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LU-6271 osc: handle osc eviction correctly
[fs/lustre-release.git] / lustre / osc / osc_cache.c
index 1096d03..dd28035 100644 (file)
@@ -27,7 +27,7 @@
  * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  * Use is subject to license terms.
  *
- * Copyright (c) 2012, 2013, Intel Corporation.
+ * Copyright (c) 2012, 2014, Intel Corporation.
  *
  */
 /*
@@ -48,7 +48,7 @@ static int extent_debug; /* set it to be true for more debug */
 
 static void osc_update_pending(struct osc_object *obj, int cmd, int delta);
 static int osc_extent_wait(const struct lu_env *env, struct osc_extent *ext,
-                          int state);
+                          enum osc_extent_state state);
 static void osc_ap_completion(const struct lu_env *env, struct client_obd *cli,
                              struct osc_async_page *oap, int sent, int rc);
 static int osc_make_ready(const struct lu_env *env, struct osc_async_page *oap,
@@ -76,6 +76,8 @@ static inline char *ext_flags(struct osc_extent *ext, char *flags)
        *buf++ = ext->oe_rw ? 'r' : 'w';
        if (ext->oe_intree)
                *buf++ = 'i';
+       if (ext->oe_sync)
+               *buf++ = 'S';
        if (ext->oe_srvlock)
                *buf++ = 's';
        if (ext->oe_hp)
@@ -92,9 +94,9 @@ static inline char *ext_flags(struct osc_extent *ext, char *flags)
        return flags;
 }
 
-static inline char list_empty_marker(cfs_list_t *list)
+static inline char list_empty_marker(struct list_head *list)
 {
-       return cfs_list_empty(list) ? '-' : '+';
+       return list_empty(list) ? '-' : '+';
 }
 
 #define EXTSTR       "[%lu -> %lu/%lu]"
@@ -112,8 +114,8 @@ static const char *oes_strings[] = {
                /* ----- extent part 0 ----- */                               \
                __ext, EXTPARA(__ext),                                        \
                /* ----- part 1 ----- */                                      \
-               cfs_atomic_read(&__ext->oe_refc),                             \
-               cfs_atomic_read(&__ext->oe_users),                            \
+               atomic_read(&__ext->oe_refc),                         \
+               atomic_read(&__ext->oe_users),                        \
                list_empty_marker(&__ext->oe_link),                           \
                oes_strings[__ext->oe_state], ext_flags(__ext, __buf),        \
                __ext->oe_obj,                                                \
@@ -121,9 +123,13 @@ static const char *oes_strings[] = {
                __ext->oe_grants, __ext->oe_nr_pages,                         \
                list_empty_marker(&__ext->oe_pages),                          \
                waitqueue_active(&__ext->oe_waitq) ? '+' : '-',               \
-               __ext->oe_osclock, __ext->oe_mppr, __ext->oe_owner,           \
+               __ext->oe_dlmlock, __ext->oe_mppr, __ext->oe_owner,           \
                /* ----- part 4 ----- */                                      \
                ## __VA_ARGS__);                                              \
+       if (lvl == D_ERROR && __ext->oe_dlmlock != NULL)                      \
+               LDLM_ERROR(__ext->oe_dlmlock, "extent: %p\n", __ext);         \
+       else                                                                  \
+               LDLM_DEBUG(__ext->oe_dlmlock, "extent: %p\n", __ext);         \
 } while (0)
 
 #undef EASSERTF
@@ -175,7 +181,7 @@ static int osc_extent_sanity_check0(struct osc_extent *ext,
 {
        struct osc_object *obj = ext->oe_obj;
        struct osc_async_page *oap;
-       int page_count;
+       size_t page_count;
        int rc = 0;
 
        if (!osc_object_is_locked(obj))
@@ -184,20 +190,20 @@ static int osc_extent_sanity_check0(struct osc_extent *ext,
        if (ext->oe_state >= OES_STATE_MAX)
                GOTO(out, rc = 10);
 
-       if (cfs_atomic_read(&ext->oe_refc) <= 0)
+       if (atomic_read(&ext->oe_refc) <= 0)
                GOTO(out, rc = 20);
 
-       if (cfs_atomic_read(&ext->oe_refc) < cfs_atomic_read(&ext->oe_users))
+       if (atomic_read(&ext->oe_refc) < atomic_read(&ext->oe_users))
                GOTO(out, rc = 30);
 
        switch (ext->oe_state) {
        case OES_INV:
-               if (ext->oe_nr_pages > 0 || !cfs_list_empty(&ext->oe_pages))
+               if (ext->oe_nr_pages > 0 || !list_empty(&ext->oe_pages))
                        GOTO(out, rc = 35);
                GOTO(out, rc = 0);
                break;
        case OES_ACTIVE:
-               if (cfs_atomic_read(&ext->oe_users) == 0)
+               if (atomic_read(&ext->oe_users) == 0)
                        GOTO(out, rc = 40);
                if (ext->oe_hp)
                        GOTO(out, rc = 50);
@@ -210,22 +216,26 @@ static int osc_extent_sanity_check0(struct osc_extent *ext,
                if (ext->oe_fsync_wait && !ext->oe_urgent && !ext->oe_hp)
                        GOTO(out, rc = 65);
        default:
-               if (cfs_atomic_read(&ext->oe_users) > 0)
+               if (atomic_read(&ext->oe_users) > 0)
                        GOTO(out, rc = 70);
        }
 
        if (ext->oe_max_end < ext->oe_end || ext->oe_end < ext->oe_start)
                GOTO(out, rc = 80);
 
-       if (ext->oe_osclock == NULL && ext->oe_grants > 0)
+       if (ext->oe_sync && ext->oe_grants > 0)
                GOTO(out, rc = 90);
 
-       if (ext->oe_osclock) {
-               struct cl_lock_descr *descr;
-               descr = &ext->oe_osclock->cll_descr;
-               if (!(descr->cld_start <= ext->oe_start &&
-                     descr->cld_end >= ext->oe_max_end))
+       if (ext->oe_dlmlock != NULL && !ldlm_is_failed(ext->oe_dlmlock)) {
+               struct ldlm_extent *extent;
+
+               extent = &ext->oe_dlmlock->l_policy_data.l_extent;
+               if (!(extent->start <= cl_offset(osc2cl(obj), ext->oe_start) &&
+                     extent->end   >= cl_offset(osc2cl(obj), ext->oe_max_end)))
                        GOTO(out, rc = 100);
+
+               if (!(ext->oe_dlmlock->l_granted_mode & (LCK_PW | LCK_GROUP)))
+                       GOTO(out, rc = 102);
        }
 
        if (ext->oe_nr_pages > ext->oe_mppr)
@@ -240,8 +250,8 @@ static int osc_extent_sanity_check0(struct osc_extent *ext,
                GOTO(out, rc = 0);
 
        page_count = 0;
-       cfs_list_for_each_entry(oap, &ext->oe_pages, oap_pending_item) {
-               pgoff_t index = oap2cl_page(oap)->cp_index;
+       list_for_each_entry(oap, &ext->oe_pages, oap_pending_item) {
+               pgoff_t index = osc_index(oap2osc(oap));
                ++page_count;
                if (index > ext->oe_end || index < ext->oe_start)
                        GOTO(out, rc = 110);
@@ -315,13 +325,13 @@ static struct osc_extent *osc_extent_alloc(struct osc_object *obj)
 
        RB_CLEAR_NODE(&ext->oe_node);
        ext->oe_obj = obj;
-       cfs_atomic_set(&ext->oe_refc, 1);
-       cfs_atomic_set(&ext->oe_users, 0);
-       CFS_INIT_LIST_HEAD(&ext->oe_link);
+       atomic_set(&ext->oe_refc, 1);
+       atomic_set(&ext->oe_users, 0);
+       INIT_LIST_HEAD(&ext->oe_link);
        ext->oe_state = OES_INV;
-       CFS_INIT_LIST_HEAD(&ext->oe_pages);
+       INIT_LIST_HEAD(&ext->oe_pages);
        init_waitqueue_head(&ext->oe_waitq);
-       ext->oe_osclock = NULL;
+       ext->oe_dlmlock = NULL;
 
        return ext;
 }
@@ -333,23 +343,25 @@ static void osc_extent_free(struct osc_extent *ext)
 
 static struct osc_extent *osc_extent_get(struct osc_extent *ext)
 {
-       LASSERT(cfs_atomic_read(&ext->oe_refc) >= 0);
-       cfs_atomic_inc(&ext->oe_refc);
+       LASSERT(atomic_read(&ext->oe_refc) >= 0);
+       atomic_inc(&ext->oe_refc);
        return ext;
 }
 
 static void osc_extent_put(const struct lu_env *env, struct osc_extent *ext)
 {
-       LASSERT(cfs_atomic_read(&ext->oe_refc) > 0);
-       if (cfs_atomic_dec_and_test(&ext->oe_refc)) {
-               LASSERT(cfs_list_empty(&ext->oe_link));
-               LASSERT(cfs_atomic_read(&ext->oe_users) == 0);
+       LASSERT(atomic_read(&ext->oe_refc) > 0);
+       if (atomic_dec_and_test(&ext->oe_refc)) {
+               LASSERT(list_empty(&ext->oe_link));
+               LASSERT(atomic_read(&ext->oe_users) == 0);
                LASSERT(ext->oe_state == OES_INV);
                LASSERT(!ext->oe_intree);
 
-               if (ext->oe_osclock) {
-                       cl_lock_put(env, ext->oe_osclock);
-                       ext->oe_osclock = NULL;
+               if (ext->oe_dlmlock != NULL) {
+                       lu_ref_add(&ext->oe_dlmlock->l_reference,
+                                  "osc_extent", ext);
+                       LDLM_LOCK_PUT(ext->oe_dlmlock);
+                       ext->oe_dlmlock = NULL;
                }
                osc_extent_free(ext);
        }
@@ -362,9 +374,9 @@ static void osc_extent_put(const struct lu_env *env, struct osc_extent *ext)
  */
 static void osc_extent_put_trust(struct osc_extent *ext)
 {
-       LASSERT(cfs_atomic_read(&ext->oe_refc) > 1);
+       LASSERT(atomic_read(&ext->oe_refc) > 1);
        LASSERT(osc_object_is_locked(ext->oe_obj));
-       cfs_atomic_dec(&ext->oe_refc);
+       atomic_dec(&ext->oe_refc);
 }
 
 /**
@@ -426,7 +438,7 @@ static void osc_extent_insert(struct osc_object *obj, struct osc_extent *ext)
                else if (ext->oe_start > tmp->oe_end)
                        n = &(*n)->rb_right;
                else
-                       EASSERTF(0, tmp, EXTSTR, EXTPARA(ext));
+                       EASSERTF(0, tmp, EXTSTR"\n", EXTPARA(ext));
        }
        rb_link_node(&ext->oe_node, parent, n);
        rb_insert_color(&ext->oe_node, &obj->oo_root);
@@ -457,17 +469,17 @@ static struct osc_extent *osc_extent_hold(struct osc_extent *ext)
                osc_extent_state_set(ext, OES_ACTIVE);
                osc_update_pending(obj, OBD_BRW_WRITE, -ext->oe_nr_pages);
        }
-       cfs_atomic_inc(&ext->oe_users);
-       cfs_list_del_init(&ext->oe_link);
+       atomic_inc(&ext->oe_users);
+       list_del_init(&ext->oe_link);
        return osc_extent_get(ext);
 }
 
 static void __osc_extent_remove(struct osc_extent *ext)
 {
        LASSERT(osc_object_is_locked(ext->oe_obj));
-       LASSERT(cfs_list_empty(&ext->oe_pages));
+       LASSERT(list_empty(&ext->oe_pages));
        osc_extent_erase(ext);
-       cfs_list_del_init(&ext->oe_link);
+       list_del_init(&ext->oe_link);
        osc_extent_state_set(ext, OES_INV);
        OSC_EXTENT_DUMP(D_CACHE, ext, "destroyed.\n");
 }
@@ -504,7 +516,7 @@ static int osc_extent_merge(const struct lu_env *env, struct osc_extent *cur,
        if (cur->oe_max_end != victim->oe_max_end)
                return -ERANGE;
 
-       LASSERT(cur->oe_osclock == victim->oe_osclock);
+       LASSERT(cur->oe_dlmlock == victim->oe_dlmlock);
        ppc_bits = osc_cli(obj)->cl_chunkbits - PAGE_CACHE_SHIFT;
        chunk_start = cur->oe_start >> ppc_bits;
        chunk_end   = cur->oe_end   >> ppc_bits;
@@ -521,8 +533,8 @@ static int osc_extent_merge(const struct lu_env *env, struct osc_extent *cur,
        /* only the following bits are needed to merge */
        cur->oe_urgent   |= victim->oe_urgent;
        cur->oe_memalloc |= victim->oe_memalloc;
-       cfs_list_splice_init(&victim->oe_pages, &cur->oe_pages);
-       cfs_list_del_init(&victim->oe_link);
+       list_splice_init(&victim->oe_pages, &cur->oe_pages);
+       list_del_init(&victim->oe_link);
        victim->oe_nr_pages = 0;
 
        osc_extent_get(victim);
@@ -542,11 +554,11 @@ int osc_extent_release(const struct lu_env *env, struct osc_extent *ext)
        int rc = 0;
        ENTRY;
 
-       LASSERT(cfs_atomic_read(&ext->oe_users) > 0);
+       LASSERT(atomic_read(&ext->oe_users) > 0);
        LASSERT(sanity_check(ext) == 0);
        LASSERT(ext->oe_grants > 0);
 
-       if (cfs_atomic_dec_and_lock(&ext->oe_users, &obj->oo_lock)) {
+       if (atomic_dec_and_lock(&ext->oe_users, &obj->oo_lock)) {
                LASSERT(ext->oe_state == OES_ACTIVE);
                if (ext->oe_trunc_pending) {
                        /* a truncate process is waiting for this extent.
@@ -564,8 +576,8 @@ int osc_extent_release(const struct lu_env *env, struct osc_extent *ext)
                        osc_extent_merge(env, ext, next_extent(ext));
 
                        if (ext->oe_urgent)
-                               cfs_list_move_tail(&ext->oe_link,
-                                                  &obj->oo_urgent_exts);
+                               list_move_tail(&ext->oe_link,
+                                              &obj->oo_urgent_exts);
                }
                osc_object_unlock(obj);
 
@@ -584,23 +596,23 @@ static inline int overlapped(struct osc_extent *ex1, struct osc_extent *ex2)
  * Find or create an extent which includes @index, core function to manage
  * extent tree.
  */
-struct osc_extent *osc_extent_find(const struct lu_env *env,
-                                  struct osc_object *obj, pgoff_t index,
-                                  int *grants)
-
+static struct osc_extent *osc_extent_find(const struct lu_env *env,
+                                         struct osc_object *obj, pgoff_t index,
+                                         unsigned int *grants)
 {
        struct client_obd *cli = osc_cli(obj);
-       struct cl_lock    *lock;
+       struct osc_lock   *olck;
+       struct cl_lock_descr *descr;
        struct osc_extent *cur;
        struct osc_extent *ext;
        struct osc_extent *conflict = NULL;
        struct osc_extent *found = NULL;
        pgoff_t    chunk;
        pgoff_t    max_end;
-       int        max_pages; /* max_pages_per_rpc */
-       int        chunksize;
+       unsigned int max_pages; /* max_pages_per_rpc */
+       unsigned int chunksize;
        int        ppc_bits; /* pages per chunk bits */
-       int        chunk_mask;
+       pgoff_t    chunk_mask;
        int        rc;
        ENTRY;
 
@@ -608,9 +620,12 @@ struct osc_extent *osc_extent_find(const struct lu_env *env,
        if (cur == NULL)
                RETURN(ERR_PTR(-ENOMEM));
 
-       lock = cl_lock_at_pgoff(env, osc2cl(obj), index, NULL, 1, 0);
-       LASSERT(lock != NULL);
-       LASSERT(lock->cll_descr.cld_mode >= CLM_WRITE);
+       olck = osc_env_io(env)->oi_write_osclock;
+       LASSERTF(olck != NULL, "page %lu is not covered by lock\n", index);
+       LASSERT(olck->ols_state == OLS_GRANTED);
+
+       descr = &olck->ols_cl.cls_lock->cll_descr;
+       LASSERT(descr->cld_mode >= CLM_WRITE);
 
        LASSERT(cli->cl_chunkbits >= PAGE_CACHE_SHIFT);
        ppc_bits   = cli->cl_chunkbits - PAGE_CACHE_SHIFT;
@@ -622,24 +637,29 @@ struct osc_extent *osc_extent_find(const struct lu_env *env,
        max_pages = cli->cl_max_pages_per_rpc;
        LASSERT((max_pages & ~chunk_mask) == 0);
        max_end = index - (index % max_pages) + max_pages - 1;
-       max_end = min_t(pgoff_t, max_end, lock->cll_descr.cld_end);
+       max_end = min_t(pgoff_t, max_end, descr->cld_end);
 
        /* initialize new extent by parameters so far */
        cur->oe_max_end = max_end;
        cur->oe_start   = index & chunk_mask;
        cur->oe_end     = ((index + ~chunk_mask + 1) & chunk_mask) - 1;
-       if (cur->oe_start < lock->cll_descr.cld_start)
-               cur->oe_start = lock->cll_descr.cld_start;
+       if (cur->oe_start < descr->cld_start)
+               cur->oe_start = descr->cld_start;
        if (cur->oe_end > max_end)
                cur->oe_end = max_end;
-       cur->oe_osclock = lock;
        cur->oe_grants  = 0;
        cur->oe_mppr    = max_pages;
+       if (olck->ols_dlmlock != NULL) {
+               LASSERT(olck->ols_hold);
+               cur->oe_dlmlock = LDLM_LOCK_GET(olck->ols_dlmlock);
+               lu_ref_add(&olck->ols_dlmlock->l_reference, "osc_extent", cur);
+       }
 
        /* grants has been allocated by caller */
        LASSERTF(*grants >= chunksize + cli->cl_extent_tax,
                 "%u/%u/%u.\n", *grants, chunksize, cli->cl_extent_tax);
-       LASSERTF((max_end - cur->oe_start) < max_pages, EXTSTR, EXTPARA(cur));
+       LASSERTF((max_end - cur->oe_start) < max_pages, EXTSTR"\n",
+                EXTPARA(cur));
 
 restart:
        osc_object_lock(obj);
@@ -647,17 +667,17 @@ restart:
        if (ext == NULL)
                ext = first_extent(obj);
        while (ext != NULL) {
-               loff_t ext_chk_start = ext->oe_start >> ppc_bits;
-               loff_t ext_chk_end   = ext->oe_end   >> ppc_bits;
+               pgoff_t ext_chk_start = ext->oe_start >> ppc_bits;
+               pgoff_t ext_chk_end   = ext->oe_end   >> ppc_bits;
 
                LASSERT(sanity_check_nolock(ext) == 0);
                if (chunk > ext_chk_end + 1)
                        break;
 
                /* if covering by different locks, no chance to match */
-               if (lock != ext->oe_osclock) {
+               if (olck->ols_dlmlock != ext->oe_dlmlock) {
                        EASSERTF(!overlapped(ext, cur), ext,
-                                EXTSTR, EXTPARA(cur));
+                                EXTSTR"\n", EXTPARA(cur));
 
                        ext = next_extent(ext);
                        continue;
@@ -678,7 +698,7 @@ restart:
                         * full contain. */
                        EASSERTF((ext->oe_start <= cur->oe_start &&
                                  ext->oe_end >= cur->oe_end),
-                                ext, EXTSTR, EXTPARA(cur));
+                                ext, EXTSTR"\n", EXTPARA(cur));
 
                        if (ext->oe_state > OES_CACHE || ext->oe_fsync_wait) {
                                /* for simplicity, we wait for this extent to
@@ -751,7 +771,7 @@ restart:
        if (found != NULL) {
                LASSERT(conflict == NULL);
                if (!IS_ERR(found)) {
-                       LASSERT(found->oe_osclock == cur->oe_osclock);
+                       LASSERT(found->oe_dlmlock == cur->oe_dlmlock);
                        OSC_EXTENT_DUMP(D_CACHE, found,
                                        "found caching ext for %lu.\n", index);
                }
@@ -766,7 +786,7 @@ restart:
                found = osc_extent_hold(cur);
                osc_extent_insert(obj, cur);
                OSC_EXTENT_DUMP(D_CACHE, cur, "add into tree %lu/%lu.\n",
-                               index, lock->cll_descr.cld_end);
+                               index, descr->cld_end);
        }
        osc_object_unlock(obj);
 
@@ -803,7 +823,7 @@ int osc_extent_finish(const struct lu_env *env, struct osc_extent *ext,
        int nr_pages = ext->oe_nr_pages;
        int lost_grant = 0;
        int blocksize = cli->cl_import->imp_obd->obd_osfs.os_bsize ? : 4096;
-       __u64 last_off = 0;
+       loff_t last_off = 0;
        int last_count = -1;
        ENTRY;
 
@@ -811,10 +831,12 @@ int osc_extent_finish(const struct lu_env *env, struct osc_extent *ext,
 
        ext->oe_rc = rc ?: ext->oe_nr_pages;
        EASSERT(ergo(rc == 0, ext->oe_state == OES_RPC), ext);
-       cfs_list_for_each_entry_safe(oap, tmp, &ext->oe_pages,
+
+       osc_lru_add_batch(cli, &ext->oe_pages);
+       list_for_each_entry_safe(oap, tmp, &ext->oe_pages,
                                     oap_pending_item) {
-               cfs_list_del_init(&oap->oap_rpc_item);
-               cfs_list_del_init(&oap->oap_pending_item);
+               list_del_init(&oap->oap_rpc_item);
+               list_del_init(&oap->oap_pending_item);
                if (last_off <= oap->oap_obj_off) {
                        last_off = oap->oap_obj_off;
                        last_count = oap->oap_count;
@@ -832,9 +854,9 @@ int osc_extent_finish(const struct lu_env *env, struct osc_extent *ext,
                /* For short writes we shouldn't count parts of pages that
                 * span a whole chunk on the OST side, or our accounting goes
                 * wrong.  Should match the code in filter_grant_check. */
-               int offset = oap->oap_page_off & ~CFS_PAGE_MASK;
-               int count = oap->oap_count + (offset & (blocksize - 1));
-               int end = (offset + oap->oap_count) & (blocksize - 1);
+               int offset = last_off & ~PAGE_MASK;
+               int count = last_count + (offset & (blocksize - 1));
+               int end = (offset + last_count) & (blocksize - 1);
                if (end)
                        count += blocksize - end;
 
@@ -849,7 +871,7 @@ int osc_extent_finish(const struct lu_env *env, struct osc_extent *ext,
        RETURN(0);
 }
 
-static int extent_wait_cb(struct osc_extent *ext, int state)
+static int extent_wait_cb(struct osc_extent *ext, enum osc_extent_state state)
 {
        int ret;
 
@@ -864,7 +886,7 @@ static int extent_wait_cb(struct osc_extent *ext, int state)
  * Wait for the extent's state to become @state.
  */
 static int osc_extent_wait(const struct lu_env *env, struct osc_extent *ext,
-                          int state)
+                          enum osc_extent_state state)
 {
        struct osc_object *obj = ext->oe_obj;
        struct l_wait_info lwi = LWI_TIMEOUT_INTR(cfs_time_seconds(600), NULL,
@@ -893,8 +915,8 @@ static int osc_extent_wait(const struct lu_env *env, struct osc_extent *ext,
        rc = l_wait_event(ext->oe_waitq, extent_wait_cb(ext, state), &lwi);
        if (rc == -ETIMEDOUT) {
                OSC_EXTENT_DUMP(D_ERROR, ext,
-                       "%s: wait ext to %d timedout, recovery in progress?\n",
-                       osc_export(obj)->exp_obd->obd_name, state);
+                       "%s: wait ext to %u timedout, recovery in progress?\n",
+                       cli_name(osc_cli(obj)), state);
 
                lwi = LWI_INTR(NULL, NULL);
                rc = l_wait_event(ext->oe_waitq, extent_wait_cb(ext, state),
@@ -942,32 +964,31 @@ static int osc_extent_truncate(struct osc_extent *ext, pgoff_t trunc_index,
        if (rc < 0)
                GOTO(out, rc);
 
-       /* discard all pages with index greater then trunc_index */
-       cfs_list_for_each_entry_safe(oap, tmp, &ext->oe_pages,
+       /* discard all pages with index greater than trunc_index */
+       list_for_each_entry_safe(oap, tmp, &ext->oe_pages,
                                     oap_pending_item) {
-               struct cl_page  *sub  = oap2cl_page(oap);
-               struct cl_page  *page = cl_page_top(sub);
+               pgoff_t index = osc_index(oap2osc(oap));
+               struct cl_page  *page = oap2cl_page(oap);
 
-               LASSERT(cfs_list_empty(&oap->oap_rpc_item));
+               LASSERT(list_empty(&oap->oap_rpc_item));
 
                /* only discard the pages with their index greater than
                 * trunc_index, and ... */
-               if (sub->cp_index < trunc_index ||
-                   (sub->cp_index == trunc_index && partial)) {
+               if (index < trunc_index ||
+                   (index == trunc_index && partial)) {
                        /* accounting how many pages remaining in the chunk
                         * so that we can calculate grants correctly. */
-                       if (sub->cp_index >> ppc_bits == trunc_chunk)
+                       if (index >> ppc_bits == trunc_chunk)
                                ++pages_in_chunk;
                        continue;
                }
 
-               cfs_list_del_init(&oap->oap_pending_item);
+               list_del_init(&oap->oap_pending_item);
 
                cl_page_get(page);
                lu_ref_add(&page->cp_reference, "truncate", current);
 
                if (cl_page_own(env, io, page) == 0) {
-                       cl_page_unmap(env, io, page);
                        cl_page_discard(env, io, page);
                        cl_page_disown(env, io, page);
                } else {
@@ -1035,7 +1056,7 @@ static int osc_extent_make_ready(const struct lu_env *env,
        struct osc_async_page *oap;
        struct osc_async_page *last = NULL;
        struct osc_object *obj = ext->oe_obj;
-       int page_count = 0;
+       unsigned int page_count = 0;
        int rc;
        ENTRY;
 
@@ -1047,7 +1068,7 @@ static int osc_extent_make_ready(const struct lu_env *env,
 
        OSC_EXTENT_DUMP(D_CACHE, ext, "make ready\n");
 
-       cfs_list_for_each_entry(oap, &ext->oe_pages, oap_pending_item) {
+       list_for_each_entry(oap, &ext->oe_pages, oap_pending_item) {
                ++page_count;
                if (last == NULL || last->oap_obj_off < oap->oap_obj_off)
                        last = oap;
@@ -1076,9 +1097,10 @@ static int osc_extent_make_ready(const struct lu_env *env,
        /* the last page is the only one we need to refresh its count by
         * the size of file. */
        if (!(last->oap_async_flags & ASYNC_COUNT_STABLE)) {
-               last->oap_count = osc_refresh_count(env, last, OBD_BRW_WRITE);
-               LASSERT(last->oap_count > 0);
-               LASSERT(last->oap_page_off + last->oap_count <= PAGE_CACHE_SIZE);
+               int last_oap_count = osc_refresh_count(env, last, OBD_BRW_WRITE);
+               LASSERT(last_oap_count > 0);
+               LASSERT(last->oap_page_off + last_oap_count <= PAGE_CACHE_SIZE);
+               last->oap_count = last_oap_count;
                spin_lock(&last->oap_lock);
                last->oap_async_flags |= ASYNC_COUNT_STABLE;
                spin_unlock(&last->oap_lock);
@@ -1086,7 +1108,7 @@ static int osc_extent_make_ready(const struct lu_env *env,
 
        /* for the rest of pages, we don't need to call osf_refresh_count()
         * because it's known they are not the last page */
-       cfs_list_for_each_entry(oap, &ext->oe_pages, oap_pending_item) {
+       list_for_each_entry(oap, &ext->oe_pages, oap_pending_item) {
                if (!(oap->oap_async_flags & ASYNC_COUNT_STABLE)) {
                        oap->oap_count = PAGE_CACHE_SIZE - oap->oap_page_off;
                        spin_lock(&oap->oap_lock);
@@ -1109,7 +1131,8 @@ static int osc_extent_make_ready(const struct lu_env *env,
  * called to expand the extent for the same IO. To expand the extent, the
  * page index must be in the same or next chunk of ext->oe_end.
  */
-static int osc_extent_expand(struct osc_extent *ext, pgoff_t index, int *grants)
+static int osc_extent_expand(struct osc_extent *ext, pgoff_t index,
+                            unsigned int *grants)
 {
        struct osc_object *obj = ext->oe_obj;
        struct client_obd *cli = osc_cli(obj);
@@ -1118,7 +1141,7 @@ static int osc_extent_expand(struct osc_extent *ext, pgoff_t index, int *grants)
        pgoff_t chunk = index >> ppc_bits;
        pgoff_t end_chunk;
        pgoff_t end_index;
-       int chunksize = 1 << cli->cl_chunkbits;
+       unsigned int chunksize = 1 << cli->cl_chunkbits;
        int rc = 0;
        ENTRY;
 
@@ -1170,15 +1193,15 @@ static void osc_extent_tree_dump0(int level, struct osc_object *obj,
                OSC_EXTENT_DUMP(level, ext, "in tree %d.\n", cnt++);
 
        cnt = 1;
-       cfs_list_for_each_entry(ext, &obj->oo_hp_exts, oe_link)
+       list_for_each_entry(ext, &obj->oo_hp_exts, oe_link)
                OSC_EXTENT_DUMP(level, ext, "hp %d.\n", cnt++);
 
        cnt = 1;
-       cfs_list_for_each_entry(ext, &obj->oo_urgent_exts, oe_link)
+       list_for_each_entry(ext, &obj->oo_urgent_exts, oe_link)
                OSC_EXTENT_DUMP(level, ext, "urgent %d.\n", cnt++);
 
        cnt = 1;
-       cfs_list_for_each_entry(ext, &obj->oo_reading_exts, oe_link)
+       list_for_each_entry(ext, &obj->oo_reading_exts, oe_link)
                OSC_EXTENT_DUMP(level, ext, "reading %d.\n", cnt++);
        /* osc_object_unlock(obj); */
 }
@@ -1187,8 +1210,8 @@ static void osc_extent_tree_dump0(int level, struct osc_object *obj,
 
 static inline int osc_is_ready(struct osc_object *osc)
 {
-       return !cfs_list_empty(&osc->oo_ready_item) ||
-              !cfs_list_empty(&osc->oo_hp_ready_item);
+       return !list_empty(&osc->oo_ready_item) ||
+              !list_empty(&osc->oo_hp_ready_item);
 }
 
 #define OSC_IO_DEBUG(OSC, STR, args...)                                               \
@@ -1196,10 +1219,10 @@ static inline int osc_is_ready(struct osc_object *osc)
               (OSC), osc_is_ready(OSC),                                       \
               list_empty_marker(&(OSC)->oo_hp_ready_item),                    \
               list_empty_marker(&(OSC)->oo_ready_item),                       \
-              cfs_atomic_read(&(OSC)->oo_nr_writes),                          \
+              atomic_read(&(OSC)->oo_nr_writes),                              \
               list_empty_marker(&(OSC)->oo_hp_exts),                          \
               list_empty_marker(&(OSC)->oo_urgent_exts),                      \
-              cfs_atomic_read(&(OSC)->oo_nr_reads),                           \
+              atomic_read(&(OSC)->oo_nr_reads),                               \
               list_empty_marker(&(OSC)->oo_reading_exts),                     \
               ##args)
 
@@ -1207,7 +1230,7 @@ static int osc_make_ready(const struct lu_env *env, struct osc_async_page *oap,
                          int cmd)
 {
        struct osc_page *opg  = oap2osc_page(oap);
-       struct cl_page  *page = cl_page_top(oap2cl_page(oap));
+       struct cl_page  *page = oap2cl_page(oap);
        int result;
 
        LASSERT(cmd == OBD_BRW_WRITE); /* no cached reads */
@@ -1223,7 +1246,7 @@ static int osc_refresh_count(const struct lu_env *env,
                             struct osc_async_page *oap, int cmd)
 {
        struct osc_page  *opg = oap2osc_page(oap);
-       struct cl_page   *page = oap2cl_page(oap);
+       pgoff_t index = osc_index(oap2osc(oap));
        struct cl_object *obj;
        struct cl_attr   *attr = &osc_env_info(env)->oti_attr;
 
@@ -1241,10 +1264,10 @@ static int osc_refresh_count(const struct lu_env *env,
        if (result < 0)
                return result;
        kms = attr->cat_kms;
-       if (cl_offset(obj, page->cp_index) >= kms)
+       if (cl_offset(obj, index) >= kms)
                /* catch race with truncate */
                return 0;
-       else if (cl_offset(obj, page->cp_index + 1) > kms)
+       else if (cl_offset(obj, index + 1) > kms)
                /* catch sub-page write at end of file */
                return kms % PAGE_CACHE_SIZE;
        else
@@ -1255,16 +1278,17 @@ static int osc_completion(const struct lu_env *env, struct osc_async_page *oap,
                          int cmd, int rc)
 {
        struct osc_page   *opg  = oap2osc_page(oap);
-       struct cl_page    *page = cl_page_top(oap2cl_page(oap));
-       struct osc_object *obj  = cl2osc(opg->ops_cl.cpl_obj);
+       struct cl_page    *page = oap2cl_page(oap);
        enum cl_req_type   crt;
        int srvlock;
 
        ENTRY;
 
        cmd &= ~OBD_BRW_NOQUOTA;
-       LASSERT(equi(page->cp_state == CPS_PAGEIN,  cmd == OBD_BRW_READ));
-       LASSERT(equi(page->cp_state == CPS_PAGEOUT, cmd == OBD_BRW_WRITE));
+       LASSERTF(equi(page->cp_state == CPS_PAGEIN,  cmd == OBD_BRW_READ),
+                "cp_state:%u, cmd:%d\n", page->cp_state, cmd);
+       LASSERTF(equi(page->cp_state == CPS_PAGEOUT, cmd == OBD_BRW_WRITE),
+               "cp_state:%u, cmd:%d\n", page->cp_state, cmd);
        LASSERT(opg->ops_transfer_pinned);
 
        /*
@@ -1279,13 +1303,6 @@ static int osc_completion(const struct lu_env *env, struct osc_async_page *oap,
        /* Clear opg->ops_transfer_pinned before VM lock is released. */
        opg->ops_transfer_pinned = 0;
 
-       spin_lock(&obj->oo_seatbelt);
-       LASSERT(opg->ops_submitter != NULL);
-       LASSERT(!cfs_list_empty(&opg->ops_inflight));
-       cfs_list_del_init(&opg->ops_inflight);
-       opg->ops_submitter = NULL;
-       spin_unlock(&obj->oo_seatbelt);
-
        opg->ops_submit_time = 0;
        srvlock = oap->oap_brw_flags & OBD_BRW_SRVLOCK;
 
@@ -1293,7 +1310,7 @@ static int osc_completion(const struct lu_env *env, struct osc_async_page *oap,
        if (rc == 0 && srvlock) {
                struct lu_device *ld    = opg->ops_cl.cpl_obj->co_lu.lo_dev;
                struct osc_stats *stats = &lu2osc_dev(ld)->od_stats;
-               int bytes = oap->oap_count;
+               size_t bytes = oap->oap_count;
 
                if (crt == CRT_READ)
                        stats->os_lockless_reads += bytes;
@@ -1313,29 +1330,29 @@ static int osc_completion(const struct lu_env *env, struct osc_async_page *oap,
        RETURN(0);
 }
 
-#define OSC_DUMP_GRANT(lvl, cli, fmt, args...) do {                          \
-       struct client_obd *__tmp = (cli);                                     \
-       CDEBUG(lvl, "%s: grant { dirty: %ld/%ld dirty_pages: %d/%d "          \
-              "dropped: %ld avail: %ld, reserved: %ld, flight: %d } "        \
-              "lru {in list: %d, left: %d, waiters: %d }" fmt,               \
-              __tmp->cl_import->imp_obd->obd_name,                           \
-              __tmp->cl_dirty, __tmp->cl_dirty_max,                          \
-              cfs_atomic_read(&obd_dirty_pages), obd_max_dirty_pages,        \
-              __tmp->cl_lost_grant, __tmp->cl_avail_grant,                   \
-              __tmp->cl_reserved_grant, __tmp->cl_w_in_flight,               \
-              cfs_atomic_read(&__tmp->cl_lru_in_list),                       \
-              cfs_atomic_read(&__tmp->cl_lru_busy),                          \
-              cfs_atomic_read(&__tmp->cl_lru_shrinkers), ##args);            \
+#define OSC_DUMP_GRANT(lvl, cli, fmt, args...) do {                    \
+       struct client_obd *__tmp = (cli);                               \
+       CDEBUG(lvl, "%s: grant { dirty: %lu/%lu dirty_pages: %ld/%lu "  \
+              "dropped: %ld avail: %ld, reserved: %ld, flight: %d }"   \
+              "lru {in list: %ld, left: %ld, waiters: %d }"fmt"\n",    \
+              cli_name(__tmp),                                         \
+              __tmp->cl_dirty_pages, __tmp->cl_dirty_max_pages,        \
+              atomic_long_read(&obd_dirty_pages), obd_max_dirty_pages, \
+              __tmp->cl_lost_grant, __tmp->cl_avail_grant,             \
+              __tmp->cl_reserved_grant, __tmp->cl_w_in_flight,         \
+              atomic_long_read(&__tmp->cl_lru_in_list),                \
+              atomic_long_read(&__tmp->cl_lru_busy),                   \
+              atomic_read(&__tmp->cl_lru_shrinkers), ##args);          \
 } while (0)
 
 /* caller must hold loi_list_lock */
 static void osc_consume_write_grant(struct client_obd *cli,
                                    struct brw_page *pga)
 {
-       LASSERT(spin_is_locked(&cli->cl_loi_list_lock.lock));
+       assert_spin_locked(&cli->cl_loi_list_lock);
        LASSERT(!(pga->flag & OBD_BRW_FROM_GRANT));
-       cfs_atomic_inc(&obd_dirty_pages);
-       cli->cl_dirty += PAGE_CACHE_SIZE;
+       atomic_long_inc(&obd_dirty_pages);
+       cli->cl_dirty_pages++;
        pga->flag |= OBD_BRW_FROM_GRANT;
        CDEBUG(D_CACHE, "using %lu grant credits for brw %p page %p\n",
               PAGE_CACHE_SIZE, pga, pga->pg);
@@ -1349,19 +1366,19 @@ static void osc_release_write_grant(struct client_obd *cli,
 {
        ENTRY;
 
-       LASSERT(spin_is_locked(&cli->cl_loi_list_lock.lock));
+       assert_spin_locked(&cli->cl_loi_list_lock);
        if (!(pga->flag & OBD_BRW_FROM_GRANT)) {
                EXIT;
                return;
        }
 
        pga->flag &= ~OBD_BRW_FROM_GRANT;
-       cfs_atomic_dec(&obd_dirty_pages);
-       cli->cl_dirty -= PAGE_CACHE_SIZE;
+       atomic_long_dec(&obd_dirty_pages);
+       cli->cl_dirty_pages--;
        if (pga->flag & OBD_BRW_NOCACHE) {
                pga->flag &= ~OBD_BRW_NOCACHE;
-               cfs_atomic_dec(&obd_dirty_transit_pages);
-               cli->cl_dirty_transit -= PAGE_CACHE_SIZE;
+               atomic_long_dec(&obd_dirty_transit_pages);
+               cli->cl_dirty_transit--;
        }
        EXIT;
 }
@@ -1400,14 +1417,14 @@ static void __osc_unreserve_grant(struct client_obd *cli,
        }
 }
 
-void osc_unreserve_grant(struct client_obd *cli,
-                        unsigned int reserved, unsigned int unused)
+static void osc_unreserve_grant(struct client_obd *cli,
+                               unsigned int reserved, unsigned int unused)
 {
-       client_obd_list_lock(&cli->cl_loi_list_lock);
+       spin_lock(&cli->cl_loi_list_lock);
        __osc_unreserve_grant(cli, reserved, unused);
        if (unused > 0)
                osc_wake_cache_waiters(cli);
-       client_obd_list_unlock(&cli->cl_loi_list_lock);
+       spin_unlock(&cli->cl_loi_list_lock);
 }
 
 /**
@@ -1426,11 +1443,11 @@ void osc_unreserve_grant(struct client_obd *cli,
 static void osc_free_grant(struct client_obd *cli, unsigned int nr_pages,
                           unsigned int lost_grant)
 {
-       int grant = (1 << cli->cl_chunkbits) + cli->cl_extent_tax;
+       unsigned long grant = (1 << cli->cl_chunkbits) + cli->cl_extent_tax;
 
-       client_obd_list_lock(&cli->cl_loi_list_lock);
-       cfs_atomic_sub(nr_pages, &obd_dirty_pages);
-       cli->cl_dirty -= nr_pages << PAGE_CACHE_SHIFT;
+       spin_lock(&cli->cl_loi_list_lock);
+       atomic_long_sub(nr_pages, &obd_dirty_pages);
+       cli->cl_dirty_pages -= nr_pages;
        cli->cl_lost_grant += lost_grant;
        if (cli->cl_avail_grant < grant && cli->cl_lost_grant >= grant) {
                /* borrow some grant from truncate to avoid the case that
@@ -1439,10 +1456,10 @@ static void osc_free_grant(struct client_obd *cli, unsigned int nr_pages,
                cli->cl_avail_grant += grant;
        }
        osc_wake_cache_waiters(cli);
-       client_obd_list_unlock(&cli->cl_loi_list_lock);
+       spin_unlock(&cli->cl_loi_list_lock);
        CDEBUG(D_CACHE, "lost %u grant: %lu avail: %lu dirty: %lu\n",
               lost_grant, cli->cl_lost_grant,
-              cli->cl_avail_grant, cli->cl_dirty);
+              cli->cl_avail_grant, cli->cl_dirty_pages << PAGE_CACHE_SHIFT);
 }
 
 /**
@@ -1451,9 +1468,9 @@ static void osc_free_grant(struct client_obd *cli, unsigned int nr_pages,
  */
 static void osc_exit_cache(struct client_obd *cli, struct osc_async_page *oap)
 {
-       client_obd_list_lock(&cli->cl_loi_list_lock);
+       spin_lock(&cli->cl_loi_list_lock);
        osc_release_write_grant(cli, &oap->oap_brw_page);
-       client_obd_list_unlock(&cli->cl_loi_list_lock);
+       spin_unlock(&cli->cl_loi_list_lock);
 }
 
 /**
@@ -1466,18 +1483,18 @@ static int osc_enter_cache_try(struct client_obd *cli,
 {
        int rc;
 
-       OSC_DUMP_GRANT(D_CACHE, cli, "need:%d.\n", bytes);
+       OSC_DUMP_GRANT(D_CACHE, cli, "need:%d\n", bytes);
 
        rc = osc_reserve_grant(cli, bytes);
        if (rc < 0)
                return 0;
 
-       if (cli->cl_dirty + PAGE_CACHE_SIZE <= cli->cl_dirty_max &&
-           cfs_atomic_read(&obd_dirty_pages) + 1 <= obd_max_dirty_pages) {
+       if (cli->cl_dirty_pages < cli->cl_dirty_max_pages &&
+           1 + atomic_long_read(&obd_dirty_pages) <= obd_max_dirty_pages) {
                osc_consume_write_grant(cli, &oap->oap_brw_page);
                if (transient) {
-                       cli->cl_dirty_transit += PAGE_CACHE_SIZE;
-                       cfs_atomic_inc(&obd_dirty_transit_pages);
+                       cli->cl_dirty_transit++;
+                       atomic_long_inc(&obd_dirty_transit_pages);
                        oap->oap_brw_flags |= OBD_BRW_NOCACHE;
                }
                rc = 1;
@@ -1491,9 +1508,9 @@ static int osc_enter_cache_try(struct client_obd *cli,
 static int ocw_granted(struct client_obd *cli, struct osc_cache_waiter *ocw)
 {
        int rc;
-       client_obd_list_lock(&cli->cl_loi_list_lock);
-       rc = cfs_list_empty(&ocw->ocw_entry);
-       client_obd_list_unlock(&cli->cl_loi_list_lock);
+       spin_lock(&cli->cl_loi_list_lock);
+       rc = list_empty(&ocw->ocw_entry);
+       spin_unlock(&cli->cl_loi_list_lock);
        return rc;
 }
 
@@ -1507,28 +1524,34 @@ static int ocw_granted(struct client_obd *cli, struct osc_cache_waiter *ocw)
 static int osc_enter_cache(const struct lu_env *env, struct client_obd *cli,
                           struct osc_async_page *oap, int bytes)
 {
-       struct osc_object *osc = oap->oap_obj;
-       struct lov_oinfo  *loi = osc->oo_oinfo;
-       struct osc_cache_waiter ocw;
-       struct l_wait_info lwi = LWI_TIMEOUT_INTR(cfs_time_seconds(600), NULL,
-                                                 LWI_ON_SIGNAL_NOOP, NULL);
-       int rc = -EDQUOT;
+       struct osc_object       *osc = oap->oap_obj;
+       struct lov_oinfo        *loi = osc->oo_oinfo;
+       struct osc_cache_waiter  ocw;
+       struct l_wait_info       lwi;
+       int                      rc = -EDQUOT;
        ENTRY;
 
-       OSC_DUMP_GRANT(D_CACHE, cli, "need:%d.\n", bytes);
+       lwi = LWI_TIMEOUT_INTR(cfs_time_seconds(AT_OFF ? obd_timeout : at_max),
+                              NULL, LWI_ON_SIGNAL_NOOP, NULL);
+
+       OSC_DUMP_GRANT(D_CACHE, cli, "need:%d\n", bytes);
 
-       client_obd_list_lock(&cli->cl_loi_list_lock);
+       spin_lock(&cli->cl_loi_list_lock);
 
        /* force the caller to try sync io.  this can jump the list
         * of queued writes and create a discontiguous rpc stream */
        if (OBD_FAIL_CHECK(OBD_FAIL_OSC_NO_GRANT) ||
-           cli->cl_dirty_max < PAGE_CACHE_SIZE     ||
-           cli->cl_ar.ar_force_sync || loi->loi_ar.ar_force_sync)
+           cli->cl_dirty_max_pages == 0 ||
+           cli->cl_ar.ar_force_sync || loi->loi_ar.ar_force_sync) {
+               OSC_DUMP_GRANT(D_CACHE, cli, "forced sync i/o\n");
                GOTO(out, rc = -EDQUOT);
+       }
 
        /* Hopefully normal case - cache space and write credits available */
-       if (osc_enter_cache_try(cli, oap, bytes, 0))
+       if (osc_enter_cache_try(cli, oap, bytes, 0)) {
+               OSC_DUMP_GRANT(D_CACHE, cli, "granted from cache\n");
                GOTO(out, rc = 0);
+       }
 
        /* We can get here for two reasons: too many dirty pages in cache, or
         * run out of grants. In both cases we should write dirty pages out.
@@ -1539,85 +1562,93 @@ static int osc_enter_cache(const struct lu_env *env, struct client_obd *cli,
        init_waitqueue_head(&ocw.ocw_waitq);
        ocw.ocw_oap   = oap;
        ocw.ocw_grant = bytes;
-       while (cli->cl_dirty > 0 || cli->cl_w_in_flight > 0) {
-               cfs_list_add_tail(&ocw.ocw_entry, &cli->cl_cache_waiters);
+       while (cli->cl_dirty_pages > 0 || cli->cl_w_in_flight > 0) {
+               list_add_tail(&ocw.ocw_entry, &cli->cl_cache_waiters);
                ocw.ocw_rc = 0;
-               client_obd_list_unlock(&cli->cl_loi_list_lock);
+               spin_unlock(&cli->cl_loi_list_lock);
 
                osc_io_unplug_async(env, cli, NULL);
 
                CDEBUG(D_CACHE, "%s: sleeping for cache space @ %p for %p\n",
-                      cli->cl_import->imp_obd->obd_name, &ocw, oap);
+                      cli_name(cli), &ocw, oap);
 
                rc = l_wait_event(ocw.ocw_waitq, ocw_granted(cli, &ocw), &lwi);
 
-               client_obd_list_lock(&cli->cl_loi_list_lock);
+               spin_lock(&cli->cl_loi_list_lock);
 
-               /* l_wait_event is interrupted by signal, or timed out */
                if (rc < 0) {
-                       switch (rc) {
-                       case -ETIMEDOUT:
-                               OSC_DUMP_GRANT(D_ERROR, cli,
-                                               "try to reserve %d.\n", bytes);
-                               osc_extent_tree_dump(D_ERROR, osc);
-                               rc = -EDQUOT;
-                               break;
-                       case -EINTR:
-                               /* Ensures restartability - LU-3581 */
-                               rc = -ERESTARTSYS;
-                               break;
-                       default:
-                               CDEBUG(D_CACHE, "%s: event for cache space @"
-                                      " %p never arrived due to %d\n",
-                                      cli->cl_import->imp_obd->obd_name,
-                                      &ocw, rc);
-                               break;
-                       }
-                       cfs_list_del_init(&ocw.ocw_entry);
-                       GOTO(out, rc);
+                       /* l_wait_event is interrupted by signal or timed out */
+                       list_del_init(&ocw.ocw_entry);
+                       break;
                }
-
-               LASSERT(cfs_list_empty(&ocw.ocw_entry));
+               LASSERT(list_empty(&ocw.ocw_entry));
                rc = ocw.ocw_rc;
 
                if (rc != -EDQUOT)
-                       GOTO(out, rc);
-               if (osc_enter_cache_try(cli, oap, bytes, 0))
-                       GOTO(out, rc = 0);
+                       break;
+               if (osc_enter_cache_try(cli, oap, bytes, 0)) {
+                       rc = 0;
+                       break;
+               }
+       }
+
+       switch (rc) {
+       case 0:
+               OSC_DUMP_GRANT(D_CACHE, cli, "finally got grant space\n");
+               break;
+       case -ETIMEDOUT:
+               OSC_DUMP_GRANT(D_CACHE, cli,
+                              "timeout, fall back to sync i/o\n");
+               osc_extent_tree_dump(D_CACHE, osc);
+               /* fall back to synchronous I/O */
+               rc = -EDQUOT;
+               break;
+       case -EINTR:
+               /* Ensures restartability - LU-3581 */
+               OSC_DUMP_GRANT(D_CACHE, cli, "interrupted\n");
+               rc = -ERESTARTSYS;
+               break;
+       case -EDQUOT:
+               OSC_DUMP_GRANT(D_CACHE, cli,
+                              "no grant space, fall back to sync i/o\n");
+               break;
+       default:
+               CDEBUG(D_CACHE, "%s: event for cache space @ %p never arrived "
+                      "due to %d, fall back to sync i/o\n",
+                      cli_name(cli), &ocw, rc);
+               break;
        }
        EXIT;
 out:
-       client_obd_list_unlock(&cli->cl_loi_list_lock);
-       OSC_DUMP_GRANT(D_CACHE, cli, "returned %d.\n", rc);
+       spin_unlock(&cli->cl_loi_list_lock);
        RETURN(rc);
 }
 
 /* caller must hold loi_list_lock */
 void osc_wake_cache_waiters(struct client_obd *cli)
 {
-       cfs_list_t *l, *tmp;
+       struct list_head *l, *tmp;
        struct osc_cache_waiter *ocw;
 
        ENTRY;
-       cfs_list_for_each_safe(l, tmp, &cli->cl_cache_waiters) {
-               ocw = cfs_list_entry(l, struct osc_cache_waiter, ocw_entry);
-               cfs_list_del_init(&ocw->ocw_entry);
+       list_for_each_safe(l, tmp, &cli->cl_cache_waiters) {
+               ocw = list_entry(l, struct osc_cache_waiter, ocw_entry);
+               list_del_init(&ocw->ocw_entry);
 
                ocw->ocw_rc = -EDQUOT;
                /* we can't dirty more */
-               if ((cli->cl_dirty + PAGE_CACHE_SIZE > cli->cl_dirty_max) ||
-                   (cfs_atomic_read(&obd_dirty_pages) + 1 >
+               if ((cli->cl_dirty_pages  >= cli->cl_dirty_max_pages) ||
+                   (1 + atomic_long_read(&obd_dirty_pages) >
                     obd_max_dirty_pages)) {
                        CDEBUG(D_CACHE, "no dirty room: dirty: %ld "
-                              "osc max %ld, sys max %d\n", cli->cl_dirty,
-                              cli->cl_dirty_max, obd_max_dirty_pages);
+                              "osc max %ld, sys max %ld\n",
+                              cli->cl_dirty_pages, cli->cl_dirty_max_pages,
+                              obd_max_dirty_pages);
                        goto wakeup;
                }
 
-               ocw->ocw_rc = 0;
-               if (!osc_enter_cache_try(cli, ocw->ocw_oap, ocw->ocw_grant, 0))
-                       ocw->ocw_rc = -EDQUOT;
-
+               if (osc_enter_cache_try(cli, ocw->ocw_oap, ocw->ocw_grant, 0))
+                       ocw->ocw_rc = 0;
 wakeup:
                CDEBUG(D_CACHE, "wake up %p for oap %p, avail grant %ld, %d\n",
                       ocw, ocw->ocw_oap, cli->cl_avail_grant, ocw->ocw_rc);
@@ -1630,7 +1661,7 @@ wakeup:
 
 static int osc_max_rpc_in_flight(struct client_obd *cli, struct osc_object *osc)
 {
-       int hprpc = !!cfs_list_empty(&osc->oo_hp_exts);
+       int hprpc = !!list_empty(&osc->oo_hp_exts);
        return rpcs_in_flight(cli) >= cli->cl_max_rpcs_in_flight + hprpc;
 }
 
@@ -1651,39 +1682,39 @@ static int osc_makes_rpc(struct client_obd *cli, struct osc_object *osc,
                invalid_import = 1;
 
        if (cmd & OBD_BRW_WRITE) {
-               if (cfs_atomic_read(&osc->oo_nr_writes) == 0)
+               if (atomic_read(&osc->oo_nr_writes) == 0)
                        RETURN(0);
                if (invalid_import) {
                        CDEBUG(D_CACHE, "invalid import forcing RPC\n");
                        RETURN(1);
                }
-               if (!cfs_list_empty(&osc->oo_hp_exts)) {
+               if (!list_empty(&osc->oo_hp_exts)) {
                        CDEBUG(D_CACHE, "high prio request forcing RPC\n");
                        RETURN(1);
                }
-               if (!cfs_list_empty(&osc->oo_urgent_exts)) {
+               if (!list_empty(&osc->oo_urgent_exts)) {
                        CDEBUG(D_CACHE, "urgent request forcing RPC\n");
                        RETURN(1);
                }
                /* trigger a write rpc stream as long as there are dirtiers
                 * waiting for space.  as they're waiting, they're not going to
                 * create more pages to coalesce with what's waiting.. */
-               if (!cfs_list_empty(&cli->cl_cache_waiters)) {
+               if (!list_empty(&cli->cl_cache_waiters)) {
                        CDEBUG(D_CACHE, "cache waiters forcing RPC\n");
                        RETURN(1);
                }
-               if (cfs_atomic_read(&osc->oo_nr_writes) >=
+               if (atomic_read(&osc->oo_nr_writes) >=
                    cli->cl_max_pages_per_rpc)
                        RETURN(1);
        } else {
-               if (cfs_atomic_read(&osc->oo_nr_reads) == 0)
+               if (atomic_read(&osc->oo_nr_reads) == 0)
                        RETURN(0);
                if (invalid_import) {
                        CDEBUG(D_CACHE, "invalid import forcing RPC\n");
                        RETURN(1);
                }
                /* all read are urgent. */
-               if (!cfs_list_empty(&osc->oo_reading_exts))
+               if (!list_empty(&osc->oo_reading_exts))
                        RETURN(1);
        }
 
@@ -1694,28 +1725,29 @@ static void osc_update_pending(struct osc_object *obj, int cmd, int delta)
 {
        struct client_obd *cli = osc_cli(obj);
        if (cmd & OBD_BRW_WRITE) {
-               cfs_atomic_add(delta, &obj->oo_nr_writes);
-               cfs_atomic_add(delta, &cli->cl_pending_w_pages);
-               LASSERT(cfs_atomic_read(&obj->oo_nr_writes) >= 0);
+               atomic_add(delta, &obj->oo_nr_writes);
+               atomic_add(delta, &cli->cl_pending_w_pages);
+               LASSERT(atomic_read(&obj->oo_nr_writes) >= 0);
        } else {
-               cfs_atomic_add(delta, &obj->oo_nr_reads);
-               cfs_atomic_add(delta, &cli->cl_pending_r_pages);
-               LASSERT(cfs_atomic_read(&obj->oo_nr_reads) >= 0);
+               atomic_add(delta, &obj->oo_nr_reads);
+               atomic_add(delta, &cli->cl_pending_r_pages);
+               LASSERT(atomic_read(&obj->oo_nr_reads) >= 0);
        }
        OSC_IO_DEBUG(obj, "update pending cmd %d delta %d.\n", cmd, delta);
 }
 
 static int osc_makes_hprpc(struct osc_object *obj)
 {
-       return !cfs_list_empty(&obj->oo_hp_exts);
+       return !list_empty(&obj->oo_hp_exts);
 }
 
-static void on_list(cfs_list_t *item, cfs_list_t *list, int should_be_on)
+static void on_list(struct list_head *item, struct list_head *list,
+                   int should_be_on)
 {
-       if (cfs_list_empty(item) && should_be_on)
-               cfs_list_add_tail(item, list);
-       else if (!cfs_list_empty(item) && !should_be_on)
-               cfs_list_del_init(item);
+       if (list_empty(item) && should_be_on)
+               list_add_tail(item, list);
+       else if (!list_empty(item) && !should_be_on)
+               list_del_init(item);
 }
 
 /* maintain the osc's cli list membership invariants so that osc_send_oap_rpc
@@ -1734,10 +1766,10 @@ static int __osc_list_maint(struct client_obd *cli, struct osc_object *osc)
        }
 
        on_list(&osc->oo_write_item, &cli->cl_loi_write_list,
-               cfs_atomic_read(&osc->oo_nr_writes) > 0);
+               atomic_read(&osc->oo_nr_writes) > 0);
 
        on_list(&osc->oo_read_item, &cli->cl_loi_read_list,
-               cfs_atomic_read(&osc->oo_nr_reads) > 0);
+               atomic_read(&osc->oo_nr_reads) > 0);
 
        return osc_is_ready(osc);
 }
@@ -1746,9 +1778,9 @@ static int osc_list_maint(struct client_obd *cli, struct osc_object *osc)
 {
        int is_ready;
 
-       client_obd_list_lock(&cli->cl_loi_list_lock);
+       spin_lock(&cli->cl_loi_list_lock);
        is_ready = __osc_list_maint(cli, osc);
-       client_obd_list_unlock(&cli->cl_loi_list_lock);
+       spin_unlock(&cli->cl_loi_list_lock);
 
        return is_ready;
 }
@@ -1798,10 +1830,10 @@ static void osc_ap_completion(const struct lu_env *env, struct client_obd *cli,
        oap->oap_interrupted = 0;
 
        if (oap->oap_cmd & OBD_BRW_WRITE && xid > 0) {
-               client_obd_list_lock(&cli->cl_loi_list_lock);
+               spin_lock(&cli->cl_loi_list_lock);
                osc_process_ar(&cli->cl_ar, xid, rc);
                osc_process_ar(&loi->loi_ar, xid, rc);
-               client_obd_list_unlock(&cli->cl_loi_list_lock);
+               spin_unlock(&cli->cl_loi_list_lock);
        }
 
        rc = osc_completion(env, oap, oap->oap_cmd, rc);
@@ -1818,10 +1850,14 @@ static void osc_ap_completion(const struct lu_env *env, struct client_obd *cli,
  * - extent must be compatible with previous ones
  */
 static int try_to_add_extent_for_io(struct client_obd *cli,
-                                   struct osc_extent *ext, cfs_list_t *rpclist,
-                                   int *pc, unsigned int *max_pages)
+                                   struct osc_extent *ext,
+                                   struct list_head *rpclist,
+                                   unsigned int *pc, unsigned int *max_pages)
 {
        struct osc_extent *tmp;
+       struct osc_async_page *oap = list_first_entry(&ext->oe_pages,
+                                                     struct osc_async_page,
+                                                     oap_pending_item);
        ENTRY;
 
        EASSERT((ext->oe_state == OES_CACHE || ext->oe_state == OES_LOCK_DONE),
@@ -1831,7 +1867,10 @@ static int try_to_add_extent_for_io(struct client_obd *cli,
        if (*pc + ext->oe_nr_pages > *max_pages)
                RETURN(0);
 
-       cfs_list_for_each_entry(tmp, rpclist, oe_link) {
+       list_for_each_entry(tmp, rpclist, oe_link) {
+               struct osc_async_page *oap2;
+               oap2 = list_first_entry(&tmp->oe_pages, struct osc_async_page,
+                                       oap_pending_item);
                EASSERT(tmp->oe_owner == current, tmp);
 #if 0
                if (overlapped(tmp, ext)) {
@@ -1839,6 +1878,11 @@ static int try_to_add_extent_for_io(struct client_obd *cli,
                        EASSERT(0, ext);
                }
 #endif
+               if (oap2cl_page(oap)->cp_type != oap2cl_page(oap2)->cp_type) {
+                       CDEBUG(D_CACHE, "Do not permit different type of IO"
+                                       " for a same RPC\n");
+                       RETURN(0);
+               }
 
                if (tmp->oe_srvlock != ext->oe_srvlock ||
                    !tmp->oe_grants != !ext->oe_grants)
@@ -1849,7 +1893,7 @@ static int try_to_add_extent_for_io(struct client_obd *cli,
        }
 
        *pc += ext->oe_nr_pages;
-       cfs_list_move_tail(&ext->oe_link, rpclist);
+       list_move_tail(&ext->oe_link, rpclist);
        ext->oe_owner = current;
        RETURN(1);
 }
@@ -1867,17 +1911,18 @@ static int try_to_add_extent_for_io(struct client_obd *cli,
  * 5. Traverse the extent tree from the 1st extent;
  * 6. Above steps exit if there is no space in this RPC.
  */
-static int get_write_extents(struct osc_object *obj, cfs_list_t *rpclist)
+static unsigned int get_write_extents(struct osc_object *obj,
+                                     struct list_head *rpclist)
 {
        struct client_obd *cli = osc_cli(obj);
        struct osc_extent *ext;
-       int page_count = 0;
+       unsigned int page_count = 0;
        unsigned int max_pages = cli->cl_max_pages_per_rpc;
 
        LASSERT(osc_object_is_locked(obj));
-       while (!cfs_list_empty(&obj->oo_hp_exts)) {
-               ext = cfs_list_entry(obj->oo_hp_exts.next, struct osc_extent,
-                                    oe_link);
+       while (!list_empty(&obj->oo_hp_exts)) {
+               ext = list_entry(obj->oo_hp_exts.next, struct osc_extent,
+                                oe_link);
                LASSERT(ext->oe_state == OES_CACHE);
                if (!try_to_add_extent_for_io(cli, ext, rpclist, &page_count,
                                              &max_pages))
@@ -1887,9 +1932,9 @@ static int get_write_extents(struct osc_object *obj, cfs_list_t *rpclist)
        if (page_count == max_pages)
                return page_count;
 
-       while (!cfs_list_empty(&obj->oo_urgent_exts)) {
-               ext = cfs_list_entry(obj->oo_urgent_exts.next,
-                                    struct osc_extent, oe_link);
+       while (!list_empty(&obj->oo_urgent_exts)) {
+               ext = list_entry(obj->oo_urgent_exts.next,
+                                struct osc_extent, oe_link);
                if (!try_to_add_extent_for_io(cli, ext, rpclist, &page_count,
                                              &max_pages))
                        return page_count;
@@ -1899,7 +1944,7 @@ static int get_write_extents(struct osc_object *obj, cfs_list_t *rpclist)
 
                while ((ext = next_extent(ext)) != NULL) {
                        if ((ext->oe_state != OES_CACHE) ||
-                           (!cfs_list_empty(&ext->oe_link) &&
+                           (!list_empty(&ext->oe_link) &&
                             ext->oe_owner != NULL))
                                continue;
 
@@ -1915,7 +1960,7 @@ static int get_write_extents(struct osc_object *obj, cfs_list_t *rpclist)
        while (ext != NULL) {
                if ((ext->oe_state != OES_CACHE) ||
                    /* this extent may be already in current rpclist */
-                   (!cfs_list_empty(&ext->oe_link) && ext->oe_owner != NULL)) {
+                   (!list_empty(&ext->oe_link) && ext->oe_owner != NULL)) {
                        ext = next_extent(ext);
                        continue;
                }
@@ -1931,13 +1976,14 @@ static int get_write_extents(struct osc_object *obj, cfs_list_t *rpclist)
 
 static int
 osc_send_write_rpc(const struct lu_env *env, struct client_obd *cli,
-                  struct osc_object *osc, pdl_policy_t pol)
+                  struct osc_object *osc)
+__must_hold(osc)
 {
-       CFS_LIST_HEAD(rpclist);
+       struct list_head   rpclist = LIST_HEAD_INIT(rpclist);
        struct osc_extent *ext;
        struct osc_extent *tmp;
        struct osc_extent *first = NULL;
-       obd_count page_count = 0;
+       unsigned int page_count = 0;
        int srvlock = 0;
        int rc = 0;
        ENTRY;
@@ -1945,14 +1991,14 @@ osc_send_write_rpc(const struct lu_env *env, struct client_obd *cli,
        LASSERT(osc_object_is_locked(osc));
 
        page_count = get_write_extents(osc, &rpclist);
-       LASSERT(equi(page_count == 0, cfs_list_empty(&rpclist)));
+       LASSERT(equi(page_count == 0, list_empty(&rpclist)));
 
-       if (cfs_list_empty(&rpclist))
+       if (list_empty(&rpclist))
                RETURN(0);
 
        osc_update_pending(osc, OBD_BRW_WRITE, -page_count);
 
-       cfs_list_for_each_entry(ext, &rpclist, oe_link) {
+       list_for_each_entry(ext, &rpclist, oe_link) {
                LASSERT(ext->oe_state == OES_CACHE ||
                        ext->oe_state == OES_LOCK_DONE);
                if (ext->oe_state == OES_CACHE)
@@ -1965,11 +2011,11 @@ osc_send_write_rpc(const struct lu_env *env, struct client_obd *cli,
         * lock order is page lock -> object lock. */
        osc_object_unlock(osc);
 
-       cfs_list_for_each_entry_safe(ext, tmp, &rpclist, oe_link) {
+       list_for_each_entry_safe(ext, tmp, &rpclist, oe_link) {
                if (ext->oe_state == OES_LOCKING) {
                        rc = osc_extent_make_ready(env, ext);
                        if (unlikely(rc < 0)) {
-                               cfs_list_del_init(&ext->oe_link);
+                               list_del_init(&ext->oe_link);
                                osc_extent_finish(env, ext, 0, rc);
                                continue;
                        }
@@ -1982,10 +2028,10 @@ osc_send_write_rpc(const struct lu_env *env, struct client_obd *cli,
                }
        }
 
-       if (!cfs_list_empty(&rpclist)) {
+       if (!list_empty(&rpclist)) {
                LASSERT(page_count > 0);
-               rc = osc_build_rpc(env, cli, &rpclist, OBD_BRW_WRITE, pol);
-               LASSERT(cfs_list_empty(&rpclist));
+               rc = osc_build_rpc(env, cli, &rpclist, OBD_BRW_WRITE);
+               LASSERT(list_empty(&rpclist));
        }
 
        osc_object_lock(osc);
@@ -2004,18 +2050,19 @@ osc_send_write_rpc(const struct lu_env *env, struct client_obd *cli,
  */
 static int
 osc_send_read_rpc(const struct lu_env *env, struct client_obd *cli,
-                 struct osc_object *osc, pdl_policy_t pol)
+                 struct osc_object *osc)
+__must_hold(osc)
 {
        struct osc_extent *ext;
        struct osc_extent *next;
-       CFS_LIST_HEAD(rpclist);
-       int page_count = 0;
+       struct list_head rpclist = LIST_HEAD_INIT(rpclist);
+       unsigned int page_count = 0;
        unsigned int max_pages = cli->cl_max_pages_per_rpc;
        int rc = 0;
        ENTRY;
 
        LASSERT(osc_object_is_locked(osc));
-       cfs_list_for_each_entry_safe(ext, next,
+       list_for_each_entry_safe(ext, next,
                                     &osc->oo_reading_exts, oe_link) {
                EASSERT(ext->oe_state == OES_LOCK_DONE, ext);
                if (!try_to_add_extent_for_io(cli, ext, &rpclist, &page_count,
@@ -2028,12 +2075,12 @@ osc_send_read_rpc(const struct lu_env *env, struct client_obd *cli,
 
        osc_update_pending(osc, OBD_BRW_READ, -page_count);
 
-       if (!cfs_list_empty(&rpclist)) {
+       if (!list_empty(&rpclist)) {
                osc_object_unlock(osc);
 
                LASSERT(page_count > 0);
-               rc = osc_build_rpc(env, cli, &rpclist, OBD_BRW_READ, pol);
-               LASSERT(cfs_list_empty(&rpclist));
+               rc = osc_build_rpc(env, cli, &rpclist, OBD_BRW_READ);
+               LASSERT(list_empty(&rpclist));
 
                osc_object_lock(osc);
        }
@@ -2041,9 +2088,9 @@ osc_send_read_rpc(const struct lu_env *env, struct client_obd *cli,
 }
 
 #define list_to_obj(list, item) ({                                           \
-       cfs_list_t *__tmp = (list)->next;                                     \
-       cfs_list_del_init(__tmp);                                             \
-       cfs_list_entry(__tmp, struct osc_object, oo_##item);                  \
+       struct list_head *__tmp = (list)->next;                               \
+       list_del_init(__tmp);                                         \
+       list_entry(__tmp, struct osc_object, oo_##item);                      \
 })
 
 /* This is called by osc_check_rpcs() to find which objects have pages that
@@ -2055,26 +2102,26 @@ static struct osc_object *osc_next_obj(struct client_obd *cli)
        /* First return objects that have blocked locks so that they
         * will be flushed quickly and other clients can get the lock,
         * then objects which have pages ready to be stuffed into RPCs */
-       if (!cfs_list_empty(&cli->cl_loi_hp_ready_list))
+       if (!list_empty(&cli->cl_loi_hp_ready_list))
                RETURN(list_to_obj(&cli->cl_loi_hp_ready_list, hp_ready_item));
-       if (!cfs_list_empty(&cli->cl_loi_ready_list))
+       if (!list_empty(&cli->cl_loi_ready_list))
                RETURN(list_to_obj(&cli->cl_loi_ready_list, ready_item));
 
        /* then if we have cache waiters, return all objects with queued
         * writes.  This is especially important when many small files
         * have filled up the cache and not been fired into rpcs because
         * they don't pass the nr_pending/object threshhold */
-       if (!cfs_list_empty(&cli->cl_cache_waiters) &&
-           !cfs_list_empty(&cli->cl_loi_write_list))
+       if (!list_empty(&cli->cl_cache_waiters) &&
+           !list_empty(&cli->cl_loi_write_list))
                RETURN(list_to_obj(&cli->cl_loi_write_list, write_item));
 
        /* then return all queued objects when we have an invalid import
         * so that they get flushed */
        if (cli->cl_import == NULL || cli->cl_import->imp_invalid) {
-               if (!cfs_list_empty(&cli->cl_loi_write_list))
+               if (!list_empty(&cli->cl_loi_write_list))
                        RETURN(list_to_obj(&cli->cl_loi_write_list,
                                           write_item));
-               if (!cfs_list_empty(&cli->cl_loi_read_list))
+               if (!list_empty(&cli->cl_loi_read_list))
                        RETURN(list_to_obj(&cli->cl_loi_read_list,
                                           read_item));
        }
@@ -2082,8 +2129,8 @@ static struct osc_object *osc_next_obj(struct client_obd *cli)
 }
 
 /* called with the loi list lock held */
-static void osc_check_rpcs(const struct lu_env *env, struct client_obd *cli,
-                          pdl_policy_t pol)
+static void osc_check_rpcs(const struct lu_env *env, struct client_obd *cli)
+__must_hold(&cli->cl_loi_list_lock)
 {
        struct osc_object *osc;
        int rc = 0;
@@ -2101,9 +2148,8 @@ static void osc_check_rpcs(const struct lu_env *env, struct client_obd *cli,
                }
 
                cl_object_get(obj);
-               client_obd_list_unlock(&cli->cl_loi_list_lock);
-               lu_object_ref_add_at(&obj->co_lu, &link, "check",
-                                    current);
+               spin_unlock(&cli->cl_loi_list_lock);
+               lu_object_ref_add_at(&obj->co_lu, &link, "check", current);
 
                /* attempt some read/write balancing by alternating between
                 * reads and writes in an object.  The makes_rpc checks here
@@ -2113,7 +2159,7 @@ static void osc_check_rpcs(const struct lu_env *env, struct client_obd *cli,
                 * do io on writes while there are cache waiters */
                osc_object_lock(osc);
                if (osc_makes_rpc(cli, osc, OBD_BRW_WRITE)) {
-                       rc = osc_send_write_rpc(env, cli, osc, pol);
+                       rc = osc_send_write_rpc(env, cli, osc);
                        if (rc < 0) {
                                CERROR("Write request failed with %d\n", rc);
 
@@ -2137,23 +2183,22 @@ static void osc_check_rpcs(const struct lu_env *env, struct client_obd *cli,
                        }
                }
                if (osc_makes_rpc(cli, osc, OBD_BRW_READ)) {
-                       rc = osc_send_read_rpc(env, cli, osc, pol);
+                       rc = osc_send_read_rpc(env, cli, osc);
                        if (rc < 0)
                                CERROR("Read request failed with %d\n", rc);
                }
                osc_object_unlock(osc);
 
                osc_list_maint(cli, osc);
-               lu_object_ref_del_at(&obj->co_lu, &link, "check",
-                                    current);
+               lu_object_ref_del_at(&obj->co_lu, &link, "check", current);
                cl_object_put(env, obj);
 
-               client_obd_list_lock(&cli->cl_loi_list_lock);
+               spin_lock(&cli->cl_loi_list_lock);
        }
 }
 
 static int osc_io_unplug0(const struct lu_env *env, struct client_obd *cli,
-                         struct osc_object *osc, pdl_policy_t pol, int async)
+                         struct osc_object *osc, int async)
 {
        int rc = 0;
 
@@ -2161,13 +2206,9 @@ static int osc_io_unplug0(const struct lu_env *env, struct client_obd *cli,
                return 0;
 
        if (!async) {
-               /* disable osc_lru_shrink() temporarily to avoid
-                * potential stack overrun problem. LU-2859 */
-               cfs_atomic_inc(&cli->cl_lru_shrinkers);
-               client_obd_list_lock(&cli->cl_loi_list_lock);
-               osc_check_rpcs(env, cli, pol);
-               client_obd_list_unlock(&cli->cl_loi_list_lock);
-               cfs_atomic_dec(&cli->cl_lru_shrinkers);
+               spin_lock(&cli->cl_loi_list_lock);
+               osc_check_rpcs(env, cli);
+               spin_unlock(&cli->cl_loi_list_lock);
        } else {
                CDEBUG(D_CACHE, "Queue writeback work for client %p.\n", cli);
                LASSERT(cli->cl_writeback_work != NULL);
@@ -2179,14 +2220,13 @@ static int osc_io_unplug0(const struct lu_env *env, struct client_obd *cli,
 static int osc_io_unplug_async(const struct lu_env *env,
                                struct client_obd *cli, struct osc_object *osc)
 {
-       /* XXX: policy is no use actually. */
-       return osc_io_unplug0(env, cli, osc, PDL_POLICY_ROUND, 1);
+       return osc_io_unplug0(env, cli, osc, 1);
 }
 
 void osc_io_unplug(const struct lu_env *env, struct client_obd *cli,
-                  struct osc_object *osc, pdl_policy_t pol)
+                  struct osc_object *osc)
 {
-       (void)osc_io_unplug0(env, cli, osc, pol, 0);
+       (void)osc_io_unplug0(env, cli, osc, 0);
 }
 
 int osc_prep_async_page(struct osc_object *osc, struct osc_page *ops,
@@ -2205,13 +2245,13 @@ int osc_prep_async_page(struct osc_object *osc, struct osc_page *ops,
 
        oap->oap_page = page;
        oap->oap_obj_off = offset;
-       LASSERT(!(offset & ~CFS_PAGE_MASK));
+       LASSERT(!(offset & ~PAGE_MASK));
 
        if (!client_is_remote(exp) && cfs_capable(CFS_CAP_SYS_RESOURCE))
                oap->oap_brw_flags = OBD_BRW_NOQUOTA;
 
-       CFS_INIT_LIST_HEAD(&oap->oap_pending_item);
-       CFS_INIT_LIST_HEAD(&oap->oap_rpc_item);
+       INIT_LIST_HEAD(&oap->oap_pending_item);
+       INIT_LIST_HEAD(&oap->oap_rpc_item);
 
        spin_lock_init(&oap->oap_lock);
        CDEBUG(D_INFO, "oap %p page %p obj off "LPU64"\n",
@@ -2228,8 +2268,9 @@ int osc_queue_async_io(const struct lu_env *env, struct cl_io *io,
        struct client_obd     *cli = oap->oap_cli;
        struct osc_object     *osc = oap->oap_obj;
        pgoff_t index;
-       int    grants = 0;
-       int    brw_flags = OBD_BRW_ASYNC;
+       unsigned int tmp;
+       unsigned int grants = 0;
+       u32    brw_flags = OBD_BRW_ASYNC;
        int    cmd = OBD_BRW_WRITE;
        int    need_release = 0;
        int    rc = 0;
@@ -2241,8 +2282,8 @@ int osc_queue_async_io(const struct lu_env *env, struct cl_io *io,
        if (cli->cl_import == NULL || cli->cl_import->imp_invalid)
                RETURN(-EIO);
 
-       if (!cfs_list_empty(&oap->oap_pending_item) ||
-           !cfs_list_empty(&oap->oap_rpc_item))
+       if (!list_empty(&oap->oap_pending_item) ||
+           !list_empty(&oap->oap_rpc_item))
                RETURN(-EBUSY);
 
        /* Set the OBD_BRW_SRVLOCK before the page is queued. */
@@ -2285,7 +2326,7 @@ int osc_queue_async_io(const struct lu_env *env, struct cl_io *io,
        OSC_IO_DEBUG(osc, "oap %p page %p added for cmd %d\n",
                     oap, oap->oap_page, oap->oap_cmd & OBD_BRW_RWMASK);
 
-       index = oap2cl_page(oap)->cp_index;
+       index = osc_index(oap2osc(oap));
 
        /* Add this page into extent by the following steps:
         * 1. if there exists an active extent for this IO, mostly this page
@@ -2302,14 +2343,14 @@ int osc_queue_async_io(const struct lu_env *env, struct cl_io *io,
                        grants = 0;
 
                /* it doesn't need any grant to dirty this page */
-               client_obd_list_lock(&cli->cl_loi_list_lock);
+               spin_lock(&cli->cl_loi_list_lock);
                rc = osc_enter_cache_try(cli, oap, grants, 0);
-               client_obd_list_unlock(&cli->cl_loi_list_lock);
+               spin_unlock(&cli->cl_loi_list_lock);
                if (rc == 0) { /* try failed */
                        grants = 0;
                        need_release = 1;
                } else if (ext->oe_end < index) {
-                       int tmp = grants;
+                       tmp = grants;
                        /* try to expand this extent */
                        rc = osc_extent_expand(ext, index, &tmp);
                        if (rc < 0) {
@@ -2334,7 +2375,7 @@ int osc_queue_async_io(const struct lu_env *env, struct cl_io *io,
        }
 
        if (ext == NULL) {
-               int tmp = (1 << cli->cl_chunkbits) + cli->cl_extent_tax;
+               tmp = (1 << cli->cl_chunkbits) + cli->cl_extent_tax;
 
                /* try to find new extent to cover this page */
                LASSERT(oio->oi_active == NULL);
@@ -2378,7 +2419,7 @@ int osc_queue_async_io(const struct lu_env *env, struct cl_io *io,
                else
                        LASSERT(ext->oe_srvlock == ops->ops_srvlock);
                ++ext->oe_nr_pages;
-               cfs_list_add_tail(&oap->oap_pending_item, &ext->oe_pages);
+               list_add_tail(&oap->oap_pending_item, &ext->oe_pages);
                osc_object_unlock(osc);
        }
        RETURN(rc);
@@ -2388,33 +2429,34 @@ int osc_teardown_async_page(const struct lu_env *env,
                            struct osc_object *obj, struct osc_page *ops)
 {
        struct osc_async_page *oap = &ops->ops_oap;
-       struct osc_extent     *ext = NULL;
        int rc = 0;
        ENTRY;
 
        LASSERT(oap->oap_magic == OAP_MAGIC);
 
        CDEBUG(D_INFO, "teardown oap %p page %p at index %lu.\n",
-              oap, ops, oap2cl_page(oap)->cp_index);
+              oap, ops, osc_index(oap2osc(oap)));
 
-       osc_object_lock(obj);
-       if (!cfs_list_empty(&oap->oap_rpc_item)) {
+       if (!list_empty(&oap->oap_rpc_item)) {
                CDEBUG(D_CACHE, "oap %p is not in cache.\n", oap);
                rc = -EBUSY;
-       } else if (!cfs_list_empty(&oap->oap_pending_item)) {
-               ext = osc_extent_lookup(obj, oap2cl_page(oap)->cp_index);
+       } else if (!list_empty(&oap->oap_pending_item)) {
+               struct osc_extent *ext = NULL;
+
+               osc_object_lock(obj);
+               ext = osc_extent_lookup(obj, osc_index(oap2osc(oap)));
+               osc_object_unlock(obj);
                /* only truncated pages are allowed to be taken out.
                 * See osc_extent_truncate() and osc_cache_truncate_start()
                 * for details. */
                if (ext != NULL && ext->oe_state != OES_TRUNC) {
                        OSC_EXTENT_DUMP(D_ERROR, ext, "trunc at %lu.\n",
-                                       oap2cl_page(oap)->cp_index);
+                                       osc_index(oap2osc(oap)));
                        rc = -EBUSY;
                }
+               if (ext != NULL)
+                       osc_extent_put(env, ext);
        }
-       osc_object_unlock(obj);
-       if (ext != NULL)
-               osc_extent_put(env, ext);
        RETURN(rc);
 }
 
@@ -2431,7 +2473,7 @@ int osc_flush_async_page(const struct lu_env *env, struct cl_io *io,
        struct osc_extent *ext   = NULL;
        struct osc_object *obj   = cl2osc(ops->ops_cl.cpl_obj);
        struct cl_page    *cp    = ops->ops_cl.cpl_page;
-       pgoff_t            index = cp->cp_index;
+       pgoff_t            index = osc_index(ops);
        struct osc_async_page *oap = &ops->ops_oap;
        bool unplug = false;
        int rc = 0;
@@ -2447,8 +2489,7 @@ int osc_flush_async_page(const struct lu_env *env, struct cl_io *io,
        switch (ext->oe_state) {
        case OES_RPC:
        case OES_LOCK_DONE:
-               CL_PAGE_DEBUG(D_ERROR, env, cl_page_top(cp),
-                             "flush an in-rpc page?\n");
+               CL_PAGE_DEBUG(D_ERROR, env, cp, "flush an in-rpc page?\n");
                LASSERT(0);
                break;
        case OES_LOCKING:
@@ -2460,12 +2501,18 @@ int osc_flush_async_page(const struct lu_env *env, struct cl_io *io,
                 * really sending the RPC. */
        case OES_TRUNC:
                /* race with truncate, page will be redirtied */
+       case OES_ACTIVE:
+               /* The extent is active so we need to abort and let the caller
+                * re-dirty the page. If we continued on here, and we were the
+                * one making the extent active, we could deadlock waiting for
+                * the page writeback to clear but it won't because the extent
+                * is active and won't be written out. */
                GOTO(out, rc = -EAGAIN);
        default:
                break;
        }
 
-       rc = cl_page_prep(env, io, cl_page_top(cp), CRT_WRITE);
+       rc = cl_page_prep(env, io, cp, CRT_WRITE);
        if (rc)
                GOTO(out, rc);
 
@@ -2480,8 +2527,8 @@ int osc_flush_async_page(const struct lu_env *env, struct cl_io *io,
        if (ext->oe_state == OES_CACHE) {
                OSC_EXTENT_DUMP(D_CACHE, ext,
                                "flush page %p make it urgent.\n", oap);
-               if (cfs_list_empty(&ext->oe_link))
-                       cfs_list_add_tail(&ext->oe_link, &obj->oo_urgent_exts);
+               if (list_empty(&ext->oe_link))
+                       list_add_tail(&ext->oe_link, &obj->oo_urgent_exts);
                unplug = true;
        }
        rc = 0;
@@ -2509,8 +2556,8 @@ int osc_cancel_async_page(const struct lu_env *env, struct osc_page *ops)
        struct client_obd     *cli = osc_cli(obj);
        struct osc_extent     *ext;
        struct osc_extent     *found = NULL;
-       cfs_list_t            *plist;
-       pgoff_t index = oap2cl_page(oap)->cp_index;
+       struct list_head            *plist;
+       pgoff_t index = osc_index(ops);
        int     rc = -EBUSY;
        int     cmd;
        ENTRY;
@@ -2527,7 +2574,7 @@ int osc_cancel_async_page(const struct lu_env *env, struct osc_page *ops)
                plist = &obj->oo_reading_exts;
                cmd   = OBD_BRW_READ;
        }
-       cfs_list_for_each_entry(ext, plist, oe_link) {
+       list_for_each_entry(ext, plist, oe_link) {
                if (ext->oe_start <= index && ext->oe_end >= index) {
                        LASSERT(ext->oe_state == OES_LOCK_DONE);
                        /* For OES_LOCK_DONE state extent, it has already held
@@ -2537,7 +2584,7 @@ int osc_cancel_async_page(const struct lu_env *env, struct osc_page *ops)
                }
        }
        if (found != NULL) {
-               cfs_list_del_init(&found->oe_link);
+               list_del_init(&found->oe_link);
                osc_update_pending(obj, cmd, -found->oe_nr_pages);
                osc_object_unlock(obj);
 
@@ -2561,7 +2608,7 @@ int osc_cancel_async_page(const struct lu_env *env, struct osc_page *ops)
 }
 
 int osc_queue_sync_pages(const struct lu_env *env, struct osc_object *obj,
-                        cfs_list_t *list, int cmd, int brw_flags)
+                        struct list_head *list, int cmd, int brw_flags)
 {
        struct client_obd     *cli = osc_cli(obj);
        struct osc_extent     *ext;
@@ -2572,26 +2619,29 @@ int osc_queue_sync_pages(const struct lu_env *env, struct osc_object *obj,
        pgoff_t end        = 0;
        ENTRY;
 
-       cfs_list_for_each_entry(oap, list, oap_pending_item) {
-               struct cl_page *cp = oap2cl_page(oap);
-               if (cp->cp_index > end)
-                       end = cp->cp_index;
-               if (cp->cp_index < start)
-                       start = cp->cp_index;
+       list_for_each_entry(oap, list, oap_pending_item) {
+               pgoff_t index = osc_index(oap2osc(oap));
+               if (index > end)
+                       end = index;
+               if (index < start)
+                       start = index;
                ++page_count;
                mppr <<= (page_count > mppr);
        }
 
        ext = osc_extent_alloc(obj);
        if (ext == NULL) {
-               cfs_list_for_each_entry(oap, list, oap_pending_item) {
-                       cfs_list_del_init(&oap->oap_pending_item);
+               struct osc_async_page *tmp;
+
+               list_for_each_entry_safe(oap, tmp, list, oap_pending_item) {
+                       list_del_init(&oap->oap_pending_item);
                        osc_ap_completion(env, cli, oap, 0, -ENOMEM);
                }
                RETURN(-ENOMEM);
        }
 
        ext->oe_rw = !!(cmd & OBD_BRW_READ);
+       ext->oe_sync = 1;
        ext->oe_urgent = 1;
        ext->oe_start = start;
        ext->oe_end = ext->oe_max_end = end;
@@ -2599,35 +2649,35 @@ int osc_queue_sync_pages(const struct lu_env *env, struct osc_object *obj,
        ext->oe_srvlock = !!(brw_flags & OBD_BRW_SRVLOCK);
        ext->oe_nr_pages = page_count;
        ext->oe_mppr = mppr;
-       cfs_list_splice_init(list, &ext->oe_pages);
+       list_splice_init(list, &ext->oe_pages);
 
        osc_object_lock(obj);
        /* Reuse the initial refcount for RPC, don't drop it */
        osc_extent_state_set(ext, OES_LOCK_DONE);
        if (cmd & OBD_BRW_WRITE) {
-               cfs_list_add_tail(&ext->oe_link, &obj->oo_urgent_exts);
+               list_add_tail(&ext->oe_link, &obj->oo_urgent_exts);
                osc_update_pending(obj, OBD_BRW_WRITE, page_count);
        } else {
-               cfs_list_add_tail(&ext->oe_link, &obj->oo_reading_exts);
+               list_add_tail(&ext->oe_link, &obj->oo_reading_exts);
                osc_update_pending(obj, OBD_BRW_READ, page_count);
        }
        osc_object_unlock(obj);
 
-       osc_io_unplug(env, cli, obj, PDL_POLICY_ROUND);
+       osc_io_unplug_async(env, cli, obj);
        RETURN(0);
 }
 
 /**
  * Called by osc_io_setattr_start() to freeze and destroy covering extents.
  */
-int osc_cache_truncate_start(const struct lu_env *env, struct osc_io *oio,
-                            struct osc_object *obj, __u64 size)
+int osc_cache_truncate_start(const struct lu_env *env, struct osc_object *obj,
+                            __u64 size, struct osc_extent **extp)
 {
        struct client_obd *cli = osc_cli(obj);
        struct osc_extent *ext;
        struct osc_extent *waiting = NULL;
        pgoff_t index;
-       CFS_LIST_HEAD(list);
+       struct list_head list = LIST_HEAD_INIT(list);
        int result = 0;
        bool partial;
        ENTRY;
@@ -2674,8 +2724,8 @@ again:
                        osc_update_pending(obj, OBD_BRW_WRITE,
                                           -ext->oe_nr_pages);
                }
-               EASSERT(cfs_list_empty(&ext->oe_link), ext);
-               cfs_list_add_tail(&ext->oe_link, &list);
+               EASSERT(list_empty(&ext->oe_link), ext);
+               list_add_tail(&ext->oe_link, &list);
 
                ext = next_extent(ext);
        }
@@ -2683,11 +2733,11 @@ again:
 
        osc_list_maint(cli, obj);
 
-       while (!cfs_list_empty(&list)) {
+       while (!list_empty(&list)) {
                int rc;
 
-               ext = cfs_list_entry(list.next, struct osc_extent, oe_link);
-               cfs_list_del_init(&ext->oe_link);
+               ext = list_entry(list.next, struct osc_extent, oe_link);
+               list_del_init(&ext->oe_link);
 
                /* extent may be in OES_ACTIVE state because inode mutex
                 * is released before osc_io_end() in file write case */
@@ -2715,9 +2765,11 @@ again:
 
                        /* we need to hold this extent in OES_TRUNC state so
                         * that no writeback will happen. This is to avoid
-                        * BUG 17397. */
-                       LASSERT(oio->oi_trunc == NULL);
-                       oio->oi_trunc = osc_extent_get(ext);
+                        * BUG 17397.
+                        * Only partial truncate can reach here, if @size is
+                        * not zero, the caller should provide a valid @extp. */
+                       LASSERT(*extp == NULL);
+                       *extp = osc_extent_get(ext);
                        OSC_EXTENT_DUMP(D_CACHE, ext,
                                        "trunc at "LPU64"\n", size);
                }
@@ -2742,13 +2794,10 @@ again:
 /**
  * Called after osc_io_setattr_end to add oio->oi_trunc back to cache.
  */
-void osc_cache_truncate_end(const struct lu_env *env, struct osc_io *oio,
-                           struct osc_object *obj)
+void osc_cache_truncate_end(const struct lu_env *env, struct osc_extent *ext)
 {
-       struct osc_extent *ext = oio->oi_trunc;
-
-       oio->oi_trunc = NULL;
        if (ext != NULL) {
+               struct osc_object *obj = ext->oe_obj;
                bool unplug = false;
 
                EASSERT(ext->oe_nr_pages > 0, ext);
@@ -2760,7 +2809,7 @@ void osc_cache_truncate_end(const struct lu_env *env, struct osc_io *oio,
                osc_extent_state_set(ext, OES_CACHE);
                if (ext->oe_fsync_wait && !ext->oe_urgent) {
                        ext->oe_urgent = 1;
-                       cfs_list_move_tail(&ext->oe_link, &obj->oo_urgent_exts);
+                       list_move_tail(&ext->oe_link, &obj->oo_urgent_exts);
                        unplug = true;
                }
                osc_update_pending(obj, OBD_BRW_WRITE, ext->oe_nr_pages);
@@ -2841,7 +2890,7 @@ int osc_cache_writeback_range(const struct lu_env *env, struct osc_object *obj,
                              pgoff_t start, pgoff_t end, int hp, int discard)
 {
        struct osc_extent *ext;
-       CFS_LIST_HEAD(discard_list);
+       struct list_head discard_list = LIST_HEAD_INIT(discard_list);
        bool unplug = false;
        int result = 0;
        ENTRY;
@@ -2861,7 +2910,7 @@ int osc_cache_writeback_range(const struct lu_env *env, struct osc_object *obj,
                case OES_CACHE:
                        result += ext->oe_nr_pages;
                        if (!discard) {
-                               cfs_list_t *list = NULL;
+                               struct list_head *list = NULL;
                                if (hp) {
                                        EASSERT(!ext->oe_hp, ext);
                                        ext->oe_hp = 1;
@@ -2871,7 +2920,7 @@ int osc_cache_writeback_range(const struct lu_env *env, struct osc_object *obj,
                                        list = &obj->oo_urgent_exts;
                                }
                                if (list != NULL)
-                                       cfs_list_move_tail(&ext->oe_link, list);
+                                       list_move_tail(&ext->oe_link, list);
                                unplug = true;
                        } else {
                                /* the only discarder is lock cancelling, so
@@ -2880,7 +2929,7 @@ int osc_cache_writeback_range(const struct lu_env *env, struct osc_object *obj,
                                        ext->oe_max_end <= end, ext);
                                osc_extent_state_set(ext, OES_LOCKING);
                                ext->oe_owner = current;
-                               cfs_list_move_tail(&ext->oe_link,
+                               list_move_tail(&ext->oe_link,
                                                   &discard_list);
                                osc_update_pending(obj, OBD_BRW_WRITE,
                                                   -ext->oe_nr_pages);
@@ -2905,14 +2954,14 @@ int osc_cache_writeback_range(const struct lu_env *env, struct osc_object *obj,
        }
        osc_object_unlock(obj);
 
-       LASSERT(ergo(!discard, cfs_list_empty(&discard_list)));
-       if (!cfs_list_empty(&discard_list)) {
+       LASSERT(ergo(!discard, list_empty(&discard_list)));
+       if (!list_empty(&discard_list)) {
                struct osc_extent *tmp;
                int rc;
 
                osc_list_maint(osc_cli(obj), obj);
-               cfs_list_for_each_entry_safe(ext, tmp, &discard_list, oe_link) {
-                       cfs_list_del_init(&ext->oe_link);
+               list_for_each_entry_safe(ext, tmp, &discard_list, oe_link) {
+                       list_del_init(&ext->oe_link);
                        EASSERT(ext->oe_state == OES_LOCKING, ext);
 
                        /* Discard caching pages. We don't actually write this
@@ -2931,7 +2980,7 @@ int osc_cache_writeback_range(const struct lu_env *env, struct osc_object *obj,
        }
 
        if (unplug)
-               osc_io_unplug(env, osc_cli(obj), obj, PDL_POLICY_ROUND);
+               osc_io_unplug(env, osc_cli(obj), obj);
 
        if (hp || discard) {
                int rc;
@@ -2944,4 +2993,203 @@ int osc_cache_writeback_range(const struct lu_env *env, struct osc_object *obj,
        RETURN(result);
 }
 
+/**
+ * Returns a list of pages by a given [start, end] of \a obj.
+ *
+ * \param resched If not NULL, then we give up before hogging CPU for too
+ * long and set *resched = 1, in that case caller should implement a retry
+ * logic.
+ *
+ * Gang tree lookup (radix_tree_gang_lookup()) optimization is absolutely
+ * crucial in the face of [offset, EOF] locks.
+ *
+ * Return at least one page in @queue unless there is no covered page.
+ */
+int osc_page_gang_lookup(const struct lu_env *env, struct cl_io *io,
+                       struct osc_object *osc, pgoff_t start, pgoff_t end,
+                       osc_page_gang_cbt cb, void *cbdata)
+{
+       struct osc_page *ops;
+       void            **pvec;
+       pgoff_t         idx;
+       unsigned int    nr;
+       unsigned int    i;
+       unsigned int    j;
+       int             res = CLP_GANG_OKAY;
+       bool            tree_lock = true;
+       ENTRY;
+
+       idx = start;
+       pvec = osc_env_info(env)->oti_pvec;
+       spin_lock(&osc->oo_tree_lock);
+       while ((nr = radix_tree_gang_lookup(&osc->oo_tree, pvec,
+                                           idx, OTI_PVEC_SIZE)) > 0) {
+               struct cl_page *page;
+               bool end_of_region = false;
+
+               for (i = 0, j = 0; i < nr; ++i) {
+                       ops = pvec[i];
+                       pvec[i] = NULL;
+
+                       idx = osc_index(ops);
+                       if (idx > end) {
+                               end_of_region = true;
+                               break;
+                       }
+
+                       page = ops->ops_cl.cpl_page;
+                       LASSERT(page->cp_type == CPT_CACHEABLE);
+                       if (page->cp_state == CPS_FREEING)
+                               continue;
+
+                       cl_page_get(page);
+                       lu_ref_add_atomic(&page->cp_reference,
+                                         "gang_lookup", current);
+                       pvec[j++] = ops;
+               }
+               ++idx;
+
+               /*
+                * Here a delicate locking dance is performed. Current thread
+                * holds a reference to a page, but has to own it before it
+                * can be placed into queue. Owning implies waiting, so
+                * radix-tree lock is to be released. After a wait one has to
+                * check that pages weren't truncated (cl_page_own() returns
+                * error in the latter case).
+                */
+               spin_unlock(&osc->oo_tree_lock);
+               tree_lock = false;
+
+               for (i = 0; i < j; ++i) {
+                       ops = pvec[i];
+                       if (res == CLP_GANG_OKAY)
+                               res = (*cb)(env, io, ops, cbdata);
+
+                       page = ops->ops_cl.cpl_page;
+                       lu_ref_del(&page->cp_reference, "gang_lookup", current);
+                       cl_page_put(env, page);
+               }
+               if (nr < OTI_PVEC_SIZE || end_of_region)
+                       break;
+
+               if (res == CLP_GANG_OKAY && need_resched())
+                       res = CLP_GANG_RESCHED;
+               if (res != CLP_GANG_OKAY)
+                       break;
+
+               spin_lock(&osc->oo_tree_lock);
+               tree_lock = true;
+       }
+       if (tree_lock)
+               spin_unlock(&osc->oo_tree_lock);
+       RETURN(res);
+}
+
+/**
+ * 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 osc_page *ops, void *cbdata)
+{
+       struct osc_thread_info *info = osc_env_info(env);
+       struct osc_object *osc = cbdata;
+       pgoff_t index;
+
+       index = osc_index(ops);
+       if (index >= info->oti_fn_index) {
+               struct ldlm_lock *tmp;
+               struct cl_page *page = ops->ops_cl.cpl_page;
+
+               /* refresh non-overlapped index */
+               tmp = osc_dlmlock_at_pgoff(env, osc, index,
+                                          OSC_DAP_FL_TEST_LOCK);
+               if (tmp != NULL) {
+                       __u64 end = tmp->l_policy_data.l_extent.end;
+                       /* Cache the first-non-overlapped index so as to skip
+                        * all pages within [index, oti_fn_index). This is safe
+                        * because if tmp lock is canceled, it will discard
+                        * these pages. */
+                       info->oti_fn_index = cl_index(osc2cl(osc), end + 1);
+                       if (end == OBD_OBJECT_EOF)
+                               info->oti_fn_index = CL_PAGE_EOF;
+                       LDLM_LOCK_PUT(tmp);
+               } else if (cl_page_own(env, io, page) == 0) {
+                       /* discard the page */
+                       cl_page_discard(env, io, page);
+                       cl_page_disown(env, io, page);
+               } else {
+                       LASSERT(page->cp_state == CPS_FREEING);
+               }
+       }
+
+       info->oti_next_index = index + 1;
+       return CLP_GANG_OKAY;
+}
+
+static int discard_cb(const struct lu_env *env, struct cl_io *io,
+                     struct osc_page *ops, void *cbdata)
+{
+       struct osc_thread_info *info = osc_env_info(env);
+       struct cl_page *page = ops->ops_cl.cpl_page;
+
+       /* page is top page. */
+       info->oti_next_index = osc_index(ops) + 1;
+       if (cl_page_own(env, io, page) == 0) {
+               if (!ergo(page->cp_type == CPT_CACHEABLE,
+                         !PageDirty(cl_page_vmpage(page))))
+                       CL_PAGE_DEBUG(D_ERROR, env, page,
+                                       "discard dirty page?\n");
+
+               /* discard the page */
+               cl_page_discard(env, io, page);
+               cl_page_disown(env, io, page);
+       } else {
+               LASSERT(page->cp_state == CPS_FREEING);
+       }
+
+       return CLP_GANG_OKAY;
+}
+
+/**
+ * Discard pages protected by the given lock. This function traverses radix
+ * tree to find all covering pages and discard them. If a page is being covered
+ * by other locks, it should remain in cache.
+ *
+ * If error happens on any step, the process continues anyway (the reasoning
+ * behind this being that lock cancellation cannot be delayed indefinitely).
+ */
+int osc_lock_discard_pages(const struct lu_env *env, struct osc_object *osc,
+                          pgoff_t start, pgoff_t end, enum cl_lock_mode mode)
+{
+       struct osc_thread_info *info = osc_env_info(env);
+       struct cl_io *io = &info->oti_io;
+       osc_page_gang_cbt cb;
+       int res;
+       int result;
+
+       ENTRY;
+
+       io->ci_obj = cl_object_top(osc2cl(osc));
+       io->ci_ignore_layout = 1;
+       result = cl_io_init(env, io, CIT_MISC, io->ci_obj);
+       if (result != 0)
+               GOTO(out, result);
+
+       cb = mode == CLM_READ ? check_and_discard_cb : discard_cb;
+       info->oti_fn_index = info->oti_next_index = start;
+       do {
+               res = osc_page_gang_lookup(env, io, osc,
+                                          info->oti_next_index, end, cb, osc);
+               if (info->oti_next_index > end)
+                       break;
+
+               if (res == CLP_GANG_RESCHED)
+                       cond_resched();
+       } while (res != CLP_GANG_OKAY);
+out:
+       cl_io_fini(env, io);
+       RETURN(result);
+}
+
+
 /** @} osc */