lustre/osc/osc_page.c

   1 /*
   2  * GPL HEADER START
   3  *
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 only,
   8  * as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License version 2 for more details (a copy is included
  14  * in the LICENSE file that accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * version 2 along with this program; If not, see
  18  * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
  19  *
  20  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  21  * CA 95054 USA or visit www.sun.com if you need additional information or
  22  * have any questions.
  23  *
  24  * GPL HEADER END
  25  */
  26 /*
  27  * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  28  * Use is subject to license terms.
  29  *
  30  * Copyright (c) 2011, Whamcloud, Inc.
  31  */
  32 /*
  33  * This file is part of Lustre, http://www.lustre.org/
  34  * Lustre is a trademark of Sun Microsystems, Inc.
  35  *
  36  * Implementation of cl_page for OSC layer.
  37  *
  38  *   Author: Nikita Danilov <nikita.danilov@sun.com>
  39  */
  40
  41 #define DEBUG_SUBSYSTEM S_OSC
  42
  43 #include "osc_cl_internal.h"
  44
  45 static void osc_lru_del(struct client_obd *cli, struct osc_page *opg, bool del);
  46 static void osc_lru_add(struct client_obd *cli, struct osc_page *opg);
  47 static int osc_lru_reserve(const struct lu_env *env, struct osc_object *obj,
  48                            struct osc_page *opg);
  49
  50 /** \addtogroup osc
  51  *  @{
  52  */
  53
  54 /*
  55  * Comment out osc_page_protected because it may sleep inside the
  56  * the client_obd_list_lock.
  57  * client_obd_list_lock -> osc_ap_completion -> osc_completion ->
  58  *   -> osc_page_protected -> osc_page_is_dlocked -> osc_match_base
  59  *   -> ldlm_lock_match -> sptlrpc_import_check_ctx -> sleep.
  60  */
  61 #if 0
  62 static int osc_page_is_dlocked(const struct lu_env *env,
  63                                const struct osc_page *opg,
  64                                enum cl_lock_mode mode, int pending, int unref)
  65 {
  66         struct cl_page         *page;
  67         struct osc_object      *obj;
  68         struct osc_thread_info *info;
  69         struct ldlm_res_id     *resname;
  70         struct lustre_handle   *lockh;
  71         ldlm_policy_data_t     *policy;
  72         ldlm_mode_t             dlmmode;
  73         int                     flags;
  74
  75         cfs_might_sleep();
  76
  77         info = osc_env_info(env);
  78         resname = &info->oti_resname;
  79         policy = &info->oti_policy;
  80         lockh = &info->oti_handle;
  81         page = opg->ops_cl.cpl_page;
  82         obj = cl2osc(opg->ops_cl.cpl_obj);
  83
  84         flags = LDLM_FL_TEST_LOCK | LDLM_FL_BLOCK_GRANTED;
  85         if (pending)
  86                 flags |= LDLM_FL_CBPENDING;
  87
  88         dlmmode = osc_cl_lock2ldlm(mode) | LCK_PW;
  89         osc_lock_build_res(env, obj, resname);
  90         osc_index2policy(policy, page->cp_obj, page->cp_index, page->cp_index);
  91         return osc_match_base(osc_export(obj), resname, LDLM_EXTENT, policy,
  92                               dlmmode, &flags, NULL, lockh, unref);
  93 }
  94
  95 /**
  96  * Checks an invariant that a page in the cache is covered by a lock, as
  97  * needed.
  98  */
  99 static int osc_page_protected(const struct lu_env *env,
 100                               const struct osc_page *opg,
 101                               enum cl_lock_mode mode, int unref)
 102 {
 103         struct cl_object_header *hdr;
 104         struct cl_lock          *scan;
 105         struct cl_page          *page;
 106         struct cl_lock_descr    *descr;
 107         int result;
 108
 109         LINVRNT(!opg->ops_temp);
 110
 111         page = opg->ops_cl.cpl_page;
 112         if (page->cp_owner != NULL &&
 113             cl_io_top(page->cp_owner)->ci_lockreq == CILR_NEVER)
 114                 /*
 115                  * If IO is done without locks (liblustre, or lloop), lock is
 116                  * not required.
 117                  */
 118                 result = 1;
 119         else
 120                 /* otherwise check for a DLM lock */
 121         result = osc_page_is_dlocked(env, opg, mode, 1, unref);
 122         if (result == 0) {
 123                 /* maybe this page is a part of a lockless io? */
 124                 hdr = cl_object_header(opg->ops_cl.cpl_obj);
 125                 descr = &osc_env_info(env)->oti_descr;
 126                 descr->cld_mode = mode;
 127                 descr->cld_start = page->cp_index;
 128                 descr->cld_end   = page->cp_index;
 129                 spin_lock(&hdr->coh_lock_guard);
 130                 cfs_list_for_each_entry(scan, &hdr->coh_locks, cll_linkage) {
 131                         /*
 132                          * Lock-less sub-lock has to be either in HELD state
 133                          * (when io is actively going on), or in CACHED state,
 134                          * when top-lock is being unlocked:
 135                          * cl_io_unlock()->cl_unuse()->...->lov_lock_unuse().
 136                          */
 137                         if ((scan->cll_state == CLS_HELD ||
 138                              scan->cll_state == CLS_CACHED) &&
 139                             cl_lock_ext_match(&scan->cll_descr, descr)) {
 140                                 struct osc_lock *olck;
 141
 142                                 olck = osc_lock_at(scan);
 143                                 result = osc_lock_is_lockless(olck);
 144                                 break;
 145                         }
 146                 }
 147                 spin_unlock(&hdr->coh_lock_guard);
 148         }
 149         return result;
 150 }
 151 #else
 152 static int osc_page_protected(const struct lu_env *env,
 153                               const struct osc_page *opg,
 154                               enum cl_lock_mode mode, int unref)
 155 {
 156         return 1;
 157 }
 158 #endif
 159
 160 /*****************************************************************************
 161  *
 162  * Page operations.
 163  *
 164  */
 165 static void osc_page_fini(const struct lu_env *env,
 166                           struct cl_page_slice *slice)
 167 {
 168         struct osc_page *opg = cl2osc_page(slice);
 169         CDEBUG(D_TRACE, "%p\n", opg);
 170         LASSERT(opg->ops_lock == NULL);
 171         OBD_SLAB_FREE_PTR(opg, osc_page_kmem);
 172 }
 173
 174 static void osc_page_transfer_get(struct osc_page *opg, const char *label)
 175 {
 176         struct cl_page *page = cl_page_top(opg->ops_cl.cpl_page);
 177
 178         LASSERT(!opg->ops_transfer_pinned);
 179         cl_page_get(page);
 180         lu_ref_add_atomic(&page->cp_reference, label, page);
 181         opg->ops_transfer_pinned = 1;
 182 }
 183
 184 static void osc_page_transfer_put(const struct lu_env *env,
 185                                   struct osc_page *opg)
 186 {
 187         struct cl_page *page = cl_page_top(opg->ops_cl.cpl_page);
 188
 189         if (opg->ops_transfer_pinned) {
 190                 lu_ref_del(&page->cp_reference, "transfer", page);
 191                 opg->ops_transfer_pinned = 0;
 192                 cl_page_put(env, page);
 193         }
 194 }
 195
 196 /**
 197  * This is called once for every page when it is submitted for a transfer
 198  * either opportunistic (osc_page_cache_add()), or immediate
 199  * (osc_page_submit()).
 200  */
 201 static void osc_page_transfer_add(const struct lu_env *env,
 202                                   struct osc_page *opg, enum cl_req_type crt)
 203 {
 204         struct osc_object *obj = cl2osc(opg->ops_cl.cpl_obj);
 205
 206         /* ops_lru and ops_inflight share the same field, so take it from LRU
 207          * first and then use it as inflight. */
 208         osc_lru_del(osc_cli(obj), opg, false);
 209
 210         spin_lock(&obj->oo_seatbelt);
 211         cfs_list_add(&opg->ops_inflight, &obj->oo_inflight[crt]);
 212         opg->ops_submitter = cfs_current();
 213         spin_unlock(&obj->oo_seatbelt);
 214 }
 215
 216 static int osc_page_cache_add(const struct lu_env *env,
 217                               const struct cl_page_slice *slice,
 218                               struct cl_io *io)
 219 {
 220         struct osc_io   *oio = osc_env_io(env);
 221         struct osc_page *opg = cl2osc_page(slice);
 222         int result;
 223         ENTRY;
 224
 225         LINVRNT(osc_page_protected(env, opg, CLM_WRITE, 0));
 226
 227         osc_page_transfer_get(opg, "transfer\0cache");
 228         result = osc_queue_async_io(env, io, opg);
 229         if (result != 0)
 230                 osc_page_transfer_put(env, opg);
 231         else
 232                 osc_page_transfer_add(env, opg, CRT_WRITE);
 233
 234         /* for sync write, kernel will wait for this page to be flushed before
 235          * osc_io_end() is called, so release it earlier.
 236          * for mkwrite(), it's known there is no further pages. */
 237         if (cl_io_is_sync_write(io) || cl_io_is_mkwrite(io)) {
 238                 if (oio->oi_active != NULL) {
 239                         osc_extent_release(env, oio->oi_active);
 240                         oio->oi_active = NULL;
 241                 }
 242         }
 243
 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                 rc = -ENODATA;
 268         } else {
 269                 cl_lock_get(lock);
 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         cl_lock_put(env, lock);
 289 }
 290
 291 static int osc_page_is_under_lock(const struct lu_env *env,
 292                                   const struct cl_page_slice *slice,
 293                                   struct cl_io *unused)
 294 {
 295         struct cl_lock *lock;
 296         int             result = -ENODATA;
 297
 298         ENTRY;
 299         lock = cl_lock_at_page(env, slice->cpl_obj, slice->cpl_page,
 300                                NULL, 1, 0);
 301         if (lock != NULL) {
 302                 if (osc_page_addref_lock(env, cl2osc_page(slice), lock) == 0)
 303                         result = -EBUSY;
 304                 cl_lock_put(env, lock);
 305         }
 306         RETURN(result);
 307 }
 308
 309 static void osc_page_disown(const struct lu_env *env,
 310                             const struct cl_page_slice *slice,
 311                             struct cl_io *io)
 312 {
 313         struct osc_page *opg = cl2osc_page(slice);
 314
 315         if (unlikely(opg->ops_lock))
 316                 osc_page_putref_lock(env, opg);
 317 }
 318
 319 static void osc_page_completion_read(const struct lu_env *env,
 320                                      const struct cl_page_slice *slice,
 321                                      int ioret)
 322 {
 323         struct osc_page   *opg = cl2osc_page(slice);
 324         struct osc_object *obj = cl2osc(opg->ops_cl.cpl_obj);
 325
 326         if (likely(opg->ops_lock))
 327                 osc_page_putref_lock(env, opg);
 328         osc_lru_add(osc_cli(obj), opg);
 329 }
 330
 331 static void osc_page_completion_write(const struct lu_env *env,
 332                                       const struct cl_page_slice *slice,
 333                                       int ioret)
 334 {
 335         struct osc_page   *opg = cl2osc_page(slice);
 336         struct osc_object *obj = cl2osc(slice->cpl_obj);
 337
 338         osc_lru_add(osc_cli(obj), opg);
 339 }
 340
 341 static int osc_page_fail(const struct lu_env *env,
 342                          const struct cl_page_slice *slice,
 343                          struct cl_io *unused)
 344 {
 345         /*
 346          * Cached read?
 347          */
 348         LBUG();
 349         return 0;
 350 }
 351
 352
 353 static const char *osc_list(cfs_list_t *head)
 354 {
 355         return cfs_list_empty(head) ? "-" : "+";
 356 }
 357
 358 static inline cfs_time_t osc_submit_duration(struct osc_page *opg)
 359 {
 360         if (opg->ops_submit_time == 0)
 361                 return 0;
 362
 363         return (cfs_time_current() - opg->ops_submit_time);
 364 }
 365
 366 static int osc_page_print(const struct lu_env *env,
 367                           const struct cl_page_slice *slice,
 368                           void *cookie, lu_printer_t printer)
 369 {
 370         struct osc_page       *opg = cl2osc_page(slice);
 371         struct osc_async_page *oap = &opg->ops_oap;
 372         struct osc_object     *obj = cl2osc(slice->cpl_obj);
 373         struct client_obd     *cli = &osc_export(obj)->exp_obd->u.cli;
 374
 375         return (*printer)(env, cookie, LUSTRE_OSC_NAME"-page@%p: "
 376                           "1< %#x %d %u %s %s > "
 377                           "2< "LPU64" %u %u %#x %#x | %p %p %p > "
 378                           "3< %s %p %d %lu %d > "
 379                           "4< %d %d %d %lu %s | %s %s %s %s > "
 380                           "5< %s %s %s %s | %d %s | %d %s %s>\n",
 381                           opg,
 382                           /* 1 */
 383                           oap->oap_magic, oap->oap_cmd,
 384                           oap->oap_interrupted,
 385                           osc_list(&oap->oap_pending_item),
 386                           osc_list(&oap->oap_rpc_item),
 387                           /* 2 */
 388                           oap->oap_obj_off, oap->oap_page_off, oap->oap_count,
 389                           oap->oap_async_flags, oap->oap_brw_flags,
 390                           oap->oap_request, oap->oap_cli, obj,
 391                           /* 3 */
 392                           osc_list(&opg->ops_inflight),
 393                           opg->ops_submitter, opg->ops_transfer_pinned,
 394                           osc_submit_duration(opg), opg->ops_srvlock,
 395                           /* 4 */
 396                           cli->cl_r_in_flight, cli->cl_w_in_flight,
 397                           cli->cl_max_rpcs_in_flight,
 398                           cli->cl_avail_grant,
 399                           osc_list(&cli->cl_cache_waiters),
 400                           osc_list(&cli->cl_loi_ready_list),
 401                           osc_list(&cli->cl_loi_hp_ready_list),
 402                           osc_list(&cli->cl_loi_write_list),
 403                           osc_list(&cli->cl_loi_read_list),
 404                           /* 5 */
 405                           osc_list(&obj->oo_ready_item),
 406                           osc_list(&obj->oo_hp_ready_item),
 407                           osc_list(&obj->oo_write_item),
 408                           osc_list(&obj->oo_read_item),
 409                           cfs_atomic_read(&obj->oo_nr_reads),
 410                           osc_list(&obj->oo_reading_exts),
 411                           cfs_atomic_read(&obj->oo_nr_writes),
 412                           osc_list(&obj->oo_hp_exts),
 413                           osc_list(&obj->oo_urgent_exts));
 414 }
 415
 416 static void osc_page_delete(const struct lu_env *env,
 417                             const struct cl_page_slice *slice)
 418 {
 419         struct osc_page   *opg = cl2osc_page(slice);
 420         struct osc_object *obj = cl2osc(opg->ops_cl.cpl_obj);
 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(env, obj, opg);
 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
 435         spin_lock(&obj->oo_seatbelt);
 436         if (opg->ops_submitter != NULL) {
 437                 LASSERT(!cfs_list_empty(&opg->ops_inflight));
 438                 cfs_list_del_init(&opg->ops_inflight);
 439                 opg->ops_submitter = NULL;
 440         }
 441         spin_unlock(&obj->oo_seatbelt);
 442
 443         osc_lru_del(osc_cli(obj), opg, true);
 444         EXIT;
 445 }
 446
 447 void osc_page_clip(const struct lu_env *env, const struct cl_page_slice *slice,
 448                    int from, int to)
 449 {
 450         struct osc_page       *opg = cl2osc_page(slice);
 451         struct osc_async_page *oap = &opg->ops_oap;
 452
 453         LINVRNT(osc_page_protected(env, opg, CLM_READ, 0));
 454
 455         opg->ops_from = from;
 456         opg->ops_to   = to;
 457         spin_lock(&oap->oap_lock);
 458         oap->oap_async_flags |= ASYNC_COUNT_STABLE;
 459         spin_unlock(&oap->oap_lock);
 460 }
 461
 462 static int osc_page_cancel(const struct lu_env *env,
 463                            const struct cl_page_slice *slice)
 464 {
 465         struct osc_page *opg = cl2osc_page(slice);
 466         int rc = 0;
 467
 468         LINVRNT(osc_page_protected(env, opg, CLM_READ, 0));
 469
 470         /* Check if the transferring against this page
 471          * is completed, or not even queued. */
 472         if (opg->ops_transfer_pinned)
 473                 /* FIXME: may not be interrupted.. */
 474                 rc = osc_cancel_async_page(env, opg);
 475         LASSERT(ergo(rc == 0, opg->ops_transfer_pinned == 0));
 476         return rc;
 477 }
 478
 479 static int osc_page_flush(const struct lu_env *env,
 480                           const struct cl_page_slice *slice,
 481                           struct cl_io *io)
 482 {
 483         struct osc_page *opg = cl2osc_page(slice);
 484         int rc = 0;
 485         ENTRY;
 486         rc = osc_flush_async_page(env, io, opg);
 487         RETURN(rc);
 488 }
 489
 490 static const struct cl_page_operations osc_page_ops = {
 491         .cpo_fini          = osc_page_fini,
 492         .cpo_print         = osc_page_print,
 493         .cpo_delete        = osc_page_delete,
 494         .cpo_is_under_lock = osc_page_is_under_lock,
 495         .cpo_disown        = osc_page_disown,
 496         .io = {
 497                 [CRT_READ] = {
 498                         .cpo_cache_add  = osc_page_fail,
 499                         .cpo_completion = osc_page_completion_read
 500                 },
 501                 [CRT_WRITE] = {
 502                         .cpo_cache_add  = osc_page_cache_add,
 503                         .cpo_completion = osc_page_completion_write
 504                 }
 505         },
 506         .cpo_clip           = osc_page_clip,
 507         .cpo_cancel         = osc_page_cancel,
 508         .cpo_flush          = osc_page_flush
 509 };
 510
 511 struct cl_page *osc_page_init(const struct lu_env *env,
 512                               struct cl_object *obj,
 513                               struct cl_page *page, cfs_page_t *vmpage)
 514 {
 515         struct osc_object *osc = cl2osc(obj);
 516         struct osc_page   *opg;
 517         int result;
 518
 519         OBD_SLAB_ALLOC_PTR_GFP(opg, osc_page_kmem, CFS_ALLOC_IO);
 520         if (opg != NULL) {
 521                 opg->ops_from = 0;
 522                 opg->ops_to   = CFS_PAGE_SIZE;
 523
 524                 result = osc_prep_async_page(osc, opg, vmpage,
 525                                              cl_offset(obj, page->cp_index));
 526                 if (result == 0) {
 527                         struct osc_io *oio = osc_env_io(env);
 528                         opg->ops_srvlock = osc_io_srvlock(oio);
 529                         cl_page_slice_add(page, &opg->ops_cl, obj,
 530                                           &osc_page_ops);
 531                 }
 532                 /*
 533                  * Cannot assert osc_page_protected() here as read-ahead
 534                  * creates temporary pages outside of a lock.
 535                  */
 536 #ifdef INVARIANT_CHECK
 537                 opg->ops_temp = !osc_page_protected(env, opg, CLM_READ, 1);
 538 #endif
 539                 /* ops_inflight and ops_lru are the same field, but it doesn't
 540                  * hurt to initialize it twice :-) */
 541                 CFS_INIT_LIST_HEAD(&opg->ops_inflight);
 542                 CFS_INIT_LIST_HEAD(&opg->ops_lru);
 543         } else
 544                 result = -ENOMEM;
 545
 546         /* reserve an LRU space for this page */
 547         if (page->cp_type == CPT_CACHEABLE && result == 0)
 548                 result = osc_lru_reserve(env, osc, opg);
 549
 550         return ERR_PTR(result);
 551 }
 552
 553 /**
 554  * Helper function called by osc_io_submit() for every page in an immediate
 555  * transfer (i.e., transferred synchronously).
 556  */
 557 void osc_page_submit(const struct lu_env *env, struct osc_page *opg,
 558                      enum cl_req_type crt, int brw_flags)
 559 {
 560         struct osc_async_page *oap = &opg->ops_oap;
 561         struct osc_object     *obj = oap->oap_obj;
 562
 563         LINVRNT(osc_page_protected(env, opg,
 564                                    crt == CRT_WRITE ? CLM_WRITE : CLM_READ, 1));
 565
 566         LASSERTF(oap->oap_magic == OAP_MAGIC, "Bad oap magic: oap %p, "
 567                  "magic 0x%x\n", oap, oap->oap_magic);
 568         LASSERT(oap->oap_async_flags & ASYNC_READY);
 569         LASSERT(oap->oap_async_flags & ASYNC_COUNT_STABLE);
 570
 571         oap->oap_cmd       = crt == CRT_WRITE ? OBD_BRW_WRITE : OBD_BRW_READ;
 572         oap->oap_page_off  = opg->ops_from;
 573         oap->oap_count     = opg->ops_to - opg->ops_from;
 574         oap->oap_brw_flags = OBD_BRW_SYNC | brw_flags;
 575
 576         if (!client_is_remote(osc_export(obj)) &&
 577                         cfs_capable(CFS_CAP_SYS_RESOURCE)) {
 578                 oap->oap_brw_flags |= OBD_BRW_NOQUOTA;
 579                 oap->oap_cmd |= OBD_BRW_NOQUOTA;
 580         }
 581
 582         opg->ops_submit_time = cfs_time_current();
 583         osc_page_transfer_get(opg, "transfer\0imm");
 584         osc_page_transfer_add(env, opg, crt);
 585 }
 586
 587 /* --------------- LRU page management ------------------ */
 588
 589 /* OSC is a natural place to manage LRU pages as applications are specialized
 590  * to write OSC by OSC. Ideally, if one OSC is used more frequently it should
 591  * occupy more LRU slots. On the other hand, we should avoid using up all LRU
 592  * slots (client_obd::cl_lru_left) otherwise process has to be put into sleep
 593  * for free LRU slots - this will be very bad so the algorithm requires each
 594  * OSC to free slots voluntarily to maintain a reasonable number of free slots
 595  * at any time.
 596  */
 597
 598 static CFS_DECL_WAITQ(osc_lru_waitq);
 599 static cfs_atomic_t osc_lru_waiters = CFS_ATOMIC_INIT(0);
 600 /* LRU pages are freed in batch mode. OSC should at least free this
 601  * number of pages to avoid running out of LRU budget, and.. */
 602 static const int lru_shrink_min = 2 << (20 - CFS_PAGE_SHIFT);  /* 2M */
 603 /* free this number at most otherwise it will take too long time to finsih. */
 604 static const int lru_shrink_max = 32 << (20 - CFS_PAGE_SHIFT); /* 32M */
 605
 606 /* Check if we can free LRU slots from this OSC. If there exists LRU waiters,
 607  * we should free slots aggressively. In this way, slots are freed in a steady
 608  * step to maintain fairness among OSCs.
 609  *
 610  * Return how many LRU pages should be freed. */
 611 static int osc_cache_too_much(struct client_obd *cli)
 612 {
 613         struct cl_client_cache *cache = cli->cl_cache;
 614         int pages = cfs_atomic_read(&cli->cl_lru_in_list) >> 1;
 615
 616         if (cfs_atomic_read(&osc_lru_waiters) > 0 &&
 617             cfs_atomic_read(cli->cl_lru_left) < lru_shrink_max)
 618                 /* drop lru pages aggressively */
 619                 return min(pages, lru_shrink_max);
 620
 621         /* if it's going to run out LRU slots, we should free some, but not
 622          * too much to maintain faireness among OSCs. */
 623         if (cfs_atomic_read(cli->cl_lru_left) < cache->ccc_lru_max >> 4) {
 624                 unsigned long tmp;
 625
 626                 tmp = cache->ccc_lru_max / cfs_atomic_read(&cache->ccc_users);
 627                 if (pages > tmp)
 628                         return min(pages, lru_shrink_max);
 629
 630                 return pages > lru_shrink_min ? lru_shrink_min : 0;
 631         }
 632
 633         return 0;
 634 }
 635
 636 /* Return how many pages are not discarded in @pvec. */
 637 static int discard_pagevec(const struct lu_env *env, struct cl_io *io,
 638                            struct cl_page **pvec, int max_index)
 639 {
 640         int count;
 641         int i;
 642
 643         for (count = 0, i = 0; i < max_index; i++) {
 644                 struct cl_page *page = pvec[i];
 645                 if (cl_page_own_try(env, io, page) == 0) {
 646                         /* free LRU page only if nobody is using it.
 647                          * This check is necessary to avoid freeing the pages
 648                          * having already been removed from LRU and pinned
 649                          * for IO. */
 650                         if (cfs_atomic_read(&page->cp_ref) == 1) {
 651                                 cl_page_unmap(env, io, page);
 652                                 cl_page_discard(env, io, page);
 653                                 ++count;
 654                         }
 655                         cl_page_disown(env, io, page);
 656                 }
 657                 cl_page_put(env, page);
 658                 pvec[i] = NULL;
 659         }
 660         return max_index - count;
 661 }
 662
 663 /**
 664  * Drop @target of pages from LRU at most.
 665  */
 666 int osc_lru_shrink(struct client_obd *cli, int target)
 667 {
 668         struct cl_env_nest nest;
 669         struct lu_env *env;
 670         struct cl_io *io;
 671         struct cl_object *clobj = NULL;
 672         struct cl_page **pvec;
 673         struct osc_page *opg;
 674         int maxscan = 0;
 675         int count = 0;
 676         int index = 0;
 677         int rc = 0;
 678         ENTRY;
 679
 680         LASSERT(cfs_atomic_read(&cli->cl_lru_in_list) >= 0);
 681         if (cfs_atomic_read(&cli->cl_lru_in_list) == 0 || target <= 0)
 682                 RETURN(0);
 683
 684         env = cl_env_nested_get(&nest);
 685         if (IS_ERR(env))
 686                 RETURN(PTR_ERR(env));
 687
 688         pvec = osc_env_info(env)->oti_pvec;
 689         io = &osc_env_info(env)->oti_io;
 690
 691         client_obd_list_lock(&cli->cl_lru_list_lock);
 692         cfs_atomic_inc(&cli->cl_lru_shrinkers);
 693         maxscan = min(target << 1, cfs_atomic_read(&cli->cl_lru_in_list));
 694         while (!cfs_list_empty(&cli->cl_lru_list)) {
 695                 struct cl_page *page;
 696
 697                 if (--maxscan < 0)
 698                         break;
 699
 700                 opg = cfs_list_entry(cli->cl_lru_list.next, struct osc_page,
 701                                      ops_lru);
 702                 page = cl_page_top(opg->ops_cl.cpl_page);
 703                 if (page->cp_state == CPS_FREEING ||
 704                     cfs_atomic_read(&page->cp_ref) > 0) {
 705                         cfs_list_move_tail(&opg->ops_lru, &cli->cl_lru_list);
 706                         continue;
 707                 }
 708
 709                 LASSERT(page->cp_obj != NULL);
 710                 if (clobj != page->cp_obj) {
 711                         struct cl_object *tmp = page->cp_obj;
 712
 713                         cl_object_get(tmp);
 714                         client_obd_list_unlock(&cli->cl_lru_list_lock);
 715
 716                         if (clobj != NULL) {
 717                                 count -= discard_pagevec(env, io, pvec, index);
 718                                 index = 0;
 719
 720                                 cl_io_fini(env, io);
 721                                 cl_object_put(env, clobj);
 722                                 clobj = NULL;
 723                         }
 724
 725                         clobj = tmp;
 726                         io->ci_obj = clobj;
 727                         rc = cl_io_init(env, io, CIT_MISC, clobj);
 728                         if (rc != 0)
 729                                 break;
 730
 731                         ++maxscan;
 732                         client_obd_list_lock(&cli->cl_lru_list_lock);
 733                         continue;
 734                 }
 735
 736                 /* move this page to the end of list as it will be discarded
 737                  * soon. The page will be finally removed from LRU list in
 738                  * osc_page_delete().  */
 739                 cfs_list_move_tail(&opg->ops_lru, &cli->cl_lru_list);
 740
 741                 /* it's okay to grab a refcount here w/o holding lock because
 742                  * it has to grab cl_lru_list_lock to delete the page. */
 743                 cl_page_get(page);
 744                 pvec[index++] = page;
 745                 if (++count >= target)
 746                         break;
 747
 748                 if (unlikely(index == OTI_PVEC_SIZE)) {
 749                         client_obd_list_unlock(&cli->cl_lru_list_lock);
 750                         count -= discard_pagevec(env, io, pvec, index);
 751                         index = 0;
 752
 753                         client_obd_list_lock(&cli->cl_lru_list_lock);
 754                 }
 755         }
 756         client_obd_list_unlock(&cli->cl_lru_list_lock);
 757
 758         if (clobj != NULL) {
 759                 count -= discard_pagevec(env, io, pvec, index);
 760
 761                 cl_io_fini(env, io);
 762                 cl_object_put(env, clobj);
 763         }
 764         cl_env_nested_put(&nest, env);
 765
 766         cfs_atomic_dec(&cli->cl_lru_shrinkers);
 767         RETURN(count > 0 ? count : rc);
 768 }
 769
 770 static void osc_lru_add(struct client_obd *cli, struct osc_page *opg)
 771 {
 772         bool wakeup = false;
 773
 774         if (!opg->ops_in_lru)
 775                 return;
 776
 777         cfs_atomic_dec(&cli->cl_lru_busy);
 778         client_obd_list_lock(&cli->cl_lru_list_lock);
 779         if (cfs_list_empty(&opg->ops_lru)) {
 780                 cfs_list_move_tail(&opg->ops_lru, &cli->cl_lru_list);
 781                 cfs_atomic_inc_return(&cli->cl_lru_in_list);
 782                 wakeup = cfs_atomic_read(&osc_lru_waiters) > 0;
 783         }
 784         client_obd_list_unlock(&cli->cl_lru_list_lock);
 785
 786         if (wakeup)
 787                 cfs_waitq_broadcast(&osc_lru_waitq);
 788 }
 789
 790 /* delete page from LRUlist. The page can be deleted from LRUlist for two
 791  * reasons: redirtied or deleted from page cache. */
 792 static void osc_lru_del(struct client_obd *cli, struct osc_page *opg, bool del)
 793 {
 794         if (opg->ops_in_lru) {
 795                 client_obd_list_lock(&cli->cl_lru_list_lock);
 796                 if (!cfs_list_empty(&opg->ops_lru)) {
 797                         LASSERT(cfs_atomic_read(&cli->cl_lru_in_list) > 0);
 798                         cfs_list_del_init(&opg->ops_lru);
 799                         cfs_atomic_dec(&cli->cl_lru_in_list);
 800                         if (!del)
 801                                 cfs_atomic_inc(&cli->cl_lru_busy);
 802                 } else if (del) {
 803                         LASSERT(cfs_atomic_read(&cli->cl_lru_busy) > 0);
 804                         cfs_atomic_dec(&cli->cl_lru_busy);
 805                 }
 806                 client_obd_list_unlock(&cli->cl_lru_list_lock);
 807                 if (del) {
 808                         cfs_atomic_inc(cli->cl_lru_left);
 809                         /* this is a great place to release more LRU pages if
 810                          * this osc occupies too many LRU pages and kernel is
 811                          * stealing one of them.
 812                          * cl_lru_shrinkers is to avoid recursive call in case
 813                          * we're already in the context of osc_lru_shrink(). */
 814                         if (cfs_atomic_read(&cli->cl_lru_shrinkers) == 0)
 815                                 osc_lru_shrink(cli, osc_cache_too_much(cli));
 816                         cfs_waitq_signal(&osc_lru_waitq);
 817                 }
 818         } else {
 819                 LASSERT(cfs_list_empty(&opg->ops_lru));
 820         }
 821 }
 822
 823 static int osc_lru_reclaim(struct client_obd *cli)
 824 {
 825         struct cl_client_cache *cache = cli->cl_cache;
 826         struct client_obd *victim;
 827         struct client_obd *tmp;
 828         int rc;
 829
 830         LASSERT(cache != NULL);
 831         LASSERT(!cfs_list_empty(&cache->ccc_lru));
 832
 833         rc = osc_lru_shrink(cli, lru_shrink_min);
 834         if (rc > 0) {
 835                 CDEBUG(D_CACHE, "%s: Free %d pages from own LRU: %p.\n",
 836                         cli->cl_import->imp_obd->obd_name, rc, cli);
 837                 return rc;
 838         }
 839
 840         CDEBUG(D_CACHE, "%s: cli %p no free slots, pages: %d, busy: %d.\n",
 841                 cli->cl_import->imp_obd->obd_name, cli,
 842                 cfs_atomic_read(&cli->cl_lru_in_list),
 843                 cfs_atomic_read(&cli->cl_lru_busy));
 844
 845         /* Reclaim LRU slots from other client_obd as it can't free enough
 846          * from its own. This should rarely happen. */
 847         spin_lock(&cache->ccc_lru_lock);
 848         cache->ccc_lru_shrinkers++;
 849         cfs_list_move_tail(&cli->cl_lru_osc, &cache->ccc_lru);
 850         cfs_list_for_each_entry_safe(victim, tmp, &cache->ccc_lru, cl_lru_osc) {
 851                 if (victim == cli)
 852                         break;
 853
 854                 CDEBUG(D_CACHE, "%s: cli %p LRU pages: %d, busy: %d.\n",
 855                         victim->cl_import->imp_obd->obd_name, victim,
 856                         cfs_atomic_read(&victim->cl_lru_in_list),
 857                         cfs_atomic_read(&victim->cl_lru_busy));
 858
 859                 cfs_list_move_tail(&victim->cl_lru_osc, &cache->ccc_lru);
 860                 if (cfs_atomic_read(&victim->cl_lru_in_list) > 0)
 861                         break;
 862         }
 863         spin_unlock(&cache->ccc_lru_lock);
 864         if (victim == cli) {
 865                 CDEBUG(D_CACHE, "%s: can't get any free LRU slots.\n",
 866                         cli->cl_import->imp_obd->obd_name);
 867                 return 0;
 868         }
 869
 870         rc = osc_lru_shrink(victim,
 871                             min(cfs_atomic_read(&victim->cl_lru_in_list) >> 1,
 872                                 lru_shrink_max));
 873
 874         CDEBUG(D_CACHE, "%s: Free %d pages from other cli: %p.\n",
 875                 cli->cl_import->imp_obd->obd_name, rc, victim);
 876
 877         return rc;
 878 }
 879
 880 static int osc_lru_reserve(const struct lu_env *env, struct osc_object *obj,
 881                            struct osc_page *opg)
 882 {
 883         struct l_wait_info lwi = LWI_INTR(LWI_ON_SIGNAL_NOOP, NULL);
 884         struct client_obd *cli = osc_cli(obj);
 885         int rc = 0;
 886         ENTRY;
 887
 888         if (cli->cl_cache == NULL) /* shall not be in LRU */
 889                 RETURN(0);
 890
 891         LASSERT(cfs_atomic_read(cli->cl_lru_left) >= 0);
 892         while (!cfs_atomic_add_unless(cli->cl_lru_left, -1, 0)) {
 893                 int gen;
 894
 895                 /* run out of LRU spaces, try to drop some by itself */
 896                 rc = osc_lru_reclaim(cli);
 897                 if (rc < 0)
 898                         break;
 899                 if (rc > 0)
 900                         continue;
 901
 902                 cfs_cond_resched();
 903
 904                 /* slowest case, all of caching pages are busy, notifying
 905                  * other OSCs that we're lack of LRU slots. */
 906                 cfs_atomic_inc(&osc_lru_waiters);
 907
 908                 gen = cfs_atomic_read(&cli->cl_lru_in_list);
 909                 rc = l_wait_event(osc_lru_waitq,
 910                                 cfs_atomic_read(cli->cl_lru_left) > 0 ||
 911                                 (cfs_atomic_read(&cli->cl_lru_in_list) > 0 &&
 912                                  gen != cfs_atomic_read(&cli->cl_lru_in_list)),
 913                                 &lwi);
 914
 915                 cfs_atomic_dec(&osc_lru_waiters);
 916                 if (rc < 0)
 917                         break;
 918         }
 919
 920         if (rc >= 0) {
 921                 cfs_atomic_inc(&cli->cl_lru_busy);
 922                 opg->ops_in_lru = 1;
 923                 rc = 0;
 924         }
 925
 926         RETURN(rc);
 927 }
 928
 929 /** @} osc */