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LU-5396 ptlrpc: make some functions static
[fs/lustre-release.git] / lustre / lov / lov_lock.c
index eb17fe7..3166dda 100644 (file)
@@ -1,6 +1,4 @@
-/* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
- * vim:expandtab:shiftwidth=8:tabstop=8:
- *
+/*
  * GPL HEADER START
  *
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  * 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, 2013, Intel Corporation.
  */
 /*
  * This file is part of Lustre, http://www.lustre.org/
 
 #include "lov_cl_internal.h"
 
-/** \addtogroup lov lov @{ */
-
-static struct cl_lock_closure *lov_closure_get(const struct lu_env *env,
-                                               struct cl_lock *parent);
+/** \addtogroup lov
+ *  @{
+ */
 
 /*****************************************************************************
  *
@@ -54,7 +53,7 @@ static struct cl_lock_closure *lov_closure_get(const struct lu_env *env,
  */
 
 static struct lov_sublock_env *lov_sublock_env_get(const struct lu_env *env,
-                                                   struct cl_lock *parent,
+                                                  const struct cl_lock *parent,
                                                    struct lov_lock_sub *lls)
 {
         struct lov_sublock_env *subenv;
@@ -73,12 +72,11 @@ static struct lov_sublock_env *lov_sublock_env_get(const struct lu_env *env,
          * they are not initialized at all. As a temp fix, in this case,
          * we still borrow the parent's env to call sublock operations.
          */
-        if (!cl_object_same(io->ci_obj, parent->cll_descr.cld_obj)) {
+        if (!io || !cl_object_same(io->ci_obj, parent->cll_descr.cld_obj)) {
                 subenv->lse_env = env;
                 subenv->lse_io  = io;
                 subenv->lse_sub = NULL;
         } else {
-                LASSERT(io != NULL);
                 sub = lov_sub_get(env, lio, lls->sub_stripe);
                 if (!IS_ERR(sub)) {
                         subenv->lse_env = sub->sub_env;
@@ -97,184 +95,24 @@ static void lov_sublock_env_put(struct lov_sublock_env *subenv)
                 lov_sub_put(subenv->lse_sub);
 }
 
-static void lov_sublock_adopt(const struct lu_env *env, struct lov_lock *lck,
-                              struct cl_lock *sublock, int idx,
-                              struct lov_lock_link *link)
-{
-        struct lovsub_lock *lsl;
-        struct cl_lock     *parent = lck->lls_cl.cls_lock;
-        int                 rc;
-
-        LASSERT(cl_lock_is_mutexed(parent));
-        LASSERT(cl_lock_is_mutexed(sublock));
-        ENTRY;
-
-        lsl = cl2sub_lock(sublock);
-        /*
-         * check that sub-lock doesn't have lock link to this top-lock.
-         */
-        LASSERT(lov_lock_link_find(env, lck, lsl) == NULL);
-        LASSERT(idx < lck->lls_nr);
-
-        lck->lls_sub[idx].sub_lock = lsl;
-        lck->lls_nr_filled++;
-        LASSERT(lck->lls_nr_filled <= lck->lls_nr);
-        list_add_tail(&link->lll_list, &lsl->lss_parents);
-        link->lll_idx = idx;
-        link->lll_super = lck;
-        cl_lock_get(parent);
-        lu_ref_add(&parent->cll_reference, "lov-child", sublock);
-        lck->lls_sub[idx].sub_flags |= LSF_HELD;
-        cl_lock_user_add(env, sublock);
-
-        rc = lov_sublock_modify(env, lck, lsl, &sublock->cll_descr, idx);
-        LASSERT(rc == 0); /* there is no way this can fail, currently */
-        EXIT;
-}
-
-static struct cl_lock *lov_sublock_alloc(const struct lu_env *env,
-                                         const struct cl_io *io,
-                                         struct lov_lock *lck,
-                                         int idx, struct lov_lock_link **out)
-{
-        struct cl_lock       *sublock;
-        struct cl_lock       *parent;
-        struct lov_lock_link *link;
-
-        LASSERT(idx < lck->lls_nr);
-        ENTRY;
-
-        OBD_SLAB_ALLOC_PTR_GFP(link, lov_lock_link_kmem, CFS_ALLOC_IO);
-        if (link != NULL) {
-                struct lov_sublock_env *subenv;
-                struct lov_lock_sub  *lls;
-                struct cl_lock_descr *descr;
-
-                parent = lck->lls_cl.cls_lock;
-                lls    = &lck->lls_sub[idx];
-                descr  = &lls->sub_descr;
-
-                subenv = lov_sublock_env_get(env, parent, lls);
-                if (!IS_ERR(subenv)) {
-                        /* CAVEAT: Don't try to add a field in lov_lock_sub
-                         * to remember the subio. This is because lock is able
-                         * to be cached, but this is not true for IO. This
-                         * further means a sublock might be referenced in
-                         * different io context. -jay */
-
-                        sublock = cl_lock_hold(subenv->lse_env, subenv->lse_io,
-                                               descr, "lov-parent", parent);
-                        lov_sublock_env_put(subenv);
-                } else {
-                        /* error occurs. */
-                        sublock = (void*)subenv;
-                }
-
-                if (!IS_ERR(sublock))
-                        *out = link;
-                else
-                        OBD_SLAB_FREE_PTR(link, lov_lock_link_kmem);
-        } else
-                sublock = ERR_PTR(-ENOMEM);
-        RETURN(sublock);
-}
-
-static void lov_sublock_unlock(const struct lu_env *env,
-                               struct lovsub_lock *lsl,
-                               struct cl_lock_closure *closure,
-                               struct lov_sublock_env *subenv)
-{
-        ENTRY;
-        lov_sublock_env_put(subenv);
-        lsl->lss_active = NULL;
-        cl_lock_disclosure(env, closure);
-        EXIT;
-}
-
-static int lov_sublock_lock(const struct lu_env *env,
-                            struct lov_lock *lck,
-                            struct lov_lock_sub *lls,
-                            struct cl_lock_closure *closure,
-                            struct lov_sublock_env **lsep)
+static int lov_sublock_init(const struct lu_env *env,
+                           const struct cl_lock *parent,
+                           struct lov_lock_sub *lls)
 {
-        struct lovsub_lock *sublock;
-        struct cl_lock     *child;
-        int                 result = 0;
-        ENTRY;
-
-        LASSERT(list_empty(&closure->clc_list));
-
-        sublock = lls->sub_lock;
-        child = sublock->lss_cl.cls_lock;
-        result = cl_lock_closure_build(env, child, closure);
-        if (result == 0) {
-                struct cl_lock *parent = closure->clc_origin;
-
-                LASSERT(cl_lock_is_mutexed(child));
-                sublock->lss_active = parent;
-
-                if (unlikely(child->cll_state == CLS_FREEING)) {
-                        struct lov_lock_link *link;
-                        /*
-                         * we could race with lock deletion which temporarily
-                         * put the lock in freeing state, bug 19080.
-                         */
-                        LASSERT(!(lls->sub_flags & LSF_HELD));
-
-                        link = lov_lock_link_find(env, lck, sublock);
-                        LASSERT(link != NULL);
-                        lov_lock_unlink(env, link, sublock);
-                        lov_sublock_unlock(env, sublock, closure, NULL);
-                        result = CLO_REPEAT;
-                } else if (lsep) {
-                        struct lov_sublock_env *subenv;
-                        subenv = lov_sublock_env_get(env, parent, lls);
-                        if (IS_ERR(subenv)) {
-                                lov_sublock_unlock(env, sublock,
-                                                   closure, NULL);
-                                result = PTR_ERR(subenv);
-                        } else {
-                                *lsep = subenv;
-                        }
-                }
-        }
-        RETURN(result);
-}
-
-/**
- * Updates the result of a top-lock operation from a result of sub-lock
- * sub-operations. Top-operations like lov_lock_{enqueue,use,unuse}() iterate
- * over sub-locks and lov_subresult() is used to calculate return value of a
- * top-operation. To this end, possible return values of sub-operations are
- * ordered as
- *
- *     - 0                  success
- *     - CLO_WAIT           wait for event
- *     - CLO_REPEAT         repeat top-operation
- *     - -ne                fundamental error
- *
- * Top-level return code can only go down through this list. CLO_REPEAT
- * overwrites CLO_WAIT, because lock mutex was released and sleeping condition
- * has to be rechecked by the upper layer.
- */
-static int lov_subresult(int result, int rc)
-{
-        int result_rank;
-        int rc_rank;
-
-        LASSERT(result <= 0 || result == CLO_REPEAT || result == CLO_WAIT);
-        LASSERT(rc <= 0 || rc == CLO_REPEAT || rc == CLO_WAIT);
-        CLASSERT(CLO_WAIT < CLO_REPEAT);
-
-        ENTRY;
-
-        /* calculate ranks in the ordering above */
-        result_rank = result < 0 ? 1 + CLO_REPEAT : result;
-        rc_rank = rc < 0 ? 1 + CLO_REPEAT : rc;
-
-        if (result_rank < rc_rank)
-                result = rc;
-        RETURN(result);
+       struct lov_sublock_env *subenv;
+       int result;
+       ENTRY;
+
+       subenv = lov_sublock_env_get(env, parent, lls);
+       if (!IS_ERR(subenv)) {
+               result = cl_lock_init(subenv->lse_env, &lls->sub_lock,
+                                     subenv->lse_io);
+               lov_sublock_env_put(subenv);
+       } else {
+               /* error occurs. */
+               result = PTR_ERR(subenv);
+       }
+       RETURN(result);
 }
 
 /**
@@ -285,275 +123,106 @@ static int lov_subresult(int result, int rc)
  * fact that top-lock (that is being created) can be accessed concurrently
  * through already created sub-locks (possibly shared with other top-locks).
  */
-static int lov_lock_sub_init(const struct lu_env *env,
-                             struct lov_lock *lck, const struct cl_io *io)
+static struct lov_lock *lov_lock_sub_init(const struct lu_env *env,
+                                         const struct cl_object *obj,
+                                         struct cl_lock *lock)
 {
         int result = 0;
         int i;
-        int j;
         int nr;
-        int stripe;
-        int start_stripe;
         obd_off start;
         obd_off end;
         obd_off file_start;
         obd_off file_end;
 
-        struct lov_object       *loo    = cl2lov(lck->lls_cl.cls_obj);
-        struct lov_layout_raid0 *r0     = lov_r0(loo);
-        struct cl_lock          *parent = lck->lls_cl.cls_lock;
+       struct lov_object       *loo    = cl2lov(obj);
+       struct lov_layout_raid0 *r0     = lov_r0(loo);
+       struct lov_lock         *lovlck;
 
-        ENTRY;
+       ENTRY;
 
-        lck->lls_orig = parent->cll_descr;
-        file_start = cl_offset(lov2cl(loo), parent->cll_descr.cld_start);
-        file_end   = cl_offset(lov2cl(loo), parent->cll_descr.cld_end + 1) - 1;
+       file_start = cl_offset(lov2cl(loo), lock->cll_descr.cld_start);
+       file_end   = cl_offset(lov2cl(loo), lock->cll_descr.cld_end + 1) - 1;
 
-        start_stripe = lov_stripe_number(r0->lo_lsm, file_start);
         for (i = 0, nr = 0; i < r0->lo_nr; i++) {
                 /*
                  * XXX for wide striping smarter algorithm is desirable,
                  * breaking out of the loop, early.
                  */
-                stripe = (start_stripe + i) % r0->lo_nr;
-                if (lov_stripe_intersects(r0->lo_lsm, stripe,
-                                          file_start, file_end, &start, &end))
-                        nr++;
-        }
-        LASSERT(nr > 0);
-        OBD_ALLOC(lck->lls_sub, nr * sizeof lck->lls_sub[0]);
-        if (lck->lls_sub == NULL)
-                RETURN(-ENOMEM);
-
-        lck->lls_nr = nr;
-        /*
-         * First, fill in sub-lock descriptions in
-         * lck->lls_sub[].sub_descr. They are used by lov_sublock_alloc()
-         * (called below in this function, and by lov_lock_enqueue()) to
-         * create sub-locks. At this moment, no other thread can access
-         * top-lock.
-         */
-        for (j = 0, nr = 0; j < i; ++j) {
-                stripe = (start_stripe + j) % r0->lo_nr;
-                if (lov_stripe_intersects(r0->lo_lsm, stripe,
-                                          file_start, file_end, &start, &end)) {
-                        struct cl_lock_descr *descr;
-
-                        descr = &lck->lls_sub[nr].sub_descr;
-
-                        LASSERT(descr->cld_obj == NULL);
-                        descr->cld_obj   = lovsub2cl(r0->lo_sub[stripe]);
-                        descr->cld_start = cl_index(descr->cld_obj, start);
-                        descr->cld_end   = cl_index(descr->cld_obj, end);
-                        descr->cld_mode  = parent->cll_descr.cld_mode;
-                        descr->cld_gid   = parent->cll_descr.cld_gid;
-                        /* XXX has no effect */
-                        lck->lls_sub[nr].sub_got = *descr;
-                        lck->lls_sub[nr].sub_stripe = stripe;
-                        nr++;
-                }
-        }
-        LASSERT(nr == lck->lls_nr);
-        /*
-         * Then, create sub-locks. Once at least one sub-lock was created,
-         * top-lock can be reached by other threads.
-         */
-        for (i = 0; i < lck->lls_nr; ++i) {
-                struct cl_lock       *sublock;
-                struct lov_lock_link *link;
-
-                if (lck->lls_sub[i].sub_lock == NULL) {
-                        sublock = lov_sublock_alloc(env, io, lck, i, &link);
-                        if (IS_ERR(sublock)) {
-                                result = PTR_ERR(sublock);
-                                break;
-                        }
-                        cl_lock_mutex_get(env, sublock);
-                        cl_lock_mutex_get(env, parent);
-                        /*
-                         * recheck under mutex that sub-lock wasn't created
-                         * concurrently, and that top-lock is still alive.
-                         */
-                        if (lck->lls_sub[i].sub_lock == NULL &&
-                            parent->cll_state < CLS_FREEING) {
-                                lov_sublock_adopt(env, lck, sublock, i, link);
-                                cl_lock_mutex_put(env, parent);
-                        } else {
-                                OBD_SLAB_FREE_PTR(link, lov_lock_link_kmem);
-                                cl_lock_mutex_put(env, parent);
-                                cl_lock_unhold(env, sublock,
-                                               "lov-parent", parent);
-                        }
-                        cl_lock_mutex_put(env, sublock);
-                }
-        }
-        /*
-         * Some sub-locks can be missing at this point. This is not a problem,
-         * because enqueue will create them anyway. Main duty of this function
-         * is to fill in sub-lock descriptions in a race free manner.
-         */
-        RETURN(result);
-}
-
-static int lov_sublock_release(const struct lu_env *env, struct lov_lock *lck,
-                               int i, int deluser, int rc)
-{
-        struct cl_lock *parent = lck->lls_cl.cls_lock;
-
-        LASSERT(cl_lock_is_mutexed(parent));
-        ENTRY;
-
-        if (lck->lls_sub[i].sub_flags & LSF_HELD) {
-                struct cl_lock    *sublock;
-                int dying;
-
-                LASSERT(lck->lls_sub[i].sub_lock != NULL);
-                sublock = lck->lls_sub[i].sub_lock->lss_cl.cls_lock;
-                LASSERT(cl_lock_is_mutexed(sublock));
-
-                lck->lls_sub[i].sub_flags &= ~LSF_HELD;
-                if (deluser)
-                        cl_lock_user_del(env, sublock);
-                /*
-                 * If the last hold is released, and cancellation is pending
-                 * for a sub-lock, release parent mutex, to avoid keeping it
-                 * while sub-lock is being paged out.
-                 */
-                dying = (sublock->cll_descr.cld_mode == CLM_PHANTOM ||
-                         sublock->cll_descr.cld_mode == CLM_GROUP ||
-                         (sublock->cll_flags & (CLF_CANCELPEND|CLF_DOOMED))) &&
-                        sublock->cll_holds == 1;
-                if (dying)
-                        cl_lock_mutex_put(env, parent);
-                cl_lock_unhold(env, sublock, "lov-parent", parent);
-                if (dying) {
-                        cl_lock_mutex_get(env, parent);
-                        rc = lov_subresult(rc, CLO_REPEAT);
-                }
-                /*
-                 * From now on lck->lls_sub[i].sub_lock is a "weak" pointer,
-                 * not backed by a reference on a
-                 * sub-lock. lovsub_lock_delete() will clear
-                 * lck->lls_sub[i].sub_lock under semaphores, just before
-                 * sub-lock is destroyed.
-                 */
-        }
-        RETURN(rc);
-}
-
-static void lov_sublock_hold(const struct lu_env *env, struct lov_lock *lck,
-                             int i)
-{
-        struct cl_lock *parent = lck->lls_cl.cls_lock;
-
-        LASSERT(cl_lock_is_mutexed(parent));
-        ENTRY;
-
-        if (!(lck->lls_sub[i].sub_flags & LSF_HELD)) {
-                struct cl_lock *sublock;
-
-                LASSERT(lck->lls_sub[i].sub_lock != NULL);
-                sublock = lck->lls_sub[i].sub_lock->lss_cl.cls_lock;
-                LASSERT(cl_lock_is_mutexed(sublock));
-                LASSERT(sublock->cll_state != CLS_FREEING);
-
-                lck->lls_sub[i].sub_flags |= LSF_HELD;
-
-                cl_lock_get_trust(sublock);
-                cl_lock_hold_add(env, sublock, "lov-parent", parent);
-                cl_lock_user_add(env, sublock);
-                cl_lock_put(env, sublock);
-        }
-        EXIT;
+               if (likely(r0->lo_sub[i] != NULL) && /* spare layout */
+                   lov_stripe_intersects(loo->lo_lsm, i,
+                                         file_start, file_end, &start, &end))
+                       nr++;
+       }
+       LASSERT(nr > 0);
+
+       OBD_ALLOC_LARGE(lovlck, offsetof(struct lov_lock, lls_sub[nr]));
+       if (lovlck == NULL)
+               RETURN(ERR_PTR(-ENOMEM));
+
+       lovlck->lls_nr = nr;
+       for (i = 0, nr = 0; i < r0->lo_nr; ++i) {
+               if (likely(r0->lo_sub[i] != NULL) &&
+                   lov_stripe_intersects(loo->lo_lsm, i,
+                                         file_start, file_end, &start, &end)) {
+                       struct lov_lock_sub *lls = &lovlck->lls_sub[nr];
+                       struct cl_lock_descr *descr;
+
+                       descr = &lls->sub_lock.cll_descr;
+
+                       LASSERT(descr->cld_obj == NULL);
+                       descr->cld_obj   = lovsub2cl(r0->lo_sub[i]);
+                       descr->cld_start = cl_index(descr->cld_obj, start);
+                       descr->cld_end   = cl_index(descr->cld_obj, end);
+                       descr->cld_mode  = lock->cll_descr.cld_mode;
+                       descr->cld_gid   = lock->cll_descr.cld_gid;
+                       descr->cld_enq_flags = lock->cll_descr.cld_enq_flags;
+
+                       lls->sub_stripe = i;
+
+                       /* initialize sub lock */
+                       result = lov_sublock_init(env, lock, lls);
+                       if (result < 0)
+                               break;
+
+                       lls->sub_initialized = 1;
+                       nr++;
+               }
+       }
+       LASSERT(ergo(result == 0, nr == lovlck->lls_nr));
+
+       if (result != 0) {
+               for (i = 0; i < nr; ++i) {
+                       if (!lovlck->lls_sub[i].sub_initialized)
+                               break;
+
+                       cl_lock_fini(env, &lovlck->lls_sub[i].sub_lock);
+               }
+
+               OBD_FREE_LARGE(lovlck,
+                               offsetof(struct lov_lock, lls_sub[nr]));
+               lovlck = ERR_PTR(result);
+       }
+
+       RETURN(lovlck);
 }
 
 static void lov_lock_fini(const struct lu_env *env,
                           struct cl_lock_slice *slice)
 {
-        struct lov_lock *lck;
-        int i;
-
-        ENTRY;
-        lck = cl2lov_lock(slice);
-        LASSERT(lck->lls_nr_filled == 0);
-        if (lck->lls_sub != NULL) {
-                for (i = 0; i < lck->lls_nr; ++i)
-                        /*
-                         * No sub-locks exists at this point, as sub-lock has
-                         * a reference on its parent.
-                         */
-                        LASSERT(lck->lls_sub[i].sub_lock == NULL);
-                OBD_FREE(lck->lls_sub, lck->lls_nr * sizeof lck->lls_sub[0]);
-        }
-        OBD_SLAB_FREE_PTR(lck, lov_lock_kmem);
-        EXIT;
-}
-
-/**
- * Tries to advance a state machine of a given sub-lock toward enqueuing of
- * the top-lock.
- *
- * \retval 0 if state-transition can proceed
- * \retval -ve otherwise.
- */
-static int lov_lock_enqueue_one(const struct lu_env *env, struct lov_lock *lck,
-                                struct cl_lock *sublock,
-                                struct cl_io *io, __u32 enqflags, int last)
-{
-        int result;
-        ENTRY;
-
-        /* first, try to enqueue a sub-lock ... */
-        result = cl_enqueue_try(env, sublock, io, enqflags);
-        if (sublock->cll_state == CLS_ENQUEUED)
-                /* if it is enqueued, try to `wait' on it---maybe it's already
-                 * granted */
-                result = cl_wait_try(env, sublock);
-        /*
-         * If CEF_ASYNC flag is set, then all sub-locks can be enqueued in
-         * parallel, otherwise---enqueue has to wait until sub-lock is granted
-         * before proceeding to the next one.
-         */
-        if (result == CLO_WAIT && sublock->cll_state <= CLS_HELD &&
-            enqflags & CEF_ASYNC && !last)
-                result = 0;
-        RETURN(result);
-}
-
-/**
- * Helper function for lov_lock_enqueue() that creates missing sub-lock.
- */
-static int lov_sublock_fill(const struct lu_env *env, struct cl_lock *parent,
-                            struct cl_io *io, struct lov_lock *lck, int idx)
-{
-        struct lov_lock_link *link;
-        struct cl_lock       *sublock;
-        int                   result;
-
-        LASSERT(parent->cll_depth == 1);
-        cl_lock_mutex_put(env, parent);
-        sublock = lov_sublock_alloc(env, io, lck, idx, &link);
-        if (!IS_ERR(sublock))
-                cl_lock_mutex_get(env, sublock);
-        cl_lock_mutex_get(env, parent);
-
-        if (!IS_ERR(sublock)) {
-                if (parent->cll_state == CLS_QUEUING &&
-                    lck->lls_sub[idx].sub_lock == NULL)
-                        lov_sublock_adopt(env, lck, sublock, idx, link);
-                else {
-                        OBD_SLAB_FREE_PTR(link, lov_lock_link_kmem);
-                        /* other thread allocated sub-lock, or enqueue is no
-                         * longer going on */
-                        cl_lock_mutex_put(env, parent);
-                        cl_lock_unhold(env, sublock, "lov-parent", parent);
-                        cl_lock_mutex_get(env, parent);
-                }
-                cl_lock_mutex_put(env, sublock);
-                result = CLO_REPEAT;
-        } else
-                result = PTR_ERR(sublock);
-        return result;
+       struct lov_lock *lovlck;
+       int i;
+
+       ENTRY;
+       lovlck = cl2lov_lock(slice);
+       for (i = 0; i < lovlck->lls_nr; ++i) {
+               LASSERT(!lovlck->lls_sub[i].sub_is_enqueued);
+               if (lovlck->lls_sub[i].sub_initialized)
+                       cl_lock_fini(env, &lovlck->lls_sub[i].sub_lock);
+       }
+       OBD_FREE_LARGE(lovlck,
+                      offsetof(struct lov_lock, lls_sub[lovlck->lls_nr]));
+       EXIT;
 }
 
 /**
@@ -564,452 +233,65 @@ static int lov_sublock_fill(const struct lu_env *env, struct cl_lock *parent,
  * and concurrent sub-lock cancellations.
  */
 static int lov_lock_enqueue(const struct lu_env *env,
-                            const struct cl_lock_slice *slice,
-                            struct cl_io *io, __u32 enqflags)
+                           const struct cl_lock_slice *slice,
+                           struct cl_io *io, struct cl_sync_io *anchor)
 {
-        struct cl_lock         *lock    = slice->cls_lock;
-        struct lov_lock        *lck     = cl2lov_lock(slice);
-        struct cl_lock_closure *closure = lov_closure_get(env, lock);
-        int i;
-        int result;
-        enum cl_lock_state minstate;
-
-        ENTRY;
-
-        for (result = 0, minstate = CLS_FREEING, i = 0; i < lck->lls_nr; ++i) {
-                int rc;
-                struct lovsub_lock     *sub;
-                struct lov_lock_sub    *lls;
-                struct cl_lock         *sublock;
-                struct lov_sublock_env *subenv;
-
-                if (lock->cll_state != CLS_QUEUING) {
-                        /*
-                         * Lock might have left QUEUING state if previous
-                         * iteration released its mutex. Stop enqueing in this
-                         * case and let the upper layer to decide what to do.
-                         */
-                        LASSERT(i > 0 && result != 0);
-                        break;
-                }
-
-                lls = &lck->lls_sub[i];
-                sub = lls->sub_lock;
-                /*
-                 * Sub-lock might have been canceled, while top-lock was
-                 * cached.
-                 */
-                if (sub == NULL) {
-                        result = lov_sublock_fill(env, lock, io, lck, i);
-                        /* lov_sublock_fill() released @lock mutex,
-                         * restart. */
-                        break;
-                }
-                sublock = sub->lss_cl.cls_lock;
-                rc = lov_sublock_lock(env, lck, lls, closure, &subenv);
-                if (rc == 0) {
-                        lov_sublock_hold(env, lck, i);
-                        rc = lov_lock_enqueue_one(subenv->lse_env, lck, sublock,
-                                                  subenv->lse_io, enqflags,
-                                                  i == lck->lls_nr - 1);
-                        minstate = min(minstate, sublock->cll_state);
-                        /*
-                         * Don't hold a sub-lock in CLS_CACHED state, see
-                         * description for lov_lock::lls_sub.
-                         */
-                        if (sublock->cll_state > CLS_HELD)
-                                rc = lov_sublock_release(env, lck, i, 1, rc);
-                        lov_sublock_unlock(env, sub, closure, subenv);
-                }
-                result = lov_subresult(result, rc);
-                if (result < 0)
-                        break;
-        }
-        cl_lock_closure_fini(closure);
-        RETURN(result ?: minstate >= CLS_ENQUEUED ? 0 : CLO_WAIT);
-}
-
-static int lov_lock_unuse(const struct lu_env *env,
-                          const struct cl_lock_slice *slice)
-{
-        struct lov_lock        *lck     = cl2lov_lock(slice);
-        struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
-        int i;
-        int result;
-
-        ENTRY;
-
-        for (result = 0, i = 0; i < lck->lls_nr; ++i) {
-                int rc;
-                struct lovsub_lock     *sub;
-                struct cl_lock         *sublock;
-                struct lov_lock_sub    *lls;
-                struct lov_sublock_env *subenv;
-
-                /* top-lock state cannot change concurrently, because single
-                 * thread (one that released the last hold) carries unlocking
-                 * to the completion. */
-                LASSERT(slice->cls_lock->cll_state == CLS_UNLOCKING);
-                lls = &lck->lls_sub[i];
-                sub = lls->sub_lock;
-                if (sub == NULL)
-                        continue;
-
-                sublock = sub->lss_cl.cls_lock;
-                rc = lov_sublock_lock(env, lck, lls, closure, &subenv);
-                if (rc == 0) {
-                        if (lck->lls_sub[i].sub_flags & LSF_HELD) {
-                                LASSERT(sublock->cll_state == CLS_HELD);
-                                rc = cl_unuse_try(subenv->lse_env, sublock);
-                                if (rc != CLO_WAIT)
-                                        rc = lov_sublock_release(env, lck,
-                                                                 i, 0, rc);
-                        }
-                        lov_sublock_unlock(env, sub, closure, subenv);
-                }
-                result = lov_subresult(result, rc);
-                if (result < 0)
-                        break;
-        }
-        if (result == 0 && lck->lls_unuse_race) {
-                lck->lls_unuse_race = 0;
-                result = -ESTALE;
-        }
-        cl_lock_closure_fini(closure);
-        RETURN(result);
-}
-
-static int lov_lock_wait(const struct lu_env *env,
-                         const struct cl_lock_slice *slice)
-{
-        struct lov_lock        *lck     = cl2lov_lock(slice);
-        struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
-        enum cl_lock_state      minstate;
-        int                     result;
-        int                     i;
-
-        ENTRY;
-
-        for (result = 0, minstate = CLS_FREEING, i = 0; i < lck->lls_nr; ++i) {
-                int rc;
-                struct lovsub_lock     *sub;
-                struct cl_lock         *sublock;
-                struct lov_lock_sub    *lls;
-                struct lov_sublock_env *subenv;
-
-                lls = &lck->lls_sub[i];
-                sub = lls->sub_lock;
-                LASSERT(sub != NULL);
-                sublock = sub->lss_cl.cls_lock;
-                rc = lov_sublock_lock(env, lck, lls, closure, &subenv);
-                if (rc == 0) {
-                        LASSERT(sublock->cll_state >= CLS_ENQUEUED);
-                        if (sublock->cll_state < CLS_HELD)
-                                rc = cl_wait_try(env, sublock);
-
-                        minstate = min(minstate, sublock->cll_state);
-                        lov_sublock_unlock(env, sub, closure, subenv);
-                }
-                result = lov_subresult(result, rc);
-                if (result < 0)
-                        break;
-        }
-        cl_lock_closure_fini(closure);
-        RETURN(result ?: minstate >= CLS_HELD ? 0 : CLO_WAIT);
+       struct cl_lock          *lock   = slice->cls_lock;
+       struct lov_lock         *lovlck = cl2lov_lock(slice);
+       int                     i;
+       int                     rc      = 0;
+
+       ENTRY;
+
+       for (i = 0; i < lovlck->lls_nr; ++i) {
+               struct lov_lock_sub     *lls = &lovlck->lls_sub[i];
+               struct lov_sublock_env  *subenv;
+
+               subenv = lov_sublock_env_get(env, lock, lls);
+               if (IS_ERR(subenv)) {
+                       rc = PTR_ERR(subenv);
+                       break;
+               }
+
+               rc = cl_lock_enqueue(subenv->lse_env, subenv->lse_io,
+                                    &lls->sub_lock, anchor);
+               lov_sublock_env_put(subenv);
+               if (rc != 0)
+                       break;
+
+               lls->sub_is_enqueued = 1;
+       }
+       RETURN(rc);
 }
 
-static int lov_lock_use(const struct lu_env *env,
-                        const struct cl_lock_slice *slice)
+static void lov_lock_cancel(const struct lu_env *env,
+                           const struct cl_lock_slice *slice)
 {
-        struct lov_lock        *lck     = cl2lov_lock(slice);
-        struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
-        int                     result;
-        int                     i;
-
-        LASSERT(slice->cls_lock->cll_state == CLS_CACHED);
-        ENTRY;
-
-        for (result = 0, i = 0; i < lck->lls_nr; ++i) {
-                int rc;
-                struct lovsub_lock     *sub;
-                struct cl_lock         *sublock;
-                struct lov_lock_sub    *lls;
-                struct lov_sublock_env *subenv;
-
-                if (slice->cls_lock->cll_state != CLS_CACHED) {
-                        /* see comment in lov_lock_enqueue(). */
-                        LASSERT(i > 0 && result != 0);
-                        break;
-                }
-                /*
-                 * if a sub-lock was destroyed while top-lock was in
-                 * CLS_CACHED state, top-lock would have been moved into
-                 * CLS_NEW state, so all sub-locks have to be in place.
-                 */
-                lls = &lck->lls_sub[i];
-                sub = lls->sub_lock;
-                LASSERT(sub != NULL);
-                sublock = sub->lss_cl.cls_lock;
-                rc = lov_sublock_lock(env, lck, lls, closure, &subenv);
-                if (rc == 0) {
-                        LASSERT(sublock->cll_state != CLS_FREEING);
-                        lov_sublock_hold(env, lck, i);
-                        if (sublock->cll_state == CLS_CACHED) {
-                                rc = cl_use_try(subenv->lse_env, sublock);
-                                if (rc != 0)
-                                        rc = lov_sublock_release(env, lck,
-                                                                 i, 1, rc);
-                        } else
-                                rc = 0;
-                        lov_sublock_unlock(env, sub, closure, subenv);
-                }
-                result = lov_subresult(result, rc);
-                if (result < 0)
-                        break;
-        }
-        cl_lock_closure_fini(closure);
-        RETURN(result);
-}
-
-#if 0
-static int lock_lock_multi_match()
-{
-        struct cl_lock          *lock    = slice->cls_lock;
-        struct cl_lock_descr    *subneed = &lov_env_info(env)->lti_ldescr;
-        struct lov_object       *loo     = cl2lov(lov->lls_cl.cls_obj);
-        struct lov_layout_raid0 *r0      = lov_r0(loo);
-        struct lov_lock_sub     *sub;
-        struct cl_object        *subobj;
-        obd_off  fstart;
-        obd_off  fend;
-        obd_off  start;
-        obd_off  end;
-        int i;
-
-        fstart = cl_offset(need->cld_obj, need->cld_start);
-        fend   = cl_offset(need->cld_obj, need->cld_end + 1) - 1;
-        subneed->cld_mode = need->cld_mode;
-        cl_lock_mutex_get(env, lock);
-        for (i = 0; i < lov->lls_nr; ++i) {
-                sub = &lov->lls_sub[i];
-                if (sub->sub_lock == NULL)
-                        continue;
-                subobj = sub->sub_descr.cld_obj;
-                if (!lov_stripe_intersects(r0->lo_lsm, sub->sub_stripe,
-                                           fstart, fend, &start, &end))
-                        continue;
-                subneed->cld_start = cl_index(subobj, start);
-                subneed->cld_end   = cl_index(subobj, end);
-                subneed->cld_obj   = subobj;
-                if (!cl_lock_ext_match(&sub->sub_got, subneed)) {
-                        result = 0;
-                        break;
-                }
-        }
-        cl_lock_mutex_put(env, lock);
-}
-#endif
-
-/**
- * Check if the extent region \a descr is covered by \a child against the
- * specific \a stripe.
- */
-static int lov_lock_stripe_is_matching(const struct lu_env *env,
-                                       struct lov_object *lov, int stripe,
-                                       const struct cl_lock_descr *child,
-                                       const struct cl_lock_descr *descr)
-{
-        struct lov_stripe_md *lsm = lov_r0(lov)->lo_lsm;
-        obd_off start;
-        obd_off end;
-        int result;
-
-        if (lov_r0(lov)->lo_nr == 1)
-                return cl_lock_ext_match(child, descr);
-
-        /*
-         * For a multi-stripes object:
-         * - make sure the descr only covers child's stripe, and
-         * - check if extent is matching.
-         */
-        start = cl_offset(&lov->lo_cl, descr->cld_start);
-        end   = cl_offset(&lov->lo_cl, descr->cld_end + 1) - 1;
-        result = end - start <= lsm->lsm_stripe_size &&
-                 stripe == lov_stripe_number(lsm, start) &&
-                 stripe == lov_stripe_number(lsm, end);
-        if (result) {
-                struct cl_lock_descr *subd = &lov_env_info(env)->lti_ldescr;
-                obd_off sub_start;
-                obd_off sub_end;
-
-                subd->cld_obj  = NULL;   /* don't need sub object at all */
-                subd->cld_mode = descr->cld_mode;
-                subd->cld_gid  = descr->cld_gid;
-                result = lov_stripe_intersects(lsm, stripe, start, end,
-                                               &sub_start, &sub_end);
-                LASSERT(result);
-                subd->cld_start = cl_index(child->cld_obj, sub_start);
-                subd->cld_end   = cl_index(child->cld_obj, sub_end);
-                result = cl_lock_ext_match(child, subd);
-        }
-        return result;
-}
-
-/**
- * An implementation of cl_lock_operations::clo_fits_into() method.
- *
- * Checks whether a lock (given by \a slice) is suitable for \a
- * io. Multi-stripe locks can be used only for "quick" io, like truncate, or
- * O_APPEND write.
- *
- * \see ccc_lock_fits_into().
- */
-static int lov_lock_fits_into(const struct lu_env *env,
-                              const struct cl_lock_slice *slice,
-                              const struct cl_lock_descr *need,
-                              const struct cl_io *io)
-{
-        struct lov_lock   *lov = cl2lov_lock(slice);
-        struct lov_object *obj = cl2lov(slice->cls_obj);
-        int result;
-
-        LASSERT(cl_object_same(need->cld_obj, slice->cls_obj));
-        LASSERT(lov->lls_nr > 0);
-
-        ENTRY;
-
-        if (need->cld_mode == CLM_GROUP)
-                /*
-                 * always allow to match group lock.
-                 */
-                result = cl_lock_ext_match(&lov->lls_orig, need);
-        else if (lov->lls_nr == 1) {
-                struct cl_lock_descr *got = &lov->lls_sub[0].sub_got;
-                result = lov_lock_stripe_is_matching(env,
-                                                     cl2lov(slice->cls_obj),
-                                                     lov->lls_sub[0].sub_stripe,
-                                                     got, need);
-        } else if (io->ci_type != CIT_TRUNC && io->ci_type != CIT_MISC &&
-                   !cl_io_is_append(io) && need->cld_mode != CLM_PHANTOM)
-                /*
-                 * Multi-stripe locks are only suitable for `quick' IO and for
-                 * glimpse.
-                 */
-                result = 0;
-        else
-                /*
-                 * Most general case: multi-stripe existing lock, and
-                 * (potentially) multi-stripe @need lock. Check that @need is
-                 * covered by @lov's sub-locks.
-                 *
-                 * For now, ignore lock expansions made by the server, and
-                 * match against original lock extent.
-                 */
-                result = cl_lock_ext_match(&lov->lls_orig, need);
-        CDEBUG(D_DLMTRACE, DDESCR"/"DDESCR" %i %i/%i: %i\n",
-               PDESCR(&lov->lls_orig), PDESCR(&lov->lls_sub[0].sub_got),
-               lov->lls_sub[0].sub_stripe, lov->lls_nr, lov_r0(obj)->lo_nr,
-               result);
-        RETURN(result);
-}
-
-void lov_lock_unlink(const struct lu_env *env,
-                     struct lov_lock_link *link, struct lovsub_lock *sub)
-{
-        struct lov_lock *lck    = link->lll_super;
-        struct cl_lock  *parent = lck->lls_cl.cls_lock;
-
-        LASSERT(cl_lock_is_mutexed(parent));
-        LASSERT(cl_lock_is_mutexed(sub->lss_cl.cls_lock));
-        ENTRY;
-
-        list_del_init(&link->lll_list);
-        LASSERT(lck->lls_sub[link->lll_idx].sub_lock == sub);
-        /* yank this sub-lock from parent's array */
-        lck->lls_sub[link->lll_idx].sub_lock = NULL;
-        LASSERT(lck->lls_nr_filled > 0);
-        lck->lls_nr_filled--;
-        lu_ref_del(&parent->cll_reference, "lov-child", sub->lss_cl.cls_lock);
-        cl_lock_put(env, parent);
-        OBD_SLAB_FREE_PTR(link, lov_lock_link_kmem);
-        EXIT;
-}
-
-struct lov_lock_link *lov_lock_link_find(const struct lu_env *env,
-                                         struct lov_lock *lck,
-                                         struct lovsub_lock *sub)
-{
-        struct lov_lock_link *scan;
-
-        LASSERT(cl_lock_is_mutexed(sub->lss_cl.cls_lock));
-        ENTRY;
-
-        list_for_each_entry(scan, &sub->lss_parents, lll_list) {
-                if (scan->lll_super == lck)
-                        RETURN(scan);
-        }
-        RETURN(NULL);
-}
-
-/**
- * An implementation of cl_lock_operations::clo_delete() method. This is
- * invoked for "top-to-bottom" delete, when lock destruction starts from the
- * top-lock, e.g., as a result of inode destruction.
- *
- * Unlinks top-lock from all its sub-locks. Sub-locks are not deleted there:
- * this is done separately elsewhere:
- *
- *     - for inode destruction, lov_object_delete() calls cl_object_kill() for
- *       each sub-object, purging its locks;
- *
- *     - in other cases (e.g., a fatal error with a top-lock) sub-locks are
- *       left in the cache.
- */
-static void lov_lock_delete(const struct lu_env *env,
-                            const struct cl_lock_slice *slice)
-{
-        struct lov_lock        *lck     = cl2lov_lock(slice);
-        struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
-        int i;
-
-        LASSERT(slice->cls_lock->cll_state == CLS_FREEING);
-        ENTRY;
-
-        for (i = 0; i < lck->lls_nr; ++i) {
-                struct lov_lock_sub *lls;
-                struct lovsub_lock  *lsl;
-                struct cl_lock      *sublock;
-                int rc;
-
-                lls = &lck->lls_sub[i];
-                lsl = lls->sub_lock;
-                if (lsl == NULL)
-                        continue;
-
-                sublock = lsl->lss_cl.cls_lock;
-                rc = lov_sublock_lock(env, lck, lls, closure, NULL);
-                if (rc == 0) {
-                        if (lck->lls_sub[i].sub_flags & LSF_HELD)
-                                lov_sublock_release(env, lck, i, 1, 0);
-                        if (sublock->cll_state < CLS_FREEING) {
-                                struct lov_lock_link *link;
-
-                                link = lov_lock_link_find(env, lck, lsl);
-                                LASSERT(link != NULL);
-                                lov_lock_unlink(env, link, lsl);
-                                LASSERT(lck->lls_sub[i].sub_lock == NULL);
-                        }
-                        lov_sublock_unlock(env, lsl, closure, NULL);
-                } else if (rc == CLO_REPEAT) {
-                        --i; /* repeat with this lock */
-                } else {
-                        CL_LOCK_DEBUG(D_ERROR, env, sublock,
-                                      "Cannot get sub-lock for delete: %i\n",
-                                      rc);
-                }
-        }
-        cl_lock_closure_fini(closure);
-        EXIT;
+       struct cl_lock  *lock   = slice->cls_lock;
+       struct lov_lock *lovlck = cl2lov_lock(slice);
+       int i;
+
+       ENTRY;
+
+       for (i = 0; i < lovlck->lls_nr; ++i) {
+               struct lov_lock_sub     *lls = &lovlck->lls_sub[i];
+               struct cl_lock          *sublock = &lls->sub_lock;
+               struct lov_sublock_env  *subenv;
+
+               if (!lls->sub_is_enqueued)
+                       continue;
+
+               lls->sub_is_enqueued = 0;
+               subenv = lov_sublock_env_get(env, lock, lls);
+               if (!IS_ERR(subenv)) {
+                       cl_lock_cancel(subenv->lse_env, sublock);
+                       lov_sublock_env_put(subenv);
+               } else {
+                       CL_LOCK_DEBUG(D_ERROR, env, slice->cls_lock,
+                                     "lov_lock_cancel fails with %ld.\n",
+                                     PTR_ERR(subenv));
+               }
+       }
 }
 
 static int lov_lock_print(const struct lu_env *env, void *cookie,
@@ -1023,12 +305,8 @@ static int lov_lock_print(const struct lu_env *env, void *cookie,
                 struct lov_lock_sub *sub;
 
                 sub = &lck->lls_sub[i];
-                (*p)(env, cookie, "    %d %x: ", i, sub->sub_flags);
-                if (sub->sub_lock != NULL)
-                        cl_lock_print(env, cookie, p,
-                                      sub->sub_lock->lss_cl.cls_lock);
-                else
-                        (*p)(env, cookie, "---\n");
+               (*p)(env, cookie, "    %d %x: ", i, sub->sub_is_enqueued);
+               cl_lock_print(env, cookie, p, &sub->sub_lock);
         }
         return 0;
 }
@@ -1036,40 +314,58 @@ static int lov_lock_print(const struct lu_env *env, void *cookie,
 static const struct cl_lock_operations lov_lock_ops = {
         .clo_fini      = lov_lock_fini,
         .clo_enqueue   = lov_lock_enqueue,
-        .clo_wait      = lov_lock_wait,
-        .clo_use       = lov_lock_use,
-        .clo_unuse     = lov_lock_unuse,
-        .clo_fits_into = lov_lock_fits_into,
-        .clo_delete    = lov_lock_delete,
+        .clo_cancel    = lov_lock_cancel,
         .clo_print     = lov_lock_print
 };
 
 int lov_lock_init_raid0(const struct lu_env *env, struct cl_object *obj,
-                        struct cl_lock *lock, const struct cl_io *io)
+                       struct cl_lock *lock, const struct cl_io *io)
 {
-        struct lov_lock *lck;
-        int result;
-
-        ENTRY;
-        OBD_SLAB_ALLOC_PTR_GFP(lck, lov_lock_kmem, CFS_ALLOC_IO);
-        if (lck != NULL) {
-                cl_lock_slice_add(lock, &lck->lls_cl, obj, &lov_lock_ops);
-                result = lov_lock_sub_init(env, lck, io);
-        } else
-                result = -ENOMEM;
-        RETURN(result);
+       struct lov_lock *lck;
+       int result = 0;
+
+       ENTRY;
+       lck = lov_lock_sub_init(env, obj, lock);
+       if (!IS_ERR(lck))
+               cl_lock_slice_add(lock, &lck->lls_cl, obj, &lov_lock_ops);
+       else
+               result = PTR_ERR(lck);
+       RETURN(result);
 }
 
-static struct cl_lock_closure *lov_closure_get(const struct lu_env *env,
-                                               struct cl_lock *parent)
+static void lov_empty_lock_fini(const struct lu_env *env,
+                               struct cl_lock_slice *slice)
 {
-        struct cl_lock_closure *closure;
+       struct lov_lock *lck = cl2lov_lock(slice);
+       OBD_SLAB_FREE_PTR(lck, lov_lock_kmem);
+}
 
-        closure = &lov_env_info(env)->lti_closure;
-        LASSERT(list_empty(&closure->clc_list));
-        cl_lock_closure_init(env, closure, parent, 1);
-        return closure;
+static int lov_empty_lock_print(const struct lu_env *env, void *cookie,
+                       lu_printer_t p, const struct cl_lock_slice *slice)
+{
+       (*p)(env, cookie, "empty\n");
+       return 0;
 }
 
+/* XXX: more methods will be added later. */
+static const struct cl_lock_operations lov_empty_lock_ops = {
+       .clo_fini  = lov_empty_lock_fini,
+       .clo_print = lov_empty_lock_print
+};
+
+int lov_lock_init_empty(const struct lu_env *env, struct cl_object *obj,
+                       struct cl_lock *lock, const struct cl_io *io)
+{
+       struct lov_lock *lck;
+       int result = -ENOMEM;
+
+       ENTRY;
+       OBD_SLAB_ALLOC_PTR_GFP(lck, lov_lock_kmem, GFP_NOFS);
+       if (lck != NULL) {
+               cl_lock_slice_add(lock, &lck->lls_cl, obj, &lov_empty_lock_ops);
+               result = 0;
+       }
+       RETURN(result);
+}
 
 /** @} lov */