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< "LPD64" %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 #if 0
 514         } else if (pages >= budget * 2)
 515                 return lru_shrink_min;
 516 #endif
 517         }
 518         return 0;
 519 }
 520
 521 int lru_queue_work(const struct lu_env *env, void *data)
 522 {
 523         struct client_obd *cli = data;
 524
 525         CDEBUG(D_CACHE, "Run LRU work for client obd %p.\n", cli);
 526
 527         if (osc_cache_too_much(cli))
 528                 osc_lru_shrink(env, cli, lru_shrink_max, true);
 529
 530         RETURN(0);
 531 }
 532
 533 void osc_lru_add_batch(struct client_obd *cli, struct list_head *plist)
 534 {
 535         struct list_head lru = LIST_HEAD_INIT(lru);
 536         struct osc_async_page *oap;
 537         long npages = 0;
 538
 539         list_for_each_entry(oap, plist, oap_pending_item) {
 540                 struct osc_page *opg = oap2osc_page(oap);
 541
 542                 if (!opg->ops_in_lru)
 543                         continue;
 544
 545                 ++npages;
 546                 LASSERT(list_empty(&opg->ops_lru));
 547                 list_add(&opg->ops_lru, &lru);
 548         }
 549
 550         if (npages > 0) {
 551                 spin_lock(&cli->cl_lru_list_lock);
 552                 list_splice_tail(&lru, &cli->cl_lru_list);
 553                 atomic_long_sub(npages, &cli->cl_lru_busy);
 554                 atomic_long_add(npages, &cli->cl_lru_in_list);
 555                 spin_unlock(&cli->cl_lru_list_lock);
 556
 557                 /* XXX: May set force to be true for better performance */
 558                 if (osc_cache_too_much(cli))
 559                         (void)ptlrpcd_queue_work(cli->cl_lru_work);
 560         }
 561 }
 562
 563 static void __osc_lru_del(struct client_obd *cli, struct osc_page *opg)
 564 {
 565         LASSERT(atomic_long_read(&cli->cl_lru_in_list) > 0);
 566         list_del_init(&opg->ops_lru);
 567         atomic_long_dec(&cli->cl_lru_in_list);
 568 }
 569
 570 /**
 571  * Page is being destroyed. The page may be not in LRU list, if the transfer
 572  * has never finished(error occurred).
 573  */
 574 static void osc_lru_del(struct client_obd *cli, struct osc_page *opg)
 575 {
 576         if (opg->ops_in_lru) {
 577                 spin_lock(&cli->cl_lru_list_lock);
 578                 if (!list_empty(&opg->ops_lru)) {
 579                         __osc_lru_del(cli, opg);
 580                 } else {
 581                         LASSERT(atomic_long_read(&cli->cl_lru_busy) > 0);
 582                         atomic_long_dec(&cli->cl_lru_busy);
 583                 }
 584                 spin_unlock(&cli->cl_lru_list_lock);
 585
 586                 atomic_long_inc(cli->cl_lru_left);
 587                 /* this is a great place to release more LRU pages if
 588                  * this osc occupies too many LRU pages and kernel is
 589                  * stealing one of them. */
 590                 if (!memory_pressure_get())
 591                         (void)ptlrpcd_queue_work(cli->cl_lru_work);
 592                 wake_up(&osc_lru_waitq);
 593         } else {
 594                 LASSERT(list_empty(&opg->ops_lru));
 595         }
 596 }
 597
 598 /**
 599  * Delete page from LRUlist for redirty.
 600  */
 601 static void osc_lru_use(struct client_obd *cli, struct osc_page *opg)
 602 {
 603         /* If page is being transferred for the first time,
 604          * ops_lru should be empty */
 605         if (opg->ops_in_lru && !list_empty(&opg->ops_lru)) {
 606                 spin_lock(&cli->cl_lru_list_lock);
 607                 __osc_lru_del(cli, opg);
 608                 spin_unlock(&cli->cl_lru_list_lock);
 609                 atomic_long_inc(&cli->cl_lru_busy);
 610         }
 611 }
 612
 613 static void discard_pagevec(const struct lu_env *env, struct cl_io *io,
 614                                 struct cl_page **pvec, int max_index)
 615 {
 616         int i;
 617
 618         for (i = 0; i < max_index; i++) {
 619                 struct cl_page *page = pvec[i];
 620
 621                 LASSERT(cl_page_is_owned(page, io));
 622                 cl_page_discard(env, io, page);
 623                 cl_page_disown(env, io, page);
 624                 cl_page_put(env, page);
 625
 626                 pvec[i] = NULL;
 627         }
 628 }
 629
 630 /**
 631  * Check if a cl_page can be released, i.e, it's not being used.
 632  *
 633  * If unstable account is turned on, bulk transfer may hold one refcount
 634  * for recovery so we need to check vmpage refcount as well; otherwise,
 635  * even we can destroy cl_page but the corresponding vmpage can't be reused.
 636  */
 637 static inline bool lru_page_busy(struct client_obd *cli, struct cl_page *page)
 638 {
 639         if (cl_page_in_use_noref(page))
 640                 return true;
 641
 642         if (cli->cl_cache->ccc_unstable_check) {
 643                 struct page *vmpage = cl_page_vmpage(page);
 644
 645                 /* vmpage have two known users: cl_page and VM page cache */
 646                 if (page_count(vmpage) - page_mapcount(vmpage) > 2)
 647                         return true;
 648         }
 649         return false;
 650 }
 651
 652 /**
 653  * Drop @target of pages from LRU at most.
 654  */
 655 long osc_lru_shrink(const struct lu_env *env, struct client_obd *cli,
 656                    long target, bool force)
 657 {
 658         struct cl_io *io;
 659         struct cl_object *clobj = NULL;
 660         struct cl_page **pvec;
 661         struct osc_page *opg;
 662         long count = 0;
 663         int maxscan = 0;
 664         int index = 0;
 665         int rc = 0;
 666         ENTRY;
 667
 668         LASSERT(atomic_long_read(&cli->cl_lru_in_list) >= 0);
 669         if (atomic_long_read(&cli->cl_lru_in_list) == 0 || target <= 0)
 670                 RETURN(0);
 671
 672         if (!force) {
 673                 if (atomic_read(&cli->cl_lru_shrinkers) > 0)
 674                         RETURN(-EBUSY);
 675
 676                 if (atomic_inc_return(&cli->cl_lru_shrinkers) > 1) {
 677                         atomic_dec(&cli->cl_lru_shrinkers);
 678                         RETURN(-EBUSY);
 679                 }
 680         } else {
 681                 atomic_inc(&cli->cl_lru_shrinkers);
 682         }
 683
 684         pvec = (struct cl_page **)osc_env_info(env)->oti_pvec;
 685         io = &osc_env_info(env)->oti_io;
 686
 687         spin_lock(&cli->cl_lru_list_lock);
 688         maxscan = min(target << 1, atomic_long_read(&cli->cl_lru_in_list));
 689         while (!list_empty(&cli->cl_lru_list)) {
 690                 struct cl_page *page;
 691                 bool will_free = false;
 692
 693                 if (--maxscan < 0)
 694                         break;
 695
 696                 opg = list_entry(cli->cl_lru_list.next, struct osc_page,
 697                                  ops_lru);
 698                 page = opg->ops_cl.cpl_page;
 699                 if (lru_page_busy(cli, page)) {
 700                         list_move_tail(&opg->ops_lru, &cli->cl_lru_list);
 701                         continue;
 702                 }
 703
 704                 LASSERT(page->cp_obj != NULL);
 705                 if (clobj != page->cp_obj) {
 706                         struct cl_object *tmp = page->cp_obj;
 707
 708                         cl_object_get(tmp);
 709                         spin_unlock(&cli->cl_lru_list_lock);
 710
 711                         if (clobj != NULL) {
 712                                 discard_pagevec(env, io, pvec, index);
 713                                 index = 0;
 714
 715                                 cl_io_fini(env, io);
 716                                 cl_object_put(env, clobj);
 717                                 clobj = NULL;
 718                         }
 719
 720                         clobj = tmp;
 721                         io->ci_obj = clobj;
 722                         io->ci_ignore_layout = 1;
 723                         rc = cl_io_init(env, io, CIT_MISC, clobj);
 724
 725                         spin_lock(&cli->cl_lru_list_lock);
 726
 727                         if (rc != 0)
 728                                 break;
 729
 730                         ++maxscan;
 731                         continue;
 732                 }
 733
 734                 if (cl_page_own_try(env, io, page) == 0) {
 735                         if (!lru_page_busy(cli, page)) {
 736                                 /* remove it from lru list earlier to avoid
 737                                  * lock contention */
 738                                 __osc_lru_del(cli, opg);
 739                                 opg->ops_in_lru = 0; /* will be discarded */
 740
 741                                 cl_page_get(page);
 742                                 will_free = true;
 743                         } else {
 744                                 cl_page_disown(env, io, page);
 745                         }
 746                 }
 747
 748                 if (!will_free) {
 749                         list_move_tail(&opg->ops_lru, &cli->cl_lru_list);
 750                         continue;
 751                 }
 752
 753                 /* Don't discard and free the page with cl_lru_list held */
 754                 pvec[index++] = page;
 755                 if (unlikely(index == OTI_PVEC_SIZE)) {
 756                         spin_unlock(&cli->cl_lru_list_lock);
 757                         discard_pagevec(env, io, pvec, index);
 758                         index = 0;
 759
 760                         spin_lock(&cli->cl_lru_list_lock);
 761                 }
 762
 763                 if (++count >= target)
 764                         break;
 765         }
 766         spin_unlock(&cli->cl_lru_list_lock);
 767
 768         if (clobj != NULL) {
 769                 discard_pagevec(env, io, pvec, index);
 770
 771                 cl_io_fini(env, io);
 772                 cl_object_put(env, clobj);
 773         }
 774
 775         atomic_dec(&cli->cl_lru_shrinkers);
 776         if (count > 0) {
 777                 atomic_long_add(count, cli->cl_lru_left);
 778                 wake_up_all(&osc_lru_waitq);
 779         }
 780         RETURN(count > 0 ? count : rc);
 781 }
 782
 783 long osc_lru_reclaim(struct client_obd *cli)
 784 {
 785         struct cl_env_nest nest;
 786         struct lu_env *env;
 787         struct cl_client_cache *cache = cli->cl_cache;
 788         long rc = 0;
 789         int max_scans;
 790         ENTRY;
 791
 792         LASSERT(cache != NULL);
 793         LASSERT(!list_empty(&cache->ccc_lru));
 794
 795         env = cl_env_nested_get(&nest);
 796         if (IS_ERR(env))
 797                 RETURN(rc);
 798
 799         rc = osc_lru_shrink(env, cli, osc_cache_too_much(cli), false);
 800         if (rc != 0) {
 801                 if (rc == -EBUSY)
 802                         rc = 0;
 803
 804                 CDEBUG(D_CACHE, "%s: Free %ld pages from own LRU: %p.\n",
 805                         cli->cl_import->imp_obd->obd_name, rc, cli);
 806                 GOTO(out, rc);
 807         }
 808
 809         CDEBUG(D_CACHE, "%s: cli %p no free slots, pages: %ld, busy: %ld.\n",
 810                 cli->cl_import->imp_obd->obd_name, cli,
 811                 atomic_long_read(&cli->cl_lru_in_list),
 812                 atomic_long_read(&cli->cl_lru_busy));
 813
 814         /* Reclaim LRU slots from other client_obd as it can't free enough
 815          * from its own. This should rarely happen. */
 816         spin_lock(&cache->ccc_lru_lock);
 817         cache->ccc_lru_shrinkers++;
 818         list_move_tail(&cli->cl_lru_osc, &cache->ccc_lru);
 819
 820         max_scans = atomic_read(&cache->ccc_users) - 2;
 821         while (--max_scans > 0 && !list_empty(&cache->ccc_lru)) {
 822                 cli = list_entry(cache->ccc_lru.next, struct client_obd,
 823                                  cl_lru_osc);
 824
 825                 CDEBUG(D_CACHE, "%s: cli %p LRU pages: %ld, busy: %ld.\n",
 826                         cli->cl_import->imp_obd->obd_name, cli,
 827                         atomic_long_read(&cli->cl_lru_in_list),
 828                         atomic_long_read(&cli->cl_lru_busy));
 829
 830                 list_move_tail(&cli->cl_lru_osc, &cache->ccc_lru);
 831                 if (osc_cache_too_much(cli) > 0) {
 832                         spin_unlock(&cache->ccc_lru_lock);
 833
 834                         rc = osc_lru_shrink(env, cli, osc_cache_too_much(cli),
 835                                             true);
 836                         spin_lock(&cache->ccc_lru_lock);
 837                         if (rc != 0)
 838                                 break;
 839                 }
 840         }
 841         spin_unlock(&cache->ccc_lru_lock);
 842
 843 out:
 844         cl_env_nested_put(&nest, env);
 845         CDEBUG(D_CACHE, "%s: cli %p freed %ld pages.\n",
 846                 cli->cl_import->imp_obd->obd_name, cli, rc);
 847         return rc;
 848 }
 849
 850 /**
 851  * osc_lru_reserve() is called to reserve an LRU slot for a cl_page.
 852  *
 853  * Usually the LRU slots are reserved in osc_io_iter_rw_init().
 854  * Only in the case that the LRU slots are in extreme shortage, it should
 855  * have reserved enough slots for an IO.
 856  */
 857 static int osc_lru_reserve(const struct lu_env *env, struct osc_object *obj,
 858                            struct osc_page *opg)
 859 {
 860         struct l_wait_info lwi = LWI_INTR(LWI_ON_SIGNAL_NOOP, NULL);
 861         struct osc_io *oio = osc_env_io(env);
 862         struct client_obd *cli = osc_cli(obj);
 863         int rc = 0;
 864         ENTRY;
 865
 866         if (cli->cl_cache == NULL) /* shall not be in LRU */
 867                 RETURN(0);
 868
 869         if (oio->oi_lru_reserved > 0) {
 870                 --oio->oi_lru_reserved;
 871                 goto out;
 872         }
 873
 874         LASSERT(atomic_long_read(cli->cl_lru_left) >= 0);
 875         while (!atomic_long_add_unless(cli->cl_lru_left, -1, 0)) {
 876
 877                 /* run out of LRU spaces, try to drop some by itself */
 878                 rc = osc_lru_reclaim(cli);
 879                 if (rc < 0)
 880                         break;
 881                 if (rc > 0)
 882                         continue;
 883
 884                 cond_resched();
 885                 rc = l_wait_event(osc_lru_waitq,
 886                                 atomic_long_read(cli->cl_lru_left) > 0,
 887                                 &lwi);
 888                 if (rc < 0)
 889                         break;
 890         }
 891
 892 out:
 893         if (rc >= 0) {
 894                 atomic_long_inc(&cli->cl_lru_busy);
 895                 opg->ops_in_lru = 1;
 896                 rc = 0;
 897         }
 898
 899         RETURN(rc);
 900 }
 901
 902 /**
 903  * Atomic operations are expensive. We accumulate the accounting for the
 904  * same page zone to get better performance.
 905  * In practice this can work pretty good because the pages in the same RPC
 906  * are likely from the same page zone.
 907  */
 908 static inline void unstable_page_accounting(struct ptlrpc_bulk_desc *desc,
 909                                             int factor)
 910 {
 911         int page_count = desc->bd_iov_count;
 912         void *zone = NULL;
 913         int count = 0;
 914         int i;
 915
 916         for (i = 0; i < page_count; i++) {
 917                 void *pz = page_zone(desc->bd_iov[i].kiov_page);
 918
 919                 if (likely(pz == zone)) {
 920                         ++count;
 921                         continue;
 922                 }
 923
 924                 if (count > 0) {
 925                         mod_zone_page_state(zone, NR_UNSTABLE_NFS,
 926                                             factor * count);
 927                         count = 0;
 928                 }
 929                 zone = pz;
 930                 ++count;
 931         }
 932         if (count > 0)
 933                 mod_zone_page_state(zone, NR_UNSTABLE_NFS, factor * count);
 934 }
 935
 936 static inline void add_unstable_page_accounting(struct ptlrpc_bulk_desc *desc)
 937 {
 938         unstable_page_accounting(desc, 1);
 939 }
 940
 941 static inline void dec_unstable_page_accounting(struct ptlrpc_bulk_desc *desc)
 942 {
 943         unstable_page_accounting(desc, -1);
 944 }
 945
 946 /**
 947  * Performs "unstable" page accounting. This function balances the
 948  * increment operations performed in osc_inc_unstable_pages. It is
 949  * registered as the RPC request callback, and is executed when the
 950  * bulk RPC is committed on the server. Thus at this point, the pages
 951  * involved in the bulk transfer are no longer considered unstable.
 952  *
 953  * If this function is called, the request should have been committed
 954  * or req:rq_unstable must have been set; it implies that the unstable
 955  * statistic have been added.
 956  */
 957 void osc_dec_unstable_pages(struct ptlrpc_request *req)
 958 {
 959         struct ptlrpc_bulk_desc *desc       = req->rq_bulk;
 960         struct client_obd       *cli        = &req->rq_import->imp_obd->u.cli;
 961         int                      page_count = desc->bd_iov_count;
 962         long                     unstable_count;
 963
 964         LASSERT(page_count >= 0);
 965         dec_unstable_page_accounting(desc);
 966
 967         unstable_count = atomic_long_sub_return(page_count,
 968                                                 &cli->cl_unstable_count);
 969         LASSERT(unstable_count >= 0);
 970
 971         unstable_count = atomic_long_sub_return(page_count,
 972                                            &cli->cl_cache->ccc_unstable_nr);
 973         LASSERT(unstable_count >= 0);
 974         if (unstable_count == 0)
 975                 wake_up_all(&cli->cl_cache->ccc_unstable_waitq);
 976
 977         if (osc_cache_too_much(cli))
 978                 (void)ptlrpcd_queue_work(cli->cl_lru_work);
 979 }
 980
 981 /**
 982  * "unstable" page accounting. See: osc_dec_unstable_pages.
 983  */
 984 void osc_inc_unstable_pages(struct ptlrpc_request *req)
 985 {
 986         struct ptlrpc_bulk_desc *desc = req->rq_bulk;
 987         struct client_obd       *cli  = &req->rq_import->imp_obd->u.cli;
 988         long                     page_count = desc->bd_iov_count;
 989
 990         /* No unstable page tracking */
 991         if (cli->cl_cache == NULL || !cli->cl_cache->ccc_unstable_check)
 992                 return;
 993
 994         add_unstable_page_accounting(desc);
 995         atomic_long_add(page_count, &cli->cl_unstable_count);
 996         atomic_long_add(page_count, &cli->cl_cache->ccc_unstable_nr);
 997
 998         /* If the request has already been committed (i.e. brw_commit
 999          * called via rq_commit_cb), we need to undo the unstable page
1000          * increments we just performed because rq_commit_cb wont be
1001          * called again. */
1002         spin_lock(&req->rq_lock);
1003         if (unlikely(req->rq_committed)) {
1004                 spin_unlock(&req->rq_lock);
1005
1006                 osc_dec_unstable_pages(req);
1007         } else {
1008                 req->rq_unstable = 1;
1009                 spin_unlock(&req->rq_lock);
1010         }
1011 }
1012
1013 /**
1014  * Check if it piggybacks SOFT_SYNC flag to OST from this OSC.
1015  * This function will be called by every BRW RPC so it's critical
1016  * to make this function fast.
1017  */
1018 bool osc_over_unstable_soft_limit(struct client_obd *cli)
1019 {
1020         long unstable_nr, osc_unstable_count;
1021
1022         /* Can't check cli->cl_unstable_count, therefore, no soft limit */
1023         if (cli->cl_cache == NULL || !cli->cl_cache->ccc_unstable_check)
1024                 return false;
1025
1026         osc_unstable_count = atomic_long_read(&cli->cl_unstable_count);
1027         unstable_nr = atomic_long_read(&cli->cl_cache->ccc_unstable_nr);
1028
1029         CDEBUG(D_CACHE,
1030                "%s: cli: %p unstable pages: %lu, osc unstable pages: %lu\n",
1031                cli->cl_import->imp_obd->obd_name, cli,
1032                unstable_nr, osc_unstable_count);
1033
1034         /* If the LRU slots are in shortage - 25% remaining AND this OSC
1035          * has one full RPC window of unstable pages, it's a good chance
1036          * to piggyback a SOFT_SYNC flag.
1037          * Please notice that the OST won't take immediate response for the
1038          * SOFT_SYNC request so active OSCs will have more chance to carry
1039          * the flag, this is reasonable. */
1040         return unstable_nr > cli->cl_cache->ccc_lru_max >> 2 &&
1041                osc_unstable_count > cli->cl_max_pages_per_rpc *
1042                                     cli->cl_max_rpcs_in_flight;
1043 }
1044
1045 /** @} osc */