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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Copyright (C) 2002 Sistina Software (UK) Limited.4 * Copyright (C) 2006 Red Hat GmbH5 *6 * This file is released under the GPL.7 *8 * Kcopyd provides a simple interface for copying an area of one9 * block-device to one or more other block-devices, with an asynchronous10 * completion notification.11 */12 13#include <linux/types.h>14#include <linux/atomic.h>15#include <linux/blkdev.h>16#include <linux/fs.h>17#include <linux/init.h>18#include <linux/list.h>19#include <linux/mempool.h>20#include <linux/module.h>21#include <linux/pagemap.h>22#include <linux/slab.h>23#include <linux/vmalloc.h>24#include <linux/workqueue.h>25#include <linux/mutex.h>26#include <linux/delay.h>27#include <linux/device-mapper.h>28#include <linux/dm-kcopyd.h>29 30#include "dm-core.h"31 32#define SPLIT_COUNT 833#define MIN_JOBS 834 35#define DEFAULT_SUB_JOB_SIZE_KB 51236#define MAX_SUB_JOB_SIZE_KB 102437 38static unsigned int kcopyd_subjob_size_kb = DEFAULT_SUB_JOB_SIZE_KB;39 40module_param(kcopyd_subjob_size_kb, uint, 0644);41MODULE_PARM_DESC(kcopyd_subjob_size_kb, "Sub-job size for dm-kcopyd clients");42 43static unsigned int dm_get_kcopyd_subjob_size(void)44{45 unsigned int sub_job_size_kb;46 47 sub_job_size_kb = __dm_get_module_param(&kcopyd_subjob_size_kb,48 DEFAULT_SUB_JOB_SIZE_KB,49 MAX_SUB_JOB_SIZE_KB);50 51 return sub_job_size_kb << 1;52}53 54/*55 *----------------------------------------------------------------56 * Each kcopyd client has its own little pool of preallocated57 * pages for kcopyd io.58 *---------------------------------------------------------------59 */60struct dm_kcopyd_client {61 struct page_list *pages;62 unsigned int nr_reserved_pages;63 unsigned int nr_free_pages;64 unsigned int sub_job_size;65 66 struct dm_io_client *io_client;67 68 wait_queue_head_t destroyq;69 70 mempool_t job_pool;71 72 struct workqueue_struct *kcopyd_wq;73 struct work_struct kcopyd_work;74 75 struct dm_kcopyd_throttle *throttle;76 77 atomic_t nr_jobs;78 79/*80 * We maintain four lists of jobs:81 *82 * i) jobs waiting for pages83 * ii) jobs that have pages, and are waiting for the io to be issued.84 * iii) jobs that don't need to do any IO and just run a callback85 * iv) jobs that have completed.86 *87 * All four of these are protected by job_lock.88 */89 spinlock_t job_lock;90 struct list_head callback_jobs;91 struct list_head complete_jobs;92 struct list_head io_jobs;93 struct list_head pages_jobs;94};95 96static struct page_list zero_page_list;97 98static DEFINE_SPINLOCK(throttle_spinlock);99 100/*101 * IO/IDLE accounting slowly decays after (1 << ACCOUNT_INTERVAL_SHIFT) period.102 * When total_period >= (1 << ACCOUNT_INTERVAL_SHIFT) the counters are divided103 * by 2.104 */105#define ACCOUNT_INTERVAL_SHIFT SHIFT_HZ106 107/*108 * Sleep this number of milliseconds.109 *110 * The value was decided experimentally.111 * Smaller values seem to cause an increased copy rate above the limit.112 * The reason for this is unknown but possibly due to jiffies rounding errors113 * or read/write cache inside the disk.114 */115#define SLEEP_USEC 100000116 117/*118 * Maximum number of sleep events. There is a theoretical livelock if more119 * kcopyd clients do work simultaneously which this limit avoids.120 */121#define MAX_SLEEPS 10122 123static void io_job_start(struct dm_kcopyd_throttle *t)124{125 unsigned int throttle, now, difference;126 int slept = 0, skew;127 128 if (unlikely(!t))129 return;130 131try_again:132 spin_lock_irq(&throttle_spinlock);133 134 throttle = READ_ONCE(t->throttle);135 136 if (likely(throttle >= 100))137 goto skip_limit;138 139 now = jiffies;140 difference = now - t->last_jiffies;141 t->last_jiffies = now;142 if (t->num_io_jobs)143 t->io_period += difference;144 t->total_period += difference;145 146 /*147 * Maintain sane values if we got a temporary overflow.148 */149 if (unlikely(t->io_period > t->total_period))150 t->io_period = t->total_period;151 152 if (unlikely(t->total_period >= (1 << ACCOUNT_INTERVAL_SHIFT))) {153 int shift = fls(t->total_period >> ACCOUNT_INTERVAL_SHIFT);154 155 t->total_period >>= shift;156 t->io_period >>= shift;157 }158 159 skew = t->io_period - throttle * t->total_period / 100;160 161 if (unlikely(skew > 0) && slept < MAX_SLEEPS) {162 slept++;163 spin_unlock_irq(&throttle_spinlock);164 fsleep(SLEEP_USEC);165 goto try_again;166 }167 168skip_limit:169 t->num_io_jobs++;170 171 spin_unlock_irq(&throttle_spinlock);172}173 174static void io_job_finish(struct dm_kcopyd_throttle *t)175{176 unsigned long flags;177 178 if (unlikely(!t))179 return;180 181 spin_lock_irqsave(&throttle_spinlock, flags);182 183 t->num_io_jobs--;184 185 if (likely(READ_ONCE(t->throttle) >= 100))186 goto skip_limit;187 188 if (!t->num_io_jobs) {189 unsigned int now, difference;190 191 now = jiffies;192 difference = now - t->last_jiffies;193 t->last_jiffies = now;194 195 t->io_period += difference;196 t->total_period += difference;197 198 /*199 * Maintain sane values if we got a temporary overflow.200 */201 if (unlikely(t->io_period > t->total_period))202 t->io_period = t->total_period;203 }204 205skip_limit:206 spin_unlock_irqrestore(&throttle_spinlock, flags);207}208 209 210static void wake(struct dm_kcopyd_client *kc)211{212 queue_work(kc->kcopyd_wq, &kc->kcopyd_work);213}214 215/*216 * Obtain one page for the use of kcopyd.217 */218static struct page_list *alloc_pl(gfp_t gfp)219{220 struct page_list *pl;221 222 pl = kmalloc(sizeof(*pl), gfp);223 if (!pl)224 return NULL;225 226 pl->page = alloc_page(gfp | __GFP_HIGHMEM);227 if (!pl->page) {228 kfree(pl);229 return NULL;230 }231 232 return pl;233}234 235static void free_pl(struct page_list *pl)236{237 __free_page(pl->page);238 kfree(pl);239}240 241/*242 * Add the provided pages to a client's free page list, releasing243 * back to the system any beyond the reserved_pages limit.244 */245static void kcopyd_put_pages(struct dm_kcopyd_client *kc, struct page_list *pl)246{247 struct page_list *next;248 249 do {250 next = pl->next;251 252 if (kc->nr_free_pages >= kc->nr_reserved_pages)253 free_pl(pl);254 else {255 pl->next = kc->pages;256 kc->pages = pl;257 kc->nr_free_pages++;258 }259 260 pl = next;261 } while (pl);262}263 264static int kcopyd_get_pages(struct dm_kcopyd_client *kc,265 unsigned int nr, struct page_list **pages)266{267 struct page_list *pl;268 269 *pages = NULL;270 271 do {272 pl = alloc_pl(__GFP_NOWARN | __GFP_NORETRY | __GFP_KSWAPD_RECLAIM);273 if (unlikely(!pl)) {274 /* Use reserved pages */275 pl = kc->pages;276 if (unlikely(!pl))277 goto out_of_memory;278 kc->pages = pl->next;279 kc->nr_free_pages--;280 }281 pl->next = *pages;282 *pages = pl;283 } while (--nr);284 285 return 0;286 287out_of_memory:288 if (*pages)289 kcopyd_put_pages(kc, *pages);290 return -ENOMEM;291}292 293/*294 * These three functions resize the page pool.295 */296static void drop_pages(struct page_list *pl)297{298 struct page_list *next;299 300 while (pl) {301 next = pl->next;302 free_pl(pl);303 pl = next;304 }305}306 307/*308 * Allocate and reserve nr_pages for the use of a specific client.309 */310static int client_reserve_pages(struct dm_kcopyd_client *kc, unsigned int nr_pages)311{312 unsigned int i;313 struct page_list *pl = NULL, *next;314 315 for (i = 0; i < nr_pages; i++) {316 next = alloc_pl(GFP_KERNEL);317 if (!next) {318 if (pl)319 drop_pages(pl);320 return -ENOMEM;321 }322 next->next = pl;323 pl = next;324 }325 326 kc->nr_reserved_pages += nr_pages;327 kcopyd_put_pages(kc, pl);328 329 return 0;330}331 332static void client_free_pages(struct dm_kcopyd_client *kc)333{334 BUG_ON(kc->nr_free_pages != kc->nr_reserved_pages);335 drop_pages(kc->pages);336 kc->pages = NULL;337 kc->nr_free_pages = kc->nr_reserved_pages = 0;338}339 340/*341 *---------------------------------------------------------------342 * kcopyd_jobs need to be allocated by the *clients* of kcopyd,343 * for this reason we use a mempool to prevent the client from344 * ever having to do io (which could cause a deadlock).345 *---------------------------------------------------------------346 */347struct kcopyd_job {348 struct dm_kcopyd_client *kc;349 struct list_head list;350 unsigned int flags;351 352 /*353 * Error state of the job.354 */355 int read_err;356 unsigned long write_err;357 358 /*359 * REQ_OP_READ, REQ_OP_WRITE or REQ_OP_WRITE_ZEROES.360 */361 enum req_op op;362 struct dm_io_region source;363 364 /*365 * The destinations for the transfer.366 */367 unsigned int num_dests;368 struct dm_io_region dests[DM_KCOPYD_MAX_REGIONS];369 370 struct page_list *pages;371 372 /*373 * Set this to ensure you are notified when the job has374 * completed. 'context' is for callback to use.375 */376 dm_kcopyd_notify_fn fn;377 void *context;378 379 /*380 * These fields are only used if the job has been split381 * into more manageable parts.382 */383 struct mutex lock;384 atomic_t sub_jobs;385 sector_t progress;386 sector_t write_offset;387 388 struct kcopyd_job *master_job;389};390 391static struct kmem_cache *_job_cache;392 393int __init dm_kcopyd_init(void)394{395 _job_cache = kmem_cache_create("kcopyd_job",396 sizeof(struct kcopyd_job) * (SPLIT_COUNT + 1),397 __alignof__(struct kcopyd_job), 0, NULL);398 if (!_job_cache)399 return -ENOMEM;400 401 zero_page_list.next = &zero_page_list;402 zero_page_list.page = ZERO_PAGE(0);403 404 return 0;405}406 407void dm_kcopyd_exit(void)408{409 kmem_cache_destroy(_job_cache);410 _job_cache = NULL;411}412 413/*414 * Functions to push and pop a job onto the head of a given job415 * list.416 */417static struct kcopyd_job *pop_io_job(struct list_head *jobs,418 struct dm_kcopyd_client *kc)419{420 struct kcopyd_job *job;421 422 /*423 * For I/O jobs, pop any read, any write without sequential write424 * constraint and sequential writes that are at the right position.425 */426 list_for_each_entry(job, jobs, list) {427 if (job->op == REQ_OP_READ ||428 !(job->flags & BIT(DM_KCOPYD_WRITE_SEQ))) {429 list_del(&job->list);430 return job;431 }432 433 if (job->write_offset == job->master_job->write_offset) {434 job->master_job->write_offset += job->source.count;435 list_del(&job->list);436 return job;437 }438 }439 440 return NULL;441}442 443static struct kcopyd_job *pop(struct list_head *jobs,444 struct dm_kcopyd_client *kc)445{446 struct kcopyd_job *job = NULL;447 448 spin_lock_irq(&kc->job_lock);449 450 if (!list_empty(jobs)) {451 if (jobs == &kc->io_jobs)452 job = pop_io_job(jobs, kc);453 else {454 job = list_entry(jobs->next, struct kcopyd_job, list);455 list_del(&job->list);456 }457 }458 spin_unlock_irq(&kc->job_lock);459 460 return job;461}462 463static void push(struct list_head *jobs, struct kcopyd_job *job)464{465 unsigned long flags;466 struct dm_kcopyd_client *kc = job->kc;467 468 spin_lock_irqsave(&kc->job_lock, flags);469 list_add_tail(&job->list, jobs);470 spin_unlock_irqrestore(&kc->job_lock, flags);471}472 473 474static void push_head(struct list_head *jobs, struct kcopyd_job *job)475{476 struct dm_kcopyd_client *kc = job->kc;477 478 spin_lock_irq(&kc->job_lock);479 list_add(&job->list, jobs);480 spin_unlock_irq(&kc->job_lock);481}482 483/*484 * These three functions process 1 item from the corresponding485 * job list.486 *487 * They return:488 * < 0: error489 * 0: success490 * > 0: can't process yet.491 */492static int run_complete_job(struct kcopyd_job *job)493{494 void *context = job->context;495 int read_err = job->read_err;496 unsigned long write_err = job->write_err;497 dm_kcopyd_notify_fn fn = job->fn;498 struct dm_kcopyd_client *kc = job->kc;499 500 if (job->pages && job->pages != &zero_page_list)501 kcopyd_put_pages(kc, job->pages);502 /*503 * If this is the master job, the sub jobs have already504 * completed so we can free everything.505 */506 if (job->master_job == job) {507 mutex_destroy(&job->lock);508 mempool_free(job, &kc->job_pool);509 }510 fn(read_err, write_err, context);511 512 if (atomic_dec_and_test(&kc->nr_jobs))513 wake_up(&kc->destroyq);514 515 cond_resched();516 517 return 0;518}519 520static void complete_io(unsigned long error, void *context)521{522 struct kcopyd_job *job = context;523 struct dm_kcopyd_client *kc = job->kc;524 525 io_job_finish(kc->throttle);526 527 if (error) {528 if (op_is_write(job->op))529 job->write_err |= error;530 else531 job->read_err = 1;532 533 if (!(job->flags & BIT(DM_KCOPYD_IGNORE_ERROR))) {534 push(&kc->complete_jobs, job);535 wake(kc);536 return;537 }538 }539 540 if (op_is_write(job->op))541 push(&kc->complete_jobs, job);542 543 else {544 job->op = REQ_OP_WRITE;545 push(&kc->io_jobs, job);546 }547 548 wake(kc);549}550 551/*552 * Request io on as many buffer heads as we can currently get for553 * a particular job.554 */555static int run_io_job(struct kcopyd_job *job)556{557 int r;558 struct dm_io_request io_req = {559 .bi_opf = job->op,560 .mem.type = DM_IO_PAGE_LIST,561 .mem.ptr.pl = job->pages,562 .mem.offset = 0,563 .notify.fn = complete_io,564 .notify.context = job,565 .client = job->kc->io_client,566 };567 568 /*569 * If we need to write sequentially and some reads or writes failed,570 * no point in continuing.571 */572 if (job->flags & BIT(DM_KCOPYD_WRITE_SEQ) &&573 job->master_job->write_err) {574 job->write_err = job->master_job->write_err;575 return -EIO;576 }577 578 io_job_start(job->kc->throttle);579 580 if (job->op == REQ_OP_READ)581 r = dm_io(&io_req, 1, &job->source, NULL, IOPRIO_DEFAULT);582 else583 r = dm_io(&io_req, job->num_dests, job->dests, NULL, IOPRIO_DEFAULT);584 585 return r;586}587 588static int run_pages_job(struct kcopyd_job *job)589{590 int r;591 unsigned int nr_pages = dm_div_up(job->dests[0].count, PAGE_SIZE >> 9);592 593 r = kcopyd_get_pages(job->kc, nr_pages, &job->pages);594 if (!r) {595 /* this job is ready for io */596 push(&job->kc->io_jobs, job);597 return 0;598 }599 600 if (r == -ENOMEM)601 /* can't complete now */602 return 1;603 604 return r;605}606 607/*608 * Run through a list for as long as possible. Returns the count609 * of successful jobs.610 */611static int process_jobs(struct list_head *jobs, struct dm_kcopyd_client *kc,612 int (*fn)(struct kcopyd_job *))613{614 struct kcopyd_job *job;615 int r, count = 0;616 617 while ((job = pop(jobs, kc))) {618 619 r = fn(job);620 621 if (r < 0) {622 /* error this rogue job */623 if (op_is_write(job->op))624 job->write_err = (unsigned long) -1L;625 else626 job->read_err = 1;627 push(&kc->complete_jobs, job);628 wake(kc);629 break;630 }631 632 if (r > 0) {633 /*634 * We couldn't service this job ATM, so635 * push this job back onto the list.636 */637 push_head(jobs, job);638 break;639 }640 641 count++;642 }643 644 return count;645}646 647/*648 * kcopyd does this every time it's woken up.649 */650static void do_work(struct work_struct *work)651{652 struct dm_kcopyd_client *kc = container_of(work,653 struct dm_kcopyd_client, kcopyd_work);654 struct blk_plug plug;655 656 /*657 * The order that these are called is *very* important.658 * complete jobs can free some pages for pages jobs.659 * Pages jobs when successful will jump onto the io jobs660 * list. io jobs call wake when they complete and it all661 * starts again.662 */663 spin_lock_irq(&kc->job_lock);664 list_splice_tail_init(&kc->callback_jobs, &kc->complete_jobs);665 spin_unlock_irq(&kc->job_lock);666 667 blk_start_plug(&plug);668 process_jobs(&kc->complete_jobs, kc, run_complete_job);669 process_jobs(&kc->pages_jobs, kc, run_pages_job);670 process_jobs(&kc->io_jobs, kc, run_io_job);671 blk_finish_plug(&plug);672}673 674/*675 * If we are copying a small region we just dispatch a single job676 * to do the copy, otherwise the io has to be split up into many677 * jobs.678 */679static void dispatch_job(struct kcopyd_job *job)680{681 struct dm_kcopyd_client *kc = job->kc;682 683 atomic_inc(&kc->nr_jobs);684 if (unlikely(!job->source.count))685 push(&kc->callback_jobs, job);686 else if (job->pages == &zero_page_list)687 push(&kc->io_jobs, job);688 else689 push(&kc->pages_jobs, job);690 wake(kc);691}692 693static void segment_complete(int read_err, unsigned long write_err,694 void *context)695{696 /* FIXME: tidy this function */697 sector_t progress = 0;698 sector_t count = 0;699 struct kcopyd_job *sub_job = context;700 struct kcopyd_job *job = sub_job->master_job;701 struct dm_kcopyd_client *kc = job->kc;702 703 mutex_lock(&job->lock);704 705 /* update the error */706 if (read_err)707 job->read_err = 1;708 709 if (write_err)710 job->write_err |= write_err;711 712 /*713 * Only dispatch more work if there hasn't been an error.714 */715 if ((!job->read_err && !job->write_err) ||716 job->flags & BIT(DM_KCOPYD_IGNORE_ERROR)) {717 /* get the next chunk of work */718 progress = job->progress;719 count = job->source.count - progress;720 if (count) {721 if (count > kc->sub_job_size)722 count = kc->sub_job_size;723 724 job->progress += count;725 }726 }727 mutex_unlock(&job->lock);728 729 if (count) {730 int i;731 732 *sub_job = *job;733 sub_job->write_offset = progress;734 sub_job->source.sector += progress;735 sub_job->source.count = count;736 737 for (i = 0; i < job->num_dests; i++) {738 sub_job->dests[i].sector += progress;739 sub_job->dests[i].count = count;740 }741 742 sub_job->fn = segment_complete;743 sub_job->context = sub_job;744 dispatch_job(sub_job);745 746 } else if (atomic_dec_and_test(&job->sub_jobs)) {747 748 /*749 * Queue the completion callback to the kcopyd thread.750 *751 * Some callers assume that all the completions are called752 * from a single thread and don't race with each other.753 *754 * We must not call the callback directly here because this755 * code may not be executing in the thread.756 */757 push(&kc->complete_jobs, job);758 wake(kc);759 }760}761 762/*763 * Create some sub jobs to share the work between them.764 */765static void split_job(struct kcopyd_job *master_job)766{767 int i;768 769 atomic_inc(&master_job->kc->nr_jobs);770 771 atomic_set(&master_job->sub_jobs, SPLIT_COUNT);772 for (i = 0; i < SPLIT_COUNT; i++) {773 master_job[i + 1].master_job = master_job;774 segment_complete(0, 0u, &master_job[i + 1]);775 }776}777 778void dm_kcopyd_copy(struct dm_kcopyd_client *kc, struct dm_io_region *from,779 unsigned int num_dests, struct dm_io_region *dests,780 unsigned int flags, dm_kcopyd_notify_fn fn, void *context)781{782 struct kcopyd_job *job;783 int i;784 785 /*786 * Allocate an array of jobs consisting of one master job787 * followed by SPLIT_COUNT sub jobs.788 */789 job = mempool_alloc(&kc->job_pool, GFP_NOIO);790 mutex_init(&job->lock);791 792 /*793 * set up for the read.794 */795 job->kc = kc;796 job->flags = flags;797 job->read_err = 0;798 job->write_err = 0;799 800 job->num_dests = num_dests;801 memcpy(&job->dests, dests, sizeof(*dests) * num_dests);802 803 /*804 * If one of the destination is a host-managed zoned block device,805 * we need to write sequentially. If one of the destination is a806 * host-aware device, then leave it to the caller to choose what to do.807 */808 if (!(job->flags & BIT(DM_KCOPYD_WRITE_SEQ))) {809 for (i = 0; i < job->num_dests; i++) {810 if (bdev_is_zoned(dests[i].bdev)) {811 job->flags |= BIT(DM_KCOPYD_WRITE_SEQ);812 break;813 }814 }815 }816 817 /*818 * If we need to write sequentially, errors cannot be ignored.819 */820 if (job->flags & BIT(DM_KCOPYD_WRITE_SEQ) &&821 job->flags & BIT(DM_KCOPYD_IGNORE_ERROR))822 job->flags &= ~BIT(DM_KCOPYD_IGNORE_ERROR);823 824 if (from) {825 job->source = *from;826 job->pages = NULL;827 job->op = REQ_OP_READ;828 } else {829 memset(&job->source, 0, sizeof(job->source));830 job->source.count = job->dests[0].count;831 job->pages = &zero_page_list;832 833 /*834 * Use WRITE ZEROES to optimize zeroing if all dests support it.835 */836 job->op = REQ_OP_WRITE_ZEROES;837 for (i = 0; i < job->num_dests; i++)838 if (!bdev_write_zeroes_sectors(job->dests[i].bdev)) {839 job->op = REQ_OP_WRITE;840 break;841 }842 }843 844 job->fn = fn;845 job->context = context;846 job->master_job = job;847 job->write_offset = 0;848 849 if (job->source.count <= kc->sub_job_size)850 dispatch_job(job);851 else {852 job->progress = 0;853 split_job(job);854 }855}856EXPORT_SYMBOL(dm_kcopyd_copy);857 858void dm_kcopyd_zero(struct dm_kcopyd_client *kc,859 unsigned int num_dests, struct dm_io_region *dests,860 unsigned int flags, dm_kcopyd_notify_fn fn, void *context)861{862 dm_kcopyd_copy(kc, NULL, num_dests, dests, flags, fn, context);863}864EXPORT_SYMBOL(dm_kcopyd_zero);865 866void *dm_kcopyd_prepare_callback(struct dm_kcopyd_client *kc,867 dm_kcopyd_notify_fn fn, void *context)868{869 struct kcopyd_job *job;870 871 job = mempool_alloc(&kc->job_pool, GFP_NOIO);872 873 memset(job, 0, sizeof(struct kcopyd_job));874 job->kc = kc;875 job->fn = fn;876 job->context = context;877 job->master_job = job;878 879 atomic_inc(&kc->nr_jobs);880 881 return job;882}883EXPORT_SYMBOL(dm_kcopyd_prepare_callback);884 885void dm_kcopyd_do_callback(void *j, int read_err, unsigned long write_err)886{887 struct kcopyd_job *job = j;888 struct dm_kcopyd_client *kc = job->kc;889 890 job->read_err = read_err;891 job->write_err = write_err;892 893 push(&kc->callback_jobs, job);894 wake(kc);895}896EXPORT_SYMBOL(dm_kcopyd_do_callback);897 898/*899 * Cancels a kcopyd job, eg. someone might be deactivating a900 * mirror.901 */902#if 0903int kcopyd_cancel(struct kcopyd_job *job, int block)904{905 /* FIXME: finish */906 return -1;907}908#endif /* 0 */909 910/*911 *---------------------------------------------------------------912 * Client setup913 *---------------------------------------------------------------914 */915struct dm_kcopyd_client *dm_kcopyd_client_create(struct dm_kcopyd_throttle *throttle)916{917 int r;918 unsigned int reserve_pages;919 struct dm_kcopyd_client *kc;920 921 kc = kzalloc(sizeof(*kc), GFP_KERNEL);922 if (!kc)923 return ERR_PTR(-ENOMEM);924 925 spin_lock_init(&kc->job_lock);926 INIT_LIST_HEAD(&kc->callback_jobs);927 INIT_LIST_HEAD(&kc->complete_jobs);928 INIT_LIST_HEAD(&kc->io_jobs);929 INIT_LIST_HEAD(&kc->pages_jobs);930 kc->throttle = throttle;931 932 r = mempool_init_slab_pool(&kc->job_pool, MIN_JOBS, _job_cache);933 if (r)934 goto bad_slab;935 936 INIT_WORK(&kc->kcopyd_work, do_work);937 kc->kcopyd_wq = alloc_workqueue("kcopyd", WQ_MEM_RECLAIM, 0);938 if (!kc->kcopyd_wq) {939 r = -ENOMEM;940 goto bad_workqueue;941 }942 943 kc->sub_job_size = dm_get_kcopyd_subjob_size();944 reserve_pages = DIV_ROUND_UP(kc->sub_job_size << SECTOR_SHIFT, PAGE_SIZE);945 946 kc->pages = NULL;947 kc->nr_reserved_pages = kc->nr_free_pages = 0;948 r = client_reserve_pages(kc, reserve_pages);949 if (r)950 goto bad_client_pages;951 952 kc->io_client = dm_io_client_create();953 if (IS_ERR(kc->io_client)) {954 r = PTR_ERR(kc->io_client);955 goto bad_io_client;956 }957 958 init_waitqueue_head(&kc->destroyq);959 atomic_set(&kc->nr_jobs, 0);960 961 return kc;962 963bad_io_client:964 client_free_pages(kc);965bad_client_pages:966 destroy_workqueue(kc->kcopyd_wq);967bad_workqueue:968 mempool_exit(&kc->job_pool);969bad_slab:970 kfree(kc);971 972 return ERR_PTR(r);973}974EXPORT_SYMBOL(dm_kcopyd_client_create);975 976void dm_kcopyd_client_destroy(struct dm_kcopyd_client *kc)977{978 /* Wait for completion of all jobs submitted by this client. */979 wait_event(kc->destroyq, !atomic_read(&kc->nr_jobs));980 981 BUG_ON(!list_empty(&kc->callback_jobs));982 BUG_ON(!list_empty(&kc->complete_jobs));983 BUG_ON(!list_empty(&kc->io_jobs));984 BUG_ON(!list_empty(&kc->pages_jobs));985 destroy_workqueue(kc->kcopyd_wq);986 dm_io_client_destroy(kc->io_client);987 client_free_pages(kc);988 mempool_exit(&kc->job_pool);989 kfree(kc);990}991EXPORT_SYMBOL(dm_kcopyd_client_destroy);992 993void dm_kcopyd_client_flush(struct dm_kcopyd_client *kc)994{995 flush_workqueue(kc->kcopyd_wq);996}997EXPORT_SYMBOL(dm_kcopyd_client_flush);998