w1: add missing Kconfig/Makefile entries for DS2431 slave driver
[linux-2.6] / drivers / md / raid0.c
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/raid/raid0.h>
22
23 static void raid0_unplug(struct request_queue *q)
24 {
25         mddev_t *mddev = q->queuedata;
26         raid0_conf_t *conf = mddev_to_conf(mddev);
27         mdk_rdev_t **devlist = conf->strip_zone[0].dev;
28         int i;
29
30         for (i=0; i<mddev->raid_disks; i++) {
31                 struct request_queue *r_queue = bdev_get_queue(devlist[i]->bdev);
32
33                 blk_unplug(r_queue);
34         }
35 }
36
37 static int raid0_congested(void *data, int bits)
38 {
39         mddev_t *mddev = data;
40         raid0_conf_t *conf = mddev_to_conf(mddev);
41         mdk_rdev_t **devlist = conf->strip_zone[0].dev;
42         int i, ret = 0;
43
44         for (i = 0; i < mddev->raid_disks && !ret ; i++) {
45                 struct request_queue *q = bdev_get_queue(devlist[i]->bdev);
46
47                 ret |= bdi_congested(&q->backing_dev_info, bits);
48         }
49         return ret;
50 }
51
52
53 static int create_strip_zones (mddev_t *mddev)
54 {
55         int i, c, j;
56         sector_t current_start, curr_zone_start;
57         sector_t min_spacing;
58         raid0_conf_t *conf = mddev_to_conf(mddev);
59         mdk_rdev_t *smallest, *rdev1, *rdev2, *rdev;
60         struct strip_zone *zone;
61         int cnt;
62         char b[BDEVNAME_SIZE];
63  
64         /*
65          * The number of 'same size groups'
66          */
67         conf->nr_strip_zones = 0;
68  
69         list_for_each_entry(rdev1, &mddev->disks, same_set) {
70                 printk(KERN_INFO "raid0: looking at %s\n",
71                         bdevname(rdev1->bdev,b));
72                 c = 0;
73                 list_for_each_entry(rdev2, &mddev->disks, same_set) {
74                         printk(KERN_INFO "raid0:   comparing %s(%llu)",
75                                bdevname(rdev1->bdev,b),
76                                (unsigned long long)rdev1->size);
77                         printk(KERN_INFO " with %s(%llu)\n",
78                                bdevname(rdev2->bdev,b),
79                                (unsigned long long)rdev2->size);
80                         if (rdev2 == rdev1) {
81                                 printk(KERN_INFO "raid0:   END\n");
82                                 break;
83                         }
84                         if (rdev2->size == rdev1->size)
85                         {
86                                 /*
87                                  * Not unique, don't count it as a new
88                                  * group
89                                  */
90                                 printk(KERN_INFO "raid0:   EQUAL\n");
91                                 c = 1;
92                                 break;
93                         }
94                         printk(KERN_INFO "raid0:   NOT EQUAL\n");
95                 }
96                 if (!c) {
97                         printk(KERN_INFO "raid0:   ==> UNIQUE\n");
98                         conf->nr_strip_zones++;
99                         printk(KERN_INFO "raid0: %d zones\n",
100                                 conf->nr_strip_zones);
101                 }
102         }
103         printk(KERN_INFO "raid0: FINAL %d zones\n", conf->nr_strip_zones);
104
105         conf->strip_zone = kzalloc(sizeof(struct strip_zone)*
106                                 conf->nr_strip_zones, GFP_KERNEL);
107         if (!conf->strip_zone)
108                 return 1;
109         conf->devlist = kzalloc(sizeof(mdk_rdev_t*)*
110                                 conf->nr_strip_zones*mddev->raid_disks,
111                                 GFP_KERNEL);
112         if (!conf->devlist)
113                 return 1;
114
115         /* The first zone must contain all devices, so here we check that
116          * there is a proper alignment of slots to devices and find them all
117          */
118         zone = &conf->strip_zone[0];
119         cnt = 0;
120         smallest = NULL;
121         zone->dev = conf->devlist;
122         list_for_each_entry(rdev1, &mddev->disks, same_set) {
123                 int j = rdev1->raid_disk;
124
125                 if (j < 0 || j >= mddev->raid_disks) {
126                         printk(KERN_ERR "raid0: bad disk number %d - "
127                                 "aborting!\n", j);
128                         goto abort;
129                 }
130                 if (zone->dev[j]) {
131                         printk(KERN_ERR "raid0: multiple devices for %d - "
132                                 "aborting!\n", j);
133                         goto abort;
134                 }
135                 zone->dev[j] = rdev1;
136
137                 blk_queue_stack_limits(mddev->queue,
138                                        rdev1->bdev->bd_disk->queue);
139                 /* as we don't honour merge_bvec_fn, we must never risk
140                  * violating it, so limit ->max_sector to one PAGE, as
141                  * a one page request is never in violation.
142                  */
143
144                 if (rdev1->bdev->bd_disk->queue->merge_bvec_fn &&
145                     mddev->queue->max_sectors > (PAGE_SIZE>>9))
146                         blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
147
148                 if (!smallest || (rdev1->size <smallest->size))
149                         smallest = rdev1;
150                 cnt++;
151         }
152         if (cnt != mddev->raid_disks) {
153                 printk(KERN_ERR "raid0: too few disks (%d of %d) - "
154                         "aborting!\n", cnt, mddev->raid_disks);
155                 goto abort;
156         }
157         zone->nb_dev = cnt;
158         zone->sectors = smallest->size * cnt * 2;
159         zone->zone_start = 0;
160
161         current_start = smallest->size * 2;
162         curr_zone_start = zone->sectors;
163
164         /* now do the other zones */
165         for (i = 1; i < conf->nr_strip_zones; i++)
166         {
167                 zone = conf->strip_zone + i;
168                 zone->dev = conf->strip_zone[i-1].dev + mddev->raid_disks;
169
170                 printk(KERN_INFO "raid0: zone %d\n", i);
171                 zone->dev_start = current_start;
172                 smallest = NULL;
173                 c = 0;
174
175                 for (j=0; j<cnt; j++) {
176                         char b[BDEVNAME_SIZE];
177                         rdev = conf->strip_zone[0].dev[j];
178                         printk(KERN_INFO "raid0: checking %s ...",
179                                 bdevname(rdev->bdev, b));
180                         if (rdev->size > current_start / 2) {
181                                 printk(KERN_INFO " contained as device %d\n",
182                                         c);
183                                 zone->dev[c] = rdev;
184                                 c++;
185                                 if (!smallest || (rdev->size <smallest->size)) {
186                                         smallest = rdev;
187                                         printk(KERN_INFO "  (%llu) is smallest!.\n",
188                                                 (unsigned long long)rdev->size);
189                                 }
190                         } else
191                                 printk(KERN_INFO " nope.\n");
192                 }
193
194                 zone->nb_dev = c;
195                 zone->sectors = (smallest->size * 2 - current_start) * c;
196                 printk(KERN_INFO "raid0: zone->nb_dev: %d, sectors: %llu\n",
197                         zone->nb_dev, (unsigned long long)zone->sectors);
198
199                 zone->zone_start = curr_zone_start;
200                 curr_zone_start += zone->sectors;
201
202                 current_start = smallest->size * 2;
203                 printk(KERN_INFO "raid0: current zone start: %llu\n",
204                         (unsigned long long)current_start);
205         }
206
207         /* Now find appropriate hash spacing.
208          * We want a number which causes most hash entries to cover
209          * at most two strips, but the hash table must be at most
210          * 1 PAGE.  We choose the smallest strip, or contiguous collection
211          * of strips, that has big enough size.  We never consider the last
212          * strip though as it's size has no bearing on the efficacy of the hash
213          * table.
214          */
215         conf->spacing = curr_zone_start;
216         min_spacing = curr_zone_start;
217         sector_div(min_spacing, PAGE_SIZE/sizeof(struct strip_zone*));
218         for (i=0; i < conf->nr_strip_zones-1; i++) {
219                 sector_t s = 0;
220                 for (j = i; j < conf->nr_strip_zones - 1 &&
221                                 s < min_spacing; j++)
222                         s += conf->strip_zone[j].sectors;
223                 if (s >= min_spacing && s < conf->spacing)
224                         conf->spacing = s;
225         }
226
227         mddev->queue->unplug_fn = raid0_unplug;
228
229         mddev->queue->backing_dev_info.congested_fn = raid0_congested;
230         mddev->queue->backing_dev_info.congested_data = mddev;
231
232         printk(KERN_INFO "raid0: done.\n");
233         return 0;
234  abort:
235         return 1;
236 }
237
238 /**
239  *      raid0_mergeable_bvec -- tell bio layer if a two requests can be merged
240  *      @q: request queue
241  *      @bvm: properties of new bio
242  *      @biovec: the request that could be merged to it.
243  *
244  *      Return amount of bytes we can accept at this offset
245  */
246 static int raid0_mergeable_bvec(struct request_queue *q,
247                                 struct bvec_merge_data *bvm,
248                                 struct bio_vec *biovec)
249 {
250         mddev_t *mddev = q->queuedata;
251         sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
252         int max;
253         unsigned int chunk_sectors = mddev->chunk_size >> 9;
254         unsigned int bio_sectors = bvm->bi_size >> 9;
255
256         max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
257         if (max < 0) max = 0; /* bio_add cannot handle a negative return */
258         if (max <= biovec->bv_len && bio_sectors == 0)
259                 return biovec->bv_len;
260         else 
261                 return max;
262 }
263
264 static int raid0_run (mddev_t *mddev)
265 {
266         unsigned  cur=0, i=0, nb_zone;
267         s64 sectors;
268         raid0_conf_t *conf;
269         mdk_rdev_t *rdev;
270
271         if (mddev->chunk_size == 0) {
272                 printk(KERN_ERR "md/raid0: non-zero chunk size required.\n");
273                 return -EINVAL;
274         }
275         printk(KERN_INFO "%s: setting max_sectors to %d, segment boundary to %d\n",
276                mdname(mddev),
277                mddev->chunk_size >> 9,
278                (mddev->chunk_size>>1)-1);
279         blk_queue_max_sectors(mddev->queue, mddev->chunk_size >> 9);
280         blk_queue_segment_boundary(mddev->queue, (mddev->chunk_size>>1) - 1);
281         mddev->queue->queue_lock = &mddev->queue->__queue_lock;
282
283         conf = kmalloc(sizeof (raid0_conf_t), GFP_KERNEL);
284         if (!conf)
285                 goto out;
286         mddev->private = (void *)conf;
287  
288         conf->strip_zone = NULL;
289         conf->devlist = NULL;
290         if (create_strip_zones (mddev)) 
291                 goto out_free_conf;
292
293         /* calculate array device size */
294         mddev->array_sectors = 0;
295         list_for_each_entry(rdev, &mddev->disks, same_set)
296                 mddev->array_sectors += rdev->size * 2;
297
298         printk(KERN_INFO "raid0 : md_size is %llu sectors.\n",
299                 (unsigned long long)mddev->array_sectors);
300         printk(KERN_INFO "raid0 : conf->spacing is %llu sectors.\n",
301                 (unsigned long long)conf->spacing);
302         {
303                 sector_t s = mddev->array_sectors;
304                 sector_t space = conf->spacing;
305                 int round;
306                 conf->sector_shift = 0;
307                 if (sizeof(sector_t) > sizeof(u32)) {
308                         /*shift down space and s so that sector_div will work */
309                         while (space > (sector_t) (~(u32)0)) {
310                                 s >>= 1;
311                                 space >>= 1;
312                                 s += 1; /* force round-up */
313                                 conf->sector_shift++;
314                         }
315                 }
316                 round = sector_div(s, (u32)space) ? 1 : 0;
317                 nb_zone = s + round;
318         }
319         printk(KERN_INFO "raid0 : nb_zone is %d.\n", nb_zone);
320
321         printk(KERN_INFO "raid0 : Allocating %zu bytes for hash.\n",
322                                 nb_zone*sizeof(struct strip_zone*));
323         conf->hash_table = kmalloc (sizeof (struct strip_zone *)*nb_zone, GFP_KERNEL);
324         if (!conf->hash_table)
325                 goto out_free_conf;
326         sectors = conf->strip_zone[cur].sectors;
327
328         conf->hash_table[0] = conf->strip_zone + cur;
329         for (i=1; i< nb_zone; i++) {
330                 while (sectors <= conf->spacing) {
331                         cur++;
332                         sectors += conf->strip_zone[cur].sectors;
333                 }
334                 sectors -= conf->spacing;
335                 conf->hash_table[i] = conf->strip_zone + cur;
336         }
337         if (conf->sector_shift) {
338                 conf->spacing >>= conf->sector_shift;
339                 /* round spacing up so when we divide by it, we
340                  * err on the side of too-low, which is safest
341                  */
342                 conf->spacing++;
343         }
344
345         /* calculate the max read-ahead size.
346          * For read-ahead of large files to be effective, we need to
347          * readahead at least twice a whole stripe. i.e. number of devices
348          * multiplied by chunk size times 2.
349          * If an individual device has an ra_pages greater than the
350          * chunk size, then we will not drive that device as hard as it
351          * wants.  We consider this a configuration error: a larger
352          * chunksize should be used in that case.
353          */
354         {
355                 int stripe = mddev->raid_disks * mddev->chunk_size / PAGE_SIZE;
356                 if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)
357                         mddev->queue->backing_dev_info.ra_pages = 2* stripe;
358         }
359
360
361         blk_queue_merge_bvec(mddev->queue, raid0_mergeable_bvec);
362         return 0;
363
364 out_free_conf:
365         kfree(conf->strip_zone);
366         kfree(conf->devlist);
367         kfree(conf);
368         mddev->private = NULL;
369 out:
370         return -ENOMEM;
371 }
372
373 static int raid0_stop (mddev_t *mddev)
374 {
375         raid0_conf_t *conf = mddev_to_conf(mddev);
376
377         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
378         kfree(conf->hash_table);
379         conf->hash_table = NULL;
380         kfree(conf->strip_zone);
381         conf->strip_zone = NULL;
382         kfree(conf);
383         mddev->private = NULL;
384
385         return 0;
386 }
387
388 static int raid0_make_request (struct request_queue *q, struct bio *bio)
389 {
390         mddev_t *mddev = q->queuedata;
391         unsigned int sect_in_chunk, chunksect_bits, chunk_sects;
392         raid0_conf_t *conf = mddev_to_conf(mddev);
393         struct strip_zone *zone;
394         mdk_rdev_t *tmp_dev;
395         sector_t chunk;
396         sector_t sector, rsect;
397         const int rw = bio_data_dir(bio);
398         int cpu;
399
400         if (unlikely(bio_barrier(bio))) {
401                 bio_endio(bio, -EOPNOTSUPP);
402                 return 0;
403         }
404
405         cpu = part_stat_lock();
406         part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]);
407         part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw],
408                       bio_sectors(bio));
409         part_stat_unlock();
410
411         chunk_sects = mddev->chunk_size >> 9;
412         chunksect_bits = ffz(~chunk_sects);
413         sector = bio->bi_sector;
414
415         if (unlikely(chunk_sects < (bio->bi_sector & (chunk_sects - 1)) + (bio->bi_size >> 9))) {
416                 struct bio_pair *bp;
417                 /* Sanity check -- queue functions should prevent this happening */
418                 if (bio->bi_vcnt != 1 ||
419                     bio->bi_idx != 0)
420                         goto bad_map;
421                 /* This is a one page bio that upper layers
422                  * refuse to split for us, so we need to split it.
423                  */
424                 bp = bio_split(bio, chunk_sects - (bio->bi_sector & (chunk_sects - 1)));
425                 if (raid0_make_request(q, &bp->bio1))
426                         generic_make_request(&bp->bio1);
427                 if (raid0_make_request(q, &bp->bio2))
428                         generic_make_request(&bp->bio2);
429
430                 bio_pair_release(bp);
431                 return 0;
432         }
433  
434
435         {
436                 sector_t x = sector >> conf->sector_shift;
437                 sector_div(x, (u32)conf->spacing);
438                 zone = conf->hash_table[x];
439         }
440
441         while (sector >= zone->zone_start + zone->sectors)
442                 zone++;
443
444         sect_in_chunk = bio->bi_sector & (chunk_sects - 1);
445
446
447         {
448                 sector_t x = (sector - zone->zone_start) >> chunksect_bits;
449
450                 sector_div(x, zone->nb_dev);
451                 chunk = x;
452
453                 x = sector >> chunksect_bits;
454                 tmp_dev = zone->dev[sector_div(x, zone->nb_dev)];
455         }
456         rsect = (chunk << chunksect_bits) + zone->dev_start + 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_sects / 2,
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, "] zs=%d ds=%d s=%d\n",
494                                 conf->strip_zone[j].zone_start,
495                                 conf->strip_zone[j].dev_start,
496                                 conf->strip_zone[j].sectors);
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");