xref: /linux/drivers/md/dm-log.c (revision f3d9478b2ce468c3115b02ecae7e975990697f15) 
1 /*
2  * Copyright (C) 2003 Sistina Software
3  *
4  * This file is released under the LGPL.
5  */
6 
7 #include <linux/init.h>
8 #include <linux/slab.h>
9 #include <linux/module.h>
10 #include <linux/vmalloc.h>
11 
12 #include "dm-log.h"
13 #include "dm-io.h"
14 
15 static LIST_HEAD(_log_types);
16 static DEFINE_SPINLOCK(_lock);
17 
18 int dm_register_dirty_log_type(struct dirty_log_type *type)
19 {
20 	spin_lock(&_lock);
21 	type->use_count = 0;
22 	list_add(&type->list, &_log_types);
23 	spin_unlock(&_lock);
24 
25 	return 0;
26 }
27 
28 int dm_unregister_dirty_log_type(struct dirty_log_type *type)
29 {
30 	spin_lock(&_lock);
31 
32 	if (type->use_count)
33 		DMWARN("Attempt to unregister a log type that is still in use");
34 	else
35 		list_del(&type->list);
36 
37 	spin_unlock(&_lock);
38 
39 	return 0;
40 }
41 
42 static struct dirty_log_type *get_type(const char *type_name)
43 {
44 	struct dirty_log_type *type;
45 
46 	spin_lock(&_lock);
47 	list_for_each_entry (type, &_log_types, list)
48 		if (!strcmp(type_name, type->name)) {
49 			if (!type->use_count && !try_module_get(type->module)){
50 				spin_unlock(&_lock);
51 				return NULL;
52 			}
53 			type->use_count++;
54 			spin_unlock(&_lock);
55 			return type;
56 		}
57 
58 	spin_unlock(&_lock);
59 	return NULL;
60 }
61 
62 static void put_type(struct dirty_log_type *type)
63 {
64 	spin_lock(&_lock);
65 	if (!--type->use_count)
66 		module_put(type->module);
67 	spin_unlock(&_lock);
68 }
69 
70 struct dirty_log *dm_create_dirty_log(const char *type_name, struct dm_target *ti,
71 				      unsigned int argc, char **argv)
72 {
73 	struct dirty_log_type *type;
74 	struct dirty_log *log;
75 
76 	log = kmalloc(sizeof(*log), GFP_KERNEL);
77 	if (!log)
78 		return NULL;
79 
80 	type = get_type(type_name);
81 	if (!type) {
82 		kfree(log);
83 		return NULL;
84 	}
85 
86 	log->type = type;
87 	if (type->ctr(log, ti, argc, argv)) {
88 		kfree(log);
89 		put_type(type);
90 		return NULL;
91 	}
92 
93 	return log;
94 }
95 
96 void dm_destroy_dirty_log(struct dirty_log *log)
97 {
98 	log->type->dtr(log);
99 	put_type(log->type);
100 	kfree(log);
101 }
102 
103 /*-----------------------------------------------------------------
104  * Persistent and core logs share a lot of their implementation.
105  * FIXME: need a reload method to be called from a resume
106  *---------------------------------------------------------------*/
107 /*
108  * Magic for persistent mirrors: "MiRr"
109  */
110 #define MIRROR_MAGIC 0x4D695272
111 
112 /*
113  * The on-disk version of the metadata.
114  */
115 #define MIRROR_DISK_VERSION 2
116 #define LOG_OFFSET 2
117 
118 struct log_header {
119 	uint32_t magic;
120 
121 	/*
122 	 * Simple, incrementing version. no backward
123 	 * compatibility.
124 	 */
125 	uint32_t version;
126 	sector_t nr_regions;
127 };
128 
129 struct log_c {
130 	struct dm_target *ti;
131 	int touched;
132 	uint32_t region_size;
133 	unsigned int region_count;
134 	region_t sync_count;
135 
136 	unsigned bitset_uint32_count;
137 	uint32_t *clean_bits;
138 	uint32_t *sync_bits;
139 	uint32_t *recovering_bits;	/* FIXME: this seems excessive */
140 
141 	int sync_search;
142 
143 	/* Resync flag */
144 	enum sync {
145 		DEFAULTSYNC,	/* Synchronize if necessary */
146 		NOSYNC,		/* Devices known to be already in sync */
147 		FORCESYNC,	/* Force a sync to happen */
148 	} sync;
149 
150 	/*
151 	 * Disk log fields
152 	 */
153 	struct dm_dev *log_dev;
154 	struct log_header header;
155 
156 	struct io_region header_location;
157 	struct log_header *disk_header;
158 
159 	struct io_region bits_location;
160 };
161 
162 /*
163  * The touched member needs to be updated every time we access
164  * one of the bitsets.
165  */
166 static  inline int log_test_bit(uint32_t *bs, unsigned bit)
167 {
168 	return ext2_test_bit(bit, (unsigned long *) bs) ? 1 : 0;
169 }
170 
171 static inline void log_set_bit(struct log_c *l,
172 			       uint32_t *bs, unsigned bit)
173 {
174 	ext2_set_bit(bit, (unsigned long *) bs);
175 	l->touched = 1;
176 }
177 
178 static inline void log_clear_bit(struct log_c *l,
179 				 uint32_t *bs, unsigned bit)
180 {
181 	ext2_clear_bit(bit, (unsigned long *) bs);
182 	l->touched = 1;
183 }
184 
185 /*----------------------------------------------------------------
186  * Header IO
187  *--------------------------------------------------------------*/
188 static void header_to_disk(struct log_header *core, struct log_header *disk)
189 {
190 	disk->magic = cpu_to_le32(core->magic);
191 	disk->version = cpu_to_le32(core->version);
192 	disk->nr_regions = cpu_to_le64(core->nr_regions);
193 }
194 
195 static void header_from_disk(struct log_header *core, struct log_header *disk)
196 {
197 	core->magic = le32_to_cpu(disk->magic);
198 	core->version = le32_to_cpu(disk->version);
199 	core->nr_regions = le64_to_cpu(disk->nr_regions);
200 }
201 
202 static int read_header(struct log_c *log)
203 {
204 	int r;
205 	unsigned long ebits;
206 
207 	r = dm_io_sync_vm(1, &log->header_location, READ,
208 			  log->disk_header, &ebits);
209 	if (r)
210 		return r;
211 
212 	header_from_disk(&log->header, log->disk_header);
213 
214 	/* New log required? */
215 	if (log->sync != DEFAULTSYNC || log->header.magic != MIRROR_MAGIC) {
216 		log->header.magic = MIRROR_MAGIC;
217 		log->header.version = MIRROR_DISK_VERSION;
218 		log->header.nr_regions = 0;
219 	}
220 
221 #ifdef __LITTLE_ENDIAN
222 	if (log->header.version == 1)
223 		log->header.version = 2;
224 #endif
225 
226 	if (log->header.version != MIRROR_DISK_VERSION) {
227 		DMWARN("incompatible disk log version");
228 		return -EINVAL;
229 	}
230 
231 	return 0;
232 }
233 
234 static inline int write_header(struct log_c *log)
235 {
236 	unsigned long ebits;
237 
238 	header_to_disk(&log->header, log->disk_header);
239 	return dm_io_sync_vm(1, &log->header_location, WRITE,
240 			     log->disk_header, &ebits);
241 }
242 
243 /*----------------------------------------------------------------
244  * Bits IO
245  *--------------------------------------------------------------*/
246 static int read_bits(struct log_c *log)
247 {
248 	int r;
249 	unsigned long ebits;
250 
251 	r = dm_io_sync_vm(1, &log->bits_location, READ,
252 			  log->clean_bits, &ebits);
253 	if (r)
254 		return r;
255 
256 	return 0;
257 }
258 
259 static int write_bits(struct log_c *log)
260 {
261 	unsigned long ebits;
262 	return dm_io_sync_vm(1, &log->bits_location, WRITE,
263 			     log->clean_bits, &ebits);
264 }
265 
266 /*----------------------------------------------------------------
267  * core log constructor/destructor
268  *
269  * argv contains region_size followed optionally by [no]sync
270  *--------------------------------------------------------------*/
271 #define BYTE_SHIFT 3
272 static int core_ctr(struct dirty_log *log, struct dm_target *ti,
273 		    unsigned int argc, char **argv)
274 {
275 	enum sync sync = DEFAULTSYNC;
276 
277 	struct log_c *lc;
278 	uint32_t region_size;
279 	unsigned int region_count;
280 	size_t bitset_size;
281 
282 	if (argc < 1 || argc > 2) {
283 		DMWARN("wrong number of arguments to mirror log");
284 		return -EINVAL;
285 	}
286 
287 	if (argc > 1) {
288 		if (!strcmp(argv[1], "sync"))
289 			sync = FORCESYNC;
290 		else if (!strcmp(argv[1], "nosync"))
291 			sync = NOSYNC;
292 		else {
293 			DMWARN("unrecognised sync argument to mirror log: %s",
294 			       argv[1]);
295 			return -EINVAL;
296 		}
297 	}
298 
299 	if (sscanf(argv[0], "%u", &region_size) != 1) {
300 		DMWARN("invalid region size string");
301 		return -EINVAL;
302 	}
303 
304 	region_count = dm_sector_div_up(ti->len, region_size);
305 
306 	lc = kmalloc(sizeof(*lc), GFP_KERNEL);
307 	if (!lc) {
308 		DMWARN("couldn't allocate core log");
309 		return -ENOMEM;
310 	}
311 
312 	lc->ti = ti;
313 	lc->touched = 0;
314 	lc->region_size = region_size;
315 	lc->region_count = region_count;
316 	lc->sync = sync;
317 
318 	/*
319 	 * Work out how many "unsigned long"s we need to hold the bitset.
320 	 */
321 	bitset_size = dm_round_up(region_count,
322 				  sizeof(unsigned long) << BYTE_SHIFT);
323 	bitset_size >>= BYTE_SHIFT;
324 
325 	lc->bitset_uint32_count = bitset_size / 4;
326 	lc->clean_bits = vmalloc(bitset_size);
327 	if (!lc->clean_bits) {
328 		DMWARN("couldn't allocate clean bitset");
329 		kfree(lc);
330 		return -ENOMEM;
331 	}
332 	memset(lc->clean_bits, -1, bitset_size);
333 
334 	lc->sync_bits = vmalloc(bitset_size);
335 	if (!lc->sync_bits) {
336 		DMWARN("couldn't allocate sync bitset");
337 		vfree(lc->clean_bits);
338 		kfree(lc);
339 		return -ENOMEM;
340 	}
341 	memset(lc->sync_bits, (sync == NOSYNC) ? -1 : 0, bitset_size);
342 	lc->sync_count = (sync == NOSYNC) ? region_count : 0;
343 
344 	lc->recovering_bits = vmalloc(bitset_size);
345 	if (!lc->recovering_bits) {
346 		DMWARN("couldn't allocate sync bitset");
347 		vfree(lc->sync_bits);
348 		vfree(lc->clean_bits);
349 		kfree(lc);
350 		return -ENOMEM;
351 	}
352 	memset(lc->recovering_bits, 0, bitset_size);
353 	lc->sync_search = 0;
354 	log->context = lc;
355 	return 0;
356 }
357 
358 static void core_dtr(struct dirty_log *log)
359 {
360 	struct log_c *lc = (struct log_c *) log->context;
361 	vfree(lc->clean_bits);
362 	vfree(lc->sync_bits);
363 	vfree(lc->recovering_bits);
364 	kfree(lc);
365 }
366 
367 /*----------------------------------------------------------------
368  * disk log constructor/destructor
369  *
370  * argv contains log_device region_size followed optionally by [no]sync
371  *--------------------------------------------------------------*/
372 static int disk_ctr(struct dirty_log *log, struct dm_target *ti,
373 		    unsigned int argc, char **argv)
374 {
375 	int r;
376 	size_t size;
377 	struct log_c *lc;
378 	struct dm_dev *dev;
379 
380 	if (argc < 2 || argc > 3) {
381 		DMWARN("wrong number of arguments to disk mirror log");
382 		return -EINVAL;
383 	}
384 
385 	r = dm_get_device(ti, argv[0], 0, 0 /* FIXME */,
386 			  FMODE_READ | FMODE_WRITE, &dev);
387 	if (r)
388 		return r;
389 
390 	r = core_ctr(log, ti, argc - 1, argv + 1);
391 	if (r) {
392 		dm_put_device(ti, dev);
393 		return r;
394 	}
395 
396 	lc = (struct log_c *) log->context;
397 	lc->log_dev = dev;
398 
399 	/* setup the disk header fields */
400 	lc->header_location.bdev = lc->log_dev->bdev;
401 	lc->header_location.sector = 0;
402 	lc->header_location.count = 1;
403 
404 	/*
405 	 * We can't read less than this amount, even though we'll
406 	 * not be using most of this space.
407 	 */
408 	lc->disk_header = vmalloc(1 << SECTOR_SHIFT);
409 	if (!lc->disk_header)
410 		goto bad;
411 
412 	/* setup the disk bitset fields */
413 	lc->bits_location.bdev = lc->log_dev->bdev;
414 	lc->bits_location.sector = LOG_OFFSET;
415 
416 	size = dm_round_up(lc->bitset_uint32_count * sizeof(uint32_t),
417 			   1 << SECTOR_SHIFT);
418 	lc->bits_location.count = size >> SECTOR_SHIFT;
419 	return 0;
420 
421  bad:
422 	dm_put_device(ti, lc->log_dev);
423 	core_dtr(log);
424 	return -ENOMEM;
425 }
426 
427 static void disk_dtr(struct dirty_log *log)
428 {
429 	struct log_c *lc = (struct log_c *) log->context;
430 	dm_put_device(lc->ti, lc->log_dev);
431 	vfree(lc->disk_header);
432 	core_dtr(log);
433 }
434 
435 static int count_bits32(uint32_t *addr, unsigned size)
436 {
437 	int count = 0, i;
438 
439 	for (i = 0; i < size; i++) {
440 		count += hweight32(*(addr+i));
441 	}
442 	return count;
443 }
444 
445 static int disk_resume(struct dirty_log *log)
446 {
447 	int r;
448 	unsigned i;
449 	struct log_c *lc = (struct log_c *) log->context;
450 	size_t size = lc->bitset_uint32_count * sizeof(uint32_t);
451 
452 	/* read the disk header */
453 	r = read_header(lc);
454 	if (r)
455 		return r;
456 
457 	/* read the bits */
458 	r = read_bits(lc);
459 	if (r)
460 		return r;
461 
462 	/* set or clear any new bits */
463 	if (lc->sync == NOSYNC)
464 		for (i = lc->header.nr_regions; i < lc->region_count; i++)
465 			/* FIXME: amazingly inefficient */
466 			log_set_bit(lc, lc->clean_bits, i);
467 	else
468 		for (i = lc->header.nr_regions; i < lc->region_count; i++)
469 			/* FIXME: amazingly inefficient */
470 			log_clear_bit(lc, lc->clean_bits, i);
471 
472 	/* copy clean across to sync */
473 	memcpy(lc->sync_bits, lc->clean_bits, size);
474 	lc->sync_count = count_bits32(lc->clean_bits, lc->bitset_uint32_count);
475 
476 	/* write the bits */
477 	r = write_bits(lc);
478 	if (r)
479 		return r;
480 
481 	/* set the correct number of regions in the header */
482 	lc->header.nr_regions = lc->region_count;
483 
484 	/* write the new header */
485 	return write_header(lc);
486 }
487 
488 static uint32_t core_get_region_size(struct dirty_log *log)
489 {
490 	struct log_c *lc = (struct log_c *) log->context;
491 	return lc->region_size;
492 }
493 
494 static int core_is_clean(struct dirty_log *log, region_t region)
495 {
496 	struct log_c *lc = (struct log_c *) log->context;
497 	return log_test_bit(lc->clean_bits, region);
498 }
499 
500 static int core_in_sync(struct dirty_log *log, region_t region, int block)
501 {
502 	struct log_c *lc = (struct log_c *) log->context;
503 	return log_test_bit(lc->sync_bits, region);
504 }
505 
506 static int core_flush(struct dirty_log *log)
507 {
508 	/* no op */
509 	return 0;
510 }
511 
512 static int disk_flush(struct dirty_log *log)
513 {
514 	int r;
515 	struct log_c *lc = (struct log_c *) log->context;
516 
517 	/* only write if the log has changed */
518 	if (!lc->touched)
519 		return 0;
520 
521 	r = write_bits(lc);
522 	if (!r)
523 		lc->touched = 0;
524 
525 	return r;
526 }
527 
528 static void core_mark_region(struct dirty_log *log, region_t region)
529 {
530 	struct log_c *lc = (struct log_c *) log->context;
531 	log_clear_bit(lc, lc->clean_bits, region);
532 }
533 
534 static void core_clear_region(struct dirty_log *log, region_t region)
535 {
536 	struct log_c *lc = (struct log_c *) log->context;
537 	log_set_bit(lc, lc->clean_bits, region);
538 }
539 
540 static int core_get_resync_work(struct dirty_log *log, region_t *region)
541 {
542 	struct log_c *lc = (struct log_c *) log->context;
543 
544 	if (lc->sync_search >= lc->region_count)
545 		return 0;
546 
547 	do {
548 		*region = ext2_find_next_zero_bit(
549 					     (unsigned long *) lc->sync_bits,
550 					     lc->region_count,
551 					     lc->sync_search);
552 		lc->sync_search = *region + 1;
553 
554 		if (*region >= lc->region_count)
555 			return 0;
556 
557 	} while (log_test_bit(lc->recovering_bits, *region));
558 
559 	log_set_bit(lc, lc->recovering_bits, *region);
560 	return 1;
561 }
562 
563 static void core_complete_resync_work(struct dirty_log *log, region_t region,
564 				      int success)
565 {
566 	struct log_c *lc = (struct log_c *) log->context;
567 
568 	log_clear_bit(lc, lc->recovering_bits, region);
569 	if (success) {
570 		log_set_bit(lc, lc->sync_bits, region);
571                 lc->sync_count++;
572         }
573 }
574 
575 static region_t core_get_sync_count(struct dirty_log *log)
576 {
577         struct log_c *lc = (struct log_c *) log->context;
578 
579         return lc->sync_count;
580 }
581 
582 #define	DMEMIT_SYNC \
583 	if (lc->sync != DEFAULTSYNC) \
584 		DMEMIT("%ssync ", lc->sync == NOSYNC ? "no" : "")
585 
586 static int core_status(struct dirty_log *log, status_type_t status,
587 		       char *result, unsigned int maxlen)
588 {
589 	int sz = 0;
590 	struct log_c *lc = log->context;
591 
592 	switch(status) {
593 	case STATUSTYPE_INFO:
594 		break;
595 
596 	case STATUSTYPE_TABLE:
597 		DMEMIT("%s %u %u ", log->type->name,
598 		       lc->sync == DEFAULTSYNC ? 1 : 2, lc->region_size);
599 		DMEMIT_SYNC;
600 	}
601 
602 	return sz;
603 }
604 
605 static int disk_status(struct dirty_log *log, status_type_t status,
606 		       char *result, unsigned int maxlen)
607 {
608 	int sz = 0;
609 	char buffer[16];
610 	struct log_c *lc = log->context;
611 
612 	switch(status) {
613 	case STATUSTYPE_INFO:
614 		break;
615 
616 	case STATUSTYPE_TABLE:
617 		format_dev_t(buffer, lc->log_dev->bdev->bd_dev);
618 		DMEMIT("%s %u %s %u ", log->type->name,
619 		       lc->sync == DEFAULTSYNC ? 2 : 3, buffer,
620 		       lc->region_size);
621 		DMEMIT_SYNC;
622 	}
623 
624 	return sz;
625 }
626 
627 static struct dirty_log_type _core_type = {
628 	.name = "core",
629 	.module = THIS_MODULE,
630 	.ctr = core_ctr,
631 	.dtr = core_dtr,
632 	.get_region_size = core_get_region_size,
633 	.is_clean = core_is_clean,
634 	.in_sync = core_in_sync,
635 	.flush = core_flush,
636 	.mark_region = core_mark_region,
637 	.clear_region = core_clear_region,
638 	.get_resync_work = core_get_resync_work,
639 	.complete_resync_work = core_complete_resync_work,
640 	.get_sync_count = core_get_sync_count,
641 	.status = core_status,
642 };
643 
644 static struct dirty_log_type _disk_type = {
645 	.name = "disk",
646 	.module = THIS_MODULE,
647 	.ctr = disk_ctr,
648 	.dtr = disk_dtr,
649 	.suspend = disk_flush,
650 	.resume = disk_resume,
651 	.get_region_size = core_get_region_size,
652 	.is_clean = core_is_clean,
653 	.in_sync = core_in_sync,
654 	.flush = disk_flush,
655 	.mark_region = core_mark_region,
656 	.clear_region = core_clear_region,
657 	.get_resync_work = core_get_resync_work,
658 	.complete_resync_work = core_complete_resync_work,
659 	.get_sync_count = core_get_sync_count,
660 	.status = disk_status,
661 };
662 
663 int __init dm_dirty_log_init(void)
664 {
665 	int r;
666 
667 	r = dm_register_dirty_log_type(&_core_type);
668 	if (r)
669 		DMWARN("couldn't register core log");
670 
671 	r = dm_register_dirty_log_type(&_disk_type);
672 	if (r) {
673 		DMWARN("couldn't register disk type");
674 		dm_unregister_dirty_log_type(&_core_type);
675 	}
676 
677 	return r;
678 }
679 
680 void dm_dirty_log_exit(void)
681 {
682 	dm_unregister_dirty_log_type(&_disk_type);
683 	dm_unregister_dirty_log_type(&_core_type);
684 }
685 
686 EXPORT_SYMBOL(dm_register_dirty_log_type);
687 EXPORT_SYMBOL(dm_unregister_dirty_log_type);
688 EXPORT_SYMBOL(dm_create_dirty_log);
689 EXPORT_SYMBOL(dm_destroy_dirty_log);
690