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.gnu.org/licenses/gpl-2.0.html
  19  *
  20  * GPL HEADER END
  21  */
  22 /*
  23  * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  24  * Use is subject to license terms.
  25  *
  26  * Copyright (c) 2011, 2017, Intel Corporation.
  27  */
  28 /*
  29  * This file is part of Lustre, http://www.lustre.org/
  30  * Lustre is a trademark of Sun Microsystems, Inc.
  31  *
  32  * Implementation of cl_page for OSC layer.
  33  *
  34  *   Author: Nikita Danilov <nikita.danilov@sun.com>
  35  *   Author: Jinshan Xiong <jinshan.xiong@intel.com>
  36  */
  37
  38 #define DEBUG_SUBSYSTEM S_OSC
  39 #include <lustre_osc.h>
  40
  41 #include "osc_internal.h"
  42
  43 static void osc_lru_del(struct client_obd *cli, struct osc_page *opg);
  44 static void osc_lru_use(struct client_obd *cli, struct osc_page *opg);
  45 static int osc_lru_alloc(const struct lu_env *env, struct client_obd *cli,
  46                          struct osc_page *opg);
  47
  48 /** \addtogroup osc
  49  *  @{
  50  */
  51
  52 /*
  53  * Page operations.
  54  */
  55 static void osc_page_transfer_get(struct osc_page *opg, const char *label)
  56 {
  57         struct cl_page *page = opg->ops_cl.cpl_page;
  58
  59         LASSERT(!opg->ops_transfer_pinned);
  60         cl_page_get(page);
  61         lu_ref_add_atomic(&page->cp_reference, label, page);
  62         opg->ops_transfer_pinned = 1;
  63 }
  64
  65 static void osc_page_transfer_put(const struct lu_env *env,
  66                                   struct osc_page *opg)
  67 {
  68         struct cl_page *page = opg->ops_cl.cpl_page;
  69
  70         if (opg->ops_transfer_pinned) {
  71                 opg->ops_transfer_pinned = 0;
  72                 lu_ref_del(&page->cp_reference, "transfer", page);
  73                 cl_page_put(env, page);
  74         }
  75 }
  76
  77 /**
  78  * This is called once for every page when it is submitted for a transfer
  79  * either opportunistic (osc_page_cache_add()), or immediate
  80  * (osc_page_submit()).
  81  */
  82 static void osc_page_transfer_add(const struct lu_env *env,
  83                                   struct osc_page *opg, enum cl_req_type crt)
  84 {
  85         struct osc_object *obj = cl2osc(opg->ops_cl.cpl_obj);
  86
  87         osc_lru_use(osc_cli(obj), opg);
  88 }
  89
  90 int osc_page_cache_add(const struct lu_env *env,
  91                         const struct cl_page_slice *slice, struct cl_io *io)
  92 {
  93         struct osc_page *opg = cl2osc_page(slice);
  94         int result;
  95         ENTRY;
  96
  97         osc_page_transfer_get(opg, "transfer\0cache");
  98         result = osc_queue_async_io(env, io, opg);
  99         if (result != 0)
 100                 osc_page_transfer_put(env, opg);
 101         else
 102                 osc_page_transfer_add(env, opg, CRT_WRITE);
 103
 104         RETURN(result);
 105 }
 106
 107 void osc_index2policy(union ldlm_policy_data *policy,
 108                       const struct cl_object *obj, pgoff_t start, pgoff_t end)
 109 {
 110         memset(policy, 0, sizeof *policy);
 111         policy->l_extent.start = cl_offset(obj, start);
 112         policy->l_extent.end   = cl_offset(obj, end + 1) - 1;
 113 }
 114
 115 static const char *osc_list(struct list_head *head)
 116 {
 117         return list_empty(head) ? "-" : "+";
 118 }
 119
 120 static inline s64 osc_submit_duration(struct osc_page *opg)
 121 {
 122         if (ktime_to_ns(opg->ops_submit_time) == 0)
 123                 return 0;
 124
 125         return ktime_ms_delta(ktime_get(), opg->ops_submit_time);
 126 }
 127
 128 static int osc_page_print(const struct lu_env *env,
 129                           const struct cl_page_slice *slice,
 130                           void *cookie, lu_printer_t printer)
 131 {
 132         struct osc_page       *opg = cl2osc_page(slice);
 133         struct osc_async_page *oap = &opg->ops_oap;
 134         struct osc_object     *obj = cl2osc(slice->cpl_obj);
 135         struct client_obd     *cli = &osc_export(obj)->exp_obd->u.cli;
 136
 137         return (*printer)(env, cookie, LUSTRE_OSC_NAME"-page@%p %lu: "
 138                           "1< %#x %d %u %s %s > "
 139                           "2< %lld %u %u %#x %#x | %p %p %p > "
 140                           "3< %d %lld %d > "
 141                           "4< %d %d %d %lu %s | %s %s %s %s > "
 142                           "5< %s %s %s %s | %d %s | %d %s %s>\n",
 143                           opg, osc_index(opg),
 144                           /* 1 */
 145                           oap->oap_magic, oap->oap_cmd,
 146                           oap->oap_interrupted,
 147                           osc_list(&oap->oap_pending_item),
 148                           osc_list(&oap->oap_rpc_item),
 149                           /* 2 */
 150                           oap->oap_obj_off, oap->oap_page_off, oap->oap_count,
 151                           oap->oap_async_flags, oap->oap_brw_flags,
 152                           oap->oap_request, oap->oap_cli, obj,
 153                           /* 3 */
 154                           opg->ops_transfer_pinned,
 155                           osc_submit_duration(opg), opg->ops_srvlock,
 156                           /* 4 */
 157                           cli->cl_r_in_flight, cli->cl_w_in_flight,
 158                           cli->cl_max_rpcs_in_flight,
 159                           cli->cl_avail_grant,
 160                           osc_list(&cli->cl_cache_waiters),
 161                           osc_list(&cli->cl_loi_ready_list),
 162                           osc_list(&cli->cl_loi_hp_ready_list),
 163                           osc_list(&cli->cl_loi_write_list),
 164                           osc_list(&cli->cl_loi_read_list),
 165                           /* 5 */
 166                           osc_list(&obj->oo_ready_item),
 167                           osc_list(&obj->oo_hp_ready_item),
 168                           osc_list(&obj->oo_write_item),
 169                           osc_list(&obj->oo_read_item),
 170                           atomic_read(&obj->oo_nr_reads),
 171                           osc_list(&obj->oo_reading_exts),
 172                           atomic_read(&obj->oo_nr_writes),
 173                           osc_list(&obj->oo_hp_exts),
 174                           osc_list(&obj->oo_urgent_exts));
 175 }
 176
 177 static void osc_page_delete(const struct lu_env *env,
 178                             const struct cl_page_slice *slice)
 179 {
 180         struct osc_page   *opg = cl2osc_page(slice);
 181         struct osc_object *obj = cl2osc(opg->ops_cl.cpl_obj);
 182         int rc;
 183
 184         ENTRY;
 185         CDEBUG(D_TRACE, "%p\n", opg);
 186         osc_page_transfer_put(env, opg);
 187         rc = osc_teardown_async_page(env, obj, opg);
 188         if (rc) {
 189                 CL_PAGE_DEBUG(D_ERROR, env, slice->cpl_page,
 190                               "Trying to teardown failed: %d\n", rc);
 191                 LASSERT(0);
 192         }
 193
 194         osc_lru_del(osc_cli(obj), opg);
 195
 196         if (slice->cpl_page->cp_type == CPT_CACHEABLE) {
 197                 void *value = NULL;
 198
 199                 spin_lock(&obj->oo_tree_lock);
 200                 if (opg->ops_intree) {
 201                         value = radix_tree_delete(&obj->oo_tree,
 202                                                   osc_index(opg));
 203                         if (value != NULL) {
 204                                 --obj->oo_npages;
 205                                 opg->ops_intree = 0;
 206                         }
 207                 }
 208                 spin_unlock(&obj->oo_tree_lock);
 209
 210                 LASSERT(ergo(value != NULL, value == opg));
 211         }
 212
 213         EXIT;
 214 }
 215
 216 static void osc_page_clip(const struct lu_env *env,
 217                           const struct cl_page_slice *slice,
 218                           int from, int to)
 219 {
 220         struct osc_page       *opg = cl2osc_page(slice);
 221         struct osc_async_page *oap = &opg->ops_oap;
 222
 223         opg->ops_from = from;
 224         opg->ops_to   = to;
 225         spin_lock(&oap->oap_lock);
 226         oap->oap_async_flags |= ASYNC_COUNT_STABLE;
 227         spin_unlock(&oap->oap_lock);
 228 }
 229
 230 static int osc_page_cancel(const struct lu_env *env,
 231                            const struct cl_page_slice *slice)
 232 {
 233         struct osc_page *opg = cl2osc_page(slice);
 234         int rc = 0;
 235
 236         /* Check if the transferring against this page
 237          * is completed, or not even queued. */
 238         if (opg->ops_transfer_pinned)
 239                 /* FIXME: may not be interrupted.. */
 240                 rc = osc_cancel_async_page(env, opg);
 241         LASSERT(ergo(rc == 0, opg->ops_transfer_pinned == 0));
 242         return rc;
 243 }
 244
 245 static int osc_page_flush(const struct lu_env *env,
 246                           const struct cl_page_slice *slice,
 247                           struct cl_io *io)
 248 {
 249         struct osc_page *opg = cl2osc_page(slice);
 250         int rc = 0;
 251         ENTRY;
 252         rc = osc_flush_async_page(env, io, opg);
 253         RETURN(rc);
 254 }
 255
 256 static void osc_page_touch(const struct lu_env *env,
 257                           const struct cl_page_slice *slice, size_t to)
 258 {
 259         struct osc_page *opg = cl2osc_page(slice);
 260         struct cl_object *obj = opg->ops_cl.cpl_obj;
 261
 262         osc_page_touch_at(env, obj, osc_index(opg), to);
 263 }
 264
 265 static const struct cl_page_operations osc_page_ops = {
 266         .cpo_print         = osc_page_print,
 267         .cpo_delete        = osc_page_delete,
 268         .cpo_clip           = osc_page_clip,
 269         .cpo_cancel         = osc_page_cancel,
 270         .cpo_flush          = osc_page_flush,
 271         .cpo_page_touch    = osc_page_touch,
 272 };
 273
 274 int osc_page_init(const struct lu_env *env, struct cl_object *obj,
 275                   struct cl_page *page, pgoff_t index)
 276 {
 277         struct osc_object *osc = cl2osc(obj);
 278         struct osc_page   *opg = cl_object_page_slice(obj, page);
 279         struct osc_io *oio = osc_env_io(env);
 280         int result;
 281
 282         opg->ops_from = 0;
 283         opg->ops_to   = PAGE_SIZE;
 284
 285         INIT_LIST_HEAD(&opg->ops_lru);
 286
 287         result = osc_prep_async_page(osc, opg, page->cp_vmpage,
 288                                      cl_offset(obj, index));
 289         if (result != 0)
 290                 return result;
 291
 292         opg->ops_srvlock = osc_io_srvlock(oio);
 293         cl_page_slice_add(page, &opg->ops_cl, obj, index,
 294                           &osc_page_ops);
 295
 296
 297         /* reserve an LRU space for this page */
 298         if (page->cp_type == CPT_CACHEABLE) {
 299                 result = osc_lru_alloc(env, osc_cli(osc), opg);
 300                 if (result == 0) {
 301                         result = radix_tree_preload(GFP_NOFS);
 302                         if (result == 0) {
 303                                 spin_lock(&osc->oo_tree_lock);
 304                                 result = radix_tree_insert(&osc->oo_tree,
 305                                                            index, opg);
 306                                 if (result == 0) {
 307                                         ++osc->oo_npages;
 308                                         opg->ops_intree = 1;
 309                                 }
 310                                 spin_unlock(&osc->oo_tree_lock);
 311
 312                                 radix_tree_preload_end();
 313                         }
 314                 }
 315         }
 316
 317         return result;
 318 }
 319 EXPORT_SYMBOL(osc_page_init);
 320
 321 /**
 322  * Helper function called by osc_io_submit() for every page in an immediate
 323  * transfer (i.e., transferred synchronously).
 324  */
 325 void osc_page_submit(const struct lu_env *env, struct osc_page *opg,
 326                      enum cl_req_type crt, int brw_flags)
 327 {
 328         struct osc_io *oio = osc_env_io(env);
 329         struct osc_async_page *oap = &opg->ops_oap;
 330
 331         LASSERTF(oap->oap_magic == OAP_MAGIC, "Bad oap magic: oap %p, "
 332                  "magic 0x%x\n", oap, oap->oap_magic);
 333         LASSERT(oap->oap_async_flags & ASYNC_READY);
 334         LASSERT(oap->oap_async_flags & ASYNC_COUNT_STABLE);
 335
 336         oap->oap_cmd       = crt == CRT_WRITE ? OBD_BRW_WRITE : OBD_BRW_READ;
 337         oap->oap_page_off  = opg->ops_from;
 338         oap->oap_count     = opg->ops_to - opg->ops_from;
 339         oap->oap_brw_flags = OBD_BRW_SYNC | brw_flags;
 340
 341         if (oio->oi_cap_sys_resource) {
 342                 oap->oap_brw_flags |= OBD_BRW_NOQUOTA;
 343                 oap->oap_cmd |= OBD_BRW_NOQUOTA;
 344         }
 345
 346         opg->ops_submit_time = ktime_get();
 347         osc_page_transfer_get(opg, "transfer\0imm");
 348         osc_page_transfer_add(env, opg, crt);
 349 }
 350
 351 /* --------------- LRU page management ------------------ */
 352
 353 /* OSC is a natural place to manage LRU pages as applications are specialized
 354  * to write OSC by OSC. Ideally, if one OSC is used more frequently it should
 355  * occupy more LRU slots. On the other hand, we should avoid using up all LRU
 356  * slots (client_obd::cl_lru_left) otherwise process has to be put into sleep
 357  * for free LRU slots - this will be very bad so the algorithm requires each
 358  * OSC to free slots voluntarily to maintain a reasonable number of free slots
 359  * at any time.
 360  */
 361
 362 static DECLARE_WAIT_QUEUE_HEAD(osc_lru_waitq);
 363
 364 /**
 365  * LRU pages are freed in batch mode. OSC should at least free this
 366  * number of pages to avoid running out of LRU slots.
 367  */
 368 static inline int lru_shrink_min(struct client_obd *cli)
 369 {
 370         return cli->cl_max_pages_per_rpc * 2;
 371 }
 372
 373 /**
 374  * free this number at most otherwise it will take too long time to finsih.
 375  */
 376 static inline int lru_shrink_max(struct client_obd *cli)
 377 {
 378         return cli->cl_max_pages_per_rpc * cli->cl_max_rpcs_in_flight;
 379 }
 380
 381 /**
 382  * Check if we can free LRU slots from this OSC. If there exists LRU waiters,
 383  * we should free slots aggressively. In this way, slots are freed in a steady
 384  * step to maintain fairness among OSCs.
 385  *
 386  * Return how many LRU pages should be freed.
 387  */
 388 static int osc_cache_too_much(struct client_obd *cli)
 389 {
 390         struct cl_client_cache *cache = cli->cl_cache;
 391         long pages = atomic_long_read(&cli->cl_lru_in_list);
 392         unsigned long budget;
 393
 394         LASSERT(cache != NULL);
 395         budget = cache->ccc_lru_max / (atomic_read(&cache->ccc_users) - 2);
 396
 397         /* if it's going to run out LRU slots, we should free some, but not
 398          * too much to maintain faireness among OSCs. */
 399         if (atomic_long_read(cli->cl_lru_left) < cache->ccc_lru_max >> 2) {
 400                 if (pages >= budget)
 401                         return lru_shrink_max(cli);
 402                 else if (pages >= budget / 2)
 403                         return lru_shrink_min(cli);
 404         } else {
 405                 time64_t duration = ktime_get_real_seconds();
 406                 long timediff;
 407
 408                 /* knock out pages by duration of no IO activity */
 409                 duration -= cli->cl_lru_last_used;
 410                 /*
 411                  * The difference shouldn't be more than 70 years
 412                  * so we can safely case to a long. Round to
 413                  * approximately 1 minute.
 414                  */
 415                 timediff = (long)(duration >> 6);
 416                 if (timediff > 0 && pages >= budget / timediff)
 417                         return lru_shrink_min(cli);
 418         }
 419         return 0;
 420 }
 421
 422 int lru_queue_work(const struct lu_env *env, void *data)
 423 {
 424         struct client_obd *cli = data;
 425         int count;
 426
 427         CDEBUG(D_CACHE, "%s: run LRU work for client obd\n", cli_name(cli));
 428         count = osc_cache_too_much(cli);
 429         if (count > 0) {
 430                 int rc = osc_lru_shrink(env, cli, count, false);
 431
 432                 CDEBUG(D_CACHE, "%s: shrank %d/%d pages from client obd\n",
 433                        cli_name(cli), rc, count);
 434                 if (rc >= count) {
 435                         CDEBUG(D_CACHE, "%s: queue again\n", cli_name(cli));
 436                         ptlrpcd_queue_work(cli->cl_lru_work);
 437                 }
 438         }
 439
 440         RETURN(0);
 441 }
 442
 443 void osc_lru_add_batch(struct client_obd *cli, struct list_head *plist)
 444 {
 445         struct list_head lru = LIST_HEAD_INIT(lru);
 446         struct osc_async_page *oap;
 447         long npages = 0;
 448
 449         list_for_each_entry(oap, plist, oap_pending_item) {
 450                 struct osc_page *opg = oap2osc_page(oap);
 451
 452                 if (!opg->ops_in_lru)
 453                         continue;
 454
 455                 ++npages;
 456                 LASSERT(list_empty(&opg->ops_lru));
 457                 list_add(&opg->ops_lru, &lru);
 458         }
 459
 460         if (npages > 0) {
 461                 spin_lock(&cli->cl_lru_list_lock);
 462                 list_splice_tail(&lru, &cli->cl_lru_list);
 463                 atomic_long_sub(npages, &cli->cl_lru_busy);
 464                 atomic_long_add(npages, &cli->cl_lru_in_list);
 465                 cli->cl_lru_last_used = ktime_get_real_seconds();
 466                 spin_unlock(&cli->cl_lru_list_lock);
 467
 468                 if (waitqueue_active(&osc_lru_waitq))
 469                         (void)ptlrpcd_queue_work(cli->cl_lru_work);
 470         }
 471 }
 472
 473 static void __osc_lru_del(struct client_obd *cli, struct osc_page *opg)
 474 {
 475         LASSERT(atomic_long_read(&cli->cl_lru_in_list) > 0);
 476         list_del_init(&opg->ops_lru);
 477         atomic_long_dec(&cli->cl_lru_in_list);
 478 }
 479
 480 /**
 481  * Page is being destroyed. The page may be not in LRU list, if the transfer
 482  * has never finished(error occurred).
 483  */
 484 static void osc_lru_del(struct client_obd *cli, struct osc_page *opg)
 485 {
 486         if (opg->ops_in_lru) {
 487                 spin_lock(&cli->cl_lru_list_lock);
 488                 if (!list_empty(&opg->ops_lru)) {
 489                         __osc_lru_del(cli, opg);
 490                 } else {
 491                         LASSERT(atomic_long_read(&cli->cl_lru_busy) > 0);
 492                         atomic_long_dec(&cli->cl_lru_busy);
 493                 }
 494                 spin_unlock(&cli->cl_lru_list_lock);
 495
 496                 atomic_long_inc(cli->cl_lru_left);
 497                 /* this is a great place to release more LRU pages if
 498                  * this osc occupies too many LRU pages and kernel is
 499                  * stealing one of them. */
 500                 if (osc_cache_too_much(cli)) {
 501                         CDEBUG(D_CACHE, "%s: queue LRU work\n", cli_name(cli));
 502                         (void)ptlrpcd_queue_work(cli->cl_lru_work);
 503                 }
 504                 wake_up(&osc_lru_waitq);
 505         } else {
 506                 LASSERT(list_empty(&opg->ops_lru));
 507         }
 508 }
 509
 510 /**
 511  * Delete page from LRU list for redirty.
 512  */
 513 static void osc_lru_use(struct client_obd *cli, struct osc_page *opg)
 514 {
 515         /* If page is being transferred for the first time,
 516          * ops_lru should be empty */
 517         if (opg->ops_in_lru) {
 518                 if (list_empty(&opg->ops_lru))
 519                         return;
 520                 spin_lock(&cli->cl_lru_list_lock);
 521                 if (!list_empty(&opg->ops_lru)) {
 522                         __osc_lru_del(cli, opg);
 523                         atomic_long_inc(&cli->cl_lru_busy);
 524                 }
 525                 spin_unlock(&cli->cl_lru_list_lock);
 526         }
 527 }
 528
 529 static void discard_pagevec(const struct lu_env *env, struct cl_io *io,
 530                                 struct cl_page **pvec, int max_index)
 531 {
 532         struct pagevec *pagevec = &osc_env_info(env)->oti_pagevec;
 533         int i;
 534
 535         ll_pagevec_init(pagevec, 0);
 536         for (i = 0; i < max_index; i++) {
 537                 struct cl_page *page = pvec[i];
 538
 539                 LASSERT(cl_page_is_owned(page, io));
 540                 cl_page_delete(env, page);
 541                 cl_page_discard(env, io, page);
 542                 cl_page_disown(env, io, page);
 543                 cl_pagevec_put(env, page, pagevec);
 544
 545                 pvec[i] = NULL;
 546         }
 547         pagevec_release(pagevec);
 548 }
 549
 550 /**
 551  * Check if a cl_page can be released, i.e, it's not being used.
 552  *
 553  * If unstable account is turned on, bulk transfer may hold one refcount
 554  * for recovery so we need to check vmpage refcount as well; otherwise,
 555  * even we can destroy cl_page but the corresponding vmpage can't be reused.
 556  */
 557 static inline bool lru_page_busy(struct client_obd *cli, struct cl_page *page)
 558 {
 559         if (cl_page_in_use_noref(page))
 560                 return true;
 561
 562         if (cli->cl_cache->ccc_unstable_check) {
 563                 struct page *vmpage = cl_page_vmpage(page);
 564
 565                 /* vmpage have two known users: cl_page and VM page cache */
 566                 if (page_count(vmpage) - page_mapcount(vmpage) > 2)
 567                         return true;
 568         }
 569         return false;
 570 }
 571
 572 /**
 573  * Drop @target of pages from LRU at most.
 574  */
 575 long osc_lru_shrink(const struct lu_env *env, struct client_obd *cli,
 576                    long target, bool force)
 577 {
 578         struct cl_io *io;
 579         struct cl_object *clobj = NULL;
 580         struct cl_page **pvec;
 581         struct osc_page *opg;
 582         long count = 0;
 583         int maxscan = 0;
 584         int index = 0;
 585         int rc = 0;
 586         ENTRY;
 587
 588         LASSERT(atomic_long_read(&cli->cl_lru_in_list) >= 0);
 589         if (atomic_long_read(&cli->cl_lru_in_list) == 0 || target <= 0)
 590                 RETURN(0);
 591
 592         CDEBUG(D_CACHE, "%s: shrinkers: %d, force: %d\n",
 593                cli_name(cli), atomic_read(&cli->cl_lru_shrinkers), force);
 594         if (!force) {
 595                 if (atomic_read(&cli->cl_lru_shrinkers) > 0)
 596                         RETURN(-EBUSY);
 597
 598                 if (atomic_inc_return(&cli->cl_lru_shrinkers) > 1) {
 599                         atomic_dec(&cli->cl_lru_shrinkers);
 600                         RETURN(-EBUSY);
 601                 }
 602         } else {
 603                 atomic_inc(&cli->cl_lru_shrinkers);
 604         }
 605
 606         pvec = (struct cl_page **)osc_env_info(env)->oti_pvec;
 607         io = osc_env_thread_io(env);
 608
 609         spin_lock(&cli->cl_lru_list_lock);
 610         if (force)
 611                 cli->cl_lru_reclaim++;
 612         maxscan = min(target << 1, atomic_long_read(&cli->cl_lru_in_list));
 613         while (!list_empty(&cli->cl_lru_list)) {
 614                 struct cl_page *page;
 615                 bool will_free = false;
 616
 617                 if (!force && atomic_read(&cli->cl_lru_shrinkers) > 1)
 618                         break;
 619
 620                 if (--maxscan < 0)
 621                         break;
 622
 623                 opg = list_entry(cli->cl_lru_list.next, struct osc_page,
 624                                  ops_lru);
 625                 page = opg->ops_cl.cpl_page;
 626                 if (lru_page_busy(cli, page)) {
 627                         list_move_tail(&opg->ops_lru, &cli->cl_lru_list);
 628                         continue;
 629                 }
 630
 631                 LASSERT(page->cp_obj != NULL);
 632                 if (clobj != page->cp_obj) {
 633                         struct cl_object *tmp = page->cp_obj;
 634
 635                         cl_object_get(tmp);
 636                         spin_unlock(&cli->cl_lru_list_lock);
 637
 638                         if (clobj != NULL) {
 639                                 discard_pagevec(env, io, pvec, index);
 640                                 index = 0;
 641
 642                                 cl_io_fini(env, io);
 643                                 cl_object_put(env, clobj);
 644                                 clobj = NULL;
 645                         }
 646
 647                         clobj = tmp;
 648                         io->ci_obj = clobj;
 649                         io->ci_ignore_layout = 1;
 650                         rc = cl_io_init(env, io, CIT_MISC, clobj);
 651
 652                         spin_lock(&cli->cl_lru_list_lock);
 653
 654                         if (rc != 0)
 655                                 break;
 656
 657                         ++maxscan;
 658                         continue;
 659                 }
 660
 661                 if (cl_page_own_try(env, io, page) == 0) {
 662                         if (!lru_page_busy(cli, page)) {
 663                                 /* remove it from lru list earlier to avoid
 664                                  * lock contention */
 665                                 __osc_lru_del(cli, opg);
 666                                 opg->ops_in_lru = 0; /* will be discarded */
 667
 668                                 cl_page_get(page);
 669                                 will_free = true;
 670                         } else {
 671                                 cl_page_disown(env, io, page);
 672                         }
 673                 }
 674
 675                 if (!will_free) {
 676                         list_move_tail(&opg->ops_lru, &cli->cl_lru_list);
 677                         continue;
 678                 }
 679
 680                 /* Don't discard and free the page with cl_lru_list held */
 681                 pvec[index++] = page;
 682                 if (unlikely(index == OTI_PVEC_SIZE)) {
 683                         spin_unlock(&cli->cl_lru_list_lock);
 684                         discard_pagevec(env, io, pvec, index);
 685                         index = 0;
 686
 687                         spin_lock(&cli->cl_lru_list_lock);
 688                 }
 689
 690                 if (++count >= target)
 691                         break;
 692         }
 693         spin_unlock(&cli->cl_lru_list_lock);
 694
 695         if (clobj != NULL) {
 696                 discard_pagevec(env, io, pvec, index);
 697
 698                 cl_io_fini(env, io);
 699                 cl_object_put(env, clobj);
 700         }
 701
 702         atomic_dec(&cli->cl_lru_shrinkers);
 703         if (count > 0) {
 704                 atomic_long_add(count, cli->cl_lru_left);
 705                 wake_up_all(&osc_lru_waitq);
 706         }
 707         RETURN(count > 0 ? count : rc);
 708 }
 709 EXPORT_SYMBOL(osc_lru_shrink);
 710
 711 /**
 712  * Reclaim LRU pages by an IO thread. The caller wants to reclaim at least
 713  * \@npages of LRU slots. For performance consideration, it's better to drop
 714  * LRU pages in batch. Therefore, the actual number is adjusted at least
 715  * max_pages_per_rpc.
 716  */
 717 static long osc_lru_reclaim(struct client_obd *cli, unsigned long npages)
 718 {
 719         struct lu_env *env;
 720         struct cl_client_cache *cache = cli->cl_cache;
 721         int max_scans;
 722         __u16 refcheck;
 723         long rc = 0;
 724         ENTRY;
 725
 726         LASSERT(cache != NULL);
 727
 728         env = cl_env_get(&refcheck);
 729         if (IS_ERR(env))
 730                 RETURN(rc);
 731
 732         npages = max_t(int, npages, cli->cl_max_pages_per_rpc);
 733         CDEBUG(D_CACHE, "%s: start to reclaim %ld pages from LRU\n",
 734                cli_name(cli), npages);
 735         rc = osc_lru_shrink(env, cli, npages, true);
 736         if (rc >= npages) {
 737                 CDEBUG(D_CACHE, "%s: reclaimed %ld/%ld pages from LRU\n",
 738                        cli_name(cli), rc, npages);
 739                 if (osc_cache_too_much(cli) > 0)
 740                         ptlrpcd_queue_work(cli->cl_lru_work);
 741                 GOTO(out, rc);
 742         } else if (rc > 0) {
 743                 npages -= rc;
 744         }
 745
 746         CDEBUG(D_CACHE, "%s: cli %p no free slots, pages: %ld/%ld, want: %ld\n",
 747                 cli_name(cli), cli, atomic_long_read(&cli->cl_lru_in_list),
 748                 atomic_long_read(&cli->cl_lru_busy), npages);
 749
 750         /* Reclaim LRU slots from other client_obd as it can't free enough
 751          * from its own. This should rarely happen. */
 752         spin_lock(&cache->ccc_lru_lock);
 753         LASSERT(!list_empty(&cache->ccc_lru));
 754
 755         cache->ccc_lru_shrinkers++;
 756         list_move_tail(&cli->cl_lru_osc, &cache->ccc_lru);
 757
 758         max_scans = atomic_read(&cache->ccc_users) - 2;
 759         while (--max_scans > 0 && !list_empty(&cache->ccc_lru)) {
 760                 cli = list_entry(cache->ccc_lru.next, struct client_obd,
 761                                  cl_lru_osc);
 762
 763                 CDEBUG(D_CACHE, "%s: cli %p LRU pages: %ld, busy: %ld.\n",
 764                         cli_name(cli), cli,
 765                         atomic_long_read(&cli->cl_lru_in_list),
 766                         atomic_long_read(&cli->cl_lru_busy));
 767
 768                 list_move_tail(&cli->cl_lru_osc, &cache->ccc_lru);
 769                 if (osc_cache_too_much(cli) > 0) {
 770                         spin_unlock(&cache->ccc_lru_lock);
 771
 772                         rc = osc_lru_shrink(env, cli, npages, true);
 773                         spin_lock(&cache->ccc_lru_lock);
 774                         if (rc >= npages)
 775                                 break;
 776                         if (rc > 0)
 777                                 npages -= rc;
 778                 }
 779         }
 780         spin_unlock(&cache->ccc_lru_lock);
 781
 782 out:
 783         cl_env_put(env, &refcheck);
 784         CDEBUG(D_CACHE, "%s: cli %p freed %ld pages.\n",
 785                 cli_name(cli), cli, rc);
 786         return rc;
 787 }
 788
 789 /**
 790  * osc_lru_alloc() is called to allocate an LRU slot for a cl_page.
 791  *
 792  * Usually the LRU slots are reserved in osc_io_iter_rw_init().
 793  * Only in the case that the LRU slots are in extreme shortage, it should
 794  * have reserved enough slots for an IO.
 795  */
 796 static int osc_lru_alloc(const struct lu_env *env, struct client_obd *cli,
 797                          struct osc_page *opg)
 798 {
 799         struct l_wait_info lwi = LWI_INTR(LWI_ON_SIGNAL_NOOP, NULL);
 800         struct osc_io *oio = osc_env_io(env);
 801         int rc = 0;
 802
 803         ENTRY;
 804
 805         if (cli->cl_cache == NULL) /* shall not be in LRU */
 806                 RETURN(0);
 807
 808         if (oio->oi_lru_reserved > 0) {
 809                 --oio->oi_lru_reserved;
 810                 goto out;
 811         }
 812
 813         LASSERT(atomic_long_read(cli->cl_lru_left) >= 0);
 814         while (!atomic_long_add_unless(cli->cl_lru_left, -1, 0)) {
 815                 /* run out of LRU spaces, try to drop some by itself */
 816                 rc = osc_lru_reclaim(cli, 1);
 817                 if (rc < 0)
 818                         break;
 819                 if (rc > 0)
 820                         continue;
 821
 822                 cond_resched();
 823                 rc = l_wait_event(osc_lru_waitq,
 824                                 atomic_long_read(cli->cl_lru_left) > 0,
 825                                 &lwi);
 826                 if (rc < 0)
 827                         break;
 828         }
 829
 830 out:
 831         if (rc >= 0) {
 832                 atomic_long_inc(&cli->cl_lru_busy);
 833                 opg->ops_in_lru = 1;
 834                 rc = 0;
 835         }
 836
 837         RETURN(rc);
 838 }
 839
 840 /**
 841  * osc_lru_reserve() is called to reserve enough LRU slots for I/O.
 842  *
 843  * The benefit of doing this is to reduce contention against atomic counter
 844  * cl_lru_left by changing it from per-page access to per-IO access.
 845  */
 846 unsigned long osc_lru_reserve(struct client_obd *cli, unsigned long npages)
 847 {
 848         unsigned long reserved = 0;
 849         unsigned long max_pages;
 850         unsigned long c;
 851
 852         /* reserve a full RPC window at most to avoid that a thread accidentally
 853          * consumes too many LRU slots */
 854         max_pages = cli->cl_max_pages_per_rpc * cli->cl_max_rpcs_in_flight;
 855         if (npages > max_pages)
 856                 npages = max_pages;
 857
 858         c = atomic_long_read(cli->cl_lru_left);
 859         if (c < npages && osc_lru_reclaim(cli, npages) > 0)
 860                 c = atomic_long_read(cli->cl_lru_left);
 861         while (c >= npages) {
 862                 if (c == atomic_long_cmpxchg(cli->cl_lru_left, c, c - npages)) {
 863                         reserved = npages;
 864                         break;
 865                 }
 866                 c = atomic_long_read(cli->cl_lru_left);
 867         }
 868         if (atomic_long_read(cli->cl_lru_left) < max_pages) {
 869                 /* If there aren't enough pages in the per-OSC LRU then
 870                  * wake up the LRU thread to try and clear out space, so
 871                  * we don't block if pages are being dirtied quickly. */
 872                 CDEBUG(D_CACHE, "%s: queue LRU, left: %lu/%ld.\n",
 873                        cli_name(cli), atomic_long_read(cli->cl_lru_left),
 874                        max_pages);
 875                 (void)ptlrpcd_queue_work(cli->cl_lru_work);
 876         }
 877
 878         return reserved;
 879 }
 880
 881 /**
 882  * osc_lru_unreserve() is called to unreserve LRU slots.
 883  *
 884  * LRU slots reserved by osc_lru_reserve() may have entries left due to several
 885  * reasons such as page already existing or I/O error. Those reserved slots
 886  * should be freed by calling this function.
 887  */
 888 void osc_lru_unreserve(struct client_obd *cli, unsigned long npages)
 889 {
 890         atomic_long_add(npages, cli->cl_lru_left);
 891         wake_up_all(&osc_lru_waitq);
 892 }
 893
 894 /**
 895  * Atomic operations are expensive. We accumulate the accounting for the
 896  * same page zone to get better performance.
 897  * In practice this can work pretty good because the pages in the same RPC
 898  * are likely from the same page zone.
 899  */
 900 static inline void unstable_page_accounting(struct ptlrpc_bulk_desc *desc,
 901                                             struct osc_brw_async_args *aa,
 902                                             int factor)
 903 {
 904         int page_count;
 905         void *zone = NULL;
 906         int count = 0;
 907         int i;
 908
 909         if (desc != NULL) {
 910                 LASSERT(ptlrpc_is_bulk_desc_kiov(desc->bd_type));
 911                 page_count = desc->bd_iov_count;
 912         } else {
 913                 page_count = aa->aa_page_count;
 914         }
 915
 916         for (i = 0; i < page_count; i++) {
 917                 void *pz;
 918                 if (desc)
 919                         pz = page_zone(BD_GET_KIOV(desc, i).kiov_page);
 920                 else
 921                         pz = page_zone(aa->aa_ppga[i]->pg);
 922
 923                 if (likely(pz == zone)) {
 924                         ++count;
 925                         continue;
 926                 }
 927
 928                 if (count > 0) {
 929                         mod_zone_page_state(zone, NR_UNSTABLE_NFS,
 930                                             factor * count);
 931                         count = 0;
 932                 }
 933                 zone = pz;
 934                 ++count;
 935         }
 936         if (count > 0)
 937                 mod_zone_page_state(zone, NR_UNSTABLE_NFS, factor * count);
 938 }
 939
 940 static inline void add_unstable_page_accounting(struct ptlrpc_bulk_desc *desc,
 941                                                 struct osc_brw_async_args *aa)
 942 {
 943         unstable_page_accounting(desc, aa, 1);
 944 }
 945
 946 static inline void dec_unstable_page_accounting(struct ptlrpc_bulk_desc *desc,
 947                                                 struct osc_brw_async_args *aa)
 948 {
 949         unstable_page_accounting(desc, aa, -1);
 950 }
 951
 952 /**
 953  * Performs "unstable" page accounting. This function balances the
 954  * increment operations performed in osc_inc_unstable_pages. It is
 955  * registered as the RPC request callback, and is executed when the
 956  * bulk RPC is committed on the server. Thus at this point, the pages
 957  * involved in the bulk transfer are no longer considered unstable.
 958  *
 959  * If this function is called, the request should have been committed
 960  * or req:rq_unstable must have been set; it implies that the unstable
 961  * statistic have been added.
 962  */
 963 void osc_dec_unstable_pages(struct ptlrpc_request *req)
 964 {
 965         struct ptlrpc_bulk_desc *desc       = req->rq_bulk;
 966         struct osc_brw_async_args *aa = (void *)&req->rq_async_args;
 967         struct client_obd       *cli        = &req->rq_import->imp_obd->u.cli;
 968         int                      page_count;
 969         long                     unstable_count;
 970
 971         if (desc)
 972                 page_count = desc->bd_iov_count;
 973         else
 974                 page_count = aa->aa_page_count;
 975
 976         LASSERT(page_count >= 0);
 977
 978         dec_unstable_page_accounting(desc, aa);
 979
 980         unstable_count = atomic_long_sub_return(page_count,
 981                                                 &cli->cl_unstable_count);
 982         LASSERT(unstable_count >= 0);
 983
 984         unstable_count = atomic_long_sub_return(page_count,
 985                                            &cli->cl_cache->ccc_unstable_nr);
 986         LASSERT(unstable_count >= 0);
 987         if (unstable_count == 0)
 988                 wake_up_all(&cli->cl_cache->ccc_unstable_waitq);
 989
 990         if (waitqueue_active(&osc_lru_waitq))
 991                 (void)ptlrpcd_queue_work(cli->cl_lru_work);
 992 }
 993
 994 /**
 995  * "unstable" page accounting. See: osc_dec_unstable_pages.
 996  */
 997 void osc_inc_unstable_pages(struct ptlrpc_request *req)
 998 {
 999         struct ptlrpc_bulk_desc *desc = req->rq_bulk;
1000         struct osc_brw_async_args *aa = (void *)&req->rq_async_args;
1001         struct client_obd       *cli  = &req->rq_import->imp_obd->u.cli;
1002         long                     page_count;
1003
1004         /* No unstable page tracking */
1005         if (cli->cl_cache == NULL || !cli->cl_cache->ccc_unstable_check)
1006                 return;
1007
1008         if (desc)
1009                 page_count = desc->bd_iov_count;
1010         else
1011                 page_count = aa->aa_page_count;
1012
1013         add_unstable_page_accounting(desc, aa);
1014         atomic_long_add(page_count, &cli->cl_unstable_count);
1015         atomic_long_add(page_count, &cli->cl_cache->ccc_unstable_nr);
1016
1017         /* If the request has already been committed (i.e. brw_commit
1018          * called via rq_commit_cb), we need to undo the unstable page
1019          * increments we just performed because rq_commit_cb wont be
1020          * called again. */
1021         spin_lock(&req->rq_lock);
1022         if (unlikely(req->rq_committed)) {
1023                 spin_unlock(&req->rq_lock);
1024
1025                 osc_dec_unstable_pages(req);
1026         } else {
1027                 req->rq_unstable = 1;
1028                 spin_unlock(&req->rq_lock);
1029         }
1030 }
1031
1032 /**
1033  * Check if it piggybacks SOFT_SYNC flag to OST from this OSC.
1034  * This function will be called by every BRW RPC so it's critical
1035  * to make this function fast.
1036  */
1037 bool osc_over_unstable_soft_limit(struct client_obd *cli)
1038 {
1039         long unstable_nr, osc_unstable_count;
1040
1041         /* Can't check cli->cl_unstable_count, therefore, no soft limit */
1042         if (cli->cl_cache == NULL || !cli->cl_cache->ccc_unstable_check)
1043                 return false;
1044
1045         osc_unstable_count = atomic_long_read(&cli->cl_unstable_count);
1046         unstable_nr = atomic_long_read(&cli->cl_cache->ccc_unstable_nr);
1047
1048         CDEBUG(D_CACHE,
1049                "%s: cli: %p unstable pages: %lu, osc unstable pages: %lu\n",
1050                cli_name(cli), cli, unstable_nr, osc_unstable_count);
1051
1052         /* If the LRU slots are in shortage - 25% remaining AND this OSC
1053          * has one full RPC window of unstable pages, it's a good chance
1054          * to piggyback a SOFT_SYNC flag.
1055          * Please notice that the OST won't take immediate response for the
1056          * SOFT_SYNC request so active OSCs will have more chance to carry
1057          * the flag, this is reasonable. */
1058         return unstable_nr > cli->cl_cache->ccc_lru_max >> 2 &&
1059                osc_unstable_count > cli->cl_max_pages_per_rpc *
1060                                     cli->cl_max_rpcs_in_flight;
1061 }
1062
1063 /**
1064  * Return how many LRU pages in the cache of all OSC devices
1065  *
1066  * \retval      return # of cached LRU pages times reclaimation tendency
1067  * \retval      SHRINK_STOP if it cannot do any scanning in this time
1068  */
1069 unsigned long osc_cache_shrink_count(struct shrinker *sk,
1070                                      struct shrink_control *sc)
1071 {
1072         struct client_obd *cli;
1073         unsigned long cached = 0;
1074
1075         spin_lock(&osc_shrink_lock);
1076         list_for_each_entry(cli, &osc_shrink_list, cl_shrink_list)
1077                 cached += atomic_long_read(&cli->cl_lru_in_list);
1078         spin_unlock(&osc_shrink_lock);
1079
1080         return (cached  * sysctl_vfs_cache_pressure) / 100;
1081 }
1082
1083 /**
1084  * Scan and try to reclaim sc->nr_to_scan cached LRU pages
1085  *
1086  * \retval      number of cached LRU pages reclaimed
1087  * \retval      SHRINK_STOP if it cannot do any scanning in this time
1088  *
1089  * Linux kernel will loop calling this shrinker scan routine with
1090  * sc->nr_to_scan = SHRINK_BATCH(128 for now) until kernel got enough memory.
1091  *
1092  * If sc->nr_to_scan is 0, the VM is querying the cache size, we don't need
1093  * to scan and try to reclaim LRU pages, just return 0 and
1094  * osc_cache_shrink_count() will report the LRU page number.
1095  */
1096 unsigned long osc_cache_shrink_scan(struct shrinker *sk,
1097                                     struct shrink_control *sc)
1098 {
1099         struct client_obd *cli;
1100         struct client_obd *stop_anchor = NULL;
1101         struct lu_env *env;
1102         long shrank = 0;
1103         int rc;
1104         __u16 refcheck;
1105
1106         if (sc->nr_to_scan == 0)
1107                 return 0;
1108
1109         if (!(sc->gfp_mask & __GFP_FS))
1110                 return SHRINK_STOP;
1111
1112         env = cl_env_get(&refcheck);
1113         if (IS_ERR(env))
1114                 return SHRINK_STOP;
1115
1116         spin_lock(&osc_shrink_lock);
1117         while (!list_empty(&osc_shrink_list)) {
1118                 cli = list_entry(osc_shrink_list.next, struct client_obd,
1119                                  cl_shrink_list);
1120
1121                 if (stop_anchor == NULL)
1122                         stop_anchor = cli;
1123                 else if (cli == stop_anchor)
1124                         break;
1125
1126                 list_move_tail(&cli->cl_shrink_list, &osc_shrink_list);
1127                 spin_unlock(&osc_shrink_lock);
1128
1129                 /* shrink no more than max_pages_per_rpc for an OSC */
1130                 rc = osc_lru_shrink(env, cli, (sc->nr_to_scan - shrank) >
1131                                     cli->cl_max_pages_per_rpc ?
1132                                     cli->cl_max_pages_per_rpc :
1133                                     sc->nr_to_scan - shrank, true);
1134                 if (rc > 0)
1135                         shrank += rc;
1136
1137                 if (shrank >= sc->nr_to_scan)
1138                         goto out;
1139
1140                 spin_lock(&osc_shrink_lock);
1141         }
1142         spin_unlock(&osc_shrink_lock);
1143
1144 out:
1145         cl_env_put(env, &refcheck);
1146
1147         return shrank;
1148 }
1149
1150 /** @} osc */