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