blob: b46f6c575f7ebd5ee79dbe543525ed5459e173d6 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Copyright (C) 2002 Sistina Software (UK) Limited.
3 *
4 * This file is released under the GPL.
5 *
6 * Kcopyd provides a simple interface for copying an area of one
7 * block-device to one or more other block-devices, with an asynchronous
8 * completion notification.
9 */
10
Alan Cox715b49e2006-01-18 17:44:07 -080011#include <asm/types.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070012#include <asm/atomic.h>
13
14#include <linux/blkdev.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070015#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>
Arjan van de Ven48c9c272006-03-27 01:18:20 -080024#include <linux/mutex.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070025
26#include "kcopyd.h"
27
28static struct workqueue_struct *_kcopyd_wq;
29static struct work_struct _kcopyd_work;
30
31static inline void wake(void)
32{
33 queue_work(_kcopyd_wq, &_kcopyd_work);
34}
35
36/*-----------------------------------------------------------------
37 * Each kcopyd client has its own little pool of preallocated
38 * pages for kcopyd io.
39 *---------------------------------------------------------------*/
40struct kcopyd_client {
41 struct list_head list;
42
43 spinlock_t lock;
44 struct page_list *pages;
45 unsigned int nr_pages;
46 unsigned int nr_free_pages;
Alasdair G Kergon138728dc2006-03-27 01:17:50 -080047
48 wait_queue_head_t destroyq;
49 atomic_t nr_jobs;
Linus Torvalds1da177e2005-04-16 15:20:36 -070050};
51
52static struct page_list *alloc_pl(void)
53{
54 struct page_list *pl;
55
56 pl = kmalloc(sizeof(*pl), GFP_KERNEL);
57 if (!pl)
58 return NULL;
59
60 pl->page = alloc_page(GFP_KERNEL);
61 if (!pl->page) {
62 kfree(pl);
63 return NULL;
64 }
65
66 return pl;
67}
68
69static void free_pl(struct page_list *pl)
70{
71 __free_page(pl->page);
72 kfree(pl);
73}
74
75static int kcopyd_get_pages(struct kcopyd_client *kc,
76 unsigned int nr, struct page_list **pages)
77{
78 struct page_list *pl;
79
80 spin_lock(&kc->lock);
81 if (kc->nr_free_pages < nr) {
82 spin_unlock(&kc->lock);
83 return -ENOMEM;
84 }
85
86 kc->nr_free_pages -= nr;
87 for (*pages = pl = kc->pages; --nr; pl = pl->next)
88 ;
89
90 kc->pages = pl->next;
91 pl->next = NULL;
92
93 spin_unlock(&kc->lock);
94
95 return 0;
96}
97
98static void kcopyd_put_pages(struct kcopyd_client *kc, struct page_list *pl)
99{
100 struct page_list *cursor;
101
102 spin_lock(&kc->lock);
103 for (cursor = pl; cursor->next; cursor = cursor->next)
104 kc->nr_free_pages++;
105
106 kc->nr_free_pages++;
107 cursor->next = kc->pages;
108 kc->pages = pl;
109 spin_unlock(&kc->lock);
110}
111
112/*
113 * These three functions resize the page pool.
114 */
115static void drop_pages(struct page_list *pl)
116{
117 struct page_list *next;
118
119 while (pl) {
120 next = pl->next;
121 free_pl(pl);
122 pl = next;
123 }
124}
125
126static int client_alloc_pages(struct kcopyd_client *kc, unsigned int nr)
127{
128 unsigned int i;
129 struct page_list *pl = NULL, *next;
130
131 for (i = 0; i < nr; i++) {
132 next = alloc_pl();
133 if (!next) {
134 if (pl)
135 drop_pages(pl);
136 return -ENOMEM;
137 }
138 next->next = pl;
139 pl = next;
140 }
141
142 kcopyd_put_pages(kc, pl);
143 kc->nr_pages += nr;
144 return 0;
145}
146
147static void client_free_pages(struct kcopyd_client *kc)
148{
149 BUG_ON(kc->nr_free_pages != kc->nr_pages);
150 drop_pages(kc->pages);
151 kc->pages = NULL;
152 kc->nr_free_pages = kc->nr_pages = 0;
153}
154
155/*-----------------------------------------------------------------
156 * kcopyd_jobs need to be allocated by the *clients* of kcopyd,
157 * for this reason we use a mempool to prevent the client from
158 * ever having to do io (which could cause a deadlock).
159 *---------------------------------------------------------------*/
160struct kcopyd_job {
161 struct kcopyd_client *kc;
162 struct list_head list;
163 unsigned long flags;
164
165 /*
166 * Error state of the job.
167 */
168 int read_err;
169 unsigned int write_err;
170
171 /*
172 * Either READ or WRITE
173 */
174 int rw;
175 struct io_region source;
176
177 /*
178 * The destinations for the transfer.
179 */
180 unsigned int num_dests;
181 struct io_region dests[KCOPYD_MAX_REGIONS];
182
183 sector_t offset;
184 unsigned int nr_pages;
185 struct page_list *pages;
186
187 /*
188 * Set this to ensure you are notified when the job has
189 * completed. 'context' is for callback to use.
190 */
191 kcopyd_notify_fn fn;
192 void *context;
193
194 /*
195 * These fields are only used if the job has been split
196 * into more manageable parts.
197 */
198 struct semaphore lock;
199 atomic_t sub_jobs;
200 sector_t progress;
201};
202
203/* FIXME: this should scale with the number of pages */
204#define MIN_JOBS 512
205
Christoph Lametere18b8902006-12-06 20:33:20 -0800206static struct kmem_cache *_job_cache;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207static mempool_t *_job_pool;
208
209/*
210 * We maintain three lists of jobs:
211 *
212 * i) jobs waiting for pages
213 * ii) jobs that have pages, and are waiting for the io to be issued.
214 * iii) jobs that have completed.
215 *
216 * All three of these are protected by job_lock.
217 */
218static DEFINE_SPINLOCK(_job_lock);
219
220static LIST_HEAD(_complete_jobs);
221static LIST_HEAD(_io_jobs);
222static LIST_HEAD(_pages_jobs);
223
224static int jobs_init(void)
225{
226 _job_cache = kmem_cache_create("kcopyd-jobs",
227 sizeof(struct kcopyd_job),
228 __alignof__(struct kcopyd_job),
229 0, NULL, NULL);
230 if (!_job_cache)
231 return -ENOMEM;
232
Matthew Dobson93d23412006-03-26 01:37:50 -0800233 _job_pool = mempool_create_slab_pool(MIN_JOBS, _job_cache);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234 if (!_job_pool) {
235 kmem_cache_destroy(_job_cache);
236 return -ENOMEM;
237 }
238
239 return 0;
240}
241
242static void jobs_exit(void)
243{
244 BUG_ON(!list_empty(&_complete_jobs));
245 BUG_ON(!list_empty(&_io_jobs));
246 BUG_ON(!list_empty(&_pages_jobs));
247
248 mempool_destroy(_job_pool);
249 kmem_cache_destroy(_job_cache);
250 _job_pool = NULL;
251 _job_cache = NULL;
252}
253
254/*
255 * Functions to push and pop a job onto the head of a given job
256 * list.
257 */
258static inline struct kcopyd_job *pop(struct list_head *jobs)
259{
260 struct kcopyd_job *job = NULL;
261 unsigned long flags;
262
263 spin_lock_irqsave(&_job_lock, flags);
264
265 if (!list_empty(jobs)) {
266 job = list_entry(jobs->next, struct kcopyd_job, list);
267 list_del(&job->list);
268 }
269 spin_unlock_irqrestore(&_job_lock, flags);
270
271 return job;
272}
273
274static inline void push(struct list_head *jobs, struct kcopyd_job *job)
275{
276 unsigned long flags;
277
278 spin_lock_irqsave(&_job_lock, flags);
279 list_add_tail(&job->list, jobs);
280 spin_unlock_irqrestore(&_job_lock, flags);
281}
282
283/*
284 * These three functions process 1 item from the corresponding
285 * job list.
286 *
287 * They return:
288 * < 0: error
289 * 0: success
290 * > 0: can't process yet.
291 */
292static int run_complete_job(struct kcopyd_job *job)
293{
294 void *context = job->context;
295 int read_err = job->read_err;
296 unsigned int write_err = job->write_err;
297 kcopyd_notify_fn fn = job->fn;
Alasdair G Kergon138728dc2006-03-27 01:17:50 -0800298 struct kcopyd_client *kc = job->kc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299
Alasdair G Kergon138728dc2006-03-27 01:17:50 -0800300 kcopyd_put_pages(kc, job->pages);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 mempool_free(job, _job_pool);
302 fn(read_err, write_err, context);
Alasdair G Kergon138728dc2006-03-27 01:17:50 -0800303
304 if (atomic_dec_and_test(&kc->nr_jobs))
305 wake_up(&kc->destroyq);
306
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307 return 0;
308}
309
310static void complete_io(unsigned long error, void *context)
311{
312 struct kcopyd_job *job = (struct kcopyd_job *) context;
313
314 if (error) {
315 if (job->rw == WRITE)
Jonathan Brassowce503f52006-06-26 00:27:30 -0700316 job->write_err |= error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317 else
318 job->read_err = 1;
319
320 if (!test_bit(KCOPYD_IGNORE_ERROR, &job->flags)) {
321 push(&_complete_jobs, job);
322 wake();
323 return;
324 }
325 }
326
327 if (job->rw == WRITE)
328 push(&_complete_jobs, job);
329
330 else {
331 job->rw = WRITE;
332 push(&_io_jobs, job);
333 }
334
335 wake();
336}
337
338/*
339 * Request io on as many buffer heads as we can currently get for
340 * a particular job.
341 */
342static int run_io_job(struct kcopyd_job *job)
343{
344 int r;
345
346 if (job->rw == READ)
347 r = dm_io_async(1, &job->source, job->rw,
348 job->pages,
349 job->offset, complete_io, job);
350
351 else
352 r = dm_io_async(job->num_dests, job->dests, job->rw,
353 job->pages,
354 job->offset, complete_io, job);
355
356 return r;
357}
358
359static int run_pages_job(struct kcopyd_job *job)
360{
361 int r;
362
363 job->nr_pages = dm_div_up(job->dests[0].count + job->offset,
364 PAGE_SIZE >> 9);
365 r = kcopyd_get_pages(job->kc, job->nr_pages, &job->pages);
366 if (!r) {
367 /* this job is ready for io */
368 push(&_io_jobs, job);
369 return 0;
370 }
371
372 if (r == -ENOMEM)
373 /* can't complete now */
374 return 1;
375
376 return r;
377}
378
379/*
380 * Run through a list for as long as possible. Returns the count
381 * of successful jobs.
382 */
383static int process_jobs(struct list_head *jobs, int (*fn) (struct kcopyd_job *))
384{
385 struct kcopyd_job *job;
386 int r, count = 0;
387
388 while ((job = pop(jobs))) {
389
390 r = fn(job);
391
392 if (r < 0) {
393 /* error this rogue job */
394 if (job->rw == WRITE)
395 job->write_err = (unsigned int) -1;
396 else
397 job->read_err = 1;
398 push(&_complete_jobs, job);
399 break;
400 }
401
402 if (r > 0) {
403 /*
404 * We couldn't service this job ATM, so
405 * push this job back onto the list.
406 */
407 push(jobs, job);
408 break;
409 }
410
411 count++;
412 }
413
414 return count;
415}
416
417/*
418 * kcopyd does this every time it's woken up.
419 */
David Howellsc4028952006-11-22 14:57:56 +0000420static void do_work(struct work_struct *ignored)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421{
422 /*
423 * The order that these are called is *very* important.
424 * complete jobs can free some pages for pages jobs.
425 * Pages jobs when successful will jump onto the io jobs
426 * list. io jobs call wake when they complete and it all
427 * starts again.
428 */
429 process_jobs(&_complete_jobs, run_complete_job);
430 process_jobs(&_pages_jobs, run_pages_job);
431 process_jobs(&_io_jobs, run_io_job);
432}
433
434/*
435 * If we are copying a small region we just dispatch a single job
436 * to do the copy, otherwise the io has to be split up into many
437 * jobs.
438 */
439static void dispatch_job(struct kcopyd_job *job)
440{
Alasdair G Kergon138728dc2006-03-27 01:17:50 -0800441 atomic_inc(&job->kc->nr_jobs);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700442 push(&_pages_jobs, job);
443 wake();
444}
445
446#define SUB_JOB_SIZE 128
447static void segment_complete(int read_err,
448 unsigned int write_err, void *context)
449{
450 /* FIXME: tidy this function */
451 sector_t progress = 0;
452 sector_t count = 0;
453 struct kcopyd_job *job = (struct kcopyd_job *) context;
454
455 down(&job->lock);
456
457 /* update the error */
458 if (read_err)
459 job->read_err = 1;
460
461 if (write_err)
Jonathan Brassowce503f52006-06-26 00:27:30 -0700462 job->write_err |= write_err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700463
464 /*
465 * Only dispatch more work if there hasn't been an error.
466 */
467 if ((!job->read_err && !job->write_err) ||
468 test_bit(KCOPYD_IGNORE_ERROR, &job->flags)) {
469 /* get the next chunk of work */
470 progress = job->progress;
471 count = job->source.count - progress;
472 if (count) {
473 if (count > SUB_JOB_SIZE)
474 count = SUB_JOB_SIZE;
475
476 job->progress += count;
477 }
478 }
479 up(&job->lock);
480
481 if (count) {
482 int i;
483 struct kcopyd_job *sub_job = mempool_alloc(_job_pool, GFP_NOIO);
484
485 *sub_job = *job;
486 sub_job->source.sector += progress;
487 sub_job->source.count = count;
488
489 for (i = 0; i < job->num_dests; i++) {
490 sub_job->dests[i].sector += progress;
491 sub_job->dests[i].count = count;
492 }
493
494 sub_job->fn = segment_complete;
495 sub_job->context = job;
496 dispatch_job(sub_job);
497
498 } else if (atomic_dec_and_test(&job->sub_jobs)) {
499
500 /*
501 * To avoid a race we must keep the job around
502 * until after the notify function has completed.
503 * Otherwise the client may try and stop the job
504 * after we've completed.
505 */
506 job->fn(read_err, write_err, job->context);
507 mempool_free(job, _job_pool);
508 }
509}
510
511/*
512 * Create some little jobs that will do the move between
513 * them.
514 */
515#define SPLIT_COUNT 8
516static void split_job(struct kcopyd_job *job)
517{
518 int i;
519
520 atomic_set(&job->sub_jobs, SPLIT_COUNT);
521 for (i = 0; i < SPLIT_COUNT; i++)
522 segment_complete(0, 0u, job);
523}
524
525int kcopyd_copy(struct kcopyd_client *kc, struct io_region *from,
526 unsigned int num_dests, struct io_region *dests,
527 unsigned int flags, kcopyd_notify_fn fn, void *context)
528{
529 struct kcopyd_job *job;
530
531 /*
532 * Allocate a new job.
533 */
534 job = mempool_alloc(_job_pool, GFP_NOIO);
535
536 /*
537 * set up for the read.
538 */
539 job->kc = kc;
540 job->flags = flags;
541 job->read_err = 0;
542 job->write_err = 0;
543 job->rw = READ;
544
545 job->source = *from;
546
547 job->num_dests = num_dests;
548 memcpy(&job->dests, dests, sizeof(*dests) * num_dests);
549
550 job->offset = 0;
551 job->nr_pages = 0;
552 job->pages = NULL;
553
554 job->fn = fn;
555 job->context = context;
556
557 if (job->source.count < SUB_JOB_SIZE)
558 dispatch_job(job);
559
560 else {
561 init_MUTEX(&job->lock);
562 job->progress = 0;
563 split_job(job);
564 }
565
566 return 0;
567}
568
569/*
570 * Cancels a kcopyd job, eg. someone might be deactivating a
571 * mirror.
572 */
Adrian Bunk0b563062006-01-06 00:20:08 -0800573#if 0
Linus Torvalds1da177e2005-04-16 15:20:36 -0700574int kcopyd_cancel(struct kcopyd_job *job, int block)
575{
576 /* FIXME: finish */
577 return -1;
578}
Adrian Bunk0b563062006-01-06 00:20:08 -0800579#endif /* 0 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700580
581/*-----------------------------------------------------------------
582 * Unit setup
583 *---------------------------------------------------------------*/
Arjan van de Ven48c9c272006-03-27 01:18:20 -0800584static DEFINE_MUTEX(_client_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700585static LIST_HEAD(_clients);
586
587static void client_add(struct kcopyd_client *kc)
588{
Arjan van de Ven48c9c272006-03-27 01:18:20 -0800589 mutex_lock(&_client_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700590 list_add(&kc->list, &_clients);
Arjan van de Ven48c9c272006-03-27 01:18:20 -0800591 mutex_unlock(&_client_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700592}
593
594static void client_del(struct kcopyd_client *kc)
595{
Arjan van de Ven48c9c272006-03-27 01:18:20 -0800596 mutex_lock(&_client_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700597 list_del(&kc->list);
Arjan van de Ven48c9c272006-03-27 01:18:20 -0800598 mutex_unlock(&_client_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700599}
600
Ingo Molnar14cc3e22006-03-26 01:37:14 -0800601static DEFINE_MUTEX(kcopyd_init_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700602static int kcopyd_clients = 0;
603
604static int kcopyd_init(void)
605{
606 int r;
607
Ingo Molnar14cc3e22006-03-26 01:37:14 -0800608 mutex_lock(&kcopyd_init_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700609
610 if (kcopyd_clients) {
611 /* Already initialized. */
612 kcopyd_clients++;
Ingo Molnar14cc3e22006-03-26 01:37:14 -0800613 mutex_unlock(&kcopyd_init_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700614 return 0;
615 }
616
617 r = jobs_init();
618 if (r) {
Ingo Molnar14cc3e22006-03-26 01:37:14 -0800619 mutex_unlock(&kcopyd_init_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700620 return r;
621 }
622
623 _kcopyd_wq = create_singlethread_workqueue("kcopyd");
624 if (!_kcopyd_wq) {
625 jobs_exit();
Ingo Molnar14cc3e22006-03-26 01:37:14 -0800626 mutex_unlock(&kcopyd_init_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700627 return -ENOMEM;
628 }
629
630 kcopyd_clients++;
David Howellsc4028952006-11-22 14:57:56 +0000631 INIT_WORK(&_kcopyd_work, do_work);
Ingo Molnar14cc3e22006-03-26 01:37:14 -0800632 mutex_unlock(&kcopyd_init_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700633 return 0;
634}
635
636static void kcopyd_exit(void)
637{
Ingo Molnar14cc3e22006-03-26 01:37:14 -0800638 mutex_lock(&kcopyd_init_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700639 kcopyd_clients--;
640 if (!kcopyd_clients) {
641 jobs_exit();
642 destroy_workqueue(_kcopyd_wq);
643 _kcopyd_wq = NULL;
644 }
Ingo Molnar14cc3e22006-03-26 01:37:14 -0800645 mutex_unlock(&kcopyd_init_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700646}
647
648int kcopyd_client_create(unsigned int nr_pages, struct kcopyd_client **result)
649{
650 int r = 0;
651 struct kcopyd_client *kc;
652
653 r = kcopyd_init();
654 if (r)
655 return r;
656
657 kc = kmalloc(sizeof(*kc), GFP_KERNEL);
658 if (!kc) {
659 kcopyd_exit();
660 return -ENOMEM;
661 }
662
663 spin_lock_init(&kc->lock);
664 kc->pages = NULL;
665 kc->nr_pages = kc->nr_free_pages = 0;
666 r = client_alloc_pages(kc, nr_pages);
667 if (r) {
668 kfree(kc);
669 kcopyd_exit();
670 return r;
671 }
672
673 r = dm_io_get(nr_pages);
674 if (r) {
675 client_free_pages(kc);
676 kfree(kc);
677 kcopyd_exit();
678 return r;
679 }
680
Alasdair G Kergon138728dc2006-03-27 01:17:50 -0800681 init_waitqueue_head(&kc->destroyq);
682 atomic_set(&kc->nr_jobs, 0);
683
Linus Torvalds1da177e2005-04-16 15:20:36 -0700684 client_add(kc);
685 *result = kc;
686 return 0;
687}
688
689void kcopyd_client_destroy(struct kcopyd_client *kc)
690{
Alasdair G Kergon138728dc2006-03-27 01:17:50 -0800691 /* Wait for completion of all jobs submitted by this client. */
692 wait_event(kc->destroyq, !atomic_read(&kc->nr_jobs));
693
Linus Torvalds1da177e2005-04-16 15:20:36 -0700694 dm_io_put(kc->nr_pages);
695 client_free_pages(kc);
696 client_del(kc);
697 kfree(kc);
698 kcopyd_exit();
699}
700
701EXPORT_SYMBOL(kcopyd_client_create);
702EXPORT_SYMBOL(kcopyd_client_destroy);
703EXPORT_SYMBOL(kcopyd_copy);