Merge git://git.kernel.org/pub/scm/linux/kernel/git/sam/kbuild-fixes
[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/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->private;
30         mdk_rdev_t **devlist = conf->devlist;
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->private;
44         mdk_rdev_t **devlist = conf->devlist;
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 /*
56  * inform the user of the raid configuration
57 */
58 static void dump_zones(mddev_t *mddev)
59 {
60         int j, k, h;
61         sector_t zone_size = 0;
62         sector_t zone_start = 0;
63         char b[BDEVNAME_SIZE];
64         raid0_conf_t *conf = mddev->private;
65         printk(KERN_INFO "******* %s configuration *********\n",
66                 mdname(mddev));
67         h = 0;
68         for (j = 0; j < conf->nr_strip_zones; j++) {
69                 printk(KERN_INFO "zone%d=[", j);
70                 for (k = 0; k < conf->strip_zone[j].nb_dev; k++)
71                         printk("%s/",
72                         bdevname(conf->devlist[j*mddev->raid_disks
73                                                 + k]->bdev, b));
74                 printk("]\n");
75
76                 zone_size  = conf->strip_zone[j].zone_end - zone_start;
77                 printk(KERN_INFO "        zone offset=%llukb "
78                                 "device offset=%llukb size=%llukb\n",
79                         (unsigned long long)zone_start>>1,
80                         (unsigned long long)conf->strip_zone[j].dev_start>>1,
81                         (unsigned long long)zone_size>>1);
82                 zone_start = conf->strip_zone[j].zone_end;
83         }
84         printk(KERN_INFO "**********************************\n\n");
85 }
86
87 static int create_strip_zones(mddev_t *mddev)
88 {
89         int i, c, j, err;
90         sector_t curr_zone_end, sectors;
91         mdk_rdev_t *smallest, *rdev1, *rdev2, *rdev, **dev;
92         struct strip_zone *zone;
93         int cnt;
94         char b[BDEVNAME_SIZE];
95         raid0_conf_t *conf = kzalloc(sizeof(*conf), GFP_KERNEL);
96
97         if (!conf)
98                 return -ENOMEM;
99         list_for_each_entry(rdev1, &mddev->disks, same_set) {
100                 printk(KERN_INFO "raid0: looking at %s\n",
101                         bdevname(rdev1->bdev,b));
102                 c = 0;
103
104                 /* round size to chunk_size */
105                 sectors = rdev1->sectors;
106                 sector_div(sectors, mddev->chunk_sectors);
107                 rdev1->sectors = sectors * mddev->chunk_sectors;
108
109                 list_for_each_entry(rdev2, &mddev->disks, same_set) {
110                         printk(KERN_INFO "raid0:   comparing %s(%llu)",
111                                bdevname(rdev1->bdev,b),
112                                (unsigned long long)rdev1->sectors);
113                         printk(KERN_INFO " with %s(%llu)\n",
114                                bdevname(rdev2->bdev,b),
115                                (unsigned long long)rdev2->sectors);
116                         if (rdev2 == rdev1) {
117                                 printk(KERN_INFO "raid0:   END\n");
118                                 break;
119                         }
120                         if (rdev2->sectors == rdev1->sectors) {
121                                 /*
122                                  * Not unique, don't count it as a new
123                                  * group
124                                  */
125                                 printk(KERN_INFO "raid0:   EQUAL\n");
126                                 c = 1;
127                                 break;
128                         }
129                         printk(KERN_INFO "raid0:   NOT EQUAL\n");
130                 }
131                 if (!c) {
132                         printk(KERN_INFO "raid0:   ==> UNIQUE\n");
133                         conf->nr_strip_zones++;
134                         printk(KERN_INFO "raid0: %d zones\n",
135                                 conf->nr_strip_zones);
136                 }
137         }
138         printk(KERN_INFO "raid0: FINAL %d zones\n", conf->nr_strip_zones);
139         err = -ENOMEM;
140         conf->strip_zone = kzalloc(sizeof(struct strip_zone)*
141                                 conf->nr_strip_zones, GFP_KERNEL);
142         if (!conf->strip_zone)
143                 goto abort;
144         conf->devlist = kzalloc(sizeof(mdk_rdev_t*)*
145                                 conf->nr_strip_zones*mddev->raid_disks,
146                                 GFP_KERNEL);
147         if (!conf->devlist)
148                 goto abort;
149
150         /* The first zone must contain all devices, so here we check that
151          * there is a proper alignment of slots to devices and find them all
152          */
153         zone = &conf->strip_zone[0];
154         cnt = 0;
155         smallest = NULL;
156         dev = conf->devlist;
157         err = -EINVAL;
158         list_for_each_entry(rdev1, &mddev->disks, same_set) {
159                 int j = rdev1->raid_disk;
160
161                 if (j < 0 || j >= mddev->raid_disks) {
162                         printk(KERN_ERR "raid0: bad disk number %d - "
163                                 "aborting!\n", j);
164                         goto abort;
165                 }
166                 if (dev[j]) {
167                         printk(KERN_ERR "raid0: multiple devices for %d - "
168                                 "aborting!\n", j);
169                         goto abort;
170                 }
171                 dev[j] = rdev1;
172
173                 blk_queue_stack_limits(mddev->queue,
174                                        rdev1->bdev->bd_disk->queue);
175                 /* as we don't honour merge_bvec_fn, we must never risk
176                  * violating it, so limit ->max_sector to one PAGE, as
177                  * a one page request is never in violation.
178                  */
179
180                 if (rdev1->bdev->bd_disk->queue->merge_bvec_fn &&
181                     queue_max_sectors(mddev->queue) > (PAGE_SIZE>>9))
182                         blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
183
184                 if (!smallest || (rdev1->sectors < smallest->sectors))
185                         smallest = rdev1;
186                 cnt++;
187         }
188         if (cnt != mddev->raid_disks) {
189                 printk(KERN_ERR "raid0: too few disks (%d of %d) - "
190                         "aborting!\n", cnt, mddev->raid_disks);
191                 goto abort;
192         }
193         zone->nb_dev = cnt;
194         zone->zone_end = smallest->sectors * cnt;
195
196         curr_zone_end = zone->zone_end;
197
198         /* now do the other zones */
199         for (i = 1; i < conf->nr_strip_zones; i++)
200         {
201                 zone = conf->strip_zone + i;
202                 dev = conf->devlist + i * mddev->raid_disks;
203
204                 printk(KERN_INFO "raid0: zone %d\n", i);
205                 zone->dev_start = smallest->sectors;
206                 smallest = NULL;
207                 c = 0;
208
209                 for (j=0; j<cnt; j++) {
210                         char b[BDEVNAME_SIZE];
211                         rdev = conf->devlist[j];
212                         printk(KERN_INFO "raid0: checking %s ...",
213                                 bdevname(rdev->bdev, b));
214                         if (rdev->sectors <= zone->dev_start) {
215                                 printk(KERN_INFO " nope.\n");
216                                 continue;
217                         }
218                         printk(KERN_INFO " contained as device %d\n", c);
219                         dev[c] = rdev;
220                         c++;
221                         if (!smallest || rdev->sectors < smallest->sectors) {
222                                 smallest = rdev;
223                                 printk(KERN_INFO "  (%llu) is smallest!.\n",
224                                         (unsigned long long)rdev->sectors);
225                         }
226                 }
227
228                 zone->nb_dev = c;
229                 sectors = (smallest->sectors - zone->dev_start) * c;
230                 printk(KERN_INFO "raid0: zone->nb_dev: %d, sectors: %llu\n",
231                         zone->nb_dev, (unsigned long long)sectors);
232
233                 curr_zone_end += sectors;
234                 zone->zone_end = curr_zone_end;
235
236                 printk(KERN_INFO "raid0: current zone start: %llu\n",
237                         (unsigned long long)smallest->sectors);
238         }
239         mddev->queue->unplug_fn = raid0_unplug;
240         mddev->queue->backing_dev_info.congested_fn = raid0_congested;
241         mddev->queue->backing_dev_info.congested_data = mddev;
242
243         /*
244          * now since we have the hard sector sizes, we can make sure
245          * chunk size is a multiple of that sector size
246          */
247         if ((mddev->chunk_sectors << 9) % queue_logical_block_size(mddev->queue)) {
248                 printk(KERN_ERR "%s chunk_size of %d not valid\n",
249                        mdname(mddev),
250                        mddev->chunk_sectors << 9);
251                 goto abort;
252         }
253         printk(KERN_INFO "raid0: done.\n");
254         mddev->private = conf;
255         return 0;
256 abort:
257         kfree(conf->strip_zone);
258         kfree(conf->devlist);
259         kfree(conf);
260         mddev->private = NULL;
261         return err;
262 }
263
264 /**
265  *      raid0_mergeable_bvec -- tell bio layer if a two requests can be merged
266  *      @q: request queue
267  *      @bvm: properties of new bio
268  *      @biovec: the request that could be merged to it.
269  *
270  *      Return amount of bytes we can accept at this offset
271  */
272 static int raid0_mergeable_bvec(struct request_queue *q,
273                                 struct bvec_merge_data *bvm,
274                                 struct bio_vec *biovec)
275 {
276         mddev_t *mddev = q->queuedata;
277         sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
278         int max;
279         unsigned int chunk_sectors = mddev->chunk_sectors;
280         unsigned int bio_sectors = bvm->bi_size >> 9;
281
282         if (is_power_of_2(chunk_sectors))
283                 max =  (chunk_sectors - ((sector & (chunk_sectors-1))
284                                                 + bio_sectors)) << 9;
285         else
286                 max =  (chunk_sectors - (sector_div(sector, chunk_sectors)
287                                                 + bio_sectors)) << 9;
288         if (max < 0) max = 0; /* bio_add cannot handle a negative return */
289         if (max <= biovec->bv_len && bio_sectors == 0)
290                 return biovec->bv_len;
291         else 
292                 return max;
293 }
294
295 static sector_t raid0_size(mddev_t *mddev, sector_t sectors, int raid_disks)
296 {
297         sector_t array_sectors = 0;
298         mdk_rdev_t *rdev;
299
300         WARN_ONCE(sectors || raid_disks,
301                   "%s does not support generic reshape\n", __func__);
302
303         list_for_each_entry(rdev, &mddev->disks, same_set)
304                 array_sectors += rdev->sectors;
305
306         return array_sectors;
307 }
308
309 static int raid0_run(mddev_t *mddev)
310 {
311         int ret;
312
313         if (mddev->chunk_sectors == 0) {
314                 printk(KERN_ERR "md/raid0: chunk size must be set.\n");
315                 return -EINVAL;
316         }
317         if (md_check_no_bitmap(mddev))
318                 return -EINVAL;
319         blk_queue_max_sectors(mddev->queue, mddev->chunk_sectors);
320         mddev->queue->queue_lock = &mddev->queue->__queue_lock;
321
322         ret = create_strip_zones(mddev);
323         if (ret < 0)
324                 return ret;
325
326         /* calculate array device size */
327         md_set_array_sectors(mddev, raid0_size(mddev, 0, 0));
328
329         printk(KERN_INFO "raid0 : md_size is %llu sectors.\n",
330                 (unsigned long long)mddev->array_sectors);
331         /* calculate the max read-ahead size.
332          * For read-ahead of large files to be effective, we need to
333          * readahead at least twice a whole stripe. i.e. number of devices
334          * multiplied by chunk size times 2.
335          * If an individual device has an ra_pages greater than the
336          * chunk size, then we will not drive that device as hard as it
337          * wants.  We consider this a configuration error: a larger
338          * chunksize should be used in that case.
339          */
340         {
341                 int stripe = mddev->raid_disks *
342                         (mddev->chunk_sectors << 9) / PAGE_SIZE;
343                 if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)
344                         mddev->queue->backing_dev_info.ra_pages = 2* stripe;
345         }
346
347         blk_queue_merge_bvec(mddev->queue, raid0_mergeable_bvec);
348         dump_zones(mddev);
349         return 0;
350 }
351
352 static int raid0_stop(mddev_t *mddev)
353 {
354         raid0_conf_t *conf = mddev->private;
355
356         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
357         kfree(conf->strip_zone);
358         kfree(conf->devlist);
359         kfree(conf);
360         mddev->private = NULL;
361         return 0;
362 }
363
364 /* Find the zone which holds a particular offset
365  * Update *sectorp to be an offset in that zone
366  */
367 static struct strip_zone *find_zone(struct raid0_private_data *conf,
368                                     sector_t *sectorp)
369 {
370         int i;
371         struct strip_zone *z = conf->strip_zone;
372         sector_t sector = *sectorp;
373
374         for (i = 0; i < conf->nr_strip_zones; i++)
375                 if (sector < z[i].zone_end) {
376                         if (i)
377                                 *sectorp = sector - z[i-1].zone_end;
378                         return z + i;
379                 }
380         BUG();
381 }
382
383 /*
384  * remaps the bio to the target device. we separate two flows.
385  * power 2 flow and a general flow for the sake of perfromance
386 */
387 static mdk_rdev_t *map_sector(mddev_t *mddev, struct strip_zone *zone,
388                                 sector_t sector, sector_t *sector_offset)
389 {
390         unsigned int sect_in_chunk;
391         sector_t chunk;
392         raid0_conf_t *conf = mddev->private;
393         unsigned int chunk_sects = mddev->chunk_sectors;
394
395         if (is_power_of_2(chunk_sects)) {
396                 int chunksect_bits = ffz(~chunk_sects);
397                 /* find the sector offset inside the chunk */
398                 sect_in_chunk  = sector & (chunk_sects - 1);
399                 sector >>= chunksect_bits;
400                 /* chunk in zone */
401                 chunk = *sector_offset;
402                 /* quotient is the chunk in real device*/
403                 sector_div(chunk, zone->nb_dev << chunksect_bits);
404         } else{
405                 sect_in_chunk = sector_div(sector, chunk_sects);
406                 chunk = *sector_offset;
407                 sector_div(chunk, chunk_sects * zone->nb_dev);
408         }
409         /*
410         *  position the bio over the real device
411         *  real sector = chunk in device + starting of zone
412         *       + the position in the chunk
413         */
414         *sector_offset = (chunk * chunk_sects) + sect_in_chunk;
415         return conf->devlist[(zone - conf->strip_zone)*mddev->raid_disks
416                              + sector_div(sector, zone->nb_dev)];
417 }
418
419 /*
420  * Is io distribute over 1 or more chunks ?
421 */
422 static inline int is_io_in_chunk_boundary(mddev_t *mddev,
423                         unsigned int chunk_sects, struct bio *bio)
424 {
425         if (likely(is_power_of_2(chunk_sects))) {
426                 return chunk_sects >= ((bio->bi_sector & (chunk_sects-1))
427                                         + (bio->bi_size >> 9));
428         } else{
429                 sector_t sector = bio->bi_sector;
430                 return chunk_sects >= (sector_div(sector, chunk_sects)
431                                                 + (bio->bi_size >> 9));
432         }
433 }
434
435 static int raid0_make_request(struct request_queue *q, struct bio *bio)
436 {
437         mddev_t *mddev = q->queuedata;
438         unsigned int chunk_sects;
439         sector_t sector_offset;
440         struct strip_zone *zone;
441         mdk_rdev_t *tmp_dev;
442         const int rw = bio_data_dir(bio);
443         int cpu;
444
445         if (unlikely(bio_barrier(bio))) {
446                 bio_endio(bio, -EOPNOTSUPP);
447                 return 0;
448         }
449
450         cpu = part_stat_lock();
451         part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]);
452         part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw],
453                       bio_sectors(bio));
454         part_stat_unlock();
455
456         chunk_sects = mddev->chunk_sectors;
457         if (unlikely(!is_io_in_chunk_boundary(mddev, chunk_sects, bio))) {
458                 sector_t sector = bio->bi_sector;
459                 struct bio_pair *bp;
460                 /* Sanity check -- queue functions should prevent this happening */
461                 if (bio->bi_vcnt != 1 ||
462                     bio->bi_idx != 0)
463                         goto bad_map;
464                 /* This is a one page bio that upper layers
465                  * refuse to split for us, so we need to split it.
466                  */
467                 if (likely(is_power_of_2(chunk_sects)))
468                         bp = bio_split(bio, chunk_sects - (sector &
469                                                            (chunk_sects-1)));
470                 else
471                         bp = bio_split(bio, chunk_sects -
472                                        sector_div(sector, chunk_sects));
473                 if (raid0_make_request(q, &bp->bio1))
474                         generic_make_request(&bp->bio1);
475                 if (raid0_make_request(q, &bp->bio2))
476                         generic_make_request(&bp->bio2);
477
478                 bio_pair_release(bp);
479                 return 0;
480         }
481
482         sector_offset = bio->bi_sector;
483         zone =  find_zone(mddev->private, &sector_offset);
484         tmp_dev = map_sector(mddev, zone, bio->bi_sector,
485                              &sector_offset);
486         bio->bi_bdev = tmp_dev->bdev;
487         bio->bi_sector = sector_offset + zone->dev_start +
488                 tmp_dev->data_offset;
489         /*
490          * Let the main block layer submit the IO and resolve recursion:
491          */
492         return 1;
493
494 bad_map:
495         printk("raid0_make_request bug: can't convert block across chunks"
496                 " or bigger than %dk %llu %d\n", chunk_sects / 2,
497                 (unsigned long long)bio->bi_sector, bio->bi_size >> 10);
498
499         bio_io_error(bio);
500         return 0;
501 }
502
503 static void raid0_status(struct seq_file *seq, mddev_t *mddev)
504 {
505 #undef MD_DEBUG
506 #ifdef MD_DEBUG
507         int j, k, h;
508         char b[BDEVNAME_SIZE];
509         raid0_conf_t *conf = mddev->private;
510
511         sector_t zone_size;
512         sector_t zone_start = 0;
513         h = 0;
514
515         for (j = 0; j < conf->nr_strip_zones; j++) {
516                 seq_printf(seq, "      z%d", j);
517                 seq_printf(seq, "=[");
518                 for (k = 0; k < conf->strip_zone[j].nb_dev; k++)
519                         seq_printf(seq, "%s/", bdevname(
520                                 conf->devlist[j*mddev->raid_disks + k]
521                                                 ->bdev, b));
522
523                 zone_size  = conf->strip_zone[j].zone_end - zone_start;
524                 seq_printf(seq, "] ze=%lld ds=%lld s=%lld\n",
525                         (unsigned long long)zone_start>>1,
526                         (unsigned long long)conf->strip_zone[j].dev_start>>1,
527                         (unsigned long long)zone_size>>1);
528                 zone_start = conf->strip_zone[j].zone_end;
529         }
530 #endif
531         seq_printf(seq, " %dk chunks", mddev->chunk_sectors / 2);
532         return;
533 }
534
535 static struct mdk_personality raid0_personality=
536 {
537         .name           = "raid0",
538         .level          = 0,
539         .owner          = THIS_MODULE,
540         .make_request   = raid0_make_request,
541         .run            = raid0_run,
542         .stop           = raid0_stop,
543         .status         = raid0_status,
544         .size           = raid0_size,
545 };
546
547 static int __init raid0_init (void)
548 {
549         return register_md_personality (&raid0_personality);
550 }
551
552 static void raid0_exit (void)
553 {
554         unregister_md_personality (&raid0_personality);
555 }
556
557 module_init(raid0_init);
558 module_exit(raid0_exit);
559 MODULE_LICENSE("GPL");
560 MODULE_ALIAS("md-personality-2"); /* RAID0 */
561 MODULE_ALIAS("md-raid0");
562 MODULE_ALIAS("md-level-0");