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);