xref: /linux/drivers/md/dm-log.c (revision c537b994505099b7197e7d3125b942ecbcc51eb6) 
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 #define DM_MSG_PREFIX "mirror log"
16 
17 static LIST_HEAD(_log_types);
18 static DEFINE_SPINLOCK(_lock);
19 
20 int dm_register_dirty_log_type(struct dirty_log_type *type)
21 {
22 	spin_lock(&_lock);
23 	type->use_count = 0;
24 	list_add(&type->list, &_log_types);
25 	spin_unlock(&_lock);
26 
27 	return 0;
28 }
29 
30 int dm_unregister_dirty_log_type(struct dirty_log_type *type)
31 {
32 	spin_lock(&_lock);
33 
34 	if (type->use_count)
35 		DMWARN("Attempt to unregister a log type that is still in use");
36 	else
37 		list_del(&type->list);
38 
39 	spin_unlock(&_lock);
40 
41 	return 0;
42 }
43 
44 static struct dirty_log_type *get_type(const char *type_name)
45 {
46 	struct dirty_log_type *type;
47 
48 	spin_lock(&_lock);
49 	list_for_each_entry (type, &_log_types, list)
50 		if (!strcmp(type_name, type->name)) {
51 			if (!type->use_count && !try_module_get(type->module)){
52 				spin_unlock(&_lock);
53 				return NULL;
54 			}
55 			type->use_count++;
56 			spin_unlock(&_lock);
57 			return type;
58 		}
59 
60 	spin_unlock(&_lock);
61 	return NULL;
62 }
63 
64 static void put_type(struct dirty_log_type *type)
65 {
66 	spin_lock(&_lock);
67 	if (!--type->use_count)
68 		module_put(type->module);
69 	spin_unlock(&_lock);
70 }
71 
72 struct dirty_log *dm_create_dirty_log(const char *type_name, struct dm_target *ti,
73 				      unsigned int argc, char **argv)
74 {
75 	struct dirty_log_type *type;
76 	struct dirty_log *log;
77 
78 	log = kmalloc(sizeof(*log), GFP_KERNEL);
79 	if (!log)
80 		return NULL;
81 
82 	type = get_type(type_name);
83 	if (!type) {
84 		kfree(log);
85 		return NULL;
86 	}
87 
88 	log->type = type;
89 	if (type->ctr(log, ti, argc, argv)) {
90 		kfree(log);
91 		put_type(type);
92 		return NULL;
93 	}
94 
95 	return log;
96 }
97 
98 void dm_destroy_dirty_log(struct dirty_log *log)
99 {
100 	log->type->dtr(log);
101 	put_type(log->type);
102 	kfree(log);
103 }
104 
105 /*-----------------------------------------------------------------
106  * Persistent and core logs share a lot of their implementation.
107  * FIXME: need a reload method to be called from a resume
108  *---------------------------------------------------------------*/
109 /*
110  * Magic for persistent mirrors: "MiRr"
111  */
112 #define MIRROR_MAGIC 0x4D695272
113 
114 /*
115  * The on-disk version of the metadata.
116  */
117 #define MIRROR_DISK_VERSION 2
118 #define LOG_OFFSET 2
119 
120 struct log_header {
121 	uint32_t magic;
122 
123 	/*
124 	 * Simple, incrementing version. no backward
125 	 * compatibility.
126 	 */
127 	uint32_t version;
128 	sector_t nr_regions;
129 };
130 
131 struct log_c {
132 	struct dm_target *ti;
133 	int touched;
134 	uint32_t region_size;
135 	unsigned int region_count;
136 	region_t sync_count;
137 
138 	unsigned bitset_uint32_count;
139 	uint32_t *clean_bits;
140 	uint32_t *sync_bits;
141 	uint32_t *recovering_bits;	/* FIXME: this seems excessive */
142 
143 	int sync_search;
144 
145 	/* Resync flag */
146 	enum sync {
147 		DEFAULTSYNC,	/* Synchronize if necessary */
148 		NOSYNC,		/* Devices known to be already in sync */
149 		FORCESYNC,	/* Force a sync to happen */
150 	} sync;
151 
152 	/*
153 	 * Disk log fields
154 	 */
155 	struct dm_dev *log_dev;
156 	struct log_header header;
157 
158 	struct io_region header_location;
159 	struct log_header *disk_header;
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  * core log constructor/destructor
245  *
246  * argv contains region_size followed optionally by [no]sync
247  *--------------------------------------------------------------*/
248 #define BYTE_SHIFT 3
249 static int create_log_context(struct dirty_log *log, struct dm_target *ti,
250 			      unsigned int argc, char **argv,
251 			      struct dm_dev *dev)
252 {
253 	enum sync sync = DEFAULTSYNC;
254 
255 	struct log_c *lc;
256 	uint32_t region_size;
257 	unsigned int region_count;
258 	size_t bitset_size, buf_size;
259 
260 	if (argc < 1 || argc > 2) {
261 		DMWARN("wrong number of arguments to mirror log");
262 		return -EINVAL;
263 	}
264 
265 	if (argc > 1) {
266 		if (!strcmp(argv[1], "sync"))
267 			sync = FORCESYNC;
268 		else if (!strcmp(argv[1], "nosync"))
269 			sync = NOSYNC;
270 		else {
271 			DMWARN("unrecognised sync argument to mirror log: %s",
272 			       argv[1]);
273 			return -EINVAL;
274 		}
275 	}
276 
277 	if (sscanf(argv[0], "%u", &region_size) != 1) {
278 		DMWARN("invalid region size string");
279 		return -EINVAL;
280 	}
281 
282 	region_count = dm_sector_div_up(ti->len, region_size);
283 
284 	lc = kmalloc(sizeof(*lc), GFP_KERNEL);
285 	if (!lc) {
286 		DMWARN("couldn't allocate core log");
287 		return -ENOMEM;
288 	}
289 
290 	lc->ti = ti;
291 	lc->touched = 0;
292 	lc->region_size = region_size;
293 	lc->region_count = region_count;
294 	lc->sync = sync;
295 
296 	/*
297 	 * Work out how many "unsigned long"s we need to hold the bitset.
298 	 */
299 	bitset_size = dm_round_up(region_count,
300 				  sizeof(*lc->clean_bits) << BYTE_SHIFT);
301 	bitset_size >>= BYTE_SHIFT;
302 
303 	lc->bitset_uint32_count = bitset_size / sizeof(*lc->clean_bits);
304 
305 	/*
306 	 * Disk log?
307 	 */
308 	if (!dev) {
309 		lc->clean_bits = vmalloc(bitset_size);
310 		if (!lc->clean_bits) {
311 			DMWARN("couldn't allocate clean bitset");
312 			kfree(lc);
313 			return -ENOMEM;
314 		}
315 		lc->disk_header = NULL;
316 	} else {
317 		lc->log_dev = dev;
318 		lc->header_location.bdev = lc->log_dev->bdev;
319 		lc->header_location.sector = 0;
320 
321 		/*
322 		 * Buffer holds both header and bitset.
323 		 */
324 		buf_size = dm_round_up((LOG_OFFSET << SECTOR_SHIFT) +
325 				       bitset_size, ti->limits.hardsect_size);
326 		lc->header_location.count = buf_size >> SECTOR_SHIFT;
327 
328 		lc->disk_header = vmalloc(buf_size);
329 		if (!lc->disk_header) {
330 			DMWARN("couldn't allocate disk log buffer");
331 			kfree(lc);
332 			return -ENOMEM;
333 		}
334 
335 		lc->clean_bits = (void *)lc->disk_header +
336 				 (LOG_OFFSET << SECTOR_SHIFT);
337 	}
338 
339 	memset(lc->clean_bits, -1, bitset_size);
340 
341 	lc->sync_bits = vmalloc(bitset_size);
342 	if (!lc->sync_bits) {
343 		DMWARN("couldn't allocate sync bitset");
344 		if (!dev)
345 			vfree(lc->clean_bits);
346 		vfree(lc->disk_header);
347 		kfree(lc);
348 		return -ENOMEM;
349 	}
350 	memset(lc->sync_bits, (sync == NOSYNC) ? -1 : 0, bitset_size);
351 	lc->sync_count = (sync == NOSYNC) ? region_count : 0;
352 
353 	lc->recovering_bits = vmalloc(bitset_size);
354 	if (!lc->recovering_bits) {
355 		DMWARN("couldn't allocate sync bitset");
356 		vfree(lc->sync_bits);
357 		if (!dev)
358 			vfree(lc->clean_bits);
359 		vfree(lc->disk_header);
360 		kfree(lc);
361 		return -ENOMEM;
362 	}
363 	memset(lc->recovering_bits, 0, bitset_size);
364 	lc->sync_search = 0;
365 	log->context = lc;
366 
367 	return 0;
368 }
369 
370 static int core_ctr(struct dirty_log *log, struct dm_target *ti,
371 		    unsigned int argc, char **argv)
372 {
373 	return create_log_context(log, ti, argc, argv, NULL);
374 }
375 
376 static void destroy_log_context(struct log_c *lc)
377 {
378 	vfree(lc->sync_bits);
379 	vfree(lc->recovering_bits);
380 	kfree(lc);
381 }
382 
383 static void core_dtr(struct dirty_log *log)
384 {
385 	struct log_c *lc = (struct log_c *) log->context;
386 
387 	vfree(lc->clean_bits);
388 	destroy_log_context(lc);
389 }
390 
391 /*----------------------------------------------------------------
392  * disk log constructor/destructor
393  *
394  * argv contains log_device region_size followed optionally by [no]sync
395  *--------------------------------------------------------------*/
396 static int disk_ctr(struct dirty_log *log, struct dm_target *ti,
397 		    unsigned int argc, char **argv)
398 {
399 	int r;
400 	struct dm_dev *dev;
401 
402 	if (argc < 2 || argc > 3) {
403 		DMWARN("wrong number of arguments to disk mirror log");
404 		return -EINVAL;
405 	}
406 
407 	r = dm_get_device(ti, argv[0], 0, 0 /* FIXME */,
408 			  FMODE_READ | FMODE_WRITE, &dev);
409 	if (r)
410 		return r;
411 
412 	r = create_log_context(log, ti, argc - 1, argv + 1, dev);
413 	if (r) {
414 		dm_put_device(ti, dev);
415 		return r;
416 	}
417 
418 	return 0;
419 }
420 
421 static void disk_dtr(struct dirty_log *log)
422 {
423 	struct log_c *lc = (struct log_c *) log->context;
424 
425 	dm_put_device(lc->ti, lc->log_dev);
426 	vfree(lc->disk_header);
427 	destroy_log_context(lc);
428 }
429 
430 static int count_bits32(uint32_t *addr, unsigned size)
431 {
432 	int count = 0, i;
433 
434 	for (i = 0; i < size; i++) {
435 		count += hweight32(*(addr+i));
436 	}
437 	return count;
438 }
439 
440 static int disk_resume(struct dirty_log *log)
441 {
442 	int r;
443 	unsigned i;
444 	struct log_c *lc = (struct log_c *) log->context;
445 	size_t size = lc->bitset_uint32_count * sizeof(uint32_t);
446 
447 	/* read the disk header */
448 	r = read_header(lc);
449 	if (r)
450 		return r;
451 
452 	/* set or clear any new bits -- device has grown */
453 	if (lc->sync == NOSYNC)
454 		for (i = lc->header.nr_regions; i < lc->region_count; i++)
455 			/* FIXME: amazingly inefficient */
456 			log_set_bit(lc, lc->clean_bits, i);
457 	else
458 		for (i = lc->header.nr_regions; i < lc->region_count; i++)
459 			/* FIXME: amazingly inefficient */
460 			log_clear_bit(lc, lc->clean_bits, i);
461 
462 	/* clear any old bits -- device has shrunk */
463 	for (i = lc->region_count; i % (sizeof(*lc->clean_bits) << BYTE_SHIFT); i++)
464 		log_clear_bit(lc, lc->clean_bits, i);
465 
466 	/* copy clean across to sync */
467 	memcpy(lc->sync_bits, lc->clean_bits, size);
468 	lc->sync_count = count_bits32(lc->clean_bits, lc->bitset_uint32_count);
469 	lc->sync_search = 0;
470 
471 	/* set the correct number of regions in the header */
472 	lc->header.nr_regions = lc->region_count;
473 
474 	/* write the new header */
475 	return write_header(lc);
476 }
477 
478 static uint32_t core_get_region_size(struct dirty_log *log)
479 {
480 	struct log_c *lc = (struct log_c *) log->context;
481 	return lc->region_size;
482 }
483 
484 static int core_resume(struct dirty_log *log)
485 {
486 	struct log_c *lc = (struct log_c *) log->context;
487 	lc->sync_search = 0;
488 	return 0;
489 }
490 
491 static int core_is_clean(struct dirty_log *log, region_t region)
492 {
493 	struct log_c *lc = (struct log_c *) log->context;
494 	return log_test_bit(lc->clean_bits, region);
495 }
496 
497 static int core_in_sync(struct dirty_log *log, region_t region, int block)
498 {
499 	struct log_c *lc = (struct log_c *) log->context;
500 	return log_test_bit(lc->sync_bits, region);
501 }
502 
503 static int core_flush(struct dirty_log *log)
504 {
505 	/* no op */
506 	return 0;
507 }
508 
509 static int disk_flush(struct dirty_log *log)
510 {
511 	int r;
512 	struct log_c *lc = (struct log_c *) log->context;
513 
514 	/* only write if the log has changed */
515 	if (!lc->touched)
516 		return 0;
517 
518 	r = write_header(lc);
519 	if (!r)
520 		lc->touched = 0;
521 
522 	return r;
523 }
524 
525 static void core_mark_region(struct dirty_log *log, region_t region)
526 {
527 	struct log_c *lc = (struct log_c *) log->context;
528 	log_clear_bit(lc, lc->clean_bits, region);
529 }
530 
531 static void core_clear_region(struct dirty_log *log, region_t region)
532 {
533 	struct log_c *lc = (struct log_c *) log->context;
534 	log_set_bit(lc, lc->clean_bits, region);
535 }
536 
537 static int core_get_resync_work(struct dirty_log *log, region_t *region)
538 {
539 	struct log_c *lc = (struct log_c *) log->context;
540 
541 	if (lc->sync_search >= lc->region_count)
542 		return 0;
543 
544 	do {
545 		*region = ext2_find_next_zero_bit(
546 					     (unsigned long *) lc->sync_bits,
547 					     lc->region_count,
548 					     lc->sync_search);
549 		lc->sync_search = *region + 1;
550 
551 		if (*region >= lc->region_count)
552 			return 0;
553 
554 	} while (log_test_bit(lc->recovering_bits, *region));
555 
556 	log_set_bit(lc, lc->recovering_bits, *region);
557 	return 1;
558 }
559 
560 static void core_set_region_sync(struct dirty_log *log, region_t region,
561 				 int in_sync)
562 {
563 	struct log_c *lc = (struct log_c *) log->context;
564 
565 	log_clear_bit(lc, lc->recovering_bits, region);
566 	if (in_sync) {
567 		log_set_bit(lc, lc->sync_bits, region);
568                 lc->sync_count++;
569         } else if (log_test_bit(lc->sync_bits, region)) {
570 		lc->sync_count--;
571 		log_clear_bit(lc, lc->sync_bits, region);
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 	.resume = core_resume,
633 	.get_region_size = core_get_region_size,
634 	.is_clean = core_is_clean,
635 	.in_sync = core_in_sync,
636 	.flush = core_flush,
637 	.mark_region = core_mark_region,
638 	.clear_region = core_clear_region,
639 	.get_resync_work = core_get_resync_work,
640 	.set_region_sync = core_set_region_sync,
641 	.get_sync_count = core_get_sync_count,
642 	.status = core_status,
643 };
644 
645 static struct dirty_log_type _disk_type = {
646 	.name = "disk",
647 	.module = THIS_MODULE,
648 	.ctr = disk_ctr,
649 	.dtr = disk_dtr,
650 	.suspend = disk_flush,
651 	.resume = disk_resume,
652 	.get_region_size = core_get_region_size,
653 	.is_clean = core_is_clean,
654 	.in_sync = core_in_sync,
655 	.flush = disk_flush,
656 	.mark_region = core_mark_region,
657 	.clear_region = core_clear_region,
658 	.get_resync_work = core_get_resync_work,
659 	.set_region_sync = core_set_region_sync,
660 	.get_sync_count = core_get_sync_count,
661 	.status = disk_status,
662 };
663 
664 int __init dm_dirty_log_init(void)
665 {
666 	int r;
667 
668 	r = dm_register_dirty_log_type(&_core_type);
669 	if (r)
670 		DMWARN("couldn't register core log");
671 
672 	r = dm_register_dirty_log_type(&_disk_type);
673 	if (r) {
674 		DMWARN("couldn't register disk type");
675 		dm_unregister_dirty_log_type(&_core_type);
676 	}
677 
678 	return r;
679 }
680 
681 void dm_dirty_log_exit(void)
682 {
683 	dm_unregister_dirty_log_type(&_disk_type);
684 	dm_unregister_dirty_log_type(&_core_type);
685 }
686 
687 EXPORT_SYMBOL(dm_register_dirty_log_type);
688 EXPORT_SYMBOL(dm_unregister_dirty_log_type);
689 EXPORT_SYMBOL(dm_create_dirty_log);
690 EXPORT_SYMBOL(dm_destroy_dirty_log);
691