drivers/staging/lustre/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, 2015, 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
  40 #include "osc_cl_internal.h"
  41
  42 static void osc_lru_del(struct client_obd *cli, struct osc_page *opg);
  43 static void osc_lru_use(struct client_obd *cli, struct osc_page *opg);
  44 static int osc_lru_reserve(const struct lu_env *env, struct osc_object *obj,
  45                            struct osc_page *opg);
  46
  47 /** \addtogroup osc
  48  *  @{
  49  */
  50
  51 /*****************************************************************************
  52  *
  53  * Page operations.
  54  *
  55  */
  56 static void osc_page_transfer_get(struct osc_page *opg, const char *label)
  57 {
  58         struct cl_page *page = opg->ops_cl.cpl_page;
  59
  60         LASSERT(!opg->ops_transfer_pinned);
  61         cl_page_get(page);
  62         lu_ref_add_atomic(&page->cp_reference, label, page);
  63         opg->ops_transfer_pinned = 1;
  64 }
  65
  66 static void osc_page_transfer_put(const struct lu_env *env,
  67                                   struct osc_page *opg)
  68 {
  69         struct cl_page *page = opg->ops_cl.cpl_page;
  70
  71         if (opg->ops_transfer_pinned) {
  72                 opg->ops_transfer_pinned = 0;
  73                 lu_ref_del(&page->cp_reference, "transfer", page);
  74                 cl_page_put(env, page);
  75         }
  76 }
  77
  78 /**
  79  * This is called once for every page when it is submitted for a transfer
  80  * either opportunistic (osc_page_cache_add()), or immediate
  81  * (osc_page_submit()).
  82  */
  83 static void osc_page_transfer_add(const struct lu_env *env,
  84                                   struct osc_page *opg, enum cl_req_type crt)
  85 {
  86         struct osc_object *obj = cl2osc(opg->ops_cl.cpl_obj);
  87
  88         osc_lru_use(osc_cli(obj), opg);
  89
  90         spin_lock(&obj->oo_seatbelt);
  91         list_add(&opg->ops_inflight, &obj->oo_inflight[crt]);
  92         opg->ops_submitter = current;
  93         spin_unlock(&obj->oo_seatbelt);
  94 }
  95
  96 int osc_page_cache_add(const struct lu_env *env,
  97                        const struct cl_page_slice *slice, struct cl_io *io)
  98 {
  99         struct osc_page *opg = cl2osc_page(slice);
 100         int result;
 101
 102         osc_page_transfer_get(opg, "transfer\0cache");
 103         result = osc_queue_async_io(env, io, opg);
 104         if (result != 0)
 105                 osc_page_transfer_put(env, opg);
 106         else
 107                 osc_page_transfer_add(env, opg, CRT_WRITE);
 108
 109         return result;
 110 }
 111
 112 void osc_index2policy(ldlm_policy_data_t *policy, const struct cl_object *obj,
 113                       pgoff_t start, pgoff_t end)
 114 {
 115         memset(policy, 0, sizeof(*policy));
 116         policy->l_extent.start = cl_offset(obj, start);
 117         policy->l_extent.end = cl_offset(obj, end + 1) - 1;
 118 }
 119
 120 static int osc_page_is_under_lock(const struct lu_env *env,
 121                                   const struct cl_page_slice *slice,
 122                                   struct cl_io *unused, pgoff_t *max_index)
 123 {
 124         struct osc_page *opg = cl2osc_page(slice);
 125         struct ldlm_lock *dlmlock;
 126         int result = -ENODATA;
 127
 128         dlmlock = osc_dlmlock_at_pgoff(env, cl2osc(slice->cpl_obj),
 129                                        osc_index(opg), 1, 0);
 130         if (dlmlock) {
 131                 *max_index = cl_index(slice->cpl_obj,
 132                                       dlmlock->l_policy_data.l_extent.end);
 133                 LDLM_LOCK_PUT(dlmlock);
 134                 result = 0;
 135         }
 136         return result;
 137 }
 138
 139 static const char *osc_list(struct list_head *head)
 140 {
 141         return list_empty(head) ? "-" : "+";
 142 }
 143
 144 static inline unsigned long osc_submit_duration(struct osc_page *opg)
 145 {
 146         if (opg->ops_submit_time == 0)
 147                 return 0;
 148
 149         return (cfs_time_current() - opg->ops_submit_time);
 150 }
 151
 152 static int osc_page_print(const struct lu_env *env,
 153                           const struct cl_page_slice *slice,
 154                           void *cookie, lu_printer_t printer)
 155 {
 156         struct osc_page *opg = cl2osc_page(slice);
 157         struct osc_async_page *oap = &opg->ops_oap;
 158         struct osc_object *obj = cl2osc(slice->cpl_obj);
 159         struct client_obd *cli = &osc_export(obj)->exp_obd->u.cli;
 160
 161         return (*printer)(env, cookie, LUSTRE_OSC_NAME "-page@%p %lu: 1< %#x %d %u %s %s > 2< %llu %u %u %#x %#x | %p %p %p > 3< %s %p %d %lu %d > 4< %d %d %d %lu %s | %s %s %s %s > 5< %s %s %s %s | %d %s | %d %s %s>\n",
 162                           opg, osc_index(opg),
 163                           /* 1 */
 164                           oap->oap_magic, oap->oap_cmd,
 165                           oap->oap_interrupted,
 166                           osc_list(&oap->oap_pending_item),
 167                           osc_list(&oap->oap_rpc_item),
 168                           /* 2 */
 169                           oap->oap_obj_off, oap->oap_page_off, oap->oap_count,
 170                           oap->oap_async_flags, oap->oap_brw_flags,
 171                           oap->oap_request, oap->oap_cli, obj,
 172                           /* 3 */
 173                           osc_list(&opg->ops_inflight),
 174                           opg->ops_submitter, opg->ops_transfer_pinned,
 175                           osc_submit_duration(opg), opg->ops_srvlock,
 176                           /* 4 */
 177                           cli->cl_r_in_flight, cli->cl_w_in_flight,
 178                           cli->cl_max_rpcs_in_flight,
 179                           cli->cl_avail_grant,
 180                           osc_list(&cli->cl_cache_waiters),
 181                           osc_list(&cli->cl_loi_ready_list),
 182                           osc_list(&cli->cl_loi_hp_ready_list),
 183                           osc_list(&cli->cl_loi_write_list),
 184                           osc_list(&cli->cl_loi_read_list),
 185                           /* 5 */
 186                           osc_list(&obj->oo_ready_item),
 187                           osc_list(&obj->oo_hp_ready_item),
 188                           osc_list(&obj->oo_write_item),
 189                           osc_list(&obj->oo_read_item),
 190                           atomic_read(&obj->oo_nr_reads),
 191                           osc_list(&obj->oo_reading_exts),
 192                           atomic_read(&obj->oo_nr_writes),
 193                           osc_list(&obj->oo_hp_exts),
 194                           osc_list(&obj->oo_urgent_exts));
 195 }
 196
 197 static void osc_page_delete(const struct lu_env *env,
 198                             const struct cl_page_slice *slice)
 199 {
 200         struct osc_page *opg = cl2osc_page(slice);
 201         struct osc_object *obj = cl2osc(opg->ops_cl.cpl_obj);
 202         int rc;
 203
 204         CDEBUG(D_TRACE, "%p\n", opg);
 205         osc_page_transfer_put(env, opg);
 206         rc = osc_teardown_async_page(env, obj, opg);
 207         if (rc) {
 208                 CL_PAGE_DEBUG(D_ERROR, env, slice->cpl_page,
 209                               "Trying to teardown failed: %d\n", rc);
 210                 LASSERT(0);
 211         }
 212
 213         spin_lock(&obj->oo_seatbelt);
 214         if (opg->ops_submitter) {
 215                 LASSERT(!list_empty(&opg->ops_inflight));
 216                 list_del_init(&opg->ops_inflight);
 217                 opg->ops_submitter = NULL;
 218         }
 219         spin_unlock(&obj->oo_seatbelt);
 220
 221         osc_lru_del(osc_cli(obj), opg);
 222
 223         if (slice->cpl_page->cp_type == CPT_CACHEABLE) {
 224                 void *value;
 225
 226                 spin_lock(&obj->oo_tree_lock);
 227                 value = radix_tree_delete(&obj->oo_tree, osc_index(opg));
 228                 if (value)
 229                         --obj->oo_npages;
 230                 spin_unlock(&obj->oo_tree_lock);
 231
 232                 LASSERT(ergo(value, value == opg));
 233         }
 234 }
 235
 236 static void osc_page_clip(const struct lu_env *env,
 237                           const struct cl_page_slice *slice, int from, int to)
 238 {
 239         struct osc_page *opg = cl2osc_page(slice);
 240         struct osc_async_page *oap = &opg->ops_oap;
 241
 242         opg->ops_from = from;
 243         opg->ops_to = to;
 244         spin_lock(&oap->oap_lock);
 245         oap->oap_async_flags |= ASYNC_COUNT_STABLE;
 246         spin_unlock(&oap->oap_lock);
 247 }
 248
 249 static int osc_page_cancel(const struct lu_env *env,
 250                            const struct cl_page_slice *slice)
 251 {
 252         struct osc_page *opg = cl2osc_page(slice);
 253         int rc = 0;
 254
 255         /* Check if the transferring against this page
 256          * is completed, or not even queued.
 257          */
 258         if (opg->ops_transfer_pinned)
 259                 /* FIXME: may not be interrupted.. */
 260                 rc = osc_cancel_async_page(env, opg);
 261         LASSERT(ergo(rc == 0, opg->ops_transfer_pinned == 0));
 262         return rc;
 263 }
 264
 265 static int osc_page_flush(const struct lu_env *env,
 266                           const struct cl_page_slice *slice,
 267                           struct cl_io *io)
 268 {
 269         struct osc_page *opg = cl2osc_page(slice);
 270         int rc;
 271
 272         rc = osc_flush_async_page(env, io, opg);
 273         return rc;
 274 }
 275
 276 static const struct cl_page_operations osc_page_ops = {
 277         .cpo_print       = osc_page_print,
 278         .cpo_delete     = osc_page_delete,
 279         .cpo_is_under_lock = osc_page_is_under_lock,
 280         .cpo_clip          = osc_page_clip,
 281         .cpo_cancel      = osc_page_cancel,
 282         .cpo_flush        = osc_page_flush
 283 };
 284
 285 int osc_page_init(const struct lu_env *env, struct cl_object *obj,
 286                   struct cl_page *page, pgoff_t index)
 287 {
 288         struct osc_object *osc = cl2osc(obj);
 289         struct osc_page *opg = cl_object_page_slice(obj, page);
 290         int result;
 291
 292         opg->ops_from = 0;
 293         opg->ops_to = PAGE_SIZE;
 294
 295         result = osc_prep_async_page(osc, opg, page->cp_vmpage,
 296                                      cl_offset(obj, index));
 297         if (result == 0) {
 298                 struct osc_io *oio = osc_env_io(env);
 299
 300                 opg->ops_srvlock = osc_io_srvlock(oio);
 301                 cl_page_slice_add(page, &opg->ops_cl, obj, index,
 302                                   &osc_page_ops);
 303         }
 304         /* ops_inflight and ops_lru are the same field, but it doesn't
 305          * hurt to initialize it twice :-)
 306          */
 307         INIT_LIST_HEAD(&opg->ops_inflight);
 308         INIT_LIST_HEAD(&opg->ops_lru);
 309
 310         /* reserve an LRU space for this page */
 311         if (page->cp_type == CPT_CACHEABLE && result == 0) {
 312                 result = osc_lru_reserve(env, osc, opg);
 313                 if (result == 0) {
 314                         spin_lock(&osc->oo_tree_lock);
 315                         result = radix_tree_insert(&osc->oo_tree, index, opg);
 316                         if (result == 0)
 317                                 ++osc->oo_npages;
 318                         spin_unlock(&osc->oo_tree_lock);
 319                         LASSERT(result == 0);
 320                 }
 321         }
 322
 323         return result;
 324 }
 325
 326 /**
 327  * Helper function called by osc_io_submit() for every page in an immediate
 328  * transfer (i.e., transferred synchronously).
 329  */
 330 void osc_page_submit(const struct lu_env *env, struct osc_page *opg,
 331                      enum cl_req_type crt, int brw_flags)
 332 {
 333         struct osc_async_page *oap = &opg->ops_oap;
 334
 335         LASSERTF(oap->oap_magic == OAP_MAGIC, "Bad oap magic: oap %p, magic 0x%x\n",
 336                  oap, oap->oap_magic);
 337         LASSERT(oap->oap_async_flags & ASYNC_READY);
 338         LASSERT(oap->oap_async_flags & ASYNC_COUNT_STABLE);
 339
 340         oap->oap_cmd = crt == CRT_WRITE ? OBD_BRW_WRITE : OBD_BRW_READ;
 341         oap->oap_page_off = opg->ops_from;
 342         oap->oap_count = opg->ops_to - opg->ops_from;
 343         oap->oap_brw_flags = brw_flags | OBD_BRW_SYNC;
 344
 345         if (capable(CFS_CAP_SYS_RESOURCE)) {
 346                 oap->oap_brw_flags |= OBD_BRW_NOQUOTA;
 347                 oap->oap_cmd |= OBD_BRW_NOQUOTA;
 348         }
 349
 350         opg->ops_submit_time = cfs_time_current();
 351         osc_page_transfer_get(opg, "transfer\0imm");
 352         osc_page_transfer_add(env, opg, crt);
 353 }
 354
 355 /* --------------- LRU page management ------------------ */
 356
 357 /* OSC is a natural place to manage LRU pages as applications are specialized
 358  * to write OSC by OSC. Ideally, if one OSC is used more frequently it should
 359  * occupy more LRU slots. On the other hand, we should avoid using up all LRU
 360  * slots (client_obd::cl_lru_left) otherwise process has to be put into sleep
 361  * for free LRU slots - this will be very bad so the algorithm requires each
 362  * OSC to free slots voluntarily to maintain a reasonable number of free slots
 363  * at any time.
 364  */
 365
 366 static DECLARE_WAIT_QUEUE_HEAD(osc_lru_waitq);
 367 /* LRU pages are freed in batch mode. OSC should at least free this
 368  * number of pages to avoid running out of LRU budget, and..
 369  */
 370 static const int lru_shrink_min = 2 << (20 - PAGE_SHIFT);  /* 2M */
 371 /* free this number at most otherwise it will take too long time to finish. */
 372 static const int lru_shrink_max = 8 << (20 - PAGE_SHIFT); /* 8M */
 373
 374 /* Check if we can free LRU slots from this OSC. If there exists LRU waiters,
 375  * we should free slots aggressively. In this way, slots are freed in a steady
 376  * step to maintain fairness among OSCs.
 377  *
 378  * Return how many LRU pages should be freed.
 379  */
 380 static int osc_cache_too_much(struct client_obd *cli)
 381 {
 382         struct cl_client_cache *cache = cli->cl_cache;
 383         long pages = atomic_long_read(&cli->cl_lru_in_list);
 384         unsigned long budget;
 385
 386         budget = cache->ccc_lru_max / (atomic_read(&cache->ccc_users) - 2);
 387
 388         /* if it's going to run out LRU slots, we should free some, but not
 389          * too much to maintain fairness among OSCs.
 390          */
 391         if (atomic_long_read(cli->cl_lru_left) < cache->ccc_lru_max >> 4) {
 392                 if (pages >= budget)
 393                         return lru_shrink_max;
 394                 else if (pages >= budget / 2)
 395                         return lru_shrink_min;
 396         } else if (pages >= budget * 2) {
 397                 return lru_shrink_min;
 398         }
 399         return 0;
 400 }
 401
 402 int lru_queue_work(const struct lu_env *env, void *data)
 403 {
 404         struct client_obd *cli = data;
 405
 406         CDEBUG(D_CACHE, "Run LRU work for client obd %p.\n", cli);
 407
 408         if (osc_cache_too_much(cli))
 409                 osc_lru_shrink(env, cli, lru_shrink_max, true);
 410
 411         return 0;
 412 }
 413
 414 void osc_lru_add_batch(struct client_obd *cli, struct list_head *plist)
 415 {
 416         LIST_HEAD(lru);
 417         struct osc_async_page *oap;
 418         long npages = 0;
 419
 420         list_for_each_entry(oap, plist, oap_pending_item) {
 421                 struct osc_page *opg = oap2osc_page(oap);
 422
 423                 if (!opg->ops_in_lru)
 424                         continue;
 425
 426                 ++npages;
 427                 LASSERT(list_empty(&opg->ops_lru));
 428                 list_add(&opg->ops_lru, &lru);
 429         }
 430
 431         if (npages > 0) {
 432                 spin_lock(&cli->cl_lru_list_lock);
 433                 list_splice_tail(&lru, &cli->cl_lru_list);
 434                 atomic_long_sub(npages, &cli->cl_lru_busy);
 435                 atomic_long_add(npages, &cli->cl_lru_in_list);
 436                 spin_unlock(&cli->cl_lru_list_lock);
 437
 438                 /* XXX: May set force to be true for better performance */
 439                 if (osc_cache_too_much(cli))
 440                         (void)ptlrpcd_queue_work(cli->cl_lru_work);
 441         }
 442 }
 443
 444 static void __osc_lru_del(struct client_obd *cli, struct osc_page *opg)
 445 {
 446         LASSERT(atomic_long_read(&cli->cl_lru_in_list) > 0);
 447         list_del_init(&opg->ops_lru);
 448         atomic_long_dec(&cli->cl_lru_in_list);
 449 }
 450
 451 /**
 452  * Page is being destroyed. The page may be not in LRU list, if the transfer
 453  * has never finished(error occurred).
 454  */
 455 static void osc_lru_del(struct client_obd *cli, struct osc_page *opg)
 456 {
 457         if (opg->ops_in_lru) {
 458                 spin_lock(&cli->cl_lru_list_lock);
 459                 if (!list_empty(&opg->ops_lru)) {
 460                         __osc_lru_del(cli, opg);
 461                 } else {
 462                         LASSERT(atomic_long_read(&cli->cl_lru_busy) > 0);
 463                         atomic_long_dec(&cli->cl_lru_busy);
 464                 }
 465                 spin_unlock(&cli->cl_lru_list_lock);
 466
 467                 atomic_long_inc(cli->cl_lru_left);
 468                 /* this is a great place to release more LRU pages if
 469                  * this osc occupies too many LRU pages and kernel is
 470                  * stealing one of them.
 471                  */
 472                 if (!memory_pressure_get())
 473                         (void)ptlrpcd_queue_work(cli->cl_lru_work);
 474                 wake_up(&osc_lru_waitq);
 475         } else {
 476                 LASSERT(list_empty(&opg->ops_lru));
 477         }
 478 }
 479
 480 /**
 481  * Delete page from LRUlist for redirty.
 482  */
 483 static void osc_lru_use(struct client_obd *cli, struct osc_page *opg)
 484 {
 485         /* If page is being transferred for the first time,
 486          * ops_lru should be empty
 487          */
 488         if (opg->ops_in_lru && !list_empty(&opg->ops_lru)) {
 489                 spin_lock(&cli->cl_lru_list_lock);
 490                 __osc_lru_del(cli, opg);
 491                 spin_unlock(&cli->cl_lru_list_lock);
 492                 atomic_long_inc(&cli->cl_lru_busy);
 493         }
 494 }
 495
 496 static void discard_pagevec(const struct lu_env *env, struct cl_io *io,
 497                             struct cl_page **pvec, int max_index)
 498 {
 499         int i;
 500
 501         for (i = 0; i < max_index; i++) {
 502                 struct cl_page *page = pvec[i];
 503
 504                 LASSERT(cl_page_is_owned(page, io));
 505                 cl_page_discard(env, io, page);
 506                 cl_page_disown(env, io, page);
 507                 cl_page_put(env, page);
 508
 509                 pvec[i] = NULL;
 510         }
 511 }
 512
 513 /**
 514  * Check if a cl_page can be released, i.e, it's not being used.
 515  *
 516  * If unstable account is turned on, bulk transfer may hold one refcount
 517  * for recovery so we need to check vmpage refcount as well; otherwise,
 518  * even we can destroy cl_page but the corresponding vmpage can't be reused.
 519  */
 520 static inline bool lru_page_busy(struct client_obd *cli, struct cl_page *page)
 521 {
 522         if (cl_page_in_use_noref(page))
 523                 return true;
 524
 525         if (cli->cl_cache->ccc_unstable_check) {
 526                 struct page *vmpage = cl_page_vmpage(page);
 527
 528                 /* vmpage have two known users: cl_page and VM page cache */
 529                 if (page_count(vmpage) - page_mapcount(vmpage) > 2)
 530                         return true;
 531         }
 532         return false;
 533 }
 534
 535 /**
 536  * Drop @target of pages from LRU at most.
 537  */
 538 long osc_lru_shrink(const struct lu_env *env, struct client_obd *cli,
 539                     long target, bool force)
 540 {
 541         struct cl_io *io;
 542         struct cl_object *clobj = NULL;
 543         struct cl_page **pvec;
 544         struct osc_page *opg;
 545         int maxscan = 0;
 546         long count = 0;
 547         int index = 0;
 548         int rc = 0;
 549
 550         LASSERT(atomic_long_read(&cli->cl_lru_in_list) >= 0);
 551         if (atomic_long_read(&cli->cl_lru_in_list) == 0 || target <= 0)
 552                 return 0;
 553
 554         if (!force) {
 555                 if (atomic_read(&cli->cl_lru_shrinkers) > 0)
 556                         return -EBUSY;
 557
 558                 if (atomic_inc_return(&cli->cl_lru_shrinkers) > 1) {
 559                         atomic_dec(&cli->cl_lru_shrinkers);
 560                         return -EBUSY;
 561                 }
 562         } else {
 563                 atomic_inc(&cli->cl_lru_shrinkers);
 564         }
 565
 566         pvec = (struct cl_page **)osc_env_info(env)->oti_pvec;
 567         io = &osc_env_info(env)->oti_io;
 568
 569         spin_lock(&cli->cl_lru_list_lock);
 570         maxscan = min(target << 1, atomic_long_read(&cli->cl_lru_in_list));
 571         while (!list_empty(&cli->cl_lru_list)) {
 572                 struct cl_page *page;
 573                 bool will_free = false;
 574
 575                 if (--maxscan < 0)
 576                         break;
 577
 578                 opg = list_entry(cli->cl_lru_list.next, struct osc_page,
 579                                  ops_lru);
 580                 page = opg->ops_cl.cpl_page;
 581                 if (lru_page_busy(cli, page)) {
 582                         list_move_tail(&opg->ops_lru, &cli->cl_lru_list);
 583                         continue;
 584                 }
 585
 586                 LASSERT(page->cp_obj);
 587                 if (clobj != page->cp_obj) {
 588                         struct cl_object *tmp = page->cp_obj;
 589
 590                         cl_object_get(tmp);
 591                         spin_unlock(&cli->cl_lru_list_lock);
 592
 593                         if (clobj) {
 594                                 discard_pagevec(env, io, pvec, index);
 595                                 index = 0;
 596
 597                                 cl_io_fini(env, io);
 598                                 cl_object_put(env, clobj);
 599                                 clobj = NULL;
 600                         }
 601
 602                         clobj = tmp;
 603                         io->ci_obj = clobj;
 604                         io->ci_ignore_layout = 1;
 605                         rc = cl_io_init(env, io, CIT_MISC, clobj);
 606
 607                         spin_lock(&cli->cl_lru_list_lock);
 608
 609                         if (rc != 0)
 610                                 break;
 611
 612                         ++maxscan;
 613                         continue;
 614                 }
 615
 616                 if (cl_page_own_try(env, io, page) == 0) {
 617                         if (!lru_page_busy(cli, page)) {
 618                                 /* remove it from lru list earlier to avoid
 619                                  * lock contention
 620                                  */
 621                                 __osc_lru_del(cli, opg);
 622                                 opg->ops_in_lru = 0; /* will be discarded */
 623
 624                                 cl_page_get(page);
 625                                 will_free = true;
 626                         } else {
 627                                 cl_page_disown(env, io, page);
 628                         }
 629                 }
 630
 631                 if (!will_free) {
 632                         list_move_tail(&opg->ops_lru, &cli->cl_lru_list);
 633                         continue;
 634                 }
 635
 636                 /* Don't discard and free the page with cl_lru_list held */
 637                 pvec[index++] = page;
 638                 if (unlikely(index == OTI_PVEC_SIZE)) {
 639                         spin_unlock(&cli->cl_lru_list_lock);
 640                         discard_pagevec(env, io, pvec, index);
 641                         index = 0;
 642
 643                         spin_lock(&cli->cl_lru_list_lock);
 644                 }
 645
 646                 if (++count >= target)
 647                         break;
 648         }
 649         spin_unlock(&cli->cl_lru_list_lock);
 650
 651         if (clobj) {
 652                 discard_pagevec(env, io, pvec, index);
 653
 654                 cl_io_fini(env, io);
 655                 cl_object_put(env, clobj);
 656         }
 657
 658         atomic_dec(&cli->cl_lru_shrinkers);
 659         if (count > 0) {
 660                 atomic_long_add(count, cli->cl_lru_left);
 661                 wake_up_all(&osc_lru_waitq);
 662         }
 663         return count > 0 ? count : rc;
 664 }
 665
 666 long osc_lru_reclaim(struct client_obd *cli)
 667 {
 668         struct cl_env_nest nest;
 669         struct lu_env *env;
 670         struct cl_client_cache *cache = cli->cl_cache;
 671         int max_scans;
 672         long rc = 0;
 673
 674         LASSERT(cache);
 675
 676         env = cl_env_nested_get(&nest);
 677         if (IS_ERR(env))
 678                 return 0;
 679
 680         rc = osc_lru_shrink(env, cli, osc_cache_too_much(cli), false);
 681         if (rc != 0) {
 682                 if (rc == -EBUSY)
 683                         rc = 0;
 684
 685                 CDEBUG(D_CACHE, "%s: Free %ld pages from own LRU: %p.\n",
 686                        cli->cl_import->imp_obd->obd_name, rc, cli);
 687                 goto out;
 688         }
 689
 690         CDEBUG(D_CACHE, "%s: cli %p no free slots, pages: %ld, busy: %ld.\n",
 691                cli->cl_import->imp_obd->obd_name, cli,
 692                atomic_long_read(&cli->cl_lru_in_list),
 693                atomic_long_read(&cli->cl_lru_busy));
 694
 695         /* Reclaim LRU slots from other client_obd as it can't free enough
 696          * from its own. This should rarely happen.
 697          */
 698         spin_lock(&cache->ccc_lru_lock);
 699         LASSERT(!list_empty(&cache->ccc_lru));
 700
 701         cache->ccc_lru_shrinkers++;
 702         list_move_tail(&cli->cl_lru_osc, &cache->ccc_lru);
 703
 704         max_scans = atomic_read(&cache->ccc_users) - 2;
 705         while (--max_scans > 0 && !list_empty(&cache->ccc_lru)) {
 706                 cli = list_entry(cache->ccc_lru.next, struct client_obd,
 707                                  cl_lru_osc);
 708
 709                 CDEBUG(D_CACHE, "%s: cli %p LRU pages: %ld, busy: %ld.\n",
 710                        cli->cl_import->imp_obd->obd_name, cli,
 711                        atomic_long_read(&cli->cl_lru_in_list),
 712                        atomic_long_read(&cli->cl_lru_busy));
 713
 714                 list_move_tail(&cli->cl_lru_osc, &cache->ccc_lru);
 715                 if (osc_cache_too_much(cli) > 0) {
 716                         spin_unlock(&cache->ccc_lru_lock);
 717
 718                         rc = osc_lru_shrink(env, cli, osc_cache_too_much(cli),
 719                                             true);
 720                         spin_lock(&cache->ccc_lru_lock);
 721                         if (rc != 0)
 722                                 break;
 723                 }
 724         }
 725         spin_unlock(&cache->ccc_lru_lock);
 726
 727 out:
 728         cl_env_nested_put(&nest, env);
 729         CDEBUG(D_CACHE, "%s: cli %p freed %ld pages.\n",
 730                cli->cl_import->imp_obd->obd_name, cli, rc);
 731         return rc;
 732 }
 733
 734 /**
 735  * osc_lru_reserve() is called to reserve an LRU slot for a cl_page.
 736  *
 737  * Usually the LRU slots are reserved in osc_io_iter_rw_init().
 738  * Only in the case that the LRU slots are in extreme shortage, it should
 739  * have reserved enough slots for an IO.
 740  */
 741 static int osc_lru_reserve(const struct lu_env *env, struct osc_object *obj,
 742                            struct osc_page *opg)
 743 {
 744         struct l_wait_info lwi = LWI_INTR(LWI_ON_SIGNAL_NOOP, NULL);
 745         struct osc_io *oio = osc_env_io(env);
 746         struct client_obd *cli = osc_cli(obj);
 747         int rc = 0;
 748
 749         if (!cli->cl_cache) /* shall not be in LRU */
 750                 return 0;
 751
 752         if (oio->oi_lru_reserved > 0) {
 753                 --oio->oi_lru_reserved;
 754                 goto out;
 755         }
 756
 757         LASSERT(atomic_long_read(cli->cl_lru_left) >= 0);
 758         while (!atomic_long_add_unless(cli->cl_lru_left, -1, 0)) {
 759                 /* run out of LRU spaces, try to drop some by itself */
 760                 rc = osc_lru_reclaim(cli);
 761                 if (rc < 0)
 762                         break;
 763                 if (rc > 0)
 764                         continue;
 765
 766                 cond_resched();
 767
 768                 rc = l_wait_event(osc_lru_waitq,
 769                                   atomic_long_read(cli->cl_lru_left) > 0,
 770                                   &lwi);
 771
 772                 if (rc < 0)
 773                         break;
 774         }
 775
 776 out:
 777         if (rc >= 0) {
 778                 atomic_long_inc(&cli->cl_lru_busy);
 779                 opg->ops_in_lru = 1;
 780                 rc = 0;
 781         }
 782
 783         return rc;
 784 }
 785
 786 /**
 787  * Atomic operations are expensive. We accumulate the accounting for the
 788  * same page pgdat to get better performance.
 789  * In practice this can work pretty good because the pages in the same RPC
 790  * are likely from the same page zone.
 791  */
 792 static inline void unstable_page_accounting(struct ptlrpc_bulk_desc *desc,
 793                                             int factor)
 794 {
 795         int page_count = desc->bd_iov_count;
 796         pg_data_t *last = NULL;
 797         int count = 0;
 798         int i;
 799
 800         for (i = 0; i < page_count; i++) {
 801                 pg_data_t *pgdat = page_pgdat(desc->bd_iov[i].bv_page);
 802
 803                 if (likely(pgdat == last)) {
 804                         ++count;
 805                         continue;
 806                 }
 807
 808                 if (count > 0) {
 809                         mod_node_page_state(pgdat, NR_UNSTABLE_NFS,
 810                                             factor * count);
 811                         count = 0;
 812                 }
 813                 last = pgdat;
 814                 ++count;
 815         }
 816         if (count > 0)
 817                 mod_node_page_state(last, NR_UNSTABLE_NFS, factor * count);
 818 }
 819
 820 static inline void add_unstable_page_accounting(struct ptlrpc_bulk_desc *desc)
 821 {
 822         unstable_page_accounting(desc, 1);
 823 }
 824
 825 static inline void dec_unstable_page_accounting(struct ptlrpc_bulk_desc *desc)
 826 {
 827         unstable_page_accounting(desc, -1);
 828 }
 829
 830 /**
 831  * Performs "unstable" page accounting. This function balances the
 832  * increment operations performed in osc_inc_unstable_pages. It is
 833  * registered as the RPC request callback, and is executed when the
 834  * bulk RPC is committed on the server. Thus at this point, the pages
 835  * involved in the bulk transfer are no longer considered unstable.
 836  *
 837  * If this function is called, the request should have been committed
 838  * or req:rq_unstable must have been set; it implies that the unstable
 839  * statistic have been added.
 840  */
 841 void osc_dec_unstable_pages(struct ptlrpc_request *req)
 842 {
 843         struct client_obd *cli = &req->rq_import->imp_obd->u.cli;
 844         struct ptlrpc_bulk_desc *desc = req->rq_bulk;
 845         int page_count = desc->bd_iov_count;
 846         long unstable_count;
 847
 848         LASSERT(page_count >= 0);
 849         dec_unstable_page_accounting(desc);
 850
 851         unstable_count = atomic_long_sub_return(page_count,
 852                                                 &cli->cl_unstable_count);
 853         LASSERT(unstable_count >= 0);
 854
 855         unstable_count = atomic_long_sub_return(page_count,
 856                                                 &cli->cl_cache->ccc_unstable_nr);
 857         LASSERT(unstable_count >= 0);
 858         if (!unstable_count)
 859                 wake_up_all(&cli->cl_cache->ccc_unstable_waitq);
 860
 861         if (osc_cache_too_much(cli))
 862                 (void)ptlrpcd_queue_work(cli->cl_lru_work);
 863 }
 864
 865 /**
 866  * "unstable" page accounting. See: osc_dec_unstable_pages.
 867  */
 868 void osc_inc_unstable_pages(struct ptlrpc_request *req)
 869 {
 870         struct client_obd *cli  = &req->rq_import->imp_obd->u.cli;
 871         struct ptlrpc_bulk_desc *desc = req->rq_bulk;
 872         long page_count = desc->bd_iov_count;
 873
 874         /* No unstable page tracking */
 875         if (!cli->cl_cache || !cli->cl_cache->ccc_unstable_check)
 876                 return;
 877
 878         add_unstable_page_accounting(desc);
 879         atomic_long_add(page_count, &cli->cl_unstable_count);
 880         atomic_long_add(page_count, &cli->cl_cache->ccc_unstable_nr);
 881
 882         /*
 883          * If the request has already been committed (i.e. brw_commit
 884          * called via rq_commit_cb), we need to undo the unstable page
 885          * increments we just performed because rq_commit_cb wont be
 886          * called again.
 887          */
 888         spin_lock(&req->rq_lock);
 889         if (unlikely(req->rq_committed)) {
 890                 spin_unlock(&req->rq_lock);
 891
 892                 osc_dec_unstable_pages(req);
 893         } else {
 894                 req->rq_unstable = 1;
 895                 spin_unlock(&req->rq_lock);
 896         }
 897 }
 898
 899 /**
 900  * Check if it piggybacks SOFT_SYNC flag to OST from this OSC.
 901  * This function will be called by every BRW RPC so it's critical
 902  * to make this function fast.
 903  */
 904 bool osc_over_unstable_soft_limit(struct client_obd *cli)
 905 {
 906         long unstable_nr, osc_unstable_count;
 907
 908         /* Can't check cli->cl_unstable_count, therefore, no soft limit */
 909         if (!cli->cl_cache || !cli->cl_cache->ccc_unstable_check)
 910                 return false;
 911
 912         osc_unstable_count = atomic_long_read(&cli->cl_unstable_count);
 913         unstable_nr = atomic_long_read(&cli->cl_cache->ccc_unstable_nr);
 914
 915         CDEBUG(D_CACHE,
 916                "%s: cli: %p unstable pages: %lu, osc unstable pages: %lu\n",
 917                cli->cl_import->imp_obd->obd_name, cli,
 918                unstable_nr, osc_unstable_count);
 919
 920         /*
 921          * If the LRU slots are in shortage - 25% remaining AND this OSC
 922          * has one full RPC window of unstable pages, it's a good chance
 923          * to piggyback a SOFT_SYNC flag.
 924          * Please notice that the OST won't take immediate response for the
 925          * SOFT_SYNC request so active OSCs will have more chance to carry
 926          * the flag, this is reasonable.
 927          */
 928         return unstable_nr > cli->cl_cache->ccc_lru_max >> 2 &&
 929                osc_unstable_count > cli->cl_max_pages_per_rpc *
 930                                     cli->cl_max_rpcs_in_flight;
 931 }
 932
 933 /** @} osc */