lustre/osc/osc_page.c

   1 /* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
   2  * vim:expandtab:shiftwidth=8:tabstop=8:
   3  *
   4  * GPL HEADER START
   5  *
   6  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 only,
  10  * as published by the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope that it will be useful, but
  13  * WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * General Public License version 2 for more details (a copy is included
  16  * in the LICENSE file that accompanied this code).
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * version 2 along with this program; If not, see
  20  * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
  21  *
  22  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  23  * CA 95054 USA or visit www.sun.com if you need additional information or
  24  * have any questions.
  25  *
  26  * GPL HEADER END
  27  */
  28 /*
  29  * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  30  * Use is subject to license terms.
  31  *
  32  * Copyright (c) 2011 Whamcloud, Inc.
  33  *
  34  */
  35 /*
  36  * This file is part of Lustre, http://www.lustre.org/
  37  * Lustre is a trademark of Sun Microsystems, Inc.
  38  *
  39  * Implementation of cl_page for OSC layer.
  40  *
  41  *   Author: Nikita Danilov <nikita.danilov@sun.com>
  42  */
  43
  44 #define DEBUG_SUBSYSTEM S_OSC
  45
  46 #include "osc_cl_internal.h"
  47
  48 /** \addtogroup osc
  49  *  @{
  50  */
  51
  52 /*
  53  * Comment out osc_page_protected because it may sleep inside the
  54  * the client_obd_list_lock.
  55  * client_obd_list_lock -> osc_ap_completion -> osc_completion ->
  56  *   -> osc_page_protected -> osc_page_is_dlocked -> osc_match_base
  57  *   -> ldlm_lock_match -> sptlrpc_import_check_ctx -> sleep.
  58  */
  59 #if 0
  60 static int osc_page_is_dlocked(const struct lu_env *env,
  61                                const struct osc_page *opg,
  62                                enum cl_lock_mode mode, int pending, int unref)
  63 {
  64         struct cl_page         *page;
  65         struct osc_object      *obj;
  66         struct osc_thread_info *info;
  67         struct ldlm_res_id     *resname;
  68         struct lustre_handle   *lockh;
  69         ldlm_policy_data_t     *policy;
  70         ldlm_mode_t             dlmmode;
  71         int                     flags;
  72
  73         cfs_might_sleep();
  74
  75         info = osc_env_info(env);
  76         resname = &info->oti_resname;
  77         policy = &info->oti_policy;
  78         lockh = &info->oti_handle;
  79         page = opg->ops_cl.cpl_page;
  80         obj = cl2osc(opg->ops_cl.cpl_obj);
  81
  82         flags = LDLM_FL_TEST_LOCK | LDLM_FL_BLOCK_GRANTED;
  83         if (pending)
  84                 flags |= LDLM_FL_CBPENDING;
  85
  86         dlmmode = osc_cl_lock2ldlm(mode) | LCK_PW;
  87         osc_lock_build_res(env, obj, resname);
  88         osc_index2policy(policy, page->cp_obj, page->cp_index, page->cp_index);
  89         return osc_match_base(osc_export(obj), resname, LDLM_EXTENT, policy,
  90                               dlmmode, &flags, NULL, lockh, unref);
  91 }
  92
  93 /**
  94  * Checks an invariant that a page in the cache is covered by a lock, as
  95  * needed.
  96  */
  97 static int osc_page_protected(const struct lu_env *env,
  98                               const struct osc_page *opg,
  99                               enum cl_lock_mode mode, int unref)
 100 {
 101         struct cl_object_header *hdr;
 102         struct cl_lock          *scan;
 103         struct cl_page          *page;
 104         struct cl_lock_descr    *descr;
 105         int result;
 106
 107         LINVRNT(!opg->ops_temp);
 108
 109         page = opg->ops_cl.cpl_page;
 110         if (page->cp_owner != NULL &&
 111             cl_io_top(page->cp_owner)->ci_lockreq == CILR_NEVER)
 112                 /*
 113                  * If IO is done without locks (liblustre, or lloop), lock is
 114                  * not required.
 115                  */
 116                 result = 1;
 117         else
 118                 /* otherwise check for a DLM lock */
 119         result = osc_page_is_dlocked(env, opg, mode, 1, unref);
 120         if (result == 0) {
 121                 /* maybe this page is a part of a lockless io? */
 122                 hdr = cl_object_header(opg->ops_cl.cpl_obj);
 123                 descr = &osc_env_info(env)->oti_descr;
 124                 descr->cld_mode = mode;
 125                 descr->cld_start = page->cp_index;
 126                 descr->cld_end   = page->cp_index;
 127                 cfs_spin_lock(&hdr->coh_lock_guard);
 128                 cfs_list_for_each_entry(scan, &hdr->coh_locks, cll_linkage) {
 129                         /*
 130                          * Lock-less sub-lock has to be either in HELD state
 131                          * (when io is actively going on), or in CACHED state,
 132                          * when top-lock is being unlocked:
 133                          * cl_io_unlock()->cl_unuse()->...->lov_lock_unuse().
 134                          */
 135                         if ((scan->cll_state == CLS_HELD ||
 136                              scan->cll_state == CLS_CACHED) &&
 137                             cl_lock_ext_match(&scan->cll_descr, descr)) {
 138                                 struct osc_lock *olck;
 139
 140                                 olck = osc_lock_at(scan);
 141                                 result = osc_lock_is_lockless(olck);
 142                                 break;
 143                         }
 144                 }
 145                 cfs_spin_unlock(&hdr->coh_lock_guard);
 146         }
 147         return result;
 148 }
 149 #else
 150 static int osc_page_protected(const struct lu_env *env,
 151                               const struct osc_page *opg,
 152                               enum cl_lock_mode mode, int unref)
 153 {
 154         return 1;
 155 }
 156 #endif
 157
 158 /*****************************************************************************
 159  *
 160  * Page operations.
 161  *
 162  */
 163 static void osc_page_fini(const struct lu_env *env,
 164                           struct cl_page_slice *slice)
 165 {
 166         struct osc_page *opg = cl2osc_page(slice);
 167         CDEBUG(D_TRACE, "%p\n", opg);
 168         LASSERT(opg->ops_lock == NULL);
 169         OBD_SLAB_FREE_PTR(opg, osc_page_kmem);
 170 }
 171
 172 static void osc_page_transfer_get(struct osc_page *opg, const char *label)
 173 {
 174         struct cl_page *page = cl_page_top(opg->ops_cl.cpl_page);
 175
 176         LASSERT(!opg->ops_transfer_pinned);
 177         cl_page_get(page);
 178         lu_ref_add_atomic(&page->cp_reference, label, page);
 179         opg->ops_transfer_pinned = 1;
 180 }
 181
 182 static void osc_page_transfer_put(const struct lu_env *env,
 183                                   struct osc_page *opg)
 184 {
 185         struct cl_page *page = cl_page_top(opg->ops_cl.cpl_page);
 186
 187         if (opg->ops_transfer_pinned) {
 188                 lu_ref_del(&page->cp_reference, "transfer", page);
 189                 opg->ops_transfer_pinned = 0;
 190                 cl_page_put(env, page);
 191         }
 192 }
 193
 194 /**
 195  * This is called once for every page when it is submitted for a transfer
 196  * either opportunistic (osc_page_cache_add()), or immediate
 197  * (osc_page_submit()).
 198  */
 199 static void osc_page_transfer_add(const struct lu_env *env,
 200                                   struct osc_page *opg, enum cl_req_type crt)
 201 {
 202         struct osc_object *obj;
 203
 204         LINVRNT(cl_page_is_vmlocked(env, opg->ops_cl.cpl_page));
 205
 206         obj = cl2osc(opg->ops_cl.cpl_obj);
 207         cfs_spin_lock(&obj->oo_seatbelt);
 208         cfs_list_add(&opg->ops_inflight, &obj->oo_inflight[crt]);
 209         opg->ops_submitter = cfs_current();
 210         cfs_spin_unlock(&obj->oo_seatbelt);
 211 }
 212
 213 static int osc_page_cache_add(const struct lu_env *env,
 214                               const struct cl_page_slice *slice,
 215                               struct cl_io *unused)
 216 {
 217         struct osc_page   *opg = cl2osc_page(slice);
 218         struct osc_object *obj = cl2osc(opg->ops_cl.cpl_obj);
 219         int result;
 220         /* All cacheable IO is async-capable */
 221         int brw_flags = OBD_BRW_ASYNC;
 222         int noquota = 0;
 223
 224         LINVRNT(osc_page_protected(env, opg, CLM_WRITE, 0));
 225         ENTRY;
 226
 227         /* Set the OBD_BRW_SRVLOCK before the page is queued. */
 228         brw_flags |= opg->ops_srvlock ? OBD_BRW_SRVLOCK : 0;
 229         if (!client_is_remote(osc_export(obj)) &&
 230             cfs_capable(CFS_CAP_SYS_RESOURCE)) {
 231                 brw_flags |= OBD_BRW_NOQUOTA;
 232                 noquota = OBD_BRW_NOQUOTA;
 233         }
 234
 235         osc_page_transfer_get(opg, "transfer\0cache");
 236         result = osc_queue_async_io(env, osc_export(obj), NULL, obj->oo_oinfo,
 237                                     &opg->ops_oap, OBD_BRW_WRITE | noquota,
 238                                     opg->ops_from, opg->ops_to - opg->ops_from,
 239                                     brw_flags, 0);
 240         if (result != 0)
 241                 osc_page_transfer_put(env, opg);
 242         else
 243                 osc_page_transfer_add(env, opg, CRT_WRITE);
 244         RETURN(result);
 245 }
 246
 247 void osc_index2policy(ldlm_policy_data_t *policy, const struct cl_object *obj,
 248                       pgoff_t start, pgoff_t end)
 249 {
 250         memset(policy, 0, sizeof *policy);
 251         policy->l_extent.start = cl_offset(obj, start);
 252         policy->l_extent.end   = cl_offset(obj, end + 1) - 1;
 253 }
 254
 255 static int osc_page_addref_lock(const struct lu_env *env,
 256                                 struct osc_page *opg,
 257                                 struct cl_lock *lock)
 258 {
 259         struct osc_lock *olock;
 260         int              rc;
 261
 262         LASSERT(opg->ops_lock == NULL);
 263
 264         olock = osc_lock_at(lock);
 265         if (cfs_atomic_inc_return(&olock->ols_pageref) <= 0) {
 266                 cfs_atomic_dec(&olock->ols_pageref);
 267                 cl_lock_put(env, lock);
 268                 rc = 1;
 269         } else {
 270                 opg->ops_lock = lock;
 271                 rc = 0;
 272         }
 273         return rc;
 274 }
 275
 276 static void osc_page_putref_lock(const struct lu_env *env,
 277                                  struct osc_page *opg)
 278 {
 279         struct cl_lock  *lock = opg->ops_lock;
 280         struct osc_lock *olock;
 281
 282         LASSERT(lock != NULL);
 283         olock = osc_lock_at(lock);
 284
 285         cfs_atomic_dec(&olock->ols_pageref);
 286         opg->ops_lock = NULL;
 287
 288         /*
 289          * Note: usually this won't be the last reference of the lock, but if
 290          * it is, then all the lock_put do is at most just freeing some memory,
 291          * so it would be OK that caller is holding spinlocks.
 292          */
 293         LASSERT(cfs_atomic_read(&lock->cll_ref) > 1 || olock->ols_hold == 0);
 294         cl_lock_put(env, lock);
 295 }
 296
 297 static int osc_page_is_under_lock(const struct lu_env *env,
 298                                   const struct cl_page_slice *slice,
 299                                   struct cl_io *unused)
 300 {
 301         struct cl_lock *lock;
 302         int             result;
 303
 304         ENTRY;
 305         lock = cl_lock_at_page(env, slice->cpl_obj, slice->cpl_page,
 306                                NULL, 1, 0);
 307         if (lock != NULL &&
 308             osc_page_addref_lock(env, cl2osc_page(slice), lock) == 0)
 309                 result = -EBUSY;
 310         else
 311                 result = -ENODATA;
 312         RETURN(result);
 313 }
 314
 315 static void osc_page_disown(const struct lu_env *env,
 316                             const struct cl_page_slice *slice,
 317                             struct cl_io *io)
 318 {
 319         struct osc_page *opg = cl2osc_page(slice);
 320
 321         if (unlikely(opg->ops_lock))
 322                 osc_page_putref_lock(env, opg);
 323 }
 324
 325 static void osc_page_completion_read(const struct lu_env *env,
 326                                      const struct cl_page_slice *slice,
 327                                      int ioret)
 328 {
 329         struct osc_page *opg = cl2osc_page(slice);
 330
 331         if (likely(opg->ops_lock))
 332                 osc_page_putref_lock(env, opg);
 333 }
 334
 335 static int osc_page_fail(const struct lu_env *env,
 336                          const struct cl_page_slice *slice,
 337                          struct cl_io *unused)
 338 {
 339         /*
 340          * Cached read?
 341          */
 342         LBUG();
 343         return 0;
 344 }
 345
 346
 347 static const char *osc_list(cfs_list_t *head)
 348 {
 349         return cfs_list_empty(head) ? "-" : "+";
 350 }
 351
 352 static inline cfs_time_t osc_submit_duration(struct osc_page *opg)
 353 {
 354         if (opg->ops_submit_time == 0)
 355                 return 0;
 356
 357         return (cfs_time_current() - opg->ops_submit_time);
 358 }
 359
 360 static int osc_page_print(const struct lu_env *env,
 361                           const struct cl_page_slice *slice,
 362                           void *cookie, lu_printer_t printer)
 363 {
 364         struct osc_page       *opg = cl2osc_page(slice);
 365         struct osc_async_page *oap = &opg->ops_oap;
 366         struct osc_object     *obj = cl2osc(slice->cpl_obj);
 367         struct client_obd     *cli = &osc_export(obj)->exp_obd->u.cli;
 368         struct lov_oinfo      *loi = obj->oo_oinfo;
 369
 370         return (*printer)(env, cookie, LUSTRE_OSC_NAME"-page@%p: "
 371                           "1< %#x %d %u %s %s %s > "
 372                           "2< "LPU64" %u %u %#x %#x | %p %p %p %p %p > "
 373                           "3< %s %p %d %lu %d > "
 374                           "4< %d %d %d %lu %s | %s %s %s %s > "
 375                           "5< %s %s %s %s | %d %s %s | %d %s %s>\n",
 376                           opg,
 377                           /* 1 */
 378                           oap->oap_magic, oap->oap_cmd,
 379                           oap->oap_interrupted,
 380                           osc_list(&oap->oap_pending_item),
 381                           osc_list(&oap->oap_urgent_item),
 382                           osc_list(&oap->oap_rpc_item),
 383                           /* 2 */
 384                           oap->oap_obj_off, oap->oap_page_off, oap->oap_count,
 385                           oap->oap_async_flags, oap->oap_brw_flags,
 386                           oap->oap_request,
 387                           oap->oap_cli, oap->oap_loi, oap->oap_caller_ops,
 388                           oap->oap_caller_data,
 389                           /* 3 */
 390                           osc_list(&opg->ops_inflight),
 391                           opg->ops_submitter, opg->ops_transfer_pinned,
 392                           osc_submit_duration(opg), opg->ops_srvlock,
 393                           /* 4 */
 394                           cli->cl_r_in_flight, cli->cl_w_in_flight,
 395                           cli->cl_max_rpcs_in_flight,
 396                           cli->cl_avail_grant,
 397                           osc_list(&cli->cl_cache_waiters),
 398                           osc_list(&cli->cl_loi_ready_list),
 399                           osc_list(&cli->cl_loi_hp_ready_list),
 400                           osc_list(&cli->cl_loi_write_list),
 401                           osc_list(&cli->cl_loi_read_list),
 402                           /* 5 */
 403                           osc_list(&loi->loi_ready_item),
 404                           osc_list(&loi->loi_hp_ready_item),
 405                           osc_list(&loi->loi_write_item),
 406                           osc_list(&loi->loi_read_item),
 407                           loi->loi_read_lop.lop_num_pending,
 408                           osc_list(&loi->loi_read_lop.lop_pending),
 409                           osc_list(&loi->loi_read_lop.lop_urgent),
 410                           loi->loi_write_lop.lop_num_pending,
 411                           osc_list(&loi->loi_write_lop.lop_pending),
 412                           osc_list(&loi->loi_write_lop.lop_urgent));
 413 }
 414
 415 static void osc_page_delete(const struct lu_env *env,
 416                             const struct cl_page_slice *slice)
 417 {
 418         struct osc_page       *opg = cl2osc_page(slice);
 419         struct osc_object     *obj = cl2osc(opg->ops_cl.cpl_obj);
 420         struct osc_async_page *oap = &opg->ops_oap;
 421         int rc;
 422
 423         LINVRNT(opg->ops_temp || osc_page_protected(env, opg, CLM_READ, 1));
 424
 425         ENTRY;
 426         CDEBUG(D_TRACE, "%p\n", opg);
 427         osc_page_transfer_put(env, opg);
 428         rc = osc_teardown_async_page(osc_export(obj), NULL, obj->oo_oinfo, oap);
 429         if (rc) {
 430                 CL_PAGE_DEBUG(D_ERROR, env, cl_page_top(slice->cpl_page),
 431                               "Trying to teardown failed: %d\n", rc);
 432                 LASSERT(0);
 433         }
 434         cfs_spin_lock(&obj->oo_seatbelt);
 435         cfs_list_del_init(&opg->ops_inflight);
 436         cfs_spin_unlock(&obj->oo_seatbelt);
 437         EXIT;
 438 }
 439
 440 void osc_page_clip(const struct lu_env *env, const struct cl_page_slice *slice,
 441                    int from, int to)
 442 {
 443         struct osc_page       *opg = cl2osc_page(slice);
 444         struct osc_async_page *oap = &opg->ops_oap;
 445
 446         LINVRNT(osc_page_protected(env, opg, CLM_READ, 0));
 447
 448         opg->ops_from = from;
 449         opg->ops_to   = to;
 450         cfs_spin_lock(&oap->oap_lock);
 451         oap->oap_async_flags |= ASYNC_COUNT_STABLE;
 452         cfs_spin_unlock(&oap->oap_lock);
 453 }
 454
 455 static int osc_page_cancel(const struct lu_env *env,
 456                            const struct cl_page_slice *slice)
 457 {
 458         struct osc_page *opg       = cl2osc_page(slice);
 459         struct osc_async_page *oap = &opg->ops_oap;
 460         int rc = 0;
 461
 462         LINVRNT(osc_page_protected(env, opg, CLM_READ, 0));
 463
 464         client_obd_list_lock(&oap->oap_cli->cl_loi_list_lock);
 465         /* Check if the transferring against this page
 466          * is completed, or not even queued. */
 467         if (opg->ops_transfer_pinned)
 468                 /* FIXME: may not be interrupted.. */
 469                 rc = osc_oap_interrupted(env, oap);
 470         LASSERT(ergo(rc == 0, opg->ops_transfer_pinned == 0));
 471         client_obd_list_unlock(&oap->oap_cli->cl_loi_list_lock);
 472         return rc;
 473 }
 474
 475 static const struct cl_page_operations osc_page_ops = {
 476         .cpo_fini          = osc_page_fini,
 477         .cpo_print         = osc_page_print,
 478         .cpo_delete        = osc_page_delete,
 479         .cpo_is_under_lock = osc_page_is_under_lock,
 480         .cpo_disown        = osc_page_disown,
 481         .io = {
 482                 [CRT_READ] = {
 483                         .cpo_cache_add  = osc_page_fail,
 484                         .cpo_completion = osc_page_completion_read
 485                 },
 486                 [CRT_WRITE] = {
 487                         .cpo_cache_add  = osc_page_cache_add
 488                 }
 489         },
 490         .cpo_clip           = osc_page_clip,
 491         .cpo_cancel         = osc_page_cancel
 492 };
 493
 494 static int osc_make_ready(const struct lu_env *env, void *data, int cmd)
 495 {
 496         struct osc_page *opg  = data;
 497         struct cl_page  *page = cl_page_top(opg->ops_cl.cpl_page);
 498         int result;
 499
 500         LASSERT(cmd == OBD_BRW_WRITE); /* no cached reads */
 501         LINVRNT(osc_page_protected(env, opg, CLM_WRITE, 1));
 502
 503         ENTRY;
 504         result = cl_page_make_ready(env, page, CRT_WRITE);
 505         if (result == 0)
 506                 opg->ops_submit_time = cfs_time_current();
 507         RETURN(result);
 508 }
 509
 510 static int osc_refresh_count(const struct lu_env *env, void *data, int cmd)
 511 {
 512         struct cl_page   *page;
 513         struct osc_page  *osc = data;
 514         struct cl_object *obj;
 515         struct cl_attr   *attr = &osc_env_info(env)->oti_attr;
 516
 517         int result;
 518         loff_t kms;
 519
 520         LINVRNT(osc_page_protected(env, osc, CLM_READ, 1));
 521
 522         /* readpage queues with _COUNT_STABLE, shouldn't get here. */
 523         LASSERT(!(cmd & OBD_BRW_READ));
 524         LASSERT(osc != NULL);
 525         page = osc->ops_cl.cpl_page;
 526         obj = osc->ops_cl.cpl_obj;
 527
 528         cl_object_attr_lock(obj);
 529         result = cl_object_attr_get(env, obj, attr);
 530         cl_object_attr_unlock(obj);
 531         if (result < 0)
 532                 return result;
 533         kms = attr->cat_kms;
 534         if (cl_offset(obj, page->cp_index) >= kms)
 535                 /* catch race with truncate */
 536                 return 0;
 537         else if (cl_offset(obj, page->cp_index + 1) > kms)
 538                 /* catch sub-page write at end of file */
 539                 return kms % CFS_PAGE_SIZE;
 540         else
 541                 return CFS_PAGE_SIZE;
 542 }
 543
 544 static int osc_completion(const struct lu_env *env,
 545                           void *data, int cmd, struct obdo *oa, int rc)
 546 {
 547         struct osc_page       *opg  = data;
 548         struct osc_async_page *oap  = &opg->ops_oap;
 549         struct cl_page        *page = cl_page_top(opg->ops_cl.cpl_page);
 550         struct osc_object     *obj  = cl2osc(opg->ops_cl.cpl_obj);
 551         enum cl_req_type crt;
 552
 553         LINVRNT(osc_page_protected(env, opg, CLM_READ, 1));
 554         LINVRNT(cl_page_is_vmlocked(env, page));
 555
 556         ENTRY;
 557
 558         cmd &= ~OBD_BRW_NOQUOTA;
 559         LASSERT(equi(page->cp_state == CPS_PAGEIN,  cmd == OBD_BRW_READ));
 560         LASSERT(equi(page->cp_state == CPS_PAGEOUT, cmd == OBD_BRW_WRITE));
 561         LASSERT(opg->ops_transfer_pinned);
 562
 563         /*
 564          * page->cp_req can be NULL if io submission failed before
 565          * cl_req was allocated.
 566          */
 567         if (page->cp_req != NULL)
 568                 cl_req_page_done(env, page);
 569         LASSERT(page->cp_req == NULL);
 570
 571         /* As the transfer for this page is being done, clear the flags */
 572         cfs_spin_lock(&oap->oap_lock);
 573         oap->oap_async_flags = 0;
 574         cfs_spin_unlock(&oap->oap_lock);
 575
 576         crt = cmd == OBD_BRW_READ ? CRT_READ : CRT_WRITE;
 577         /* Clear opg->ops_transfer_pinned before VM lock is released. */
 578         opg->ops_transfer_pinned = 0;
 579
 580         cfs_spin_lock(&obj->oo_seatbelt);
 581         LASSERT(opg->ops_submitter != NULL);
 582         LASSERT(!cfs_list_empty(&opg->ops_inflight));
 583         cfs_list_del_init(&opg->ops_inflight);
 584         cfs_spin_unlock(&obj->oo_seatbelt);
 585
 586         opg->ops_submit_time = 0;
 587
 588         cl_page_completion(env, page, crt, rc);
 589
 590         /* statistic */
 591         if (rc == 0 && oap->oap_brw_flags & OBD_BRW_SRVLOCK) {
 592                 struct lu_device *ld    = opg->ops_cl.cpl_obj->co_lu.lo_dev;
 593                 struct osc_stats *stats = &lu2osc_dev(ld)->od_stats;
 594                 int bytes = oap->oap_count;
 595
 596                 if (crt == CRT_READ)
 597                         stats->os_lockless_reads += bytes;
 598                 else
 599                         stats->os_lockless_writes += bytes;
 600         }
 601
 602         /*
 603          * This has to be the last operation with the page, as locks are
 604          * released in cl_page_completion() and nothing except for the
 605          * reference counter protects page from concurrent reclaim.
 606          */
 607         lu_ref_del(&page->cp_reference, "transfer", page);
 608         /*
 609          * As page->cp_obj is pinned by a reference from page->cp_req, it is
 610          * safe to call cl_page_put() without risking object destruction in a
 611          * non-blocking context.
 612          */
 613         cl_page_put(env, page);
 614         RETURN(0);
 615 }
 616
 617 const static struct obd_async_page_ops osc_async_page_ops = {
 618         .ap_make_ready    = osc_make_ready,
 619         .ap_refresh_count = osc_refresh_count,
 620         .ap_completion    = osc_completion
 621 };
 622
 623 struct cl_page *osc_page_init(const struct lu_env *env,
 624                               struct cl_object *obj,
 625                               struct cl_page *page, cfs_page_t *vmpage)
 626 {
 627         struct osc_object *osc = cl2osc(obj);
 628         struct osc_page   *opg;
 629         int result;
 630
 631         OBD_SLAB_ALLOC_PTR_GFP(opg, osc_page_kmem, CFS_ALLOC_IO);
 632         if (opg != NULL) {
 633                 void *oap = &opg->ops_oap;
 634
 635                 opg->ops_from = 0;
 636                 opg->ops_to   = CFS_PAGE_SIZE;
 637
 638                 result = osc_prep_async_page(osc_export(osc),
 639                                              NULL, osc->oo_oinfo, vmpage,
 640                                              cl_offset(obj, page->cp_index),
 641                                              &osc_async_page_ops,
 642                                              opg, (void **)&oap, 1, NULL);
 643                 if (result == 0) {
 644                         struct osc_io *oio = osc_env_io(env);
 645                         opg->ops_srvlock = osc_io_srvlock(oio);
 646                         cl_page_slice_add(page, &opg->ops_cl, obj,
 647                                           &osc_page_ops);
 648                 }
 649                 /*
 650                  * Cannot assert osc_page_protected() here as read-ahead
 651                  * creates temporary pages outside of a lock.
 652                  */
 653 #ifdef INVARIANT_CHECK
 654                 opg->ops_temp = !osc_page_protected(env, opg, CLM_READ, 1);
 655 #endif
 656                 CFS_INIT_LIST_HEAD(&opg->ops_inflight);
 657         } else
 658                 result = -ENOMEM;
 659         return ERR_PTR(result);
 660 }
 661
 662 /**
 663  * Helper function called by osc_io_submit() for every page in an immediate
 664  * transfer (i.e., transferred synchronously).
 665  */
 666 void osc_io_submit_page(const struct lu_env *env,
 667                         struct osc_io *oio, struct osc_page *opg,
 668                         enum cl_req_type crt)
 669 {
 670         struct osc_async_page *oap = &opg->ops_oap;
 671         struct client_obd     *cli = oap->oap_cli;
 672         int flags = 0;
 673
 674         LINVRNT(osc_page_protected(env, opg,
 675                                    crt == CRT_WRITE ? CLM_WRITE : CLM_READ, 1));
 676
 677         oap->oap_page_off   = opg->ops_from;
 678         oap->oap_count      = opg->ops_to - opg->ops_from;
 679         /* Give a hint to OST that requests are coming from kswapd - bug19529 */
 680         if (cfs_memory_pressure_get())
 681                 oap->oap_brw_flags |= OBD_BRW_MEMALLOC;
 682         oap->oap_brw_flags |= OBD_BRW_SYNC;
 683         if (osc_io_srvlock(oio))
 684                 oap->oap_brw_flags |= OBD_BRW_SRVLOCK;
 685
 686         oap->oap_cmd = crt == CRT_WRITE ? OBD_BRW_WRITE : OBD_BRW_READ;
 687         if (!client_is_remote(osc_export(cl2osc(opg->ops_cl.cpl_obj))) &&
 688             cfs_capable(CFS_CAP_SYS_RESOURCE)) {
 689                 oap->oap_brw_flags |= OBD_BRW_NOQUOTA;
 690                 oap->oap_cmd |= OBD_BRW_NOQUOTA;
 691         }
 692
 693         if (oap->oap_cmd & OBD_BRW_READ)
 694                 flags = ASYNC_COUNT_STABLE;
 695         else if (!(oap->oap_brw_page.flag & OBD_BRW_FROM_GRANT))
 696                 osc_enter_cache_try(env, cli, oap->oap_loi, oap, 1);
 697
 698         cfs_spin_lock(&oap->oap_lock);
 699         oap->oap_async_flags |= OSC_FLAGS | flags;
 700         cfs_spin_unlock(&oap->oap_lock);
 701
 702         osc_oap_to_pending(oap);
 703         osc_page_transfer_get(opg, "transfer\0imm");
 704         osc_page_transfer_add(env, opg, crt);
 705 }
 706
 707 /** @} osc */