nr == 0, list_empty(&cl_envs)));
-	if (cl_envs_cached_nr > 0) {
+	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.next, struct cl_env, ce_linkage);
+		cle = container_of(cl_envs[cpu].cec_envs.next, struct cl_env,
+				   ce_linkage);
 		list_del_init(&cle->ce_linkage);
-		cl_envs_cached_nr--;
-		spin_unlock(&cl_envs_guard);
+		cl_envs[cpu].cec_count--;
+		read_unlock(&cl_envs[cpu].cec_guard);
+		put_cpu();
 
 		env = &cle->ce_lu;
 		rc = lu_env_refill(env);
@@ -784,7 +663,8 @@ static struct lu_env *cl_env_obtain(void *debug)
 			env = ERR_PTR(rc);
 		}
 	} else {
-		spin_unlock(&cl_envs_guard);
+		read_unlock(&cl_envs[cpu].cec_guard);
+		put_cpu();
 		env = cl_env_new(lu_context_tags_default,
 				 lu_session_tags_default, debug);
 	}
@@ -796,27 +676,6 @@ static inline struct cl_env *cl_env_container(struct lu_env *env)
 	return container_of(env, struct cl_env, ce_lu);
 }
 
-static struct lu_env *cl_env_peek(int *refcheck)
-{
-	struct lu_env *env;
-	struct cl_env *cle;
-
-	CL_ENV_INC(lookup);
-
-	/* check that we don't go far from untrusted pointer */
-	CLASSERT(offsetof(struct cl_env, ce_magic) == 0);
-
-	env = NULL;
-	cle = cl_env_fetch();
-	if (cle) {
-		CL_ENV_INC(hit);
-		env = &cle->ce_lu;
-		*refcheck = ++cle->ce_ref;
-	}
-	CDEBUG(D_OTHER, "%d@%p\n", cle ? cle->ce_ref : 0, cle);
-	return env;
-}
-
 /**
  * Returns lu_env: if there already is an environment associated with the
  * current thread, it is returned, otherwise, new environment is allocated.
@@ -834,17 +693,13 @@ struct lu_env *cl_env_get(int *refcheck)
 {
 	struct lu_env *env;
 
-	env = cl_env_peek(refcheck);
-	if (!env) {
-		env = cl_env_obtain(__builtin_return_address(0));
-		if (!IS_ERR(env)) {
-			struct cl_env *cle;
+	env = cl_env_obtain(__builtin_return_address(0));
+	if (!IS_ERR(env)) {
+		struct cl_env *cle;
 
-			cle = cl_env_container(env);
-			cl_env_attach(cle);
-			*refcheck = cle->ce_ref;
-			CDEBUG(D_OTHER, "%d@%p\n", cle->ce_ref, cle);
-		}
+		cle = cl_env_container(env);
+		*refcheck = cle->ce_ref;
+		CDEBUG(D_OTHER, "%d@%p\n", cle->ce_ref, cle);
 	}
 	return env;
 }
@@ -859,7 +714,6 @@ struct lu_env *cl_env_alloc(int *refcheck, __u32 tags)
 {
 	struct lu_env *env;
 
-	LASSERT(!cl_env_peek(refcheck));
 	env = cl_env_new(tags, tags, __builtin_return_address(0));
 	if (!IS_ERR(env)) {
 		struct cl_env *cle;
@@ -874,7 +728,6 @@ EXPORT_SYMBOL(cl_env_alloc);
 
 static void cl_env_exit(struct cl_env *cle)
 {
-	LASSERT(!cle->ce_owner);
 	lu_context_exit(&cle->ce_lu.le_ctx);
 	lu_context_exit(&cle->ce_ses);
 }
@@ -887,20 +740,25 @@ static void cl_env_exit(struct cl_env *cle)
 unsigned int cl_env_cache_purge(unsigned int nr)
 {
 	struct cl_env *cle;
+	unsigned int i;
 
-	spin_lock(&cl_envs_guard);
-	for (; !list_empty(&cl_envs) && nr > 0; --nr) {
-		cle = container_of(cl_envs.next, struct cl_env, ce_linkage);
-		list_del_init(&cle->ce_linkage);
-		LASSERT(cl_envs_cached_nr > 0);
-		cl_envs_cached_nr--;
-		spin_unlock(&cl_envs_guard);
+	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);
-		spin_lock(&cl_envs_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);
 	}
-	LASSERT(equi(cl_envs_cached_nr == 0, list_empty(&cl_envs)));
-	spin_unlock(&cl_envs_guard);
 	return nr;
 }
 EXPORT_SYMBOL(cl_env_cache_purge);
@@ -923,8 +781,9 @@ void cl_env_put(struct lu_env *env, int *refcheck)
 
 	CDEBUG(D_OTHER, "%d@%p\n", cle->ce_ref, cle);
 	if (--cle->ce_ref == 0) {
+		int cpu = get_cpu();
+
 		CL_ENV_DEC(busy);
-		cl_env_detach(cle);
 		cle->ce_debug = NULL;
 		cl_env_exit(cle);
 		/*
@@ -933,107 +792,22 @@ void cl_env_put(struct lu_env *env, int *refcheck)
 		 * Return environment to the cache only when it was allocated
 		 * with the standard tags.
 		 */
-		if (cl_envs_cached_nr < cl_envs_cached_max &&
+		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) {
-			spin_lock(&cl_envs_guard);
-			list_add(&cle->ce_linkage, &cl_envs);
-			cl_envs_cached_nr++;
-			spin_unlock(&cl_envs_guard);
+			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);
 
 /**
- * Declares a point of re-entrancy.
- *
- * \see cl_env_reexit()
- */
-void *cl_env_reenter(void)
-{
-	return cl_env_detach(NULL);
-}
-EXPORT_SYMBOL(cl_env_reenter);
-
-/**
- * Exits re-entrancy.
- */
-void cl_env_reexit(void *cookie)
-{
-	cl_env_detach(NULL);
-	cl_env_attach(cookie);
-}
-EXPORT_SYMBOL(cl_env_reexit);
-
-/**
- * Setup user-supplied \a env as a current environment. This is to be used to
- * guaranteed that environment exists even when cl_env_get() fails. It is up
- * to user to ensure proper concurrency control.
- *
- * \see cl_env_unplant()
- */
-void cl_env_implant(struct lu_env *env, int *refcheck)
-{
-	struct cl_env *cle = cl_env_container(env);
-
-	LASSERT(cle->ce_ref > 0);
-
-	cl_env_attach(cle);
-	cl_env_get(refcheck);
-	CDEBUG(D_OTHER, "%d@%p\n", cle->ce_ref, cle);
-}
-EXPORT_SYMBOL(cl_env_implant);
-
-/**
- * Detach environment installed earlier by cl_env_implant().
- */
-void cl_env_unplant(struct lu_env *env, int *refcheck)
-{
-	struct cl_env *cle = cl_env_container(env);
-
-	LASSERT(cle->ce_ref > 1);
-
-	CDEBUG(D_OTHER, "%d@%p\n", cle->ce_ref, cle);
-
-	cl_env_detach(cle);
-	cl_env_put(env, refcheck);
-}
-EXPORT_SYMBOL(cl_env_unplant);
-
-struct lu_env *cl_env_nested_get(struct cl_env_nest *nest)
-{
-	struct lu_env *env;
-
-	nest->cen_cookie = NULL;
-	env = cl_env_peek(&nest->cen_refcheck);
-	if (env) {
-		if (!cl_io_is_going(env))
-			return env;
-		cl_env_put(env, &nest->cen_refcheck);
-		nest->cen_cookie = cl_env_reenter();
-	}
-	env = cl_env_get(&nest->cen_refcheck);
-	if (IS_ERR(env)) {
-		cl_env_reexit(nest->cen_cookie);
-		return env;
-	}
-
-	LASSERT(!cl_io_is_going(env));
-	return env;
-}
-EXPORT_SYMBOL(cl_env_nested_get);
-
-void cl_env_nested_put(struct cl_env_nest *nest, struct lu_env *env)
-{
-	cl_env_put(env, &nest->cen_refcheck);
-	cl_env_reexit(nest->cen_cookie);
-}
-EXPORT_SYMBOL(cl_env_nested_put);
-
-/**
  * Converts struct ost_lvb to struct cl_attr.
  *
  * \see cl_attr2lvb
@@ -1060,6 +834,10 @@ static int cl_env_percpu_init(void)
 	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;
 
@@ -1127,7 +905,6 @@ void cl_env_percpu_put(struct lu_env *env)
 	LASSERT(cle->ce_ref == 0);
 
 	CL_ENV_DEC(busy);
-	cl_env_detach(cle);
 	cle->ce_debug = NULL;
 
 	put_cpu();
@@ -1141,7 +918,6 @@ struct lu_env *cl_env_percpu_get(void)
 	cle = &cl_env_percpu[get_cpu()];
 	cl_env_init0(cle, __builtin_return_address(0));
 
-	cl_env_attach(cle);
 	return &cle->ce_lu;
 }
 EXPORT_SYMBOL(cl_env_percpu_get);
@@ -1205,51 +981,19 @@ LU_KEY_INIT_FINI(cl0, struct cl_thread_info);
 static void *cl_key_init(const struct lu_context *ctx,
 			 struct lu_context_key *key)
 {
-	struct cl_thread_info *info;
-
-	info = cl0_key_init(ctx, key);
-	if (!IS_ERR(info)) {
-		size_t i;
-
-		for (i = 0; i < ARRAY_SIZE(info->clt_counters); ++i)
-			lu_ref_init(&info->clt_counters[i].ctc_locks_locked);
-	}
-	return info;
+	return cl0_key_init(ctx, key);
 }
 
 static void cl_key_fini(const struct lu_context *ctx,
 			struct lu_context_key *key, void *data)
 {
-	struct cl_thread_info *info;
-	size_t i;
-
-	info = data;
-	for (i = 0; i < ARRAY_SIZE(info->clt_counters); ++i)
-		lu_ref_fini(&info->clt_counters[i].ctc_locks_locked);
 	cl0_key_fini(ctx, key, data);
 }
 
-static void cl_key_exit(const struct lu_context *ctx,
-			struct lu_context_key *key, void *data)
-{
-	struct cl_thread_info *info = data;
-	size_t i;
-
-	for (i = 0; i < ARRAY_SIZE(info->clt_counters); ++i) {
-		LASSERT(info->clt_counters[i].ctc_nr_held == 0);
-		LASSERT(info->clt_counters[i].ctc_nr_used == 0);
-		LASSERT(info->clt_counters[i].ctc_nr_locks_acquired == 0);
-		LASSERT(info->clt_counters[i].ctc_nr_locks_locked == 0);
-		lu_ref_fini(&info->clt_counters[i].ctc_locks_locked);
-		lu_ref_init(&info->clt_counters[i].ctc_locks_locked);
-	}
-}
-
 static struct lu_context_key cl_key = {
 	.lct_tags = LCT_CL_THREAD,
 	.lct_init = cl_key_init,
 	.lct_fini = cl_key_fini,
-	.lct_exit = cl_key_exit
 };
 
 static struct lu_kmem_descr cl_object_caches[] = {
@@ -1273,13 +1017,15 @@ int cl_global_init(void)
 {
 	int result;
 
-	result = cl_env_store_init();
-	if (result)
-		return result;
+	cl_envs = kzalloc(sizeof(*cl_envs) * num_possible_cpus(), GFP_KERNEL);
+	if (!cl_envs) {
+		result = -ENOMEM;
+		goto out;
+	}
 
 	result = lu_kmem_init(cl_object_caches);
 	if (result)
-		goto out_store;
+		goto out_envs;
 
 	LU_CONTEXT_KEY_INIT(&cl_key);
 	result = lu_context_key_register(&cl_key);
@@ -1289,16 +1035,17 @@ int cl_global_init(void)
 	result = cl_env_percpu_init();
 	if (result)
 		/* no cl_env_percpu_fini on error */
-		goto out_context;
+		goto out_keys;
 
 	return 0;
 
-out_context:
+out_keys:
 	lu_context_key_degister(&cl_key);
 out_kmem:
 	lu_kmem_fini(cl_object_caches);
-out_store:
-	cl_env_store_fini();
+out_envs:
+	kfree(cl_envs);
+out:
 	return result;
 }
 
@@ -1310,5 +1057,5 @@ void cl_global_fini(void)
 	cl_env_percpu_fini();
 	lu_context_key_degister(&cl_key);
 	lu_kmem_fini(cl_object_caches);
-	cl_env_store_fini();
+	kfree(cl_envs);
 }
diff --git a/drivers/staging/lustre/lustre/obdclass/lu_object.c b/drivers/staging/lustre/lustre/obdclass/lu_object.c
index e031fd297eb6..14ca82d46ba0 100644
--- a/drivers/staging/lustre/lustre/obdclass/lu_object.c
+++ b/drivers/staging/lustre/lustre/obdclass/lu_object.c
@@ -1521,10 +1521,6 @@ void lu_context_key_quiesce(struct lu_context_key *key)
 
 	if (!(key->lct_tags & LCT_QUIESCENT)) {
 		/*
-		 * XXX layering violation.
-		 */
-		cl_env_cache_purge(~0);
-		/*
 		 * XXX memory barrier has to go here.
 		 */
 		spin_lock(&lu_keys_guard);
diff --git a/drivers/staging/lustre/lustre/obdecho/echo_client.c b/drivers/staging/lustre/lustre/obdecho/echo_client.c
index 30caf5f5ec96..25ecfb3b32ad 100644
--- a/drivers/staging/lustre/lustre/obdecho/echo_client.c
+++ b/drivers/staging/lustre/lustre/obdecho/echo_client.c
@@ -563,16 +563,10 @@ static void echo_thread_key_fini(const struct lu_context *ctx,
 	kmem_cache_free(echo_thread_kmem, info);
 }
 
-static void echo_thread_key_exit(const struct lu_context *ctx,
-				 struct lu_context_key *key, void *data)
-{
-}
-
 static struct lu_context_key echo_thread_key = {
 	.lct_tags = LCT_CL_THREAD,
 	.lct_init = echo_thread_key_init,
 	.lct_fini = echo_thread_key_fini,
-	.lct_exit = echo_thread_key_exit
 };
 
 static void *echo_session_key_init(const struct lu_context *ctx,
@@ -594,16 +588,10 @@ static void echo_session_key_fini(const struct lu_context *ctx,
 	kmem_cache_free(echo_session_kmem, session);
 }
 
-static void echo_session_key_exit(const struct lu_context *ctx,
-				  struct lu_context_key *key, void *data)
-{
-}
-
 static struct lu_context_key echo_session_key = {
 	.lct_tags = LCT_SESSION,
 	.lct_init = echo_session_key_init,
 	.lct_fini = echo_session_key_fini,
-	.lct_exit = echo_session_key_exit
 };
 
 LU_TYPE_INIT_FINI(echo, &echo_thread_key, &echo_session_key);
@@ -787,6 +775,8 @@ static struct lu_device *echo_device_free(const struct lu_env *env,
 	cl_device_fini(&ed->ed_cl);
 	kfree(ed);
 
+	cl_env_cache_purge(~0);
+
 	return NULL;
 }
 
diff --git a/drivers/staging/lustre/lustre/osc/osc_cache.c b/drivers/staging/lustre/lustre/osc/osc_cache.c
index b6459579b6a4..cbbe85ecf4be 100644
--- a/drivers/staging/lustre/lustre/osc/osc_cache.c
+++ b/drivers/staging/lustre/lustre/osc/osc_cache.c
@@ -977,7 +977,6 @@ static int osc_extent_wait(const struct lu_env *env, struct osc_extent *ext,
 static int osc_extent_truncate(struct osc_extent *ext, pgoff_t trunc_index,
 			       bool partial)
 {
-	struct cl_env_nest nest;
 	struct lu_env *env;
 	struct cl_io *io;
 	struct osc_object *obj = ext->oe_obj;
@@ -990,6 +989,7 @@ static int osc_extent_truncate(struct osc_extent *ext, pgoff_t trunc_index,
 	int grants = 0;
 	int nr_pages = 0;
 	int rc = 0;
+	int refcheck;
 
 	LASSERT(sanity_check(ext) == 0);
 	EASSERT(ext->oe_state == OES_TRUNC, ext);
@@ -999,7 +999,7 @@ static int osc_extent_truncate(struct osc_extent *ext, pgoff_t trunc_index,
 	 * We can't use that env from osc_cache_truncate_start() because
 	 * it's from lov_io_sub and not fully initialized.
 	 */
-	env = cl_env_nested_get(&nest);
+	env = cl_env_get(&refcheck);
 	io  = &osc_env_info(env)->oti_io;
 	io->ci_obj = cl_object_top(osc2cl(obj));
 	rc = cl_io_init(env, io, CIT_MISC, io->ci_obj);
@@ -1085,7 +1085,7 @@ static int osc_extent_truncate(struct osc_extent *ext, pgoff_t trunc_index,
 
 out:
 	cl_io_fini(env, io);
-	cl_env_nested_put(&nest, env);
+	cl_env_put(env, &refcheck);
 	return rc;
 }
 
diff --git a/drivers/staging/lustre/lustre/osc/osc_lock.c b/drivers/staging/lustre/lustre/osc/osc_lock.c
index 45d5e6d6325b..e337e8706c7e 100644
--- a/drivers/staging/lustre/lustre/osc/osc_lock.c
+++ b/drivers/staging/lustre/lustre/osc/osc_lock.c
@@ -294,10 +294,10 @@ static int osc_lock_upcall(void *cookie, struct lustre_handle *lockh,
 	struct osc_lock *oscl = cookie;
 	struct cl_lock_slice *slice = &oscl->ols_cl;
 	struct lu_env *env;
-	struct cl_env_nest nest;
 	int rc;
+	int refcheck;
 
-	env = cl_env_nested_get(&nest);
+	env = cl_env_get(&refcheck);
 	/* should never happen, similar to osc_ldlm_blocking_ast(). */
 	LASSERT(!IS_ERR(env));
 
@@ -336,7 +336,7 @@ static int osc_lock_upcall(void *cookie, struct lustre_handle *lockh,
 
 	if (oscl->ols_owner)
 		cl_sync_io_note(env, oscl->ols_owner, rc);
-	cl_env_nested_put(&nest, env);
+	cl_env_put(env, &refcheck);
 
 	return rc;
 }
@@ -347,9 +347,9 @@ static int osc_lock_upcall_agl(void *cookie, struct lustre_handle *lockh,
 	struct osc_object *osc = cookie;
 	struct ldlm_lock *dlmlock;
 	struct lu_env *env;
-	struct cl_env_nest nest;
+	int refcheck;
 
-	env = cl_env_nested_get(&nest);
+	env = cl_env_get(&refcheck);
 	LASSERT(!IS_ERR(env));
 
 	if (errcode == ELDLM_LOCK_MATCHED) {
@@ -374,7 +374,7 @@ static int osc_lock_upcall_agl(void *cookie, struct lustre_handle *lockh,
 
 out:
 	cl_object_put(env, osc2cl(osc));
-	cl_env_nested_put(&nest, env);
+	cl_env_put(env, &refcheck);
 	return ldlm_error2errno(errcode);
 }
 
@@ -382,11 +382,11 @@ static int osc_lock_flush(struct osc_object *obj, pgoff_t start, pgoff_t end,
 			  enum cl_lock_mode mode, int discard)
 {
 	struct lu_env *env;
-	struct cl_env_nest nest;
+	int refcheck;
 	int rc = 0;
 	int rc2 = 0;
 
-	env = cl_env_nested_get(&nest);
+	env = cl_env_get(&refcheck);
 	if (IS_ERR(env))
 		return PTR_ERR(env);
 
@@ -404,7 +404,7 @@ static int osc_lock_flush(struct osc_object *obj, pgoff_t start, pgoff_t end,
 	if (rc == 0 && rc2 < 0)
 		rc = rc2;
 
-	cl_env_nested_put(&nest, env);
+	cl_env_put(env, &refcheck);
 	return rc;
 }
 
@@ -536,7 +536,7 @@ static int osc_ldlm_blocking_ast(struct ldlm_lock *dlmlock,
 	}
 	case LDLM_CB_CANCELING: {
 		struct lu_env *env;
-		struct cl_env_nest nest;
+		int refcheck;
 
 		/*
 		 * This can be called in the context of outer IO, e.g.,
@@ -549,14 +549,14 @@ static int osc_ldlm_blocking_ast(struct ldlm_lock *dlmlock,
 		 * new environment has to be created to not corrupt outer
 		 * context.
 		 */
-		env = cl_env_nested_get(&nest);
+		env = cl_env_get(&refcheck);
 		if (IS_ERR(env)) {
 			result = PTR_ERR(env);
 			break;
 		}
 
 		result = osc_dlm_blocking_ast0(env, dlmlock, data, flag);
-		cl_env_nested_put(&nest, env);
+		cl_env_put(env, &refcheck);
 		break;
 		}
 	default:
@@ -568,61 +568,61 @@ static int osc_ldlm_blocking_ast(struct ldlm_lock *dlmlock,
 static int osc_ldlm_glimpse_ast(struct ldlm_lock *dlmlock, void *data)
 {
 	struct ptlrpc_request *req = data;
-	struct cl_env_nest nest;
 	struct lu_env *env;
 	struct ost_lvb *lvb;
 	struct req_capsule *cap;
+	struct cl_object *obj = NULL;
 	int result;
+	int refcheck;
 
 	LASSERT(lustre_msg_get_opc(req->rq_reqmsg) == LDLM_GL_CALLBACK);
 
-	env = cl_env_nested_get(&nest);
-	if (!IS_ERR(env)) {
-		struct cl_object *obj = NULL;
+	env = cl_env_get(&refcheck);
+	if (IS_ERR(env)) {
+		result = PTR_ERR(env);
+		goto out;
+	}
 
-		lock_res_and_lock(dlmlock);
-		if (dlmlock->l_ast_data) {
-			obj = osc2cl(dlmlock->l_ast_data);
-			cl_object_get(obj);
-		}
-		unlock_res_and_lock(dlmlock);
+	lock_res_and_lock(dlmlock);
+	if (dlmlock->l_ast_data) {
+		obj = osc2cl(dlmlock->l_ast_data);
+		cl_object_get(obj);
+	}
+	unlock_res_and_lock(dlmlock);
 
-		if (obj) {
-			/* Do not grab the mutex of cl_lock for glimpse.
-			 * See LU-1274 for details.
-			 * BTW, it's okay for cl_lock to be cancelled during
-			 * this period because server can handle this race.
-			 * See ldlm_server_glimpse_ast() for details.
-			 * cl_lock_mutex_get(env, lock);
-			 */
-			cap = &req->rq_pill;
-			req_capsule_extend(cap, &RQF_LDLM_GL_CALLBACK);
-			req_capsule_set_size(cap, &RMF_DLM_LVB, RCL_SERVER,
-					     sizeof(*lvb));
-			result = req_capsule_server_pack(cap);
-			if (result == 0) {
-				lvb = req_capsule_server_get(cap, &RMF_DLM_LVB);
-				result = cl_object_glimpse(env, obj, lvb);
-			}
-			if (!exp_connect_lvb_type(req->rq_export))
-				req_capsule_shrink(&req->rq_pill,
-						   &RMF_DLM_LVB,
-						   sizeof(struct ost_lvb_v1),
-						   RCL_SERVER);
-			cl_object_put(env, obj);
-		} else {
-			/*
-			 * These errors are normal races, so we don't want to
-			 * fill the console with messages by calling
-			 * ptlrpc_error()
-			 */
-			lustre_pack_reply(req, 1, NULL, NULL);
-			result = -ELDLM_NO_LOCK_DATA;
+	if (obj) {
+		/* Do not grab the mutex of cl_lock for glimpse.
+		 * See LU-1274 for details.
+		 * BTW, it's okay for cl_lock to be cancelled during
+		 * this period because server can handle this race.
+		 * See ldlm_server_glimpse_ast() for details.
+		 * cl_lock_mutex_get(env, lock);
+		 */
+		cap = &req->rq_pill;
+		req_capsule_extend(cap, &RQF_LDLM_GL_CALLBACK);
+		req_capsule_set_size(cap, &RMF_DLM_LVB, RCL_SERVER,
+				     sizeof(*lvb));
+		result = req_capsule_server_pack(cap);
+		if (result == 0) {
+			lvb = req_capsule_server_get(cap, &RMF_DLM_LVB);
+			result = cl_object_glimpse(env, obj, lvb);
 		}
-		cl_env_nested_put(&nest, env);
+		if (!exp_connect_lvb_type(req->rq_export))
+		req_capsule_shrink(&req->rq_pill, &RMF_DLM_LVB,
+				   sizeof(struct ost_lvb_v1), RCL_SERVER);
+		cl_object_put(env, obj);
 	} else {
-		result = PTR_ERR(env);
+		/*
+		 * These errors are normal races, so we don't want to
+		 * fill the console with messages by calling
+		 * ptlrpc_error()
+		 */
+		lustre_pack_reply(req, 1, NULL, NULL);
+		result = -ELDLM_NO_LOCK_DATA;
 	}
+	cl_env_put(env, &refcheck);
+
+out:
 	req->rq_status = result;
 	return result;
 }
@@ -677,12 +677,12 @@ static unsigned long osc_lock_weight(const struct lu_env *env,
  */
 unsigned long osc_ldlm_weigh_ast(struct ldlm_lock *dlmlock)
 {
-	struct cl_env_nest       nest;
 	struct lu_env           *env;
 	struct osc_object	*obj;
 	struct osc_lock		*oscl;
 	unsigned long            weight;
 	bool			 found = false;
+	int refcheck;
 
 	might_sleep();
 	/*
@@ -692,7 +692,7 @@ unsigned long osc_ldlm_weigh_ast(struct ldlm_lock *dlmlock)
 	 * the upper context because cl_lock_put don't modify environment
 	 * variables. But just in case ..
 	 */
-	env = cl_env_nested_get(&nest);
+	env = cl_env_get(&refcheck);
 	if (IS_ERR(env))
 		/* Mostly because lack of memory, do not eliminate this lock */
 		return 1;
@@ -722,7 +722,7 @@ unsigned long osc_ldlm_weigh_ast(struct ldlm_lock *dlmlock)
 	weight = osc_lock_weight(env, obj, &dlmlock->l_policy_data.l_extent);
 
 out:
-	cl_env_nested_put(&nest, env);
+	cl_env_put(env, &refcheck);
 	return weight;
 }
 
diff --git a/drivers/staging/lustre/lustre/osc/osc_page.c b/drivers/staging/lustre/lustre/osc/osc_page.c
index 2fb0e53c2de2..93248d1fb314 100644
--- a/drivers/staging/lustre/lustre/osc/osc_page.c
+++ b/drivers/staging/lustre/lustre/osc/osc_page.c
@@ -644,15 +644,15 @@ long osc_lru_shrink(const struct lu_env *env, struct client_obd *cli,
 
 long osc_lru_reclaim(struct client_obd *cli)
 {
-	struct cl_env_nest nest;
 	struct lu_env *env;
 	struct cl_client_cache *cache = cli->cl_cache;
 	int max_scans;
+	int refcheck;
 	long rc = 0;
 
 	LASSERT(cache);
 
-	env = cl_env_nested_get(&nest);
+	env = cl_env_get(&refcheck);
 	if (IS_ERR(env))
 		return 0;
 
@@ -704,7 +704,7 @@ long osc_lru_reclaim(struct client_obd *cli)
 	spin_unlock(&cache->ccc_lru_lock);
 
 out:
-	cl_env_nested_put(&nest, env);
+	cl_env_put(env, &refcheck);
 	CDEBUG(D_CACHE, "%s: cli %p freed %ld pages.\n",
 	       cli->cl_import->imp_obd->obd_name, cli, rc);
 	return rc;