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LU-9019 osc: migrate to 64 bit time
[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.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         /* ops_lru and ops_inflight share the same field, so take it from LRU
88          * first and then use it as inflight. */
89         osc_lru_use(osc_cli(obj), opg);
90 }
91
92 int osc_page_cache_add(const struct lu_env *env,
93                         const struct cl_page_slice *slice, struct cl_io *io)
94 {
95         struct osc_page *opg = cl2osc_page(slice);
96         int result;
97         ENTRY;
98
99         osc_page_transfer_get(opg, "transfer\0cache");
100         result = osc_queue_async_io(env, io, opg);
101         if (result != 0)
102                 osc_page_transfer_put(env, opg);
103         else
104                 osc_page_transfer_add(env, opg, CRT_WRITE);
105
106         RETURN(result);
107 }
108
109 void osc_index2policy(union ldlm_policy_data *policy,
110                       const struct cl_object *obj, pgoff_t start, pgoff_t end)
111 {
112         memset(policy, 0, sizeof *policy);
113         policy->l_extent.start = cl_offset(obj, start);
114         policy->l_extent.end   = cl_offset(obj, end + 1) - 1;
115 }
116
117 static const char *osc_list(struct list_head *head)
118 {
119         return list_empty(head) ? "-" : "+";
120 }
121
122 static inline s64 osc_submit_duration(struct osc_page *opg)
123 {
124         if (ktime_to_ns(opg->ops_submit_time) == 0)
125                 return 0;
126
127         return ktime_ms_delta(ktime_get(), opg->ops_submit_time);
128 }
129
130 static int osc_page_print(const struct lu_env *env,
131                           const struct cl_page_slice *slice,
132                           void *cookie, lu_printer_t printer)
133 {
134         struct osc_page       *opg = cl2osc_page(slice);
135         struct osc_async_page *oap = &opg->ops_oap;
136         struct osc_object     *obj = cl2osc(slice->cpl_obj);
137         struct client_obd     *cli = &osc_export(obj)->exp_obd->u.cli;
138
139         return (*printer)(env, cookie, LUSTRE_OSC_NAME"-page@%p %lu: "
140                           "1< %#x %d %u %s %s > "
141                           "2< %lld %u %u %#x %#x | %p %p %p > "
142                           "3< %d %lld %d > "
143                           "4< %d %d %d %lu %s | %s %s %s %s > "
144                           "5< %s %s %s %s | %d %s | %d %s %s>\n",
145                           opg, osc_index(opg),
146                           /* 1 */
147                           oap->oap_magic, oap->oap_cmd,
148                           oap->oap_interrupted,
149                           osc_list(&oap->oap_pending_item),
150                           osc_list(&oap->oap_rpc_item),
151                           /* 2 */
152                           oap->oap_obj_off, oap->oap_page_off, oap->oap_count,
153                           oap->oap_async_flags, oap->oap_brw_flags,
154                           oap->oap_request, oap->oap_cli, obj,
155                           /* 3 */
156                           opg->ops_transfer_pinned,
157                           osc_submit_duration(opg), opg->ops_srvlock,
158                           /* 4 */
159                           cli->cl_r_in_flight, cli->cl_w_in_flight,
160                           cli->cl_max_rpcs_in_flight,
161                           cli->cl_avail_grant,
162                           osc_list(&cli->cl_cache_waiters),
163                           osc_list(&cli->cl_loi_ready_list),
164                           osc_list(&cli->cl_loi_hp_ready_list),
165                           osc_list(&cli->cl_loi_write_list),
166                           osc_list(&cli->cl_loi_read_list),
167                           /* 5 */
168                           osc_list(&obj->oo_ready_item),
169                           osc_list(&obj->oo_hp_ready_item),
170                           osc_list(&obj->oo_write_item),
171                           osc_list(&obj->oo_read_item),
172                           atomic_read(&obj->oo_nr_reads),
173                           osc_list(&obj->oo_reading_exts),
174                           atomic_read(&obj->oo_nr_writes),
175                           osc_list(&obj->oo_hp_exts),
176                           osc_list(&obj->oo_urgent_exts));
177 }
178
179 static void osc_page_delete(const struct lu_env *env,
180                             const struct cl_page_slice *slice)
181 {
182         struct osc_page   *opg = cl2osc_page(slice);
183         struct osc_object *obj = cl2osc(opg->ops_cl.cpl_obj);
184         int rc;
185
186         ENTRY;
187         CDEBUG(D_TRACE, "%p\n", opg);
188         osc_page_transfer_put(env, opg);
189         rc = osc_teardown_async_page(env, obj, opg);
190         if (rc) {
191                 CL_PAGE_DEBUG(D_ERROR, env, slice->cpl_page,
192                               "Trying to teardown failed: %d\n", rc);
193                 LASSERT(0);
194         }
195
196         osc_lru_del(osc_cli(obj), opg);
197
198         if (slice->cpl_page->cp_type == CPT_CACHEABLE) {
199                 void *value;
200
201                 spin_lock(&obj->oo_tree_lock);
202                 value = radix_tree_delete(&obj->oo_tree, osc_index(opg));
203                 if (value != NULL)
204                         --obj->oo_npages;
205                 spin_unlock(&obj->oo_tree_lock);
206
207                 LASSERT(ergo(value != NULL, value == opg));
208         }
209
210         EXIT;
211 }
212
213 static void osc_page_clip(const struct lu_env *env,
214                           const struct cl_page_slice *slice,
215                           int from, int to)
216 {
217         struct osc_page       *opg = cl2osc_page(slice);
218         struct osc_async_page *oap = &opg->ops_oap;
219
220         opg->ops_from = from;
221         opg->ops_to   = to;
222         spin_lock(&oap->oap_lock);
223         oap->oap_async_flags |= ASYNC_COUNT_STABLE;
224         spin_unlock(&oap->oap_lock);
225 }
226
227 static int osc_page_cancel(const struct lu_env *env,
228                            const struct cl_page_slice *slice)
229 {
230         struct osc_page *opg = cl2osc_page(slice);
231         int rc = 0;
232
233         /* Check if the transferring against this page
234          * is completed, or not even queued. */
235         if (opg->ops_transfer_pinned)
236                 /* FIXME: may not be interrupted.. */
237                 rc = osc_cancel_async_page(env, opg);
238         LASSERT(ergo(rc == 0, opg->ops_transfer_pinned == 0));
239         return rc;
240 }
241
242 static int osc_page_flush(const struct lu_env *env,
243                           const struct cl_page_slice *slice,
244                           struct cl_io *io)
245 {
246         struct osc_page *opg = cl2osc_page(slice);
247         int rc = 0;
248         ENTRY;
249         rc = osc_flush_async_page(env, io, opg);
250         RETURN(rc);
251 }
252
253 static const struct cl_page_operations osc_page_ops = {
254         .cpo_print         = osc_page_print,
255         .cpo_delete        = osc_page_delete,
256         .cpo_clip           = osc_page_clip,
257         .cpo_cancel         = osc_page_cancel,
258         .cpo_flush          = osc_page_flush
259 };
260
261 int osc_page_init(const struct lu_env *env, struct cl_object *obj,
262                   struct cl_page *page, pgoff_t index)
263 {
264         struct osc_object *osc = cl2osc(obj);
265         struct osc_page   *opg = cl_object_page_slice(obj, page);
266         struct osc_io *oio = osc_env_io(env);
267         int result;
268
269         opg->ops_from = 0;
270         opg->ops_to   = PAGE_SIZE;
271
272         INIT_LIST_HEAD(&opg->ops_lru);
273
274         result = osc_prep_async_page(osc, opg, page->cp_vmpage,
275                                      cl_offset(obj, index));
276         if (result != 0)
277                 return result;
278
279         opg->ops_srvlock = osc_io_srvlock(oio);
280         cl_page_slice_add(page, &opg->ops_cl, obj, index,
281                           &osc_page_ops);
282
283
284         /* reserve an LRU space for this page */
285         if (page->cp_type == CPT_CACHEABLE) {
286                 result = osc_lru_alloc(env, osc_cli(osc), opg);
287                 if (result == 0) {
288                         result = radix_tree_preload(GFP_NOFS);
289                         if (result == 0) {
290                                 spin_lock(&osc->oo_tree_lock);
291                                 result = radix_tree_insert(&osc->oo_tree,
292                                                            index, opg);
293                                 if (result == 0)
294                                         ++osc->oo_npages;
295                                 spin_unlock(&osc->oo_tree_lock);
296
297                                 radix_tree_preload_end();
298                         }
299                 }
300         }
301
302         return result;
303 }
304 EXPORT_SYMBOL(osc_page_init);
305
306 /**
307  * Helper function called by osc_io_submit() for every page in an immediate
308  * transfer (i.e., transferred synchronously).
309  */
310 void osc_page_submit(const struct lu_env *env, struct osc_page *opg,
311                      enum cl_req_type crt, int brw_flags)
312 {
313         struct osc_async_page *oap = &opg->ops_oap;
314
315         LASSERTF(oap->oap_magic == OAP_MAGIC, "Bad oap magic: oap %p, "
316                  "magic 0x%x\n", oap, oap->oap_magic);
317         LASSERT(oap->oap_async_flags & ASYNC_READY);
318         LASSERT(oap->oap_async_flags & ASYNC_COUNT_STABLE);
319
320         oap->oap_cmd       = crt == CRT_WRITE ? OBD_BRW_WRITE : OBD_BRW_READ;
321         oap->oap_page_off  = opg->ops_from;
322         oap->oap_count     = opg->ops_to - opg->ops_from;
323         oap->oap_brw_flags = OBD_BRW_SYNC | brw_flags;
324
325         if (cfs_capable(CFS_CAP_SYS_RESOURCE)) {
326                 oap->oap_brw_flags |= OBD_BRW_NOQUOTA;
327                 oap->oap_cmd |= OBD_BRW_NOQUOTA;
328         }
329
330         opg->ops_submit_time = ktime_get();
331         osc_page_transfer_get(opg, "transfer\0imm");
332         osc_page_transfer_add(env, opg, crt);
333 }
334
335 /* --------------- LRU page management ------------------ */
336
337 /* OSC is a natural place to manage LRU pages as applications are specialized
338  * to write OSC by OSC. Ideally, if one OSC is used more frequently it should
339  * occupy more LRU slots. On the other hand, we should avoid using up all LRU
340  * slots (client_obd::cl_lru_left) otherwise process has to be put into sleep
341  * for free LRU slots - this will be very bad so the algorithm requires each
342  * OSC to free slots voluntarily to maintain a reasonable number of free slots
343  * at any time.
344  */
345
346 static DECLARE_WAIT_QUEUE_HEAD(osc_lru_waitq);
347
348 /**
349  * LRU pages are freed in batch mode. OSC should at least free this
350  * number of pages to avoid running out of LRU slots.
351  */
352 static inline int lru_shrink_min(struct client_obd *cli)
353 {
354         return cli->cl_max_pages_per_rpc * 2;
355 }
356
357 /**
358  * free this number at most otherwise it will take too long time to finsih.
359  */
360 static inline int lru_shrink_max(struct client_obd *cli)
361 {
362         return cli->cl_max_pages_per_rpc * cli->cl_max_rpcs_in_flight;
363 }
364
365 /**
366  * Check if we can free LRU slots from this OSC. If there exists LRU waiters,
367  * we should free slots aggressively. In this way, slots are freed in a steady
368  * step to maintain fairness among OSCs.
369  *
370  * Return how many LRU pages should be freed.
371  */
372 static int osc_cache_too_much(struct client_obd *cli)
373 {
374         struct cl_client_cache *cache = cli->cl_cache;
375         long pages = atomic_long_read(&cli->cl_lru_in_list);
376         unsigned long budget;
377
378         LASSERT(cache != NULL);
379         budget = cache->ccc_lru_max / (atomic_read(&cache->ccc_users) - 2);
380
381         /* if it's going to run out LRU slots, we should free some, but not
382          * too much to maintain faireness among OSCs. */
383         if (atomic_long_read(cli->cl_lru_left) < cache->ccc_lru_max >> 2) {
384                 if (pages >= budget)
385                         return lru_shrink_max(cli);
386                 else if (pages >= budget / 2)
387                         return lru_shrink_min(cli);
388         } else {
389                 time64_t duration = ktime_get_real_seconds();
390                 long timediff;
391
392                 /* knock out pages by duration of no IO activity */
393                 duration -= cli->cl_lru_last_used;
394                 /*
395                  * The difference shouldn't be more than 70 years
396                  * so we can safely case to a long. Round to
397                  * approximately 1 minute.
398                  */
399                 timediff = (long)(duration >> 6);
400                 if (timediff > 0 && pages >= budget / timediff)
401                         return lru_shrink_min(cli);
402         }
403         return 0;
404 }
405
406 int lru_queue_work(const struct lu_env *env, void *data)
407 {
408         struct client_obd *cli = data;
409         int count;
410
411         CDEBUG(D_CACHE, "%s: run LRU work for client obd\n", cli_name(cli));
412         count = osc_cache_too_much(cli);
413         if (count > 0) {
414                 int rc = osc_lru_shrink(env, cli, count, false);
415
416                 CDEBUG(D_CACHE, "%s: shrank %d/%d pages from client obd\n",
417                        cli_name(cli), rc, count);
418                 if (rc >= count) {
419                         CDEBUG(D_CACHE, "%s: queue again\n", cli_name(cli));
420                         ptlrpcd_queue_work(cli->cl_lru_work);
421                 }
422         }
423
424         RETURN(0);
425 }
426
427 void osc_lru_add_batch(struct client_obd *cli, struct list_head *plist)
428 {
429         struct list_head lru = LIST_HEAD_INIT(lru);
430         struct osc_async_page *oap;
431         long npages = 0;
432
433         list_for_each_entry(oap, plist, oap_pending_item) {
434                 struct osc_page *opg = oap2osc_page(oap);
435
436                 if (!opg->ops_in_lru)
437                         continue;
438
439                 ++npages;
440                 LASSERT(list_empty(&opg->ops_lru));
441                 list_add(&opg->ops_lru, &lru);
442         }
443
444         if (npages > 0) {
445                 spin_lock(&cli->cl_lru_list_lock);
446                 list_splice_tail(&lru, &cli->cl_lru_list);
447                 atomic_long_sub(npages, &cli->cl_lru_busy);
448                 atomic_long_add(npages, &cli->cl_lru_in_list);
449                 cli->cl_lru_last_used = ktime_get_real_seconds();
450                 spin_unlock(&cli->cl_lru_list_lock);
451
452                 if (waitqueue_active(&osc_lru_waitq))
453                         (void)ptlrpcd_queue_work(cli->cl_lru_work);
454         }
455 }
456
457 static void __osc_lru_del(struct client_obd *cli, struct osc_page *opg)
458 {
459         LASSERT(atomic_long_read(&cli->cl_lru_in_list) > 0);
460         list_del_init(&opg->ops_lru);
461         atomic_long_dec(&cli->cl_lru_in_list);
462 }
463
464 /**
465  * Page is being destroyed. The page may be not in LRU list, if the transfer
466  * has never finished(error occurred).
467  */
468 static void osc_lru_del(struct client_obd *cli, struct osc_page *opg)
469 {
470         if (opg->ops_in_lru) {
471                 spin_lock(&cli->cl_lru_list_lock);
472                 if (!list_empty(&opg->ops_lru)) {
473                         __osc_lru_del(cli, opg);
474                 } else {
475                         LASSERT(atomic_long_read(&cli->cl_lru_busy) > 0);
476                         atomic_long_dec(&cli->cl_lru_busy);
477                 }
478                 spin_unlock(&cli->cl_lru_list_lock);
479
480                 atomic_long_inc(cli->cl_lru_left);
481                 /* this is a great place to release more LRU pages if
482                  * this osc occupies too many LRU pages and kernel is
483                  * stealing one of them. */
484                 if (osc_cache_too_much(cli)) {
485                         CDEBUG(D_CACHE, "%s: queue LRU work\n", cli_name(cli));
486                         (void)ptlrpcd_queue_work(cli->cl_lru_work);
487                 }
488                 wake_up(&osc_lru_waitq);
489         } else {
490                 LASSERT(list_empty(&opg->ops_lru));
491         }
492 }
493
494 /**
495  * Delete page from LRU list for redirty.
496  */
497 static void osc_lru_use(struct client_obd *cli, struct osc_page *opg)
498 {
499         /* If page is being transferred for the first time,
500          * ops_lru should be empty */
501         if (opg->ops_in_lru) {
502                 spin_lock(&cli->cl_lru_list_lock);
503                 if (!list_empty(&opg->ops_lru)) {
504                         __osc_lru_del(cli, opg);
505                         atomic_long_inc(&cli->cl_lru_busy);
506                 }
507                 spin_unlock(&cli->cl_lru_list_lock);
508         }
509 }
510
511 static void discard_pagevec(const struct lu_env *env, struct cl_io *io,
512                                 struct cl_page **pvec, int max_index)
513 {
514         int i;
515
516         for (i = 0; i < max_index; i++) {
517                 struct cl_page *page = pvec[i];
518
519                 LASSERT(cl_page_is_owned(page, io));
520                 cl_page_delete(env, page);
521                 cl_page_discard(env, io, page);
522                 cl_page_disown(env, io, page);
523                 cl_page_put(env, page);
524
525                 pvec[i] = NULL;
526         }
527 }
528
529 /**
530  * Check if a cl_page can be released, i.e, it's not being used.
531  *
532  * If unstable account is turned on, bulk transfer may hold one refcount
533  * for recovery so we need to check vmpage refcount as well; otherwise,
534  * even we can destroy cl_page but the corresponding vmpage can't be reused.
535  */
536 static inline bool lru_page_busy(struct client_obd *cli, struct cl_page *page)
537 {
538         if (cl_page_in_use_noref(page))
539                 return true;
540
541         if (cli->cl_cache->ccc_unstable_check) {
542                 struct page *vmpage = cl_page_vmpage(page);
543
544                 /* vmpage have two known users: cl_page and VM page cache */
545                 if (page_count(vmpage) - page_mapcount(vmpage) > 2)
546                         return true;
547         }
548         return false;
549 }
550
551 /**
552  * Drop @target of pages from LRU at most.
553  */
554 long osc_lru_shrink(const struct lu_env *env, struct client_obd *cli,
555                    long target, bool force)
556 {
557         struct cl_io *io;
558         struct cl_object *clobj = NULL;
559         struct cl_page **pvec;
560         struct osc_page *opg;
561         long count = 0;
562         int maxscan = 0;
563         int index = 0;
564         int rc = 0;
565         ENTRY;
566
567         LASSERT(atomic_long_read(&cli->cl_lru_in_list) >= 0);
568         if (atomic_long_read(&cli->cl_lru_in_list) == 0 || target <= 0)
569                 RETURN(0);
570
571         CDEBUG(D_CACHE, "%s: shrinkers: %d, force: %d\n",
572                cli_name(cli), atomic_read(&cli->cl_lru_shrinkers), force);
573         if (!force) {
574                 if (atomic_read(&cli->cl_lru_shrinkers) > 0)
575                         RETURN(-EBUSY);
576
577                 if (atomic_inc_return(&cli->cl_lru_shrinkers) > 1) {
578                         atomic_dec(&cli->cl_lru_shrinkers);
579                         RETURN(-EBUSY);
580                 }
581         } else {
582                 atomic_inc(&cli->cl_lru_shrinkers);
583         }
584
585         pvec = (struct cl_page **)osc_env_info(env)->oti_pvec;
586         io = osc_env_thread_io(env);
587
588         spin_lock(&cli->cl_lru_list_lock);
589         if (force)
590                 cli->cl_lru_reclaim++;
591         maxscan = min(target << 1, atomic_long_read(&cli->cl_lru_in_list));
592         while (!list_empty(&cli->cl_lru_list)) {
593                 struct cl_page *page;
594                 bool will_free = false;
595
596                 if (!force && atomic_read(&cli->cl_lru_shrinkers) > 1)
597                         break;
598
599                 if (--maxscan < 0)
600                         break;
601
602                 opg = list_entry(cli->cl_lru_list.next, struct osc_page,
603                                  ops_lru);
604                 page = opg->ops_cl.cpl_page;
605                 if (lru_page_busy(cli, page)) {
606                         list_move_tail(&opg->ops_lru, &cli->cl_lru_list);
607                         continue;
608                 }
609
610                 LASSERT(page->cp_obj != NULL);
611                 if (clobj != page->cp_obj) {
612                         struct cl_object *tmp = page->cp_obj;
613
614                         cl_object_get(tmp);
615                         spin_unlock(&cli->cl_lru_list_lock);
616
617                         if (clobj != NULL) {
618                                 discard_pagevec(env, io, pvec, index);
619                                 index = 0;
620
621                                 cl_io_fini(env, io);
622                                 cl_object_put(env, clobj);
623                                 clobj = NULL;
624                         }
625
626                         clobj = tmp;
627                         io->ci_obj = clobj;
628                         io->ci_ignore_layout = 1;
629                         rc = cl_io_init(env, io, CIT_MISC, clobj);
630
631                         spin_lock(&cli->cl_lru_list_lock);
632
633                         if (rc != 0)
634                                 break;
635
636                         ++maxscan;
637                         continue;
638                 }
639
640                 if (cl_page_own_try(env, io, page) == 0) {
641                         if (!lru_page_busy(cli, page)) {
642                                 /* remove it from lru list earlier to avoid
643                                  * lock contention */
644                                 __osc_lru_del(cli, opg);
645                                 opg->ops_in_lru = 0; /* will be discarded */
646
647                                 cl_page_get(page);
648                                 will_free = true;
649                         } else {
650                                 cl_page_disown(env, io, page);
651                         }
652                 }
653
654                 if (!will_free) {
655                         list_move_tail(&opg->ops_lru, &cli->cl_lru_list);
656                         continue;
657                 }
658
659                 /* Don't discard and free the page with cl_lru_list held */
660                 pvec[index++] = page;
661                 if (unlikely(index == OTI_PVEC_SIZE)) {
662                         spin_unlock(&cli->cl_lru_list_lock);
663                         discard_pagevec(env, io, pvec, index);
664                         index = 0;
665
666                         spin_lock(&cli->cl_lru_list_lock);
667                 }
668
669                 if (++count >= target)
670                         break;
671         }
672         spin_unlock(&cli->cl_lru_list_lock);
673
674         if (clobj != NULL) {
675                 discard_pagevec(env, io, pvec, index);
676
677                 cl_io_fini(env, io);
678                 cl_object_put(env, clobj);
679         }
680
681         atomic_dec(&cli->cl_lru_shrinkers);
682         if (count > 0) {
683                 atomic_long_add(count, cli->cl_lru_left);
684                 wake_up_all(&osc_lru_waitq);
685         }
686         RETURN(count > 0 ? count : rc);
687 }
688 EXPORT_SYMBOL(osc_lru_shrink);
689
690 /**
691  * Reclaim LRU pages by an IO thread. The caller wants to reclaim at least
692  * \@npages of LRU slots. For performance consideration, it's better to drop
693  * LRU pages in batch. Therefore, the actual number is adjusted at least
694  * max_pages_per_rpc.
695  */
696 static long osc_lru_reclaim(struct client_obd *cli, unsigned long npages)
697 {
698         struct lu_env *env;
699         struct cl_client_cache *cache = cli->cl_cache;
700         int max_scans;
701         __u16 refcheck;
702         long rc = 0;
703         ENTRY;
704
705         LASSERT(cache != NULL);
706
707         env = cl_env_get(&refcheck);
708         if (IS_ERR(env))
709                 RETURN(rc);
710
711         npages = max_t(int, npages, cli->cl_max_pages_per_rpc);
712         CDEBUG(D_CACHE, "%s: start to reclaim %ld pages from LRU\n",
713                cli_name(cli), npages);
714         rc = osc_lru_shrink(env, cli, npages, true);
715         if (rc >= npages) {
716                 CDEBUG(D_CACHE, "%s: reclaimed %ld/%ld pages from LRU\n",
717                        cli_name(cli), rc, npages);
718                 if (osc_cache_too_much(cli) > 0)
719                         ptlrpcd_queue_work(cli->cl_lru_work);
720                 GOTO(out, rc);
721         } else if (rc > 0) {
722                 npages -= rc;
723         }
724
725         CDEBUG(D_CACHE, "%s: cli %p no free slots, pages: %ld/%ld, want: %ld\n",
726                 cli_name(cli), cli, atomic_long_read(&cli->cl_lru_in_list),
727                 atomic_long_read(&cli->cl_lru_busy), npages);
728
729         /* Reclaim LRU slots from other client_obd as it can't free enough
730          * from its own. This should rarely happen. */
731         spin_lock(&cache->ccc_lru_lock);
732         LASSERT(!list_empty(&cache->ccc_lru));
733
734         cache->ccc_lru_shrinkers++;
735         list_move_tail(&cli->cl_lru_osc, &cache->ccc_lru);
736
737         max_scans = atomic_read(&cache->ccc_users) - 2;
738         while (--max_scans > 0 && !list_empty(&cache->ccc_lru)) {
739                 cli = list_entry(cache->ccc_lru.next, struct client_obd,
740                                  cl_lru_osc);
741
742                 CDEBUG(D_CACHE, "%s: cli %p LRU pages: %ld, busy: %ld.\n",
743                         cli_name(cli), cli,
744                         atomic_long_read(&cli->cl_lru_in_list),
745                         atomic_long_read(&cli->cl_lru_busy));
746
747                 list_move_tail(&cli->cl_lru_osc, &cache->ccc_lru);
748                 if (osc_cache_too_much(cli) > 0) {
749                         spin_unlock(&cache->ccc_lru_lock);
750
751                         rc = osc_lru_shrink(env, cli, npages, true);
752                         spin_lock(&cache->ccc_lru_lock);
753                         if (rc >= npages)
754                                 break;
755                         if (rc > 0)
756                                 npages -= rc;
757                 }
758         }
759         spin_unlock(&cache->ccc_lru_lock);
760
761 out:
762         cl_env_put(env, &refcheck);
763         CDEBUG(D_CACHE, "%s: cli %p freed %ld pages.\n",
764                 cli_name(cli), cli, rc);
765         return rc;
766 }
767
768 /**
769  * osc_lru_alloc() is called to allocate an LRU slot for a cl_page.
770  *
771  * Usually the LRU slots are reserved in osc_io_iter_rw_init().
772  * Only in the case that the LRU slots are in extreme shortage, it should
773  * have reserved enough slots for an IO.
774  */
775 static int osc_lru_alloc(const struct lu_env *env, struct client_obd *cli,
776                          struct osc_page *opg)
777 {
778         struct l_wait_info lwi = LWI_INTR(LWI_ON_SIGNAL_NOOP, NULL);
779         struct osc_io *oio = osc_env_io(env);
780         int rc = 0;
781
782         ENTRY;
783
784         if (cli->cl_cache == NULL) /* shall not be in LRU */
785                 RETURN(0);
786
787         if (oio->oi_lru_reserved > 0) {
788                 --oio->oi_lru_reserved;
789                 goto out;
790         }
791
792         LASSERT(atomic_long_read(cli->cl_lru_left) >= 0);
793         while (!atomic_long_add_unless(cli->cl_lru_left, -1, 0)) {
794                 /* run out of LRU spaces, try to drop some by itself */
795                 rc = osc_lru_reclaim(cli, 1);
796                 if (rc < 0)
797                         break;
798                 if (rc > 0)
799                         continue;
800
801                 cond_resched();
802                 rc = l_wait_event(osc_lru_waitq,
803                                 atomic_long_read(cli->cl_lru_left) > 0,
804                                 &lwi);
805                 if (rc < 0)
806                         break;
807         }
808
809 out:
810         if (rc >= 0) {
811                 atomic_long_inc(&cli->cl_lru_busy);
812                 opg->ops_in_lru = 1;
813                 rc = 0;
814         }
815
816         RETURN(rc);
817 }
818
819 /**
820  * osc_lru_reserve() is called to reserve enough LRU slots for I/O.
821  *
822  * The benefit of doing this is to reduce contention against atomic counter
823  * cl_lru_left by changing it from per-page access to per-IO access.
824  */
825 unsigned long osc_lru_reserve(struct client_obd *cli, unsigned long npages)
826 {
827         unsigned long reserved = 0;
828         unsigned long max_pages;
829         unsigned long c;
830
831         /* reserve a full RPC window at most to avoid that a thread accidentally
832          * consumes too many LRU slots */
833         max_pages = cli->cl_max_pages_per_rpc * cli->cl_max_rpcs_in_flight;
834         if (npages > max_pages)
835                 npages = max_pages;
836
837         c = atomic_long_read(cli->cl_lru_left);
838         if (c < npages && osc_lru_reclaim(cli, npages) > 0)
839                 c = atomic_long_read(cli->cl_lru_left);
840         while (c >= npages) {
841                 if (c == atomic_long_cmpxchg(cli->cl_lru_left, c, c - npages)) {
842                         reserved = npages;
843                         break;
844                 }
845                 c = atomic_long_read(cli->cl_lru_left);
846         }
847         if (atomic_long_read(cli->cl_lru_left) < max_pages) {
848                 /* If there aren't enough pages in the per-OSC LRU then
849                  * wake up the LRU thread to try and clear out space, so
850                  * we don't block if pages are being dirtied quickly. */
851                 CDEBUG(D_CACHE, "%s: queue LRU, left: %lu/%ld.\n",
852                        cli_name(cli), atomic_long_read(cli->cl_lru_left),
853                        max_pages);
854                 (void)ptlrpcd_queue_work(cli->cl_lru_work);
855         }
856
857         return reserved;
858 }
859
860 /**
861  * osc_lru_unreserve() is called to unreserve LRU slots.
862  *
863  * LRU slots reserved by osc_lru_reserve() may have entries left due to several
864  * reasons such as page already existing or I/O error. Those reserved slots
865  * should be freed by calling this function.
866  */
867 void osc_lru_unreserve(struct client_obd *cli, unsigned long npages)
868 {
869         atomic_long_add(npages, cli->cl_lru_left);
870         wake_up_all(&osc_lru_waitq);
871 }
872
873 /**
874  * Atomic operations are expensive. We accumulate the accounting for the
875  * same page zone to get better performance.
876  * In practice this can work pretty good because the pages in the same RPC
877  * are likely from the same page zone.
878  */
879 static inline void unstable_page_accounting(struct ptlrpc_bulk_desc *desc,
880                                             struct osc_brw_async_args *aa,
881                                             int factor)
882 {
883         int page_count;
884         void *zone = NULL;
885         int count = 0;
886         int i;
887
888         if (desc != NULL) {
889                 LASSERT(ptlrpc_is_bulk_desc_kiov(desc->bd_type));
890                 page_count = desc->bd_iov_count;
891         } else {
892                 page_count = aa->aa_page_count;
893         }
894
895         for (i = 0; i < page_count; i++) {
896                 void *pz;
897                 if (desc)
898                         pz = page_zone(BD_GET_KIOV(desc, i).kiov_page);
899                 else
900                         pz = page_zone(aa->aa_ppga[i]->pg);
901
902                 if (likely(pz == zone)) {
903                         ++count;
904                         continue;
905                 }
906
907                 if (count > 0) {
908                         mod_zone_page_state(zone, NR_UNSTABLE_NFS,
909                                             factor * count);
910                         count = 0;
911                 }
912                 zone = pz;
913                 ++count;
914         }
915         if (count > 0)
916                 mod_zone_page_state(zone, NR_UNSTABLE_NFS, factor * count);
917 }
918
919 static inline void add_unstable_page_accounting(struct ptlrpc_bulk_desc *desc,
920                                                 struct osc_brw_async_args *aa)
921 {
922         unstable_page_accounting(desc, aa, 1);
923 }
924
925 static inline void dec_unstable_page_accounting(struct ptlrpc_bulk_desc *desc,
926                                                 struct osc_brw_async_args *aa)
927 {
928         unstable_page_accounting(desc, aa, -1);
929 }
930
931 /**
932  * Performs "unstable" page accounting. This function balances the
933  * increment operations performed in osc_inc_unstable_pages. It is
934  * registered as the RPC request callback, and is executed when the
935  * bulk RPC is committed on the server. Thus at this point, the pages
936  * involved in the bulk transfer are no longer considered unstable.
937  *
938  * If this function is called, the request should have been committed
939  * or req:rq_unstable must have been set; it implies that the unstable
940  * statistic have been added.
941  */
942 void osc_dec_unstable_pages(struct ptlrpc_request *req)
943 {
944         struct ptlrpc_bulk_desc *desc       = req->rq_bulk;
945         struct osc_brw_async_args *aa = (void *)&req->rq_async_args;
946         struct client_obd       *cli        = &req->rq_import->imp_obd->u.cli;
947         int                      page_count;
948         long                     unstable_count;
949
950         if (desc)
951                 page_count = desc->bd_iov_count;
952         else
953                 page_count = aa->aa_page_count;
954
955         LASSERT(page_count >= 0);
956
957         dec_unstable_page_accounting(desc, aa);
958
959         unstable_count = atomic_long_sub_return(page_count,
960                                                 &cli->cl_unstable_count);
961         LASSERT(unstable_count >= 0);
962
963         unstable_count = atomic_long_sub_return(page_count,
964                                            &cli->cl_cache->ccc_unstable_nr);
965         LASSERT(unstable_count >= 0);
966         if (unstable_count == 0)
967                 wake_up_all(&cli->cl_cache->ccc_unstable_waitq);
968
969         if (waitqueue_active(&osc_lru_waitq))
970                 (void)ptlrpcd_queue_work(cli->cl_lru_work);
971 }
972
973 /**
974  * "unstable" page accounting. See: osc_dec_unstable_pages.
975  */
976 void osc_inc_unstable_pages(struct ptlrpc_request *req)
977 {
978         struct ptlrpc_bulk_desc *desc = req->rq_bulk;
979         struct osc_brw_async_args *aa = (void *)&req->rq_async_args;
980         struct client_obd       *cli  = &req->rq_import->imp_obd->u.cli;
981         long                     page_count;
982
983         /* No unstable page tracking */
984         if (cli->cl_cache == NULL || !cli->cl_cache->ccc_unstable_check)
985                 return;
986
987         if (desc)
988                 page_count = desc->bd_iov_count;
989         else
990                 page_count = aa->aa_page_count;
991
992         add_unstable_page_accounting(desc, aa);
993         atomic_long_add(page_count, &cli->cl_unstable_count);
994         atomic_long_add(page_count, &cli->cl_cache->ccc_unstable_nr);
995
996         /* If the request has already been committed (i.e. brw_commit
997          * called via rq_commit_cb), we need to undo the unstable page
998          * increments we just performed because rq_commit_cb wont be
999          * called again. */
1000         spin_lock(&req->rq_lock);
1001         if (unlikely(req->rq_committed)) {
1002                 spin_unlock(&req->rq_lock);
1003
1004                 osc_dec_unstable_pages(req);
1005         } else {
1006                 req->rq_unstable = 1;
1007                 spin_unlock(&req->rq_lock);
1008         }
1009 }
1010
1011 /**
1012  * Check if it piggybacks SOFT_SYNC flag to OST from this OSC.
1013  * This function will be called by every BRW RPC so it's critical
1014  * to make this function fast.
1015  */
1016 bool osc_over_unstable_soft_limit(struct client_obd *cli)
1017 {
1018         long unstable_nr, osc_unstable_count;
1019
1020         /* Can't check cli->cl_unstable_count, therefore, no soft limit */
1021         if (cli->cl_cache == NULL || !cli->cl_cache->ccc_unstable_check)
1022                 return false;
1023
1024         osc_unstable_count = atomic_long_read(&cli->cl_unstable_count);
1025         unstable_nr = atomic_long_read(&cli->cl_cache->ccc_unstable_nr);
1026
1027         CDEBUG(D_CACHE,
1028                "%s: cli: %p unstable pages: %lu, osc unstable pages: %lu\n",
1029                cli_name(cli), cli, unstable_nr, osc_unstable_count);
1030
1031         /* If the LRU slots are in shortage - 25% remaining AND this OSC
1032          * has one full RPC window of unstable pages, it's a good chance
1033          * to piggyback a SOFT_SYNC flag.
1034          * Please notice that the OST won't take immediate response for the
1035          * SOFT_SYNC request so active OSCs will have more chance to carry
1036          * the flag, this is reasonable. */
1037         return unstable_nr > cli->cl_cache->ccc_lru_max >> 2 &&
1038                osc_unstable_count > cli->cl_max_pages_per_rpc *
1039                                     cli->cl_max_rpcs_in_flight;
1040 }
1041
1042 /**
1043  * Return how many LRU pages in the cache of all OSC devices
1044  *
1045  * \retval      return # of cached LRU pages times reclaimation tendency
1046  * \retval      SHRINK_STOP if it cannot do any scanning in this time
1047  */
1048 unsigned long osc_cache_shrink_count(struct shrinker *sk,
1049                                      struct shrink_control *sc)
1050 {
1051         struct client_obd *cli;
1052         unsigned long cached = 0;
1053
1054         spin_lock(&osc_shrink_lock);
1055         list_for_each_entry(cli, &osc_shrink_list, cl_shrink_list)
1056                 cached += atomic_long_read(&cli->cl_lru_in_list);
1057         spin_unlock(&osc_shrink_lock);
1058
1059         return (cached  * sysctl_vfs_cache_pressure) / 100;
1060 }
1061
1062 /**
1063  * Scan and try to reclaim sc->nr_to_scan cached LRU pages
1064  *
1065  * \retval      number of cached LRU pages reclaimed
1066  * \retval      SHRINK_STOP if it cannot do any scanning in this time
1067  *
1068  * Linux kernel will loop calling this shrinker scan routine with
1069  * sc->nr_to_scan = SHRINK_BATCH(128 for now) until kernel got enough memory.
1070  *
1071  * If sc->nr_to_scan is 0, the VM is querying the cache size, we don't need
1072  * to scan and try to reclaim LRU pages, just return 0 and
1073  * osc_cache_shrink_count() will report the LRU page number.
1074  */
1075 unsigned long osc_cache_shrink_scan(struct shrinker *sk,
1076                                     struct shrink_control *sc)
1077 {
1078         struct client_obd *cli;
1079         struct client_obd *stop_anchor = NULL;
1080         struct lu_env *env;
1081         long shrank = 0;
1082         int rc;
1083         __u16 refcheck;
1084
1085         if (sc->nr_to_scan == 0)
1086                 return 0;
1087
1088         if (!(sc->gfp_mask & __GFP_FS))
1089                 return SHRINK_STOP;
1090
1091         env = cl_env_get(&refcheck);
1092         if (IS_ERR(env))
1093                 return SHRINK_STOP;
1094
1095         spin_lock(&osc_shrink_lock);
1096         while (!list_empty(&osc_shrink_list)) {
1097                 cli = list_entry(osc_shrink_list.next, struct client_obd,
1098                                  cl_shrink_list);
1099
1100                 if (stop_anchor == NULL)
1101                         stop_anchor = cli;
1102                 else if (cli == stop_anchor)
1103                         break;
1104
1105                 list_move_tail(&cli->cl_shrink_list, &osc_shrink_list);
1106                 spin_unlock(&osc_shrink_lock);
1107
1108                 /* shrink no more than max_pages_per_rpc for an OSC */
1109                 rc = osc_lru_shrink(env, cli, (sc->nr_to_scan - shrank) >
1110                                     cli->cl_max_pages_per_rpc ?
1111                                     cli->cl_max_pages_per_rpc :
1112                                     sc->nr_to_scan - shrank, true);
1113                 if (rc > 0)
1114                         shrank += rc;
1115
1116                 if (shrank >= sc->nr_to_scan)
1117                         goto out;
1118
1119                 spin_lock(&osc_shrink_lock);
1120         }
1121         spin_unlock(&osc_shrink_lock);
1122
1123 out:
1124         cl_env_put(env, &refcheck);
1125
1126         return shrank;
1127 }
1128
1129 /** @} osc */