xref: /openbmc/linux/drivers/md/raid0.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
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 	const int rw = bio_data_dir(bio);
407 
408 	if (unlikely(bio_barrier(bio))) {
409 		bio_endio(bio, bio->bi_size, -EOPNOTSUPP);
410 		return 0;
411 	}
412 
413 	disk_stat_inc(mddev->gendisk, ios[rw]);
414 	disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bio));
415 
416 	chunk_size = mddev->chunk_size >> 10;
417 	chunk_sects = mddev->chunk_size >> 9;
418 	chunksize_bits = ffz(~chunk_size);
419 	block = bio->bi_sector >> 1;
420 
421 
422 	if (unlikely(chunk_sects < (bio->bi_sector & (chunk_sects - 1)) + (bio->bi_size >> 9))) {
423 		struct bio_pair *bp;
424 		/* Sanity check -- queue functions should prevent this happening */
425 		if (bio->bi_vcnt != 1 ||
426 		    bio->bi_idx != 0)
427 			goto bad_map;
428 		/* This is a one page bio that upper layers
429 		 * refuse to split for us, so we need to split it.
430 		 */
431 		bp = bio_split(bio, bio_split_pool, chunk_sects - (bio->bi_sector & (chunk_sects - 1)) );
432 		if (raid0_make_request(q, &bp->bio1))
433 			generic_make_request(&bp->bio1);
434 		if (raid0_make_request(q, &bp->bio2))
435 			generic_make_request(&bp->bio2);
436 
437 		bio_pair_release(bp);
438 		return 0;
439 	}
440 
441 
442 	{
443 #if __GNUC__ < 3
444 		volatile
445 #endif
446 		sector_t x = block >> conf->preshift;
447 		sector_div(x, (u32)conf->hash_spacing);
448 		zone = conf->hash_table[x];
449 	}
450 
451 	while (block >= (zone->zone_offset + zone->size))
452 		zone++;
453 
454 	sect_in_chunk = bio->bi_sector & ((chunk_size<<1) -1);
455 
456 
457 	{
458 		sector_t x =  (block - zone->zone_offset) >> chunksize_bits;
459 
460 		sector_div(x, zone->nb_dev);
461 		chunk = x;
462 		BUG_ON(x != (sector_t)chunk);
463 
464 		x = block >> chunksize_bits;
465 		tmp_dev = zone->dev[sector_div(x, zone->nb_dev)];
466 	}
467 	rsect = (((chunk << chunksize_bits) + zone->dev_offset)<<1)
468 		+ sect_in_chunk;
469 
470 	bio->bi_bdev = tmp_dev->bdev;
471 	bio->bi_sector = rsect + tmp_dev->data_offset;
472 
473 	/*
474 	 * Let the main block layer submit the IO and resolve recursion:
475 	 */
476 	return 1;
477 
478 bad_map:
479 	printk("raid0_make_request bug: can't convert block across chunks"
480 		" or bigger than %dk %llu %d\n", chunk_size,
481 		(unsigned long long)bio->bi_sector, bio->bi_size >> 10);
482 
483 	bio_io_error(bio, bio->bi_size);
484 	return 0;
485 }
486 
487 static void raid0_status (struct seq_file *seq, mddev_t *mddev)
488 {
489 #undef MD_DEBUG
490 #ifdef MD_DEBUG
491 	int j, k, h;
492 	char b[BDEVNAME_SIZE];
493 	raid0_conf_t *conf = mddev_to_conf(mddev);
494 
495 	h = 0;
496 	for (j = 0; j < conf->nr_strip_zones; j++) {
497 		seq_printf(seq, "      z%d", j);
498 		if (conf->hash_table[h] == conf->strip_zone+j)
499 			seq_printf("(h%d)", h++);
500 		seq_printf(seq, "=[");
501 		for (k = 0; k < conf->strip_zone[j].nb_dev; k++)
502 			seq_printf (seq, "%s/", bdevname(
503 				conf->strip_zone[j].dev[k]->bdev,b));
504 
505 		seq_printf (seq, "] zo=%d do=%d s=%d\n",
506 				conf->strip_zone[j].zone_offset,
507 				conf->strip_zone[j].dev_offset,
508 				conf->strip_zone[j].size);
509 	}
510 #endif
511 	seq_printf(seq, " %dk chunks", mddev->chunk_size/1024);
512 	return;
513 }
514 
515 static mdk_personality_t raid0_personality=
516 {
517 	.name		= "raid0",
518 	.owner		= THIS_MODULE,
519 	.make_request	= raid0_make_request,
520 	.run		= raid0_run,
521 	.stop		= raid0_stop,
522 	.status		= raid0_status,
523 };
524 
525 static int __init raid0_init (void)
526 {
527 	return register_md_personality (RAID0, &raid0_personality);
528 }
529 
530 static void raid0_exit (void)
531 {
532 	unregister_md_personality (RAID0);
533 }
534 
535 module_init(raid0_init);
536 module_exit(raid0_exit);
537 MODULE_LICENSE("GPL");
538 MODULE_ALIAS("md-personality-2"); /* RAID0 */
539