Whamcloud - gitweb
LU-1061 agl: cl_locks_prune() waits for the last user
[fs/lustre-release.git] / lustre / obdclass / cl_lock.c
index 190a941..4202603 100644 (file)
  * GPL HEADER END
  */
 /*
- * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
+ * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  * Use is subject to license terms.
+ *
+ * Copyright (c) 2011 Whamcloud, Inc.
+ *
  */
 /*
  * This file is part of Lustre, http://www.lustre.org/
@@ -54,7 +57,7 @@
 #include "cl_internal.h"
 
 /** Lock class of cl_lock::cll_guard */
-static struct lock_class_key cl_lock_guard_class;
+static cfs_lock_class_key_t cl_lock_guard_class;
 static cfs_mem_cache_t *cl_lock_kmem;
 
 static struct lu_kmem_descr cl_lock_caches[] = {
@@ -77,10 +80,8 @@ static struct lu_kmem_descr cl_lock_caches[] = {
 static int cl_lock_invariant_trusted(const struct lu_env *env,
                                      const struct cl_lock *lock)
 {
-        return
-                cl_is_lock(lock) &&
-                ergo(lock->cll_state == CLS_FREEING, lock->cll_holds == 0) &&
-                atomic_read(&lock->cll_ref) >= lock->cll_holds &&
+        return  ergo(lock->cll_state == CLS_FREEING, lock->cll_holds == 0) &&
+                cfs_atomic_read(&lock->cll_ref) >= lock->cll_holds &&
                 lock->cll_holds >= lock->cll_users &&
                 lock->cll_holds >= 0 &&
                 lock->cll_users >= 0 &&
@@ -97,7 +98,7 @@ static int cl_lock_invariant(const struct lu_env *env,
 {
         int result;
 
-        result = atomic_read(&lock->cll_ref) > 0 &&
+        result = cfs_atomic_read(&lock->cll_ref) > 0 &&
                 cl_lock_invariant_trusted(env, lock);
         if (!result && env != NULL)
                 CL_LOCK_DEBUG(D_ERROR, env, lock, "invariant broken");
@@ -132,10 +133,10 @@ static void cl_lock_trace0(int level, const struct lu_env *env,
                            const char *func, const int line)
 {
         struct cl_object_header *h = cl_object_header(lock->cll_descr.cld_obj);
-        CDEBUG(level, "%s: %p@(%i %p %i %d %d %d %d %lx)"
-                      "(%p/%d/%i) at %s():%d\n",
-               prefix, lock,
-               atomic_read(&lock->cll_ref), lock->cll_guarder, lock->cll_depth,
+        CDEBUG(level, "%s: %p@(%d %p %d %d %d %d %d %lx)"
+                      "(%p/%d/%d) at %s():%d\n",
+               prefix, lock, cfs_atomic_read(&lock->cll_ref),
+               lock->cll_guarder, lock->cll_depth,
                lock->cll_state, lock->cll_error, lock->cll_holds,
                lock->cll_users, lock->cll_flags,
                env, h->coh_nesting, cl_lock_nr_mutexed(env),
@@ -147,7 +148,7 @@ static void cl_lock_trace0(int level, const struct lu_env *env,
 #define RETIP ((unsigned long)__builtin_return_address(0))
 
 #ifdef CONFIG_LOCKDEP
-static struct lock_class_key cl_lock_key;
+static cfs_lock_class_key_t cl_lock_key;
 
 static void cl_lock_lockdep_init(struct cl_lock *lock)
 {
@@ -158,9 +159,13 @@ static void cl_lock_lockdep_acquire(const struct lu_env *env,
                                     struct cl_lock *lock, __u32 enqflags)
 {
         cl_lock_counters(env, lock)->ctc_nr_locks_acquired++;
+#ifdef HAVE_LOCK_MAP_ACQUIRE
+        lock_map_acquire(&lock->dep_map);
+#else  /* HAVE_LOCK_MAP_ACQUIRE */
         lock_acquire(&lock->dep_map, !!(enqflags & CEF_ASYNC),
                      /* try: */ 0, lock->cll_descr.cld_mode <= CLM_READ,
                      /* check: */ 2, RETIP);
+#endif /* HAVE_LOCK_MAP_ACQUIRE */
 }
 
 static void cl_lock_lockdep_release(const struct lu_env *env,
@@ -198,7 +203,7 @@ void cl_lock_slice_add(struct cl_lock *lock, struct cl_lock_slice *slice,
 {
         ENTRY;
         slice->cls_lock = lock;
-        list_add_tail(&slice->cls_linkage, &lock->cll_layers);
+        cfs_list_add_tail(&slice->cls_linkage, &lock->cll_layers);
         slice->cls_obj = obj;
         slice->cls_ops = ops;
         EXIT;
@@ -257,27 +262,26 @@ static void cl_lock_free(const struct lu_env *env, struct cl_lock *lock)
 {
         struct cl_object *obj = lock->cll_descr.cld_obj;
 
-        LASSERT(cl_is_lock(lock));
         LINVRNT(!cl_lock_is_mutexed(lock));
 
         ENTRY;
         cl_lock_trace(D_DLMTRACE, env, "free lock", lock);
-        might_sleep();
-        while (!list_empty(&lock->cll_layers)) {
+        cfs_might_sleep();
+        while (!cfs_list_empty(&lock->cll_layers)) {
                 struct cl_lock_slice *slice;
 
-                slice = list_entry(lock->cll_layers.next, struct cl_lock_slice,
-                                   cls_linkage);
-                list_del_init(lock->cll_layers.next);
+                slice = cfs_list_entry(lock->cll_layers.next,
+                                       struct cl_lock_slice, cls_linkage);
+                cfs_list_del_init(lock->cll_layers.next);
                 slice->cls_ops->clo_fini(env, slice);
         }
-        atomic_dec(&cl_object_site(obj)->cs_locks.cs_total);
-        atomic_dec(&cl_object_site(obj)->cs_locks_state[lock->cll_state]);
+        cfs_atomic_dec(&cl_object_site(obj)->cs_locks.cs_total);
+        cfs_atomic_dec(&cl_object_site(obj)->cs_locks_state[lock->cll_state]);
         lu_object_ref_del_at(&obj->co_lu, lock->cll_obj_ref, "cl_lock", lock);
         cl_object_put(env, obj);
         lu_ref_fini(&lock->cll_reference);
         lu_ref_fini(&lock->cll_holders);
-        mutex_destroy(&lock->cll_guard);
+        cfs_mutex_destroy(&lock->cll_guard);
         OBD_SLAB_FREE_PTR(lock, cl_lock_kmem);
         EXIT;
 }
@@ -294,25 +298,23 @@ static void cl_lock_free(const struct lu_env *env, struct cl_lock *lock)
 void cl_lock_put(const struct lu_env *env, struct cl_lock *lock)
 {
         struct cl_object        *obj;
-        struct cl_object_header *head;
         struct cl_site          *site;
 
         LINVRNT(cl_lock_invariant(env, lock));
         ENTRY;
         obj = lock->cll_descr.cld_obj;
         LINVRNT(obj != NULL);
-        head = cl_object_header(obj);
         site = cl_object_site(obj);
 
         CDEBUG(D_TRACE, "releasing reference: %d %p %lu\n",
-               atomic_read(&lock->cll_ref), lock, RETIP);
+               cfs_atomic_read(&lock->cll_ref), lock, RETIP);
 
-        if (atomic_dec_and_test(&lock->cll_ref)) {
+        if (cfs_atomic_dec_and_test(&lock->cll_ref)) {
                 if (lock->cll_state == CLS_FREEING) {
-                        LASSERT(list_empty(&lock->cll_linkage));
+                        LASSERT(cfs_list_empty(&lock->cll_linkage));
                         cl_lock_free(env, lock);
                 }
-                atomic_dec(&site->cs_locks.cs_busy);
+                cfs_atomic_dec(&site->cs_locks.cs_busy);
         }
         EXIT;
 }
@@ -330,8 +332,8 @@ void cl_lock_get(struct cl_lock *lock)
 {
         LINVRNT(cl_lock_invariant(NULL, lock));
         CDEBUG(D_TRACE, "acquiring reference: %d %p %lu\n",
-               atomic_read(&lock->cll_ref), lock, RETIP);
-        atomic_inc(&lock->cll_ref);
+               cfs_atomic_read(&lock->cll_ref), lock, RETIP);
+        cfs_atomic_inc(&lock->cll_ref);
 }
 EXPORT_SYMBOL(cl_lock_get);
 
@@ -348,11 +350,10 @@ void cl_lock_get_trust(struct cl_lock *lock)
 {
         struct cl_site *site = cl_object_site(lock->cll_descr.cld_obj);
 
-        LASSERT(cl_is_lock(lock));
         CDEBUG(D_TRACE, "acquiring trusted reference: %d %p %lu\n",
-               atomic_read(&lock->cll_ref), lock, RETIP);
-        if (atomic_inc_return(&lock->cll_ref) == 1)
-                atomic_inc(&site->cs_locks.cs_busy);
+               cfs_atomic_read(&lock->cll_ref), lock, RETIP);
+        if (cfs_atomic_inc_return(&lock->cll_ref) == 1)
+                cfs_atomic_inc(&site->cs_locks.cs_busy);
 }
 EXPORT_SYMBOL(cl_lock_get_trust);
 
@@ -383,7 +384,7 @@ static struct cl_lock *cl_lock_alloc(const struct lu_env *env,
         ENTRY;
         OBD_SLAB_ALLOC_PTR_GFP(lock, cl_lock_kmem, CFS_ALLOC_IO);
         if (lock != NULL) {
-                atomic_set(&lock->cll_ref, 1);
+                cfs_atomic_set(&lock->cll_ref, 1);
                 lock->cll_descr = *descr;
                 lock->cll_state = CLS_NEW;
                 cl_object_get(obj);
@@ -394,15 +395,16 @@ static struct cl_lock *cl_lock_alloc(const struct lu_env *env,
                 CFS_INIT_LIST_HEAD(&lock->cll_inclosure);
                 lu_ref_init(&lock->cll_reference);
                 lu_ref_init(&lock->cll_holders);
-                mutex_init(&lock->cll_guard);
-                lockdep_set_class(&lock->cll_guard, &cl_lock_guard_class);
+                cfs_mutex_init(&lock->cll_guard);
+                cfs_lockdep_set_class(&lock->cll_guard, &cl_lock_guard_class);
                 cfs_waitq_init(&lock->cll_wq);
                 head = obj->co_lu.lo_header;
-                atomic_inc(&site->cs_locks_state[CLS_NEW]);
-                atomic_inc(&site->cs_locks.cs_total);
-                atomic_inc(&site->cs_locks.cs_created);
+                cfs_atomic_inc(&site->cs_locks_state[CLS_NEW]);
+                cfs_atomic_inc(&site->cs_locks.cs_total);
+                cfs_atomic_inc(&site->cs_locks.cs_created);
                 cl_lock_lockdep_init(lock);
-                list_for_each_entry(obj, &head->loh_layers, co_lu.lo_linkage) {
+                cfs_list_for_each_entry(obj, &head->loh_layers,
+                                        co_lu.lo_linkage) {
                         int err;
 
                         err = obj->co_ops->coo_lock_init(env, obj, lock, io);
@@ -482,7 +484,7 @@ static int cl_lock_fits_into(const struct lu_env *env,
 
         LINVRNT(cl_lock_invariant_trusted(env, lock));
         ENTRY;
-        list_for_each_entry(slice, &lock->cll_layers, cls_linkage) {
+        cfs_list_for_each_entry(slice, &lock->cll_layers, cls_linkage) {
                 if (slice->cls_ops->clo_fits_into != NULL &&
                     !slice->cls_ops->clo_fits_into(env, slice, need, io))
                         RETURN(0);
@@ -504,24 +506,21 @@ static struct cl_lock *cl_lock_lookup(const struct lu_env *env,
         head = cl_object_header(obj);
         site = cl_object_site(obj);
         LINVRNT_SPIN_LOCKED(&head->coh_lock_guard);
-        atomic_inc(&site->cs_locks.cs_lookup);
-        list_for_each_entry(lock, &head->coh_locks, cll_linkage) {
+        cfs_atomic_inc(&site->cs_locks.cs_lookup);
+        cfs_list_for_each_entry(lock, &head->coh_locks, cll_linkage) {
                 int matched;
 
-                LASSERT(cl_is_lock(lock));
                 matched = cl_lock_ext_match(&lock->cll_descr, need) &&
                           lock->cll_state < CLS_FREEING &&
                           lock->cll_error == 0 &&
                           !(lock->cll_flags & CLF_CANCELLED) &&
                           cl_lock_fits_into(env, lock, need, io);
-                CDEBUG(D_DLMTRACE, "has: "DDESCR"(%i) need: "DDESCR": %d\n",
+                CDEBUG(D_DLMTRACE, "has: "DDESCR"(%d) need: "DDESCR": %d\n",
                        PDESCR(&lock->cll_descr), lock->cll_state, PDESCR(need),
                        matched);
                 if (matched) {
                         cl_lock_get_trust(lock);
-                        /* move the lock to the LRU head */
-                        list_move(&lock->cll_linkage, &head->coh_locks);
-                        atomic_inc(&cl_object_site(obj)->cs_locks.cs_hit);
+                        cfs_atomic_inc(&cl_object_site(obj)->cs_locks.cs_hit);
                         RETURN(lock);
                 }
         }
@@ -553,23 +552,24 @@ static struct cl_lock *cl_lock_find(const struct lu_env *env,
         head = cl_object_header(obj);
         site = cl_object_site(obj);
 
-        spin_lock(&head->coh_lock_guard);
+        cfs_spin_lock(&head->coh_lock_guard);
         lock = cl_lock_lookup(env, obj, io, need);
-        spin_unlock(&head->coh_lock_guard);
+        cfs_spin_unlock(&head->coh_lock_guard);
 
         if (lock == NULL) {
                 lock = cl_lock_alloc(env, obj, io, need);
                 if (!IS_ERR(lock)) {
                         struct cl_lock *ghost;
 
-                        spin_lock(&head->coh_lock_guard);
+                        cfs_spin_lock(&head->coh_lock_guard);
                         ghost = cl_lock_lookup(env, obj, io, need);
                         if (ghost == NULL) {
-                                list_add(&lock->cll_linkage, &head->coh_locks);
-                                spin_unlock(&head->coh_lock_guard);
-                                atomic_inc(&site->cs_locks.cs_busy);
+                                cfs_list_add_tail(&lock->cll_linkage,
+                                                  &head->coh_locks);
+                                cfs_spin_unlock(&head->coh_lock_guard);
+                                cfs_atomic_inc(&site->cs_locks.cs_busy);
                         } else {
-                                spin_unlock(&head->coh_lock_guard);
+                                cfs_spin_unlock(&head->coh_lock_guard);
                                 /*
                                  * Other threads can acquire references to the
                                  * top-lock through its sub-locks. Hence, it
@@ -600,9 +600,9 @@ struct cl_lock *cl_lock_peek(const struct lu_env *env, const struct cl_io *io,
         obj  = need->cld_obj;
         head = cl_object_header(obj);
 
-        spin_lock(&head->coh_lock_guard);
+        cfs_spin_lock(&head->coh_lock_guard);
         lock = cl_lock_lookup(env, obj, io, need);
-        spin_unlock(&head->coh_lock_guard);
+        cfs_spin_unlock(&head->coh_lock_guard);
 
         if (lock == NULL)
                 return NULL;
@@ -646,7 +646,7 @@ const struct cl_lock_slice *cl_lock_at(const struct cl_lock *lock,
         LINVRNT(cl_lock_invariant_trusted(NULL, lock));
         ENTRY;
 
-        list_for_each_entry(slice, &lock->cll_layers, cls_linkage) {
+        cfs_list_for_each_entry(slice, &lock->cll_layers, cls_linkage) {
                 if (slice->cls_obj->co_lu.lo_dev->ld_type == dtype)
                         RETURN(slice);
         }
@@ -695,7 +695,7 @@ void cl_lock_mutex_get(const struct lu_env *env, struct cl_lock *lock)
                 info = cl_env_info(env);
                 for (i = 0; i < hdr->coh_nesting; ++i)
                         LASSERT(info->clt_counters[i].ctc_nr_locks_locked == 0);
-                mutex_lock_nested(&lock->cll_guard, hdr->coh_nesting);
+                cfs_mutex_lock_nested(&lock->cll_guard, hdr->coh_nesting);
                 lock->cll_guarder = cfs_current();
                 LINVRNT(lock->cll_depth == 0);
         }
@@ -725,7 +725,7 @@ int cl_lock_mutex_try(const struct lu_env *env, struct cl_lock *lock)
         if (lock->cll_guarder == cfs_current()) {
                 LINVRNT(lock->cll_depth > 0);
                 cl_lock_mutex_tail(env, lock);
-        } else if (mutex_trylock(&lock->cll_guard)) {
+        } else if (cfs_mutex_trylock(&lock->cll_guard)) {
                 LINVRNT(lock->cll_depth == 0);
                 lock->cll_guarder = cfs_current();
                 cl_lock_mutex_tail(env, lock);
@@ -759,7 +759,7 @@ void cl_lock_mutex_put(const struct lu_env *env, struct cl_lock *lock)
         counters->ctc_nr_locks_locked--;
         if (--lock->cll_depth == 0) {
                 lock->cll_guarder = NULL;
-                mutex_unlock(&lock->cll_guard);
+                cfs_mutex_unlock(&lock->cll_guard);
         }
 }
 EXPORT_SYMBOL(cl_lock_mutex_put);
@@ -803,8 +803,8 @@ static void cl_lock_cancel0(const struct lu_env *env, struct cl_lock *lock)
                 const struct cl_lock_slice *slice;
 
                 lock->cll_flags |= CLF_CANCELLED;
-                list_for_each_entry_reverse(slice, &lock->cll_layers,
-                                            cls_linkage) {
+                cfs_list_for_each_entry_reverse(slice, &lock->cll_layers,
+                                                cls_linkage) {
                         if (slice->cls_ops->clo_cancel != NULL)
                                 slice->cls_ops->clo_cancel(env, slice);
                 }
@@ -827,16 +827,16 @@ static void cl_lock_delete0(const struct lu_env *env, struct cl_lock *lock)
 
                 head = cl_object_header(lock->cll_descr.cld_obj);
 
-                spin_lock(&head->coh_lock_guard);
-                list_del_init(&lock->cll_linkage);
+                cfs_spin_lock(&head->coh_lock_guard);
+                cfs_list_del_init(&lock->cll_linkage);
 
-                spin_unlock(&head->coh_lock_guard);
+                cfs_spin_unlock(&head->coh_lock_guard);
                 /*
                  * From now on, no new references to this lock can be acquired
                  * by cl_lock_lookup().
                  */
-                list_for_each_entry_reverse(slice, &lock->cll_layers,
-                                            cls_linkage) {
+                cfs_list_for_each_entry_reverse(slice, &lock->cll_layers,
+                                                cls_linkage) {
                         if (slice->cls_ops->clo_delete != NULL)
                                 slice->cls_ops->clo_delete(env, slice);
                 }
@@ -925,7 +925,6 @@ static void cl_lock_hold_release(const struct lu_env *env, struct cl_lock *lock,
         EXIT;
 }
 
-
 /**
  * Waits until lock state is changed.
  *
@@ -948,6 +947,7 @@ static void cl_lock_hold_release(const struct lu_env *env, struct cl_lock *lock,
 int cl_lock_state_wait(const struct lu_env *env, struct cl_lock *lock)
 {
         cfs_waitlink_t waiter;
+        cfs_sigset_t blocked;
         int result;
 
         ENTRY;
@@ -959,18 +959,26 @@ int cl_lock_state_wait(const struct lu_env *env, struct cl_lock *lock)
         cl_lock_trace(D_DLMTRACE, env, "state wait lock", lock);
         result = lock->cll_error;
         if (result == 0) {
+                /* To avoid being interrupted by the 'non-fatal' signals
+                 * (SIGCHLD, for instance), we'd block them temporarily.
+                 * LU-305 */
+                blocked = cfs_block_sigsinv(LUSTRE_FATAL_SIGS);
+
                 cfs_waitlink_init(&waiter);
                 cfs_waitq_add(&lock->cll_wq, &waiter);
-                set_current_state(CFS_TASK_INTERRUPTIBLE);
+                cfs_set_current_state(CFS_TASK_INTERRUPTIBLE);
                 cl_lock_mutex_put(env, lock);
 
                 LASSERT(cl_lock_nr_mutexed(env) == 0);
                 cfs_waitq_wait(&waiter, CFS_TASK_INTERRUPTIBLE);
 
                 cl_lock_mutex_get(env, lock);
-                set_current_state(CFS_TASK_RUNNING);
+                cfs_set_current_state(CFS_TASK_RUNNING);
                 cfs_waitq_del(&lock->cll_wq, &waiter);
                 result = cfs_signal_pending() ? -EINTR : 0;
+
+                /* Restore old blocked signals */
+                cfs_restore_sigs(blocked);
         }
         RETURN(result);
 }
@@ -985,7 +993,7 @@ static void cl_lock_state_signal(const struct lu_env *env, struct cl_lock *lock,
         LINVRNT(cl_lock_is_mutexed(lock));
         LINVRNT(cl_lock_invariant(env, lock));
 
-        list_for_each_entry(slice, &lock->cll_layers, cls_linkage)
+        cfs_list_for_each_entry(slice, &lock->cll_layers, cls_linkage)
                 if (slice->cls_ops->clo_state != NULL)
                         slice->cls_ops->clo_state(env, slice, state);
         cfs_waitq_broadcast(&lock->cll_wq);
@@ -1033,8 +1041,8 @@ void cl_lock_state_set(const struct lu_env *env, struct cl_lock *lock,
                 lock->cll_state == CLS_INTRANSIT);
 
         if (lock->cll_state != state) {
-                atomic_dec(&site->cs_locks_state[lock->cll_state]);
-                atomic_inc(&site->cs_locks_state[state]);
+                cfs_atomic_dec(&site->cs_locks_state[lock->cll_state]);
+                cfs_atomic_inc(&site->cs_locks_state[state]);
 
                 cl_lock_state_signal(env, lock, state);
                 lock->cll_state = state;
@@ -1054,12 +1062,10 @@ static int cl_unuse_try_internal(const struct lu_env *env, struct cl_lock *lock)
                 LINVRNT(cl_lock_is_mutexed(lock));
                 LINVRNT(cl_lock_invariant(env, lock));
                 LASSERT(lock->cll_state == CLS_INTRANSIT);
-                LASSERT(lock->cll_users > 0);
-                LASSERT(lock->cll_holds > 0);
 
                 result = -ENOSYS;
-                list_for_each_entry_reverse(slice, &lock->cll_layers,
-                                            cls_linkage) {
+                cfs_list_for_each_entry_reverse(slice, &lock->cll_layers,
+                                                cls_linkage) {
                         if (slice->cls_ops->clo_unuse != NULL) {
                                 result = slice->cls_ops->clo_unuse(env, slice);
                                 if (result != 0)
@@ -1093,7 +1099,7 @@ int cl_use_try(const struct lu_env *env, struct cl_lock *lock, int atomic)
 
         result = -ENOSYS;
         state = cl_lock_intransit(env, lock);
-        list_for_each_entry(slice, &lock->cll_layers, cls_linkage) {
+        cfs_list_for_each_entry(slice, &lock->cll_layers, cls_linkage) {
                 if (slice->cls_ops->clo_use != NULL) {
                         result = slice->cls_ops->clo_use(env, slice);
                         if (result != 0)
@@ -1146,7 +1152,7 @@ static int cl_enqueue_kick(const struct lu_env *env,
 
         ENTRY;
         result = -ENOSYS;
-        list_for_each_entry(slice, &lock->cll_layers, cls_linkage) {
+        cfs_list_for_each_entry(slice, &lock->cll_layers, cls_linkage) {
                 if (slice->cls_ops->clo_enqueue != NULL) {
                         result = slice->cls_ops->clo_enqueue(env,
                                                              slice, io, flags);
@@ -1223,6 +1229,51 @@ int cl_enqueue_try(const struct lu_env *env, struct cl_lock *lock,
 }
 EXPORT_SYMBOL(cl_enqueue_try);
 
+/**
+ * Cancel the conflicting lock found during previous enqueue.
+ *
+ * \retval 0 conflicting lock has been canceled.
+ * \retval -ve error code.
+ */
+int cl_lock_enqueue_wait(const struct lu_env *env,
+                         struct cl_lock *lock,
+                         int keep_mutex)
+{
+        struct cl_lock  *conflict;
+        int              rc = 0;
+        ENTRY;
+
+        LASSERT(cl_lock_is_mutexed(lock));
+        LASSERT(lock->cll_state == CLS_QUEUING);
+        LASSERT(lock->cll_conflict != NULL);
+
+        conflict = lock->cll_conflict;
+        lock->cll_conflict = NULL;
+
+        cl_lock_mutex_put(env, lock);
+        LASSERT(cl_lock_nr_mutexed(env) == 0);
+
+        cl_lock_mutex_get(env, conflict);
+        cl_lock_cancel(env, conflict);
+        cl_lock_delete(env, conflict);
+
+        while (conflict->cll_state != CLS_FREEING) {
+                rc = cl_lock_state_wait(env, conflict);
+                if (rc != 0)
+                        break;
+        }
+        cl_lock_mutex_put(env, conflict);
+        lu_ref_del(&conflict->cll_reference, "cancel-wait", lock);
+        cl_lock_put(env, conflict);
+
+        if (keep_mutex)
+                cl_lock_mutex_get(env, lock);
+
+        LASSERT(rc <= 0);
+        RETURN(rc);
+}
+EXPORT_SYMBOL(cl_lock_enqueue_wait);
+
 static int cl_enqueue_locked(const struct lu_env *env, struct cl_lock *lock,
                              struct cl_io *io, __u32 enqflags)
 {
@@ -1238,7 +1289,10 @@ static int cl_enqueue_locked(const struct lu_env *env, struct cl_lock *lock,
         do {
                 result = cl_enqueue_try(env, lock, io, enqflags);
                 if (result == CLO_WAIT) {
-                        result = cl_lock_state_wait(env, lock);
+                        if (lock->cll_conflict != NULL)
+                                result = cl_lock_enqueue_wait(env, lock, 1);
+                        else
+                                result = cl_lock_state_wait(env, lock);
                         if (result == 0)
                                 continue;
                 }
@@ -1248,7 +1302,8 @@ static int cl_enqueue_locked(const struct lu_env *env, struct cl_lock *lock,
                 cl_lock_user_del(env, lock);
                 cl_lock_error(env, lock, result);
         }
-        LASSERT(ergo(result == 0, lock->cll_state == CLS_ENQUEUED ||
+        LASSERT(ergo(result == 0 && !(enqflags & CEF_AGL),
+                     lock->cll_state == CLS_ENQUEUED ||
                      lock->cll_state == CLS_HELD));
         RETURN(result);
 }
@@ -1425,7 +1480,7 @@ int cl_wait_try(const struct lu_env *env, struct cl_lock *lock)
                         break;
 
                 result = -ENOSYS;
-                list_for_each_entry(slice, &lock->cll_layers, cls_linkage) {
+                cfs_list_for_each_entry(slice, &lock->cll_layers, cls_linkage) {
                         if (slice->cls_ops->clo_wait != NULL) {
                                 result = slice->cls_ops->clo_wait(env, slice);
                                 if (result != 0)
@@ -1462,7 +1517,6 @@ int cl_wait(const struct lu_env *env, struct cl_lock *lock)
         LASSERTF(lock->cll_state == CLS_ENQUEUED || lock->cll_state == CLS_HELD,
                  "Wrong state %d \n", lock->cll_state);
         LASSERT(lock->cll_holds > 0);
-        cl_lock_trace(D_DLMTRACE, env, "wait lock", lock);
 
         do {
                 result = cl_wait_try(env, lock);
@@ -1478,6 +1532,7 @@ int cl_wait(const struct lu_env *env, struct cl_lock *lock)
                 cl_lock_error(env, lock, result);
                 cl_lock_lockdep_release(env, lock);
         }
+        cl_lock_trace(D_DLMTRACE, env, "wait lock", lock);
         cl_lock_mutex_put(env, lock);
         LASSERT(ergo(result == 0, lock->cll_state == CLS_HELD));
         RETURN(result);
@@ -1499,7 +1554,7 @@ unsigned long cl_lock_weigh(const struct lu_env *env, struct cl_lock *lock)
         LINVRNT(cl_lock_invariant(env, lock));
 
         pound = 0;
-        list_for_each_entry_reverse(slice, &lock->cll_layers, cls_linkage) {
+        cfs_list_for_each_entry_reverse(slice, &lock->cll_layers, cls_linkage) {
                 if (slice->cls_ops->clo_weigh != NULL) {
                         ounce = slice->cls_ops->clo_weigh(env, slice);
                         pound += ounce;
@@ -1536,7 +1591,7 @@ int cl_lock_modify(const struct lu_env *env, struct cl_lock *lock,
         LINVRNT(cl_lock_is_mutexed(lock));
         LINVRNT(cl_lock_invariant(env, lock));
 
-        list_for_each_entry_reverse(slice, &lock->cll_layers, cls_linkage) {
+        cfs_list_for_each_entry_reverse(slice, &lock->cll_layers, cls_linkage) {
                 if (slice->cls_ops->clo_modify != NULL) {
                         result = slice->cls_ops->clo_modify(env, slice, desc);
                         if (result != 0)
@@ -1550,9 +1605,9 @@ int cl_lock_modify(const struct lu_env *env, struct cl_lock *lock,
          * now. If locks were indexed according to their extent and/or mode,
          * that index would have to be updated here.
          */
-        spin_lock(&hdr->coh_lock_guard);
+        cfs_spin_lock(&hdr->coh_lock_guard);
         lock->cll_descr = *desc;
-        spin_unlock(&hdr->coh_lock_guard);
+        cfs_spin_unlock(&hdr->coh_lock_guard);
         RETURN(0);
 }
 EXPORT_SYMBOL(cl_lock_modify);
@@ -1598,7 +1653,7 @@ int cl_lock_closure_build(const struct lu_env *env, struct cl_lock *lock,
 
         result = cl_lock_enclosure(env, lock, closure);
         if (result == 0) {
-                list_for_each_entry(slice, &lock->cll_layers, cls_linkage) {
+                cfs_list_for_each_entry(slice, &lock->cll_layers, cls_linkage) {
                         if (slice->cls_ops->clo_closure != NULL) {
                                 result = slice->cls_ops->clo_closure(env, slice,
                                                                      closure);
@@ -1631,10 +1686,10 @@ int cl_lock_enclosure(const struct lu_env *env, struct cl_lock *lock,
                  * If lock->cll_inclosure is not empty, lock is already in
                  * this closure.
                  */
-                if (list_empty(&lock->cll_inclosure)) {
+                if (cfs_list_empty(&lock->cll_inclosure)) {
                         cl_lock_get_trust(lock);
                         lu_ref_add(&lock->cll_reference, "closure", closure);
-                        list_add(&lock->cll_inclosure, &closure->clc_list);
+                        cfs_list_add(&lock->cll_inclosure, &closure->clc_list);
                         closure->clc_nr++;
                 } else
                         cl_lock_mutex_put(env, lock);
@@ -1668,8 +1723,9 @@ void cl_lock_disclosure(const struct lu_env *env,
         struct cl_lock *temp;
 
         cl_lock_trace(D_DLMTRACE, env, "disclosure lock", closure->clc_origin);
-        list_for_each_entry_safe(scan, temp, &closure->clc_list, cll_inclosure){
-                list_del_init(&scan->cll_inclosure);
+        cfs_list_for_each_entry_safe(scan, temp, &closure->clc_list,
+                                     cll_inclosure){
+                cfs_list_del_init(&scan->cll_inclosure);
                 cl_lock_mutex_put(env, scan);
                 lu_ref_del(&scan->cll_reference, "closure", closure);
                 cl_lock_put(env, scan);
@@ -1683,7 +1739,7 @@ EXPORT_SYMBOL(cl_lock_disclosure);
 void cl_lock_closure_fini(struct cl_lock_closure *closure)
 {
         LASSERT(closure->clc_nr == 0);
-        LASSERT(list_empty(&closure->clc_list));
+        LASSERT(cfs_list_empty(&closure->clc_list));
 }
 EXPORT_SYMBOL(cl_lock_closure_fini);
 
@@ -1802,10 +1858,10 @@ struct cl_lock *cl_lock_at_page(const struct lu_env *env, struct cl_object *obj,
         need->cld_start = need->cld_end = page->cp_index;
         need->cld_enq_flags = 0;
 
-        spin_lock(&head->coh_lock_guard);
+        cfs_spin_lock(&head->coh_lock_guard);
         /* It is fine to match any group lock since there could be only one
          * with a uniq gid and it conflicts with all other lock modes too */
-        list_for_each_entry(scan, &head->coh_locks, cll_linkage) {
+        cfs_list_for_each_entry(scan, &head->coh_locks, cll_linkage) {
                 if (scan != except &&
                     (scan->cll_descr.cld_mode == CLM_GROUP ||
                     cl_lock_ext_match(&scan->cll_descr, need)) &&
@@ -1825,74 +1881,85 @@ struct cl_lock *cl_lock_at_page(const struct lu_env *env, struct cl_object *obj,
                         break;
                 }
         }
-        spin_unlock(&head->coh_lock_guard);
+        cfs_spin_unlock(&head->coh_lock_guard);
         RETURN(lock);
 }
 EXPORT_SYMBOL(cl_lock_at_page);
 
 /**
- * Returns a list of pages protected (only) by a given lock.
- *
- * Scans an extent of page radix tree, corresponding to the \a lock and queues
- * all pages that are not protected by locks other than \a lock into \a queue.
+ * Calculate the page offset at the layer of @lock.
+ * At the time of this writing, @page is top page and @lock is sub lock.
  */
-void cl_lock_page_list_fixup(const struct lu_env *env,
-                             struct cl_io *io, struct cl_lock *lock,
-                             struct cl_page_list *queue)
+static pgoff_t pgoff_at_lock(struct cl_page *page, struct cl_lock *lock)
 {
-        struct cl_page        *page;
-        struct cl_page        *temp;
-        struct cl_page_list   *plist = &cl_env_info(env)->clt_list;
-
-        LINVRNT(cl_lock_invariant(env, lock));
-        ENTRY;
+        struct lu_device_type *dtype;
+        const struct cl_page_slice *slice;
 
-        /* Now, we have a list of cl_pages under the \a lock, we need
-         * to check if some of pages are covered by other ldlm lock.
-         * If this is the case, they aren't needed to be written out this time.
-         *
-         * For example, we have A:[0,200] & B:[100,300] PW locks on client, now
-         * the latter is to be canceled, this means other client is
-         * reading/writing [200,300] since A won't canceled. Actually
-         * we just need to write the pages covered by [200,300]. This is safe,
-         * since [100,200] is also protected lock A.
-         */
+        dtype = lock->cll_descr.cld_obj->co_lu.lo_dev->ld_type;
+        slice = cl_page_at(page, dtype);
+        LASSERT(slice != NULL);
+        return slice->cpl_page->cp_index;
+}
 
-        cl_page_list_init(plist);
-        cl_page_list_for_each_safe(page, temp, queue) {
-                pgoff_t                idx = page->cp_index;
-                struct cl_lock        *found;
-                struct cl_lock_descr  *descr;
-
-                /* The algorithm counts on the index-ascending page index. */
-                LASSERT(ergo(&temp->cp_batch != &queue->pl_pages,
-                        page->cp_index < temp->cp_index));
-
-                found = cl_lock_at_page(env, lock->cll_descr.cld_obj,
-                                        page, lock, 0, 0);
-                if (found == NULL)
-                        continue;
-
-                descr = &found->cll_descr;
-                list_for_each_entry_safe_from(page, temp, &queue->pl_pages,
-                                              cp_batch) {
-                        idx = page->cp_index;
-                        if (descr->cld_start > idx || descr->cld_end < idx)
-                                break;
-                        cl_page_list_move(plist, queue, page);
+/**
+ * Check if page @page is covered by an extra lock or discard it.
+ */
+static int check_and_discard_cb(const struct lu_env *env, struct cl_io *io,
+                                struct cl_page *page, void *cbdata)
+{
+        struct cl_thread_info *info = cl_env_info(env);
+        struct cl_lock *lock = cbdata;
+        pgoff_t index = pgoff_at_lock(page, lock);
+
+        if (index >= info->clt_fn_index) {
+                struct cl_lock *tmp;
+
+                /* refresh non-overlapped index */
+                tmp = cl_lock_at_page(env, lock->cll_descr.cld_obj, page, lock,
+                                      1, 0);
+                if (tmp != NULL) {
+                        /* Cache the first-non-overlapped index so as to skip
+                         * all pages within [index, clt_fn_index). This
+                         * is safe because if tmp lock is canceled, it will
+                         * discard these pages. */
+                        info->clt_fn_index = tmp->cll_descr.cld_end + 1;
+                        if (tmp->cll_descr.cld_end == CL_PAGE_EOF)
+                                info->clt_fn_index = CL_PAGE_EOF;
+                        cl_lock_put(env, tmp);
+                } else { /* discard the page */
+                        cl_page_own(env, io, page);
+                        cl_page_unmap(env, io, page);
+                        cl_page_discard(env, io, page);
+                        cl_page_disown(env, io, page);
                 }
-                cl_lock_put(env, found);
         }
 
-        /* The pages in plist are covered by other locks, don't handle them
-         * this time.
-         */
-        if (io != NULL)
-                cl_page_list_disown(env, io, plist);
-        cl_page_list_fini(env, plist);
-        EXIT;
+        info->clt_next_index = index + 1;
+        return CLP_GANG_OKAY;
+}
+
+static int pageout_cb(const struct lu_env *env, struct cl_io *io,
+                      struct cl_page *page, void *cbdata)
+{
+        struct cl_thread_info *info  = cl_env_info(env);
+        struct cl_page_list   *queue = &info->clt_queue.c2_qin;
+        struct cl_lock        *lock  = cbdata;
+        typeof(cl_page_own)   *page_own;
+        int rc = CLP_GANG_OKAY;
+
+        page_own = queue->pl_nr ? cl_page_own_try : cl_page_own;
+        if (page_own(env, io, page) == 0) {
+                cl_page_list_add(queue, page);
+                info->clt_next_index = pgoff_at_lock(page, lock) + 1;
+        } else if (page->cp_state != CPS_FREEING) {
+                /* cl_page_own() won't fail unless
+                 * the page is being freed. */
+                LASSERT(queue->pl_nr != 0);
+                rc = CLP_GANG_AGAIN;
+        }
+
+        return rc;
 }
-EXPORT_SYMBOL(cl_lock_page_list_fixup);
 
 /**
  * Invalidate pages protected by the given lock, sending them out to the
@@ -1923,7 +1990,9 @@ int cl_lock_page_out(const struct lu_env *env, struct cl_lock *lock,
         struct cl_io          *io    = &info->clt_io;
         struct cl_2queue      *queue = &info->clt_queue;
         struct cl_lock_descr  *descr = &lock->cll_descr;
+        cl_page_gang_cb_t      cb;
         long page_count;
+        int res;
         int result;
 
         LINVRNT(cl_lock_invariant(env, lock));
@@ -1931,15 +2000,22 @@ int cl_lock_page_out(const struct lu_env *env, struct cl_lock *lock,
 
         io->ci_obj = cl_object_top(descr->cld_obj);
         result = cl_io_init(env, io, CIT_MISC, io->ci_obj);
-        if (result == 0) {
-                int nonblock = 1;
+        if (result != 0)
+                GOTO(out, result);
 
-restart:
+        cb = descr->cld_mode == CLM_READ ? check_and_discard_cb : pageout_cb;
+        info->clt_fn_index = info->clt_next_index = descr->cld_start;
+        do {
                 cl_2queue_init(queue);
-                cl_page_gang_lookup(env, descr->cld_obj, io, descr->cld_start,
-                                    descr->cld_end, &queue->c2_qin, nonblock);
+                res = cl_page_gang_lookup(env, descr->cld_obj, io,
+                                          info->clt_next_index, descr->cld_end,
+                                          cb, (void *)lock);
                 page_count = queue->c2_qin.pl_nr;
                 if (page_count > 0) {
+                        /* must be writeback case */
+                        LASSERTF(descr->cld_mode >= CLM_WRITE, "lock mode %s\n",
+                                 cl_lock_mode_name(descr->cld_mode));
+
                         result = cl_page_list_unmap(env, io, &queue->c2_qin);
                         if (!discard) {
                                 long timeout = 600; /* 10 minutes. */
@@ -1954,17 +2030,18 @@ restart:
                                         CWARN("Writing %lu pages error: %d\n",
                                               page_count, result);
                         }
-                        cl_lock_page_list_fixup(env, io, lock, &queue->c2_qout);
                         cl_2queue_discard(env, io, queue);
                         cl_2queue_disown(env, io, queue);
+                        cl_2queue_fini(env, queue);
                 }
-                cl_2queue_fini(env, queue);
 
-                if (nonblock) {
-                        nonblock = 0;
-                        goto restart;
-                }
-        }
+                if (info->clt_next_index > descr->cld_end)
+                        break;
+
+                if (res == CLP_GANG_RESCHED)
+                        cfs_cond_resched();
+        } while (res != CLP_GANG_OKAY);
+out:
         cl_io_fini(env, io);
         RETURN(result);
 }
@@ -1992,17 +2069,29 @@ void cl_locks_prune(const struct lu_env *env, struct cl_object *obj, int cancel)
         LASSERT(ergo(!cancel,
                      head->coh_tree.rnode == NULL && head->coh_pages == 0));
 
-        spin_lock(&head->coh_lock_guard);
-        while (!list_empty(&head->coh_locks)) {
+        cfs_spin_lock(&head->coh_lock_guard);
+        while (!cfs_list_empty(&head->coh_locks)) {
                 lock = container_of(head->coh_locks.next,
                                     struct cl_lock, cll_linkage);
                 cl_lock_get_trust(lock);
-                spin_unlock(&head->coh_lock_guard);
+                cfs_spin_unlock(&head->coh_lock_guard);
                 lu_ref_add(&lock->cll_reference, "prune", cfs_current());
+
+again:
                 cl_lock_mutex_get(env, lock);
                 if (lock->cll_state < CLS_FREEING) {
                         LASSERT(lock->cll_holds == 0);
-                        LASSERT(lock->cll_users == 0);
+                        LASSERT(lock->cll_users <= 1);
+                        if (unlikely(lock->cll_users == 1)) {
+                                struct l_wait_info lwi = { 0 };
+
+                                cl_lock_mutex_put(env, lock);
+                                l_wait_event(lock->cll_wq,
+                                             lock->cll_users == 0,
+                                             &lwi);
+                                goto again;
+                        }
+
                         if (cancel)
                                 cl_lock_cancel(env, lock);
                         cl_lock_delete(env, lock);
@@ -2010,27 +2099,13 @@ void cl_locks_prune(const struct lu_env *env, struct cl_object *obj, int cancel)
                 cl_lock_mutex_put(env, lock);
                 lu_ref_del(&lock->cll_reference, "prune", cfs_current());
                 cl_lock_put(env, lock);
-                spin_lock(&head->coh_lock_guard);
+                cfs_spin_lock(&head->coh_lock_guard);
         }
-        spin_unlock(&head->coh_lock_guard);
+        cfs_spin_unlock(&head->coh_lock_guard);
         EXIT;
 }
 EXPORT_SYMBOL(cl_locks_prune);
 
-/**
- * Returns true if \a addr is an address of an allocated cl_lock. Used in
- * assertions. This check is optimistically imprecise, i.e., it occasionally
- * returns true for the incorrect addresses, but if it returns false, then the
- * address is guaranteed to be incorrect. (Should be named cl_lockp().)
- *
- * \see cl_is_page()
- */
-int cl_is_lock(const void *addr)
-{
-        return cfs_mem_is_in_cache(addr, cl_lock_kmem);
-}
-EXPORT_SYMBOL(cl_is_lock);
-
 static struct cl_lock *cl_lock_hold_mutex(const struct lu_env *env,
                                           const struct cl_io *io,
                                           const struct cl_lock_descr *need,
@@ -2089,36 +2164,40 @@ struct cl_lock *cl_lock_request(const struct lu_env *env, struct cl_io *io,
                                 const char *scope, const void *source)
 {
         struct cl_lock       *lock;
-        const struct lu_fid  *fid;
         int                   rc;
-        int                   iter;
         __u32                 enqflags = need->cld_enq_flags;
 
         ENTRY;
-        fid = lu_object_fid(&io->ci_obj->co_lu);
-        iter = 0;
         do {
                 lock = cl_lock_hold_mutex(env, io, need, scope, source);
-                if (!IS_ERR(lock)) {
-                        rc = cl_enqueue_locked(env, lock, io, enqflags);
-                        if (rc == 0) {
-                                if (cl_lock_fits_into(env, lock, need, io)) {
+                if (IS_ERR(lock))
+                        break;
+
+                rc = cl_enqueue_locked(env, lock, io, enqflags);
+                if (rc == 0) {
+                        if (cl_lock_fits_into(env, lock, need, io)) {
+                                if (!(enqflags & CEF_AGL)) {
                                         cl_lock_mutex_put(env, lock);
-                                        cl_lock_lockdep_acquire(env,
-                                                                lock, enqflags);
+                                        cl_lock_lockdep_acquire(env, lock,
+                                                                enqflags);
                                         break;
                                 }
-                                cl_unuse_locked(env, lock);
+                                rc = 1;
                         }
-                        cl_lock_trace(D_DLMTRACE, env, "enqueue failed", lock);
-                        cl_lock_hold_release(env, lock, scope, source);
-                        cl_lock_mutex_put(env, lock);
-                        lu_ref_del(&lock->cll_reference, scope, source);
-                        cl_lock_put(env, lock);
+                        cl_unuse_locked(env, lock);
+                }
+                cl_lock_trace(D_DLMTRACE, env,
+                              rc <= 0 ? "enqueue failed" : "agl succeed", lock);
+                cl_lock_hold_release(env, lock, scope, source);
+                cl_lock_mutex_put(env, lock);
+                lu_ref_del(&lock->cll_reference, scope, source);
+                cl_lock_put(env, lock);
+                if (rc > 0) {
+                        LASSERT(enqflags & CEF_AGL);
+                        lock = NULL;
+                } else if (rc != 0) {
                         lock = ERR_PTR(rc);
-                } else
-                        rc = PTR_ERR(lock);
-                iter++;
+                }
         } while (rc == 0);
         RETURN(lock);
 }
@@ -2188,7 +2267,7 @@ void cl_lock_user_add(const struct lu_env *env, struct cl_lock *lock)
 }
 EXPORT_SYMBOL(cl_lock_user_add);
 
-int cl_lock_user_del(const struct lu_env *env, struct cl_lock *lock)
+void cl_lock_user_del(const struct lu_env *env, struct cl_lock *lock)
 {
         LINVRNT(cl_lock_is_mutexed(lock));
         LINVRNT(cl_lock_invariant(env, lock));
@@ -2196,7 +2275,9 @@ int cl_lock_user_del(const struct lu_env *env, struct cl_lock *lock)
 
         ENTRY;
         cl_lock_used_mod(env, lock, -1);
-        RETURN(lock->cll_users == 0);
+        if (lock->cll_users == 0)
+                cfs_waitq_broadcast(&lock->cll_wq);
+        EXIT;
 }
 EXPORT_SYMBOL(cl_lock_user_del);
 
@@ -2237,13 +2318,13 @@ void cl_lock_print(const struct lu_env *env, void *cookie,
 {
         const struct cl_lock_slice *slice;
         (*printer)(env, cookie, "lock@%p[%d %d %d %d %d %08lx] ",
-                   lock, atomic_read(&lock->cll_ref),
+                   lock, cfs_atomic_read(&lock->cll_ref),
                    lock->cll_state, lock->cll_error, lock->cll_holds,
                    lock->cll_users, lock->cll_flags);
         cl_lock_descr_print(env, cookie, printer, &lock->cll_descr);
         (*printer)(env, cookie, " {\n");
 
-        list_for_each_entry(slice, &lock->cll_layers, cls_linkage) {
+        cfs_list_for_each_entry(slice, &lock->cll_layers, cls_linkage) {
                 (*printer)(env, cookie, "    %s@%p: ",
                            slice->cls_obj->co_lu.lo_dev->ld_type->ldt_name,
                            slice);