4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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,
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10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
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13 * General Public License version 2 for more details (a copy is included
14 * in the LICENSE file that accompanied this code).
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18 * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
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21 * CA 95054 USA or visit www.sun.com if you need additional information or
27 * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
28 * Use is subject to license terms.
30 * Copyright (c) 2011, 2014, Intel Corporation.
33 * This file is part of Lustre, http://www.lustre.org/
34 * Lustre is a trademark of Sun Microsystems, Inc.
36 * Implementation of cl_page for OSC layer.
38 * Author: Nikita Danilov <nikita.danilov@sun.com>
39 * Author: Jinshan Xiong <jinshan.xiong@intel.com>
42 #define DEBUG_SUBSYSTEM S_OSC
44 #include "osc_cl_internal.h"
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_alloc(const struct lu_env *env, struct client_obd *cli,
49 struct osc_page *opg);
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.
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)
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;
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);
85 flags = LDLM_FL_TEST_LOCK | LDLM_FL_BLOCK_GRANTED;
87 flags |= LDLM_FL_CBPENDING;
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);
97 * Checks an invariant that a page in the cache is covered by a lock, as
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)
104 struct cl_object_header *hdr;
105 struct cl_lock *scan;
106 struct cl_page *page;
107 struct cl_lock_descr *descr;
110 LINVRNT(!opg->ops_temp);
112 page = opg->ops_cl.cpl_page;
113 if (page->cp_owner != NULL &&
114 cl_io_top(page->cp_owner)->ci_lockreq == CILR_NEVER)
116 * If IO is done without locks (liblustre, or lloop), lock is
121 /* otherwise check for a DLM lock */
122 result = osc_page_is_dlocked(env, opg, mode, 1, unref);
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) {
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().
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;
143 olck = osc_lock_at(scan);
144 result = osc_lock_is_lockless(olck);
148 spin_unlock(&hdr->coh_lock_guard);
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)
161 /*****************************************************************************
166 static void osc_page_transfer_get(struct osc_page *opg, const char *label)
168 struct cl_page *page = opg->ops_cl.cpl_page;
170 LASSERT(!opg->ops_transfer_pinned);
172 lu_ref_add_atomic(&page->cp_reference, label, page);
173 opg->ops_transfer_pinned = 1;
176 static void osc_page_transfer_put(const struct lu_env *env,
177 struct osc_page *opg)
179 struct cl_page *page = opg->ops_cl.cpl_page;
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);
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()).
193 static void osc_page_transfer_add(const struct lu_env *env,
194 struct osc_page *opg, enum cl_req_type crt)
196 struct osc_object *obj = cl2osc(opg->ops_cl.cpl_obj);
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);
203 int osc_page_cache_add(const struct lu_env *env,
204 const struct cl_page_slice *slice, struct cl_io *io)
206 struct osc_page *opg = cl2osc_page(slice);
210 LINVRNT(osc_page_protected(env, opg, CLM_WRITE, 0));
212 osc_page_transfer_get(opg, "transfer\0cache");
213 result = osc_queue_async_io(env, io, opg);
215 osc_page_transfer_put(env, opg);
217 osc_page_transfer_add(env, opg, CRT_WRITE);
222 void osc_index2policy(union ldlm_policy_data *policy,
223 const struct cl_object *obj, pgoff_t start, pgoff_t end)
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;
230 static const char *osc_list(struct list_head *head)
232 return list_empty(head) ? "-" : "+";
235 static inline cfs_time_t osc_submit_duration(struct osc_page *opg)
237 if (opg->ops_submit_time == 0)
240 return (cfs_time_current() - opg->ops_submit_time);
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)
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;
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 > "
256 "4< %d %d %d %lu %s | %s %s %s %s > "
257 "5< %s %s %s %s | %d %s | %d %s %s>\n",
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),
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,
269 opg->ops_transfer_pinned,
270 osc_submit_duration(opg), opg->ops_srvlock,
272 cli->cl_r_in_flight, cli->cl_w_in_flight,
273 cli->cl_max_rpcs_in_flight,
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),
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));
292 static void osc_page_delete(const struct lu_env *env,
293 const struct cl_page_slice *slice)
295 struct osc_page *opg = cl2osc_page(slice);
296 struct osc_object *obj = cl2osc(opg->ops_cl.cpl_obj);
299 LINVRNT(opg->ops_temp || osc_page_protected(env, opg, CLM_READ, 1));
302 CDEBUG(D_TRACE, "%p\n", opg);
303 osc_page_transfer_put(env, opg);
304 rc = osc_teardown_async_page(env, obj, opg);
306 CL_PAGE_DEBUG(D_ERROR, env, slice->cpl_page,
307 "Trying to teardown failed: %d\n", rc);
311 osc_lru_del(osc_cli(obj), opg);
313 if (slice->cpl_page->cp_type == CPT_CACHEABLE) {
316 spin_lock(&obj->oo_tree_lock);
317 value = radix_tree_delete(&obj->oo_tree, osc_index(opg));
320 spin_unlock(&obj->oo_tree_lock);
322 LASSERT(ergo(value != NULL, value == opg));
328 static void osc_page_clip(const struct lu_env *env,
329 const struct cl_page_slice *slice,
332 struct osc_page *opg = cl2osc_page(slice);
333 struct osc_async_page *oap = &opg->ops_oap;
335 LINVRNT(osc_page_protected(env, opg, CLM_READ, 0));
337 opg->ops_from = from;
339 spin_lock(&oap->oap_lock);
340 oap->oap_async_flags |= ASYNC_COUNT_STABLE;
341 spin_unlock(&oap->oap_lock);
344 static int osc_page_cancel(const struct lu_env *env,
345 const struct cl_page_slice *slice)
347 struct osc_page *opg = cl2osc_page(slice);
350 LINVRNT(osc_page_protected(env, opg, CLM_READ, 0));
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));
361 static int osc_page_flush(const struct lu_env *env,
362 const struct cl_page_slice *slice,
365 struct osc_page *opg = cl2osc_page(slice);
368 rc = osc_flush_async_page(env, io, opg);
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
380 int osc_page_init(const struct lu_env *env, struct cl_object *obj,
381 struct cl_page *page, pgoff_t index)
383 struct osc_object *osc = cl2osc(obj);
384 struct osc_page *opg = cl_object_page_slice(obj, page);
388 opg->ops_to = PAGE_CACHE_SIZE;
390 result = osc_prep_async_page(osc, opg, page->cp_vmpage,
391 cl_offset(obj, index));
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,
399 * Cannot assert osc_page_protected() here as read-ahead
400 * creates temporary pages outside of a lock.
402 #ifdef CONFIG_LUSTRE_DEBUG_EXPENSIVE_CHECK
403 opg->ops_temp = !osc_page_protected(env, opg, CLM_READ, 1);
405 INIT_LIST_HEAD(&opg->ops_lru);
407 /* reserve an LRU space for this page */
408 if (page->cp_type == CPT_CACHEABLE && result == 0) {
409 result = osc_lru_alloc(env, osc_cli(osc), opg);
411 spin_lock(&osc->oo_tree_lock);
412 result = radix_tree_insert(&osc->oo_tree, index, opg);
415 spin_unlock(&osc->oo_tree_lock);
416 LASSERT(result == 0);
424 * Helper function called by osc_io_submit() for every page in an immediate
425 * transfer (i.e., transferred synchronously).
427 void osc_page_submit(const struct lu_env *env, struct osc_page *opg,
428 enum cl_req_type crt, int brw_flags)
430 struct osc_async_page *oap = &opg->ops_oap;
431 struct osc_object *obj = oap->oap_obj;
433 LINVRNT(osc_page_protected(env, opg,
434 crt == CRT_WRITE ? CLM_WRITE : CLM_READ, 1));
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);
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;
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;
452 opg->ops_submit_time = cfs_time_current();
453 osc_page_transfer_get(opg, "transfer\0imm");
454 osc_page_transfer_add(env, opg, crt);
457 /* --------------- LRU page management ------------------ */
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
468 static DECLARE_WAIT_QUEUE_HEAD(osc_lru_waitq);
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.
474 static inline int lru_shrink_min(struct client_obd *cli)
476 return cli->cl_max_pages_per_rpc * 2;
480 * free this number at most otherwise it will take too long time to finsih.
482 static inline int lru_shrink_max(struct client_obd *cli)
484 return cli->cl_max_pages_per_rpc * cli->cl_max_rpcs_in_flight;
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.
492 * Return how many LRU pages should be freed.
494 static int osc_cache_too_much(struct client_obd *cli)
496 struct cl_client_cache *cache = cli->cl_cache;
497 long pages = atomic_long_read(&cli->cl_lru_in_list);
498 unsigned long budget;
500 LASSERT(cache != NULL);
501 budget = cache->ccc_lru_max / (atomic_read(&cache->ccc_users) - 2);
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) {
507 return lru_shrink_max(cli);
508 else if (pages >= budget / 2)
509 return lru_shrink_min(cli);
511 int duration = cfs_time_current_sec() - cli->cl_lru_last_used;
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);
521 int lru_queue_work(const struct lu_env *env, void *data)
523 struct client_obd *cli = data;
526 CDEBUG(D_CACHE, "%s: run LRU work for client obd\n", cli_name(cli));
527 count = osc_cache_too_much(cli);
529 int rc = osc_lru_shrink(env, cli, count, false);
531 CDEBUG(D_CACHE, "%s: shrank %d/%d pages from client obd\n",
532 cli_name(cli), rc, count);
534 CDEBUG(D_CACHE, "%s: queue again\n", cli_name(cli));
535 ptlrpcd_queue_work(cli->cl_lru_work);
542 void osc_lru_add_batch(struct client_obd *cli, struct list_head *plist)
544 struct list_head lru = LIST_HEAD_INIT(lru);
545 struct osc_async_page *oap;
548 list_for_each_entry(oap, plist, oap_pending_item) {
549 struct osc_page *opg = oap2osc_page(oap);
551 if (!opg->ops_in_lru)
555 LASSERT(list_empty(&opg->ops_lru));
556 list_add(&opg->ops_lru, &lru);
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);
567 if (waitqueue_active(&osc_lru_waitq))
568 (void)ptlrpcd_queue_work(cli->cl_lru_work);
572 static void __osc_lru_del(struct client_obd *cli, struct osc_page *opg)
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);
580 * Page is being destroyed. The page may be not in LRU list, if the transfer
581 * has never finished(error occurred).
583 static void osc_lru_del(struct client_obd *cli, struct osc_page *opg)
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);
590 LASSERT(atomic_long_read(&cli->cl_lru_busy) > 0);
591 atomic_long_dec(&cli->cl_lru_busy);
593 spin_unlock(&cli->cl_lru_list_lock);
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);
603 wake_up(&osc_lru_waitq);
605 LASSERT(list_empty(&opg->ops_lru));
610 * Delete page from LRUlist for redirty.
612 static void osc_lru_use(struct client_obd *cli, struct osc_page *opg)
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);
624 static void discard_pagevec(const struct lu_env *env, struct cl_io *io,
625 struct cl_page **pvec, int max_index)
629 for (i = 0; i < max_index; i++) {
630 struct cl_page *page = pvec[i];
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);
643 * Check if a cl_page can be released, i.e, it's not being used.
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.
649 static inline bool lru_page_busy(struct client_obd *cli, struct cl_page *page)
651 if (cl_page_in_use_noref(page))
654 if (cli->cl_cache->ccc_unstable_check) {
655 struct page *vmpage = cl_page_vmpage(page);
657 /* vmpage have two known users: cl_page and VM page cache */
658 if (page_count(vmpage) - page_mapcount(vmpage) > 2)
665 * Drop @target of pages from LRU at most.
667 long osc_lru_shrink(const struct lu_env *env, struct client_obd *cli,
668 long target, bool force)
671 struct cl_object *clobj = NULL;
672 struct cl_page **pvec;
673 struct osc_page *opg;
680 LASSERT(atomic_long_read(&cli->cl_lru_in_list) >= 0);
681 if (atomic_long_read(&cli->cl_lru_in_list) == 0 || target <= 0)
684 CDEBUG(D_CACHE, "%s: shrinkers: %d, force: %d\n",
685 cli_name(cli), atomic_read(&cli->cl_lru_shrinkers), force);
687 if (atomic_read(&cli->cl_lru_shrinkers) > 0)
690 if (atomic_inc_return(&cli->cl_lru_shrinkers) > 1) {
691 atomic_dec(&cli->cl_lru_shrinkers);
695 atomic_inc(&cli->cl_lru_shrinkers);
698 pvec = (struct cl_page **)osc_env_info(env)->oti_pvec;
699 io = &osc_env_info(env)->oti_io;
701 spin_lock(&cli->cl_lru_list_lock);
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;
709 if (!force && atomic_read(&cli->cl_lru_shrinkers) > 1)
715 opg = list_entry(cli->cl_lru_list.next, struct osc_page,
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);
723 LASSERT(page->cp_obj != NULL);
724 if (clobj != page->cp_obj) {
725 struct cl_object *tmp = page->cp_obj;
728 spin_unlock(&cli->cl_lru_list_lock);
731 discard_pagevec(env, io, pvec, index);
735 cl_object_put(env, clobj);
741 io->ci_ignore_layout = 1;
742 rc = cl_io_init(env, io, CIT_MISC, clobj);
744 spin_lock(&cli->cl_lru_list_lock);
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
757 __osc_lru_del(cli, opg);
758 opg->ops_in_lru = 0; /* will be discarded */
763 cl_page_disown(env, io, page);
768 list_move_tail(&opg->ops_lru, &cli->cl_lru_list);
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);
779 spin_lock(&cli->cl_lru_list_lock);
782 if (++count >= target)
785 spin_unlock(&cli->cl_lru_list_lock);
788 discard_pagevec(env, io, pvec, index);
791 cl_object_put(env, clobj);
794 atomic_dec(&cli->cl_lru_shrinkers);
796 atomic_long_add(count, cli->cl_lru_left);
797 wake_up_all(&osc_lru_waitq);
799 RETURN(count > 0 ? count : rc);
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
808 static long osc_lru_reclaim(struct client_obd *cli, unsigned long npages)
810 struct cl_env_nest nest;
812 struct cl_client_cache *cache = cli->cl_cache;
817 LASSERT(cache != NULL);
819 env = cl_env_nested_get(&nest);
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);
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);
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);
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));
846 cache->ccc_lru_shrinkers++;
847 list_move_tail(&cli->cl_lru_osc, &cache->ccc_lru);
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,
854 CDEBUG(D_CACHE, "%s: cli %p LRU pages: %ld, busy: %ld.\n",
856 atomic_long_read(&cli->cl_lru_in_list),
857 atomic_long_read(&cli->cl_lru_busy));
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);
863 rc = osc_lru_shrink(env, cli, npages, true);
864 spin_lock(&cache->ccc_lru_lock);
871 spin_unlock(&cache->ccc_lru_lock);
874 cl_env_nested_put(&nest, env);
875 CDEBUG(D_CACHE, "%s: cli %p freed %ld pages.\n",
876 cli_name(cli), cli, rc);
881 * osc_lru_alloc() is called to allocate an LRU slot for a cl_page.
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.
887 static int osc_lru_alloc(const struct lu_env *env, struct client_obd *cli,
888 struct osc_page *opg)
890 struct l_wait_info lwi = LWI_INTR(LWI_ON_SIGNAL_NOOP, NULL);
891 struct osc_io *oio = osc_env_io(env);
895 if (cli->cl_cache == NULL) /* shall not be in LRU */
898 if (oio->oi_lru_reserved > 0) {
899 --oio->oi_lru_reserved;
903 LASSERT(atomic_long_read(cli->cl_lru_left) >= 0);
904 while (!atomic_long_add_unless(cli->cl_lru_left, -1, 0)) {
905 /* run out of LRU spaces, try to drop some by itself */
906 rc = osc_lru_reclaim(cli, 1);
913 rc = l_wait_event(osc_lru_waitq,
914 atomic_long_read(cli->cl_lru_left) > 0,
922 atomic_long_inc(&cli->cl_lru_busy);
931 * osc_lru_reserve() is called to reserve enough LRU slots for I/O.
933 * The benefit of doing this is to reduce contention against atomic counter
934 * cl_lru_left by changing it from per-page access to per-IO access.
936 unsigned long osc_lru_reserve(struct client_obd *cli, unsigned long npages)
938 unsigned long reserved = 0;
939 unsigned long max_pages;
942 /* reserve a full RPC window at most to avoid that a thread accidentally
943 * consumes too many LRU slots */
944 max_pages = cli->cl_max_pages_per_rpc * cli->cl_max_rpcs_in_flight;
945 if (npages > max_pages)
948 c = atomic_long_read(cli->cl_lru_left);
949 if (c < npages && osc_lru_reclaim(cli, npages) > 0)
950 c = atomic_long_read(cli->cl_lru_left);
951 while (c >= npages) {
952 if (c == atomic_long_cmpxchg(cli->cl_lru_left, c, c - npages)) {
956 c = atomic_long_read(cli->cl_lru_left);
958 if (atomic_long_read(cli->cl_lru_left) < max_pages) {
959 /* If there aren't enough pages in the per-OSC LRU then
960 * wake up the LRU thread to try and clear out space, so
961 * we don't block if pages are being dirtied quickly. */
962 CDEBUG(D_CACHE, "%s: queue LRU, left: %lu/%ld.\n",
963 cli_name(cli), atomic_long_read(cli->cl_lru_left),
965 (void)ptlrpcd_queue_work(cli->cl_lru_work);
972 * osc_lru_unreserve() is called to unreserve LRU slots.
974 * LRU slots reserved by osc_lru_reserve() may have entries left due to several
975 * reasons such as page already existing or I/O error. Those reserved slots
976 * should be freed by calling this function.
978 void osc_lru_unreserve(struct client_obd *cli, unsigned long npages)
980 atomic_long_add(npages, cli->cl_lru_left);
981 wake_up_all(&osc_lru_waitq);
985 * Atomic operations are expensive. We accumulate the accounting for the
986 * same page zone to get better performance.
987 * In practice this can work pretty good because the pages in the same RPC
988 * are likely from the same page zone.
990 static inline void unstable_page_accounting(struct ptlrpc_bulk_desc *desc,
993 int page_count = desc->bd_iov_count;
998 LASSERT(ptlrpc_is_bulk_desc_kiov(desc->bd_type));
1000 for (i = 0; i < page_count; i++) {
1001 void *pz = page_zone(BD_GET_KIOV(desc, i).kiov_page);
1003 if (likely(pz == zone)) {
1009 mod_zone_page_state(zone, NR_UNSTABLE_NFS,
1017 mod_zone_page_state(zone, NR_UNSTABLE_NFS, factor * count);
1020 static inline void add_unstable_page_accounting(struct ptlrpc_bulk_desc *desc)
1022 unstable_page_accounting(desc, 1);
1025 static inline void dec_unstable_page_accounting(struct ptlrpc_bulk_desc *desc)
1027 unstable_page_accounting(desc, -1);
1031 * Performs "unstable" page accounting. This function balances the
1032 * increment operations performed in osc_inc_unstable_pages. It is
1033 * registered as the RPC request callback, and is executed when the
1034 * bulk RPC is committed on the server. Thus at this point, the pages
1035 * involved in the bulk transfer are no longer considered unstable.
1037 * If this function is called, the request should have been committed
1038 * or req:rq_unstable must have been set; it implies that the unstable
1039 * statistic have been added.
1041 void osc_dec_unstable_pages(struct ptlrpc_request *req)
1043 struct ptlrpc_bulk_desc *desc = req->rq_bulk;
1044 struct client_obd *cli = &req->rq_import->imp_obd->u.cli;
1045 int page_count = desc->bd_iov_count;
1046 long unstable_count;
1048 LASSERT(page_count >= 0);
1049 dec_unstable_page_accounting(desc);
1051 unstable_count = atomic_long_sub_return(page_count,
1052 &cli->cl_unstable_count);
1053 LASSERT(unstable_count >= 0);
1055 unstable_count = atomic_long_sub_return(page_count,
1056 &cli->cl_cache->ccc_unstable_nr);
1057 LASSERT(unstable_count >= 0);
1058 if (unstable_count == 0)
1059 wake_up_all(&cli->cl_cache->ccc_unstable_waitq);
1061 if (waitqueue_active(&osc_lru_waitq))
1062 (void)ptlrpcd_queue_work(cli->cl_lru_work);
1066 * "unstable" page accounting. See: osc_dec_unstable_pages.
1068 void osc_inc_unstable_pages(struct ptlrpc_request *req)
1070 struct ptlrpc_bulk_desc *desc = req->rq_bulk;
1071 struct client_obd *cli = &req->rq_import->imp_obd->u.cli;
1072 long page_count = desc->bd_iov_count;
1074 /* No unstable page tracking */
1075 if (cli->cl_cache == NULL || !cli->cl_cache->ccc_unstable_check)
1078 add_unstable_page_accounting(desc);
1079 atomic_long_add(page_count, &cli->cl_unstable_count);
1080 atomic_long_add(page_count, &cli->cl_cache->ccc_unstable_nr);
1082 /* If the request has already been committed (i.e. brw_commit
1083 * called via rq_commit_cb), we need to undo the unstable page
1084 * increments we just performed because rq_commit_cb wont be
1086 spin_lock(&req->rq_lock);
1087 if (unlikely(req->rq_committed)) {
1088 spin_unlock(&req->rq_lock);
1090 osc_dec_unstable_pages(req);
1092 req->rq_unstable = 1;
1093 spin_unlock(&req->rq_lock);
1098 * Check if it piggybacks SOFT_SYNC flag to OST from this OSC.
1099 * This function will be called by every BRW RPC so it's critical
1100 * to make this function fast.
1102 bool osc_over_unstable_soft_limit(struct client_obd *cli)
1104 long unstable_nr, osc_unstable_count;
1106 /* Can't check cli->cl_unstable_count, therefore, no soft limit */
1107 if (cli->cl_cache == NULL || !cli->cl_cache->ccc_unstable_check)
1110 osc_unstable_count = atomic_long_read(&cli->cl_unstable_count);
1111 unstable_nr = atomic_long_read(&cli->cl_cache->ccc_unstable_nr);
1114 "%s: cli: %p unstable pages: %lu, osc unstable pages: %lu\n",
1115 cli_name(cli), cli, unstable_nr, osc_unstable_count);
1117 /* If the LRU slots are in shortage - 25% remaining AND this OSC
1118 * has one full RPC window of unstable pages, it's a good chance
1119 * to piggyback a SOFT_SYNC flag.
1120 * Please notice that the OST won't take immediate response for the
1121 * SOFT_SYNC request so active OSCs will have more chance to carry
1122 * the flag, this is reasonable. */
1123 return unstable_nr > cli->cl_cache->ccc_lru_max >> 2 &&
1124 osc_unstable_count > cli->cl_max_pages_per_rpc *
1125 cli->cl_max_rpcs_in_flight;