X-Git-Url: https://gerrit.opnfv.org/gerrit/gitweb?a=blobdiff_plain;f=kernel%2Fdrivers%2Fstaging%2Flustre%2Flustre%2Fldlm%2Fldlm_lock.c;fp=kernel%2Fdrivers%2Fstaging%2Flustre%2Flustre%2Fldlm%2Fldlm_lock.c;h=84b111eb48fad5060a0b32565d46662de3170cc8;hb=9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00;hp=0000000000000000000000000000000000000000;hpb=98260f3884f4a202f9ca5eabed40b1354c489b29;p=kvmfornfv.git

diff --git a/kernel/drivers/staging/lustre/lustre/ldlm/ldlm_lock.c b/kernel/drivers/staging/lustre/lustre/ldlm/ldlm_lock.c
new file mode 100644
index 000000000..84b111eb4
--- /dev/null
+++ b/kernel/drivers/staging/lustre/lustre/ldlm/ldlm_lock.c
@@ -0,0 +1,2322 @@
+/*
+ * 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) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Use is subject to license terms.
+ *
+ * Copyright (c) 2010, 2012, Intel Corporation.
+ */
+/*
+ * This file is part of Lustre, http://www.lustre.org/
+ * Lustre is a trademark of Sun Microsystems, Inc.
+ *
+ * lustre/ldlm/ldlm_lock.c
+ *
+ * Author: Peter Braam <braam@clusterfs.com>
+ * Author: Phil Schwan <phil@clusterfs.com>
+ */
+
+#define DEBUG_SUBSYSTEM S_LDLM
+
+#include "../../include/linux/libcfs/libcfs.h"
+#include "../include/lustre_intent.h"
+#include "../include/obd_class.h"
+#include "ldlm_internal.h"
+
+/* lock types */
+char *ldlm_lockname[] = {
+	[0]		= "--",
+	[LCK_EX]	= "EX",
+	[LCK_PW]	= "PW",
+	[LCK_PR]	= "PR",
+	[LCK_CW]	= "CW",
+	[LCK_CR]	= "CR",
+	[LCK_NL]	= "NL",
+	[LCK_GROUP]	= "GROUP",
+	[LCK_COS]	= "COS",
+};
+EXPORT_SYMBOL(ldlm_lockname);
+
+char *ldlm_typename[] = {
+	[LDLM_PLAIN]	= "PLN",
+	[LDLM_EXTENT]	= "EXT",
+	[LDLM_FLOCK]	= "FLK",
+	[LDLM_IBITS]	= "IBT",
+};
+EXPORT_SYMBOL(ldlm_typename);
+
+static ldlm_policy_wire_to_local_t ldlm_policy_wire18_to_local[] = {
+	[LDLM_PLAIN - LDLM_MIN_TYPE]	= ldlm_plain_policy_wire_to_local,
+	[LDLM_EXTENT - LDLM_MIN_TYPE]	= ldlm_extent_policy_wire_to_local,
+	[LDLM_FLOCK - LDLM_MIN_TYPE]	= ldlm_flock_policy_wire18_to_local,
+	[LDLM_IBITS - LDLM_MIN_TYPE]	= ldlm_ibits_policy_wire_to_local,
+};
+
+static ldlm_policy_wire_to_local_t ldlm_policy_wire21_to_local[] = {
+	[LDLM_PLAIN - LDLM_MIN_TYPE]	= ldlm_plain_policy_wire_to_local,
+	[LDLM_EXTENT - LDLM_MIN_TYPE]	= ldlm_extent_policy_wire_to_local,
+	[LDLM_FLOCK - LDLM_MIN_TYPE]	= ldlm_flock_policy_wire21_to_local,
+	[LDLM_IBITS - LDLM_MIN_TYPE]	= ldlm_ibits_policy_wire_to_local,
+};
+
+static ldlm_policy_local_to_wire_t ldlm_policy_local_to_wire[] = {
+	[LDLM_PLAIN - LDLM_MIN_TYPE]	= ldlm_plain_policy_local_to_wire,
+	[LDLM_EXTENT - LDLM_MIN_TYPE]	= ldlm_extent_policy_local_to_wire,
+	[LDLM_FLOCK - LDLM_MIN_TYPE]	= ldlm_flock_policy_local_to_wire,
+	[LDLM_IBITS - LDLM_MIN_TYPE]	= ldlm_ibits_policy_local_to_wire,
+};
+
+/**
+ * Converts lock policy from local format to on the wire lock_desc format
+ */
+void ldlm_convert_policy_to_wire(ldlm_type_t type,
+				 const ldlm_policy_data_t *lpolicy,
+				 ldlm_wire_policy_data_t *wpolicy)
+{
+	ldlm_policy_local_to_wire_t convert;
+
+	convert = ldlm_policy_local_to_wire[type - LDLM_MIN_TYPE];
+
+	convert(lpolicy, wpolicy);
+}
+
+/**
+ * Converts lock policy from on the wire lock_desc format to local format
+ */
+void ldlm_convert_policy_to_local(struct obd_export *exp, ldlm_type_t type,
+				  const ldlm_wire_policy_data_t *wpolicy,
+				  ldlm_policy_data_t *lpolicy)
+{
+	ldlm_policy_wire_to_local_t convert;
+	int new_client;
+
+	/** some badness for 2.0.0 clients, but 2.0.0 isn't supported */
+	new_client = (exp_connect_flags(exp) & OBD_CONNECT_FULL20) != 0;
+	if (new_client)
+		convert = ldlm_policy_wire21_to_local[type - LDLM_MIN_TYPE];
+	else
+		convert = ldlm_policy_wire18_to_local[type - LDLM_MIN_TYPE];
+
+	convert(wpolicy, lpolicy);
+}
+
+char *ldlm_it2str(int it)
+{
+	switch (it) {
+	case IT_OPEN:
+		return "open";
+	case IT_CREAT:
+		return "creat";
+	case (IT_OPEN | IT_CREAT):
+		return "open|creat";
+	case IT_READDIR:
+		return "readdir";
+	case IT_GETATTR:
+		return "getattr";
+	case IT_LOOKUP:
+		return "lookup";
+	case IT_UNLINK:
+		return "unlink";
+	case IT_GETXATTR:
+		return "getxattr";
+	case IT_LAYOUT:
+		return "layout";
+	default:
+		CERROR("Unknown intent %d\n", it);
+		return "UNKNOWN";
+	}
+}
+EXPORT_SYMBOL(ldlm_it2str);
+
+
+void ldlm_register_intent(struct ldlm_namespace *ns, ldlm_res_policy arg)
+{
+	ns->ns_policy = arg;
+}
+EXPORT_SYMBOL(ldlm_register_intent);
+
+/*
+ * REFCOUNTED LOCK OBJECTS
+ */
+
+
+/**
+ * Get a reference on a lock.
+ *
+ * Lock refcounts, during creation:
+ *   - one special one for allocation, dec'd only once in destroy
+ *   - one for being a lock that's in-use
+ *   - one for the addref associated with a new lock
+ */
+struct ldlm_lock *ldlm_lock_get(struct ldlm_lock *lock)
+{
+	atomic_inc(&lock->l_refc);
+	return lock;
+}
+EXPORT_SYMBOL(ldlm_lock_get);
+
+/**
+ * Release lock reference.
+ *
+ * Also frees the lock if it was last reference.
+ */
+void ldlm_lock_put(struct ldlm_lock *lock)
+{
+	LASSERT(lock->l_resource != LP_POISON);
+	LASSERT(atomic_read(&lock->l_refc) > 0);
+	if (atomic_dec_and_test(&lock->l_refc)) {
+		struct ldlm_resource *res;
+
+		LDLM_DEBUG(lock,
+			   "final lock_put on destroyed lock, freeing it.");
+
+		res = lock->l_resource;
+		LASSERT(lock->l_flags & LDLM_FL_DESTROYED);
+		LASSERT(list_empty(&lock->l_res_link));
+		LASSERT(list_empty(&lock->l_pending_chain));
+
+		lprocfs_counter_decr(ldlm_res_to_ns(res)->ns_stats,
+				     LDLM_NSS_LOCKS);
+		lu_ref_del(&res->lr_reference, "lock", lock);
+		ldlm_resource_putref(res);
+		lock->l_resource = NULL;
+		if (lock->l_export) {
+			class_export_lock_put(lock->l_export, lock);
+			lock->l_export = NULL;
+		}
+
+		if (lock->l_lvb_data != NULL)
+			OBD_FREE(lock->l_lvb_data, lock->l_lvb_len);
+
+		ldlm_interval_free(ldlm_interval_detach(lock));
+		lu_ref_fini(&lock->l_reference);
+		OBD_FREE_RCU(lock, sizeof(*lock), &lock->l_handle);
+	}
+}
+EXPORT_SYMBOL(ldlm_lock_put);
+
+/**
+ * Removes LDLM lock \a lock from LRU. Assumes LRU is already locked.
+ */
+int ldlm_lock_remove_from_lru_nolock(struct ldlm_lock *lock)
+{
+	int rc = 0;
+
+	if (!list_empty(&lock->l_lru)) {
+		struct ldlm_namespace *ns = ldlm_lock_to_ns(lock);
+
+		LASSERT(lock->l_resource->lr_type != LDLM_FLOCK);
+		list_del_init(&lock->l_lru);
+		LASSERT(ns->ns_nr_unused > 0);
+		ns->ns_nr_unused--;
+		rc = 1;
+	}
+	return rc;
+}
+
+/**
+ * Removes LDLM lock \a lock from LRU. Obtains the LRU lock first.
+ */
+int ldlm_lock_remove_from_lru(struct ldlm_lock *lock)
+{
+	struct ldlm_namespace *ns = ldlm_lock_to_ns(lock);
+	int rc;
+
+	if (lock->l_flags & LDLM_FL_NS_SRV) {
+		LASSERT(list_empty(&lock->l_lru));
+		return 0;
+	}
+
+	spin_lock(&ns->ns_lock);
+	rc = ldlm_lock_remove_from_lru_nolock(lock);
+	spin_unlock(&ns->ns_lock);
+	return rc;
+}
+
+/**
+ * Adds LDLM lock \a lock to namespace LRU. Assumes LRU is already locked.
+ */
+void ldlm_lock_add_to_lru_nolock(struct ldlm_lock *lock)
+{
+	struct ldlm_namespace *ns = ldlm_lock_to_ns(lock);
+
+	lock->l_last_used = cfs_time_current();
+	LASSERT(list_empty(&lock->l_lru));
+	LASSERT(lock->l_resource->lr_type != LDLM_FLOCK);
+	list_add_tail(&lock->l_lru, &ns->ns_unused_list);
+	if (lock->l_flags & LDLM_FL_SKIPPED)
+		lock->l_flags &= ~LDLM_FL_SKIPPED;
+	LASSERT(ns->ns_nr_unused >= 0);
+	ns->ns_nr_unused++;
+}
+
+/**
+ * Adds LDLM lock \a lock to namespace LRU. Obtains necessary LRU locks
+ * first.
+ */
+void ldlm_lock_add_to_lru(struct ldlm_lock *lock)
+{
+	struct ldlm_namespace *ns = ldlm_lock_to_ns(lock);
+
+	spin_lock(&ns->ns_lock);
+	ldlm_lock_add_to_lru_nolock(lock);
+	spin_unlock(&ns->ns_lock);
+}
+
+/**
+ * Moves LDLM lock \a lock that is already in namespace LRU to the tail of
+ * the LRU. Performs necessary LRU locking
+ */
+void ldlm_lock_touch_in_lru(struct ldlm_lock *lock)
+{
+	struct ldlm_namespace *ns = ldlm_lock_to_ns(lock);
+
+	if (lock->l_flags & LDLM_FL_NS_SRV) {
+		LASSERT(list_empty(&lock->l_lru));
+		return;
+	}
+
+	spin_lock(&ns->ns_lock);
+	if (!list_empty(&lock->l_lru)) {
+		ldlm_lock_remove_from_lru_nolock(lock);
+		ldlm_lock_add_to_lru_nolock(lock);
+	}
+	spin_unlock(&ns->ns_lock);
+}
+
+/**
+ * Helper to destroy a locked lock.
+ *
+ * Used by ldlm_lock_destroy and ldlm_lock_destroy_nolock
+ * Must be called with l_lock and lr_lock held.
+ *
+ * Does not actually free the lock data, but rather marks the lock as
+ * destroyed by setting l_destroyed field in the lock to 1.  Destroys a
+ * handle->lock association too, so that the lock can no longer be found
+ * and removes the lock from LRU list.  Actual lock freeing occurs when
+ * last lock reference goes away.
+ *
+ * Original comment (of some historical value):
+ * This used to have a 'strict' flag, which recovery would use to mark an
+ * in-use lock as needing-to-die.  Lest I am ever tempted to put it back, I
+ * shall explain why it's gone: with the new hash table scheme, once you call
+ * ldlm_lock_destroy, you can never drop your final references on this lock.
+ * Because it's not in the hash table anymore.  -phil
+ */
+int ldlm_lock_destroy_internal(struct ldlm_lock *lock)
+{
+	if (lock->l_readers || lock->l_writers) {
+		LDLM_ERROR(lock, "lock still has references");
+		LBUG();
+	}
+
+	if (!list_empty(&lock->l_res_link)) {
+		LDLM_ERROR(lock, "lock still on resource");
+		LBUG();
+	}
+
+	if (lock->l_flags & LDLM_FL_DESTROYED) {
+		LASSERT(list_empty(&lock->l_lru));
+		return 0;
+	}
+	lock->l_flags |= LDLM_FL_DESTROYED;
+
+	if (lock->l_export && lock->l_export->exp_lock_hash) {
+		/* NB: it's safe to call cfs_hash_del() even lock isn't
+		 * in exp_lock_hash. */
+		/* In the function below, .hs_keycmp resolves to
+		 * ldlm_export_lock_keycmp() */
+		/* coverity[overrun-buffer-val] */
+		cfs_hash_del(lock->l_export->exp_lock_hash,
+			     &lock->l_remote_handle, &lock->l_exp_hash);
+	}
+
+	ldlm_lock_remove_from_lru(lock);
+	class_handle_unhash(&lock->l_handle);
+
+#if 0
+	/* Wake anyone waiting for this lock */
+	/* FIXME: I should probably add yet another flag, instead of using
+	 * l_export to only call this on clients */
+	if (lock->l_export)
+		class_export_put(lock->l_export);
+	lock->l_export = NULL;
+	if (lock->l_export && lock->l_completion_ast)
+		lock->l_completion_ast(lock, 0);
+#endif
+	return 1;
+}
+
+/**
+ * Destroys a LDLM lock \a lock. Performs necessary locking first.
+ */
+void ldlm_lock_destroy(struct ldlm_lock *lock)
+{
+	int first;
+
+	lock_res_and_lock(lock);
+	first = ldlm_lock_destroy_internal(lock);
+	unlock_res_and_lock(lock);
+
+	/* drop reference from hashtable only for first destroy */
+	if (first) {
+		lu_ref_del(&lock->l_reference, "hash", lock);
+		LDLM_LOCK_RELEASE(lock);
+	}
+}
+
+/**
+ * Destroys a LDLM lock \a lock that is already locked.
+ */
+void ldlm_lock_destroy_nolock(struct ldlm_lock *lock)
+{
+	int first;
+
+	first = ldlm_lock_destroy_internal(lock);
+	/* drop reference from hashtable only for first destroy */
+	if (first) {
+		lu_ref_del(&lock->l_reference, "hash", lock);
+		LDLM_LOCK_RELEASE(lock);
+	}
+}
+
+/* this is called by portals_handle2object with the handle lock taken */
+static void lock_handle_addref(void *lock)
+{
+	LDLM_LOCK_GET((struct ldlm_lock *)lock);
+}
+
+static void lock_handle_free(void *lock, int size)
+{
+	LASSERT(size == sizeof(struct ldlm_lock));
+	OBD_SLAB_FREE(lock, ldlm_lock_slab, size);
+}
+
+struct portals_handle_ops lock_handle_ops = {
+	.hop_addref = lock_handle_addref,
+	.hop_free   = lock_handle_free,
+};
+
+/**
+ *
+ * Allocate and initialize new lock structure.
+ *
+ * usage: pass in a resource on which you have done ldlm_resource_get
+ *	new lock will take over the refcount.
+ * returns: lock with refcount 2 - one for current caller and one for remote
+ */
+static struct ldlm_lock *ldlm_lock_new(struct ldlm_resource *resource)
+{
+	struct ldlm_lock *lock;
+
+	if (resource == NULL)
+		LBUG();
+
+	OBD_SLAB_ALLOC_PTR_GFP(lock, ldlm_lock_slab, GFP_NOFS);
+	if (lock == NULL)
+		return NULL;
+
+	spin_lock_init(&lock->l_lock);
+	lock->l_resource = resource;
+	lu_ref_add(&resource->lr_reference, "lock", lock);
+
+	atomic_set(&lock->l_refc, 2);
+	INIT_LIST_HEAD(&lock->l_res_link);
+	INIT_LIST_HEAD(&lock->l_lru);
+	INIT_LIST_HEAD(&lock->l_pending_chain);
+	INIT_LIST_HEAD(&lock->l_bl_ast);
+	INIT_LIST_HEAD(&lock->l_cp_ast);
+	INIT_LIST_HEAD(&lock->l_rk_ast);
+	init_waitqueue_head(&lock->l_waitq);
+	lock->l_blocking_lock = NULL;
+	INIT_LIST_HEAD(&lock->l_sl_mode);
+	INIT_LIST_HEAD(&lock->l_sl_policy);
+	INIT_HLIST_NODE(&lock->l_exp_hash);
+	INIT_HLIST_NODE(&lock->l_exp_flock_hash);
+
+	lprocfs_counter_incr(ldlm_res_to_ns(resource)->ns_stats,
+			     LDLM_NSS_LOCKS);
+	INIT_LIST_HEAD(&lock->l_handle.h_link);
+	class_handle_hash(&lock->l_handle, &lock_handle_ops);
+
+	lu_ref_init(&lock->l_reference);
+	lu_ref_add(&lock->l_reference, "hash", lock);
+	lock->l_callback_timeout = 0;
+
+#if LUSTRE_TRACKS_LOCK_EXP_REFS
+	INIT_LIST_HEAD(&lock->l_exp_refs_link);
+	lock->l_exp_refs_nr = 0;
+	lock->l_exp_refs_target = NULL;
+#endif
+	INIT_LIST_HEAD(&lock->l_exp_list);
+
+	return lock;
+}
+
+/**
+ * Moves LDLM lock \a lock to another resource.
+ * This is used on client when server returns some other lock than requested
+ * (typically as a result of intent operation)
+ */
+int ldlm_lock_change_resource(struct ldlm_namespace *ns, struct ldlm_lock *lock,
+			      const struct ldlm_res_id *new_resid)
+{
+	struct ldlm_resource *oldres = lock->l_resource;
+	struct ldlm_resource *newres;
+	int type;
+
+	LASSERT(ns_is_client(ns));
+
+	lock_res_and_lock(lock);
+	if (memcmp(new_resid, &lock->l_resource->lr_name,
+		   sizeof(lock->l_resource->lr_name)) == 0) {
+		/* Nothing to do */
+		unlock_res_and_lock(lock);
+		return 0;
+	}
+
+	LASSERT(new_resid->name[0] != 0);
+
+	/* This function assumes that the lock isn't on any lists */
+	LASSERT(list_empty(&lock->l_res_link));
+
+	type = oldres->lr_type;
+	unlock_res_and_lock(lock);
+
+	newres = ldlm_resource_get(ns, NULL, new_resid, type, 1);
+	if (newres == NULL)
+		return -ENOMEM;
+
+	lu_ref_add(&newres->lr_reference, "lock", lock);
+	/*
+	 * To flip the lock from the old to the new resource, lock, oldres and
+	 * newres have to be locked. Resource spin-locks are nested within
+	 * lock->l_lock, and are taken in the memory address order to avoid
+	 * dead-locks.
+	 */
+	spin_lock(&lock->l_lock);
+	oldres = lock->l_resource;
+	if (oldres < newres) {
+		lock_res(oldres);
+		lock_res_nested(newres, LRT_NEW);
+	} else {
+		lock_res(newres);
+		lock_res_nested(oldres, LRT_NEW);
+	}
+	LASSERT(memcmp(new_resid, &oldres->lr_name,
+		       sizeof(oldres->lr_name)) != 0);
+	lock->l_resource = newres;
+	unlock_res(oldres);
+	unlock_res_and_lock(lock);
+
+	/* ...and the flowers are still standing! */
+	lu_ref_del(&oldres->lr_reference, "lock", lock);
+	ldlm_resource_putref(oldres);
+
+	return 0;
+}
+EXPORT_SYMBOL(ldlm_lock_change_resource);
+
+/** \defgroup ldlm_handles LDLM HANDLES
+ * Ways to get hold of locks without any addresses.
+ * @{
+ */
+
+/**
+ * Fills in handle for LDLM lock \a lock into supplied \a lockh
+ * Does not take any references.
+ */
+void ldlm_lock2handle(const struct ldlm_lock *lock, struct lustre_handle *lockh)
+{
+	lockh->cookie = lock->l_handle.h_cookie;
+}
+EXPORT_SYMBOL(ldlm_lock2handle);
+
+/**
+ * Obtain a lock reference by handle.
+ *
+ * if \a flags: atomically get the lock and set the flags.
+ *	      Return NULL if flag already set
+ */
+struct ldlm_lock *__ldlm_handle2lock(const struct lustre_handle *handle,
+				     __u64 flags)
+{
+	struct ldlm_lock *lock;
+
+	LASSERT(handle);
+
+	lock = class_handle2object(handle->cookie);
+	if (lock == NULL)
+		return NULL;
+
+	/* It's unlikely but possible that someone marked the lock as
+	 * destroyed after we did handle2object on it */
+	if (flags == 0 && ((lock->l_flags & LDLM_FL_DESTROYED) == 0)) {
+		lu_ref_add(&lock->l_reference, "handle", current);
+		return lock;
+	}
+
+	lock_res_and_lock(lock);
+
+	LASSERT(lock->l_resource != NULL);
+
+	lu_ref_add_atomic(&lock->l_reference, "handle", current);
+	if (unlikely(lock->l_flags & LDLM_FL_DESTROYED)) {
+		unlock_res_and_lock(lock);
+		CDEBUG(D_INFO, "lock already destroyed: lock %p\n", lock);
+		LDLM_LOCK_PUT(lock);
+		return NULL;
+	}
+
+	if (flags && (lock->l_flags & flags)) {
+		unlock_res_and_lock(lock);
+		LDLM_LOCK_PUT(lock);
+		return NULL;
+	}
+
+	if (flags)
+		lock->l_flags |= flags;
+
+	unlock_res_and_lock(lock);
+	return lock;
+}
+EXPORT_SYMBOL(__ldlm_handle2lock);
+/** @} ldlm_handles */
+
+/**
+ * Fill in "on the wire" representation for given LDLM lock into supplied
+ * lock descriptor \a desc structure.
+ */
+void ldlm_lock2desc(struct ldlm_lock *lock, struct ldlm_lock_desc *desc)
+{
+	ldlm_res2desc(lock->l_resource, &desc->l_resource);
+	desc->l_req_mode = lock->l_req_mode;
+	desc->l_granted_mode = lock->l_granted_mode;
+	ldlm_convert_policy_to_wire(lock->l_resource->lr_type,
+				    &lock->l_policy_data,
+				    &desc->l_policy_data);
+}
+EXPORT_SYMBOL(ldlm_lock2desc);
+
+/**
+ * Add a lock to list of conflicting locks to send AST to.
+ *
+ * Only add if we have not sent a blocking AST to the lock yet.
+ */
+void ldlm_add_bl_work_item(struct ldlm_lock *lock, struct ldlm_lock *new,
+			   struct list_head *work_list)
+{
+	if ((lock->l_flags & LDLM_FL_AST_SENT) == 0) {
+		LDLM_DEBUG(lock, "lock incompatible; sending blocking AST.");
+		lock->l_flags |= LDLM_FL_AST_SENT;
+		/* If the enqueuing client said so, tell the AST recipient to
+		 * discard dirty data, rather than writing back. */
+		if (new->l_flags & LDLM_FL_AST_DISCARD_DATA)
+			lock->l_flags |= LDLM_FL_DISCARD_DATA;
+		LASSERT(list_empty(&lock->l_bl_ast));
+		list_add(&lock->l_bl_ast, work_list);
+		LDLM_LOCK_GET(lock);
+		LASSERT(lock->l_blocking_lock == NULL);
+		lock->l_blocking_lock = LDLM_LOCK_GET(new);
+	}
+}
+
+/**
+ * Add a lock to list of just granted locks to send completion AST to.
+ */
+void ldlm_add_cp_work_item(struct ldlm_lock *lock, struct list_head *work_list)
+{
+	if ((lock->l_flags & LDLM_FL_CP_REQD) == 0) {
+		lock->l_flags |= LDLM_FL_CP_REQD;
+		LDLM_DEBUG(lock, "lock granted; sending completion AST.");
+		LASSERT(list_empty(&lock->l_cp_ast));
+		list_add(&lock->l_cp_ast, work_list);
+		LDLM_LOCK_GET(lock);
+	}
+}
+
+/**
+ * Aggregator function to add AST work items into a list. Determines
+ * what sort of an AST work needs to be done and calls the proper
+ * adding function.
+ * Must be called with lr_lock held.
+ */
+void ldlm_add_ast_work_item(struct ldlm_lock *lock, struct ldlm_lock *new,
+			    struct list_head *work_list)
+{
+	check_res_locked(lock->l_resource);
+	if (new)
+		ldlm_add_bl_work_item(lock, new, work_list);
+	else
+		ldlm_add_cp_work_item(lock, work_list);
+}
+
+/**
+ * Add specified reader/writer reference to LDLM lock with handle \a lockh.
+ * r/w reference type is determined by \a mode
+ * Calls ldlm_lock_addref_internal.
+ */
+void ldlm_lock_addref(struct lustre_handle *lockh, __u32 mode)
+{
+	struct ldlm_lock *lock;
+
+	lock = ldlm_handle2lock(lockh);
+	LASSERT(lock != NULL);
+	ldlm_lock_addref_internal(lock, mode);
+	LDLM_LOCK_PUT(lock);
+}
+EXPORT_SYMBOL(ldlm_lock_addref);
+
+/**
+ * Helper function.
+ * Add specified reader/writer reference to LDLM lock \a lock.
+ * r/w reference type is determined by \a mode
+ * Removes lock from LRU if it is there.
+ * Assumes the LDLM lock is already locked.
+ */
+void ldlm_lock_addref_internal_nolock(struct ldlm_lock *lock, __u32 mode)
+{
+	ldlm_lock_remove_from_lru(lock);
+	if (mode & (LCK_NL | LCK_CR | LCK_PR)) {
+		lock->l_readers++;
+		lu_ref_add_atomic(&lock->l_reference, "reader", lock);
+	}
+	if (mode & (LCK_EX | LCK_CW | LCK_PW | LCK_GROUP | LCK_COS)) {
+		lock->l_writers++;
+		lu_ref_add_atomic(&lock->l_reference, "writer", lock);
+	}
+	LDLM_LOCK_GET(lock);
+	lu_ref_add_atomic(&lock->l_reference, "user", lock);
+	LDLM_DEBUG(lock, "ldlm_lock_addref(%s)", ldlm_lockname[mode]);
+}
+
+/**
+ * Attempts to add reader/writer reference to a lock with handle \a lockh, and
+ * fails if lock is already LDLM_FL_CBPENDING or destroyed.
+ *
+ * \retval 0 success, lock was addref-ed
+ *
+ * \retval -EAGAIN lock is being canceled.
+ */
+int ldlm_lock_addref_try(struct lustre_handle *lockh, __u32 mode)
+{
+	struct ldlm_lock *lock;
+	int	       result;
+
+	result = -EAGAIN;
+	lock = ldlm_handle2lock(lockh);
+	if (lock != NULL) {
+		lock_res_and_lock(lock);
+		if (lock->l_readers != 0 || lock->l_writers != 0 ||
+		    !(lock->l_flags & LDLM_FL_CBPENDING)) {
+			ldlm_lock_addref_internal_nolock(lock, mode);
+			result = 0;
+		}
+		unlock_res_and_lock(lock);
+		LDLM_LOCK_PUT(lock);
+	}
+	return result;
+}
+EXPORT_SYMBOL(ldlm_lock_addref_try);
+
+/**
+ * Add specified reader/writer reference to LDLM lock \a lock.
+ * Locks LDLM lock and calls ldlm_lock_addref_internal_nolock to do the work.
+ * Only called for local locks.
+ */
+void ldlm_lock_addref_internal(struct ldlm_lock *lock, __u32 mode)
+{
+	lock_res_and_lock(lock);
+	ldlm_lock_addref_internal_nolock(lock, mode);
+	unlock_res_and_lock(lock);
+}
+
+/**
+ * Removes reader/writer reference for LDLM lock \a lock.
+ * Assumes LDLM lock is already locked.
+ * only called in ldlm_flock_destroy and for local locks.
+ * Does NOT add lock to LRU if no r/w references left to accommodate flock locks
+ * that cannot be placed in LRU.
+ */
+void ldlm_lock_decref_internal_nolock(struct ldlm_lock *lock, __u32 mode)
+{
+	LDLM_DEBUG(lock, "ldlm_lock_decref(%s)", ldlm_lockname[mode]);
+	if (mode & (LCK_NL | LCK_CR | LCK_PR)) {
+		LASSERT(lock->l_readers > 0);
+		lu_ref_del(&lock->l_reference, "reader", lock);
+		lock->l_readers--;
+	}
+	if (mode & (LCK_EX | LCK_CW | LCK_PW | LCK_GROUP | LCK_COS)) {
+		LASSERT(lock->l_writers > 0);
+		lu_ref_del(&lock->l_reference, "writer", lock);
+		lock->l_writers--;
+	}
+
+	lu_ref_del(&lock->l_reference, "user", lock);
+	LDLM_LOCK_RELEASE(lock);    /* matches the LDLM_LOCK_GET() in addref */
+}
+
+/**
+ * Removes reader/writer reference for LDLM lock \a lock.
+ * Locks LDLM lock first.
+ * If the lock is determined to be client lock on a client and r/w refcount
+ * drops to zero and the lock is not blocked, the lock is added to LRU lock
+ * on the namespace.
+ * For blocked LDLM locks if r/w count drops to zero, blocking_ast is called.
+ */
+void ldlm_lock_decref_internal(struct ldlm_lock *lock, __u32 mode)
+{
+	struct ldlm_namespace *ns;
+
+	lock_res_and_lock(lock);
+
+	ns = ldlm_lock_to_ns(lock);
+
+	ldlm_lock_decref_internal_nolock(lock, mode);
+
+	if (lock->l_flags & LDLM_FL_LOCAL &&
+	    !lock->l_readers && !lock->l_writers) {
+		/* If this is a local lock on a server namespace and this was
+		 * the last reference, cancel the lock. */
+		CDEBUG(D_INFO, "forcing cancel of local lock\n");
+		lock->l_flags |= LDLM_FL_CBPENDING;
+	}
+
+	if (!lock->l_readers && !lock->l_writers &&
+	    (lock->l_flags & LDLM_FL_CBPENDING)) {
+		/* If we received a blocked AST and this was the last reference,
+		 * run the callback. */
+		if ((lock->l_flags & LDLM_FL_NS_SRV) && lock->l_export)
+			CERROR("FL_CBPENDING set on non-local lock--just a warning\n");
+
+		LDLM_DEBUG(lock, "final decref done on cbpending lock");
+
+		LDLM_LOCK_GET(lock); /* dropped by bl thread */
+		ldlm_lock_remove_from_lru(lock);
+		unlock_res_and_lock(lock);
+
+		if (lock->l_flags & LDLM_FL_FAIL_LOC)
+			OBD_RACE(OBD_FAIL_LDLM_CP_BL_RACE);
+
+		if ((lock->l_flags & LDLM_FL_ATOMIC_CB) ||
+		    ldlm_bl_to_thread_lock(ns, NULL, lock) != 0)
+			ldlm_handle_bl_callback(ns, NULL, lock);
+	} else if (ns_is_client(ns) &&
+		   !lock->l_readers && !lock->l_writers &&
+		   !(lock->l_flags & LDLM_FL_NO_LRU) &&
+		   !(lock->l_flags & LDLM_FL_BL_AST)) {
+
+		LDLM_DEBUG(lock, "add lock into lru list");
+
+		/* If this is a client-side namespace and this was the last
+		 * reference, put it on the LRU. */
+		ldlm_lock_add_to_lru(lock);
+		unlock_res_and_lock(lock);
+
+		if (lock->l_flags & LDLM_FL_FAIL_LOC)
+			OBD_RACE(OBD_FAIL_LDLM_CP_BL_RACE);
+
+		/* Call ldlm_cancel_lru() only if EARLY_CANCEL and LRU RESIZE
+		 * are not supported by the server, otherwise, it is done on
+		 * enqueue. */
+		if (!exp_connect_cancelset(lock->l_conn_export) &&
+		    !ns_connect_lru_resize(ns))
+			ldlm_cancel_lru(ns, 0, LCF_ASYNC, 0);
+	} else {
+		LDLM_DEBUG(lock, "do not add lock into lru list");
+		unlock_res_and_lock(lock);
+	}
+}
+
+/**
+ * Decrease reader/writer refcount for LDLM lock with handle \a lockh
+ */
+void ldlm_lock_decref(struct lustre_handle *lockh, __u32 mode)
+{
+	struct ldlm_lock *lock = __ldlm_handle2lock(lockh, 0);
+
+	LASSERTF(lock != NULL, "Non-existing lock: %#llx\n", lockh->cookie);
+	ldlm_lock_decref_internal(lock, mode);
+	LDLM_LOCK_PUT(lock);
+}
+EXPORT_SYMBOL(ldlm_lock_decref);
+
+/**
+ * Decrease reader/writer refcount for LDLM lock with handle
+ * \a lockh and mark it for subsequent cancellation once r/w refcount
+ * drops to zero instead of putting into LRU.
+ *
+ * Typical usage is for GROUP locks which we cannot allow to be cached.
+ */
+void ldlm_lock_decref_and_cancel(struct lustre_handle *lockh, __u32 mode)
+{
+	struct ldlm_lock *lock = __ldlm_handle2lock(lockh, 0);
+
+	LASSERT(lock != NULL);
+
+	LDLM_DEBUG(lock, "ldlm_lock_decref(%s)", ldlm_lockname[mode]);
+	lock_res_and_lock(lock);
+	lock->l_flags |= LDLM_FL_CBPENDING;
+	unlock_res_and_lock(lock);
+	ldlm_lock_decref_internal(lock, mode);
+	LDLM_LOCK_PUT(lock);
+}
+EXPORT_SYMBOL(ldlm_lock_decref_and_cancel);
+
+struct sl_insert_point {
+	struct list_head *res_link;
+	struct list_head *mode_link;
+	struct list_head *policy_link;
+};
+
+/**
+ * Finds a position to insert the new lock into granted lock list.
+ *
+ * Used for locks eligible for skiplist optimization.
+ *
+ * Parameters:
+ *      queue [input]:  the granted list where search acts on;
+ *      req [input]:    the lock whose position to be located;
+ *      prev [output]:  positions within 3 lists to insert @req to
+ * Return Value:
+ *      filled @prev
+ * NOTE: called by
+ *  - ldlm_grant_lock_with_skiplist
+ */
+static void search_granted_lock(struct list_head *queue,
+				struct ldlm_lock *req,
+				struct sl_insert_point *prev)
+{
+	struct list_head *tmp;
+	struct ldlm_lock *lock, *mode_end, *policy_end;
+
+	list_for_each(tmp, queue) {
+		lock = list_entry(tmp, struct ldlm_lock, l_res_link);
+
+		mode_end = list_entry(lock->l_sl_mode.prev,
+					  struct ldlm_lock, l_sl_mode);
+
+		if (lock->l_req_mode != req->l_req_mode) {
+			/* jump to last lock of mode group */
+			tmp = &mode_end->l_res_link;
+			continue;
+		}
+
+		/* suitable mode group is found */
+		if (lock->l_resource->lr_type == LDLM_PLAIN) {
+			/* insert point is last lock of the mode group */
+			prev->res_link = &mode_end->l_res_link;
+			prev->mode_link = &mode_end->l_sl_mode;
+			prev->policy_link = &req->l_sl_policy;
+			return;
+		} else if (lock->l_resource->lr_type == LDLM_IBITS) {
+			for (;;) {
+				policy_end =
+					list_entry(lock->l_sl_policy.prev,
+						       struct ldlm_lock,
+						       l_sl_policy);
+
+				if (lock->l_policy_data.l_inodebits.bits ==
+				    req->l_policy_data.l_inodebits.bits) {
+					/* insert point is last lock of
+					 * the policy group */
+					prev->res_link =
+						&policy_end->l_res_link;
+					prev->mode_link =
+						&policy_end->l_sl_mode;
+					prev->policy_link =
+						&policy_end->l_sl_policy;
+					return;
+				}
+
+				if (policy_end == mode_end)
+					/* done with mode group */
+					break;
+
+				/* go to next policy group within mode group */
+				tmp = policy_end->l_res_link.next;
+				lock = list_entry(tmp, struct ldlm_lock,
+						      l_res_link);
+			}  /* loop over policy groups within the mode group */
+
+			/* insert point is last lock of the mode group,
+			 * new policy group is started */
+			prev->res_link = &mode_end->l_res_link;
+			prev->mode_link = &mode_end->l_sl_mode;
+			prev->policy_link = &req->l_sl_policy;
+			return;
+		} else {
+			LDLM_ERROR(lock,
+				   "is not LDLM_PLAIN or LDLM_IBITS lock");
+			LBUG();
+		}
+	}
+
+	/* insert point is last lock on the queue,
+	 * new mode group and new policy group are started */
+	prev->res_link = queue->prev;
+	prev->mode_link = &req->l_sl_mode;
+	prev->policy_link = &req->l_sl_policy;
+}
+
+/**
+ * Add a lock into resource granted list after a position described by
+ * \a prev.
+ */
+static void ldlm_granted_list_add_lock(struct ldlm_lock *lock,
+				       struct sl_insert_point *prev)
+{
+	struct ldlm_resource *res = lock->l_resource;
+
+	check_res_locked(res);
+
+	ldlm_resource_dump(D_INFO, res);
+	LDLM_DEBUG(lock, "About to add lock:");
+
+	if (lock->l_flags & LDLM_FL_DESTROYED) {
+		CDEBUG(D_OTHER, "Lock destroyed, not adding to resource\n");
+		return;
+	}
+
+	LASSERT(list_empty(&lock->l_res_link));
+	LASSERT(list_empty(&lock->l_sl_mode));
+	LASSERT(list_empty(&lock->l_sl_policy));
+
+	/*
+	 * lock->link == prev->link means lock is first starting the group.
+	 * Don't re-add to itself to suppress kernel warnings.
+	 */
+	if (&lock->l_res_link != prev->res_link)
+		list_add(&lock->l_res_link, prev->res_link);
+	if (&lock->l_sl_mode != prev->mode_link)
+		list_add(&lock->l_sl_mode, prev->mode_link);
+	if (&lock->l_sl_policy != prev->policy_link)
+		list_add(&lock->l_sl_policy, prev->policy_link);
+}
+
+/**
+ * Add a lock to granted list on a resource maintaining skiplist
+ * correctness.
+ */
+static void ldlm_grant_lock_with_skiplist(struct ldlm_lock *lock)
+{
+	struct sl_insert_point prev;
+
+	LASSERT(lock->l_req_mode == lock->l_granted_mode);
+
+	search_granted_lock(&lock->l_resource->lr_granted, lock, &prev);
+	ldlm_granted_list_add_lock(lock, &prev);
+}
+
+/**
+ * Perform lock granting bookkeeping.
+ *
+ * Includes putting the lock into granted list and updating lock mode.
+ * NOTE: called by
+ *  - ldlm_lock_enqueue
+ *  - ldlm_reprocess_queue
+ *  - ldlm_lock_convert
+ *
+ * must be called with lr_lock held
+ */
+void ldlm_grant_lock(struct ldlm_lock *lock, struct list_head *work_list)
+{
+	struct ldlm_resource *res = lock->l_resource;
+
+	check_res_locked(res);
+
+	lock->l_granted_mode = lock->l_req_mode;
+	if (res->lr_type == LDLM_PLAIN || res->lr_type == LDLM_IBITS)
+		ldlm_grant_lock_with_skiplist(lock);
+	else if (res->lr_type == LDLM_EXTENT)
+		ldlm_extent_add_lock(res, lock);
+	else
+		ldlm_resource_add_lock(res, &res->lr_granted, lock);
+
+	if (lock->l_granted_mode < res->lr_most_restr)
+		res->lr_most_restr = lock->l_granted_mode;
+
+	if (work_list && lock->l_completion_ast != NULL)
+		ldlm_add_ast_work_item(lock, NULL, work_list);
+
+	ldlm_pool_add(&ldlm_res_to_ns(res)->ns_pool, lock);
+}
+
+/**
+ * Search for a lock with given properties in a queue.
+ *
+ * \retval a referenced lock or NULL.  See the flag descriptions below, in the
+ * comment above ldlm_lock_match
+ */
+static struct ldlm_lock *search_queue(struct list_head *queue,
+				      ldlm_mode_t *mode,
+				      ldlm_policy_data_t *policy,
+				      struct ldlm_lock *old_lock,
+				      __u64 flags, int unref)
+{
+	struct ldlm_lock *lock;
+	struct list_head       *tmp;
+
+	list_for_each(tmp, queue) {
+		ldlm_mode_t match;
+
+		lock = list_entry(tmp, struct ldlm_lock, l_res_link);
+
+		if (lock == old_lock)
+			break;
+
+		/* Check if this lock can be matched.
+		 * Used by LU-2919(exclusive open) for open lease lock */
+		if (ldlm_is_excl(lock))
+			continue;
+
+		/* llite sometimes wants to match locks that will be
+		 * canceled when their users drop, but we allow it to match
+		 * if it passes in CBPENDING and the lock still has users.
+		 * this is generally only going to be used by children
+		 * whose parents already hold a lock so forward progress
+		 * can still happen. */
+		if (lock->l_flags & LDLM_FL_CBPENDING &&
+		    !(flags & LDLM_FL_CBPENDING))
+			continue;
+		if (!unref && lock->l_flags & LDLM_FL_CBPENDING &&
+		    lock->l_readers == 0 && lock->l_writers == 0)
+			continue;
+
+		if (!(lock->l_req_mode & *mode))
+			continue;
+		match = lock->l_req_mode;
+
+		if (lock->l_resource->lr_type == LDLM_EXTENT &&
+		    (lock->l_policy_data.l_extent.start >
+		     policy->l_extent.start ||
+		     lock->l_policy_data.l_extent.end < policy->l_extent.end))
+			continue;
+
+		if (unlikely(match == LCK_GROUP) &&
+		    lock->l_resource->lr_type == LDLM_EXTENT &&
+		    lock->l_policy_data.l_extent.gid != policy->l_extent.gid)
+			continue;
+
+		/* We match if we have existing lock with same or wider set
+		   of bits. */
+		if (lock->l_resource->lr_type == LDLM_IBITS &&
+		     ((lock->l_policy_data.l_inodebits.bits &
+		      policy->l_inodebits.bits) !=
+		      policy->l_inodebits.bits))
+			continue;
+
+		if (!unref && (lock->l_flags & LDLM_FL_GONE_MASK))
+			continue;
+
+		if ((flags & LDLM_FL_LOCAL_ONLY) &&
+		    !(lock->l_flags & LDLM_FL_LOCAL))
+			continue;
+
+		if (flags & LDLM_FL_TEST_LOCK) {
+			LDLM_LOCK_GET(lock);
+			ldlm_lock_touch_in_lru(lock);
+		} else {
+			ldlm_lock_addref_internal_nolock(lock, match);
+		}
+		*mode = match;
+		return lock;
+	}
+
+	return NULL;
+}
+
+void ldlm_lock_fail_match_locked(struct ldlm_lock *lock)
+{
+	if ((lock->l_flags & LDLM_FL_FAIL_NOTIFIED) == 0) {
+		lock->l_flags |= LDLM_FL_FAIL_NOTIFIED;
+		wake_up_all(&lock->l_waitq);
+	}
+}
+EXPORT_SYMBOL(ldlm_lock_fail_match_locked);
+
+void ldlm_lock_fail_match(struct ldlm_lock *lock)
+{
+	lock_res_and_lock(lock);
+	ldlm_lock_fail_match_locked(lock);
+	unlock_res_and_lock(lock);
+}
+EXPORT_SYMBOL(ldlm_lock_fail_match);
+
+/**
+ * Mark lock as "matchable" by OST.
+ *
+ * Used to prevent certain races in LOV/OSC where the lock is granted, but LVB
+ * is not yet valid.
+ * Assumes LDLM lock is already locked.
+ */
+void ldlm_lock_allow_match_locked(struct ldlm_lock *lock)
+{
+	lock->l_flags |= LDLM_FL_LVB_READY;
+	wake_up_all(&lock->l_waitq);
+}
+EXPORT_SYMBOL(ldlm_lock_allow_match_locked);
+
+/**
+ * Mark lock as "matchable" by OST.
+ * Locks the lock and then \see ldlm_lock_allow_match_locked
+ */
+void ldlm_lock_allow_match(struct ldlm_lock *lock)
+{
+	lock_res_and_lock(lock);
+	ldlm_lock_allow_match_locked(lock);
+	unlock_res_and_lock(lock);
+}
+EXPORT_SYMBOL(ldlm_lock_allow_match);
+
+/**
+ * Attempt to find a lock with specified properties.
+ *
+ * Typically returns a reference to matched lock unless LDLM_FL_TEST_LOCK is
+ * set in \a flags
+ *
+ * Can be called in two ways:
+ *
+ * If 'ns' is NULL, then lockh describes an existing lock that we want to look
+ * for a duplicate of.
+ *
+ * Otherwise, all of the fields must be filled in, to match against.
+ *
+ * If 'flags' contains LDLM_FL_LOCAL_ONLY, then only match local locks on the
+ *     server (ie, connh is NULL)
+ * If 'flags' contains LDLM_FL_BLOCK_GRANTED, then only locks on the granted
+ *     list will be considered
+ * If 'flags' contains LDLM_FL_CBPENDING, then locks that have been marked
+ *     to be canceled can still be matched as long as they still have reader
+ *     or writer referneces
+ * If 'flags' contains LDLM_FL_TEST_LOCK, then don't actually reference a lock,
+ *     just tell us if we would have matched.
+ *
+ * \retval 1 if it finds an already-existing lock that is compatible; in this
+ * case, lockh is filled in with a addref()ed lock
+ *
+ * We also check security context, and if that fails we simply return 0 (to
+ * keep caller code unchanged), the context failure will be discovered by
+ * caller sometime later.
+ */
+ldlm_mode_t ldlm_lock_match(struct ldlm_namespace *ns, __u64 flags,
+			    const struct ldlm_res_id *res_id, ldlm_type_t type,
+			    ldlm_policy_data_t *policy, ldlm_mode_t mode,
+			    struct lustre_handle *lockh, int unref)
+{
+	struct ldlm_resource *res;
+	struct ldlm_lock *lock, *old_lock = NULL;
+	int rc = 0;
+
+	if (ns == NULL) {
+		old_lock = ldlm_handle2lock(lockh);
+		LASSERT(old_lock);
+
+		ns = ldlm_lock_to_ns(old_lock);
+		res_id = &old_lock->l_resource->lr_name;
+		type = old_lock->l_resource->lr_type;
+		mode = old_lock->l_req_mode;
+	}
+
+	res = ldlm_resource_get(ns, NULL, res_id, type, 0);
+	if (res == NULL) {
+		LASSERT(old_lock == NULL);
+		return 0;
+	}
+
+	LDLM_RESOURCE_ADDREF(res);
+	lock_res(res);
+
+	lock = search_queue(&res->lr_granted, &mode, policy, old_lock,
+			    flags, unref);
+	if (lock != NULL) {
+		rc = 1;
+		goto out;
+	}
+	if (flags & LDLM_FL_BLOCK_GRANTED) {
+		rc = 0;
+		goto out;
+	}
+	lock = search_queue(&res->lr_converting, &mode, policy, old_lock,
+			    flags, unref);
+	if (lock != NULL) {
+		rc = 1;
+		goto out;
+	}
+	lock = search_queue(&res->lr_waiting, &mode, policy, old_lock,
+			    flags, unref);
+	if (lock != NULL) {
+		rc = 1;
+		goto out;
+	}
+
+ out:
+	unlock_res(res);
+	LDLM_RESOURCE_DELREF(res);
+	ldlm_resource_putref(res);
+
+	if (lock) {
+		ldlm_lock2handle(lock, lockh);
+		if ((flags & LDLM_FL_LVB_READY) &&
+		    (!(lock->l_flags & LDLM_FL_LVB_READY))) {
+			__u64 wait_flags = LDLM_FL_LVB_READY |
+				LDLM_FL_DESTROYED | LDLM_FL_FAIL_NOTIFIED;
+			struct l_wait_info lwi;
+
+			if (lock->l_completion_ast) {
+				int err = lock->l_completion_ast(lock,
+							  LDLM_FL_WAIT_NOREPROC,
+								 NULL);
+				if (err) {
+					if (flags & LDLM_FL_TEST_LOCK)
+						LDLM_LOCK_RELEASE(lock);
+					else
+						ldlm_lock_decref_internal(lock,
+									  mode);
+					rc = 0;
+					goto out2;
+				}
+			}
+
+			lwi = LWI_TIMEOUT_INTR(cfs_time_seconds(obd_timeout),
+					       NULL, LWI_ON_SIGNAL_NOOP, NULL);
+
+			/* XXX FIXME see comment on CAN_MATCH in lustre_dlm.h */
+			l_wait_event(lock->l_waitq,
+				     lock->l_flags & wait_flags,
+				     &lwi);
+			if (!(lock->l_flags & LDLM_FL_LVB_READY)) {
+				if (flags & LDLM_FL_TEST_LOCK)
+					LDLM_LOCK_RELEASE(lock);
+				else
+					ldlm_lock_decref_internal(lock, mode);
+				rc = 0;
+			}
+		}
+	}
+ out2:
+	if (rc) {
+		LDLM_DEBUG(lock, "matched (%llu %llu)",
+			   (type == LDLM_PLAIN || type == LDLM_IBITS) ?
+				res_id->name[2] : policy->l_extent.start,
+			   (type == LDLM_PLAIN || type == LDLM_IBITS) ?
+				res_id->name[3] : policy->l_extent.end);
+
+		/* check user's security context */
+		if (lock->l_conn_export &&
+		    sptlrpc_import_check_ctx(
+				class_exp2cliimp(lock->l_conn_export))) {
+			if (!(flags & LDLM_FL_TEST_LOCK))
+				ldlm_lock_decref_internal(lock, mode);
+			rc = 0;
+		}
+
+		if (flags & LDLM_FL_TEST_LOCK)
+			LDLM_LOCK_RELEASE(lock);
+
+	} else if (!(flags & LDLM_FL_TEST_LOCK)) {/*less verbose for test-only*/
+		LDLM_DEBUG_NOLOCK("not matched ns %p type %u mode %u res %llu/%llu (%llu %llu)",
+				  ns, type, mode, res_id->name[0],
+				  res_id->name[1],
+				  (type == LDLM_PLAIN || type == LDLM_IBITS) ?
+					res_id->name[2] : policy->l_extent.start,
+				  (type == LDLM_PLAIN || type == LDLM_IBITS) ?
+					res_id->name[3] : policy->l_extent.end);
+	}
+	if (old_lock)
+		LDLM_LOCK_PUT(old_lock);
+
+	return rc ? mode : 0;
+}
+EXPORT_SYMBOL(ldlm_lock_match);
+
+ldlm_mode_t ldlm_revalidate_lock_handle(struct lustre_handle *lockh,
+					__u64 *bits)
+{
+	struct ldlm_lock *lock;
+	ldlm_mode_t mode = 0;
+
+	lock = ldlm_handle2lock(lockh);
+	if (lock != NULL) {
+		lock_res_and_lock(lock);
+		if (lock->l_flags & LDLM_FL_GONE_MASK)
+			goto out;
+
+		if (lock->l_flags & LDLM_FL_CBPENDING &&
+		    lock->l_readers == 0 && lock->l_writers == 0)
+			goto out;
+
+		if (bits)
+			*bits = lock->l_policy_data.l_inodebits.bits;
+		mode = lock->l_granted_mode;
+		ldlm_lock_addref_internal_nolock(lock, mode);
+	}
+
+out:
+	if (lock != NULL) {
+		unlock_res_and_lock(lock);
+		LDLM_LOCK_PUT(lock);
+	}
+	return mode;
+}
+EXPORT_SYMBOL(ldlm_revalidate_lock_handle);
+
+/** The caller must guarantee that the buffer is large enough. */
+int ldlm_fill_lvb(struct ldlm_lock *lock, struct req_capsule *pill,
+		  enum req_location loc, void *data, int size)
+{
+	void *lvb;
+
+	LASSERT(data != NULL);
+	LASSERT(size >= 0);
+
+	switch (lock->l_lvb_type) {
+	case LVB_T_OST:
+		if (size == sizeof(struct ost_lvb)) {
+			if (loc == RCL_CLIENT)
+				lvb = req_capsule_client_swab_get(pill,
+						&RMF_DLM_LVB,
+						lustre_swab_ost_lvb);
+			else
+				lvb = req_capsule_server_swab_get(pill,
+						&RMF_DLM_LVB,
+						lustre_swab_ost_lvb);
+			if (unlikely(lvb == NULL)) {
+				LDLM_ERROR(lock, "no LVB");
+				return -EPROTO;
+			}
+
+			memcpy(data, lvb, size);
+		} else if (size == sizeof(struct ost_lvb_v1)) {
+			struct ost_lvb *olvb = data;
+
+			if (loc == RCL_CLIENT)
+				lvb = req_capsule_client_swab_get(pill,
+						&RMF_DLM_LVB,
+						lustre_swab_ost_lvb_v1);
+			else
+				lvb = req_capsule_server_sized_swab_get(pill,
+						&RMF_DLM_LVB, size,
+						lustre_swab_ost_lvb_v1);
+			if (unlikely(lvb == NULL)) {
+				LDLM_ERROR(lock, "no LVB");
+				return -EPROTO;
+			}
+
+			memcpy(data, lvb, size);
+			olvb->lvb_mtime_ns = 0;
+			olvb->lvb_atime_ns = 0;
+			olvb->lvb_ctime_ns = 0;
+		} else {
+			LDLM_ERROR(lock, "Replied unexpected ost LVB size %d",
+				   size);
+			return -EINVAL;
+		}
+		break;
+	case LVB_T_LQUOTA:
+		if (size == sizeof(struct lquota_lvb)) {
+			if (loc == RCL_CLIENT)
+				lvb = req_capsule_client_swab_get(pill,
+						&RMF_DLM_LVB,
+						lustre_swab_lquota_lvb);
+			else
+				lvb = req_capsule_server_swab_get(pill,
+						&RMF_DLM_LVB,
+						lustre_swab_lquota_lvb);
+			if (unlikely(lvb == NULL)) {
+				LDLM_ERROR(lock, "no LVB");
+				return -EPROTO;
+			}
+
+			memcpy(data, lvb, size);
+		} else {
+			LDLM_ERROR(lock,
+				   "Replied unexpected lquota LVB size %d",
+				   size);
+			return -EINVAL;
+		}
+		break;
+	case LVB_T_LAYOUT:
+		if (size == 0)
+			break;
+
+		if (loc == RCL_CLIENT)
+			lvb = req_capsule_client_get(pill, &RMF_DLM_LVB);
+		else
+			lvb = req_capsule_server_get(pill, &RMF_DLM_LVB);
+		if (unlikely(lvb == NULL)) {
+			LDLM_ERROR(lock, "no LVB");
+			return -EPROTO;
+		}
+
+		memcpy(data, lvb, size);
+		break;
+	default:
+		LDLM_ERROR(lock, "Unknown LVB type: %d\n", lock->l_lvb_type);
+		dump_stack();
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/**
+ * Create and fill in new LDLM lock with specified properties.
+ * Returns a referenced lock
+ */
+struct ldlm_lock *ldlm_lock_create(struct ldlm_namespace *ns,
+				   const struct ldlm_res_id *res_id,
+				   ldlm_type_t type,
+				   ldlm_mode_t mode,
+				   const struct ldlm_callback_suite *cbs,
+				   void *data, __u32 lvb_len,
+				   enum lvb_type lvb_type)
+{
+	struct ldlm_lock *lock;
+	struct ldlm_resource *res;
+
+	res = ldlm_resource_get(ns, NULL, res_id, type, 1);
+	if (res == NULL)
+		return NULL;
+
+	lock = ldlm_lock_new(res);
+
+	if (lock == NULL)
+		return NULL;
+
+	lock->l_req_mode = mode;
+	lock->l_ast_data = data;
+	lock->l_pid = current_pid();
+	if (ns_is_server(ns))
+		lock->l_flags |= LDLM_FL_NS_SRV;
+	if (cbs) {
+		lock->l_blocking_ast = cbs->lcs_blocking;
+		lock->l_completion_ast = cbs->lcs_completion;
+		lock->l_glimpse_ast = cbs->lcs_glimpse;
+	}
+
+	lock->l_tree_node = NULL;
+	/* if this is the extent lock, allocate the interval tree node */
+	if (type == LDLM_EXTENT) {
+		if (ldlm_interval_alloc(lock) == NULL)
+			goto out;
+	}
+
+	if (lvb_len) {
+		lock->l_lvb_len = lvb_len;
+		OBD_ALLOC(lock->l_lvb_data, lvb_len);
+		if (lock->l_lvb_data == NULL)
+			goto out;
+	}
+
+	lock->l_lvb_type = lvb_type;
+	if (OBD_FAIL_CHECK(OBD_FAIL_LDLM_NEW_LOCK))
+		goto out;
+
+	return lock;
+
+out:
+	ldlm_lock_destroy(lock);
+	LDLM_LOCK_RELEASE(lock);
+	return NULL;
+}
+
+/**
+ * Enqueue (request) a lock.
+ *
+ * Does not block. As a result of enqueue the lock would be put
+ * into granted or waiting list.
+ *
+ * If namespace has intent policy sent and the lock has LDLM_FL_HAS_INTENT flag
+ * set, skip all the enqueueing and delegate lock processing to intent policy
+ * function.
+ */
+ldlm_error_t ldlm_lock_enqueue(struct ldlm_namespace *ns,
+			       struct ldlm_lock **lockp,
+			       void *cookie, __u64 *flags)
+{
+	struct ldlm_lock *lock = *lockp;
+	struct ldlm_resource *res = lock->l_resource;
+	int local = ns_is_client(ldlm_res_to_ns(res));
+	ldlm_error_t rc = ELDLM_OK;
+	struct ldlm_interval *node = NULL;
+
+	lock->l_last_activity = get_seconds();
+	/* policies are not executed on the client or during replay */
+	if ((*flags & (LDLM_FL_HAS_INTENT|LDLM_FL_REPLAY)) == LDLM_FL_HAS_INTENT
+	    && !local && ns->ns_policy) {
+		rc = ns->ns_policy(ns, lockp, cookie, lock->l_req_mode, *flags,
+				   NULL);
+		if (rc == ELDLM_LOCK_REPLACED) {
+			/* The lock that was returned has already been granted,
+			 * and placed into lockp.  If it's not the same as the
+			 * one we passed in, then destroy the old one and our
+			 * work here is done. */
+			if (lock != *lockp) {
+				ldlm_lock_destroy(lock);
+				LDLM_LOCK_RELEASE(lock);
+			}
+			*flags |= LDLM_FL_LOCK_CHANGED;
+			return 0;
+		} else if (rc != ELDLM_OK ||
+			   (rc == ELDLM_OK && (*flags & LDLM_FL_INTENT_ONLY))) {
+			ldlm_lock_destroy(lock);
+			return rc;
+		}
+	}
+
+	/* For a replaying lock, it might be already in granted list. So
+	 * unlinking the lock will cause the interval node to be freed, we
+	 * have to allocate the interval node early otherwise we can't regrant
+	 * this lock in the future. - jay */
+	if (!local && (*flags & LDLM_FL_REPLAY) && res->lr_type == LDLM_EXTENT)
+		OBD_SLAB_ALLOC_PTR_GFP(node, ldlm_interval_slab, GFP_NOFS);
+
+	lock_res_and_lock(lock);
+	if (local && lock->l_req_mode == lock->l_granted_mode) {
+		/* The server returned a blocked lock, but it was granted
+		 * before we got a chance to actually enqueue it.  We don't
+		 * need to do anything else. */
+		*flags &= ~(LDLM_FL_BLOCK_GRANTED |
+			    LDLM_FL_BLOCK_CONV | LDLM_FL_BLOCK_WAIT);
+		goto out;
+	}
+
+	ldlm_resource_unlink_lock(lock);
+	if (res->lr_type == LDLM_EXTENT && lock->l_tree_node == NULL) {
+		if (node == NULL) {
+			ldlm_lock_destroy_nolock(lock);
+			rc = -ENOMEM;
+			goto out;
+		}
+
+		INIT_LIST_HEAD(&node->li_group);
+		ldlm_interval_attach(node, lock);
+		node = NULL;
+	}
+
+	/* Some flags from the enqueue want to make it into the AST, via the
+	 * lock's l_flags. */
+	lock->l_flags |= *flags & LDLM_FL_AST_DISCARD_DATA;
+
+	/* This distinction between local lock trees is very important; a client
+	 * namespace only has information about locks taken by that client, and
+	 * thus doesn't have enough information to decide for itself if it can
+	 * be granted (below).  In this case, we do exactly what the server
+	 * tells us to do, as dictated by the 'flags'.
+	 *
+	 * We do exactly the same thing during recovery, when the server is
+	 * more or less trusting the clients not to lie.
+	 *
+	 * FIXME (bug 268): Detect obvious lies by checking compatibility in
+	 * granted/converting queues. */
+	if (local) {
+		if (*flags & LDLM_FL_BLOCK_CONV)
+			ldlm_resource_add_lock(res, &res->lr_converting, lock);
+		else if (*flags & (LDLM_FL_BLOCK_WAIT | LDLM_FL_BLOCK_GRANTED))
+			ldlm_resource_add_lock(res, &res->lr_waiting, lock);
+		else
+			ldlm_grant_lock(lock, NULL);
+		goto out;
+	} else {
+		CERROR("This is client-side-only module, cannot handle LDLM_NAMESPACE_SERVER resource type lock.\n");
+		LBUG();
+	}
+
+out:
+	unlock_res_and_lock(lock);
+	if (node)
+		OBD_SLAB_FREE(node, ldlm_interval_slab, sizeof(*node));
+	return rc;
+}
+
+
+/**
+ * Process a call to blocking AST callback for a lock in ast_work list
+ */
+static int
+ldlm_work_bl_ast_lock(struct ptlrpc_request_set *rqset, void *opaq)
+{
+	struct ldlm_cb_set_arg *arg = opaq;
+	struct ldlm_lock_desc   d;
+	int		     rc;
+	struct ldlm_lock       *lock;
+
+	if (list_empty(arg->list))
+		return -ENOENT;
+
+	lock = list_entry(arg->list->next, struct ldlm_lock, l_bl_ast);
+
+	/* nobody should touch l_bl_ast */
+	lock_res_and_lock(lock);
+	list_del_init(&lock->l_bl_ast);
+
+	LASSERT(lock->l_flags & LDLM_FL_AST_SENT);
+	LASSERT(lock->l_bl_ast_run == 0);
+	LASSERT(lock->l_blocking_lock);
+	lock->l_bl_ast_run++;
+	unlock_res_and_lock(lock);
+
+	ldlm_lock2desc(lock->l_blocking_lock, &d);
+
+	rc = lock->l_blocking_ast(lock, &d, (void *)arg, LDLM_CB_BLOCKING);
+	LDLM_LOCK_RELEASE(lock->l_blocking_lock);
+	lock->l_blocking_lock = NULL;
+	LDLM_LOCK_RELEASE(lock);
+
+	return rc;
+}
+
+/**
+ * Process a call to completion AST callback for a lock in ast_work list
+ */
+static int
+ldlm_work_cp_ast_lock(struct ptlrpc_request_set *rqset, void *opaq)
+{
+	struct ldlm_cb_set_arg  *arg = opaq;
+	int		      rc = 0;
+	struct ldlm_lock	*lock;
+	ldlm_completion_callback completion_callback;
+
+	if (list_empty(arg->list))
+		return -ENOENT;
+
+	lock = list_entry(arg->list->next, struct ldlm_lock, l_cp_ast);
+
+	/* It's possible to receive a completion AST before we've set
+	 * the l_completion_ast pointer: either because the AST arrived
+	 * before the reply, or simply because there's a small race
+	 * window between receiving the reply and finishing the local
+	 * enqueue. (bug 842)
+	 *
+	 * This can't happen with the blocking_ast, however, because we
+	 * will never call the local blocking_ast until we drop our
+	 * reader/writer reference, which we won't do until we get the
+	 * reply and finish enqueueing. */
+
+	/* nobody should touch l_cp_ast */
+	lock_res_and_lock(lock);
+	list_del_init(&lock->l_cp_ast);
+	LASSERT(lock->l_flags & LDLM_FL_CP_REQD);
+	/* save l_completion_ast since it can be changed by
+	 * mds_intent_policy(), see bug 14225 */
+	completion_callback = lock->l_completion_ast;
+	lock->l_flags &= ~LDLM_FL_CP_REQD;
+	unlock_res_and_lock(lock);
+
+	if (completion_callback != NULL)
+		rc = completion_callback(lock, 0, (void *)arg);
+	LDLM_LOCK_RELEASE(lock);
+
+	return rc;
+}
+
+/**
+ * Process a call to revocation AST callback for a lock in ast_work list
+ */
+static int
+ldlm_work_revoke_ast_lock(struct ptlrpc_request_set *rqset, void *opaq)
+{
+	struct ldlm_cb_set_arg *arg = opaq;
+	struct ldlm_lock_desc   desc;
+	int		     rc;
+	struct ldlm_lock       *lock;
+
+	if (list_empty(arg->list))
+		return -ENOENT;
+
+	lock = list_entry(arg->list->next, struct ldlm_lock, l_rk_ast);
+	list_del_init(&lock->l_rk_ast);
+
+	/* the desc just pretend to exclusive */
+	ldlm_lock2desc(lock, &desc);
+	desc.l_req_mode = LCK_EX;
+	desc.l_granted_mode = 0;
+
+	rc = lock->l_blocking_ast(lock, &desc, (void *)arg, LDLM_CB_BLOCKING);
+	LDLM_LOCK_RELEASE(lock);
+
+	return rc;
+}
+
+/**
+ * Process a call to glimpse AST callback for a lock in ast_work list
+ */
+int ldlm_work_gl_ast_lock(struct ptlrpc_request_set *rqset, void *opaq)
+{
+	struct ldlm_cb_set_arg		*arg = opaq;
+	struct ldlm_glimpse_work	*gl_work;
+	struct ldlm_lock		*lock;
+	int				 rc = 0;
+
+	if (list_empty(arg->list))
+		return -ENOENT;
+
+	gl_work = list_entry(arg->list->next, struct ldlm_glimpse_work,
+				 gl_list);
+	list_del_init(&gl_work->gl_list);
+
+	lock = gl_work->gl_lock;
+
+	/* transfer the glimpse descriptor to ldlm_cb_set_arg */
+	arg->gl_desc = gl_work->gl_desc;
+
+	/* invoke the actual glimpse callback */
+	if (lock->l_glimpse_ast(lock, (void *)arg) == 0)
+		rc = 1;
+
+	LDLM_LOCK_RELEASE(lock);
+
+	if ((gl_work->gl_flags & LDLM_GL_WORK_NOFREE) == 0)
+		OBD_FREE_PTR(gl_work);
+
+	return rc;
+}
+
+/**
+ * Process list of locks in need of ASTs being sent.
+ *
+ * Used on server to send multiple ASTs together instead of sending one by
+ * one.
+ */
+int ldlm_run_ast_work(struct ldlm_namespace *ns, struct list_head *rpc_list,
+		      enum ldlm_desc_ast_t ast_type)
+{
+	struct ldlm_cb_set_arg *arg;
+	set_producer_func       work_ast_lock;
+	int		     rc;
+
+	if (list_empty(rpc_list))
+		return 0;
+
+	OBD_ALLOC_PTR(arg);
+	if (arg == NULL)
+		return -ENOMEM;
+
+	atomic_set(&arg->restart, 0);
+	arg->list = rpc_list;
+
+	switch (ast_type) {
+	case LDLM_WORK_BL_AST:
+		arg->type = LDLM_BL_CALLBACK;
+		work_ast_lock = ldlm_work_bl_ast_lock;
+		break;
+	case LDLM_WORK_CP_AST:
+		arg->type = LDLM_CP_CALLBACK;
+		work_ast_lock = ldlm_work_cp_ast_lock;
+		break;
+	case LDLM_WORK_REVOKE_AST:
+		arg->type = LDLM_BL_CALLBACK;
+		work_ast_lock = ldlm_work_revoke_ast_lock;
+		break;
+	case LDLM_WORK_GL_AST:
+		arg->type = LDLM_GL_CALLBACK;
+		work_ast_lock = ldlm_work_gl_ast_lock;
+		break;
+	default:
+		LBUG();
+	}
+
+	/* We create a ptlrpc request set with flow control extension.
+	 * This request set will use the work_ast_lock function to produce new
+	 * requests and will send a new request each time one completes in order
+	 * to keep the number of requests in flight to ns_max_parallel_ast */
+	arg->set = ptlrpc_prep_fcset(ns->ns_max_parallel_ast ? : UINT_MAX,
+				     work_ast_lock, arg);
+	if (arg->set == NULL) {
+		rc = -ENOMEM;
+		goto out;
+	}
+
+	ptlrpc_set_wait(arg->set);
+	ptlrpc_set_destroy(arg->set);
+
+	rc = atomic_read(&arg->restart) ? -ERESTART : 0;
+	goto out;
+out:
+	OBD_FREE_PTR(arg);
+	return rc;
+}
+
+static int reprocess_one_queue(struct ldlm_resource *res, void *closure)
+{
+	ldlm_reprocess_all(res);
+	return LDLM_ITER_CONTINUE;
+}
+
+static int ldlm_reprocess_res(struct cfs_hash *hs, struct cfs_hash_bd *bd,
+			      struct hlist_node *hnode, void *arg)
+{
+	struct ldlm_resource *res = cfs_hash_object(hs, hnode);
+	int    rc;
+
+	rc = reprocess_one_queue(res, arg);
+
+	return rc == LDLM_ITER_STOP;
+}
+
+/**
+ * Iterate through all resources on a namespace attempting to grant waiting
+ * locks.
+ */
+void ldlm_reprocess_all_ns(struct ldlm_namespace *ns)
+{
+	if (ns != NULL) {
+		cfs_hash_for_each_nolock(ns->ns_rs_hash,
+					 ldlm_reprocess_res, NULL);
+	}
+}
+EXPORT_SYMBOL(ldlm_reprocess_all_ns);
+
+/**
+ * Try to grant all waiting locks on a resource.
+ *
+ * Calls ldlm_reprocess_queue on converting and waiting queues.
+ *
+ * Typically called after some resource locks are cancelled to see
+ * if anything could be granted as a result of the cancellation.
+ */
+void ldlm_reprocess_all(struct ldlm_resource *res)
+{
+	LIST_HEAD(rpc_list);
+
+	if (!ns_is_client(ldlm_res_to_ns(res))) {
+		CERROR("This is client-side-only module, cannot handle LDLM_NAMESPACE_SERVER resource type lock.\n");
+		LBUG();
+	}
+}
+
+/**
+ * Helper function to call blocking AST for LDLM lock \a lock in a
+ * "cancelling" mode.
+ */
+void ldlm_cancel_callback(struct ldlm_lock *lock)
+{
+	check_res_locked(lock->l_resource);
+	if (!(lock->l_flags & LDLM_FL_CANCEL)) {
+		lock->l_flags |= LDLM_FL_CANCEL;
+		if (lock->l_blocking_ast) {
+			unlock_res_and_lock(lock);
+			lock->l_blocking_ast(lock, NULL, lock->l_ast_data,
+					     LDLM_CB_CANCELING);
+			lock_res_and_lock(lock);
+		} else {
+			LDLM_DEBUG(lock, "no blocking ast");
+		}
+	}
+	lock->l_flags |= LDLM_FL_BL_DONE;
+}
+
+/**
+ * Remove skiplist-enabled LDLM lock \a req from granted list
+ */
+void ldlm_unlink_lock_skiplist(struct ldlm_lock *req)
+{
+	if (req->l_resource->lr_type != LDLM_PLAIN &&
+	    req->l_resource->lr_type != LDLM_IBITS)
+		return;
+
+	list_del_init(&req->l_sl_policy);
+	list_del_init(&req->l_sl_mode);
+}
+
+/**
+ * Attempts to cancel LDLM lock \a lock that has no reader/writer references.
+ */
+void ldlm_lock_cancel(struct ldlm_lock *lock)
+{
+	struct ldlm_resource *res;
+	struct ldlm_namespace *ns;
+
+	lock_res_and_lock(lock);
+
+	res = lock->l_resource;
+	ns  = ldlm_res_to_ns(res);
+
+	/* Please do not, no matter how tempting, remove this LBUG without
+	 * talking to me first. -phik */
+	if (lock->l_readers || lock->l_writers) {
+		LDLM_ERROR(lock, "lock still has references");
+		LBUG();
+	}
+
+	if (lock->l_flags & LDLM_FL_WAITED)
+		ldlm_del_waiting_lock(lock);
+
+	/* Releases cancel callback. */
+	ldlm_cancel_callback(lock);
+
+	/* Yes, second time, just in case it was added again while we were
+	 * running with no res lock in ldlm_cancel_callback */
+	if (lock->l_flags & LDLM_FL_WAITED)
+		ldlm_del_waiting_lock(lock);
+
+	ldlm_resource_unlink_lock(lock);
+	ldlm_lock_destroy_nolock(lock);
+
+	if (lock->l_granted_mode == lock->l_req_mode)
+		ldlm_pool_del(&ns->ns_pool, lock);
+
+	/* Make sure we will not be called again for same lock what is possible
+	 * if not to zero out lock->l_granted_mode */
+	lock->l_granted_mode = LCK_MINMODE;
+	unlock_res_and_lock(lock);
+}
+EXPORT_SYMBOL(ldlm_lock_cancel);
+
+/**
+ * Set opaque data into the lock that only makes sense to upper layer.
+ */
+int ldlm_lock_set_data(struct lustre_handle *lockh, void *data)
+{
+	struct ldlm_lock *lock = ldlm_handle2lock(lockh);
+	int rc = -EINVAL;
+
+	if (lock) {
+		if (lock->l_ast_data == NULL)
+			lock->l_ast_data = data;
+		if (lock->l_ast_data == data)
+			rc = 0;
+		LDLM_LOCK_PUT(lock);
+	}
+	return rc;
+}
+EXPORT_SYMBOL(ldlm_lock_set_data);
+
+struct export_cl_data {
+	struct obd_export	*ecl_exp;
+	int			ecl_loop;
+};
+
+/**
+ * Iterator function for ldlm_cancel_locks_for_export.
+ * Cancels passed locks.
+ */
+int ldlm_cancel_locks_for_export_cb(struct cfs_hash *hs, struct cfs_hash_bd *bd,
+				    struct hlist_node *hnode, void *data)
+
+{
+	struct export_cl_data	*ecl = (struct export_cl_data *)data;
+	struct obd_export	*exp  = ecl->ecl_exp;
+	struct ldlm_lock     *lock = cfs_hash_object(hs, hnode);
+	struct ldlm_resource *res;
+
+	res = ldlm_resource_getref(lock->l_resource);
+	LDLM_LOCK_GET(lock);
+
+	LDLM_DEBUG(lock, "export %p", exp);
+	ldlm_res_lvbo_update(res, NULL, 1);
+	ldlm_lock_cancel(lock);
+	ldlm_reprocess_all(res);
+	ldlm_resource_putref(res);
+	LDLM_LOCK_RELEASE(lock);
+
+	ecl->ecl_loop++;
+	if ((ecl->ecl_loop & -ecl->ecl_loop) == ecl->ecl_loop) {
+		CDEBUG(D_INFO,
+		       "Cancel lock %p for export %p (loop %d), still have %d locks left on hash table.\n",
+		       lock, exp, ecl->ecl_loop,
+		       atomic_read(&hs->hs_count));
+	}
+
+	return 0;
+}
+
+/**
+ * Cancel all locks for given export.
+ *
+ * Typically called on client disconnection/eviction
+ */
+void ldlm_cancel_locks_for_export(struct obd_export *exp)
+{
+	struct export_cl_data	ecl = {
+		.ecl_exp	= exp,
+		.ecl_loop	= 0,
+	};
+
+	cfs_hash_for_each_empty(exp->exp_lock_hash,
+				ldlm_cancel_locks_for_export_cb, &ecl);
+}
+
+/**
+ * Downgrade an exclusive lock.
+ *
+ * A fast variant of ldlm_lock_convert for conversion of exclusive
+ * locks. The conversion is always successful.
+ * Used by Commit on Sharing (COS) code.
+ *
+ * \param lock A lock to convert
+ * \param new_mode new lock mode
+ */
+void ldlm_lock_downgrade(struct ldlm_lock *lock, int new_mode)
+{
+	LASSERT(lock->l_granted_mode & (LCK_PW | LCK_EX));
+	LASSERT(new_mode == LCK_COS);
+
+	lock_res_and_lock(lock);
+	ldlm_resource_unlink_lock(lock);
+	/*
+	 * Remove the lock from pool as it will be added again in
+	 * ldlm_grant_lock() called below.
+	 */
+	ldlm_pool_del(&ldlm_lock_to_ns(lock)->ns_pool, lock);
+
+	lock->l_req_mode = new_mode;
+	ldlm_grant_lock(lock, NULL);
+	unlock_res_and_lock(lock);
+	ldlm_reprocess_all(lock->l_resource);
+}
+EXPORT_SYMBOL(ldlm_lock_downgrade);
+
+/**
+ * Attempt to convert already granted lock to a different mode.
+ *
+ * While lock conversion is not currently used, future client-side
+ * optimizations could take advantage of it to avoid discarding cached
+ * pages on a file.
+ */
+struct ldlm_resource *ldlm_lock_convert(struct ldlm_lock *lock, int new_mode,
+					__u32 *flags)
+{
+	LIST_HEAD(rpc_list);
+	struct ldlm_resource *res;
+	struct ldlm_namespace *ns;
+	int granted = 0;
+	struct ldlm_interval *node;
+
+	/* Just return if mode is unchanged. */
+	if (new_mode == lock->l_granted_mode) {
+		*flags |= LDLM_FL_BLOCK_GRANTED;
+		return lock->l_resource;
+	}
+
+	/* I can't check the type of lock here because the bitlock of lock
+	 * is not held here, so do the allocation blindly. -jay */
+	OBD_SLAB_ALLOC_PTR_GFP(node, ldlm_interval_slab, GFP_NOFS);
+	if (node == NULL)
+		/* Actually, this causes EDEADLOCK to be returned */
+		return NULL;
+
+	LASSERTF((new_mode == LCK_PW && lock->l_granted_mode == LCK_PR),
+		 "new_mode %u, granted %u\n", new_mode, lock->l_granted_mode);
+
+	lock_res_and_lock(lock);
+
+	res = lock->l_resource;
+	ns  = ldlm_res_to_ns(res);
+
+	lock->l_req_mode = new_mode;
+	if (res->lr_type == LDLM_PLAIN || res->lr_type == LDLM_IBITS) {
+		ldlm_resource_unlink_lock(lock);
+	} else {
+		ldlm_resource_unlink_lock(lock);
+		if (res->lr_type == LDLM_EXTENT) {
+			/* FIXME: ugly code, I have to attach the lock to a
+			 * interval node again since perhaps it will be granted
+			 * soon */
+			INIT_LIST_HEAD(&node->li_group);
+			ldlm_interval_attach(node, lock);
+			node = NULL;
+		}
+	}
+
+	/*
+	 * Remove old lock from the pool before adding the lock with new
+	 * mode below in ->policy()
+	 */
+	ldlm_pool_del(&ns->ns_pool, lock);
+
+	/* If this is a local resource, put it on the appropriate list. */
+	if (ns_is_client(ldlm_res_to_ns(res))) {
+		if (*flags & (LDLM_FL_BLOCK_CONV | LDLM_FL_BLOCK_GRANTED)) {
+			ldlm_resource_add_lock(res, &res->lr_converting, lock);
+		} else {
+			/* This should never happen, because of the way the
+			 * server handles conversions. */
+			LDLM_ERROR(lock, "Erroneous flags %x on local lock\n",
+				   *flags);
+			LBUG();
+
+			ldlm_grant_lock(lock, &rpc_list);
+			granted = 1;
+			/* FIXME: completion handling not with lr_lock held ! */
+			if (lock->l_completion_ast)
+				lock->l_completion_ast(lock, 0, NULL);
+		}
+	} else {
+		CERROR("This is client-side-only module, cannot handle LDLM_NAMESPACE_SERVER resource type lock.\n");
+		LBUG();
+	}
+	unlock_res_and_lock(lock);
+
+	if (granted)
+		ldlm_run_ast_work(ns, &rpc_list, LDLM_WORK_CP_AST);
+	if (node)
+		OBD_SLAB_FREE(node, ldlm_interval_slab, sizeof(*node));
+	return res;
+}
+EXPORT_SYMBOL(ldlm_lock_convert);
+
+/**
+ * Print lock with lock handle \a lockh description into debug log.
+ *
+ * Used when printing all locks on a resource for debug purposes.
+ */
+void ldlm_lock_dump_handle(int level, struct lustre_handle *lockh)
+{
+	struct ldlm_lock *lock;
+
+	if (!((libcfs_debug | D_ERROR) & level))
+		return;
+
+	lock = ldlm_handle2lock(lockh);
+	if (lock == NULL)
+		return;
+
+	LDLM_DEBUG_LIMIT(level, lock, "###");
+
+	LDLM_LOCK_PUT(lock);
+}
+EXPORT_SYMBOL(ldlm_lock_dump_handle);
+
+/**
+ * Print lock information with custom message into debug log.
+ * Helper function.
+ */
+void _ldlm_lock_debug(struct ldlm_lock *lock,
+		      struct libcfs_debug_msg_data *msgdata,
+		      const char *fmt, ...)
+{
+	va_list args;
+	struct obd_export *exp = lock->l_export;
+	struct ldlm_resource *resource = lock->l_resource;
+	char *nid = "local";
+
+	va_start(args, fmt);
+
+	if (exp && exp->exp_connection) {
+		nid = libcfs_nid2str(exp->exp_connection->c_peer.nid);
+	} else if (exp && exp->exp_obd != NULL) {
+		struct obd_import *imp = exp->exp_obd->u.cli.cl_import;
+
+		nid = libcfs_nid2str(imp->imp_connection->c_peer.nid);
+	}
+
+	if (resource == NULL) {
+		libcfs_debug_vmsg2(msgdata, fmt, args,
+				   " ns: \?\? lock: %p/%#llx lrc: %d/%d,%d mode: %s/%s res: \?\? rrc=\?\? type: \?\?\? flags: %#llx nid: %s remote: %#llx expref: %d pid: %u timeout: %lu lvb_type: %d\n",
+				   lock,
+				   lock->l_handle.h_cookie, atomic_read(&lock->l_refc),
+				   lock->l_readers, lock->l_writers,
+				   ldlm_lockname[lock->l_granted_mode],
+				   ldlm_lockname[lock->l_req_mode],
+				   lock->l_flags, nid, lock->l_remote_handle.cookie,
+				   exp ? atomic_read(&exp->exp_refcount) : -99,
+				   lock->l_pid, lock->l_callback_timeout, lock->l_lvb_type);
+		va_end(args);
+		return;
+	}
+
+	switch (resource->lr_type) {
+	case LDLM_EXTENT:
+		libcfs_debug_vmsg2(msgdata, fmt, args,
+				   " ns: %s lock: %p/%#llx lrc: %d/%d,%d mode: %s/%s res: " DLDLMRES " rrc: %d type: %s [%llu->%llu] (req %llu->%llu) flags: %#llx nid: %s remote: %#llx expref: %d pid: %u timeout: %lu lvb_type: %d\n",
+				   ldlm_lock_to_ns_name(lock), lock,
+				   lock->l_handle.h_cookie, atomic_read(&lock->l_refc),
+				   lock->l_readers, lock->l_writers,
+				   ldlm_lockname[lock->l_granted_mode],
+				   ldlm_lockname[lock->l_req_mode],
+				   PLDLMRES(resource),
+				   atomic_read(&resource->lr_refcount),
+				   ldlm_typename[resource->lr_type],
+				   lock->l_policy_data.l_extent.start,
+				   lock->l_policy_data.l_extent.end,
+				   lock->l_req_extent.start, lock->l_req_extent.end,
+				   lock->l_flags, nid, lock->l_remote_handle.cookie,
+				   exp ? atomic_read(&exp->exp_refcount) : -99,
+				   lock->l_pid, lock->l_callback_timeout,
+				   lock->l_lvb_type);
+		break;
+
+	case LDLM_FLOCK:
+		libcfs_debug_vmsg2(msgdata, fmt, args,
+				   " ns: %s lock: %p/%#llx lrc: %d/%d,%d mode: %s/%s res: " DLDLMRES " rrc: %d type: %s pid: %d [%llu->%llu] flags: %#llx nid: %s remote: %#llx expref: %d pid: %u timeout: %lu\n",
+				   ldlm_lock_to_ns_name(lock), lock,
+				   lock->l_handle.h_cookie, atomic_read(&lock->l_refc),
+				   lock->l_readers, lock->l_writers,
+				   ldlm_lockname[lock->l_granted_mode],
+				   ldlm_lockname[lock->l_req_mode],
+				   PLDLMRES(resource),
+				   atomic_read(&resource->lr_refcount),
+				   ldlm_typename[resource->lr_type],
+				   lock->l_policy_data.l_flock.pid,
+				   lock->l_policy_data.l_flock.start,
+				   lock->l_policy_data.l_flock.end,
+				   lock->l_flags, nid, lock->l_remote_handle.cookie,
+				   exp ? atomic_read(&exp->exp_refcount) : -99,
+				   lock->l_pid, lock->l_callback_timeout);
+		break;
+
+	case LDLM_IBITS:
+		libcfs_debug_vmsg2(msgdata, fmt, args,
+				   " ns: %s lock: %p/%#llx lrc: %d/%d,%d mode: %s/%s res: " DLDLMRES " bits %#llx rrc: %d type: %s flags: %#llx nid: %s remote: %#llx expref: %d pid: %u timeout: %lu lvb_type: %d\n",
+				   ldlm_lock_to_ns_name(lock),
+				   lock, lock->l_handle.h_cookie,
+				   atomic_read(&lock->l_refc),
+				   lock->l_readers, lock->l_writers,
+				   ldlm_lockname[lock->l_granted_mode],
+				   ldlm_lockname[lock->l_req_mode],
+				   PLDLMRES(resource),
+				   lock->l_policy_data.l_inodebits.bits,
+				   atomic_read(&resource->lr_refcount),
+				   ldlm_typename[resource->lr_type],
+				   lock->l_flags, nid, lock->l_remote_handle.cookie,
+				   exp ? atomic_read(&exp->exp_refcount) : -99,
+				   lock->l_pid, lock->l_callback_timeout,
+				   lock->l_lvb_type);
+		break;
+
+	default:
+		libcfs_debug_vmsg2(msgdata, fmt, args,
+				   " ns: %s lock: %p/%#llx lrc: %d/%d,%d mode: %s/%s res: " DLDLMRES " rrc: %d type: %s flags: %#llx nid: %s remote: %#llx expref: %d pid: %u timeout: %lu lvb_type: %d\n",
+				   ldlm_lock_to_ns_name(lock),
+				   lock, lock->l_handle.h_cookie,
+				   atomic_read(&lock->l_refc),
+				   lock->l_readers, lock->l_writers,
+				   ldlm_lockname[lock->l_granted_mode],
+				   ldlm_lockname[lock->l_req_mode],
+				   PLDLMRES(resource),
+				   atomic_read(&resource->lr_refcount),
+				   ldlm_typename[resource->lr_type],
+				   lock->l_flags, nid, lock->l_remote_handle.cookie,
+				   exp ? atomic_read(&exp->exp_refcount) : -99,
+				   lock->l_pid, lock->l_callback_timeout,
+				   lock->l_lvb_type);
+		break;
+	}
+	va_end(args);
+}
+EXPORT_SYMBOL(_ldlm_lock_debug);