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1 | /* | |
2 | raid0.c : Multiple Devices driver for Linux | |
3 | Copyright (C) 1994-96 Marc ZYNGIER | |
4 | <zyngier@ufr-info-p7.ibp.fr> or | |
5 | <maz@gloups.fdn.fr> | |
6 | Copyright (C) 1999, 2000 Ingo Molnar, Red Hat | |
7 | ||
8 | ||
9 | RAID-0 management functions. | |
10 | ||
11 | This program is free software; you can redistribute it and/or modify | |
12 | it under the terms of the GNU General Public License as published by | |
13 | the Free Software Foundation; either version 2, or (at your option) | |
14 | any later version. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
17 | (for example /usr/src/linux/COPYING); if not, write to the Free | |
18 | Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
19 | */ | |
20 | ||
21 | #include <linux/module.h> | |
22 | #include <linux/raid/raid0.h> | |
23 | ||
24 | #define MAJOR_NR MD_MAJOR | |
25 | #define MD_DRIVER | |
26 | #define MD_PERSONALITY | |
27 | ||
28 | static void raid0_unplug(request_queue_t *q) | |
29 | { | |
30 | mddev_t *mddev = q->queuedata; | |
31 | raid0_conf_t *conf = mddev_to_conf(mddev); | |
32 | mdk_rdev_t **devlist = conf->strip_zone[0].dev; | |
33 | int i; | |
34 | ||
35 | for (i=0; i<mddev->raid_disks; i++) { | |
36 | request_queue_t *r_queue = bdev_get_queue(devlist[i]->bdev); | |
37 | ||
38 | if (r_queue->unplug_fn) | |
39 | r_queue->unplug_fn(r_queue); | |
40 | } | |
41 | } | |
42 | ||
43 | static int raid0_issue_flush(request_queue_t *q, struct gendisk *disk, | |
44 | sector_t *error_sector) | |
45 | { | |
46 | mddev_t *mddev = q->queuedata; | |
47 | raid0_conf_t *conf = mddev_to_conf(mddev); | |
48 | mdk_rdev_t **devlist = conf->strip_zone[0].dev; | |
49 | int i, ret = 0; | |
50 | ||
51 | for (i=0; i<mddev->raid_disks && ret == 0; i++) { | |
52 | struct block_device *bdev = devlist[i]->bdev; | |
53 | request_queue_t *r_queue = bdev_get_queue(bdev); | |
54 | ||
55 | if (!r_queue->issue_flush_fn) | |
56 | ret = -EOPNOTSUPP; | |
57 | else | |
58 | ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk, error_sector); | |
59 | } | |
60 | return ret; | |
61 | } | |
62 | ||
63 | ||
64 | static int create_strip_zones (mddev_t *mddev) | |
65 | { | |
66 | int i, c, j; | |
67 | sector_t current_offset, curr_zone_offset; | |
68 | sector_t min_spacing; | |
69 | raid0_conf_t *conf = mddev_to_conf(mddev); | |
70 | mdk_rdev_t *smallest, *rdev1, *rdev2, *rdev; | |
71 | struct list_head *tmp1, *tmp2; | |
72 | struct strip_zone *zone; | |
73 | int cnt; | |
74 | char b[BDEVNAME_SIZE]; | |
75 | ||
76 | /* | |
77 | * The number of 'same size groups' | |
78 | */ | |
79 | conf->nr_strip_zones = 0; | |
80 | ||
81 | ITERATE_RDEV(mddev,rdev1,tmp1) { | |
82 | printk("raid0: looking at %s\n", | |
83 | bdevname(rdev1->bdev,b)); | |
84 | c = 0; | |
85 | ITERATE_RDEV(mddev,rdev2,tmp2) { | |
86 | printk("raid0: comparing %s(%llu)", | |
87 | bdevname(rdev1->bdev,b), | |
88 | (unsigned long long)rdev1->size); | |
89 | printk(" with %s(%llu)\n", | |
90 | bdevname(rdev2->bdev,b), | |
91 | (unsigned long long)rdev2->size); | |
92 | if (rdev2 == rdev1) { | |
93 | printk("raid0: END\n"); | |
94 | break; | |
95 | } | |
96 | if (rdev2->size == rdev1->size) | |
97 | { | |
98 | /* | |
99 | * Not unique, don't count it as a new | |
100 | * group | |
101 | */ | |
102 | printk("raid0: EQUAL\n"); | |
103 | c = 1; | |
104 | break; | |
105 | } | |
106 | printk("raid0: NOT EQUAL\n"); | |
107 | } | |
108 | if (!c) { | |
109 | printk("raid0: ==> UNIQUE\n"); | |
110 | conf->nr_strip_zones++; | |
111 | printk("raid0: %d zones\n", conf->nr_strip_zones); | |
112 | } | |
113 | } | |
114 | printk("raid0: FINAL %d zones\n", conf->nr_strip_zones); | |
115 | ||
116 | conf->strip_zone = kmalloc(sizeof(struct strip_zone)* | |
117 | conf->nr_strip_zones, GFP_KERNEL); | |
118 | if (!conf->strip_zone) | |
119 | return 1; | |
120 | conf->devlist = kmalloc(sizeof(mdk_rdev_t*)* | |
121 | conf->nr_strip_zones*mddev->raid_disks, | |
122 | GFP_KERNEL); | |
123 | if (!conf->devlist) | |
124 | return 1; | |
125 | ||
126 | memset(conf->strip_zone, 0,sizeof(struct strip_zone)* | |
127 | conf->nr_strip_zones); | |
128 | memset(conf->devlist, 0, | |
129 | sizeof(mdk_rdev_t*) * conf->nr_strip_zones * mddev->raid_disks); | |
130 | ||
131 | /* The first zone must contain all devices, so here we check that | |
132 | * there is a proper alignment of slots to devices and find them all | |
133 | */ | |
134 | zone = &conf->strip_zone[0]; | |
135 | cnt = 0; | |
136 | smallest = NULL; | |
137 | zone->dev = conf->devlist; | |
138 | ITERATE_RDEV(mddev, rdev1, tmp1) { | |
139 | int j = rdev1->raid_disk; | |
140 | ||
141 | if (j < 0 || j >= mddev->raid_disks) { | |
142 | printk("raid0: bad disk number %d - aborting!\n", j); | |
143 | goto abort; | |
144 | } | |
145 | if (zone->dev[j]) { | |
146 | printk("raid0: multiple devices for %d - aborting!\n", | |
147 | j); | |
148 | goto abort; | |
149 | } | |
150 | zone->dev[j] = rdev1; | |
151 | ||
152 | blk_queue_stack_limits(mddev->queue, | |
153 | rdev1->bdev->bd_disk->queue); | |
154 | /* as we don't honour merge_bvec_fn, we must never risk | |
155 | * violating it, so limit ->max_sector to one PAGE, as | |
156 | * a one page request is never in violation. | |
157 | */ | |
158 | ||
159 | if (rdev1->bdev->bd_disk->queue->merge_bvec_fn && | |
160 | mddev->queue->max_sectors > (PAGE_SIZE>>9)) | |
161 | blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9); | |
162 | ||
163 | if (!smallest || (rdev1->size <smallest->size)) | |
164 | smallest = rdev1; | |
165 | cnt++; | |
166 | } | |
167 | if (cnt != mddev->raid_disks) { | |
168 | printk("raid0: too few disks (%d of %d) - aborting!\n", | |
169 | cnt, mddev->raid_disks); | |
170 | goto abort; | |
171 | } | |
172 | zone->nb_dev = cnt; | |
173 | zone->size = smallest->size * cnt; | |
174 | zone->zone_offset = 0; | |
175 | ||
176 | current_offset = smallest->size; | |
177 | curr_zone_offset = zone->size; | |
178 | ||
179 | /* now do the other zones */ | |
180 | for (i = 1; i < conf->nr_strip_zones; i++) | |
181 | { | |
182 | zone = conf->strip_zone + i; | |
183 | zone->dev = conf->strip_zone[i-1].dev + mddev->raid_disks; | |
184 | ||
185 | printk("raid0: zone %d\n", i); | |
186 | zone->dev_offset = current_offset; | |
187 | smallest = NULL; | |
188 | c = 0; | |
189 | ||
190 | for (j=0; j<cnt; j++) { | |
191 | char b[BDEVNAME_SIZE]; | |
192 | rdev = conf->strip_zone[0].dev[j]; | |
193 | printk("raid0: checking %s ...", bdevname(rdev->bdev,b)); | |
194 | if (rdev->size > current_offset) | |
195 | { | |
196 | printk(" contained as device %d\n", c); | |
197 | zone->dev[c] = rdev; | |
198 | c++; | |
199 | if (!smallest || (rdev->size <smallest->size)) { | |
200 | smallest = rdev; | |
201 | printk(" (%llu) is smallest!.\n", | |
202 | (unsigned long long)rdev->size); | |
203 | } | |
204 | } else | |
205 | printk(" nope.\n"); | |
206 | } | |
207 | ||
208 | zone->nb_dev = c; | |
209 | zone->size = (smallest->size - current_offset) * c; | |
210 | printk("raid0: zone->nb_dev: %d, size: %llu\n", | |
211 | zone->nb_dev, (unsigned long long)zone->size); | |
212 | ||
213 | zone->zone_offset = curr_zone_offset; | |
214 | curr_zone_offset += zone->size; | |
215 | ||
216 | current_offset = smallest->size; | |
217 | printk("raid0: current zone offset: %llu\n", | |
218 | (unsigned long long)current_offset); | |
219 | } | |
220 | ||
221 | /* Now find appropriate hash spacing. | |
222 | * We want a number which causes most hash entries to cover | |
223 | * at most two strips, but the hash table must be at most | |
224 | * 1 PAGE. We choose the smallest strip, or contiguous collection | |
225 | * of strips, that has big enough size. We never consider the last | |
226 | * strip though as it's size has no bearing on the efficacy of the hash | |
227 | * table. | |
228 | */ | |
229 | conf->hash_spacing = curr_zone_offset; | |
230 | min_spacing = curr_zone_offset; | |
231 | sector_div(min_spacing, PAGE_SIZE/sizeof(struct strip_zone*)); | |
232 | for (i=0; i < conf->nr_strip_zones-1; i++) { | |
233 | sector_t sz = 0; | |
234 | for (j=i; j<conf->nr_strip_zones-1 && | |
235 | sz < min_spacing ; j++) | |
236 | sz += conf->strip_zone[j].size; | |
237 | if (sz >= min_spacing && sz < conf->hash_spacing) | |
238 | conf->hash_spacing = sz; | |
239 | } | |
240 | ||
241 | mddev->queue->unplug_fn = raid0_unplug; | |
242 | ||
243 | mddev->queue->issue_flush_fn = raid0_issue_flush; | |
244 | ||
245 | printk("raid0: done.\n"); | |
246 | return 0; | |
247 | abort: | |
248 | return 1; | |
249 | } | |
250 | ||
251 | /** | |
252 | * raid0_mergeable_bvec -- tell bio layer if a two requests can be merged | |
253 | * @q: request queue | |
254 | * @bio: the buffer head that's been built up so far | |
255 | * @biovec: the request that could be merged to it. | |
256 | * | |
257 | * Return amount of bytes we can accept at this offset | |
258 | */ | |
259 | static int raid0_mergeable_bvec(request_queue_t *q, struct bio *bio, struct bio_vec *biovec) | |
260 | { | |
261 | mddev_t *mddev = q->queuedata; | |
262 | sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev); | |
263 | int max; | |
264 | unsigned int chunk_sectors = mddev->chunk_size >> 9; | |
265 | unsigned int bio_sectors = bio->bi_size >> 9; | |
266 | ||
267 | max = (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9; | |
268 | if (max < 0) max = 0; /* bio_add cannot handle a negative return */ | |
269 | if (max <= biovec->bv_len && bio_sectors == 0) | |
270 | return biovec->bv_len; | |
271 | else | |
272 | return max; | |
273 | } | |
274 | ||
275 | static int raid0_run (mddev_t *mddev) | |
276 | { | |
277 | unsigned cur=0, i=0, nb_zone; | |
278 | s64 size; | |
279 | raid0_conf_t *conf; | |
280 | mdk_rdev_t *rdev; | |
281 | struct list_head *tmp; | |
282 | ||
283 | printk("%s: setting max_sectors to %d, segment boundary to %d\n", | |
284 | mdname(mddev), | |
285 | mddev->chunk_size >> 9, | |
286 | (mddev->chunk_size>>1)-1); | |
287 | blk_queue_max_sectors(mddev->queue, mddev->chunk_size >> 9); | |
288 | blk_queue_segment_boundary(mddev->queue, (mddev->chunk_size>>1) - 1); | |
289 | ||
290 | conf = kmalloc(sizeof (raid0_conf_t), GFP_KERNEL); | |
291 | if (!conf) | |
292 | goto out; | |
293 | mddev->private = (void *)conf; | |
294 | ||
295 | conf->strip_zone = NULL; | |
296 | conf->devlist = NULL; | |
297 | if (create_strip_zones (mddev)) | |
298 | goto out_free_conf; | |
299 | ||
300 | /* calculate array device size */ | |
301 | mddev->array_size = 0; | |
302 | ITERATE_RDEV(mddev,rdev,tmp) | |
303 | mddev->array_size += rdev->size; | |
304 | ||
305 | printk("raid0 : md_size is %llu blocks.\n", | |
306 | (unsigned long long)mddev->array_size); | |
307 | printk("raid0 : conf->hash_spacing is %llu blocks.\n", | |
308 | (unsigned long long)conf->hash_spacing); | |
309 | { | |
310 | #if __GNUC__ < 3 | |
311 | volatile | |
312 | #endif | |
313 | sector_t s = mddev->array_size; | |
314 | sector_t space = conf->hash_spacing; | |
315 | int round; | |
316 | conf->preshift = 0; | |
317 | if (sizeof(sector_t) > sizeof(u32)) { | |
318 | /*shift down space and s so that sector_div will work */ | |
319 | while (space > (sector_t) (~(u32)0)) { | |
320 | s >>= 1; | |
321 | space >>= 1; | |
322 | s += 1; /* force round-up */ | |
323 | conf->preshift++; | |
324 | } | |
325 | } | |
326 | round = sector_div(s, (u32)space) ? 1 : 0; | |
327 | nb_zone = s + round; | |
328 | } | |
329 | printk("raid0 : nb_zone is %d.\n", nb_zone); | |
330 | ||
331 | printk("raid0 : Allocating %Zd bytes for hash.\n", | |
332 | nb_zone*sizeof(struct strip_zone*)); | |
333 | conf->hash_table = kmalloc (sizeof (struct strip_zone *)*nb_zone, GFP_KERNEL); | |
334 | if (!conf->hash_table) | |
335 | goto out_free_conf; | |
336 | size = conf->strip_zone[cur].size; | |
337 | ||
338 | for (i=0; i< nb_zone; i++) { | |
339 | conf->hash_table[i] = conf->strip_zone + cur; | |
340 | while (size <= conf->hash_spacing) { | |
341 | cur++; | |
342 | size += conf->strip_zone[cur].size; | |
343 | } | |
344 | size -= conf->hash_spacing; | |
345 | } | |
346 | if (conf->preshift) { | |
347 | conf->hash_spacing >>= conf->preshift; | |
348 | /* round hash_spacing up so when we divide by it, we | |
349 | * err on the side of too-low, which is safest | |
350 | */ | |
351 | conf->hash_spacing++; | |
352 | } | |
353 | ||
354 | /* calculate the max read-ahead size. | |
355 | * For read-ahead of large files to be effective, we need to | |
356 | * readahead at least twice a whole stripe. i.e. number of devices | |
357 | * multiplied by chunk size times 2. | |
358 | * If an individual device has an ra_pages greater than the | |
359 | * chunk size, then we will not drive that device as hard as it | |
360 | * wants. We consider this a configuration error: a larger | |
361 | * chunksize should be used in that case. | |
362 | */ | |
363 | { | |
364 | int stripe = mddev->raid_disks * mddev->chunk_size / PAGE_CACHE_SIZE; | |
365 | if (mddev->queue->backing_dev_info.ra_pages < 2* stripe) | |
366 | mddev->queue->backing_dev_info.ra_pages = 2* stripe; | |
367 | } | |
368 | ||
369 | ||
370 | blk_queue_merge_bvec(mddev->queue, raid0_mergeable_bvec); | |
371 | return 0; | |
372 | ||
373 | out_free_conf: | |
374 | kfree(conf->strip_zone); | |
375 | kfree(conf->devlist); | |
376 | kfree(conf); | |
377 | mddev->private = NULL; | |
378 | out: | |
379 | return 1; | |
380 | } | |
381 | ||
382 | static int raid0_stop (mddev_t *mddev) | |
383 | { | |
384 | raid0_conf_t *conf = mddev_to_conf(mddev); | |
385 | ||
386 | blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/ | |
387 | kfree(conf->hash_table); | |
388 | conf->hash_table = NULL; | |
389 | kfree(conf->strip_zone); | |
390 | conf->strip_zone = NULL; | |
391 | kfree(conf); | |
392 | mddev->private = NULL; | |
393 | ||
394 | return 0; | |
395 | } | |
396 | ||
397 | static int raid0_make_request (request_queue_t *q, struct bio *bio) | |
398 | { | |
399 | mddev_t *mddev = q->queuedata; | |
400 | unsigned int sect_in_chunk, chunksize_bits, chunk_size, chunk_sects; | |
401 | raid0_conf_t *conf = mddev_to_conf(mddev); | |
402 | struct strip_zone *zone; | |
403 | mdk_rdev_t *tmp_dev; | |
404 | unsigned long chunk; | |
405 | sector_t block, rsect; | |
406 | ||
407 | if (unlikely(bio_barrier(bio))) { | |
408 | bio_endio(bio, bio->bi_size, -EOPNOTSUPP); | |
409 | return 0; | |
410 | } | |
411 | ||
412 | if (bio_data_dir(bio)==WRITE) { | |
413 | disk_stat_inc(mddev->gendisk, writes); | |
414 | disk_stat_add(mddev->gendisk, write_sectors, bio_sectors(bio)); | |
415 | } else { | |
416 | disk_stat_inc(mddev->gendisk, reads); | |
417 | disk_stat_add(mddev->gendisk, read_sectors, bio_sectors(bio)); | |
418 | } | |
419 | ||
420 | chunk_size = mddev->chunk_size >> 10; | |
421 | chunk_sects = mddev->chunk_size >> 9; | |
422 | chunksize_bits = ffz(~chunk_size); | |
423 | block = bio->bi_sector >> 1; | |
424 | ||
425 | ||
426 | if (unlikely(chunk_sects < (bio->bi_sector & (chunk_sects - 1)) + (bio->bi_size >> 9))) { | |
427 | struct bio_pair *bp; | |
428 | /* Sanity check -- queue functions should prevent this happening */ | |
429 | if (bio->bi_vcnt != 1 || | |
430 | bio->bi_idx != 0) | |
431 | goto bad_map; | |
432 | /* This is a one page bio that upper layers | |
433 | * refuse to split for us, so we need to split it. | |
434 | */ | |
435 | bp = bio_split(bio, bio_split_pool, chunk_sects - (bio->bi_sector & (chunk_sects - 1)) ); | |
436 | if (raid0_make_request(q, &bp->bio1)) | |
437 | generic_make_request(&bp->bio1); | |
438 | if (raid0_make_request(q, &bp->bio2)) | |
439 | generic_make_request(&bp->bio2); | |
440 | ||
441 | bio_pair_release(bp); | |
442 | return 0; | |
443 | } | |
444 | ||
445 | ||
446 | { | |
447 | #if __GNUC__ < 3 | |
448 | volatile | |
449 | #endif | |
450 | sector_t x = block >> conf->preshift; | |
451 | sector_div(x, (u32)conf->hash_spacing); | |
452 | zone = conf->hash_table[x]; | |
453 | } | |
454 | ||
455 | while (block >= (zone->zone_offset + zone->size)) | |
456 | zone++; | |
457 | ||
458 | sect_in_chunk = bio->bi_sector & ((chunk_size<<1) -1); | |
459 | ||
460 | ||
461 | { | |
462 | sector_t x = (block - zone->zone_offset) >> chunksize_bits; | |
463 | ||
464 | sector_div(x, zone->nb_dev); | |
465 | chunk = x; | |
466 | BUG_ON(x != (sector_t)chunk); | |
467 | ||
468 | x = block >> chunksize_bits; | |
469 | tmp_dev = zone->dev[sector_div(x, zone->nb_dev)]; | |
470 | } | |
471 | rsect = (((chunk << chunksize_bits) + zone->dev_offset)<<1) | |
472 | + sect_in_chunk; | |
473 | ||
474 | bio->bi_bdev = tmp_dev->bdev; | |
475 | bio->bi_sector = rsect + tmp_dev->data_offset; | |
476 | ||
477 | /* | |
478 | * Let the main block layer submit the IO and resolve recursion: | |
479 | */ | |
480 | return 1; | |
481 | ||
482 | bad_map: | |
483 | printk("raid0_make_request bug: can't convert block across chunks" | |
484 | " or bigger than %dk %llu %d\n", chunk_size, | |
485 | (unsigned long long)bio->bi_sector, bio->bi_size >> 10); | |
486 | ||
487 | bio_io_error(bio, bio->bi_size); | |
488 | return 0; | |
489 | } | |
490 | ||
491 | static void raid0_status (struct seq_file *seq, mddev_t *mddev) | |
492 | { | |
493 | #undef MD_DEBUG | |
494 | #ifdef MD_DEBUG | |
495 | int j, k, h; | |
496 | char b[BDEVNAME_SIZE]; | |
497 | raid0_conf_t *conf = mddev_to_conf(mddev); | |
498 | ||
499 | h = 0; | |
500 | for (j = 0; j < conf->nr_strip_zones; j++) { | |
501 | seq_printf(seq, " z%d", j); | |
502 | if (conf->hash_table[h] == conf->strip_zone+j) | |
503 | seq_printf("(h%d)", h++); | |
504 | seq_printf(seq, "=["); | |
505 | for (k = 0; k < conf->strip_zone[j].nb_dev; k++) | |
506 | seq_printf (seq, "%s/", bdevname( | |
507 | conf->strip_zone[j].dev[k]->bdev,b)); | |
508 | ||
509 | seq_printf (seq, "] zo=%d do=%d s=%d\n", | |
510 | conf->strip_zone[j].zone_offset, | |
511 | conf->strip_zone[j].dev_offset, | |
512 | conf->strip_zone[j].size); | |
513 | } | |
514 | #endif | |
515 | seq_printf(seq, " %dk chunks", mddev->chunk_size/1024); | |
516 | return; | |
517 | } | |
518 | ||
519 | static mdk_personality_t raid0_personality= | |
520 | { | |
521 | .name = "raid0", | |
522 | .owner = THIS_MODULE, | |
523 | .make_request = raid0_make_request, | |
524 | .run = raid0_run, | |
525 | .stop = raid0_stop, | |
526 | .status = raid0_status, | |
527 | }; | |
528 | ||
529 | static int __init raid0_init (void) | |
530 | { | |
531 | return register_md_personality (RAID0, &raid0_personality); | |
532 | } | |
533 | ||
534 | static void raid0_exit (void) | |
535 | { | |
536 | unregister_md_personality (RAID0); | |
537 | } | |
538 | ||
539 | module_init(raid0_init); | |
540 | module_exit(raid0_exit); | |
541 | MODULE_LICENSE("GPL"); | |
542 | MODULE_ALIAS("md-personality-2"); /* RAID0 */ |