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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/blkdev.h>
  22 #include <linux/seq_file.h>
  23 #include "md.h"
  24 #include "raid0.h"
  25
  26 static void raid0_unplug(struct request_queue *q)
  27 {
  28         mddev_t *mddev = q->queuedata;
  29         raid0_conf_t *conf = mddev_to_conf(mddev);
  30         mdk_rdev_t **devlist = conf->strip_zone[0].dev;
  31         int i;
  32
  33         for (i=0; i<mddev->raid_disks; i++) {
  34                 struct request_queue *r_queue = bdev_get_queue(devlist[i]->bdev);
  35
  36                 blk_unplug(r_queue);
  37         }
  38 }
  39
  40 static int raid0_congested(void *data, int bits)
  41 {
  42         mddev_t *mddev = data;
  43         raid0_conf_t *conf = mddev_to_conf(mddev);
  44         mdk_rdev_t **devlist = conf->strip_zone[0].dev;
  45         int i, ret = 0;
  46
  47         for (i = 0; i < mddev->raid_disks && !ret ; i++) {
  48                 struct request_queue *q = bdev_get_queue(devlist[i]->bdev);
  49
  50                 ret |= bdi_congested(&q->backing_dev_info, bits);
  51         }
  52         return ret;
  53 }
  54
  55 static int create_strip_zones (mddev_t *mddev)
  56 {
  57         int i, c, j;
  58         sector_t curr_zone_end;
  59         raid0_conf_t *conf = mddev_to_conf(mddev);
  60         mdk_rdev_t *smallest, *rdev1, *rdev2, *rdev;
  61         struct strip_zone *zone;
  62         int cnt;
  63         char b[BDEVNAME_SIZE];
  64
  65         /*
  66          * The number of 'same size groups'
  67          */
  68         conf->nr_strip_zones = 0;
  69
  70         list_for_each_entry(rdev1, &mddev->disks, same_set) {
  71                 printk(KERN_INFO "raid0: looking at %s\n",
  72                         bdevname(rdev1->bdev,b));
  73                 c = 0;
  74                 list_for_each_entry(rdev2, &mddev->disks, same_set) {
  75                         printk(KERN_INFO "raid0:   comparing %s(%llu)",
  76                                bdevname(rdev1->bdev,b),
  77                                (unsigned long long)rdev1->sectors);
  78                         printk(KERN_INFO " with %s(%llu)\n",
  79                                bdevname(rdev2->bdev,b),
  80                                (unsigned long long)rdev2->sectors);
  81                         if (rdev2 == rdev1) {
  82                                 printk(KERN_INFO "raid0:   END\n");
  83                                 break;
  84                         }
  85                         if (rdev2->sectors == rdev1->sectors) {
  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 -ENOMEM;
 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 -ENOMEM;
 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                     queue_max_sectors(mddev->queue) > (PAGE_SIZE>>9))
 146                         blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
 147
 148                 if (!smallest || (rdev1->sectors < smallest->sectors))
 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->sectors * cnt;
 159         zone->zone_end = zone->sectors;
 160
 161         curr_zone_end = zone->sectors;
 162
 163         /* now do the other zones */
 164         for (i = 1; i < conf->nr_strip_zones; i++)
 165         {
 166                 zone = conf->strip_zone + i;
 167                 zone->dev = conf->strip_zone[i-1].dev + mddev->raid_disks;
 168
 169                 printk(KERN_INFO "raid0: zone %d\n", i);
 170                 zone->dev_start = smallest->sectors;
 171                 smallest = NULL;
 172                 c = 0;
 173
 174                 for (j=0; j<cnt; j++) {
 175                         char b[BDEVNAME_SIZE];
 176                         rdev = conf->strip_zone[0].dev[j];
 177                         printk(KERN_INFO "raid0: checking %s ...",
 178                                 bdevname(rdev->bdev, b));
 179                         if (rdev->sectors <= zone->dev_start) {
 180                                 printk(KERN_INFO " nope.\n");
 181                                 continue;
 182                         }
 183                         printk(KERN_INFO " contained as device %d\n", c);
 184                         zone->dev[c] = rdev;
 185                         c++;
 186                         if (!smallest || rdev->sectors < smallest->sectors) {
 187                                 smallest = rdev;
 188                                 printk(KERN_INFO "  (%llu) is smallest!.\n",
 189                                         (unsigned long long)rdev->sectors);
 190                         }
 191                 }
 192
 193                 zone->nb_dev = c;
 194                 zone->sectors = (smallest->sectors - zone->dev_start) * c;
 195                 printk(KERN_INFO "raid0: zone->nb_dev: %d, sectors: %llu\n",
 196                         zone->nb_dev, (unsigned long long)zone->sectors);
 197
 198                 curr_zone_end += zone->sectors;
 199                 zone->zone_end = curr_zone_end;
 200
 201                 printk(KERN_INFO "raid0: current zone start: %llu\n",
 202                         (unsigned long long)smallest->sectors);
 203         }
 204         mddev->queue->unplug_fn = raid0_unplug;
 205         mddev->queue->backing_dev_info.congested_fn = raid0_congested;
 206         mddev->queue->backing_dev_info.congested_data = mddev;
 207
 208         printk(KERN_INFO "raid0: done.\n");
 209         return 0;
 210 abort:
 211         return -EINVAL;
 212 }
 213
 214 /**
 215  *      raid0_mergeable_bvec -- tell bio layer if a two requests can be merged
 216  *      @q: request queue
 217  *      @bvm: properties of new bio
 218  *      @biovec: the request that could be merged to it.
 219  *
 220  *      Return amount of bytes we can accept at this offset
 221  */
 222 static int raid0_mergeable_bvec(struct request_queue *q,
 223                                 struct bvec_merge_data *bvm,
 224                                 struct bio_vec *biovec)
 225 {
 226         mddev_t *mddev = q->queuedata;
 227         sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
 228         int max;
 229         unsigned int chunk_sectors = mddev->chunk_size >> 9;
 230         unsigned int bio_sectors = bvm->bi_size >> 9;
 231
 232         max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
 233         if (max < 0) max = 0; /* bio_add cannot handle a negative return */
 234         if (max <= biovec->bv_len && bio_sectors == 0)
 235                 return biovec->bv_len;
 236         else
 237                 return max;
 238 }
 239
 240 static sector_t raid0_size(mddev_t *mddev, sector_t sectors, int raid_disks)
 241 {
 242         sector_t array_sectors = 0;
 243         mdk_rdev_t *rdev;
 244
 245         WARN_ONCE(sectors || raid_disks,
 246                   "%s does not support generic reshape\n", __func__);
 247
 248         list_for_each_entry(rdev, &mddev->disks, same_set)
 249                 array_sectors += rdev->sectors;
 250
 251         return array_sectors;
 252 }
 253
 254 static int raid0_run(mddev_t *mddev)
 255 {
 256         raid0_conf_t *conf;
 257         int ret;
 258
 259         if (mddev->chunk_size == 0) {
 260                 printk(KERN_ERR "md/raid0: non-zero chunk size required.\n");
 261                 return -EINVAL;
 262         }
 263         printk(KERN_INFO "%s: setting max_sectors to %d, segment boundary to %d\n",
 264                mdname(mddev),
 265                mddev->chunk_size >> 9,
 266                (mddev->chunk_size>>1)-1);
 267         blk_queue_max_sectors(mddev->queue, mddev->chunk_size >> 9);
 268         blk_queue_segment_boundary(mddev->queue, (mddev->chunk_size>>1) - 1);
 269         mddev->queue->queue_lock = &mddev->queue->__queue_lock;
 270
 271         conf = kmalloc(sizeof (raid0_conf_t), GFP_KERNEL);
 272         if (!conf)
 273                 return -ENOMEM;
 274         mddev->private = (void *)conf;
 275
 276         conf->strip_zone = NULL;
 277         conf->devlist = NULL;
 278         ret = create_strip_zones(mddev);
 279         if (ret < 0)
 280                 goto out_free_conf;
 281
 282         /* calculate array device size */
 283         md_set_array_sectors(mddev, raid0_size(mddev, 0, 0));
 284
 285         printk(KERN_INFO "raid0 : md_size is %llu sectors.\n",
 286                 (unsigned long long)mddev->array_sectors);
 287         /* calculate the max read-ahead size.
 288          * For read-ahead of large files to be effective, we need to
 289          * readahead at least twice a whole stripe. i.e. number of devices
 290          * multiplied by chunk size times 2.
 291          * If an individual device has an ra_pages greater than the
 292          * chunk size, then we will not drive that device as hard as it
 293          * wants.  We consider this a configuration error: a larger
 294          * chunksize should be used in that case.
 295          */
 296         {
 297                 int stripe = mddev->raid_disks * mddev->chunk_size / PAGE_SIZE;
 298                 if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)
 299                         mddev->queue->backing_dev_info.ra_pages = 2* stripe;
 300         }
 301
 302
 303         blk_queue_merge_bvec(mddev->queue, raid0_mergeable_bvec);
 304         return 0;
 305
 306 out_free_conf:
 307         kfree(conf->strip_zone);
 308         kfree(conf->devlist);
 309         kfree(conf);
 310         mddev->private = NULL;
 311         return ret;
 312 }
 313
 314 static int raid0_stop (mddev_t *mddev)
 315 {
 316         raid0_conf_t *conf = mddev_to_conf(mddev);
 317
 318         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
 319         kfree(conf->strip_zone);
 320         conf->strip_zone = NULL;
 321         kfree(conf);
 322         mddev->private = NULL;
 323
 324         return 0;
 325 }
 326
 327 /* Find the zone which holds a particular offset */
 328 static struct strip_zone *find_zone(struct raid0_private_data *conf,
 329                 sector_t sector)
 330 {
 331         int i;
 332         struct strip_zone *z = conf->strip_zone;
 333
 334         for (i = 0; i < conf->nr_strip_zones; i++)
 335                 if (sector < z[i].zone_end)
 336                         return z + i;
 337         BUG();
 338 }
 339
 340 static int raid0_make_request (struct request_queue *q, struct bio *bio)
 341 {
 342         mddev_t *mddev = q->queuedata;
 343         unsigned int sect_in_chunk, chunksect_bits, chunk_sects;
 344         raid0_conf_t *conf = mddev_to_conf(mddev);
 345         struct strip_zone *zone;
 346         mdk_rdev_t *tmp_dev;
 347         sector_t chunk;
 348         sector_t sector, rsect;
 349         const int rw = bio_data_dir(bio);
 350         int cpu;
 351
 352         if (unlikely(bio_barrier(bio))) {
 353                 bio_endio(bio, -EOPNOTSUPP);
 354                 return 0;
 355         }
 356
 357         cpu = part_stat_lock();
 358         part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]);
 359         part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw],
 360                       bio_sectors(bio));
 361         part_stat_unlock();
 362
 363         chunk_sects = mddev->chunk_size >> 9;
 364         chunksect_bits = ffz(~chunk_sects);
 365         sector = bio->bi_sector;
 366
 367         if (unlikely(chunk_sects < (bio->bi_sector & (chunk_sects - 1)) + (bio->bi_size >> 9))) {
 368                 struct bio_pair *bp;
 369                 /* Sanity check -- queue functions should prevent this happening */
 370                 if (bio->bi_vcnt != 1 ||
 371                     bio->bi_idx != 0)
 372                         goto bad_map;
 373                 /* This is a one page bio that upper layers
 374                  * refuse to split for us, so we need to split it.
 375                  */
 376                 bp = bio_split(bio, chunk_sects - (bio->bi_sector & (chunk_sects - 1)));
 377                 if (raid0_make_request(q, &bp->bio1))
 378                         generic_make_request(&bp->bio1);
 379                 if (raid0_make_request(q, &bp->bio2))
 380                         generic_make_request(&bp->bio2);
 381
 382                 bio_pair_release(bp);
 383                 return 0;
 384         }
 385         zone = find_zone(conf, sector);
 386         sect_in_chunk = bio->bi_sector & (chunk_sects - 1);
 387         {
 388                 sector_t x = (zone->sectors + sector - zone->zone_end)
 389                                 >> chunksect_bits;
 390
 391                 sector_div(x, zone->nb_dev);
 392                 chunk = x;
 393
 394                 x = sector >> chunksect_bits;
 395                 tmp_dev = zone->dev[sector_div(x, zone->nb_dev)];
 396         }
 397         rsect = (chunk << chunksect_bits) + zone->dev_start + sect_in_chunk;
 398
 399         bio->bi_bdev = tmp_dev->bdev;
 400         bio->bi_sector = rsect + tmp_dev->data_offset;
 401
 402         /*
 403          * Let the main block layer submit the IO and resolve recursion:
 404          */
 405         return 1;
 406
 407 bad_map:
 408         printk("raid0_make_request bug: can't convert block across chunks"
 409                 " or bigger than %dk %llu %d\n", chunk_sects / 2,
 410                 (unsigned long long)bio->bi_sector, bio->bi_size >> 10);
 411
 412         bio_io_error(bio);
 413         return 0;
 414 }
 415
 416 static void raid0_status (struct seq_file *seq, mddev_t *mddev)
 417 {
 418 #undef MD_DEBUG
 419 #ifdef MD_DEBUG
 420         int j, k, h;
 421         char b[BDEVNAME_SIZE];
 422         raid0_conf_t *conf = mddev_to_conf(mddev);
 423
 424         h = 0;
 425         for (j = 0; j < conf->nr_strip_zones; j++) {
 426                 seq_printf(seq, "      z%d", j);
 427                 seq_printf(seq, "=[");
 428                 for (k = 0; k < conf->strip_zone[j].nb_dev; k++)
 429                         seq_printf(seq, "%s/", bdevname(
 430                                 conf->strip_zone[j].dev[k]->bdev,b));
 431
 432                 seq_printf(seq, "] ze=%d ds=%d s=%d\n",
 433                                 conf->strip_zone[j].zone_end,
 434                                 conf->strip_zone[j].dev_start,
 435                                 conf->strip_zone[j].sectors);
 436         }
 437 #endif
 438         seq_printf(seq, " %dk chunks", mddev->chunk_size/1024);
 439         return;
 440 }
 441
 442 static struct mdk_personality raid0_personality=
 443 {
 444         .name           = "raid0",
 445         .level          = 0,
 446         .owner          = THIS_MODULE,
 447         .make_request   = raid0_make_request,
 448         .run            = raid0_run,
 449         .stop           = raid0_stop,
 450         .status         = raid0_status,
 451         .size           = raid0_size,
 452 };
 453
 454 static int __init raid0_init (void)
 455 {
 456         return register_md_personality (&raid0_personality);
 457 }
 458
 459 static void raid0_exit (void)
 460 {
 461         unregister_md_personality (&raid0_personality);
 462 }
 463
 464 module_init(raid0_init);
 465 module_exit(raid0_exit);
 466 MODULE_LICENSE("GPL");
 467 MODULE_ALIAS("md-personality-2"); /* RAID0 */
 468 MODULE_ALIAS("md-raid0");
 469 MODULE_ALIAS("md-level-0");