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[fs/lustre-release.git] / 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         union ldlm_policy_data *policy;
73         enum ldlm_mode          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
203 int osc_page_cache_add(const struct lu_env *env,
204                         const struct cl_page_slice *slice, struct cl_io *io)
205 {
206         struct osc_page *opg = cl2osc_page(slice);
207         int result;
208         ENTRY;
209
210         LINVRNT(osc_page_protected(env, opg, CLM_WRITE, 0));
211
212         osc_page_transfer_get(opg, "transfer\0cache");
213         result = osc_queue_async_io(env, io, opg);
214         if (result != 0)
215                 osc_page_transfer_put(env, opg);
216         else
217                 osc_page_transfer_add(env, opg, CRT_WRITE);
218
219         RETURN(result);
220 }
221
222 void osc_index2policy(union ldlm_policy_data *policy,
223                       const struct cl_object *obj, pgoff_t start, pgoff_t end)
224 {
225         memset(policy, 0, sizeof *policy);
226         policy->l_extent.start = cl_offset(obj, start);
227         policy->l_extent.end   = cl_offset(obj, end + 1) - 1;
228 }
229
230 static const char *osc_list(struct list_head *head)
231 {
232         return list_empty(head) ? "-" : "+";
233 }
234
235 static inline cfs_time_t osc_submit_duration(struct osc_page *opg)
236 {
237         if (opg->ops_submit_time == 0)
238                 return 0;
239
240         return (cfs_time_current() - opg->ops_submit_time);
241 }
242
243 static int osc_page_print(const struct lu_env *env,
244                           const struct cl_page_slice *slice,
245                           void *cookie, lu_printer_t printer)
246 {
247         struct osc_page       *opg = cl2osc_page(slice);
248         struct osc_async_page *oap = &opg->ops_oap;
249         struct osc_object     *obj = cl2osc(slice->cpl_obj);
250         struct client_obd     *cli = &osc_export(obj)->exp_obd->u.cli;
251
252         return (*printer)(env, cookie, LUSTRE_OSC_NAME"-page@%p %lu: "
253                           "1< %#x %d %u %s %s > "
254                           "2< "LPD64" %u %u %#x %#x | %p %p %p > "
255                           "3< %d %lu %d > "
256                           "4< %d %d %d %lu %s | %s %s %s %s > "
257                           "5< %s %s %s %s | %d %s | %d %s %s>\n",
258                           opg, osc_index(opg),
259                           /* 1 */
260                           oap->oap_magic, oap->oap_cmd,
261                           oap->oap_interrupted,
262                           osc_list(&oap->oap_pending_item),
263                           osc_list(&oap->oap_rpc_item),
264                           /* 2 */
265                           oap->oap_obj_off, oap->oap_page_off, oap->oap_count,
266                           oap->oap_async_flags, oap->oap_brw_flags,
267                           oap->oap_request, oap->oap_cli, obj,
268                           /* 3 */
269                           opg->ops_transfer_pinned,
270                           osc_submit_duration(opg), opg->ops_srvlock,
271                           /* 4 */
272                           cli->cl_r_in_flight, cli->cl_w_in_flight,
273                           cli->cl_max_rpcs_in_flight,
274                           cli->cl_avail_grant,
275                           osc_list(&cli->cl_cache_waiters),
276                           osc_list(&cli->cl_loi_ready_list),
277                           osc_list(&cli->cl_loi_hp_ready_list),
278                           osc_list(&cli->cl_loi_write_list),
279                           osc_list(&cli->cl_loi_read_list),
280                           /* 5 */
281                           osc_list(&obj->oo_ready_item),
282                           osc_list(&obj->oo_hp_ready_item),
283                           osc_list(&obj->oo_write_item),
284                           osc_list(&obj->oo_read_item),
285                           atomic_read(&obj->oo_nr_reads),
286                           osc_list(&obj->oo_reading_exts),
287                           atomic_read(&obj->oo_nr_writes),
288                           osc_list(&obj->oo_hp_exts),
289                           osc_list(&obj->oo_urgent_exts));
290 }
291
292 static void osc_page_delete(const struct lu_env *env,
293                             const struct cl_page_slice *slice)
294 {
295         struct osc_page   *opg = cl2osc_page(slice);
296         struct osc_object *obj = cl2osc(opg->ops_cl.cpl_obj);
297         int rc;
298
299         LINVRNT(opg->ops_temp || osc_page_protected(env, opg, CLM_READ, 1));
300
301         ENTRY;
302         CDEBUG(D_TRACE, "%p\n", opg);
303         osc_page_transfer_put(env, opg);
304         rc = osc_teardown_async_page(env, obj, opg);
305         if (rc) {
306                 CL_PAGE_DEBUG(D_ERROR, env, slice->cpl_page,
307                               "Trying to teardown failed: %d\n", rc);
308                 LASSERT(0);
309         }
310
311         osc_lru_del(osc_cli(obj), opg);
312
313         if (slice->cpl_page->cp_type == CPT_CACHEABLE) {
314                 void *value;
315
316                 spin_lock(&obj->oo_tree_lock);
317                 value = radix_tree_delete(&obj->oo_tree, osc_index(opg));
318                 if (value != NULL)
319                         --obj->oo_npages;
320                 spin_unlock(&obj->oo_tree_lock);
321
322                 LASSERT(ergo(value != NULL, value == opg));
323         }
324
325         EXIT;
326 }
327
328 static void osc_page_clip(const struct lu_env *env,
329                           const struct cl_page_slice *slice,
330                           int from, int to)
331 {
332         struct osc_page       *opg = cl2osc_page(slice);
333         struct osc_async_page *oap = &opg->ops_oap;
334
335         LINVRNT(osc_page_protected(env, opg, CLM_READ, 0));
336
337         opg->ops_from = from;
338         opg->ops_to   = to;
339         spin_lock(&oap->oap_lock);
340         oap->oap_async_flags |= ASYNC_COUNT_STABLE;
341         spin_unlock(&oap->oap_lock);
342 }
343
344 static int osc_page_cancel(const struct lu_env *env,
345                            const struct cl_page_slice *slice)
346 {
347         struct osc_page *opg = cl2osc_page(slice);
348         int rc = 0;
349
350         LINVRNT(osc_page_protected(env, opg, CLM_READ, 0));
351
352         /* Check if the transferring against this page
353          * is completed, or not even queued. */
354         if (opg->ops_transfer_pinned)
355                 /* FIXME: may not be interrupted.. */
356                 rc = osc_cancel_async_page(env, opg);
357         LASSERT(ergo(rc == 0, opg->ops_transfer_pinned == 0));
358         return rc;
359 }
360
361 static int osc_page_flush(const struct lu_env *env,
362                           const struct cl_page_slice *slice,
363                           struct cl_io *io)
364 {
365         struct osc_page *opg = cl2osc_page(slice);
366         int rc = 0;
367         ENTRY;
368         rc = osc_flush_async_page(env, io, opg);
369         RETURN(rc);
370 }
371
372 static const struct cl_page_operations osc_page_ops = {
373         .cpo_print         = osc_page_print,
374         .cpo_delete        = osc_page_delete,
375         .cpo_clip           = osc_page_clip,
376         .cpo_cancel         = osc_page_cancel,
377         .cpo_flush          = osc_page_flush
378 };
379
380 int osc_page_init(const struct lu_env *env, struct cl_object *obj,
381                   struct cl_page *page, pgoff_t index)
382 {
383         struct osc_object *osc = cl2osc(obj);
384         struct osc_page   *opg = cl_object_page_slice(obj, page);
385         int result;
386
387         opg->ops_from = 0;
388         opg->ops_to   = PAGE_CACHE_SIZE;
389
390         result = osc_prep_async_page(osc, opg, page->cp_vmpage,
391                                      cl_offset(obj, index));
392         if (result == 0) {
393                 struct osc_io *oio = osc_env_io(env);
394                 opg->ops_srvlock = osc_io_srvlock(oio);
395                 cl_page_slice_add(page, &opg->ops_cl, obj, index,
396                                   &osc_page_ops);
397         }
398         /*
399          * Cannot assert osc_page_protected() here as read-ahead
400          * creates temporary pages outside of a lock.
401          */
402 #ifdef CONFIG_LUSTRE_DEBUG_EXPENSIVE_CHECK
403         opg->ops_temp = !osc_page_protected(env, opg, CLM_READ, 1);
404 #endif
405         INIT_LIST_HEAD(&opg->ops_lru);
406
407         /* reserve an LRU space for this page */
408         if (page->cp_type == CPT_CACHEABLE && result == 0) {
409                 result = osc_lru_reserve(env, osc, opg);
410                 if (result == 0) {
411                         spin_lock(&osc->oo_tree_lock);
412                         result = radix_tree_insert(&osc->oo_tree, index, opg);
413                         if (result == 0)
414                                 ++osc->oo_npages;
415                         spin_unlock(&osc->oo_tree_lock);
416                         LASSERT(result == 0);
417                 }
418         }
419
420         return result;
421 }
422
423 /**
424  * Helper function called by osc_io_submit() for every page in an immediate
425  * transfer (i.e., transferred synchronously).
426  */
427 void osc_page_submit(const struct lu_env *env, struct osc_page *opg,
428                      enum cl_req_type crt, int brw_flags)
429 {
430         struct osc_async_page *oap = &opg->ops_oap;
431         struct osc_object     *obj = oap->oap_obj;
432
433         LINVRNT(osc_page_protected(env, opg,
434                                    crt == CRT_WRITE ? CLM_WRITE : CLM_READ, 1));
435
436         LASSERTF(oap->oap_magic == OAP_MAGIC, "Bad oap magic: oap %p, "
437                  "magic 0x%x\n", oap, oap->oap_magic);
438         LASSERT(oap->oap_async_flags & ASYNC_READY);
439         LASSERT(oap->oap_async_flags & ASYNC_COUNT_STABLE);
440
441         oap->oap_cmd       = crt == CRT_WRITE ? OBD_BRW_WRITE : OBD_BRW_READ;
442         oap->oap_page_off  = opg->ops_from;
443         oap->oap_count     = opg->ops_to - opg->ops_from;
444         oap->oap_brw_flags = OBD_BRW_SYNC | brw_flags;
445
446         if (!client_is_remote(osc_export(obj)) &&
447                         cfs_capable(CFS_CAP_SYS_RESOURCE)) {
448                 oap->oap_brw_flags |= OBD_BRW_NOQUOTA;
449                 oap->oap_cmd |= OBD_BRW_NOQUOTA;
450         }
451
452         opg->ops_submit_time = cfs_time_current();
453         osc_page_transfer_get(opg, "transfer\0imm");
454         osc_page_transfer_add(env, opg, crt);
455 }
456
457 /* --------------- LRU page management ------------------ */
458
459 /* OSC is a natural place to manage LRU pages as applications are specialized
460  * to write OSC by OSC. Ideally, if one OSC is used more frequently it should
461  * occupy more LRU slots. On the other hand, we should avoid using up all LRU
462  * slots (client_obd::cl_lru_left) otherwise process has to be put into sleep
463  * for free LRU slots - this will be very bad so the algorithm requires each
464  * OSC to free slots voluntarily to maintain a reasonable number of free slots
465  * at any time.
466  */
467
468 static DECLARE_WAIT_QUEUE_HEAD(osc_lru_waitq);
469
470 /**
471  * LRU pages are freed in batch mode. OSC should at least free this
472  * number of pages to avoid running out of LRU slots.
473  */
474 static inline int lru_shrink_min(struct client_obd *cli)
475 {
476         return cli->cl_max_pages_per_rpc * 2;
477 }
478
479 /**
480  * free this number at most otherwise it will take too long time to finsih.
481  */
482 static inline int lru_shrink_max(struct client_obd *cli)
483 {
484         return cli->cl_max_pages_per_rpc * cli->cl_max_rpcs_in_flight;
485 }
486
487 /**
488  * Check if we can free LRU slots from this OSC. If there exists LRU waiters,
489  * we should free slots aggressively. In this way, slots are freed in a steady
490  * step to maintain fairness among OSCs.
491  *
492  * Return how many LRU pages should be freed.
493  */
494 static int osc_cache_too_much(struct client_obd *cli)
495 {
496         struct cl_client_cache *cache = cli->cl_cache;
497         long pages = atomic_long_read(&cli->cl_lru_in_list);
498         unsigned long budget;
499
500         LASSERT(cache != NULL);
501         budget = cache->ccc_lru_max / (atomic_read(&cache->ccc_users) - 2);
502
503         /* if it's going to run out LRU slots, we should free some, but not
504          * too much to maintain faireness among OSCs. */
505         if (atomic_long_read(cli->cl_lru_left) < cache->ccc_lru_max >> 2) {
506                 if (pages >= budget)
507                         return lru_shrink_max(cli);
508                 else if (pages >= budget / 2)
509                         return lru_shrink_min(cli);
510         } else {
511                 int duration = cfs_time_current_sec() - cli->cl_lru_last_used;
512
513                 /* knock out pages by duration of no IO activity */
514                 duration >>= 6; /* approximately 1 minute */
515                 if (duration > 0 && pages >= budget / duration)
516                         return lru_shrink_min(cli);
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         int count;
525
526         CDEBUG(D_CACHE, "%s: run LRU work for client obd\n", cli_name(cli));
527         count = osc_cache_too_much(cli);
528         if (count > 0) {
529                 int rc = osc_lru_shrink(env, cli, count, false);
530
531                 CDEBUG(D_CACHE, "%s: shrank %d/%d pages from client obd\n",
532                        cli_name(cli), rc, count);
533                 if (rc >= count) {
534                         CDEBUG(D_CACHE, "%s: queue again\n", cli_name(cli));
535                         ptlrpcd_queue_work(cli->cl_lru_work);
536                 }
537         }
538
539         RETURN(0);
540 }
541
542 void osc_lru_add_batch(struct client_obd *cli, struct list_head *plist)
543 {
544         struct list_head lru = LIST_HEAD_INIT(lru);
545         struct osc_async_page *oap;
546         long npages = 0;
547
548         list_for_each_entry(oap, plist, oap_pending_item) {
549                 struct osc_page *opg = oap2osc_page(oap);
550
551                 if (!opg->ops_in_lru)
552                         continue;
553
554                 ++npages;
555                 LASSERT(list_empty(&opg->ops_lru));
556                 list_add(&opg->ops_lru, &lru);
557         }
558
559         if (npages > 0) {
560                 spin_lock(&cli->cl_lru_list_lock);
561                 list_splice_tail(&lru, &cli->cl_lru_list);
562                 atomic_long_sub(npages, &cli->cl_lru_busy);
563                 atomic_long_add(npages, &cli->cl_lru_in_list);
564                 cli->cl_lru_last_used = cfs_time_current_sec();
565                 spin_unlock(&cli->cl_lru_list_lock);
566
567                 if (waitqueue_active(&osc_lru_waitq))
568                         (void)ptlrpcd_queue_work(cli->cl_lru_work);
569         }
570 }
571
572 static void __osc_lru_del(struct client_obd *cli, struct osc_page *opg)
573 {
574         LASSERT(atomic_long_read(&cli->cl_lru_in_list) > 0);
575         list_del_init(&opg->ops_lru);
576         atomic_long_dec(&cli->cl_lru_in_list);
577 }
578
579 /**
580  * Page is being destroyed. The page may be not in LRU list, if the transfer
581  * has never finished(error occurred).
582  */
583 static void osc_lru_del(struct client_obd *cli, struct osc_page *opg)
584 {
585         if (opg->ops_in_lru) {
586                 spin_lock(&cli->cl_lru_list_lock);
587                 if (!list_empty(&opg->ops_lru)) {
588                         __osc_lru_del(cli, opg);
589                 } else {
590                         LASSERT(atomic_long_read(&cli->cl_lru_busy) > 0);
591                         atomic_long_dec(&cli->cl_lru_busy);
592                 }
593                 spin_unlock(&cli->cl_lru_list_lock);
594
595                 atomic_long_inc(cli->cl_lru_left);
596                 /* this is a great place to release more LRU pages if
597                  * this osc occupies too many LRU pages and kernel is
598                  * stealing one of them. */
599                 if (osc_cache_too_much(cli)) {
600                         CDEBUG(D_CACHE, "%s: queue LRU work\n", cli_name(cli));
601                         (void)ptlrpcd_queue_work(cli->cl_lru_work);
602                 }
603                 wake_up(&osc_lru_waitq);
604         } else {
605                 LASSERT(list_empty(&opg->ops_lru));
606         }
607 }
608
609 /**
610  * Delete page from LRUlist for redirty.
611  */
612 static void osc_lru_use(struct client_obd *cli, struct osc_page *opg)
613 {
614         /* If page is being transferred for the first time,
615          * ops_lru should be empty */
616         if (opg->ops_in_lru && !list_empty(&opg->ops_lru)) {
617                 spin_lock(&cli->cl_lru_list_lock);
618                 __osc_lru_del(cli, opg);
619                 spin_unlock(&cli->cl_lru_list_lock);
620                 atomic_long_inc(&cli->cl_lru_busy);
621         }
622 }
623
624 static void discard_pagevec(const struct lu_env *env, struct cl_io *io,
625                                 struct cl_page **pvec, int max_index)
626 {
627         int i;
628
629         for (i = 0; i < max_index; i++) {
630                 struct cl_page *page = pvec[i];
631
632                 LASSERT(cl_page_is_owned(page, io));
633                 cl_page_delete(env, page);
634                 cl_page_discard(env, io, page);
635                 cl_page_disown(env, io, page);
636                 cl_page_put(env, page);
637
638                 pvec[i] = NULL;
639         }
640 }
641
642 /**
643  * Check if a cl_page can be released, i.e, it's not being used.
644  *
645  * If unstable account is turned on, bulk transfer may hold one refcount
646  * for recovery so we need to check vmpage refcount as well; otherwise,
647  * even we can destroy cl_page but the corresponding vmpage can't be reused.
648  */
649 static inline bool lru_page_busy(struct client_obd *cli, struct cl_page *page)
650 {
651         if (cl_page_in_use_noref(page))
652                 return true;
653
654         if (cli->cl_cache->ccc_unstable_check) {
655                 struct page *vmpage = cl_page_vmpage(page);
656
657                 /* vmpage have two known users: cl_page and VM page cache */
658                 if (page_count(vmpage) - page_mapcount(vmpage) > 2)
659                         return true;
660         }
661         return false;
662 }
663
664 /**
665  * Drop @target of pages from LRU at most.
666  */
667 long osc_lru_shrink(const struct lu_env *env, struct client_obd *cli,
668                    long target, bool force)
669 {
670         struct cl_io *io;
671         struct cl_object *clobj = NULL;
672         struct cl_page **pvec;
673         struct osc_page *opg;
674         long count = 0;
675         int maxscan = 0;
676         int index = 0;
677         int rc = 0;
678         ENTRY;
679
680         LASSERT(atomic_long_read(&cli->cl_lru_in_list) >= 0);
681         if (atomic_long_read(&cli->cl_lru_in_list) == 0 || target <= 0)
682                 RETURN(0);
683
684         CDEBUG(D_CACHE, "%s: shrinkers: %d, force: %d\n",
685                cli_name(cli), atomic_read(&cli->cl_lru_shrinkers), force);
686         if (!force) {
687                 if (atomic_read(&cli->cl_lru_shrinkers) > 0)
688                         RETURN(-EBUSY);
689
690                 if (atomic_inc_return(&cli->cl_lru_shrinkers) > 1) {
691                         atomic_dec(&cli->cl_lru_shrinkers);
692                         RETURN(-EBUSY);
693                 }
694         } else {
695                 atomic_inc(&cli->cl_lru_shrinkers);
696         }
697
698         pvec = (struct cl_page **)osc_env_info(env)->oti_pvec;
699         io = &osc_env_info(env)->oti_io;
700
701         spin_lock(&cli->cl_lru_list_lock);
702         if (force)
703                 cli->cl_lru_reclaim++;
704         maxscan = min(target << 1, atomic_long_read(&cli->cl_lru_in_list));
705         while (!list_empty(&cli->cl_lru_list)) {
706                 struct cl_page *page;
707                 bool will_free = false;
708
709                 if (!force && atomic_read(&cli->cl_lru_shrinkers) > 1)
710                         break;
711
712                 if (--maxscan < 0)
713                         break;
714
715                 opg = list_entry(cli->cl_lru_list.next, struct osc_page,
716                                  ops_lru);
717                 page = opg->ops_cl.cpl_page;
718                 if (lru_page_busy(cli, page)) {
719                         list_move_tail(&opg->ops_lru, &cli->cl_lru_list);
720                         continue;
721                 }
722
723                 LASSERT(page->cp_obj != NULL);
724                 if (clobj != page->cp_obj) {
725                         struct cl_object *tmp = page->cp_obj;
726
727                         cl_object_get(tmp);
728                         spin_unlock(&cli->cl_lru_list_lock);
729
730                         if (clobj != NULL) {
731                                 discard_pagevec(env, io, pvec, index);
732                                 index = 0;
733
734                                 cl_io_fini(env, io);
735                                 cl_object_put(env, clobj);
736                                 clobj = NULL;
737                         }
738
739                         clobj = tmp;
740                         io->ci_obj = clobj;
741                         io->ci_ignore_layout = 1;
742                         rc = cl_io_init(env, io, CIT_MISC, clobj);
743
744                         spin_lock(&cli->cl_lru_list_lock);
745
746                         if (rc != 0)
747                                 break;
748
749                         ++maxscan;
750                         continue;
751                 }
752
753                 if (cl_page_own_try(env, io, page) == 0) {
754                         if (!lru_page_busy(cli, page)) {
755                                 /* remove it from lru list earlier to avoid
756                                  * lock contention */
757                                 __osc_lru_del(cli, opg);
758                                 opg->ops_in_lru = 0; /* will be discarded */
759
760                                 cl_page_get(page);
761                                 will_free = true;
762                         } else {
763                                 cl_page_disown(env, io, page);
764                         }
765                 }
766
767                 if (!will_free) {
768                         list_move_tail(&opg->ops_lru, &cli->cl_lru_list);
769                         continue;
770                 }
771
772                 /* Don't discard and free the page with cl_lru_list held */
773                 pvec[index++] = page;
774                 if (unlikely(index == OTI_PVEC_SIZE)) {
775                         spin_unlock(&cli->cl_lru_list_lock);
776                         discard_pagevec(env, io, pvec, index);
777                         index = 0;
778
779                         spin_lock(&cli->cl_lru_list_lock);
780                 }
781
782                 if (++count >= target)
783                         break;
784         }
785         spin_unlock(&cli->cl_lru_list_lock);
786
787         if (clobj != NULL) {
788                 discard_pagevec(env, io, pvec, index);
789
790                 cl_io_fini(env, io);
791                 cl_object_put(env, clobj);
792         }
793
794         atomic_dec(&cli->cl_lru_shrinkers);
795         if (count > 0) {
796                 atomic_long_add(count, cli->cl_lru_left);
797                 wake_up_all(&osc_lru_waitq);
798         }
799         RETURN(count > 0 ? count : rc);
800 }
801
802 /**
803  * Reclaim LRU pages by an IO thread. The caller wants to reclaim at least
804  * \@npages of LRU slots. For performance consideration, it's better to drop
805  * LRU pages in batch. Therefore, the actual number is adjusted at least
806  * max_pages_per_rpc.
807  */
808 long osc_lru_reclaim(struct client_obd *cli, unsigned long npages)
809 {
810         struct cl_env_nest nest;
811         struct lu_env *env;
812         struct cl_client_cache *cache = cli->cl_cache;
813         int max_scans;
814         long rc = 0;
815         ENTRY;
816
817         LASSERT(cache != NULL);
818
819         env = cl_env_nested_get(&nest);
820         if (IS_ERR(env))
821                 RETURN(rc);
822
823         npages = max_t(int, npages, cli->cl_max_pages_per_rpc);
824         CDEBUG(D_CACHE, "%s: start to reclaim %ld pages from LRU\n",
825                cli_name(cli), npages);
826         rc = osc_lru_shrink(env, cli, npages, true);
827         if (rc >= npages) {
828                 CDEBUG(D_CACHE, "%s: reclaimed %ld/%ld pages from LRU\n",
829                        cli_name(cli), rc, npages);
830                 if (osc_cache_too_much(cli) > 0)
831                         ptlrpcd_queue_work(cli->cl_lru_work);
832                 GOTO(out, rc);
833         } else if (rc > 0) {
834                 npages -= rc;
835         }
836
837         CDEBUG(D_CACHE, "%s: cli %p no free slots, pages: %ld/%ld, want: %ld\n",
838                 cli_name(cli), cli, atomic_long_read(&cli->cl_lru_in_list),
839                 atomic_long_read(&cli->cl_lru_busy), npages);
840
841         /* Reclaim LRU slots from other client_obd as it can't free enough
842          * from its own. This should rarely happen. */
843         spin_lock(&cache->ccc_lru_lock);
844         LASSERT(!list_empty(&cache->ccc_lru));
845
846         cache->ccc_lru_shrinkers++;
847         list_move_tail(&cli->cl_lru_osc, &cache->ccc_lru);
848
849         max_scans = atomic_read(&cache->ccc_users) - 2;
850         while (--max_scans > 0 && !list_empty(&cache->ccc_lru)) {
851                 cli = list_entry(cache->ccc_lru.next, struct client_obd,
852                                  cl_lru_osc);
853
854                 CDEBUG(D_CACHE, "%s: cli %p LRU pages: %ld, busy: %ld.\n",
855                         cli_name(cli), cli,
856                         atomic_long_read(&cli->cl_lru_in_list),
857                         atomic_long_read(&cli->cl_lru_busy));
858
859                 list_move_tail(&cli->cl_lru_osc, &cache->ccc_lru);
860                 if (osc_cache_too_much(cli) > 0) {
861                         spin_unlock(&cache->ccc_lru_lock);
862
863                         rc = osc_lru_shrink(env, cli, npages, true);
864                         spin_lock(&cache->ccc_lru_lock);
865                         if (rc >= npages)
866                                 break;
867                         if (rc > 0)
868                                 npages -= rc;
869                 }
870         }
871         spin_unlock(&cache->ccc_lru_lock);
872
873 out:
874         cl_env_nested_put(&nest, env);
875         CDEBUG(D_CACHE, "%s: cli %p freed %ld pages.\n",
876                 cli_name(cli), cli, rc);
877         return rc;
878 }
879
880 /**
881  * osc_lru_reserve() is called to reserve an LRU slot for a cl_page.
882  *
883  * Usually the LRU slots are reserved in osc_io_iter_rw_init().
884  * Only in the case that the LRU slots are in extreme shortage, it should
885  * have reserved enough slots for an IO.
886  */
887 static int osc_lru_reserve(const struct lu_env *env, struct osc_object *obj,
888                            struct osc_page *opg)
889 {
890         struct l_wait_info lwi = LWI_INTR(LWI_ON_SIGNAL_NOOP, NULL);
891         struct osc_io *oio = osc_env_io(env);
892         struct client_obd *cli = osc_cli(obj);
893         int rc = 0;
894         ENTRY;
895
896         if (cli->cl_cache == NULL) /* shall not be in LRU */
897                 RETURN(0);
898
899         if (oio->oi_lru_reserved > 0) {
900                 --oio->oi_lru_reserved;
901                 goto out;
902         }
903
904         LASSERT(atomic_long_read(cli->cl_lru_left) >= 0);
905         while (!atomic_long_add_unless(cli->cl_lru_left, -1, 0)) {
906                 /* run out of LRU spaces, try to drop some by itself */
907                 rc = osc_lru_reclaim(cli, 1);
908                 if (rc < 0)
909                         break;
910                 if (rc > 0)
911                         continue;
912
913                 cond_resched();
914                 rc = l_wait_event(osc_lru_waitq,
915                                 atomic_long_read(cli->cl_lru_left) > 0,
916                                 &lwi);
917                 if (rc < 0)
918                         break;
919         }
920
921 out:
922         if (rc >= 0) {
923                 atomic_long_inc(&cli->cl_lru_busy);
924                 opg->ops_in_lru = 1;
925                 rc = 0;
926         }
927
928         RETURN(rc);
929 }
930
931 /**
932  * Atomic operations are expensive. We accumulate the accounting for the
933  * same page zone to get better performance.
934  * In practice this can work pretty good because the pages in the same RPC
935  * are likely from the same page zone.
936  */
937 static inline void unstable_page_accounting(struct ptlrpc_bulk_desc *desc,
938                                             int factor)
939 {
940         int page_count = desc->bd_iov_count;
941         void *zone = NULL;
942         int count = 0;
943         int i;
944
945         LASSERT(ptlrpc_is_bulk_desc_kiov(desc->bd_type));
946
947         for (i = 0; i < page_count; i++) {
948                 void *pz = page_zone(BD_GET_KIOV(desc, i).kiov_page);
949
950                 if (likely(pz == zone)) {
951                         ++count;
952                         continue;
953                 }
954
955                 if (count > 0) {
956                         mod_zone_page_state(zone, NR_UNSTABLE_NFS,
957                                             factor * count);
958                         count = 0;
959                 }
960                 zone = pz;
961                 ++count;
962         }
963         if (count > 0)
964                 mod_zone_page_state(zone, NR_UNSTABLE_NFS, factor * count);
965 }
966
967 static inline void add_unstable_page_accounting(struct ptlrpc_bulk_desc *desc)
968 {
969         unstable_page_accounting(desc, 1);
970 }
971
972 static inline void dec_unstable_page_accounting(struct ptlrpc_bulk_desc *desc)
973 {
974         unstable_page_accounting(desc, -1);
975 }
976
977 /**
978  * Performs "unstable" page accounting. This function balances the
979  * increment operations performed in osc_inc_unstable_pages. It is
980  * registered as the RPC request callback, and is executed when the
981  * bulk RPC is committed on the server. Thus at this point, the pages
982  * involved in the bulk transfer are no longer considered unstable.
983  *
984  * If this function is called, the request should have been committed
985  * or req:rq_unstable must have been set; it implies that the unstable
986  * statistic have been added.
987  */
988 void osc_dec_unstable_pages(struct ptlrpc_request *req)
989 {
990         struct ptlrpc_bulk_desc *desc       = req->rq_bulk;
991         struct client_obd       *cli        = &req->rq_import->imp_obd->u.cli;
992         int                      page_count = desc->bd_iov_count;
993         long                     unstable_count;
994
995         LASSERT(page_count >= 0);
996         dec_unstable_page_accounting(desc);
997
998         unstable_count = atomic_long_sub_return(page_count,
999                                                 &cli->cl_unstable_count);
1000         LASSERT(unstable_count >= 0);
1001
1002         unstable_count = atomic_long_sub_return(page_count,
1003                                            &cli->cl_cache->ccc_unstable_nr);
1004         LASSERT(unstable_count >= 0);
1005         if (unstable_count == 0)
1006                 wake_up_all(&cli->cl_cache->ccc_unstable_waitq);
1007
1008         if (waitqueue_active(&osc_lru_waitq))
1009                 (void)ptlrpcd_queue_work(cli->cl_lru_work);
1010 }
1011
1012 /**
1013  * "unstable" page accounting. See: osc_dec_unstable_pages.
1014  */
1015 void osc_inc_unstable_pages(struct ptlrpc_request *req)
1016 {
1017         struct ptlrpc_bulk_desc *desc = req->rq_bulk;
1018         struct client_obd       *cli  = &req->rq_import->imp_obd->u.cli;
1019         long                     page_count = desc->bd_iov_count;
1020
1021         /* No unstable page tracking */
1022         if (cli->cl_cache == NULL || !cli->cl_cache->ccc_unstable_check)
1023                 return;
1024
1025         add_unstable_page_accounting(desc);
1026         atomic_long_add(page_count, &cli->cl_unstable_count);
1027         atomic_long_add(page_count, &cli->cl_cache->ccc_unstable_nr);
1028
1029         /* If the request has already been committed (i.e. brw_commit
1030          * called via rq_commit_cb), we need to undo the unstable page
1031          * increments we just performed because rq_commit_cb wont be
1032          * called again. */
1033         spin_lock(&req->rq_lock);
1034         if (unlikely(req->rq_committed)) {
1035                 spin_unlock(&req->rq_lock);
1036
1037                 osc_dec_unstable_pages(req);
1038         } else {
1039                 req->rq_unstable = 1;
1040                 spin_unlock(&req->rq_lock);
1041         }
1042 }
1043
1044 /**
1045  * Check if it piggybacks SOFT_SYNC flag to OST from this OSC.
1046  * This function will be called by every BRW RPC so it's critical
1047  * to make this function fast.
1048  */
1049 bool osc_over_unstable_soft_limit(struct client_obd *cli)
1050 {
1051         long unstable_nr, osc_unstable_count;
1052
1053         /* Can't check cli->cl_unstable_count, therefore, no soft limit */
1054         if (cli->cl_cache == NULL || !cli->cl_cache->ccc_unstable_check)
1055                 return false;
1056
1057         osc_unstable_count = atomic_long_read(&cli->cl_unstable_count);
1058         unstable_nr = atomic_long_read(&cli->cl_cache->ccc_unstable_nr);
1059
1060         CDEBUG(D_CACHE,
1061                "%s: cli: %p unstable pages: %lu, osc unstable pages: %lu\n",
1062                cli_name(cli), cli, unstable_nr, osc_unstable_count);
1063
1064         /* If the LRU slots are in shortage - 25% remaining AND this OSC
1065          * has one full RPC window of unstable pages, it's a good chance
1066          * to piggyback a SOFT_SYNC flag.
1067          * Please notice that the OST won't take immediate response for the
1068          * SOFT_SYNC request so active OSCs will have more chance to carry
1069          * the flag, this is reasonable. */
1070         return unstable_nr > cli->cl_cache->ccc_lru_max >> 2 &&
1071                osc_unstable_count > cli->cl_max_pages_per_rpc *
1072                                     cli->cl_max_rpcs_in_flight;
1073 }
1074
1075 /** @} osc */