Merge branch 'for-linus' of git://git.o-hand.com/linux-rpurdie-backlight
[linux-2.6] / drivers / md / dm-log.c
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);