xref: /openbmc/linux/drivers/md/dm-log.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
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 	struct dm_io_request io_req;
153 
154 	/*
155 	 * Disk log fields
156 	 */
157 	int log_dev_failed;
158 	struct dm_dev *log_dev;
159 	struct log_header header;
160 
161 	struct io_region header_location;
162 	struct log_header *disk_header;
163 };
164 
165 /*
166  * The touched member needs to be updated every time we access
167  * one of the bitsets.
168  */
169 static  inline int log_test_bit(uint32_t *bs, unsigned bit)
170 {
171 	return ext2_test_bit(bit, (unsigned long *) bs) ? 1 : 0;
172 }
173 
174 static inline void log_set_bit(struct log_c *l,
175 			       uint32_t *bs, unsigned bit)
176 {
177 	ext2_set_bit(bit, (unsigned long *) bs);
178 	l->touched = 1;
179 }
180 
181 static inline void log_clear_bit(struct log_c *l,
182 				 uint32_t *bs, unsigned bit)
183 {
184 	ext2_clear_bit(bit, (unsigned long *) bs);
185 	l->touched = 1;
186 }
187 
188 /*----------------------------------------------------------------
189  * Header IO
190  *--------------------------------------------------------------*/
191 static void header_to_disk(struct log_header *core, struct log_header *disk)
192 {
193 	disk->magic = cpu_to_le32(core->magic);
194 	disk->version = cpu_to_le32(core->version);
195 	disk->nr_regions = cpu_to_le64(core->nr_regions);
196 }
197 
198 static void header_from_disk(struct log_header *core, struct log_header *disk)
199 {
200 	core->magic = le32_to_cpu(disk->magic);
201 	core->version = le32_to_cpu(disk->version);
202 	core->nr_regions = le64_to_cpu(disk->nr_regions);
203 }
204 
205 static int rw_header(struct log_c *lc, int rw)
206 {
207 	lc->io_req.bi_rw = rw;
208 	lc->io_req.mem.ptr.vma = lc->disk_header;
209 	lc->io_req.notify.fn = NULL;
210 
211 	return dm_io(&lc->io_req, 1, &lc->header_location, NULL);
212 }
213 
214 static int read_header(struct log_c *log)
215 {
216 	int r;
217 
218 	r = rw_header(log, READ);
219 	if (r)
220 		return r;
221 
222 	header_from_disk(&log->header, log->disk_header);
223 
224 	/* New log required? */
225 	if (log->sync != DEFAULTSYNC || log->header.magic != MIRROR_MAGIC) {
226 		log->header.magic = MIRROR_MAGIC;
227 		log->header.version = MIRROR_DISK_VERSION;
228 		log->header.nr_regions = 0;
229 	}
230 
231 #ifdef __LITTLE_ENDIAN
232 	if (log->header.version == 1)
233 		log->header.version = 2;
234 #endif
235 
236 	if (log->header.version != MIRROR_DISK_VERSION) {
237 		DMWARN("incompatible disk log version");
238 		return -EINVAL;
239 	}
240 
241 	return 0;
242 }
243 
244 static inline int write_header(struct log_c *log)
245 {
246 	header_to_disk(&log->header, log->disk_header);
247 	return rw_header(log, WRITE);
248 }
249 
250 /*----------------------------------------------------------------
251  * core log constructor/destructor
252  *
253  * argv contains region_size followed optionally by [no]sync
254  *--------------------------------------------------------------*/
255 #define BYTE_SHIFT 3
256 static int create_log_context(struct dirty_log *log, struct dm_target *ti,
257 			      unsigned int argc, char **argv,
258 			      struct dm_dev *dev)
259 {
260 	enum sync sync = DEFAULTSYNC;
261 
262 	struct log_c *lc;
263 	uint32_t region_size;
264 	unsigned int region_count;
265 	size_t bitset_size, buf_size;
266 	int r;
267 
268 	if (argc < 1 || argc > 2) {
269 		DMWARN("wrong number of arguments to mirror log");
270 		return -EINVAL;
271 	}
272 
273 	if (argc > 1) {
274 		if (!strcmp(argv[1], "sync"))
275 			sync = FORCESYNC;
276 		else if (!strcmp(argv[1], "nosync"))
277 			sync = NOSYNC;
278 		else {
279 			DMWARN("unrecognised sync argument to mirror log: %s",
280 			       argv[1]);
281 			return -EINVAL;
282 		}
283 	}
284 
285 	if (sscanf(argv[0], "%u", &region_size) != 1) {
286 		DMWARN("invalid region size string");
287 		return -EINVAL;
288 	}
289 
290 	region_count = dm_sector_div_up(ti->len, region_size);
291 
292 	lc = kmalloc(sizeof(*lc), GFP_KERNEL);
293 	if (!lc) {
294 		DMWARN("couldn't allocate core log");
295 		return -ENOMEM;
296 	}
297 
298 	lc->ti = ti;
299 	lc->touched = 0;
300 	lc->region_size = region_size;
301 	lc->region_count = region_count;
302 	lc->sync = sync;
303 
304 	/*
305 	 * Work out how many "unsigned long"s we need to hold the bitset.
306 	 */
307 	bitset_size = dm_round_up(region_count,
308 				  sizeof(*lc->clean_bits) << BYTE_SHIFT);
309 	bitset_size >>= BYTE_SHIFT;
310 
311 	lc->bitset_uint32_count = bitset_size / sizeof(*lc->clean_bits);
312 
313 	/*
314 	 * Disk log?
315 	 */
316 	if (!dev) {
317 		lc->clean_bits = vmalloc(bitset_size);
318 		if (!lc->clean_bits) {
319 			DMWARN("couldn't allocate clean bitset");
320 			kfree(lc);
321 			return -ENOMEM;
322 		}
323 		lc->disk_header = NULL;
324 	} else {
325 		lc->log_dev = dev;
326 		lc->log_dev_failed = 0;
327 		lc->header_location.bdev = lc->log_dev->bdev;
328 		lc->header_location.sector = 0;
329 
330 		/*
331 		 * Buffer holds both header and bitset.
332 		 */
333 		buf_size = dm_round_up((LOG_OFFSET << SECTOR_SHIFT) +
334 				       bitset_size, ti->limits.hardsect_size);
335 		lc->header_location.count = buf_size >> SECTOR_SHIFT;
336 		lc->io_req.mem.type = DM_IO_VMA;
337 		lc->io_req.client = dm_io_client_create(dm_div_up(buf_size,
338 								   PAGE_SIZE));
339 		if (IS_ERR(lc->io_req.client)) {
340 			r = PTR_ERR(lc->io_req.client);
341 			DMWARN("couldn't allocate disk io client");
342 			kfree(lc);
343 			return -ENOMEM;
344 		}
345 
346 		lc->disk_header = vmalloc(buf_size);
347 		if (!lc->disk_header) {
348 			DMWARN("couldn't allocate disk log buffer");
349 			kfree(lc);
350 			return -ENOMEM;
351 		}
352 
353 		lc->clean_bits = (void *)lc->disk_header +
354 				 (LOG_OFFSET << SECTOR_SHIFT);
355 	}
356 
357 	memset(lc->clean_bits, -1, bitset_size);
358 
359 	lc->sync_bits = vmalloc(bitset_size);
360 	if (!lc->sync_bits) {
361 		DMWARN("couldn't allocate sync bitset");
362 		if (!dev)
363 			vfree(lc->clean_bits);
364 		vfree(lc->disk_header);
365 		kfree(lc);
366 		return -ENOMEM;
367 	}
368 	memset(lc->sync_bits, (sync == NOSYNC) ? -1 : 0, bitset_size);
369 	lc->sync_count = (sync == NOSYNC) ? region_count : 0;
370 
371 	lc->recovering_bits = vmalloc(bitset_size);
372 	if (!lc->recovering_bits) {
373 		DMWARN("couldn't allocate sync bitset");
374 		vfree(lc->sync_bits);
375 		if (!dev)
376 			vfree(lc->clean_bits);
377 		vfree(lc->disk_header);
378 		kfree(lc);
379 		return -ENOMEM;
380 	}
381 	memset(lc->recovering_bits, 0, bitset_size);
382 	lc->sync_search = 0;
383 	log->context = lc;
384 
385 	return 0;
386 }
387 
388 static int core_ctr(struct dirty_log *log, struct dm_target *ti,
389 		    unsigned int argc, char **argv)
390 {
391 	return create_log_context(log, ti, argc, argv, NULL);
392 }
393 
394 static void destroy_log_context(struct log_c *lc)
395 {
396 	vfree(lc->sync_bits);
397 	vfree(lc->recovering_bits);
398 	kfree(lc);
399 }
400 
401 static void core_dtr(struct dirty_log *log)
402 {
403 	struct log_c *lc = (struct log_c *) log->context;
404 
405 	vfree(lc->clean_bits);
406 	destroy_log_context(lc);
407 }
408 
409 /*----------------------------------------------------------------
410  * disk log constructor/destructor
411  *
412  * argv contains log_device region_size followed optionally by [no]sync
413  *--------------------------------------------------------------*/
414 static int disk_ctr(struct dirty_log *log, struct dm_target *ti,
415 		    unsigned int argc, char **argv)
416 {
417 	int r;
418 	struct dm_dev *dev;
419 
420 	if (argc < 2 || argc > 3) {
421 		DMWARN("wrong number of arguments to disk mirror log");
422 		return -EINVAL;
423 	}
424 
425 	r = dm_get_device(ti, argv[0], 0, 0 /* FIXME */,
426 			  FMODE_READ | FMODE_WRITE, &dev);
427 	if (r)
428 		return r;
429 
430 	r = create_log_context(log, ti, argc - 1, argv + 1, dev);
431 	if (r) {
432 		dm_put_device(ti, dev);
433 		return r;
434 	}
435 
436 	return 0;
437 }
438 
439 static void disk_dtr(struct dirty_log *log)
440 {
441 	struct log_c *lc = (struct log_c *) log->context;
442 
443 	dm_put_device(lc->ti, lc->log_dev);
444 	vfree(lc->disk_header);
445 	dm_io_client_destroy(lc->io_req.client);
446 	destroy_log_context(lc);
447 }
448 
449 static int count_bits32(uint32_t *addr, unsigned size)
450 {
451 	int count = 0, i;
452 
453 	for (i = 0; i < size; i++) {
454 		count += hweight32(*(addr+i));
455 	}
456 	return count;
457 }
458 
459 static void fail_log_device(struct log_c *lc)
460 {
461 	if (lc->log_dev_failed)
462 		return;
463 
464 	lc->log_dev_failed = 1;
465 	dm_table_event(lc->ti->table);
466 }
467 
468 static int disk_resume(struct dirty_log *log)
469 {
470 	int r;
471 	unsigned i;
472 	struct log_c *lc = (struct log_c *) log->context;
473 	size_t size = lc->bitset_uint32_count * sizeof(uint32_t);
474 
475 	/* read the disk header */
476 	r = read_header(lc);
477 	if (r) {
478 		DMWARN("%s: Failed to read header on mirror log device",
479 		       lc->log_dev->name);
480 		fail_log_device(lc);
481 		/*
482 		 * If the log device cannot be read, we must assume
483 		 * all regions are out-of-sync.  If we simply return
484 		 * here, the state will be uninitialized and could
485 		 * lead us to return 'in-sync' status for regions
486 		 * that are actually 'out-of-sync'.
487 		 */
488 		lc->header.nr_regions = 0;
489 	}
490 
491 	/* set or clear any new bits -- device has grown */
492 	if (lc->sync == NOSYNC)
493 		for (i = lc->header.nr_regions; i < lc->region_count; i++)
494 			/* FIXME: amazingly inefficient */
495 			log_set_bit(lc, lc->clean_bits, i);
496 	else
497 		for (i = lc->header.nr_regions; i < lc->region_count; i++)
498 			/* FIXME: amazingly inefficient */
499 			log_clear_bit(lc, lc->clean_bits, i);
500 
501 	/* clear any old bits -- device has shrunk */
502 	for (i = lc->region_count; i % (sizeof(*lc->clean_bits) << BYTE_SHIFT); i++)
503 		log_clear_bit(lc, lc->clean_bits, i);
504 
505 	/* copy clean across to sync */
506 	memcpy(lc->sync_bits, lc->clean_bits, size);
507 	lc->sync_count = count_bits32(lc->clean_bits, lc->bitset_uint32_count);
508 	lc->sync_search = 0;
509 
510 	/* set the correct number of regions in the header */
511 	lc->header.nr_regions = lc->region_count;
512 
513 	/* write the new header */
514 	r = write_header(lc);
515 	if (r) {
516 		DMWARN("%s: Failed to write header on mirror log device",
517 		       lc->log_dev->name);
518 		fail_log_device(lc);
519 	}
520 
521 	return r;
522 }
523 
524 static uint32_t core_get_region_size(struct dirty_log *log)
525 {
526 	struct log_c *lc = (struct log_c *) log->context;
527 	return lc->region_size;
528 }
529 
530 static int core_resume(struct dirty_log *log)
531 {
532 	struct log_c *lc = (struct log_c *) log->context;
533 	lc->sync_search = 0;
534 	return 0;
535 }
536 
537 static int core_is_clean(struct dirty_log *log, region_t region)
538 {
539 	struct log_c *lc = (struct log_c *) log->context;
540 	return log_test_bit(lc->clean_bits, region);
541 }
542 
543 static int core_in_sync(struct dirty_log *log, region_t region, int block)
544 {
545 	struct log_c *lc = (struct log_c *) log->context;
546 	return log_test_bit(lc->sync_bits, region);
547 }
548 
549 static int core_flush(struct dirty_log *log)
550 {
551 	/* no op */
552 	return 0;
553 }
554 
555 static int disk_flush(struct dirty_log *log)
556 {
557 	int r;
558 	struct log_c *lc = (struct log_c *) log->context;
559 
560 	/* only write if the log has changed */
561 	if (!lc->touched)
562 		return 0;
563 
564 	r = write_header(lc);
565 	if (r)
566 		fail_log_device(lc);
567 	else
568 		lc->touched = 0;
569 
570 	return r;
571 }
572 
573 static void core_mark_region(struct dirty_log *log, region_t region)
574 {
575 	struct log_c *lc = (struct log_c *) log->context;
576 	log_clear_bit(lc, lc->clean_bits, region);
577 }
578 
579 static void core_clear_region(struct dirty_log *log, region_t region)
580 {
581 	struct log_c *lc = (struct log_c *) log->context;
582 	log_set_bit(lc, lc->clean_bits, region);
583 }
584 
585 static int core_get_resync_work(struct dirty_log *log, region_t *region)
586 {
587 	struct log_c *lc = (struct log_c *) log->context;
588 
589 	if (lc->sync_search >= lc->region_count)
590 		return 0;
591 
592 	do {
593 		*region = ext2_find_next_zero_bit(
594 					     (unsigned long *) lc->sync_bits,
595 					     lc->region_count,
596 					     lc->sync_search);
597 		lc->sync_search = *region + 1;
598 
599 		if (*region >= lc->region_count)
600 			return 0;
601 
602 	} while (log_test_bit(lc->recovering_bits, *region));
603 
604 	log_set_bit(lc, lc->recovering_bits, *region);
605 	return 1;
606 }
607 
608 static void core_set_region_sync(struct dirty_log *log, region_t region,
609 				 int in_sync)
610 {
611 	struct log_c *lc = (struct log_c *) log->context;
612 
613 	log_clear_bit(lc, lc->recovering_bits, region);
614 	if (in_sync) {
615 		log_set_bit(lc, lc->sync_bits, region);
616                 lc->sync_count++;
617         } else if (log_test_bit(lc->sync_bits, region)) {
618 		lc->sync_count--;
619 		log_clear_bit(lc, lc->sync_bits, region);
620 	}
621 }
622 
623 static region_t core_get_sync_count(struct dirty_log *log)
624 {
625         struct log_c *lc = (struct log_c *) log->context;
626 
627         return lc->sync_count;
628 }
629 
630 #define	DMEMIT_SYNC \
631 	if (lc->sync != DEFAULTSYNC) \
632 		DMEMIT("%ssync ", lc->sync == NOSYNC ? "no" : "")
633 
634 static int core_status(struct dirty_log *log, status_type_t status,
635 		       char *result, unsigned int maxlen)
636 {
637 	int sz = 0;
638 	struct log_c *lc = log->context;
639 
640 	switch(status) {
641 	case STATUSTYPE_INFO:
642 		DMEMIT("1 %s", log->type->name);
643 		break;
644 
645 	case STATUSTYPE_TABLE:
646 		DMEMIT("%s %u %u ", log->type->name,
647 		       lc->sync == DEFAULTSYNC ? 1 : 2, lc->region_size);
648 		DMEMIT_SYNC;
649 	}
650 
651 	return sz;
652 }
653 
654 static int disk_status(struct dirty_log *log, status_type_t status,
655 		       char *result, unsigned int maxlen)
656 {
657 	int sz = 0;
658 	struct log_c *lc = log->context;
659 
660 	switch(status) {
661 	case STATUSTYPE_INFO:
662 		DMEMIT("3 %s %s %c", log->type->name, lc->log_dev->name,
663 		       lc->log_dev_failed ? 'D' : 'A');
664 		break;
665 
666 	case STATUSTYPE_TABLE:
667 		DMEMIT("%s %u %s %u ", log->type->name,
668 		       lc->sync == DEFAULTSYNC ? 2 : 3, lc->log_dev->name,
669 		       lc->region_size);
670 		DMEMIT_SYNC;
671 	}
672 
673 	return sz;
674 }
675 
676 static struct dirty_log_type _core_type = {
677 	.name = "core",
678 	.module = THIS_MODULE,
679 	.ctr = core_ctr,
680 	.dtr = core_dtr,
681 	.resume = core_resume,
682 	.get_region_size = core_get_region_size,
683 	.is_clean = core_is_clean,
684 	.in_sync = core_in_sync,
685 	.flush = core_flush,
686 	.mark_region = core_mark_region,
687 	.clear_region = core_clear_region,
688 	.get_resync_work = core_get_resync_work,
689 	.set_region_sync = core_set_region_sync,
690 	.get_sync_count = core_get_sync_count,
691 	.status = core_status,
692 };
693 
694 static struct dirty_log_type _disk_type = {
695 	.name = "disk",
696 	.module = THIS_MODULE,
697 	.ctr = disk_ctr,
698 	.dtr = disk_dtr,
699 	.suspend = disk_flush,
700 	.resume = disk_resume,
701 	.get_region_size = core_get_region_size,
702 	.is_clean = core_is_clean,
703 	.in_sync = core_in_sync,
704 	.flush = disk_flush,
705 	.mark_region = core_mark_region,
706 	.clear_region = core_clear_region,
707 	.get_resync_work = core_get_resync_work,
708 	.set_region_sync = core_set_region_sync,
709 	.get_sync_count = core_get_sync_count,
710 	.status = disk_status,
711 };
712 
713 int __init dm_dirty_log_init(void)
714 {
715 	int r;
716 
717 	r = dm_register_dirty_log_type(&_core_type);
718 	if (r)
719 		DMWARN("couldn't register core log");
720 
721 	r = dm_register_dirty_log_type(&_disk_type);
722 	if (r) {
723 		DMWARN("couldn't register disk type");
724 		dm_unregister_dirty_log_type(&_core_type);
725 	}
726 
727 	return r;
728 }
729 
730 void dm_dirty_log_exit(void)
731 {
732 	dm_unregister_dirty_log_type(&_disk_type);
733 	dm_unregister_dirty_log_type(&_core_type);
734 }
735 
736 EXPORT_SYMBOL(dm_register_dirty_log_type);
737 EXPORT_SYMBOL(dm_unregister_dirty_log_type);
738 EXPORT_SYMBOL(dm_create_dirty_log);
739 EXPORT_SYMBOL(dm_destroy_dirty_log);
740