xref: /openbmc/linux/drivers/md/raid0.c (revision 22246614)
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(struct request_queue *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 		struct request_queue *r_queue = bdev_get_queue(devlist[i]->bdev);
37 
38 		blk_unplug(r_queue);
39 	}
40 }
41 
42 static int raid0_congested(void *data, int bits)
43 {
44 	mddev_t *mddev = data;
45 	raid0_conf_t *conf = mddev_to_conf(mddev);
46 	mdk_rdev_t **devlist = conf->strip_zone[0].dev;
47 	int i, ret = 0;
48 
49 	for (i = 0; i < mddev->raid_disks && !ret ; i++) {
50 		struct request_queue *q = bdev_get_queue(devlist[i]->bdev);
51 
52 		ret |= bdi_congested(&q->backing_dev_info, bits);
53 	}
54 	return ret;
55 }
56 
57 
58 static int create_strip_zones (mddev_t *mddev)
59 {
60 	int i, c, j;
61 	sector_t current_offset, curr_zone_offset;
62 	sector_t min_spacing;
63 	raid0_conf_t *conf = mddev_to_conf(mddev);
64 	mdk_rdev_t *smallest, *rdev1, *rdev2, *rdev;
65 	struct list_head *tmp1, *tmp2;
66 	struct strip_zone *zone;
67 	int cnt;
68 	char b[BDEVNAME_SIZE];
69 
70 	/*
71 	 * The number of 'same size groups'
72 	 */
73 	conf->nr_strip_zones = 0;
74 
75 	rdev_for_each(rdev1, tmp1, mddev) {
76 		printk("raid0: looking at %s\n",
77 			bdevname(rdev1->bdev,b));
78 		c = 0;
79 		rdev_for_each(rdev2, tmp2, mddev) {
80 			printk("raid0:   comparing %s(%llu)",
81 			       bdevname(rdev1->bdev,b),
82 			       (unsigned long long)rdev1->size);
83 			printk(" with %s(%llu)\n",
84 			       bdevname(rdev2->bdev,b),
85 			       (unsigned long long)rdev2->size);
86 			if (rdev2 == rdev1) {
87 				printk("raid0:   END\n");
88 				break;
89 			}
90 			if (rdev2->size == rdev1->size)
91 			{
92 				/*
93 				 * Not unique, don't count it as a new
94 				 * group
95 				 */
96 				printk("raid0:   EQUAL\n");
97 				c = 1;
98 				break;
99 			}
100 			printk("raid0:   NOT EQUAL\n");
101 		}
102 		if (!c) {
103 			printk("raid0:   ==> UNIQUE\n");
104 			conf->nr_strip_zones++;
105 			printk("raid0: %d zones\n", conf->nr_strip_zones);
106 		}
107 	}
108 	printk("raid0: FINAL %d zones\n", conf->nr_strip_zones);
109 
110 	conf->strip_zone = kzalloc(sizeof(struct strip_zone)*
111 				conf->nr_strip_zones, GFP_KERNEL);
112 	if (!conf->strip_zone)
113 		return 1;
114 	conf->devlist = kzalloc(sizeof(mdk_rdev_t*)*
115 				conf->nr_strip_zones*mddev->raid_disks,
116 				GFP_KERNEL);
117 	if (!conf->devlist)
118 		return 1;
119 
120 	/* The first zone must contain all devices, so here we check that
121 	 * there is a proper alignment of slots to devices and find them all
122 	 */
123 	zone = &conf->strip_zone[0];
124 	cnt = 0;
125 	smallest = NULL;
126 	zone->dev = conf->devlist;
127 	rdev_for_each(rdev1, tmp1, mddev) {
128 		int j = rdev1->raid_disk;
129 
130 		if (j < 0 || j >= mddev->raid_disks) {
131 			printk("raid0: bad disk number %d - aborting!\n", j);
132 			goto abort;
133 		}
134 		if (zone->dev[j]) {
135 			printk("raid0: multiple devices for %d - aborting!\n",
136 				j);
137 			goto abort;
138 		}
139 		zone->dev[j] = rdev1;
140 
141 		blk_queue_stack_limits(mddev->queue,
142 				       rdev1->bdev->bd_disk->queue);
143 		/* as we don't honour merge_bvec_fn, we must never risk
144 		 * violating it, so limit ->max_sector to one PAGE, as
145 		 * a one page request is never in violation.
146 		 */
147 
148 		if (rdev1->bdev->bd_disk->queue->merge_bvec_fn &&
149 		    mddev->queue->max_sectors > (PAGE_SIZE>>9))
150 			blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
151 
152 		if (!smallest || (rdev1->size <smallest->size))
153 			smallest = rdev1;
154 		cnt++;
155 	}
156 	if (cnt != mddev->raid_disks) {
157 		printk("raid0: too few disks (%d of %d) - aborting!\n",
158 			cnt, mddev->raid_disks);
159 		goto abort;
160 	}
161 	zone->nb_dev = cnt;
162 	zone->size = smallest->size * cnt;
163 	zone->zone_offset = 0;
164 
165 	current_offset = smallest->size;
166 	curr_zone_offset = zone->size;
167 
168 	/* now do the other zones */
169 	for (i = 1; i < conf->nr_strip_zones; i++)
170 	{
171 		zone = conf->strip_zone + i;
172 		zone->dev = conf->strip_zone[i-1].dev + mddev->raid_disks;
173 
174 		printk("raid0: zone %d\n", i);
175 		zone->dev_offset = current_offset;
176 		smallest = NULL;
177 		c = 0;
178 
179 		for (j=0; j<cnt; j++) {
180 			char b[BDEVNAME_SIZE];
181 			rdev = conf->strip_zone[0].dev[j];
182 			printk("raid0: checking %s ...", bdevname(rdev->bdev,b));
183 			if (rdev->size > current_offset)
184 			{
185 				printk(" contained as device %d\n", c);
186 				zone->dev[c] = rdev;
187 				c++;
188 				if (!smallest || (rdev->size <smallest->size)) {
189 					smallest = rdev;
190 					printk("  (%llu) is smallest!.\n",
191 						(unsigned long long)rdev->size);
192 				}
193 			} else
194 				printk(" nope.\n");
195 		}
196 
197 		zone->nb_dev = c;
198 		zone->size = (smallest->size - current_offset) * c;
199 		printk("raid0: zone->nb_dev: %d, size: %llu\n",
200 			zone->nb_dev, (unsigned long long)zone->size);
201 
202 		zone->zone_offset = curr_zone_offset;
203 		curr_zone_offset += zone->size;
204 
205 		current_offset = smallest->size;
206 		printk("raid0: current zone offset: %llu\n",
207 			(unsigned long long)current_offset);
208 	}
209 
210 	/* Now find appropriate hash spacing.
211 	 * We want a number which causes most hash entries to cover
212 	 * at most two strips, but the hash table must be at most
213 	 * 1 PAGE.  We choose the smallest strip, or contiguous collection
214 	 * of strips, that has big enough size.  We never consider the last
215 	 * strip though as it's size has no bearing on the efficacy of the hash
216 	 * table.
217 	 */
218 	conf->hash_spacing = curr_zone_offset;
219 	min_spacing = curr_zone_offset;
220 	sector_div(min_spacing, PAGE_SIZE/sizeof(struct strip_zone*));
221 	for (i=0; i < conf->nr_strip_zones-1; i++) {
222 		sector_t sz = 0;
223 		for (j=i; j<conf->nr_strip_zones-1 &&
224 			     sz < min_spacing ; j++)
225 			sz += conf->strip_zone[j].size;
226 		if (sz >= min_spacing && sz < conf->hash_spacing)
227 			conf->hash_spacing = sz;
228 	}
229 
230 	mddev->queue->unplug_fn = raid0_unplug;
231 
232 	mddev->queue->backing_dev_info.congested_fn = raid0_congested;
233 	mddev->queue->backing_dev_info.congested_data = mddev;
234 
235 	printk("raid0: done.\n");
236 	return 0;
237  abort:
238 	return 1;
239 }
240 
241 /**
242  *	raid0_mergeable_bvec -- tell bio layer if a two requests can be merged
243  *	@q: request queue
244  *	@bio: the buffer head that's been built up so far
245  *	@biovec: the request that could be merged to it.
246  *
247  *	Return amount of bytes we can accept at this offset
248  */
249 static int raid0_mergeable_bvec(struct request_queue *q, struct bio *bio, struct bio_vec *biovec)
250 {
251 	mddev_t *mddev = q->queuedata;
252 	sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
253 	int max;
254 	unsigned int chunk_sectors = mddev->chunk_size >> 9;
255 	unsigned int bio_sectors = bio->bi_size >> 9;
256 
257 	max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
258 	if (max < 0) max = 0; /* bio_add cannot handle a negative return */
259 	if (max <= biovec->bv_len && bio_sectors == 0)
260 		return biovec->bv_len;
261 	else
262 		return max;
263 }
264 
265 static int raid0_run (mddev_t *mddev)
266 {
267 	unsigned  cur=0, i=0, nb_zone;
268 	s64 size;
269 	raid0_conf_t *conf;
270 	mdk_rdev_t *rdev;
271 	struct list_head *tmp;
272 
273 	if (mddev->chunk_size == 0) {
274 		printk(KERN_ERR "md/raid0: non-zero chunk size required.\n");
275 		return -EINVAL;
276 	}
277 	printk(KERN_INFO "%s: setting max_sectors to %d, segment boundary to %d\n",
278 	       mdname(mddev),
279 	       mddev->chunk_size >> 9,
280 	       (mddev->chunk_size>>1)-1);
281 	blk_queue_max_sectors(mddev->queue, mddev->chunk_size >> 9);
282 	blk_queue_segment_boundary(mddev->queue, (mddev->chunk_size>>1) - 1);
283 
284 	conf = kmalloc(sizeof (raid0_conf_t), GFP_KERNEL);
285 	if (!conf)
286 		goto out;
287 	mddev->private = (void *)conf;
288 
289 	conf->strip_zone = NULL;
290 	conf->devlist = NULL;
291 	if (create_strip_zones (mddev))
292 		goto out_free_conf;
293 
294 	/* calculate array device size */
295 	mddev->array_size = 0;
296 	rdev_for_each(rdev, tmp, mddev)
297 		mddev->array_size += rdev->size;
298 
299 	printk("raid0 : md_size is %llu blocks.\n",
300 		(unsigned long long)mddev->array_size);
301 	printk("raid0 : conf->hash_spacing is %llu blocks.\n",
302 		(unsigned long long)conf->hash_spacing);
303 	{
304 		sector_t s = mddev->array_size;
305 		sector_t space = conf->hash_spacing;
306 		int round;
307 		conf->preshift = 0;
308 		if (sizeof(sector_t) > sizeof(u32)) {
309 			/*shift down space and s so that sector_div will work */
310 			while (space > (sector_t) (~(u32)0)) {
311 				s >>= 1;
312 				space >>= 1;
313 				s += 1; /* force round-up */
314 				conf->preshift++;
315 			}
316 		}
317 		round = sector_div(s, (u32)space) ? 1 : 0;
318 		nb_zone = s + round;
319 	}
320 	printk("raid0 : nb_zone is %d.\n", nb_zone);
321 
322 	printk("raid0 : Allocating %Zd bytes for hash.\n",
323 				nb_zone*sizeof(struct strip_zone*));
324 	conf->hash_table = kmalloc (sizeof (struct strip_zone *)*nb_zone, GFP_KERNEL);
325 	if (!conf->hash_table)
326 		goto out_free_conf;
327 	size = conf->strip_zone[cur].size;
328 
329 	conf->hash_table[0] = conf->strip_zone + cur;
330 	for (i=1; i< nb_zone; i++) {
331 		while (size <= conf->hash_spacing) {
332 			cur++;
333 			size += conf->strip_zone[cur].size;
334 		}
335 		size -= conf->hash_spacing;
336 		conf->hash_table[i] = conf->strip_zone + cur;
337 	}
338 	if (conf->preshift) {
339 		conf->hash_spacing >>= conf->preshift;
340 		/* round hash_spacing up so when we divide by it, we
341 		 * err on the side of too-low, which is safest
342 		 */
343 		conf->hash_spacing++;
344 	}
345 
346 	/* calculate the max read-ahead size.
347 	 * For read-ahead of large files to be effective, we need to
348 	 * readahead at least twice a whole stripe. i.e. number of devices
349 	 * multiplied by chunk size times 2.
350 	 * If an individual device has an ra_pages greater than the
351 	 * chunk size, then we will not drive that device as hard as it
352 	 * wants.  We consider this a configuration error: a larger
353 	 * chunksize should be used in that case.
354 	 */
355 	{
356 		int stripe = mddev->raid_disks * mddev->chunk_size / PAGE_SIZE;
357 		if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)
358 			mddev->queue->backing_dev_info.ra_pages = 2* stripe;
359 	}
360 
361 
362 	blk_queue_merge_bvec(mddev->queue, raid0_mergeable_bvec);
363 	return 0;
364 
365 out_free_conf:
366 	kfree(conf->strip_zone);
367 	kfree(conf->devlist);
368 	kfree(conf);
369 	mddev->private = NULL;
370 out:
371 	return -ENOMEM;
372 }
373 
374 static int raid0_stop (mddev_t *mddev)
375 {
376 	raid0_conf_t *conf = mddev_to_conf(mddev);
377 
378 	blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
379 	kfree(conf->hash_table);
380 	conf->hash_table = NULL;
381 	kfree(conf->strip_zone);
382 	conf->strip_zone = NULL;
383 	kfree(conf);
384 	mddev->private = NULL;
385 
386 	return 0;
387 }
388 
389 static int raid0_make_request (struct request_queue *q, struct bio *bio)
390 {
391 	mddev_t *mddev = q->queuedata;
392 	unsigned int sect_in_chunk, chunksize_bits,  chunk_size, chunk_sects;
393 	raid0_conf_t *conf = mddev_to_conf(mddev);
394 	struct strip_zone *zone;
395 	mdk_rdev_t *tmp_dev;
396 	sector_t chunk;
397 	sector_t block, rsect;
398 	const int rw = bio_data_dir(bio);
399 
400 	if (unlikely(bio_barrier(bio))) {
401 		bio_endio(bio, -EOPNOTSUPP);
402 		return 0;
403 	}
404 
405 	disk_stat_inc(mddev->gendisk, ios[rw]);
406 	disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bio));
407 
408 	chunk_size = mddev->chunk_size >> 10;
409 	chunk_sects = mddev->chunk_size >> 9;
410 	chunksize_bits = ffz(~chunk_size);
411 	block = bio->bi_sector >> 1;
412 
413 
414 	if (unlikely(chunk_sects < (bio->bi_sector & (chunk_sects - 1)) + (bio->bi_size >> 9))) {
415 		struct bio_pair *bp;
416 		/* Sanity check -- queue functions should prevent this happening */
417 		if (bio->bi_vcnt != 1 ||
418 		    bio->bi_idx != 0)
419 			goto bad_map;
420 		/* This is a one page bio that upper layers
421 		 * refuse to split for us, so we need to split it.
422 		 */
423 		bp = bio_split(bio, bio_split_pool, chunk_sects - (bio->bi_sector & (chunk_sects - 1)) );
424 		if (raid0_make_request(q, &bp->bio1))
425 			generic_make_request(&bp->bio1);
426 		if (raid0_make_request(q, &bp->bio2))
427 			generic_make_request(&bp->bio2);
428 
429 		bio_pair_release(bp);
430 		return 0;
431 	}
432 
433 
434 	{
435 		sector_t x = block >> conf->preshift;
436 		sector_div(x, (u32)conf->hash_spacing);
437 		zone = conf->hash_table[x];
438 	}
439 
440 	while (block >= (zone->zone_offset + zone->size))
441 		zone++;
442 
443 	sect_in_chunk = bio->bi_sector & ((chunk_size<<1) -1);
444 
445 
446 	{
447 		sector_t x =  (block - zone->zone_offset) >> chunksize_bits;
448 
449 		sector_div(x, zone->nb_dev);
450 		chunk = x;
451 
452 		x = block >> chunksize_bits;
453 		tmp_dev = zone->dev[sector_div(x, zone->nb_dev)];
454 	}
455 	rsect = (((chunk << chunksize_bits) + zone->dev_offset)<<1)
456 		+ sect_in_chunk;
457 
458 	bio->bi_bdev = tmp_dev->bdev;
459 	bio->bi_sector = rsect + tmp_dev->data_offset;
460 
461 	/*
462 	 * Let the main block layer submit the IO and resolve recursion:
463 	 */
464 	return 1;
465 
466 bad_map:
467 	printk("raid0_make_request bug: can't convert block across chunks"
468 		" or bigger than %dk %llu %d\n", chunk_size,
469 		(unsigned long long)bio->bi_sector, bio->bi_size >> 10);
470 
471 	bio_io_error(bio);
472 	return 0;
473 }
474 
475 static void raid0_status (struct seq_file *seq, mddev_t *mddev)
476 {
477 #undef MD_DEBUG
478 #ifdef MD_DEBUG
479 	int j, k, h;
480 	char b[BDEVNAME_SIZE];
481 	raid0_conf_t *conf = mddev_to_conf(mddev);
482 
483 	h = 0;
484 	for (j = 0; j < conf->nr_strip_zones; j++) {
485 		seq_printf(seq, "      z%d", j);
486 		if (conf->hash_table[h] == conf->strip_zone+j)
487 			seq_printf(seq, "(h%d)", h++);
488 		seq_printf(seq, "=[");
489 		for (k = 0; k < conf->strip_zone[j].nb_dev; k++)
490 			seq_printf(seq, "%s/", bdevname(
491 				conf->strip_zone[j].dev[k]->bdev,b));
492 
493 		seq_printf(seq, "] zo=%d do=%d s=%d\n",
494 				conf->strip_zone[j].zone_offset,
495 				conf->strip_zone[j].dev_offset,
496 				conf->strip_zone[j].size);
497 	}
498 #endif
499 	seq_printf(seq, " %dk chunks", mddev->chunk_size/1024);
500 	return;
501 }
502 
503 static struct mdk_personality raid0_personality=
504 {
505 	.name		= "raid0",
506 	.level		= 0,
507 	.owner		= THIS_MODULE,
508 	.make_request	= raid0_make_request,
509 	.run		= raid0_run,
510 	.stop		= raid0_stop,
511 	.status		= raid0_status,
512 };
513 
514 static int __init raid0_init (void)
515 {
516 	return register_md_personality (&raid0_personality);
517 }
518 
519 static void raid0_exit (void)
520 {
521 	unregister_md_personality (&raid0_personality);
522 }
523 
524 module_init(raid0_init);
525 module_exit(raid0_exit);
526 MODULE_LICENSE("GPL");
527 MODULE_ALIAS("md-personality-2"); /* RAID0 */
528 MODULE_ALIAS("md-raid0");
529 MODULE_ALIAS("md-level-0");
530