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, 2014, Intel Corporation.
  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  *   Author: Jinshan Xiong <jinshan.xiong@intel.com>
  40  */
  41
  42 #define DEBUG_SUBSYSTEM S_OSC
  43
  44 #include "osc_cl_internal.h"
  45
  46 static void osc_lru_del(struct client_obd *cli, struct osc_page *opg);
  47 static void osc_lru_use(struct client_obd *cli, struct osc_page *opg);
  48 static int osc_lru_reserve(const struct lu_env *env, struct osc_object *obj,
  49                            struct osc_page *opg);
  50
  51 /** \addtogroup osc
  52  *  @{
  53  */
  54
  55 /*
  56  * Comment out osc_page_protected because it may sleep inside the
  57  * the client_obd_list_lock.
  58  * client_obd_list_lock -> osc_ap_completion -> osc_completion ->
  59  *   -> osc_page_protected -> osc_page_is_dlocked -> osc_match_base
  60  *   -> ldlm_lock_match -> sptlrpc_import_check_ctx -> sleep.
  61  */
  62 #if 0
  63 static int osc_page_is_dlocked(const struct lu_env *env,
  64                                const struct osc_page *opg,
  65                                enum cl_lock_mode mode, int pending, int unref)
  66 {
  67         struct cl_page         *page;
  68         struct osc_object      *obj;
  69         struct osc_thread_info *info;
  70         struct ldlm_res_id     *resname;
  71         struct lustre_handle   *lockh;
  72         ldlm_policy_data_t     *policy;
  73         ldlm_mode_t             dlmmode;
  74         __u64                   flags;
  75
  76         might_sleep();
  77
  78         info = osc_env_info(env);
  79         resname = &info->oti_resname;
  80         policy = &info->oti_policy;
  81         lockh = &info->oti_handle;
  82         page = opg->ops_cl.cpl_page;
  83         obj = cl2osc(opg->ops_cl.cpl_obj);
  84
  85         flags = LDLM_FL_TEST_LOCK | LDLM_FL_BLOCK_GRANTED;
  86         if (pending)
  87                 flags |= LDLM_FL_CBPENDING;
  88
  89         dlmmode = osc_cl_lock2ldlm(mode) | LCK_PW;
  90         osc_lock_build_res(env, obj, resname);
  91         osc_index2policy(policy, page->cp_obj, osc_index(opg), osc_index(opg));
  92         return osc_match_base(osc_export(obj), resname, LDLM_EXTENT, policy,
  93                               dlmmode, &flags, NULL, lockh, unref);
  94 }
  95
  96 /**
  97  * Checks an invariant that a page in the cache is covered by a lock, as
  98  * needed.
  99  */
 100 static int osc_page_protected(const struct lu_env *env,
 101                               const struct osc_page *opg,
 102                               enum cl_lock_mode mode, int unref)
 103 {
 104         struct cl_object_header *hdr;
 105         struct cl_lock          *scan;
 106         struct cl_page          *page;
 107         struct cl_lock_descr    *descr;
 108         int result;
 109
 110         LINVRNT(!opg->ops_temp);
 111
 112         page = opg->ops_cl.cpl_page;
 113         if (page->cp_owner != NULL &&
 114             cl_io_top(page->cp_owner)->ci_lockreq == CILR_NEVER)
 115                 /*
 116                  * If IO is done without locks (liblustre, or lloop), lock is
 117                  * not required.
 118                  */
 119                 result = 1;
 120         else
 121                 /* otherwise check for a DLM lock */
 122         result = osc_page_is_dlocked(env, opg, mode, 1, unref);
 123         if (result == 0) {
 124                 /* maybe this page is a part of a lockless io? */
 125                 hdr = cl_object_header(opg->ops_cl.cpl_obj);
 126                 descr = &osc_env_info(env)->oti_descr;
 127                 descr->cld_mode = mode;
 128                 descr->cld_start = osc_index(opg);
 129                 descr->cld_end   = osc_index(opg);
 130                 spin_lock(&hdr->coh_lock_guard);
 131                 list_for_each_entry(scan, &hdr->coh_locks, cll_linkage) {
 132                         /*
 133                          * Lock-less sub-lock has to be either in HELD state
 134                          * (when io is actively going on), or in CACHED state,
 135                          * when top-lock is being unlocked:
 136                          * cl_io_unlock()->cl_unuse()->...->lov_lock_unuse().
 137                          */
 138                         if ((scan->cll_state == CLS_HELD ||
 139                              scan->cll_state == CLS_CACHED) &&
 140                             cl_lock_ext_match(&scan->cll_descr, descr)) {
 141                                 struct osc_lock *olck;
 142
 143                                 olck = osc_lock_at(scan);
 144                                 result = osc_lock_is_lockless(olck);
 145                                 break;
 146                         }
 147                 }
 148                 spin_unlock(&hdr->coh_lock_guard);
 149         }
 150         return result;
 151 }
 152 #else
 153 static int osc_page_protected(const struct lu_env *env,
 154                               const struct osc_page *opg,
 155                               enum cl_lock_mode mode, int unref)
 156 {
 157         return 1;
 158 }
 159 #endif
 160
 161 /*****************************************************************************
 162  *
 163  * Page operations.
 164  *
 165  */
 166 static void osc_page_transfer_get(struct osc_page *opg, const char *label)
 167 {
 168         struct cl_page *page = opg->ops_cl.cpl_page;
 169
 170         LASSERT(!opg->ops_transfer_pinned);
 171         cl_page_get(page);
 172         lu_ref_add_atomic(&page->cp_reference, label, page);
 173         opg->ops_transfer_pinned = 1;
 174 }
 175
 176 static void osc_page_transfer_put(const struct lu_env *env,
 177                                   struct osc_page *opg)
 178 {
 179         struct cl_page *page = opg->ops_cl.cpl_page;
 180
 181         if (opg->ops_transfer_pinned) {
 182                 opg->ops_transfer_pinned = 0;
 183                 lu_ref_del(&page->cp_reference, "transfer", page);
 184                 cl_page_put(env, page);
 185         }
 186 }
 187
 188 /**
 189  * This is called once for every page when it is submitted for a transfer
 190  * either opportunistic (osc_page_cache_add()), or immediate
 191  * (osc_page_submit()).
 192  */
 193 static void osc_page_transfer_add(const struct lu_env *env,
 194                                   struct osc_page *opg, enum cl_req_type crt)
 195 {
 196         struct osc_object *obj = cl2osc(opg->ops_cl.cpl_obj);
 197
 198         /* ops_lru and ops_inflight share the same field, so take it from LRU
 199          * first and then use it as inflight. */
 200         osc_lru_use(osc_cli(obj), opg);
 201
 202         spin_lock(&obj->oo_seatbelt);
 203         list_add(&opg->ops_inflight, &obj->oo_inflight[crt]);
 204         opg->ops_submitter = current;
 205         spin_unlock(&obj->oo_seatbelt);
 206 }
 207
 208 int osc_page_cache_add(const struct lu_env *env,
 209                         const struct cl_page_slice *slice, struct cl_io *io)
 210 {
 211         struct osc_page *opg = cl2osc_page(slice);
 212         int result;
 213         ENTRY;
 214
 215         LINVRNT(osc_page_protected(env, opg, CLM_WRITE, 0));
 216
 217         osc_page_transfer_get(opg, "transfer\0cache");
 218         result = osc_queue_async_io(env, io, opg);
 219         if (result != 0)
 220                 osc_page_transfer_put(env, opg);
 221         else
 222                 osc_page_transfer_add(env, opg, CRT_WRITE);
 223
 224         RETURN(result);
 225 }
 226
 227 void osc_index2policy(ldlm_policy_data_t *policy, const struct cl_object *obj,
 228                       pgoff_t start, pgoff_t end)
 229 {
 230         memset(policy, 0, sizeof *policy);
 231         policy->l_extent.start = cl_offset(obj, start);
 232         policy->l_extent.end   = cl_offset(obj, end + 1) - 1;
 233 }
 234
 235 static const char *osc_list(struct list_head *head)
 236 {
 237         return list_empty(head) ? "-" : "+";
 238 }
 239
 240 static inline cfs_time_t osc_submit_duration(struct osc_page *opg)
 241 {
 242         if (opg->ops_submit_time == 0)
 243                 return 0;
 244
 245         return (cfs_time_current() - opg->ops_submit_time);
 246 }
 247
 248 static int osc_page_print(const struct lu_env *env,
 249                           const struct cl_page_slice *slice,
 250                           void *cookie, lu_printer_t printer)
 251 {
 252         struct osc_page       *opg = cl2osc_page(slice);
 253         struct osc_async_page *oap = &opg->ops_oap;
 254         struct osc_object     *obj = cl2osc(slice->cpl_obj);
 255         struct client_obd     *cli = &osc_export(obj)->exp_obd->u.cli;
 256
 257         return (*printer)(env, cookie, LUSTRE_OSC_NAME"-page@%p %lu: "
 258                           "1< %#x %d %u %s %s > "
 259                           "2< "LPU64" %u %u %#x %#x | %p %p %p > "
 260                           "3< %s %p %d %lu %d > "
 261                           "4< %d %d %d %lu %s | %s %s %s %s > "
 262                           "5< %s %s %s %s | %d %s | %d %s %s>\n",
 263                           opg, osc_index(opg),
 264                           /* 1 */
 265                           oap->oap_magic, oap->oap_cmd,
 266                           oap->oap_interrupted,
 267                           osc_list(&oap->oap_pending_item),
 268                           osc_list(&oap->oap_rpc_item),
 269                           /* 2 */
 270                           oap->oap_obj_off, oap->oap_page_off, oap->oap_count,
 271                           oap->oap_async_flags, oap->oap_brw_flags,
 272                           oap->oap_request, oap->oap_cli, obj,
 273                           /* 3 */
 274                           osc_list(&opg->ops_inflight),
 275                           opg->ops_submitter, opg->ops_transfer_pinned,
 276                           osc_submit_duration(opg), opg->ops_srvlock,
 277                           /* 4 */
 278                           cli->cl_r_in_flight, cli->cl_w_in_flight,
 279                           cli->cl_max_rpcs_in_flight,
 280                           cli->cl_avail_grant,
 281                           osc_list(&cli->cl_cache_waiters),
 282                           osc_list(&cli->cl_loi_ready_list),
 283                           osc_list(&cli->cl_loi_hp_ready_list),
 284                           osc_list(&cli->cl_loi_write_list),
 285                           osc_list(&cli->cl_loi_read_list),
 286                           /* 5 */
 287                           osc_list(&obj->oo_ready_item),
 288                           osc_list(&obj->oo_hp_ready_item),
 289                           osc_list(&obj->oo_write_item),
 290                           osc_list(&obj->oo_read_item),
 291                           atomic_read(&obj->oo_nr_reads),
 292                           osc_list(&obj->oo_reading_exts),
 293                           atomic_read(&obj->oo_nr_writes),
 294                           osc_list(&obj->oo_hp_exts),
 295                           osc_list(&obj->oo_urgent_exts));
 296 }
 297
 298 static void osc_page_delete(const struct lu_env *env,
 299                             const struct cl_page_slice *slice)
 300 {
 301         struct osc_page   *opg = cl2osc_page(slice);
 302         struct osc_object *obj = cl2osc(opg->ops_cl.cpl_obj);
 303         int rc;
 304
 305         LINVRNT(opg->ops_temp || osc_page_protected(env, opg, CLM_READ, 1));
 306
 307         ENTRY;
 308         CDEBUG(D_TRACE, "%p\n", opg);
 309         osc_page_transfer_put(env, opg);
 310         rc = osc_teardown_async_page(env, obj, opg);
 311         if (rc) {
 312                 CL_PAGE_DEBUG(D_ERROR, env, slice->cpl_page,
 313                               "Trying to teardown failed: %d\n", rc);
 314                 LASSERT(0);
 315         }
 316
 317         spin_lock(&obj->oo_seatbelt);
 318         if (opg->ops_submitter != NULL) {
 319                 LASSERT(!list_empty(&opg->ops_inflight));
 320                 list_del_init(&opg->ops_inflight);
 321                 opg->ops_submitter = NULL;
 322         }
 323         spin_unlock(&obj->oo_seatbelt);
 324
 325         osc_lru_del(osc_cli(obj), opg);
 326
 327         if (slice->cpl_page->cp_type == CPT_CACHEABLE) {
 328                 void *value;
 329
 330                 spin_lock(&obj->oo_tree_lock);
 331                 value = radix_tree_delete(&obj->oo_tree, osc_index(opg));
 332                 if (value != NULL)
 333                         --obj->oo_npages;
 334                 spin_unlock(&obj->oo_tree_lock);
 335
 336                 LASSERT(ergo(value != NULL, value == opg));
 337         }
 338
 339         EXIT;
 340 }
 341
 342 static void osc_page_clip(const struct lu_env *env,
 343                           const struct cl_page_slice *slice,
 344                           int from, int to)
 345 {
 346         struct osc_page       *opg = cl2osc_page(slice);
 347         struct osc_async_page *oap = &opg->ops_oap;
 348
 349         LINVRNT(osc_page_protected(env, opg, CLM_READ, 0));
 350
 351         opg->ops_from = from;
 352         opg->ops_to   = to;
 353         spin_lock(&oap->oap_lock);
 354         oap->oap_async_flags |= ASYNC_COUNT_STABLE;
 355         spin_unlock(&oap->oap_lock);
 356 }
 357
 358 static int osc_page_cancel(const struct lu_env *env,
 359                            const struct cl_page_slice *slice)
 360 {
 361         struct osc_page *opg = cl2osc_page(slice);
 362         int rc = 0;
 363
 364         LINVRNT(osc_page_protected(env, opg, CLM_READ, 0));
 365
 366         /* Check if the transferring against this page
 367          * is completed, or not even queued. */
 368         if (opg->ops_transfer_pinned)
 369                 /* FIXME: may not be interrupted.. */
 370                 rc = osc_cancel_async_page(env, opg);
 371         LASSERT(ergo(rc == 0, opg->ops_transfer_pinned == 0));
 372         return rc;
 373 }
 374
 375 static int osc_page_flush(const struct lu_env *env,
 376                           const struct cl_page_slice *slice,
 377                           struct cl_io *io)
 378 {
 379         struct osc_page *opg = cl2osc_page(slice);
 380         int rc = 0;
 381         ENTRY;
 382         rc = osc_flush_async_page(env, io, opg);
 383         RETURN(rc);
 384 }
 385
 386 static const struct cl_page_operations osc_page_ops = {
 387         .cpo_print         = osc_page_print,
 388         .cpo_delete        = osc_page_delete,
 389         .cpo_clip           = osc_page_clip,
 390         .cpo_cancel         = osc_page_cancel,
 391         .cpo_flush          = osc_page_flush
 392 };
 393
 394 int osc_page_init(const struct lu_env *env, struct cl_object *obj,
 395                   struct cl_page *page, pgoff_t index)
 396 {
 397         struct osc_object *osc = cl2osc(obj);
 398         struct osc_page   *opg = cl_object_page_slice(obj, page);
 399         int result;
 400
 401         opg->ops_from = 0;
 402         opg->ops_to   = PAGE_CACHE_SIZE;
 403
 404         result = osc_prep_async_page(osc, opg, page->cp_vmpage,
 405                                      cl_offset(obj, index));
 406         if (result == 0) {
 407                 struct osc_io *oio = osc_env_io(env);
 408                 opg->ops_srvlock = osc_io_srvlock(oio);
 409                 cl_page_slice_add(page, &opg->ops_cl, obj, index,
 410                                   &osc_page_ops);
 411         }
 412         /*
 413          * Cannot assert osc_page_protected() here as read-ahead
 414          * creates temporary pages outside of a lock.
 415          */
 416 #ifdef CONFIG_LUSTRE_DEBUG_EXPENSIVE_CHECK
 417         opg->ops_temp = !osc_page_protected(env, opg, CLM_READ, 1);
 418 #endif
 419         /* ops_inflight and ops_lru are the same field, but it doesn't
 420          * hurt to initialize it twice :-) */
 421         INIT_LIST_HEAD(&opg->ops_inflight);
 422         INIT_LIST_HEAD(&opg->ops_lru);
 423
 424         /* reserve an LRU space for this page */
 425         if (page->cp_type == CPT_CACHEABLE && result == 0) {
 426                 result = osc_lru_reserve(env, osc, opg);
 427                 if (result == 0) {
 428                         spin_lock(&osc->oo_tree_lock);
 429                         result = radix_tree_insert(&osc->oo_tree, index, opg);
 430                         if (result == 0)
 431                                 ++osc->oo_npages;
 432                         spin_unlock(&osc->oo_tree_lock);
 433                         LASSERT(result == 0);
 434                 }
 435         }
 436
 437         return result;
 438 }
 439
 440 /**
 441  * Helper function called by osc_io_submit() for every page in an immediate
 442  * transfer (i.e., transferred synchronously).
 443  */
 444 void osc_page_submit(const struct lu_env *env, struct osc_page *opg,
 445                      enum cl_req_type crt, int brw_flags)
 446 {
 447         struct osc_async_page *oap = &opg->ops_oap;
 448         struct osc_object     *obj = oap->oap_obj;
 449
 450         LINVRNT(osc_page_protected(env, opg,
 451                                    crt == CRT_WRITE ? CLM_WRITE : CLM_READ, 1));
 452
 453         LASSERTF(oap->oap_magic == OAP_MAGIC, "Bad oap magic: oap %p, "
 454                  "magic 0x%x\n", oap, oap->oap_magic);
 455         LASSERT(oap->oap_async_flags & ASYNC_READY);
 456         LASSERT(oap->oap_async_flags & ASYNC_COUNT_STABLE);
 457
 458         oap->oap_cmd       = crt == CRT_WRITE ? OBD_BRW_WRITE : OBD_BRW_READ;
 459         oap->oap_page_off  = opg->ops_from;
 460         oap->oap_count     = opg->ops_to - opg->ops_from;
 461         oap->oap_brw_flags = OBD_BRW_SYNC | brw_flags;
 462
 463         if (!client_is_remote(osc_export(obj)) &&
 464                         cfs_capable(CFS_CAP_SYS_RESOURCE)) {
 465                 oap->oap_brw_flags |= OBD_BRW_NOQUOTA;
 466                 oap->oap_cmd |= OBD_BRW_NOQUOTA;
 467         }
 468
 469         opg->ops_submit_time = cfs_time_current();
 470         osc_page_transfer_get(opg, "transfer\0imm");
 471         osc_page_transfer_add(env, opg, crt);
 472 }
 473
 474 /* --------------- LRU page management ------------------ */
 475
 476 /* OSC is a natural place to manage LRU pages as applications are specialized
 477  * to write OSC by OSC. Ideally, if one OSC is used more frequently it should
 478  * occupy more LRU slots. On the other hand, we should avoid using up all LRU
 479  * slots (client_obd::cl_lru_left) otherwise process has to be put into sleep
 480  * for free LRU slots - this will be very bad so the algorithm requires each
 481  * OSC to free slots voluntarily to maintain a reasonable number of free slots
 482  * at any time.
 483  */
 484
 485 static CFS_DECL_WAITQ(osc_lru_waitq);
 486 /* LRU pages are freed in batch mode. OSC should at least free this
 487  * number of pages to avoid running out of LRU budget, and.. */
 488 static const int lru_shrink_min = 2 << (20 - PAGE_CACHE_SHIFT); /* 2M */
 489 /* free this number at most otherwise it will take too long time to finsih. */
 490 static const int lru_shrink_max = 8 << (20 - PAGE_CACHE_SHIFT); /* 8M */
 491
 492 /* Check if we can free LRU slots from this OSC. If there exists LRU waiters,
 493  * we should free slots aggressively. In this way, slots are freed in a steady
 494  * step to maintain fairness among OSCs.
 495  *
 496  * Return how many LRU pages should be freed. */
 497 static int osc_cache_too_much(struct client_obd *cli)
 498 {
 499         struct cl_client_cache *cache = cli->cl_cache;
 500         long pages = atomic_long_read(&cli->cl_lru_in_list);
 501         unsigned long budget;
 502
 503         LASSERT(cache != NULL);
 504         budget = cache->ccc_lru_max / (atomic_read(&cache->ccc_users) - 2);
 505
 506         /* if it's going to run out LRU slots, we should free some, but not
 507          * too much to maintain faireness among OSCs. */
 508         if (atomic_long_read(cli->cl_lru_left) < cache->ccc_lru_max >> 4) {
 509                 if (pages >= budget)
 510                         return lru_shrink_max;
 511                 else if (pages >= budget / 2)
 512                         return lru_shrink_min;
 513         } else if (pages >= budget * 2)
 514                 return lru_shrink_min;
 515         return 0;
 516 }
 517
 518 int lru_queue_work(const struct lu_env *env, void *data)
 519 {
 520         struct client_obd *cli = data;
 521
 522         CDEBUG(D_CACHE, "Run LRU work for client obd %p.\n", cli);
 523
 524         if (osc_cache_too_much(cli))
 525                 osc_lru_shrink(env, cli, lru_shrink_max, true);
 526
 527         RETURN(0);
 528 }
 529
 530 void osc_lru_add_batch(struct client_obd *cli, struct list_head *plist)
 531 {
 532         struct list_head lru = LIST_HEAD_INIT(lru);
 533         struct osc_async_page *oap;
 534         long npages = 0;
 535
 536         list_for_each_entry(oap, plist, oap_pending_item) {
 537                 struct osc_page *opg = oap2osc_page(oap);
 538
 539                 if (!opg->ops_in_lru)
 540                         continue;
 541
 542                 ++npages;
 543                 LASSERT(list_empty(&opg->ops_lru));
 544                 list_add(&opg->ops_lru, &lru);
 545         }
 546
 547         if (npages > 0) {
 548                 spin_lock(&cli->cl_lru_list_lock);
 549                 list_splice_tail(&lru, &cli->cl_lru_list);
 550                 atomic_long_sub(npages, &cli->cl_lru_busy);
 551                 atomic_long_add(npages, &cli->cl_lru_in_list);
 552                 spin_unlock(&cli->cl_lru_list_lock);
 553
 554                 /* XXX: May set force to be true for better performance */
 555                 if (osc_cache_too_much(cli))
 556                         (void)ptlrpcd_queue_work(cli->cl_lru_work);
 557         }
 558 }
 559
 560 static void __osc_lru_del(struct client_obd *cli, struct osc_page *opg)
 561 {
 562         LASSERT(atomic_long_read(&cli->cl_lru_in_list) > 0);
 563         list_del_init(&opg->ops_lru);
 564         atomic_long_dec(&cli->cl_lru_in_list);
 565 }
 566
 567 /**
 568  * Page is being destroyed. The page may be not in LRU list, if the transfer
 569  * has never finished(error occurred).
 570  */
 571 static void osc_lru_del(struct client_obd *cli, struct osc_page *opg)
 572 {
 573         if (opg->ops_in_lru) {
 574                 spin_lock(&cli->cl_lru_list_lock);
 575                 if (!list_empty(&opg->ops_lru)) {
 576                         __osc_lru_del(cli, opg);
 577                 } else {
 578                         LASSERT(atomic_long_read(&cli->cl_lru_busy) > 0);
 579                         atomic_long_dec(&cli->cl_lru_busy);
 580                 }
 581                 spin_unlock(&cli->cl_lru_list_lock);
 582
 583                 atomic_long_inc(cli->cl_lru_left);
 584                 /* this is a great place to release more LRU pages if
 585                  * this osc occupies too many LRU pages and kernel is
 586                  * stealing one of them. */
 587                 if (!memory_pressure_get())
 588                         (void)ptlrpcd_queue_work(cli->cl_lru_work);
 589                 wake_up(&osc_lru_waitq);
 590         } else {
 591                 LASSERT(list_empty(&opg->ops_lru));
 592         }
 593 }
 594
 595 /**
 596  * Delete page from LRUlist for redirty.
 597  */
 598 static void osc_lru_use(struct client_obd *cli, struct osc_page *opg)
 599 {
 600         /* If page is being transfered for the first time,
 601          * ops_lru should be empty */
 602         if (opg->ops_in_lru && !list_empty(&opg->ops_lru)) {
 603                 spin_lock(&cli->cl_lru_list_lock);
 604                 __osc_lru_del(cli, opg);
 605                 spin_unlock(&cli->cl_lru_list_lock);
 606                 atomic_long_inc(&cli->cl_lru_busy);
 607         }
 608 }
 609
 610 static void discard_pagevec(const struct lu_env *env, struct cl_io *io,
 611                                 struct cl_page **pvec, int max_index)
 612 {
 613         int i;
 614
 615         for (i = 0; i < max_index; i++) {
 616                 struct cl_page *page = pvec[i];
 617
 618                 LASSERT(cl_page_is_owned(page, io));
 619                 cl_page_discard(env, io, page);
 620                 cl_page_disown(env, io, page);
 621                 cl_page_put(env, page);
 622
 623                 pvec[i] = NULL;
 624         }
 625 }
 626
 627 /**
 628  * Check if a cl_page can be released, i.e, it's not being used.
 629  *
 630  * If unstable account is turned on, bulk transfer may hold one refcount
 631  * for recovery so we need to check vmpage refcount as well; otherwise,
 632  * even we can destroy cl_page but the corresponding vmpage can't be reused.
 633  */
 634 static inline bool lru_page_busy(struct client_obd *cli, struct cl_page *page)
 635 {
 636         if (cl_page_in_use_noref(page))
 637                 return true;
 638
 639         if (cli->cl_cache->ccc_unstable_check) {
 640                 struct page *vmpage = cl_page_vmpage(page);
 641
 642                 /* vmpage have two known users: cl_page and VM page cache */
 643                 if (page_count(vmpage) - page_mapcount(vmpage) > 2)
 644                         return true;
 645         }
 646         return false;
 647 }
 648
 649 /**
 650  * Drop @target of pages from LRU at most.
 651  */
 652 long osc_lru_shrink(const struct lu_env *env, struct client_obd *cli,
 653                    long target, bool force)
 654 {
 655         struct cl_io *io;
 656         struct cl_object *clobj = NULL;
 657         struct cl_page **pvec;
 658         struct osc_page *opg;
 659         long count = 0;
 660         int maxscan = 0;
 661         int index = 0;
 662         int rc = 0;
 663         ENTRY;
 664
 665         LASSERT(atomic_long_read(&cli->cl_lru_in_list) >= 0);
 666         if (atomic_long_read(&cli->cl_lru_in_list) == 0 || target <= 0)
 667                 RETURN(0);
 668
 669         if (!force) {
 670                 if (atomic_read(&cli->cl_lru_shrinkers) > 0)
 671                         RETURN(-EBUSY);
 672
 673                 if (atomic_inc_return(&cli->cl_lru_shrinkers) > 1) {
 674                         atomic_dec(&cli->cl_lru_shrinkers);
 675                         RETURN(-EBUSY);
 676                 }
 677         } else {
 678                 atomic_inc(&cli->cl_lru_shrinkers);
 679         }
 680
 681         pvec = (struct cl_page **)osc_env_info(env)->oti_pvec;
 682         io = &osc_env_info(env)->oti_io;
 683
 684         spin_lock(&cli->cl_lru_list_lock);
 685         maxscan = min(target << 1, atomic_long_read(&cli->cl_lru_in_list));
 686         while (!list_empty(&cli->cl_lru_list)) {
 687                 struct cl_page *page;
 688                 bool will_free = false;
 689
 690                 if (--maxscan < 0)
 691                         break;
 692
 693                 opg = list_entry(cli->cl_lru_list.next, struct osc_page,
 694                                  ops_lru);
 695                 page = opg->ops_cl.cpl_page;
 696                 if (lru_page_busy(cli, page)) {
 697                         list_move_tail(&opg->ops_lru, &cli->cl_lru_list);
 698                         continue;
 699                 }
 700
 701                 LASSERT(page->cp_obj != NULL);
 702                 if (clobj != page->cp_obj) {
 703                         struct cl_object *tmp = page->cp_obj;
 704
 705                         cl_object_get(tmp);
 706                         spin_unlock(&cli->cl_lru_list_lock);
 707
 708                         if (clobj != NULL) {
 709                                 discard_pagevec(env, io, pvec, index);
 710                                 index = 0;
 711
 712                                 cl_io_fini(env, io);
 713                                 cl_object_put(env, clobj);
 714                                 clobj = NULL;
 715                         }
 716
 717                         clobj = tmp;
 718                         io->ci_obj = clobj;
 719                         io->ci_ignore_layout = 1;
 720                         rc = cl_io_init(env, io, CIT_MISC, clobj);
 721
 722                         spin_lock(&cli->cl_lru_list_lock);
 723
 724                         if (rc != 0)
 725                                 break;
 726
 727                         ++maxscan;
 728                         continue;
 729                 }
 730
 731                 if (cl_page_own_try(env, io, page) == 0) {
 732                         if (!lru_page_busy(cli, page)) {
 733                                 /* remove it from lru list earlier to avoid
 734                                  * lock contention */
 735                                 __osc_lru_del(cli, opg);
 736                                 opg->ops_in_lru = 0; /* will be discarded */
 737
 738                                 cl_page_get(page);
 739                                 will_free = true;
 740                         } else {
 741                                 cl_page_disown(env, io, page);
 742                         }
 743                 }
 744
 745                 if (!will_free) {
 746                         list_move_tail(&opg->ops_lru, &cli->cl_lru_list);
 747                         continue;
 748                 }
 749
 750                 /* Don't discard and free the page with cl_lru_list held */
 751                 pvec[index++] = page;
 752                 if (unlikely(index == OTI_PVEC_SIZE)) {
 753                         spin_unlock(&cli->cl_lru_list_lock);
 754                         discard_pagevec(env, io, pvec, index);
 755                         index = 0;
 756
 757                         spin_lock(&cli->cl_lru_list_lock);
 758                 }
 759
 760                 if (++count >= target)
 761                         break;
 762         }
 763         spin_unlock(&cli->cl_lru_list_lock);
 764
 765         if (clobj != NULL) {
 766                 discard_pagevec(env, io, pvec, index);
 767
 768                 cl_io_fini(env, io);
 769                 cl_object_put(env, clobj);
 770         }
 771
 772         atomic_dec(&cli->cl_lru_shrinkers);
 773         if (count > 0) {
 774                 atomic_long_add(count, cli->cl_lru_left);
 775                 wake_up_all(&osc_lru_waitq);
 776         }
 777         RETURN(count > 0 ? count : rc);
 778 }
 779
 780 long osc_lru_reclaim(struct client_obd *cli)
 781 {
 782         struct cl_env_nest nest;
 783         struct lu_env *env;
 784         struct cl_client_cache *cache = cli->cl_cache;
 785         long rc = 0;
 786         int max_scans;
 787         ENTRY;
 788
 789         LASSERT(cache != NULL);
 790         LASSERT(!list_empty(&cache->ccc_lru));
 791
 792         env = cl_env_nested_get(&nest);
 793         if (IS_ERR(env))
 794                 RETURN(rc);
 795
 796         rc = osc_lru_shrink(env, cli, osc_cache_too_much(cli), false);
 797         if (rc != 0) {
 798                 if (rc == -EBUSY)
 799                         rc = 0;
 800
 801                 CDEBUG(D_CACHE, "%s: Free %ld pages from own LRU: %p.\n",
 802                         cli->cl_import->imp_obd->obd_name, rc, cli);
 803                 GOTO(out, rc);
 804         }
 805
 806         CDEBUG(D_CACHE, "%s: cli %p no free slots, pages: %ld, busy: %ld.\n",
 807                 cli->cl_import->imp_obd->obd_name, cli,
 808                 atomic_long_read(&cli->cl_lru_in_list),
 809                 atomic_long_read(&cli->cl_lru_busy));
 810
 811         /* Reclaim LRU slots from other client_obd as it can't free enough
 812          * from its own. This should rarely happen. */
 813         spin_lock(&cache->ccc_lru_lock);
 814         cache->ccc_lru_shrinkers++;
 815         list_move_tail(&cli->cl_lru_osc, &cache->ccc_lru);
 816
 817         max_scans = atomic_read(&cache->ccc_users) - 2;
 818         while (--max_scans > 0 && !list_empty(&cache->ccc_lru)) {
 819                 cli = list_entry(cache->ccc_lru.next, struct client_obd,
 820                                  cl_lru_osc);
 821
 822                 CDEBUG(D_CACHE, "%s: cli %p LRU pages: %ld, busy: %ld.\n",
 823                         cli->cl_import->imp_obd->obd_name, cli,
 824                         atomic_long_read(&cli->cl_lru_in_list),
 825                         atomic_long_read(&cli->cl_lru_busy));
 826
 827                 list_move_tail(&cli->cl_lru_osc, &cache->ccc_lru);
 828                 if (osc_cache_too_much(cli) > 0) {
 829                         spin_unlock(&cache->ccc_lru_lock);
 830
 831                         rc = osc_lru_shrink(env, cli, osc_cache_too_much(cli),
 832                                             true);
 833                         spin_lock(&cache->ccc_lru_lock);
 834                         if (rc != 0)
 835                                 break;
 836                 }
 837         }
 838         spin_unlock(&cache->ccc_lru_lock);
 839
 840 out:
 841         cl_env_nested_put(&nest, env);
 842         CDEBUG(D_CACHE, "%s: cli %p freed %ld pages.\n",
 843                 cli->cl_import->imp_obd->obd_name, cli, rc);
 844         return rc;
 845 }
 846
 847 /**
 848  * osc_lru_reserve() is called to reserve an LRU slot for a cl_page.
 849  *
 850  * Usually the LRU slots are reserved in osc_io_iter_rw_init().
 851  * Only in the case that the LRU slots are in extreme shortage, it should
 852  * have reserved enough slots for an IO.
 853  */
 854 static int osc_lru_reserve(const struct lu_env *env, struct osc_object *obj,
 855                            struct osc_page *opg)
 856 {
 857         struct l_wait_info lwi = LWI_INTR(LWI_ON_SIGNAL_NOOP, NULL);
 858         struct osc_io *oio = osc_env_io(env);
 859         struct client_obd *cli = osc_cli(obj);
 860         int rc = 0;
 861         ENTRY;
 862
 863         if (cli->cl_cache == NULL) /* shall not be in LRU */
 864                 RETURN(0);
 865
 866         if (oio->oi_lru_reserved > 0) {
 867                 --oio->oi_lru_reserved;
 868                 goto out;
 869         }
 870
 871         LASSERT(atomic_long_read(cli->cl_lru_left) >= 0);
 872         while (!atomic_long_add_unless(cli->cl_lru_left, -1, 0)) {
 873
 874                 /* run out of LRU spaces, try to drop some by itself */
 875                 rc = osc_lru_reclaim(cli);
 876                 if (rc < 0)
 877                         break;
 878                 if (rc > 0)
 879                         continue;
 880
 881                 cond_resched();
 882                 rc = l_wait_event(osc_lru_waitq,
 883                                 atomic_long_read(cli->cl_lru_left) > 0,
 884                                 &lwi);
 885                 if (rc < 0)
 886                         break;
 887         }
 888
 889 out:
 890         if (rc >= 0) {
 891                 atomic_long_inc(&cli->cl_lru_busy);
 892                 opg->ops_in_lru = 1;
 893                 rc = 0;
 894         }
 895
 896         RETURN(rc);
 897 }
 898
 899 /**
 900  * Atomic operations are expensive. We accumulate the accounting for the
 901  * same page zone to get better performance.
 902  * In practice this can work pretty good because the pages in the same RPC
 903  * are likely from the same page zone.
 904  */
 905 static inline void unstable_page_accounting(struct ptlrpc_bulk_desc *desc,
 906                                             int factor)
 907 {
 908         obd_count page_count = desc->bd_iov_count;
 909         void *zone = NULL;
 910         int count = 0;
 911         int i;
 912
 913         for (i = 0; i < page_count; i++) {
 914                 void *pz = page_zone(desc->bd_iov[i].kiov_page);
 915
 916                 if (likely(pz == zone)) {
 917                         ++count;
 918                         continue;
 919                 }
 920
 921                 if (count > 0) {
 922                         mod_zone_page_state(zone, NR_UNSTABLE_NFS,
 923                                             factor * count);
 924                         count = 0;
 925                 }
 926                 zone = pz;
 927                 ++count;
 928         }
 929         if (count > 0)
 930                 mod_zone_page_state(zone, NR_UNSTABLE_NFS, factor * count);
 931 }
 932
 933 static inline void add_unstable_page_accounting(struct ptlrpc_bulk_desc *desc)
 934 {
 935         unstable_page_accounting(desc, 1);
 936 }
 937
 938 static inline void dec_unstable_page_accounting(struct ptlrpc_bulk_desc *desc)
 939 {
 940         unstable_page_accounting(desc, -1);
 941 }
 942
 943 /**
 944  * Performs "unstable" page accounting. This function balances the
 945  * increment operations performed in osc_inc_unstable_pages. It is
 946  * registered as the RPC request callback, and is executed when the
 947  * bulk RPC is committed on the server. Thus at this point, the pages
 948  * involved in the bulk transfer are no longer considered unstable.
 949  *
 950  * If this function is called, the request should have been committed
 951  * or req:rq_unstable must have been set; it implies that the unstable
 952  * statistic have been added.
 953  */
 954 void osc_dec_unstable_pages(struct ptlrpc_request *req)
 955 {
 956         struct ptlrpc_bulk_desc *desc       = req->rq_bulk;
 957         struct client_obd       *cli        = &req->rq_import->imp_obd->u.cli;
 958         int                      page_count = desc->bd_iov_count;
 959         long                     unstable_count;
 960
 961         LASSERT(page_count >= 0);
 962         dec_unstable_page_accounting(desc);
 963
 964         unstable_count = atomic_long_sub_return(page_count,
 965                                                 &cli->cl_unstable_count);
 966         LASSERT(unstable_count >= 0);
 967
 968         unstable_count = atomic_long_sub_return(page_count,
 969                                            &cli->cl_cache->ccc_unstable_nr);
 970         LASSERT(unstable_count >= 0);
 971         if (unstable_count == 0)
 972                 wake_up_all(&cli->cl_cache->ccc_unstable_waitq);
 973
 974         if (osc_cache_too_much(cli))
 975                 (void)ptlrpcd_queue_work(cli->cl_lru_work);
 976 }
 977
 978 /**
 979  * "unstable" page accounting. See: osc_dec_unstable_pages.
 980  */
 981 void osc_inc_unstable_pages(struct ptlrpc_request *req)
 982 {
 983         struct ptlrpc_bulk_desc *desc = req->rq_bulk;
 984         struct client_obd       *cli  = &req->rq_import->imp_obd->u.cli;
 985         long                     page_count = desc->bd_iov_count;
 986
 987         /* No unstable page tracking */
 988         if (cli->cl_cache == NULL || !cli->cl_cache->ccc_unstable_check)
 989                 return;
 990
 991         add_unstable_page_accounting(desc);
 992         atomic_long_add(page_count, &cli->cl_unstable_count);
 993         atomic_long_add(page_count, &cli->cl_cache->ccc_unstable_nr);
 994
 995         /* If the request has already been committed (i.e. brw_commit
 996          * called via rq_commit_cb), we need to undo the unstable page
 997          * increments we just performed because rq_commit_cb wont be
 998          * called again. */
 999         spin_lock(&req->rq_lock);
1000         if (unlikely(req->rq_committed)) {
1001                 spin_unlock(&req->rq_lock);
1002
1003                 osc_dec_unstable_pages(req);
1004         } else {
1005                 req->rq_unstable = 1;
1006                 spin_unlock(&req->rq_lock);
1007         }
1008 }
1009
1010 /**
1011  * Check if it piggybacks SOFT_SYNC flag to OST from this OSC.
1012  * This function will be called by every BRW RPC so it's critical
1013  * to make this function fast.
1014  */
1015 bool osc_over_unstable_soft_limit(struct client_obd *cli)
1016 {
1017         long unstable_nr, osc_unstable_count;
1018
1019         /* Can't check cli->cl_unstable_count, therefore, no soft limit */
1020         if (cli->cl_cache == NULL || !cli->cl_cache->ccc_unstable_check)
1021                 return false;
1022
1023         osc_unstable_count = atomic_long_read(&cli->cl_unstable_count);
1024         unstable_nr = atomic_long_read(&cli->cl_cache->ccc_unstable_nr);
1025
1026         CDEBUG(D_CACHE,
1027                "%s: cli: %p unstable pages: %lu, osc unstable pages: %lu\n",
1028                cli->cl_import->imp_obd->obd_name, cli,
1029                unstable_nr, osc_unstable_count);
1030
1031         /* If the LRU slots are in shortage - 25% remaining AND this OSC
1032          * has one full RPC window of unstable pages, it's a good chance
1033          * to piggyback a SOFT_SYNC flag.
1034          * Please notice that the OST won't take immediate response for the
1035          * SOFT_SYNC request so active OSCs will have more chance to carry
1036          * the flag, this is reasonable. */
1037         return unstable_nr > cli->cl_cache->ccc_lru_max >> 2 &&
1038                osc_unstable_count > cli->cl_max_pages_per_rpc *
1039                                     cli->cl_max_rpcs_in_flight;
1040 }
1041
1042 /** @} osc */