[PATCH] dm mirror log: refactor context
[linux-2.6.git] / 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 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
160 /*
161  * The touched member needs to be updated every time we access
162  * one of the bitsets.
163  */
164 static  inline int log_test_bit(uint32_t *bs, unsigned bit)
165 {
166         return ext2_test_bit(bit, (unsigned long *) bs) ? 1 : 0;
167 }
168
169 static inline void log_set_bit(struct log_c *l,
170                                uint32_t *bs, unsigned bit)
171 {
172         ext2_set_bit(bit, (unsigned long *) bs);
173         l->touched = 1;
174 }
175
176 static inline void log_clear_bit(struct log_c *l,
177                                  uint32_t *bs, unsigned bit)
178 {
179         ext2_clear_bit(bit, (unsigned long *) bs);
180         l->touched = 1;
181 }
182
183 /*----------------------------------------------------------------
184  * Header IO
185  *--------------------------------------------------------------*/
186 static void header_to_disk(struct log_header *core, struct log_header *disk)
187 {
188         disk->magic = cpu_to_le32(core->magic);
189         disk->version = cpu_to_le32(core->version);
190         disk->nr_regions = cpu_to_le64(core->nr_regions);
191 }
192
193 static void header_from_disk(struct log_header *core, struct log_header *disk)
194 {
195         core->magic = le32_to_cpu(disk->magic);
196         core->version = le32_to_cpu(disk->version);
197         core->nr_regions = le64_to_cpu(disk->nr_regions);
198 }
199
200 static int read_header(struct log_c *log)
201 {
202         int r;
203         unsigned long ebits;
204
205         r = dm_io_sync_vm(1, &log->header_location, READ,
206                           log->disk_header, &ebits);
207         if (r)
208                 return r;
209
210         header_from_disk(&log->header, log->disk_header);
211
212         /* New log required? */
213         if (log->sync != DEFAULTSYNC || log->header.magic != MIRROR_MAGIC) {
214                 log->header.magic = MIRROR_MAGIC;
215                 log->header.version = MIRROR_DISK_VERSION;
216                 log->header.nr_regions = 0;
217         }
218
219 #ifdef __LITTLE_ENDIAN
220         if (log->header.version == 1)
221                 log->header.version = 2;
222 #endif
223
224         if (log->header.version != MIRROR_DISK_VERSION) {
225                 DMWARN("incompatible disk log version");
226                 return -EINVAL;
227         }
228
229         return 0;
230 }
231
232 static inline int write_header(struct log_c *log)
233 {
234         unsigned long ebits;
235
236         header_to_disk(&log->header, log->disk_header);
237         return dm_io_sync_vm(1, &log->header_location, WRITE,
238                              log->disk_header, &ebits);
239 }
240
241 /*----------------------------------------------------------------
242  * core log constructor/destructor
243  *
244  * argv contains region_size followed optionally by [no]sync
245  *--------------------------------------------------------------*/
246 #define BYTE_SHIFT 3
247 static int create_log_context(struct dirty_log *log, struct dm_target *ti,
248                               unsigned int argc, char **argv,
249                               struct dm_dev *dev)
250 {
251         enum sync sync = DEFAULTSYNC;
252
253         struct log_c *lc;
254         uint32_t region_size;
255         unsigned int region_count;
256         size_t bitset_size, buf_size;
257
258         if (argc < 1 || argc > 2) {
259                 DMWARN("wrong number of arguments to mirror log");
260                 return -EINVAL;
261         }
262
263         if (argc > 1) {
264                 if (!strcmp(argv[1], "sync"))
265                         sync = FORCESYNC;
266                 else if (!strcmp(argv[1], "nosync"))
267                         sync = NOSYNC;
268                 else {
269                         DMWARN("unrecognised sync argument to mirror log: %s",
270                                argv[1]);
271                         return -EINVAL;
272                 }
273         }
274
275         if (sscanf(argv[0], "%u", &region_size) != 1) {
276                 DMWARN("invalid region size string");
277                 return -EINVAL;
278         }
279
280         region_count = dm_sector_div_up(ti->len, region_size);
281
282         lc = kmalloc(sizeof(*lc), GFP_KERNEL);
283         if (!lc) {
284                 DMWARN("couldn't allocate core log");
285                 return -ENOMEM;
286         }
287
288         lc->ti = ti;
289         lc->touched = 0;
290         lc->region_size = region_size;
291         lc->region_count = region_count;
292         lc->sync = sync;
293
294         /*
295          * Work out how many "unsigned long"s we need to hold the bitset.
296          */
297         bitset_size = dm_round_up(region_count,
298                                   sizeof(unsigned long) << BYTE_SHIFT);
299         bitset_size >>= BYTE_SHIFT;
300
301         lc->bitset_uint32_count = bitset_size / 4;
302
303         /*
304          * Disk log?
305          */
306         if (!dev) {
307                 lc->clean_bits = vmalloc(bitset_size);
308                 if (!lc->clean_bits) {
309                         DMWARN("couldn't allocate clean bitset");
310                         kfree(lc);
311                         return -ENOMEM;
312                 }
313                 lc->disk_header = NULL;
314         } else {
315                 lc->log_dev = dev;
316                 lc->header_location.bdev = lc->log_dev->bdev;
317                 lc->header_location.sector = 0;
318
319                 /*
320                  * Buffer holds both header and bitset.
321                  */
322                 buf_size = dm_round_up((LOG_OFFSET << SECTOR_SHIFT) +
323                                        bitset_size, ti->limits.hardsect_size);
324                 lc->header_location.count = buf_size >> SECTOR_SHIFT;
325
326                 lc->disk_header = vmalloc(buf_size);
327                 if (!lc->disk_header) {
328                         DMWARN("couldn't allocate disk log buffer");
329                         kfree(lc);
330                         return -ENOMEM;
331                 }
332
333                 lc->clean_bits = (void *)lc->disk_header +
334                                  (LOG_OFFSET << SECTOR_SHIFT);
335         }
336
337         memset(lc->clean_bits, -1, bitset_size);
338
339         lc->sync_bits = vmalloc(bitset_size);
340         if (!lc->sync_bits) {
341                 DMWARN("couldn't allocate sync bitset");
342                 if (!dev)
343                         vfree(lc->clean_bits);
344                 vfree(lc->disk_header);
345                 kfree(lc);
346                 return -ENOMEM;
347         }
348         memset(lc->sync_bits, (sync == NOSYNC) ? -1 : 0, bitset_size);
349         lc->sync_count = (sync == NOSYNC) ? region_count : 0;
350
351         lc->recovering_bits = vmalloc(bitset_size);
352         if (!lc->recovering_bits) {
353                 DMWARN("couldn't allocate sync bitset");
354                 vfree(lc->sync_bits);
355                 if (!dev)
356                         vfree(lc->clean_bits);
357                 vfree(lc->disk_header);
358                 kfree(lc);
359                 return -ENOMEM;
360         }
361         memset(lc->recovering_bits, 0, bitset_size);
362         lc->sync_search = 0;
363         log->context = lc;
364
365         return 0;
366 }
367
368 static int core_ctr(struct dirty_log *log, struct dm_target *ti,
369                     unsigned int argc, char **argv)
370 {
371         return create_log_context(log, ti, argc, argv, NULL);
372 }
373
374 static void destroy_log_context(struct log_c *lc)
375 {
376         vfree(lc->sync_bits);
377         vfree(lc->recovering_bits);
378         kfree(lc);
379 }
380
381 static void core_dtr(struct dirty_log *log)
382 {
383         struct log_c *lc = (struct log_c *) log->context;
384
385         vfree(lc->clean_bits);
386         destroy_log_context(lc);
387 }
388
389 /*----------------------------------------------------------------
390  * disk log constructor/destructor
391  *
392  * argv contains log_device region_size followed optionally by [no]sync
393  *--------------------------------------------------------------*/
394 static int disk_ctr(struct dirty_log *log, struct dm_target *ti,
395                     unsigned int argc, char **argv)
396 {
397         int r;
398         struct dm_dev *dev;
399
400         if (argc < 2 || argc > 3) {
401                 DMWARN("wrong number of arguments to disk mirror log");
402                 return -EINVAL;
403         }
404
405         r = dm_get_device(ti, argv[0], 0, 0 /* FIXME */,
406                           FMODE_READ | FMODE_WRITE, &dev);
407         if (r)
408                 return r;
409
410         r = create_log_context(log, ti, argc - 1, argv + 1, dev);
411         if (r) {
412                 dm_put_device(ti, dev);
413                 return r;
414         }
415
416         return 0;
417 }
418
419 static void disk_dtr(struct dirty_log *log)
420 {
421         struct log_c *lc = (struct log_c *) log->context;
422
423         dm_put_device(lc->ti, lc->log_dev);
424         vfree(lc->disk_header);
425         destroy_log_context(lc);
426 }
427
428 static int count_bits32(uint32_t *addr, unsigned size)
429 {
430         int count = 0, i;
431
432         for (i = 0; i < size; i++) {
433                 count += hweight32(*(addr+i));
434         }
435         return count;
436 }
437
438 static int disk_resume(struct dirty_log *log)
439 {
440         int r;
441         unsigned i;
442         struct log_c *lc = (struct log_c *) log->context;
443         size_t size = lc->bitset_uint32_count * sizeof(uint32_t);
444
445         /* read the disk header */
446         r = read_header(lc);
447         if (r)
448                 return r;
449
450         /* set or clear any new bits */
451         if (lc->sync == NOSYNC)
452                 for (i = lc->header.nr_regions; i < lc->region_count; i++)
453                         /* FIXME: amazingly inefficient */
454                         log_set_bit(lc, lc->clean_bits, i);
455         else
456                 for (i = lc->header.nr_regions; i < lc->region_count; i++)
457                         /* FIXME: amazingly inefficient */
458                         log_clear_bit(lc, lc->clean_bits, i);
459
460         /* copy clean across to sync */
461         memcpy(lc->sync_bits, lc->clean_bits, size);
462         lc->sync_count = count_bits32(lc->clean_bits, lc->bitset_uint32_count);
463
464         /* set the correct number of regions in the header */
465         lc->header.nr_regions = lc->region_count;
466
467         /* write the new header */
468         return write_header(lc);
469 }
470
471 static uint32_t core_get_region_size(struct dirty_log *log)
472 {
473         struct log_c *lc = (struct log_c *) log->context;
474         return lc->region_size;
475 }
476
477 static int core_is_clean(struct dirty_log *log, region_t region)
478 {
479         struct log_c *lc = (struct log_c *) log->context;
480         return log_test_bit(lc->clean_bits, region);
481 }
482
483 static int core_in_sync(struct dirty_log *log, region_t region, int block)
484 {
485         struct log_c *lc = (struct log_c *) log->context;
486         return log_test_bit(lc->sync_bits, region);
487 }
488
489 static int core_flush(struct dirty_log *log)
490 {
491         /* no op */
492         return 0;
493 }
494
495 static int disk_flush(struct dirty_log *log)
496 {
497         int r;
498         struct log_c *lc = (struct log_c *) log->context;
499
500         /* only write if the log has changed */
501         if (!lc->touched)
502                 return 0;
503
504         r = write_header(lc);
505         if (!r)
506                 lc->touched = 0;
507
508         return r;
509 }
510
511 static void core_mark_region(struct dirty_log *log, region_t region)
512 {
513         struct log_c *lc = (struct log_c *) log->context;
514         log_clear_bit(lc, lc->clean_bits, region);
515 }
516
517 static void core_clear_region(struct dirty_log *log, region_t region)
518 {
519         struct log_c *lc = (struct log_c *) log->context;
520         log_set_bit(lc, lc->clean_bits, region);
521 }
522
523 static int core_get_resync_work(struct dirty_log *log, region_t *region)
524 {
525         struct log_c *lc = (struct log_c *) log->context;
526
527         if (lc->sync_search >= lc->region_count)
528                 return 0;
529
530         do {
531                 *region = ext2_find_next_zero_bit(
532                                              (unsigned long *) lc->sync_bits,
533                                              lc->region_count,
534                                              lc->sync_search);
535                 lc->sync_search = *region + 1;
536
537                 if (*region >= lc->region_count)
538                         return 0;
539
540         } while (log_test_bit(lc->recovering_bits, *region));
541
542         log_set_bit(lc, lc->recovering_bits, *region);
543         return 1;
544 }
545
546 static void core_complete_resync_work(struct dirty_log *log, region_t region,
547                                       int success)
548 {
549         struct log_c *lc = (struct log_c *) log->context;
550
551         log_clear_bit(lc, lc->recovering_bits, region);
552         if (success) {
553                 log_set_bit(lc, lc->sync_bits, region);
554                 lc->sync_count++;
555         }
556 }
557
558 static region_t core_get_sync_count(struct dirty_log *log)
559 {
560         struct log_c *lc = (struct log_c *) log->context;
561
562         return lc->sync_count;
563 }
564
565 #define DMEMIT_SYNC \
566         if (lc->sync != DEFAULTSYNC) \
567                 DMEMIT("%ssync ", lc->sync == NOSYNC ? "no" : "")
568
569 static int core_status(struct dirty_log *log, status_type_t status,
570                        char *result, unsigned int maxlen)
571 {
572         int sz = 0;
573         struct log_c *lc = log->context;
574
575         switch(status) {
576         case STATUSTYPE_INFO:
577                 break;
578
579         case STATUSTYPE_TABLE:
580                 DMEMIT("%s %u %u ", log->type->name,
581                        lc->sync == DEFAULTSYNC ? 1 : 2, lc->region_size);
582                 DMEMIT_SYNC;
583         }
584
585         return sz;
586 }
587
588 static int disk_status(struct dirty_log *log, status_type_t status,
589                        char *result, unsigned int maxlen)
590 {
591         int sz = 0;
592         char buffer[16];
593         struct log_c *lc = log->context;
594
595         switch(status) {
596         case STATUSTYPE_INFO:
597                 break;
598
599         case STATUSTYPE_TABLE:
600                 format_dev_t(buffer, lc->log_dev->bdev->bd_dev);
601                 DMEMIT("%s %u %s %u ", log->type->name,
602                        lc->sync == DEFAULTSYNC ? 2 : 3, buffer,
603                        lc->region_size);
604                 DMEMIT_SYNC;
605         }
606
607         return sz;
608 }
609
610 static struct dirty_log_type _core_type = {
611         .name = "core",
612         .module = THIS_MODULE,
613         .ctr = core_ctr,
614         .dtr = core_dtr,
615         .get_region_size = core_get_region_size,
616         .is_clean = core_is_clean,
617         .in_sync = core_in_sync,
618         .flush = core_flush,
619         .mark_region = core_mark_region,
620         .clear_region = core_clear_region,
621         .get_resync_work = core_get_resync_work,
622         .complete_resync_work = core_complete_resync_work,
623         .get_sync_count = core_get_sync_count,
624         .status = core_status,
625 };
626
627 static struct dirty_log_type _disk_type = {
628         .name = "disk",
629         .module = THIS_MODULE,
630         .ctr = disk_ctr,
631         .dtr = disk_dtr,
632         .suspend = disk_flush,
633         .resume = disk_resume,
634         .get_region_size = core_get_region_size,
635         .is_clean = core_is_clean,
636         .in_sync = core_in_sync,
637         .flush = disk_flush,
638         .mark_region = core_mark_region,
639         .clear_region = core_clear_region,
640         .get_resync_work = core_get_resync_work,
641         .complete_resync_work = core_complete_resync_work,
642         .get_sync_count = core_get_sync_count,
643         .status = disk_status,
644 };
645
646 int __init dm_dirty_log_init(void)
647 {
648         int r;
649
650         r = dm_register_dirty_log_type(&_core_type);
651         if (r)
652                 DMWARN("couldn't register core log");
653
654         r = dm_register_dirty_log_type(&_disk_type);
655         if (r) {
656                 DMWARN("couldn't register disk type");
657                 dm_unregister_dirty_log_type(&_core_type);
658         }
659
660         return r;
661 }
662
663 void dm_dirty_log_exit(void)
664 {
665         dm_unregister_dirty_log_type(&_disk_type);
666         dm_unregister_dirty_log_type(&_core_type);
667 }
668
669 EXPORT_SYMBOL(dm_register_dirty_log_type);
670 EXPORT_SYMBOL(dm_unregister_dirty_log_type);
671 EXPORT_SYMBOL(dm_create_dirty_log);
672 EXPORT_SYMBOL(dm_destroy_dirty_log);