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1/*
2 * Copyright (C) 2002 Sistina Software (UK) Limited.
3 * Copyright (C) 2006 Red Hat GmbH
4 *
5 * This file is released under the GPL.
6 *
7 * Kcopyd provides a simple interface for copying an area of one
8 * block-device to one or more other block-devices, with an asynchronous
9 * completion notification.
10 */
11
12#include <linux/types.h>
13#include <linux/atomic.h>
14#include <linux/blkdev.h>
15#include <linux/fs.h>
16#include <linux/init.h>
17#include <linux/list.h>
18#include <linux/mempool.h>
19#include <linux/module.h>
20#include <linux/pagemap.h>
21#include <linux/slab.h>
22#include <linux/vmalloc.h>
23#include <linux/workqueue.h>
24#include <linux/mutex.h>
25#include <linux/delay.h>
26#include <linux/device-mapper.h>
27#include <linux/dm-kcopyd.h>
28
29#include "dm-core.h"
30
31#define SPLIT_COUNT 8
32#define MIN_JOBS 8
33
34#define DEFAULT_SUB_JOB_SIZE_KB 512
35#define MAX_SUB_JOB_SIZE_KB 1024
36
37static unsigned kcopyd_subjob_size_kb = DEFAULT_SUB_JOB_SIZE_KB;
38
39module_param(kcopyd_subjob_size_kb, uint, S_IRUGO | S_IWUSR);
40MODULE_PARM_DESC(kcopyd_subjob_size_kb, "Sub-job size for dm-kcopyd clients");
41
42static unsigned dm_get_kcopyd_subjob_size(void)
43{
44 unsigned sub_job_size_kb;
45
46 sub_job_size_kb = __dm_get_module_param(&kcopyd_subjob_size_kb,
47 DEFAULT_SUB_JOB_SIZE_KB,
48 MAX_SUB_JOB_SIZE_KB);
49
50 return sub_job_size_kb << 1;
51}
52
53/*-----------------------------------------------------------------
54 * Each kcopyd client has its own little pool of preallocated
55 * pages for kcopyd io.
56 *---------------------------------------------------------------*/
57struct dm_kcopyd_client {
58 struct page_list *pages;
59 unsigned nr_reserved_pages;
60 unsigned nr_free_pages;
61 unsigned sub_job_size;
62
63 struct dm_io_client *io_client;
64
65 wait_queue_head_t destroyq;
66
67 mempool_t job_pool;
68
69 struct workqueue_struct *kcopyd_wq;
70 struct work_struct kcopyd_work;
71
72 struct dm_kcopyd_throttle *throttle;
73
74 atomic_t nr_jobs;
75
76/*
77 * We maintain four lists of jobs:
78 *
79 * i) jobs waiting for pages
80 * ii) jobs that have pages, and are waiting for the io to be issued.
81 * iii) jobs that don't need to do any IO and just run a callback
82 * iv) jobs that have completed.
83 *
84 * All four of these are protected by job_lock.
85 */
86 spinlock_t job_lock;
87 struct list_head callback_jobs;
88 struct list_head complete_jobs;
89 struct list_head io_jobs;
90 struct list_head pages_jobs;
91};
92
93static struct page_list zero_page_list;
94
95static DEFINE_SPINLOCK(throttle_spinlock);
96
97/*
98 * IO/IDLE accounting slowly decays after (1 << ACCOUNT_INTERVAL_SHIFT) period.
99 * When total_period >= (1 << ACCOUNT_INTERVAL_SHIFT) the counters are divided
100 * by 2.
101 */
102#define ACCOUNT_INTERVAL_SHIFT SHIFT_HZ
103
104/*
105 * Sleep this number of milliseconds.
106 *
107 * The value was decided experimentally.
108 * Smaller values seem to cause an increased copy rate above the limit.
109 * The reason for this is unknown but possibly due to jiffies rounding errors
110 * or read/write cache inside the disk.
111 */
112#define SLEEP_MSEC 100
113
114/*
115 * Maximum number of sleep events. There is a theoretical livelock if more
116 * kcopyd clients do work simultaneously which this limit avoids.
117 */
118#define MAX_SLEEPS 10
119
120static void io_job_start(struct dm_kcopyd_throttle *t)
121{
122 unsigned throttle, now, difference;
123 int slept = 0, skew;
124
125 if (unlikely(!t))
126 return;
127
128try_again:
129 spin_lock_irq(&throttle_spinlock);
130
131 throttle = READ_ONCE(t->throttle);
132
133 if (likely(throttle >= 100))
134 goto skip_limit;
135
136 now = jiffies;
137 difference = now - t->last_jiffies;
138 t->last_jiffies = now;
139 if (t->num_io_jobs)
140 t->io_period += difference;
141 t->total_period += difference;
142
143 /*
144 * Maintain sane values if we got a temporary overflow.
145 */
146 if (unlikely(t->io_period > t->total_period))
147 t->io_period = t->total_period;
148
149 if (unlikely(t->total_period >= (1 << ACCOUNT_INTERVAL_SHIFT))) {
150 int shift = fls(t->total_period >> ACCOUNT_INTERVAL_SHIFT);
151 t->total_period >>= shift;
152 t->io_period >>= shift;
153 }
154
155 skew = t->io_period - throttle * t->total_period / 100;
156
157 if (unlikely(skew > 0) && slept < MAX_SLEEPS) {
158 slept++;
159 spin_unlock_irq(&throttle_spinlock);
160 msleep(SLEEP_MSEC);
161 goto try_again;
162 }
163
164skip_limit:
165 t->num_io_jobs++;
166
167 spin_unlock_irq(&throttle_spinlock);
168}
169
170static void io_job_finish(struct dm_kcopyd_throttle *t)
171{
172 unsigned long flags;
173
174 if (unlikely(!t))
175 return;
176
177 spin_lock_irqsave(&throttle_spinlock, flags);
178
179 t->num_io_jobs--;
180
181 if (likely(READ_ONCE(t->throttle) >= 100))
182 goto skip_limit;
183
184 if (!t->num_io_jobs) {
185 unsigned now, difference;
186
187 now = jiffies;
188 difference = now - t->last_jiffies;
189 t->last_jiffies = now;
190
191 t->io_period += difference;
192 t->total_period += difference;
193
194 /*
195 * Maintain sane values if we got a temporary overflow.
196 */
197 if (unlikely(t->io_period > t->total_period))
198 t->io_period = t->total_period;
199 }
200
201skip_limit:
202 spin_unlock_irqrestore(&throttle_spinlock, flags);
203}
204
205
206static void wake(struct dm_kcopyd_client *kc)
207{
208 queue_work(kc->kcopyd_wq, &kc->kcopyd_work);
209}
210
211/*
212 * Obtain one page for the use of kcopyd.
213 */
214static struct page_list *alloc_pl(gfp_t gfp)
215{
216 struct page_list *pl;
217
218 pl = kmalloc(sizeof(*pl), gfp);
219 if (!pl)
220 return NULL;
221
222 pl->page = alloc_page(gfp | __GFP_HIGHMEM);
223 if (!pl->page) {
224 kfree(pl);
225 return NULL;
226 }
227
228 return pl;
229}
230
231static void free_pl(struct page_list *pl)
232{
233 __free_page(pl->page);
234 kfree(pl);
235}
236
237/*
238 * Add the provided pages to a client's free page list, releasing
239 * back to the system any beyond the reserved_pages limit.
240 */
241static void kcopyd_put_pages(struct dm_kcopyd_client *kc, struct page_list *pl)
242{
243 struct page_list *next;
244
245 do {
246 next = pl->next;
247
248 if (kc->nr_free_pages >= kc->nr_reserved_pages)
249 free_pl(pl);
250 else {
251 pl->next = kc->pages;
252 kc->pages = pl;
253 kc->nr_free_pages++;
254 }
255
256 pl = next;
257 } while (pl);
258}
259
260static int kcopyd_get_pages(struct dm_kcopyd_client *kc,
261 unsigned int nr, struct page_list **pages)
262{
263 struct page_list *pl;
264
265 *pages = NULL;
266
267 do {
268 pl = alloc_pl(__GFP_NOWARN | __GFP_NORETRY | __GFP_KSWAPD_RECLAIM);
269 if (unlikely(!pl)) {
270 /* Use reserved pages */
271 pl = kc->pages;
272 if (unlikely(!pl))
273 goto out_of_memory;
274 kc->pages = pl->next;
275 kc->nr_free_pages--;
276 }
277 pl->next = *pages;
278 *pages = pl;
279 } while (--nr);
280
281 return 0;
282
283out_of_memory:
284 if (*pages)
285 kcopyd_put_pages(kc, *pages);
286 return -ENOMEM;
287}
288
289/*
290 * These three functions resize the page pool.
291 */
292static void drop_pages(struct page_list *pl)
293{
294 struct page_list *next;
295
296 while (pl) {
297 next = pl->next;
298 free_pl(pl);
299 pl = next;
300 }
301}
302
303/*
304 * Allocate and reserve nr_pages for the use of a specific client.
305 */
306static int client_reserve_pages(struct dm_kcopyd_client *kc, unsigned nr_pages)
307{
308 unsigned i;
309 struct page_list *pl = NULL, *next;
310
311 for (i = 0; i < nr_pages; i++) {
312 next = alloc_pl(GFP_KERNEL);
313 if (!next) {
314 if (pl)
315 drop_pages(pl);
316 return -ENOMEM;
317 }
318 next->next = pl;
319 pl = next;
320 }
321
322 kc->nr_reserved_pages += nr_pages;
323 kcopyd_put_pages(kc, pl);
324
325 return 0;
326}
327
328static void client_free_pages(struct dm_kcopyd_client *kc)
329{
330 BUG_ON(kc->nr_free_pages != kc->nr_reserved_pages);
331 drop_pages(kc->pages);
332 kc->pages = NULL;
333 kc->nr_free_pages = kc->nr_reserved_pages = 0;
334}
335
336/*-----------------------------------------------------------------
337 * kcopyd_jobs need to be allocated by the *clients* of kcopyd,
338 * for this reason we use a mempool to prevent the client from
339 * ever having to do io (which could cause a deadlock).
340 *---------------------------------------------------------------*/
341struct kcopyd_job {
342 struct dm_kcopyd_client *kc;
343 struct list_head list;
344 unsigned flags;
345
346 /*
347 * Error state of the job.
348 */
349 int read_err;
350 unsigned long write_err;
351
352 /*
353 * REQ_OP_READ, REQ_OP_WRITE or REQ_OP_WRITE_ZEROES.
354 */
355 enum req_op op;
356 struct dm_io_region source;
357
358 /*
359 * The destinations for the transfer.
360 */
361 unsigned int num_dests;
362 struct dm_io_region dests[DM_KCOPYD_MAX_REGIONS];
363
364 struct page_list *pages;
365
366 /*
367 * Set this to ensure you are notified when the job has
368 * completed. 'context' is for callback to use.
369 */
370 dm_kcopyd_notify_fn fn;
371 void *context;
372
373 /*
374 * These fields are only used if the job has been split
375 * into more manageable parts.
376 */
377 struct mutex lock;
378 atomic_t sub_jobs;
379 sector_t progress;
380 sector_t write_offset;
381
382 struct kcopyd_job *master_job;
383};
384
385static struct kmem_cache *_job_cache;
386
387int __init dm_kcopyd_init(void)
388{
389 _job_cache = kmem_cache_create("kcopyd_job",
390 sizeof(struct kcopyd_job) * (SPLIT_COUNT + 1),
391 __alignof__(struct kcopyd_job), 0, NULL);
392 if (!_job_cache)
393 return -ENOMEM;
394
395 zero_page_list.next = &zero_page_list;
396 zero_page_list.page = ZERO_PAGE(0);
397
398 return 0;
399}
400
401void dm_kcopyd_exit(void)
402{
403 kmem_cache_destroy(_job_cache);
404 _job_cache = NULL;
405}
406
407/*
408 * Functions to push and pop a job onto the head of a given job
409 * list.
410 */
411static struct kcopyd_job *pop_io_job(struct list_head *jobs,
412 struct dm_kcopyd_client *kc)
413{
414 struct kcopyd_job *job;
415
416 /*
417 * For I/O jobs, pop any read, any write without sequential write
418 * constraint and sequential writes that are at the right position.
419 */
420 list_for_each_entry(job, jobs, list) {
421 if (job->op == REQ_OP_READ ||
422 !(job->flags & BIT(DM_KCOPYD_WRITE_SEQ))) {
423 list_del(&job->list);
424 return job;
425 }
426
427 if (job->write_offset == job->master_job->write_offset) {
428 job->master_job->write_offset += job->source.count;
429 list_del(&job->list);
430 return job;
431 }
432 }
433
434 return NULL;
435}
436
437static struct kcopyd_job *pop(struct list_head *jobs,
438 struct dm_kcopyd_client *kc)
439{
440 struct kcopyd_job *job = NULL;
441
442 spin_lock_irq(&kc->job_lock);
443
444 if (!list_empty(jobs)) {
445 if (jobs == &kc->io_jobs)
446 job = pop_io_job(jobs, kc);
447 else {
448 job = list_entry(jobs->next, struct kcopyd_job, list);
449 list_del(&job->list);
450 }
451 }
452 spin_unlock_irq(&kc->job_lock);
453
454 return job;
455}
456
457static void push(struct list_head *jobs, struct kcopyd_job *job)
458{
459 unsigned long flags;
460 struct dm_kcopyd_client *kc = job->kc;
461
462 spin_lock_irqsave(&kc->job_lock, flags);
463 list_add_tail(&job->list, jobs);
464 spin_unlock_irqrestore(&kc->job_lock, flags);
465}
466
467
468static void push_head(struct list_head *jobs, struct kcopyd_job *job)
469{
470 struct dm_kcopyd_client *kc = job->kc;
471
472 spin_lock_irq(&kc->job_lock);
473 list_add(&job->list, jobs);
474 spin_unlock_irq(&kc->job_lock);
475}
476
477/*
478 * These three functions process 1 item from the corresponding
479 * job list.
480 *
481 * They return:
482 * < 0: error
483 * 0: success
484 * > 0: can't process yet.
485 */
486static int run_complete_job(struct kcopyd_job *job)
487{
488 void *context = job->context;
489 int read_err = job->read_err;
490 unsigned long write_err = job->write_err;
491 dm_kcopyd_notify_fn fn = job->fn;
492 struct dm_kcopyd_client *kc = job->kc;
493
494 if (job->pages && job->pages != &zero_page_list)
495 kcopyd_put_pages(kc, job->pages);
496 /*
497 * If this is the master job, the sub jobs have already
498 * completed so we can free everything.
499 */
500 if (job->master_job == job) {
501 mutex_destroy(&job->lock);
502 mempool_free(job, &kc->job_pool);
503 }
504 fn(read_err, write_err, context);
505
506 if (atomic_dec_and_test(&kc->nr_jobs))
507 wake_up(&kc->destroyq);
508
509 cond_resched();
510
511 return 0;
512}
513
514static void complete_io(unsigned long error, void *context)
515{
516 struct kcopyd_job *job = (struct kcopyd_job *) context;
517 struct dm_kcopyd_client *kc = job->kc;
518
519 io_job_finish(kc->throttle);
520
521 if (error) {
522 if (op_is_write(job->op))
523 job->write_err |= error;
524 else
525 job->read_err = 1;
526
527 if (!(job->flags & BIT(DM_KCOPYD_IGNORE_ERROR))) {
528 push(&kc->complete_jobs, job);
529 wake(kc);
530 return;
531 }
532 }
533
534 if (op_is_write(job->op))
535 push(&kc->complete_jobs, job);
536
537 else {
538 job->op = REQ_OP_WRITE;
539 push(&kc->io_jobs, job);
540 }
541
542 wake(kc);
543}
544
545/*
546 * Request io on as many buffer heads as we can currently get for
547 * a particular job.
548 */
549static int run_io_job(struct kcopyd_job *job)
550{
551 int r;
552 struct dm_io_request io_req = {
553 .bi_opf = job->op,
554 .mem.type = DM_IO_PAGE_LIST,
555 .mem.ptr.pl = job->pages,
556 .mem.offset = 0,
557 .notify.fn = complete_io,
558 .notify.context = job,
559 .client = job->kc->io_client,
560 };
561
562 /*
563 * If we need to write sequentially and some reads or writes failed,
564 * no point in continuing.
565 */
566 if (job->flags & BIT(DM_KCOPYD_WRITE_SEQ) &&
567 job->master_job->write_err) {
568 job->write_err = job->master_job->write_err;
569 return -EIO;
570 }
571
572 io_job_start(job->kc->throttle);
573
574 if (job->op == REQ_OP_READ)
575 r = dm_io(&io_req, 1, &job->source, NULL);
576 else
577 r = dm_io(&io_req, job->num_dests, job->dests, NULL);
578
579 return r;
580}
581
582static int run_pages_job(struct kcopyd_job *job)
583{
584 int r;
585 unsigned nr_pages = dm_div_up(job->dests[0].count, PAGE_SIZE >> 9);
586
587 r = kcopyd_get_pages(job->kc, nr_pages, &job->pages);
588 if (!r) {
589 /* this job is ready for io */
590 push(&job->kc->io_jobs, job);
591 return 0;
592 }
593
594 if (r == -ENOMEM)
595 /* can't complete now */
596 return 1;
597
598 return r;
599}
600
601/*
602 * Run through a list for as long as possible. Returns the count
603 * of successful jobs.
604 */
605static int process_jobs(struct list_head *jobs, struct dm_kcopyd_client *kc,
606 int (*fn) (struct kcopyd_job *))
607{
608 struct kcopyd_job *job;
609 int r, count = 0;
610
611 while ((job = pop(jobs, kc))) {
612
613 r = fn(job);
614
615 if (r < 0) {
616 /* error this rogue job */
617 if (op_is_write(job->op))
618 job->write_err = (unsigned long) -1L;
619 else
620 job->read_err = 1;
621 push(&kc->complete_jobs, job);
622 wake(kc);
623 break;
624 }
625
626 if (r > 0) {
627 /*
628 * We couldn't service this job ATM, so
629 * push this job back onto the list.
630 */
631 push_head(jobs, job);
632 break;
633 }
634
635 count++;
636 }
637
638 return count;
639}
640
641/*
642 * kcopyd does this every time it's woken up.
643 */
644static void do_work(struct work_struct *work)
645{
646 struct dm_kcopyd_client *kc = container_of(work,
647 struct dm_kcopyd_client, kcopyd_work);
648 struct blk_plug plug;
649
650 /*
651 * The order that these are called is *very* important.
652 * complete jobs can free some pages for pages jobs.
653 * Pages jobs when successful will jump onto the io jobs
654 * list. io jobs call wake when they complete and it all
655 * starts again.
656 */
657 spin_lock_irq(&kc->job_lock);
658 list_splice_tail_init(&kc->callback_jobs, &kc->complete_jobs);
659 spin_unlock_irq(&kc->job_lock);
660
661 blk_start_plug(&plug);
662 process_jobs(&kc->complete_jobs, kc, run_complete_job);
663 process_jobs(&kc->pages_jobs, kc, run_pages_job);
664 process_jobs(&kc->io_jobs, kc, run_io_job);
665 blk_finish_plug(&plug);
666}
667
668/*
669 * If we are copying a small region we just dispatch a single job
670 * to do the copy, otherwise the io has to be split up into many
671 * jobs.
672 */
673static void dispatch_job(struct kcopyd_job *job)
674{
675 struct dm_kcopyd_client *kc = job->kc;
676 atomic_inc(&kc->nr_jobs);
677 if (unlikely(!job->source.count))
678 push(&kc->callback_jobs, job);
679 else if (job->pages == &zero_page_list)
680 push(&kc->io_jobs, job);
681 else
682 push(&kc->pages_jobs, job);
683 wake(kc);
684}
685
686static void segment_complete(int read_err, unsigned long write_err,
687 void *context)
688{
689 /* FIXME: tidy this function */
690 sector_t progress = 0;
691 sector_t count = 0;
692 struct kcopyd_job *sub_job = (struct kcopyd_job *) context;
693 struct kcopyd_job *job = sub_job->master_job;
694 struct dm_kcopyd_client *kc = job->kc;
695
696 mutex_lock(&job->lock);
697
698 /* update the error */
699 if (read_err)
700 job->read_err = 1;
701
702 if (write_err)
703 job->write_err |= write_err;
704
705 /*
706 * Only dispatch more work if there hasn't been an error.
707 */
708 if ((!job->read_err && !job->write_err) ||
709 job->flags & BIT(DM_KCOPYD_IGNORE_ERROR)) {
710 /* get the next chunk of work */
711 progress = job->progress;
712 count = job->source.count - progress;
713 if (count) {
714 if (count > kc->sub_job_size)
715 count = kc->sub_job_size;
716
717 job->progress += count;
718 }
719 }
720 mutex_unlock(&job->lock);
721
722 if (count) {
723 int i;
724
725 *sub_job = *job;
726 sub_job->write_offset = progress;
727 sub_job->source.sector += progress;
728 sub_job->source.count = count;
729
730 for (i = 0; i < job->num_dests; i++) {
731 sub_job->dests[i].sector += progress;
732 sub_job->dests[i].count = count;
733 }
734
735 sub_job->fn = segment_complete;
736 sub_job->context = sub_job;
737 dispatch_job(sub_job);
738
739 } else if (atomic_dec_and_test(&job->sub_jobs)) {
740
741 /*
742 * Queue the completion callback to the kcopyd thread.
743 *
744 * Some callers assume that all the completions are called
745 * from a single thread and don't race with each other.
746 *
747 * We must not call the callback directly here because this
748 * code may not be executing in the thread.
749 */
750 push(&kc->complete_jobs, job);
751 wake(kc);
752 }
753}
754
755/*
756 * Create some sub jobs to share the work between them.
757 */
758static void split_job(struct kcopyd_job *master_job)
759{
760 int i;
761
762 atomic_inc(&master_job->kc->nr_jobs);
763
764 atomic_set(&master_job->sub_jobs, SPLIT_COUNT);
765 for (i = 0; i < SPLIT_COUNT; i++) {
766 master_job[i + 1].master_job = master_job;
767 segment_complete(0, 0u, &master_job[i + 1]);
768 }
769}
770
771void dm_kcopyd_copy(struct dm_kcopyd_client *kc, struct dm_io_region *from,
772 unsigned int num_dests, struct dm_io_region *dests,
773 unsigned int flags, dm_kcopyd_notify_fn fn, void *context)
774{
775 struct kcopyd_job *job;
776 int i;
777
778 /*
779 * Allocate an array of jobs consisting of one master job
780 * followed by SPLIT_COUNT sub jobs.
781 */
782 job = mempool_alloc(&kc->job_pool, GFP_NOIO);
783 mutex_init(&job->lock);
784
785 /*
786 * set up for the read.
787 */
788 job->kc = kc;
789 job->flags = flags;
790 job->read_err = 0;
791 job->write_err = 0;
792
793 job->num_dests = num_dests;
794 memcpy(&job->dests, dests, sizeof(*dests) * num_dests);
795
796 /*
797 * If one of the destination is a host-managed zoned block device,
798 * we need to write sequentially. If one of the destination is a
799 * host-aware device, then leave it to the caller to choose what to do.
800 */
801 if (!(job->flags & BIT(DM_KCOPYD_WRITE_SEQ))) {
802 for (i = 0; i < job->num_dests; i++) {
803 if (bdev_zoned_model(dests[i].bdev) == BLK_ZONED_HM) {
804 job->flags |= BIT(DM_KCOPYD_WRITE_SEQ);
805 break;
806 }
807 }
808 }
809
810 /*
811 * If we need to write sequentially, errors cannot be ignored.
812 */
813 if (job->flags & BIT(DM_KCOPYD_WRITE_SEQ) &&
814 job->flags & BIT(DM_KCOPYD_IGNORE_ERROR))
815 job->flags &= ~BIT(DM_KCOPYD_IGNORE_ERROR);
816
817 if (from) {
818 job->source = *from;
819 job->pages = NULL;
820 job->op = REQ_OP_READ;
821 } else {
822 memset(&job->source, 0, sizeof job->source);
823 job->source.count = job->dests[0].count;
824 job->pages = &zero_page_list;
825
826 /*
827 * Use WRITE ZEROES to optimize zeroing if all dests support it.
828 */
829 job->op = REQ_OP_WRITE_ZEROES;
830 for (i = 0; i < job->num_dests; i++)
831 if (!bdev_write_zeroes_sectors(job->dests[i].bdev)) {
832 job->op = REQ_OP_WRITE;
833 break;
834 }
835 }
836
837 job->fn = fn;
838 job->context = context;
839 job->master_job = job;
840 job->write_offset = 0;
841
842 if (job->source.count <= kc->sub_job_size)
843 dispatch_job(job);
844 else {
845 job->progress = 0;
846 split_job(job);
847 }
848}
849EXPORT_SYMBOL(dm_kcopyd_copy);
850
851void dm_kcopyd_zero(struct dm_kcopyd_client *kc,
852 unsigned num_dests, struct dm_io_region *dests,
853 unsigned flags, dm_kcopyd_notify_fn fn, void *context)
854{
855 dm_kcopyd_copy(kc, NULL, num_dests, dests, flags, fn, context);
856}
857EXPORT_SYMBOL(dm_kcopyd_zero);
858
859void *dm_kcopyd_prepare_callback(struct dm_kcopyd_client *kc,
860 dm_kcopyd_notify_fn fn, void *context)
861{
862 struct kcopyd_job *job;
863
864 job = mempool_alloc(&kc->job_pool, GFP_NOIO);
865
866 memset(job, 0, sizeof(struct kcopyd_job));
867 job->kc = kc;
868 job->fn = fn;
869 job->context = context;
870 job->master_job = job;
871
872 atomic_inc(&kc->nr_jobs);
873
874 return job;
875}
876EXPORT_SYMBOL(dm_kcopyd_prepare_callback);
877
878void dm_kcopyd_do_callback(void *j, int read_err, unsigned long write_err)
879{
880 struct kcopyd_job *job = j;
881 struct dm_kcopyd_client *kc = job->kc;
882
883 job->read_err = read_err;
884 job->write_err = write_err;
885
886 push(&kc->callback_jobs, job);
887 wake(kc);
888}
889EXPORT_SYMBOL(dm_kcopyd_do_callback);
890
891/*
892 * Cancels a kcopyd job, eg. someone might be deactivating a
893 * mirror.
894 */
895#if 0
896int kcopyd_cancel(struct kcopyd_job *job, int block)
897{
898 /* FIXME: finish */
899 return -1;
900}
901#endif /* 0 */
902
903/*-----------------------------------------------------------------
904 * Client setup
905 *---------------------------------------------------------------*/
906struct dm_kcopyd_client *dm_kcopyd_client_create(struct dm_kcopyd_throttle *throttle)
907{
908 int r;
909 unsigned reserve_pages;
910 struct dm_kcopyd_client *kc;
911
912 kc = kzalloc(sizeof(*kc), GFP_KERNEL);
913 if (!kc)
914 return ERR_PTR(-ENOMEM);
915
916 spin_lock_init(&kc->job_lock);
917 INIT_LIST_HEAD(&kc->callback_jobs);
918 INIT_LIST_HEAD(&kc->complete_jobs);
919 INIT_LIST_HEAD(&kc->io_jobs);
920 INIT_LIST_HEAD(&kc->pages_jobs);
921 kc->throttle = throttle;
922
923 r = mempool_init_slab_pool(&kc->job_pool, MIN_JOBS, _job_cache);
924 if (r)
925 goto bad_slab;
926
927 INIT_WORK(&kc->kcopyd_work, do_work);
928 kc->kcopyd_wq = alloc_workqueue("kcopyd", WQ_MEM_RECLAIM, 0);
929 if (!kc->kcopyd_wq) {
930 r = -ENOMEM;
931 goto bad_workqueue;
932 }
933
934 kc->sub_job_size = dm_get_kcopyd_subjob_size();
935 reserve_pages = DIV_ROUND_UP(kc->sub_job_size << SECTOR_SHIFT, PAGE_SIZE);
936
937 kc->pages = NULL;
938 kc->nr_reserved_pages = kc->nr_free_pages = 0;
939 r = client_reserve_pages(kc, reserve_pages);
940 if (r)
941 goto bad_client_pages;
942
943 kc->io_client = dm_io_client_create();
944 if (IS_ERR(kc->io_client)) {
945 r = PTR_ERR(kc->io_client);
946 goto bad_io_client;
947 }
948
949 init_waitqueue_head(&kc->destroyq);
950 atomic_set(&kc->nr_jobs, 0);
951
952 return kc;
953
954bad_io_client:
955 client_free_pages(kc);
956bad_client_pages:
957 destroy_workqueue(kc->kcopyd_wq);
958bad_workqueue:
959 mempool_exit(&kc->job_pool);
960bad_slab:
961 kfree(kc);
962
963 return ERR_PTR(r);
964}
965EXPORT_SYMBOL(dm_kcopyd_client_create);
966
967void dm_kcopyd_client_destroy(struct dm_kcopyd_client *kc)
968{
969 /* Wait for completion of all jobs submitted by this client. */
970 wait_event(kc->destroyq, !atomic_read(&kc->nr_jobs));
971
972 BUG_ON(!list_empty(&kc->callback_jobs));
973 BUG_ON(!list_empty(&kc->complete_jobs));
974 BUG_ON(!list_empty(&kc->io_jobs));
975 BUG_ON(!list_empty(&kc->pages_jobs));
976 destroy_workqueue(kc->kcopyd_wq);
977 dm_io_client_destroy(kc->io_client);
978 client_free_pages(kc);
979 mempool_exit(&kc->job_pool);
980 kfree(kc);
981}
982EXPORT_SYMBOL(dm_kcopyd_client_destroy);
983
984void dm_kcopyd_client_flush(struct dm_kcopyd_client *kc)
985{
986 flush_workqueue(kc->kcopyd_wq);
987}
988EXPORT_SYMBOL(dm_kcopyd_client_flush);
1/*
2 * Copyright (C) 2002 Sistina Software (UK) Limited.
3 * Copyright (C) 2006 Red Hat GmbH
4 *
5 * This file is released under the GPL.
6 *
7 * Kcopyd provides a simple interface for copying an area of one
8 * block-device to one or more other block-devices, with an asynchronous
9 * completion notification.
10 */
11
12#include <linux/types.h>
13#include <linux/atomic.h>
14#include <linux/blkdev.h>
15#include <linux/fs.h>
16#include <linux/init.h>
17#include <linux/list.h>
18#include <linux/mempool.h>
19#include <linux/module.h>
20#include <linux/pagemap.h>
21#include <linux/slab.h>
22#include <linux/vmalloc.h>
23#include <linux/workqueue.h>
24#include <linux/mutex.h>
25#include <linux/delay.h>
26#include <linux/device-mapper.h>
27#include <linux/dm-kcopyd.h>
28
29#include "dm-core.h"
30
31#define SPLIT_COUNT 8
32#define MIN_JOBS 8
33
34#define DEFAULT_SUB_JOB_SIZE_KB 512
35#define MAX_SUB_JOB_SIZE_KB 1024
36
37static unsigned kcopyd_subjob_size_kb = DEFAULT_SUB_JOB_SIZE_KB;
38
39module_param(kcopyd_subjob_size_kb, uint, S_IRUGO | S_IWUSR);
40MODULE_PARM_DESC(kcopyd_subjob_size_kb, "Sub-job size for dm-kcopyd clients");
41
42static unsigned dm_get_kcopyd_subjob_size(void)
43{
44 unsigned sub_job_size_kb;
45
46 sub_job_size_kb = __dm_get_module_param(&kcopyd_subjob_size_kb,
47 DEFAULT_SUB_JOB_SIZE_KB,
48 MAX_SUB_JOB_SIZE_KB);
49
50 return sub_job_size_kb << 1;
51}
52
53/*-----------------------------------------------------------------
54 * Each kcopyd client has its own little pool of preallocated
55 * pages for kcopyd io.
56 *---------------------------------------------------------------*/
57struct dm_kcopyd_client {
58 struct page_list *pages;
59 unsigned nr_reserved_pages;
60 unsigned nr_free_pages;
61 unsigned sub_job_size;
62
63 struct dm_io_client *io_client;
64
65 wait_queue_head_t destroyq;
66
67 mempool_t job_pool;
68
69 struct workqueue_struct *kcopyd_wq;
70 struct work_struct kcopyd_work;
71
72 struct dm_kcopyd_throttle *throttle;
73
74 atomic_t nr_jobs;
75
76/*
77 * We maintain four lists of jobs:
78 *
79 * i) jobs waiting for pages
80 * ii) jobs that have pages, and are waiting for the io to be issued.
81 * iii) jobs that don't need to do any IO and just run a callback
82 * iv) jobs that have completed.
83 *
84 * All four of these are protected by job_lock.
85 */
86 spinlock_t job_lock;
87 struct list_head callback_jobs;
88 struct list_head complete_jobs;
89 struct list_head io_jobs;
90 struct list_head pages_jobs;
91};
92
93static struct page_list zero_page_list;
94
95static DEFINE_SPINLOCK(throttle_spinlock);
96
97/*
98 * IO/IDLE accounting slowly decays after (1 << ACCOUNT_INTERVAL_SHIFT) period.
99 * When total_period >= (1 << ACCOUNT_INTERVAL_SHIFT) the counters are divided
100 * by 2.
101 */
102#define ACCOUNT_INTERVAL_SHIFT SHIFT_HZ
103
104/*
105 * Sleep this number of milliseconds.
106 *
107 * The value was decided experimentally.
108 * Smaller values seem to cause an increased copy rate above the limit.
109 * The reason for this is unknown but possibly due to jiffies rounding errors
110 * or read/write cache inside the disk.
111 */
112#define SLEEP_MSEC 100
113
114/*
115 * Maximum number of sleep events. There is a theoretical livelock if more
116 * kcopyd clients do work simultaneously which this limit avoids.
117 */
118#define MAX_SLEEPS 10
119
120static void io_job_start(struct dm_kcopyd_throttle *t)
121{
122 unsigned throttle, now, difference;
123 int slept = 0, skew;
124
125 if (unlikely(!t))
126 return;
127
128try_again:
129 spin_lock_irq(&throttle_spinlock);
130
131 throttle = READ_ONCE(t->throttle);
132
133 if (likely(throttle >= 100))
134 goto skip_limit;
135
136 now = jiffies;
137 difference = now - t->last_jiffies;
138 t->last_jiffies = now;
139 if (t->num_io_jobs)
140 t->io_period += difference;
141 t->total_period += difference;
142
143 /*
144 * Maintain sane values if we got a temporary overflow.
145 */
146 if (unlikely(t->io_period > t->total_period))
147 t->io_period = t->total_period;
148
149 if (unlikely(t->total_period >= (1 << ACCOUNT_INTERVAL_SHIFT))) {
150 int shift = fls(t->total_period >> ACCOUNT_INTERVAL_SHIFT);
151 t->total_period >>= shift;
152 t->io_period >>= shift;
153 }
154
155 skew = t->io_period - throttle * t->total_period / 100;
156
157 if (unlikely(skew > 0) && slept < MAX_SLEEPS) {
158 slept++;
159 spin_unlock_irq(&throttle_spinlock);
160 msleep(SLEEP_MSEC);
161 goto try_again;
162 }
163
164skip_limit:
165 t->num_io_jobs++;
166
167 spin_unlock_irq(&throttle_spinlock);
168}
169
170static void io_job_finish(struct dm_kcopyd_throttle *t)
171{
172 unsigned long flags;
173
174 if (unlikely(!t))
175 return;
176
177 spin_lock_irqsave(&throttle_spinlock, flags);
178
179 t->num_io_jobs--;
180
181 if (likely(READ_ONCE(t->throttle) >= 100))
182 goto skip_limit;
183
184 if (!t->num_io_jobs) {
185 unsigned now, difference;
186
187 now = jiffies;
188 difference = now - t->last_jiffies;
189 t->last_jiffies = now;
190
191 t->io_period += difference;
192 t->total_period += difference;
193
194 /*
195 * Maintain sane values if we got a temporary overflow.
196 */
197 if (unlikely(t->io_period > t->total_period))
198 t->io_period = t->total_period;
199 }
200
201skip_limit:
202 spin_unlock_irqrestore(&throttle_spinlock, flags);
203}
204
205
206static void wake(struct dm_kcopyd_client *kc)
207{
208 queue_work(kc->kcopyd_wq, &kc->kcopyd_work);
209}
210
211/*
212 * Obtain one page for the use of kcopyd.
213 */
214static struct page_list *alloc_pl(gfp_t gfp)
215{
216 struct page_list *pl;
217
218 pl = kmalloc(sizeof(*pl), gfp);
219 if (!pl)
220 return NULL;
221
222 pl->page = alloc_page(gfp);
223 if (!pl->page) {
224 kfree(pl);
225 return NULL;
226 }
227
228 return pl;
229}
230
231static void free_pl(struct page_list *pl)
232{
233 __free_page(pl->page);
234 kfree(pl);
235}
236
237/*
238 * Add the provided pages to a client's free page list, releasing
239 * back to the system any beyond the reserved_pages limit.
240 */
241static void kcopyd_put_pages(struct dm_kcopyd_client *kc, struct page_list *pl)
242{
243 struct page_list *next;
244
245 do {
246 next = pl->next;
247
248 if (kc->nr_free_pages >= kc->nr_reserved_pages)
249 free_pl(pl);
250 else {
251 pl->next = kc->pages;
252 kc->pages = pl;
253 kc->nr_free_pages++;
254 }
255
256 pl = next;
257 } while (pl);
258}
259
260static int kcopyd_get_pages(struct dm_kcopyd_client *kc,
261 unsigned int nr, struct page_list **pages)
262{
263 struct page_list *pl;
264
265 *pages = NULL;
266
267 do {
268 pl = alloc_pl(__GFP_NOWARN | __GFP_NORETRY | __GFP_KSWAPD_RECLAIM);
269 if (unlikely(!pl)) {
270 /* Use reserved pages */
271 pl = kc->pages;
272 if (unlikely(!pl))
273 goto out_of_memory;
274 kc->pages = pl->next;
275 kc->nr_free_pages--;
276 }
277 pl->next = *pages;
278 *pages = pl;
279 } while (--nr);
280
281 return 0;
282
283out_of_memory:
284 if (*pages)
285 kcopyd_put_pages(kc, *pages);
286 return -ENOMEM;
287}
288
289/*
290 * These three functions resize the page pool.
291 */
292static void drop_pages(struct page_list *pl)
293{
294 struct page_list *next;
295
296 while (pl) {
297 next = pl->next;
298 free_pl(pl);
299 pl = next;
300 }
301}
302
303/*
304 * Allocate and reserve nr_pages for the use of a specific client.
305 */
306static int client_reserve_pages(struct dm_kcopyd_client *kc, unsigned nr_pages)
307{
308 unsigned i;
309 struct page_list *pl = NULL, *next;
310
311 for (i = 0; i < nr_pages; i++) {
312 next = alloc_pl(GFP_KERNEL);
313 if (!next) {
314 if (pl)
315 drop_pages(pl);
316 return -ENOMEM;
317 }
318 next->next = pl;
319 pl = next;
320 }
321
322 kc->nr_reserved_pages += nr_pages;
323 kcopyd_put_pages(kc, pl);
324
325 return 0;
326}
327
328static void client_free_pages(struct dm_kcopyd_client *kc)
329{
330 BUG_ON(kc->nr_free_pages != kc->nr_reserved_pages);
331 drop_pages(kc->pages);
332 kc->pages = NULL;
333 kc->nr_free_pages = kc->nr_reserved_pages = 0;
334}
335
336/*-----------------------------------------------------------------
337 * kcopyd_jobs need to be allocated by the *clients* of kcopyd,
338 * for this reason we use a mempool to prevent the client from
339 * ever having to do io (which could cause a deadlock).
340 *---------------------------------------------------------------*/
341struct kcopyd_job {
342 struct dm_kcopyd_client *kc;
343 struct list_head list;
344 unsigned long flags;
345
346 /*
347 * Error state of the job.
348 */
349 int read_err;
350 unsigned long write_err;
351
352 /*
353 * Either READ or WRITE
354 */
355 int rw;
356 struct dm_io_region source;
357
358 /*
359 * The destinations for the transfer.
360 */
361 unsigned int num_dests;
362 struct dm_io_region dests[DM_KCOPYD_MAX_REGIONS];
363
364 struct page_list *pages;
365
366 /*
367 * Set this to ensure you are notified when the job has
368 * completed. 'context' is for callback to use.
369 */
370 dm_kcopyd_notify_fn fn;
371 void *context;
372
373 /*
374 * These fields are only used if the job has been split
375 * into more manageable parts.
376 */
377 struct mutex lock;
378 atomic_t sub_jobs;
379 sector_t progress;
380 sector_t write_offset;
381
382 struct kcopyd_job *master_job;
383};
384
385static struct kmem_cache *_job_cache;
386
387int __init dm_kcopyd_init(void)
388{
389 _job_cache = kmem_cache_create("kcopyd_job",
390 sizeof(struct kcopyd_job) * (SPLIT_COUNT + 1),
391 __alignof__(struct kcopyd_job), 0, NULL);
392 if (!_job_cache)
393 return -ENOMEM;
394
395 zero_page_list.next = &zero_page_list;
396 zero_page_list.page = ZERO_PAGE(0);
397
398 return 0;
399}
400
401void dm_kcopyd_exit(void)
402{
403 kmem_cache_destroy(_job_cache);
404 _job_cache = NULL;
405}
406
407/*
408 * Functions to push and pop a job onto the head of a given job
409 * list.
410 */
411static struct kcopyd_job *pop_io_job(struct list_head *jobs,
412 struct dm_kcopyd_client *kc)
413{
414 struct kcopyd_job *job;
415
416 /*
417 * For I/O jobs, pop any read, any write without sequential write
418 * constraint and sequential writes that are at the right position.
419 */
420 list_for_each_entry(job, jobs, list) {
421 if (job->rw == READ || !test_bit(DM_KCOPYD_WRITE_SEQ, &job->flags)) {
422 list_del(&job->list);
423 return job;
424 }
425
426 if (job->write_offset == job->master_job->write_offset) {
427 job->master_job->write_offset += job->source.count;
428 list_del(&job->list);
429 return job;
430 }
431 }
432
433 return NULL;
434}
435
436static struct kcopyd_job *pop(struct list_head *jobs,
437 struct dm_kcopyd_client *kc)
438{
439 struct kcopyd_job *job = NULL;
440 unsigned long flags;
441
442 spin_lock_irqsave(&kc->job_lock, flags);
443
444 if (!list_empty(jobs)) {
445 if (jobs == &kc->io_jobs)
446 job = pop_io_job(jobs, kc);
447 else {
448 job = list_entry(jobs->next, struct kcopyd_job, list);
449 list_del(&job->list);
450 }
451 }
452 spin_unlock_irqrestore(&kc->job_lock, flags);
453
454 return job;
455}
456
457static void push(struct list_head *jobs, struct kcopyd_job *job)
458{
459 unsigned long flags;
460 struct dm_kcopyd_client *kc = job->kc;
461
462 spin_lock_irqsave(&kc->job_lock, flags);
463 list_add_tail(&job->list, jobs);
464 spin_unlock_irqrestore(&kc->job_lock, flags);
465}
466
467
468static void push_head(struct list_head *jobs, struct kcopyd_job *job)
469{
470 unsigned long flags;
471 struct dm_kcopyd_client *kc = job->kc;
472
473 spin_lock_irqsave(&kc->job_lock, flags);
474 list_add(&job->list, jobs);
475 spin_unlock_irqrestore(&kc->job_lock, flags);
476}
477
478/*
479 * These three functions process 1 item from the corresponding
480 * job list.
481 *
482 * They return:
483 * < 0: error
484 * 0: success
485 * > 0: can't process yet.
486 */
487static int run_complete_job(struct kcopyd_job *job)
488{
489 void *context = job->context;
490 int read_err = job->read_err;
491 unsigned long write_err = job->write_err;
492 dm_kcopyd_notify_fn fn = job->fn;
493 struct dm_kcopyd_client *kc = job->kc;
494
495 if (job->pages && job->pages != &zero_page_list)
496 kcopyd_put_pages(kc, job->pages);
497 /*
498 * If this is the master job, the sub jobs have already
499 * completed so we can free everything.
500 */
501 if (job->master_job == job) {
502 mutex_destroy(&job->lock);
503 mempool_free(job, &kc->job_pool);
504 }
505 fn(read_err, write_err, context);
506
507 if (atomic_dec_and_test(&kc->nr_jobs))
508 wake_up(&kc->destroyq);
509
510 cond_resched();
511
512 return 0;
513}
514
515static void complete_io(unsigned long error, void *context)
516{
517 struct kcopyd_job *job = (struct kcopyd_job *) context;
518 struct dm_kcopyd_client *kc = job->kc;
519
520 io_job_finish(kc->throttle);
521
522 if (error) {
523 if (op_is_write(job->rw))
524 job->write_err |= error;
525 else
526 job->read_err = 1;
527
528 if (!test_bit(DM_KCOPYD_IGNORE_ERROR, &job->flags)) {
529 push(&kc->complete_jobs, job);
530 wake(kc);
531 return;
532 }
533 }
534
535 if (op_is_write(job->rw))
536 push(&kc->complete_jobs, job);
537
538 else {
539 job->rw = WRITE;
540 push(&kc->io_jobs, job);
541 }
542
543 wake(kc);
544}
545
546/*
547 * Request io on as many buffer heads as we can currently get for
548 * a particular job.
549 */
550static int run_io_job(struct kcopyd_job *job)
551{
552 int r;
553 struct dm_io_request io_req = {
554 .bi_op = job->rw,
555 .bi_op_flags = 0,
556 .mem.type = DM_IO_PAGE_LIST,
557 .mem.ptr.pl = job->pages,
558 .mem.offset = 0,
559 .notify.fn = complete_io,
560 .notify.context = job,
561 .client = job->kc->io_client,
562 };
563
564 /*
565 * If we need to write sequentially and some reads or writes failed,
566 * no point in continuing.
567 */
568 if (test_bit(DM_KCOPYD_WRITE_SEQ, &job->flags) &&
569 job->master_job->write_err) {
570 job->write_err = job->master_job->write_err;
571 return -EIO;
572 }
573
574 io_job_start(job->kc->throttle);
575
576 if (job->rw == READ)
577 r = dm_io(&io_req, 1, &job->source, NULL);
578 else
579 r = dm_io(&io_req, job->num_dests, job->dests, NULL);
580
581 return r;
582}
583
584static int run_pages_job(struct kcopyd_job *job)
585{
586 int r;
587 unsigned nr_pages = dm_div_up(job->dests[0].count, PAGE_SIZE >> 9);
588
589 r = kcopyd_get_pages(job->kc, nr_pages, &job->pages);
590 if (!r) {
591 /* this job is ready for io */
592 push(&job->kc->io_jobs, job);
593 return 0;
594 }
595
596 if (r == -ENOMEM)
597 /* can't complete now */
598 return 1;
599
600 return r;
601}
602
603/*
604 * Run through a list for as long as possible. Returns the count
605 * of successful jobs.
606 */
607static int process_jobs(struct list_head *jobs, struct dm_kcopyd_client *kc,
608 int (*fn) (struct kcopyd_job *))
609{
610 struct kcopyd_job *job;
611 int r, count = 0;
612
613 while ((job = pop(jobs, kc))) {
614
615 r = fn(job);
616
617 if (r < 0) {
618 /* error this rogue job */
619 if (op_is_write(job->rw))
620 job->write_err = (unsigned long) -1L;
621 else
622 job->read_err = 1;
623 push(&kc->complete_jobs, job);
624 wake(kc);
625 break;
626 }
627
628 if (r > 0) {
629 /*
630 * We couldn't service this job ATM, so
631 * push this job back onto the list.
632 */
633 push_head(jobs, job);
634 break;
635 }
636
637 count++;
638 }
639
640 return count;
641}
642
643/*
644 * kcopyd does this every time it's woken up.
645 */
646static void do_work(struct work_struct *work)
647{
648 struct dm_kcopyd_client *kc = container_of(work,
649 struct dm_kcopyd_client, kcopyd_work);
650 struct blk_plug plug;
651 unsigned long flags;
652
653 /*
654 * The order that these are called is *very* important.
655 * complete jobs can free some pages for pages jobs.
656 * Pages jobs when successful will jump onto the io jobs
657 * list. io jobs call wake when they complete and it all
658 * starts again.
659 */
660 spin_lock_irqsave(&kc->job_lock, flags);
661 list_splice_tail_init(&kc->callback_jobs, &kc->complete_jobs);
662 spin_unlock_irqrestore(&kc->job_lock, flags);
663
664 blk_start_plug(&plug);
665 process_jobs(&kc->complete_jobs, kc, run_complete_job);
666 process_jobs(&kc->pages_jobs, kc, run_pages_job);
667 process_jobs(&kc->io_jobs, kc, run_io_job);
668 blk_finish_plug(&plug);
669}
670
671/*
672 * If we are copying a small region we just dispatch a single job
673 * to do the copy, otherwise the io has to be split up into many
674 * jobs.
675 */
676static void dispatch_job(struct kcopyd_job *job)
677{
678 struct dm_kcopyd_client *kc = job->kc;
679 atomic_inc(&kc->nr_jobs);
680 if (unlikely(!job->source.count))
681 push(&kc->callback_jobs, job);
682 else if (job->pages == &zero_page_list)
683 push(&kc->io_jobs, job);
684 else
685 push(&kc->pages_jobs, job);
686 wake(kc);
687}
688
689static void segment_complete(int read_err, unsigned long write_err,
690 void *context)
691{
692 /* FIXME: tidy this function */
693 sector_t progress = 0;
694 sector_t count = 0;
695 struct kcopyd_job *sub_job = (struct kcopyd_job *) context;
696 struct kcopyd_job *job = sub_job->master_job;
697 struct dm_kcopyd_client *kc = job->kc;
698
699 mutex_lock(&job->lock);
700
701 /* update the error */
702 if (read_err)
703 job->read_err = 1;
704
705 if (write_err)
706 job->write_err |= write_err;
707
708 /*
709 * Only dispatch more work if there hasn't been an error.
710 */
711 if ((!job->read_err && !job->write_err) ||
712 test_bit(DM_KCOPYD_IGNORE_ERROR, &job->flags)) {
713 /* get the next chunk of work */
714 progress = job->progress;
715 count = job->source.count - progress;
716 if (count) {
717 if (count > kc->sub_job_size)
718 count = kc->sub_job_size;
719
720 job->progress += count;
721 }
722 }
723 mutex_unlock(&job->lock);
724
725 if (count) {
726 int i;
727
728 *sub_job = *job;
729 sub_job->write_offset = progress;
730 sub_job->source.sector += progress;
731 sub_job->source.count = count;
732
733 for (i = 0; i < job->num_dests; i++) {
734 sub_job->dests[i].sector += progress;
735 sub_job->dests[i].count = count;
736 }
737
738 sub_job->fn = segment_complete;
739 sub_job->context = sub_job;
740 dispatch_job(sub_job);
741
742 } else if (atomic_dec_and_test(&job->sub_jobs)) {
743
744 /*
745 * Queue the completion callback to the kcopyd thread.
746 *
747 * Some callers assume that all the completions are called
748 * from a single thread and don't race with each other.
749 *
750 * We must not call the callback directly here because this
751 * code may not be executing in the thread.
752 */
753 push(&kc->complete_jobs, job);
754 wake(kc);
755 }
756}
757
758/*
759 * Create some sub jobs to share the work between them.
760 */
761static void split_job(struct kcopyd_job *master_job)
762{
763 int i;
764
765 atomic_inc(&master_job->kc->nr_jobs);
766
767 atomic_set(&master_job->sub_jobs, SPLIT_COUNT);
768 for (i = 0; i < SPLIT_COUNT; i++) {
769 master_job[i + 1].master_job = master_job;
770 segment_complete(0, 0u, &master_job[i + 1]);
771 }
772}
773
774void dm_kcopyd_copy(struct dm_kcopyd_client *kc, struct dm_io_region *from,
775 unsigned int num_dests, struct dm_io_region *dests,
776 unsigned int flags, dm_kcopyd_notify_fn fn, void *context)
777{
778 struct kcopyd_job *job;
779 int i;
780
781 /*
782 * Allocate an array of jobs consisting of one master job
783 * followed by SPLIT_COUNT sub jobs.
784 */
785 job = mempool_alloc(&kc->job_pool, GFP_NOIO);
786 mutex_init(&job->lock);
787
788 /*
789 * set up for the read.
790 */
791 job->kc = kc;
792 job->flags = flags;
793 job->read_err = 0;
794 job->write_err = 0;
795
796 job->num_dests = num_dests;
797 memcpy(&job->dests, dests, sizeof(*dests) * num_dests);
798
799 /*
800 * If one of the destination is a host-managed zoned block device,
801 * we need to write sequentially. If one of the destination is a
802 * host-aware device, then leave it to the caller to choose what to do.
803 */
804 if (!test_bit(DM_KCOPYD_WRITE_SEQ, &job->flags)) {
805 for (i = 0; i < job->num_dests; i++) {
806 if (bdev_zoned_model(dests[i].bdev) == BLK_ZONED_HM) {
807 set_bit(DM_KCOPYD_WRITE_SEQ, &job->flags);
808 break;
809 }
810 }
811 }
812
813 /*
814 * If we need to write sequentially, errors cannot be ignored.
815 */
816 if (test_bit(DM_KCOPYD_WRITE_SEQ, &job->flags) &&
817 test_bit(DM_KCOPYD_IGNORE_ERROR, &job->flags))
818 clear_bit(DM_KCOPYD_IGNORE_ERROR, &job->flags);
819
820 if (from) {
821 job->source = *from;
822 job->pages = NULL;
823 job->rw = READ;
824 } else {
825 memset(&job->source, 0, sizeof job->source);
826 job->source.count = job->dests[0].count;
827 job->pages = &zero_page_list;
828
829 /*
830 * Use WRITE ZEROES to optimize zeroing if all dests support it.
831 */
832 job->rw = REQ_OP_WRITE_ZEROES;
833 for (i = 0; i < job->num_dests; i++)
834 if (!bdev_write_zeroes_sectors(job->dests[i].bdev)) {
835 job->rw = WRITE;
836 break;
837 }
838 }
839
840 job->fn = fn;
841 job->context = context;
842 job->master_job = job;
843 job->write_offset = 0;
844
845 if (job->source.count <= kc->sub_job_size)
846 dispatch_job(job);
847 else {
848 job->progress = 0;
849 split_job(job);
850 }
851}
852EXPORT_SYMBOL(dm_kcopyd_copy);
853
854void dm_kcopyd_zero(struct dm_kcopyd_client *kc,
855 unsigned num_dests, struct dm_io_region *dests,
856 unsigned flags, dm_kcopyd_notify_fn fn, void *context)
857{
858 dm_kcopyd_copy(kc, NULL, num_dests, dests, flags, fn, context);
859}
860EXPORT_SYMBOL(dm_kcopyd_zero);
861
862void *dm_kcopyd_prepare_callback(struct dm_kcopyd_client *kc,
863 dm_kcopyd_notify_fn fn, void *context)
864{
865 struct kcopyd_job *job;
866
867 job = mempool_alloc(&kc->job_pool, GFP_NOIO);
868
869 memset(job, 0, sizeof(struct kcopyd_job));
870 job->kc = kc;
871 job->fn = fn;
872 job->context = context;
873 job->master_job = job;
874
875 atomic_inc(&kc->nr_jobs);
876
877 return job;
878}
879EXPORT_SYMBOL(dm_kcopyd_prepare_callback);
880
881void dm_kcopyd_do_callback(void *j, int read_err, unsigned long write_err)
882{
883 struct kcopyd_job *job = j;
884 struct dm_kcopyd_client *kc = job->kc;
885
886 job->read_err = read_err;
887 job->write_err = write_err;
888
889 push(&kc->callback_jobs, job);
890 wake(kc);
891}
892EXPORT_SYMBOL(dm_kcopyd_do_callback);
893
894/*
895 * Cancels a kcopyd job, eg. someone might be deactivating a
896 * mirror.
897 */
898#if 0
899int kcopyd_cancel(struct kcopyd_job *job, int block)
900{
901 /* FIXME: finish */
902 return -1;
903}
904#endif /* 0 */
905
906/*-----------------------------------------------------------------
907 * Client setup
908 *---------------------------------------------------------------*/
909struct dm_kcopyd_client *dm_kcopyd_client_create(struct dm_kcopyd_throttle *throttle)
910{
911 int r;
912 unsigned reserve_pages;
913 struct dm_kcopyd_client *kc;
914
915 kc = kzalloc(sizeof(*kc), GFP_KERNEL);
916 if (!kc)
917 return ERR_PTR(-ENOMEM);
918
919 spin_lock_init(&kc->job_lock);
920 INIT_LIST_HEAD(&kc->callback_jobs);
921 INIT_LIST_HEAD(&kc->complete_jobs);
922 INIT_LIST_HEAD(&kc->io_jobs);
923 INIT_LIST_HEAD(&kc->pages_jobs);
924 kc->throttle = throttle;
925
926 r = mempool_init_slab_pool(&kc->job_pool, MIN_JOBS, _job_cache);
927 if (r)
928 goto bad_slab;
929
930 INIT_WORK(&kc->kcopyd_work, do_work);
931 kc->kcopyd_wq = alloc_workqueue("kcopyd", WQ_MEM_RECLAIM, 0);
932 if (!kc->kcopyd_wq) {
933 r = -ENOMEM;
934 goto bad_workqueue;
935 }
936
937 kc->sub_job_size = dm_get_kcopyd_subjob_size();
938 reserve_pages = DIV_ROUND_UP(kc->sub_job_size << SECTOR_SHIFT, PAGE_SIZE);
939
940 kc->pages = NULL;
941 kc->nr_reserved_pages = kc->nr_free_pages = 0;
942 r = client_reserve_pages(kc, reserve_pages);
943 if (r)
944 goto bad_client_pages;
945
946 kc->io_client = dm_io_client_create();
947 if (IS_ERR(kc->io_client)) {
948 r = PTR_ERR(kc->io_client);
949 goto bad_io_client;
950 }
951
952 init_waitqueue_head(&kc->destroyq);
953 atomic_set(&kc->nr_jobs, 0);
954
955 return kc;
956
957bad_io_client:
958 client_free_pages(kc);
959bad_client_pages:
960 destroy_workqueue(kc->kcopyd_wq);
961bad_workqueue:
962 mempool_exit(&kc->job_pool);
963bad_slab:
964 kfree(kc);
965
966 return ERR_PTR(r);
967}
968EXPORT_SYMBOL(dm_kcopyd_client_create);
969
970void dm_kcopyd_client_destroy(struct dm_kcopyd_client *kc)
971{
972 /* Wait for completion of all jobs submitted by this client. */
973 wait_event(kc->destroyq, !atomic_read(&kc->nr_jobs));
974
975 BUG_ON(!list_empty(&kc->callback_jobs));
976 BUG_ON(!list_empty(&kc->complete_jobs));
977 BUG_ON(!list_empty(&kc->io_jobs));
978 BUG_ON(!list_empty(&kc->pages_jobs));
979 destroy_workqueue(kc->kcopyd_wq);
980 dm_io_client_destroy(kc->io_client);
981 client_free_pages(kc);
982 mempool_exit(&kc->job_pool);
983 kfree(kc);
984}
985EXPORT_SYMBOL(dm_kcopyd_client_destroy);