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1// SPDX-License-Identifier: GPL-2.02/*3 * Interface for controlling IO bandwidth on a request queue4 *5 * Copyright (C) 2010 Vivek Goyal <vgoyal@redhat.com>6 */7 8#include <linux/module.h>9#include <linux/slab.h>10#include <linux/blkdev.h>11#include <linux/bio.h>12#include <linux/blktrace_api.h>13#include "blk.h"14#include "blk-cgroup-rwstat.h"15#include "blk-stat.h"16#include "blk-throttle.h"17 18/* Max dispatch from a group in 1 round */19#define THROTL_GRP_QUANTUM 820 21/* Total max dispatch from all groups in one round */22#define THROTL_QUANTUM 3223 24/* Throttling is performed over a slice and after that slice is renewed */25#define DFL_THROTL_SLICE_HD (HZ / 10)26#define DFL_THROTL_SLICE_SSD (HZ / 50)27#define MAX_THROTL_SLICE (HZ)28 29/* A workqueue to queue throttle related work */30static struct workqueue_struct *kthrotld_workqueue;31 32#define rb_entry_tg(node) rb_entry((node), struct throtl_grp, rb_node)33 34struct throtl_data35{36 /* service tree for active throtl groups */37 struct throtl_service_queue service_queue;38 39 struct request_queue *queue;40 41 /* Total Number of queued bios on READ and WRITE lists */42 unsigned int nr_queued[2];43 44 unsigned int throtl_slice;45 46 /* Work for dispatching throttled bios */47 struct work_struct dispatch_work;48 49 bool track_bio_latency;50};51 52static void throtl_pending_timer_fn(struct timer_list *t);53 54static inline struct blkcg_gq *tg_to_blkg(struct throtl_grp *tg)55{56 return pd_to_blkg(&tg->pd);57}58 59/**60 * sq_to_tg - return the throl_grp the specified service queue belongs to61 * @sq: the throtl_service_queue of interest62 *63 * Return the throtl_grp @sq belongs to. If @sq is the top-level one64 * embedded in throtl_data, %NULL is returned.65 */66static struct throtl_grp *sq_to_tg(struct throtl_service_queue *sq)67{68 if (sq && sq->parent_sq)69 return container_of(sq, struct throtl_grp, service_queue);70 else71 return NULL;72}73 74/**75 * sq_to_td - return throtl_data the specified service queue belongs to76 * @sq: the throtl_service_queue of interest77 *78 * A service_queue can be embedded in either a throtl_grp or throtl_data.79 * Determine the associated throtl_data accordingly and return it.80 */81static struct throtl_data *sq_to_td(struct throtl_service_queue *sq)82{83 struct throtl_grp *tg = sq_to_tg(sq);84 85 if (tg)86 return tg->td;87 else88 return container_of(sq, struct throtl_data, service_queue);89}90 91static uint64_t tg_bps_limit(struct throtl_grp *tg, int rw)92{93 struct blkcg_gq *blkg = tg_to_blkg(tg);94 95 if (cgroup_subsys_on_dfl(io_cgrp_subsys) && !blkg->parent)96 return U64_MAX;97 98 return tg->bps[rw];99}100 101static unsigned int tg_iops_limit(struct throtl_grp *tg, int rw)102{103 struct blkcg_gq *blkg = tg_to_blkg(tg);104 105 if (cgroup_subsys_on_dfl(io_cgrp_subsys) && !blkg->parent)106 return UINT_MAX;107 108 return tg->iops[rw];109}110 111/**112 * throtl_log - log debug message via blktrace113 * @sq: the service_queue being reported114 * @fmt: printf format string115 * @args: printf args116 *117 * The messages are prefixed with "throtl BLKG_NAME" if @sq belongs to a118 * throtl_grp; otherwise, just "throtl".119 */120#define throtl_log(sq, fmt, args...) do { \121 struct throtl_grp *__tg = sq_to_tg((sq)); \122 struct throtl_data *__td = sq_to_td((sq)); \123 \124 (void)__td; \125 if (likely(!blk_trace_note_message_enabled(__td->queue))) \126 break; \127 if ((__tg)) { \128 blk_add_cgroup_trace_msg(__td->queue, \129 &tg_to_blkg(__tg)->blkcg->css, "throtl " fmt, ##args);\130 } else { \131 blk_add_trace_msg(__td->queue, "throtl " fmt, ##args); \132 } \133} while (0)134 135static inline unsigned int throtl_bio_data_size(struct bio *bio)136{137 /* assume it's one sector */138 if (unlikely(bio_op(bio) == REQ_OP_DISCARD))139 return 512;140 return bio->bi_iter.bi_size;141}142 143static void throtl_qnode_init(struct throtl_qnode *qn, struct throtl_grp *tg)144{145 INIT_LIST_HEAD(&qn->node);146 bio_list_init(&qn->bios);147 qn->tg = tg;148}149 150/**151 * throtl_qnode_add_bio - add a bio to a throtl_qnode and activate it152 * @bio: bio being added153 * @qn: qnode to add bio to154 * @queued: the service_queue->queued[] list @qn belongs to155 *156 * Add @bio to @qn and put @qn on @queued if it's not already on.157 * @qn->tg's reference count is bumped when @qn is activated. See the158 * comment on top of throtl_qnode definition for details.159 */160static void throtl_qnode_add_bio(struct bio *bio, struct throtl_qnode *qn,161 struct list_head *queued)162{163 bio_list_add(&qn->bios, bio);164 if (list_empty(&qn->node)) {165 list_add_tail(&qn->node, queued);166 blkg_get(tg_to_blkg(qn->tg));167 }168}169 170/**171 * throtl_peek_queued - peek the first bio on a qnode list172 * @queued: the qnode list to peek173 */174static struct bio *throtl_peek_queued(struct list_head *queued)175{176 struct throtl_qnode *qn;177 struct bio *bio;178 179 if (list_empty(queued))180 return NULL;181 182 qn = list_first_entry(queued, struct throtl_qnode, node);183 bio = bio_list_peek(&qn->bios);184 WARN_ON_ONCE(!bio);185 return bio;186}187 188/**189 * throtl_pop_queued - pop the first bio form a qnode list190 * @queued: the qnode list to pop a bio from191 * @tg_to_put: optional out argument for throtl_grp to put192 *193 * Pop the first bio from the qnode list @queued. After popping, the first194 * qnode is removed from @queued if empty or moved to the end of @queued so195 * that the popping order is round-robin.196 *197 * When the first qnode is removed, its associated throtl_grp should be put198 * too. If @tg_to_put is NULL, this function automatically puts it;199 * otherwise, *@tg_to_put is set to the throtl_grp to put and the caller is200 * responsible for putting it.201 */202static struct bio *throtl_pop_queued(struct list_head *queued,203 struct throtl_grp **tg_to_put)204{205 struct throtl_qnode *qn;206 struct bio *bio;207 208 if (list_empty(queued))209 return NULL;210 211 qn = list_first_entry(queued, struct throtl_qnode, node);212 bio = bio_list_pop(&qn->bios);213 WARN_ON_ONCE(!bio);214 215 if (bio_list_empty(&qn->bios)) {216 list_del_init(&qn->node);217 if (tg_to_put)218 *tg_to_put = qn->tg;219 else220 blkg_put(tg_to_blkg(qn->tg));221 } else {222 list_move_tail(&qn->node, queued);223 }224 225 return bio;226}227 228/* init a service_queue, assumes the caller zeroed it */229static void throtl_service_queue_init(struct throtl_service_queue *sq)230{231 INIT_LIST_HEAD(&sq->queued[READ]);232 INIT_LIST_HEAD(&sq->queued[WRITE]);233 sq->pending_tree = RB_ROOT_CACHED;234 timer_setup(&sq->pending_timer, throtl_pending_timer_fn, 0);235}236 237static struct blkg_policy_data *throtl_pd_alloc(struct gendisk *disk,238 struct blkcg *blkcg, gfp_t gfp)239{240 struct throtl_grp *tg;241 int rw;242 243 tg = kzalloc_node(sizeof(*tg), gfp, disk->node_id);244 if (!tg)245 return NULL;246 247 if (blkg_rwstat_init(&tg->stat_bytes, gfp))248 goto err_free_tg;249 250 if (blkg_rwstat_init(&tg->stat_ios, gfp))251 goto err_exit_stat_bytes;252 253 throtl_service_queue_init(&tg->service_queue);254 255 for (rw = READ; rw <= WRITE; rw++) {256 throtl_qnode_init(&tg->qnode_on_self[rw], tg);257 throtl_qnode_init(&tg->qnode_on_parent[rw], tg);258 }259 260 RB_CLEAR_NODE(&tg->rb_node);261 tg->bps[READ] = U64_MAX;262 tg->bps[WRITE] = U64_MAX;263 tg->iops[READ] = UINT_MAX;264 tg->iops[WRITE] = UINT_MAX;265 266 return &tg->pd;267 268err_exit_stat_bytes:269 blkg_rwstat_exit(&tg->stat_bytes);270err_free_tg:271 kfree(tg);272 return NULL;273}274 275static void throtl_pd_init(struct blkg_policy_data *pd)276{277 struct throtl_grp *tg = pd_to_tg(pd);278 struct blkcg_gq *blkg = tg_to_blkg(tg);279 struct throtl_data *td = blkg->q->td;280 struct throtl_service_queue *sq = &tg->service_queue;281 282 /*283 * If on the default hierarchy, we switch to properly hierarchical284 * behavior where limits on a given throtl_grp are applied to the285 * whole subtree rather than just the group itself. e.g. If 16M286 * read_bps limit is set on a parent group, summary bps of287 * parent group and its subtree groups can't exceed 16M for the288 * device.289 *290 * If not on the default hierarchy, the broken flat hierarchy291 * behavior is retained where all throtl_grps are treated as if292 * they're all separate root groups right below throtl_data.293 * Limits of a group don't interact with limits of other groups294 * regardless of the position of the group in the hierarchy.295 */296 sq->parent_sq = &td->service_queue;297 if (cgroup_subsys_on_dfl(io_cgrp_subsys) && blkg->parent)298 sq->parent_sq = &blkg_to_tg(blkg->parent)->service_queue;299 tg->td = td;300}301 302/*303 * Set has_rules[] if @tg or any of its parents have limits configured.304 * This doesn't require walking up to the top of the hierarchy as the305 * parent's has_rules[] is guaranteed to be correct.306 */307static void tg_update_has_rules(struct throtl_grp *tg)308{309 struct throtl_grp *parent_tg = sq_to_tg(tg->service_queue.parent_sq);310 int rw;311 312 for (rw = READ; rw <= WRITE; rw++) {313 tg->has_rules_iops[rw] =314 (parent_tg && parent_tg->has_rules_iops[rw]) ||315 tg_iops_limit(tg, rw) != UINT_MAX;316 tg->has_rules_bps[rw] =317 (parent_tg && parent_tg->has_rules_bps[rw]) ||318 tg_bps_limit(tg, rw) != U64_MAX;319 }320}321 322static void throtl_pd_online(struct blkg_policy_data *pd)323{324 struct throtl_grp *tg = pd_to_tg(pd);325 /*326 * We don't want new groups to escape the limits of its ancestors.327 * Update has_rules[] after a new group is brought online.328 */329 tg_update_has_rules(tg);330}331 332static void throtl_pd_free(struct blkg_policy_data *pd)333{334 struct throtl_grp *tg = pd_to_tg(pd);335 336 del_timer_sync(&tg->service_queue.pending_timer);337 blkg_rwstat_exit(&tg->stat_bytes);338 blkg_rwstat_exit(&tg->stat_ios);339 kfree(tg);340}341 342static struct throtl_grp *343throtl_rb_first(struct throtl_service_queue *parent_sq)344{345 struct rb_node *n;346 347 n = rb_first_cached(&parent_sq->pending_tree);348 WARN_ON_ONCE(!n);349 if (!n)350 return NULL;351 return rb_entry_tg(n);352}353 354static void throtl_rb_erase(struct rb_node *n,355 struct throtl_service_queue *parent_sq)356{357 rb_erase_cached(n, &parent_sq->pending_tree);358 RB_CLEAR_NODE(n);359}360 361static void update_min_dispatch_time(struct throtl_service_queue *parent_sq)362{363 struct throtl_grp *tg;364 365 tg = throtl_rb_first(parent_sq);366 if (!tg)367 return;368 369 parent_sq->first_pending_disptime = tg->disptime;370}371 372static void tg_service_queue_add(struct throtl_grp *tg)373{374 struct throtl_service_queue *parent_sq = tg->service_queue.parent_sq;375 struct rb_node **node = &parent_sq->pending_tree.rb_root.rb_node;376 struct rb_node *parent = NULL;377 struct throtl_grp *__tg;378 unsigned long key = tg->disptime;379 bool leftmost = true;380 381 while (*node != NULL) {382 parent = *node;383 __tg = rb_entry_tg(parent);384 385 if (time_before(key, __tg->disptime))386 node = &parent->rb_left;387 else {388 node = &parent->rb_right;389 leftmost = false;390 }391 }392 393 rb_link_node(&tg->rb_node, parent, node);394 rb_insert_color_cached(&tg->rb_node, &parent_sq->pending_tree,395 leftmost);396}397 398static void throtl_enqueue_tg(struct throtl_grp *tg)399{400 if (!(tg->flags & THROTL_TG_PENDING)) {401 tg_service_queue_add(tg);402 tg->flags |= THROTL_TG_PENDING;403 tg->service_queue.parent_sq->nr_pending++;404 }405}406 407static void throtl_dequeue_tg(struct throtl_grp *tg)408{409 if (tg->flags & THROTL_TG_PENDING) {410 struct throtl_service_queue *parent_sq =411 tg->service_queue.parent_sq;412 413 throtl_rb_erase(&tg->rb_node, parent_sq);414 --parent_sq->nr_pending;415 tg->flags &= ~THROTL_TG_PENDING;416 }417}418 419/* Call with queue lock held */420static void throtl_schedule_pending_timer(struct throtl_service_queue *sq,421 unsigned long expires)422{423 unsigned long max_expire = jiffies + 8 * sq_to_td(sq)->throtl_slice;424 425 /*426 * Since we are adjusting the throttle limit dynamically, the sleep427 * time calculated according to previous limit might be invalid. It's428 * possible the cgroup sleep time is very long and no other cgroups429 * have IO running so notify the limit changes. Make sure the cgroup430 * doesn't sleep too long to avoid the missed notification.431 */432 if (time_after(expires, max_expire))433 expires = max_expire;434 mod_timer(&sq->pending_timer, expires);435 throtl_log(sq, "schedule timer. delay=%lu jiffies=%lu",436 expires - jiffies, jiffies);437}438 439/**440 * throtl_schedule_next_dispatch - schedule the next dispatch cycle441 * @sq: the service_queue to schedule dispatch for442 * @force: force scheduling443 *444 * Arm @sq->pending_timer so that the next dispatch cycle starts on the445 * dispatch time of the first pending child. Returns %true if either timer446 * is armed or there's no pending child left. %false if the current447 * dispatch window is still open and the caller should continue448 * dispatching.449 *450 * If @force is %true, the dispatch timer is always scheduled and this451 * function is guaranteed to return %true. This is to be used when the452 * caller can't dispatch itself and needs to invoke pending_timer453 * unconditionally. Note that forced scheduling is likely to induce short454 * delay before dispatch starts even if @sq->first_pending_disptime is not455 * in the future and thus shouldn't be used in hot paths.456 */457static bool throtl_schedule_next_dispatch(struct throtl_service_queue *sq,458 bool force)459{460 /* any pending children left? */461 if (!sq->nr_pending)462 return true;463 464 update_min_dispatch_time(sq);465 466 /* is the next dispatch time in the future? */467 if (force || time_after(sq->first_pending_disptime, jiffies)) {468 throtl_schedule_pending_timer(sq, sq->first_pending_disptime);469 return true;470 }471 472 /* tell the caller to continue dispatching */473 return false;474}475 476static inline void throtl_start_new_slice_with_credit(struct throtl_grp *tg,477 bool rw, unsigned long start)478{479 tg->bytes_disp[rw] = 0;480 tg->io_disp[rw] = 0;481 tg->carryover_bytes[rw] = 0;482 tg->carryover_ios[rw] = 0;483 484 /*485 * Previous slice has expired. We must have trimmed it after last486 * bio dispatch. That means since start of last slice, we never used487 * that bandwidth. Do try to make use of that bandwidth while giving488 * credit.489 */490 if (time_after(start, tg->slice_start[rw]))491 tg->slice_start[rw] = start;492 493 tg->slice_end[rw] = jiffies + tg->td->throtl_slice;494 throtl_log(&tg->service_queue,495 "[%c] new slice with credit start=%lu end=%lu jiffies=%lu",496 rw == READ ? 'R' : 'W', tg->slice_start[rw],497 tg->slice_end[rw], jiffies);498}499 500static inline void throtl_start_new_slice(struct throtl_grp *tg, bool rw,501 bool clear_carryover)502{503 tg->bytes_disp[rw] = 0;504 tg->io_disp[rw] = 0;505 tg->slice_start[rw] = jiffies;506 tg->slice_end[rw] = jiffies + tg->td->throtl_slice;507 if (clear_carryover) {508 tg->carryover_bytes[rw] = 0;509 tg->carryover_ios[rw] = 0;510 }511 512 throtl_log(&tg->service_queue,513 "[%c] new slice start=%lu end=%lu jiffies=%lu",514 rw == READ ? 'R' : 'W', tg->slice_start[rw],515 tg->slice_end[rw], jiffies);516}517 518static inline void throtl_set_slice_end(struct throtl_grp *tg, bool rw,519 unsigned long jiffy_end)520{521 tg->slice_end[rw] = roundup(jiffy_end, tg->td->throtl_slice);522}523 524static inline void throtl_extend_slice(struct throtl_grp *tg, bool rw,525 unsigned long jiffy_end)526{527 throtl_set_slice_end(tg, rw, jiffy_end);528 throtl_log(&tg->service_queue,529 "[%c] extend slice start=%lu end=%lu jiffies=%lu",530 rw == READ ? 'R' : 'W', tg->slice_start[rw],531 tg->slice_end[rw], jiffies);532}533 534/* Determine if previously allocated or extended slice is complete or not */535static bool throtl_slice_used(struct throtl_grp *tg, bool rw)536{537 if (time_in_range(jiffies, tg->slice_start[rw], tg->slice_end[rw]))538 return false;539 540 return true;541}542 543static unsigned int calculate_io_allowed(u32 iops_limit,544 unsigned long jiffy_elapsed)545{546 unsigned int io_allowed;547 u64 tmp;548 549 /*550 * jiffy_elapsed should not be a big value as minimum iops can be551 * 1 then at max jiffy elapsed should be equivalent of 1 second as we552 * will allow dispatch after 1 second and after that slice should553 * have been trimmed.554 */555 556 tmp = (u64)iops_limit * jiffy_elapsed;557 do_div(tmp, HZ);558 559 if (tmp > UINT_MAX)560 io_allowed = UINT_MAX;561 else562 io_allowed = tmp;563 564 return io_allowed;565}566 567static u64 calculate_bytes_allowed(u64 bps_limit, unsigned long jiffy_elapsed)568{569 /*570 * Can result be wider than 64 bits?571 * We check against 62, not 64, due to ilog2 truncation.572 */573 if (ilog2(bps_limit) + ilog2(jiffy_elapsed) - ilog2(HZ) > 62)574 return U64_MAX;575 return mul_u64_u64_div_u64(bps_limit, (u64)jiffy_elapsed, (u64)HZ);576}577 578/* Trim the used slices and adjust slice start accordingly */579static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw)580{581 unsigned long time_elapsed;582 long long bytes_trim;583 int io_trim;584 585 BUG_ON(time_before(tg->slice_end[rw], tg->slice_start[rw]));586 587 /*588 * If bps are unlimited (-1), then time slice don't get589 * renewed. Don't try to trim the slice if slice is used. A new590 * slice will start when appropriate.591 */592 if (throtl_slice_used(tg, rw))593 return;594 595 /*596 * A bio has been dispatched. Also adjust slice_end. It might happen597 * that initially cgroup limit was very low resulting in high598 * slice_end, but later limit was bumped up and bio was dispatched599 * sooner, then we need to reduce slice_end. A high bogus slice_end600 * is bad because it does not allow new slice to start.601 */602 603 throtl_set_slice_end(tg, rw, jiffies + tg->td->throtl_slice);604 605 time_elapsed = rounddown(jiffies - tg->slice_start[rw],606 tg->td->throtl_slice);607 if (!time_elapsed)608 return;609 610 bytes_trim = calculate_bytes_allowed(tg_bps_limit(tg, rw),611 time_elapsed) +612 tg->carryover_bytes[rw];613 io_trim = calculate_io_allowed(tg_iops_limit(tg, rw), time_elapsed) +614 tg->carryover_ios[rw];615 if (bytes_trim <= 0 && io_trim <= 0)616 return;617 618 tg->carryover_bytes[rw] = 0;619 if ((long long)tg->bytes_disp[rw] >= bytes_trim)620 tg->bytes_disp[rw] -= bytes_trim;621 else622 tg->bytes_disp[rw] = 0;623 624 tg->carryover_ios[rw] = 0;625 if ((int)tg->io_disp[rw] >= io_trim)626 tg->io_disp[rw] -= io_trim;627 else628 tg->io_disp[rw] = 0;629 630 tg->slice_start[rw] += time_elapsed;631 632 throtl_log(&tg->service_queue,633 "[%c] trim slice nr=%lu bytes=%lld io=%d start=%lu end=%lu jiffies=%lu",634 rw == READ ? 'R' : 'W', time_elapsed / tg->td->throtl_slice,635 bytes_trim, io_trim, tg->slice_start[rw], tg->slice_end[rw],636 jiffies);637}638 639static void __tg_update_carryover(struct throtl_grp *tg, bool rw)640{641 unsigned long jiffy_elapsed = jiffies - tg->slice_start[rw];642 u64 bps_limit = tg_bps_limit(tg, rw);643 u32 iops_limit = tg_iops_limit(tg, rw);644 645 /*646 * If config is updated while bios are still throttled, calculate and647 * accumulate how many bytes/ios are waited across changes. And648 * carryover_bytes/ios will be used to calculate new wait time under new649 * configuration.650 */651 if (bps_limit != U64_MAX)652 tg->carryover_bytes[rw] +=653 calculate_bytes_allowed(bps_limit, jiffy_elapsed) -654 tg->bytes_disp[rw];655 if (iops_limit != UINT_MAX)656 tg->carryover_ios[rw] +=657 calculate_io_allowed(iops_limit, jiffy_elapsed) -658 tg->io_disp[rw];659}660 661static void tg_update_carryover(struct throtl_grp *tg)662{663 if (tg->service_queue.nr_queued[READ])664 __tg_update_carryover(tg, READ);665 if (tg->service_queue.nr_queued[WRITE])666 __tg_update_carryover(tg, WRITE);667 668 /* see comments in struct throtl_grp for meaning of these fields. */669 throtl_log(&tg->service_queue, "%s: %lld %lld %d %d\n", __func__,670 tg->carryover_bytes[READ], tg->carryover_bytes[WRITE],671 tg->carryover_ios[READ], tg->carryover_ios[WRITE]);672}673 674static unsigned long tg_within_iops_limit(struct throtl_grp *tg, struct bio *bio,675 u32 iops_limit)676{677 bool rw = bio_data_dir(bio);678 int io_allowed;679 unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;680 681 if (iops_limit == UINT_MAX) {682 return 0;683 }684 685 jiffy_elapsed = jiffies - tg->slice_start[rw];686 687 /* Round up to the next throttle slice, wait time must be nonzero */688 jiffy_elapsed_rnd = roundup(jiffy_elapsed + 1, tg->td->throtl_slice);689 io_allowed = calculate_io_allowed(iops_limit, jiffy_elapsed_rnd) +690 tg->carryover_ios[rw];691 if (io_allowed > 0 && tg->io_disp[rw] + 1 <= io_allowed)692 return 0;693 694 /* Calc approx time to dispatch */695 jiffy_wait = jiffy_elapsed_rnd - jiffy_elapsed;696 697 /* make sure at least one io can be dispatched after waiting */698 jiffy_wait = max(jiffy_wait, HZ / iops_limit + 1);699 return jiffy_wait;700}701 702static unsigned long tg_within_bps_limit(struct throtl_grp *tg, struct bio *bio,703 u64 bps_limit)704{705 bool rw = bio_data_dir(bio);706 long long bytes_allowed;707 u64 extra_bytes;708 unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;709 unsigned int bio_size = throtl_bio_data_size(bio);710 711 /* no need to throttle if this bio's bytes have been accounted */712 if (bps_limit == U64_MAX || bio_flagged(bio, BIO_BPS_THROTTLED)) {713 return 0;714 }715 716 jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw];717 718 /* Slice has just started. Consider one slice interval */719 if (!jiffy_elapsed)720 jiffy_elapsed_rnd = tg->td->throtl_slice;721 722 jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, tg->td->throtl_slice);723 bytes_allowed = calculate_bytes_allowed(bps_limit, jiffy_elapsed_rnd) +724 tg->carryover_bytes[rw];725 if (bytes_allowed > 0 && tg->bytes_disp[rw] + bio_size <= bytes_allowed)726 return 0;727 728 /* Calc approx time to dispatch */729 extra_bytes = tg->bytes_disp[rw] + bio_size - bytes_allowed;730 jiffy_wait = div64_u64(extra_bytes * HZ, bps_limit);731 732 if (!jiffy_wait)733 jiffy_wait = 1;734 735 /*736 * This wait time is without taking into consideration the rounding737 * up we did. Add that time also.738 */739 jiffy_wait = jiffy_wait + (jiffy_elapsed_rnd - jiffy_elapsed);740 return jiffy_wait;741}742 743/*744 * Returns whether one can dispatch a bio or not. Also returns approx number745 * of jiffies to wait before this bio is with-in IO rate and can be dispatched746 */747static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio,748 unsigned long *wait)749{750 bool rw = bio_data_dir(bio);751 unsigned long bps_wait = 0, iops_wait = 0, max_wait = 0;752 u64 bps_limit = tg_bps_limit(tg, rw);753 u32 iops_limit = tg_iops_limit(tg, rw);754 755 /*756 * Currently whole state machine of group depends on first bio757 * queued in the group bio list. So one should not be calling758 * this function with a different bio if there are other bios759 * queued.760 */761 BUG_ON(tg->service_queue.nr_queued[rw] &&762 bio != throtl_peek_queued(&tg->service_queue.queued[rw]));763 764 /* If tg->bps = -1, then BW is unlimited */765 if ((bps_limit == U64_MAX && iops_limit == UINT_MAX) ||766 tg->flags & THROTL_TG_CANCELING) {767 if (wait)768 *wait = 0;769 return true;770 }771 772 /*773 * If previous slice expired, start a new one otherwise renew/extend774 * existing slice to make sure it is at least throtl_slice interval775 * long since now. New slice is started only for empty throttle group.776 * If there is queued bio, that means there should be an active777 * slice and it should be extended instead.778 */779 if (throtl_slice_used(tg, rw) && !(tg->service_queue.nr_queued[rw]))780 throtl_start_new_slice(tg, rw, true);781 else {782 if (time_before(tg->slice_end[rw],783 jiffies + tg->td->throtl_slice))784 throtl_extend_slice(tg, rw,785 jiffies + tg->td->throtl_slice);786 }787 788 bps_wait = tg_within_bps_limit(tg, bio, bps_limit);789 iops_wait = tg_within_iops_limit(tg, bio, iops_limit);790 if (bps_wait + iops_wait == 0) {791 if (wait)792 *wait = 0;793 return true;794 }795 796 max_wait = max(bps_wait, iops_wait);797 798 if (wait)799 *wait = max_wait;800 801 if (time_before(tg->slice_end[rw], jiffies + max_wait))802 throtl_extend_slice(tg, rw, jiffies + max_wait);803 804 return false;805}806 807static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio)808{809 bool rw = bio_data_dir(bio);810 unsigned int bio_size = throtl_bio_data_size(bio);811 812 /* Charge the bio to the group */813 if (!bio_flagged(bio, BIO_BPS_THROTTLED)) {814 tg->bytes_disp[rw] += bio_size;815 tg->last_bytes_disp[rw] += bio_size;816 }817 818 tg->io_disp[rw]++;819 tg->last_io_disp[rw]++;820}821 822/**823 * throtl_add_bio_tg - add a bio to the specified throtl_grp824 * @bio: bio to add825 * @qn: qnode to use826 * @tg: the target throtl_grp827 *828 * Add @bio to @tg's service_queue using @qn. If @qn is not specified,829 * tg->qnode_on_self[] is used.830 */831static void throtl_add_bio_tg(struct bio *bio, struct throtl_qnode *qn,832 struct throtl_grp *tg)833{834 struct throtl_service_queue *sq = &tg->service_queue;835 bool rw = bio_data_dir(bio);836 837 if (!qn)838 qn = &tg->qnode_on_self[rw];839 840 /*841 * If @tg doesn't currently have any bios queued in the same842 * direction, queueing @bio can change when @tg should be843 * dispatched. Mark that @tg was empty. This is automatically844 * cleared on the next tg_update_disptime().845 */846 if (!sq->nr_queued[rw])847 tg->flags |= THROTL_TG_WAS_EMPTY;848 849 throtl_qnode_add_bio(bio, qn, &sq->queued[rw]);850 851 sq->nr_queued[rw]++;852 throtl_enqueue_tg(tg);853}854 855static void tg_update_disptime(struct throtl_grp *tg)856{857 struct throtl_service_queue *sq = &tg->service_queue;858 unsigned long read_wait = -1, write_wait = -1, min_wait = -1, disptime;859 struct bio *bio;860 861 bio = throtl_peek_queued(&sq->queued[READ]);862 if (bio)863 tg_may_dispatch(tg, bio, &read_wait);864 865 bio = throtl_peek_queued(&sq->queued[WRITE]);866 if (bio)867 tg_may_dispatch(tg, bio, &write_wait);868 869 min_wait = min(read_wait, write_wait);870 disptime = jiffies + min_wait;871 872 /* Update dispatch time */873 throtl_rb_erase(&tg->rb_node, tg->service_queue.parent_sq);874 tg->disptime = disptime;875 tg_service_queue_add(tg);876 877 /* see throtl_add_bio_tg() */878 tg->flags &= ~THROTL_TG_WAS_EMPTY;879}880 881static void start_parent_slice_with_credit(struct throtl_grp *child_tg,882 struct throtl_grp *parent_tg, bool rw)883{884 if (throtl_slice_used(parent_tg, rw)) {885 throtl_start_new_slice_with_credit(parent_tg, rw,886 child_tg->slice_start[rw]);887 }888 889}890 891static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw)892{893 struct throtl_service_queue *sq = &tg->service_queue;894 struct throtl_service_queue *parent_sq = sq->parent_sq;895 struct throtl_grp *parent_tg = sq_to_tg(parent_sq);896 struct throtl_grp *tg_to_put = NULL;897 struct bio *bio;898 899 /*900 * @bio is being transferred from @tg to @parent_sq. Popping a bio901 * from @tg may put its reference and @parent_sq might end up902 * getting released prematurely. Remember the tg to put and put it903 * after @bio is transferred to @parent_sq.904 */905 bio = throtl_pop_queued(&sq->queued[rw], &tg_to_put);906 sq->nr_queued[rw]--;907 908 throtl_charge_bio(tg, bio);909 910 /*911 * If our parent is another tg, we just need to transfer @bio to912 * the parent using throtl_add_bio_tg(). If our parent is913 * @td->service_queue, @bio is ready to be issued. Put it on its914 * bio_lists[] and decrease total number queued. The caller is915 * responsible for issuing these bios.916 */917 if (parent_tg) {918 throtl_add_bio_tg(bio, &tg->qnode_on_parent[rw], parent_tg);919 start_parent_slice_with_credit(tg, parent_tg, rw);920 } else {921 bio_set_flag(bio, BIO_BPS_THROTTLED);922 throtl_qnode_add_bio(bio, &tg->qnode_on_parent[rw],923 &parent_sq->queued[rw]);924 BUG_ON(tg->td->nr_queued[rw] <= 0);925 tg->td->nr_queued[rw]--;926 }927 928 throtl_trim_slice(tg, rw);929 930 if (tg_to_put)931 blkg_put(tg_to_blkg(tg_to_put));932}933 934static int throtl_dispatch_tg(struct throtl_grp *tg)935{936 struct throtl_service_queue *sq = &tg->service_queue;937 unsigned int nr_reads = 0, nr_writes = 0;938 unsigned int max_nr_reads = THROTL_GRP_QUANTUM * 3 / 4;939 unsigned int max_nr_writes = THROTL_GRP_QUANTUM - max_nr_reads;940 struct bio *bio;941 942 /* Try to dispatch 75% READS and 25% WRITES */943 944 while ((bio = throtl_peek_queued(&sq->queued[READ])) &&945 tg_may_dispatch(tg, bio, NULL)) {946 947 tg_dispatch_one_bio(tg, READ);948 nr_reads++;949 950 if (nr_reads >= max_nr_reads)951 break;952 }953 954 while ((bio = throtl_peek_queued(&sq->queued[WRITE])) &&955 tg_may_dispatch(tg, bio, NULL)) {956 957 tg_dispatch_one_bio(tg, WRITE);958 nr_writes++;959 960 if (nr_writes >= max_nr_writes)961 break;962 }963 964 return nr_reads + nr_writes;965}966 967static int throtl_select_dispatch(struct throtl_service_queue *parent_sq)968{969 unsigned int nr_disp = 0;970 971 while (1) {972 struct throtl_grp *tg;973 struct throtl_service_queue *sq;974 975 if (!parent_sq->nr_pending)976 break;977 978 tg = throtl_rb_first(parent_sq);979 if (!tg)980 break;981 982 if (time_before(jiffies, tg->disptime))983 break;984 985 nr_disp += throtl_dispatch_tg(tg);986 987 sq = &tg->service_queue;988 if (sq->nr_queued[READ] || sq->nr_queued[WRITE])989 tg_update_disptime(tg);990 else991 throtl_dequeue_tg(tg);992 993 if (nr_disp >= THROTL_QUANTUM)994 break;995 }996 997 return nr_disp;998}999 1000/**1001 * throtl_pending_timer_fn - timer function for service_queue->pending_timer1002 * @t: the pending_timer member of the throtl_service_queue being serviced1003 *1004 * This timer is armed when a child throtl_grp with active bio's become1005 * pending and queued on the service_queue's pending_tree and expires when1006 * the first child throtl_grp should be dispatched. This function1007 * dispatches bio's from the children throtl_grps to the parent1008 * service_queue.1009 *1010 * If the parent's parent is another throtl_grp, dispatching is propagated1011 * by either arming its pending_timer or repeating dispatch directly. If1012 * the top-level service_tree is reached, throtl_data->dispatch_work is1013 * kicked so that the ready bio's are issued.1014 */1015static void throtl_pending_timer_fn(struct timer_list *t)1016{1017 struct throtl_service_queue *sq = from_timer(sq, t, pending_timer);1018 struct throtl_grp *tg = sq_to_tg(sq);1019 struct throtl_data *td = sq_to_td(sq);1020 struct throtl_service_queue *parent_sq;1021 struct request_queue *q;1022 bool dispatched;1023 int ret;1024 1025 /* throtl_data may be gone, so figure out request queue by blkg */1026 if (tg)1027 q = tg->pd.blkg->q;1028 else1029 q = td->queue;1030 1031 spin_lock_irq(&q->queue_lock);1032 1033 if (!q->root_blkg)1034 goto out_unlock;1035 1036again:1037 parent_sq = sq->parent_sq;1038 dispatched = false;1039 1040 while (true) {1041 throtl_log(sq, "dispatch nr_queued=%u read=%u write=%u",1042 sq->nr_queued[READ] + sq->nr_queued[WRITE],1043 sq->nr_queued[READ], sq->nr_queued[WRITE]);1044 1045 ret = throtl_select_dispatch(sq);1046 if (ret) {1047 throtl_log(sq, "bios disp=%u", ret);1048 dispatched = true;1049 }1050 1051 if (throtl_schedule_next_dispatch(sq, false))1052 break;1053 1054 /* this dispatch windows is still open, relax and repeat */1055 spin_unlock_irq(&q->queue_lock);1056 cpu_relax();1057 spin_lock_irq(&q->queue_lock);1058 }1059 1060 if (!dispatched)1061 goto out_unlock;1062 1063 if (parent_sq) {1064 /* @parent_sq is another throl_grp, propagate dispatch */1065 if (tg->flags & THROTL_TG_WAS_EMPTY) {1066 tg_update_disptime(tg);1067 if (!throtl_schedule_next_dispatch(parent_sq, false)) {1068 /* window is already open, repeat dispatching */1069 sq = parent_sq;1070 tg = sq_to_tg(sq);1071 goto again;1072 }1073 }1074 } else {1075 /* reached the top-level, queue issuing */1076 queue_work(kthrotld_workqueue, &td->dispatch_work);1077 }1078out_unlock:1079 spin_unlock_irq(&q->queue_lock);1080}1081 1082/**1083 * blk_throtl_dispatch_work_fn - work function for throtl_data->dispatch_work1084 * @work: work item being executed1085 *1086 * This function is queued for execution when bios reach the bio_lists[]1087 * of throtl_data->service_queue. Those bios are ready and issued by this1088 * function.1089 */1090static void blk_throtl_dispatch_work_fn(struct work_struct *work)1091{1092 struct throtl_data *td = container_of(work, struct throtl_data,1093 dispatch_work);1094 struct throtl_service_queue *td_sq = &td->service_queue;1095 struct request_queue *q = td->queue;1096 struct bio_list bio_list_on_stack;1097 struct bio *bio;1098 struct blk_plug plug;1099 int rw;1100 1101 bio_list_init(&bio_list_on_stack);1102 1103 spin_lock_irq(&q->queue_lock);1104 for (rw = READ; rw <= WRITE; rw++)1105 while ((bio = throtl_pop_queued(&td_sq->queued[rw], NULL)))1106 bio_list_add(&bio_list_on_stack, bio);1107 spin_unlock_irq(&q->queue_lock);1108 1109 if (!bio_list_empty(&bio_list_on_stack)) {1110 blk_start_plug(&plug);1111 while ((bio = bio_list_pop(&bio_list_on_stack)))1112 submit_bio_noacct_nocheck(bio);1113 blk_finish_plug(&plug);1114 }1115}1116 1117static u64 tg_prfill_conf_u64(struct seq_file *sf, struct blkg_policy_data *pd,1118 int off)1119{1120 struct throtl_grp *tg = pd_to_tg(pd);1121 u64 v = *(u64 *)((void *)tg + off);1122 1123 if (v == U64_MAX)1124 return 0;1125 return __blkg_prfill_u64(sf, pd, v);1126}1127 1128static u64 tg_prfill_conf_uint(struct seq_file *sf, struct blkg_policy_data *pd,1129 int off)1130{1131 struct throtl_grp *tg = pd_to_tg(pd);1132 unsigned int v = *(unsigned int *)((void *)tg + off);1133 1134 if (v == UINT_MAX)1135 return 0;1136 return __blkg_prfill_u64(sf, pd, v);1137}1138 1139static int tg_print_conf_u64(struct seq_file *sf, void *v)1140{1141 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_conf_u64,1142 &blkcg_policy_throtl, seq_cft(sf)->private, false);1143 return 0;1144}1145 1146static int tg_print_conf_uint(struct seq_file *sf, void *v)1147{1148 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_conf_uint,1149 &blkcg_policy_throtl, seq_cft(sf)->private, false);1150 return 0;1151}1152 1153static void tg_conf_updated(struct throtl_grp *tg, bool global)1154{1155 struct throtl_service_queue *sq = &tg->service_queue;1156 struct cgroup_subsys_state *pos_css;1157 struct blkcg_gq *blkg;1158 1159 throtl_log(&tg->service_queue,1160 "limit change rbps=%llu wbps=%llu riops=%u wiops=%u",1161 tg_bps_limit(tg, READ), tg_bps_limit(tg, WRITE),1162 tg_iops_limit(tg, READ), tg_iops_limit(tg, WRITE));1163 1164 rcu_read_lock();1165 /*1166 * Update has_rules[] flags for the updated tg's subtree. A tg is1167 * considered to have rules if either the tg itself or any of its1168 * ancestors has rules. This identifies groups without any1169 * restrictions in the whole hierarchy and allows them to bypass1170 * blk-throttle.1171 */1172 blkg_for_each_descendant_pre(blkg, pos_css,1173 global ? tg->td->queue->root_blkg : tg_to_blkg(tg)) {1174 struct throtl_grp *this_tg = blkg_to_tg(blkg);1175 1176 tg_update_has_rules(this_tg);1177 /* ignore root/second level */1178 if (!cgroup_subsys_on_dfl(io_cgrp_subsys) || !blkg->parent ||1179 !blkg->parent->parent)1180 continue;1181 }1182 rcu_read_unlock();1183 1184 /*1185 * We're already holding queue_lock and know @tg is valid. Let's1186 * apply the new config directly.1187 *1188 * Restart the slices for both READ and WRITES. It might happen1189 * that a group's limit are dropped suddenly and we don't want to1190 * account recently dispatched IO with new low rate.1191 */1192 throtl_start_new_slice(tg, READ, false);1193 throtl_start_new_slice(tg, WRITE, false);1194 1195 if (tg->flags & THROTL_TG_PENDING) {1196 tg_update_disptime(tg);1197 throtl_schedule_next_dispatch(sq->parent_sq, true);1198 }1199}1200 1201static int blk_throtl_init(struct gendisk *disk)1202{1203 struct request_queue *q = disk->queue;1204 struct throtl_data *td;1205 int ret;1206 1207 td = kzalloc_node(sizeof(*td), GFP_KERNEL, q->node);1208 if (!td)1209 return -ENOMEM;1210 1211 INIT_WORK(&td->dispatch_work, blk_throtl_dispatch_work_fn);1212 throtl_service_queue_init(&td->service_queue);1213 1214 /*1215 * Freeze queue before activating policy, to synchronize with IO path,1216 * which is protected by 'q_usage_counter'.1217 */1218 blk_mq_freeze_queue(disk->queue);1219 blk_mq_quiesce_queue(disk->queue);1220 1221 q->td = td;1222 td->queue = q;1223 1224 /* activate policy */1225 ret = blkcg_activate_policy(disk, &blkcg_policy_throtl);1226 if (ret) {1227 q->td = NULL;1228 kfree(td);1229 goto out;1230 }1231 1232 if (blk_queue_nonrot(q))1233 td->throtl_slice = DFL_THROTL_SLICE_SSD;1234 else1235 td->throtl_slice = DFL_THROTL_SLICE_HD;1236 td->track_bio_latency = !queue_is_mq(q);1237 if (!td->track_bio_latency)1238 blk_stat_enable_accounting(q);1239 1240out:1241 blk_mq_unquiesce_queue(disk->queue);1242 blk_mq_unfreeze_queue(disk->queue);1243 1244 return ret;1245}1246 1247 1248static ssize_t tg_set_conf(struct kernfs_open_file *of,1249 char *buf, size_t nbytes, loff_t off, bool is_u64)1250{1251 struct blkcg *blkcg = css_to_blkcg(of_css(of));1252 struct blkg_conf_ctx ctx;1253 struct throtl_grp *tg;1254 int ret;1255 u64 v;1256 1257 blkg_conf_init(&ctx, buf);1258 1259 ret = blkg_conf_open_bdev(&ctx);1260 if (ret)1261 goto out_finish;1262 1263 if (!blk_throtl_activated(ctx.bdev->bd_queue)) {1264 ret = blk_throtl_init(ctx.bdev->bd_disk);1265 if (ret)1266 goto out_finish;1267 }1268 1269 ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, &ctx);1270 if (ret)1271 goto out_finish;1272 1273 ret = -EINVAL;1274 if (sscanf(ctx.body, "%llu", &v) != 1)1275 goto out_finish;1276 if (!v)1277 v = U64_MAX;1278 1279 tg = blkg_to_tg(ctx.blkg);1280 tg_update_carryover(tg);1281 1282 if (is_u64)1283 *(u64 *)((void *)tg + of_cft(of)->private) = v;1284 else1285 *(unsigned int *)((void *)tg + of_cft(of)->private) = v;1286 1287 tg_conf_updated(tg, false);1288 ret = 0;1289out_finish:1290 blkg_conf_exit(&ctx);1291 return ret ?: nbytes;1292}1293 1294static ssize_t tg_set_conf_u64(struct kernfs_open_file *of,1295 char *buf, size_t nbytes, loff_t off)1296{1297 return tg_set_conf(of, buf, nbytes, off, true);1298}1299 1300static ssize_t tg_set_conf_uint(struct kernfs_open_file *of,1301 char *buf, size_t nbytes, loff_t off)1302{1303 return tg_set_conf(of, buf, nbytes, off, false);1304}1305 1306static int tg_print_rwstat(struct seq_file *sf, void *v)1307{1308 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),1309 blkg_prfill_rwstat, &blkcg_policy_throtl,1310 seq_cft(sf)->private, true);1311 return 0;1312}1313 1314static u64 tg_prfill_rwstat_recursive(struct seq_file *sf,1315 struct blkg_policy_data *pd, int off)1316{1317 struct blkg_rwstat_sample sum;1318 1319 blkg_rwstat_recursive_sum(pd_to_blkg(pd), &blkcg_policy_throtl, off,1320 &sum);1321 return __blkg_prfill_rwstat(sf, pd, &sum);1322}1323 1324static int tg_print_rwstat_recursive(struct seq_file *sf, void *v)1325{1326 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),1327 tg_prfill_rwstat_recursive, &blkcg_policy_throtl,1328 seq_cft(sf)->private, true);1329 return 0;1330}1331 1332static struct cftype throtl_legacy_files[] = {1333 {1334 .name = "throttle.read_bps_device",1335 .private = offsetof(struct throtl_grp, bps[READ]),1336 .seq_show = tg_print_conf_u64,1337 .write = tg_set_conf_u64,1338 },1339 {1340 .name = "throttle.write_bps_device",1341 .private = offsetof(struct throtl_grp, bps[WRITE]),1342 .seq_show = tg_print_conf_u64,1343 .write = tg_set_conf_u64,1344 },1345 {1346 .name = "throttle.read_iops_device",1347 .private = offsetof(struct throtl_grp, iops[READ]),1348 .seq_show = tg_print_conf_uint,1349 .write = tg_set_conf_uint,1350 },1351 {1352 .name = "throttle.write_iops_device",1353 .private = offsetof(struct throtl_grp, iops[WRITE]),1354 .seq_show = tg_print_conf_uint,1355 .write = tg_set_conf_uint,1356 },1357 {1358 .name = "throttle.io_service_bytes",1359 .private = offsetof(struct throtl_grp, stat_bytes),1360 .seq_show = tg_print_rwstat,1361 },1362 {1363 .name = "throttle.io_service_bytes_recursive",1364 .private = offsetof(struct throtl_grp, stat_bytes),1365 .seq_show = tg_print_rwstat_recursive,1366 },1367 {1368 .name = "throttle.io_serviced",1369 .private = offsetof(struct throtl_grp, stat_ios),1370 .seq_show = tg_print_rwstat,1371 },1372 {1373 .name = "throttle.io_serviced_recursive",1374 .private = offsetof(struct throtl_grp, stat_ios),1375 .seq_show = tg_print_rwstat_recursive,1376 },1377 { } /* terminate */1378};1379 1380static u64 tg_prfill_limit(struct seq_file *sf, struct blkg_policy_data *pd,1381 int off)1382{1383 struct throtl_grp *tg = pd_to_tg(pd);1384 const char *dname = blkg_dev_name(pd->blkg);1385 u64 bps_dft;1386 unsigned int iops_dft;1387 1388 if (!dname)1389 return 0;1390 1391 bps_dft = U64_MAX;1392 iops_dft = UINT_MAX;1393 1394 if (tg->bps[READ] == bps_dft &&1395 tg->bps[WRITE] == bps_dft &&1396 tg->iops[READ] == iops_dft &&1397 tg->iops[WRITE] == iops_dft)1398 return 0;1399 1400 seq_printf(sf, "%s", dname);1401 if (tg->bps[READ] == U64_MAX)1402 seq_printf(sf, " rbps=max");1403 else1404 seq_printf(sf, " rbps=%llu", tg->bps[READ]);1405 1406 if (tg->bps[WRITE] == U64_MAX)1407 seq_printf(sf, " wbps=max");1408 else1409 seq_printf(sf, " wbps=%llu", tg->bps[WRITE]);1410 1411 if (tg->iops[READ] == UINT_MAX)1412 seq_printf(sf, " riops=max");1413 else1414 seq_printf(sf, " riops=%u", tg->iops[READ]);1415 1416 if (tg->iops[WRITE] == UINT_MAX)1417 seq_printf(sf, " wiops=max");1418 else1419 seq_printf(sf, " wiops=%u", tg->iops[WRITE]);1420 1421 seq_printf(sf, "\n");1422 return 0;1423}1424 1425static int tg_print_limit(struct seq_file *sf, void *v)1426{1427 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_limit,1428 &blkcg_policy_throtl, seq_cft(sf)->private, false);1429 return 0;1430}1431 1432static ssize_t tg_set_limit(struct kernfs_open_file *of,1433 char *buf, size_t nbytes, loff_t off)1434{1435 struct blkcg *blkcg = css_to_blkcg(of_css(of));1436 struct blkg_conf_ctx ctx;1437 struct throtl_grp *tg;1438 u64 v[4];1439 int ret;1440 1441 blkg_conf_init(&ctx, buf);1442 1443 ret = blkg_conf_open_bdev(&ctx);1444 if (ret)1445 goto out_finish;1446 1447 if (!blk_throtl_activated(ctx.bdev->bd_queue)) {1448 ret = blk_throtl_init(ctx.bdev->bd_disk);1449 if (ret)1450 goto out_finish;1451 }1452 1453 ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, &ctx);1454 if (ret)1455 goto out_finish;1456 1457 tg = blkg_to_tg(ctx.blkg);1458 tg_update_carryover(tg);1459 1460 v[0] = tg->bps[READ];1461 v[1] = tg->bps[WRITE];1462 v[2] = tg->iops[READ];1463 v[3] = tg->iops[WRITE];1464 1465 while (true) {1466 char tok[27]; /* wiops=18446744073709551616 */1467 char *p;1468 u64 val = U64_MAX;1469 int len;1470 1471 if (sscanf(ctx.body, "%26s%n", tok, &len) != 1)1472 break;1473 if (tok[0] == '\0')1474 break;1475 ctx.body += len;1476 1477 ret = -EINVAL;1478 p = tok;1479 strsep(&p, "=");1480 if (!p || (sscanf(p, "%llu", &val) != 1 && strcmp(p, "max")))1481 goto out_finish;1482 1483 ret = -ERANGE;1484 if (!val)1485 goto out_finish;1486 1487 ret = -EINVAL;1488 if (!strcmp(tok, "rbps") && val > 1)1489 v[0] = val;1490 else if (!strcmp(tok, "wbps") && val > 1)1491 v[1] = val;1492 else if (!strcmp(tok, "riops") && val > 1)1493 v[2] = min_t(u64, val, UINT_MAX);1494 else if (!strcmp(tok, "wiops") && val > 1)1495 v[3] = min_t(u64, val, UINT_MAX);1496 else1497 goto out_finish;1498 }1499 1500 tg->bps[READ] = v[0];1501 tg->bps[WRITE] = v[1];1502 tg->iops[READ] = v[2];1503 tg->iops[WRITE] = v[3];1504 1505 tg_conf_updated(tg, false);1506 ret = 0;1507out_finish:1508 blkg_conf_exit(&ctx);1509 return ret ?: nbytes;1510}1511 1512static struct cftype throtl_files[] = {1513 {1514 .name = "max",1515 .flags = CFTYPE_NOT_ON_ROOT,1516 .seq_show = tg_print_limit,1517 .write = tg_set_limit,1518 },1519 { } /* terminate */1520};1521 1522static void throtl_shutdown_wq(struct request_queue *q)1523{1524 struct throtl_data *td = q->td;1525 1526 cancel_work_sync(&td->dispatch_work);1527}1528 1529struct blkcg_policy blkcg_policy_throtl = {1530 .dfl_cftypes = throtl_files,1531 .legacy_cftypes = throtl_legacy_files,1532 1533 .pd_alloc_fn = throtl_pd_alloc,1534 .pd_init_fn = throtl_pd_init,1535 .pd_online_fn = throtl_pd_online,1536 .pd_free_fn = throtl_pd_free,1537};1538 1539void blk_throtl_cancel_bios(struct gendisk *disk)1540{1541 struct request_queue *q = disk->queue;1542 struct cgroup_subsys_state *pos_css;1543 struct blkcg_gq *blkg;1544 1545 if (!blk_throtl_activated(q))1546 return;1547 1548 spin_lock_irq(&q->queue_lock);1549 /*1550 * queue_lock is held, rcu lock is not needed here technically.1551 * However, rcu lock is still held to emphasize that following1552 * path need RCU protection and to prevent warning from lockdep.1553 */1554 rcu_read_lock();1555 blkg_for_each_descendant_post(blkg, pos_css, q->root_blkg) {1556 struct throtl_grp *tg = blkg_to_tg(blkg);1557 struct throtl_service_queue *sq = &tg->service_queue;1558 1559 /*1560 * Set the flag to make sure throtl_pending_timer_fn() won't1561 * stop until all throttled bios are dispatched.1562 */1563 tg->flags |= THROTL_TG_CANCELING;1564 1565 /*1566 * Do not dispatch cgroup without THROTL_TG_PENDING or cgroup1567 * will be inserted to service queue without THROTL_TG_PENDING1568 * set in tg_update_disptime below. Then IO dispatched from1569 * child in tg_dispatch_one_bio will trigger double insertion1570 * and corrupt the tree.1571 */1572 if (!(tg->flags & THROTL_TG_PENDING))1573 continue;1574 1575 /*1576 * Update disptime after setting the above flag to make sure1577 * throtl_select_dispatch() won't exit without dispatching.1578 */1579 tg_update_disptime(tg);1580 1581 throtl_schedule_pending_timer(sq, jiffies + 1);1582 }1583 rcu_read_unlock();1584 spin_unlock_irq(&q->queue_lock);1585}1586 1587static bool tg_within_limit(struct throtl_grp *tg, struct bio *bio, bool rw)1588{1589 /* throtl is FIFO - if bios are already queued, should queue */1590 if (tg->service_queue.nr_queued[rw])1591 return false;1592 1593 return tg_may_dispatch(tg, bio, NULL);1594}1595 1596static void tg_dispatch_in_debt(struct throtl_grp *tg, struct bio *bio, bool rw)1597{1598 if (!bio_flagged(bio, BIO_BPS_THROTTLED))1599 tg->carryover_bytes[rw] -= throtl_bio_data_size(bio);1600 tg->carryover_ios[rw]--;1601}1602 1603bool __blk_throtl_bio(struct bio *bio)1604{1605 struct request_queue *q = bdev_get_queue(bio->bi_bdev);1606 struct blkcg_gq *blkg = bio->bi_blkg;1607 struct throtl_qnode *qn = NULL;1608 struct throtl_grp *tg = blkg_to_tg(blkg);1609 struct throtl_service_queue *sq;1610 bool rw = bio_data_dir(bio);1611 bool throttled = false;1612 struct throtl_data *td = tg->td;1613 1614 rcu_read_lock();1615 spin_lock_irq(&q->queue_lock);1616 sq = &tg->service_queue;1617 1618 while (true) {1619 if (tg_within_limit(tg, bio, rw)) {1620 /* within limits, let's charge and dispatch directly */1621 throtl_charge_bio(tg, bio);1622 1623 /*1624 * We need to trim slice even when bios are not being1625 * queued otherwise it might happen that a bio is not1626 * queued for a long time and slice keeps on extending1627 * and trim is not called for a long time. Now if limits1628 * are reduced suddenly we take into account all the IO1629 * dispatched so far at new low rate and * newly queued1630 * IO gets a really long dispatch time.1631 *1632 * So keep on trimming slice even if bio is not queued.1633 */1634 throtl_trim_slice(tg, rw);1635 } else if (bio_issue_as_root_blkg(bio)) {1636 /*1637 * IOs which may cause priority inversions are1638 * dispatched directly, even if they're over limit.1639 * Debts are handled by carryover_bytes/ios while1640 * calculating wait time.1641 */1642 tg_dispatch_in_debt(tg, bio, rw);1643 } else {1644 /* if above limits, break to queue */1645 break;1646 }1647 1648 /*1649 * @bio passed through this layer without being throttled.1650 * Climb up the ladder. If we're already at the top, it1651 * can be executed directly.1652 */1653 qn = &tg->qnode_on_parent[rw];1654 sq = sq->parent_sq;1655 tg = sq_to_tg(sq);1656 if (!tg) {1657 bio_set_flag(bio, BIO_BPS_THROTTLED);1658 goto out_unlock;1659 }1660 }1661 1662 /* out-of-limit, queue to @tg */1663 throtl_log(sq, "[%c] bio. bdisp=%llu sz=%u bps=%llu iodisp=%u iops=%u queued=%d/%d",1664 rw == READ ? 'R' : 'W',1665 tg->bytes_disp[rw], bio->bi_iter.bi_size,1666 tg_bps_limit(tg, rw),1667 tg->io_disp[rw], tg_iops_limit(tg, rw),1668 sq->nr_queued[READ], sq->nr_queued[WRITE]);1669 1670 td->nr_queued[rw]++;1671 throtl_add_bio_tg(bio, qn, tg);1672 throttled = true;1673 1674 /*1675 * Update @tg's dispatch time and force schedule dispatch if @tg1676 * was empty before @bio. The forced scheduling isn't likely to1677 * cause undue delay as @bio is likely to be dispatched directly if1678 * its @tg's disptime is not in the future.1679 */1680 if (tg->flags & THROTL_TG_WAS_EMPTY) {1681 tg_update_disptime(tg);1682 throtl_schedule_next_dispatch(tg->service_queue.parent_sq, true);1683 }1684 1685out_unlock:1686 spin_unlock_irq(&q->queue_lock);1687 1688 rcu_read_unlock();1689 return throttled;1690}1691 1692void blk_throtl_exit(struct gendisk *disk)1693{1694 struct request_queue *q = disk->queue;1695 1696 if (!blk_throtl_activated(q))1697 return;1698 1699 del_timer_sync(&q->td->service_queue.pending_timer);1700 throtl_shutdown_wq(q);1701 blkcg_deactivate_policy(disk, &blkcg_policy_throtl);1702 kfree(q->td);1703}1704 1705static int __init throtl_init(void)1706{1707 kthrotld_workqueue = alloc_workqueue("kthrotld", WQ_MEM_RECLAIM, 0);1708 if (!kthrotld_workqueue)1709 panic("Failed to create kthrotld\n");1710 1711 return blkcg_policy_register(&blkcg_policy_throtl);1712}1713 1714module_init(throtl_init);1715