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[POWERPC] Update pSeries defconfig for SATA
[firewire-audio.git] / drivers / md / multipath.c
blob171ff41b52b053e7acdc2f6c78e0ef34ed2bd695
1 /*
2 * multipath.c : Multiple Devices driver for Linux
3 *
4 * Copyright (C) 1999, 2000, 2001 Ingo Molnar, Red Hat
5 *
6 * Copyright (C) 1996, 1997, 1998 Ingo Molnar, Miguel de Icaza, Gadi Oxman
7 *
8 * MULTIPATH management functions.
9 *
10 * derived from raid1.c.
11 *
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License as published by
14 * the Free Software Foundation; either version 2, or (at your option)
15 * any later version.
16 *
17 * You should have received a copy of the GNU General Public License
18 * (for example /usr/src/linux/COPYING); if not, write to the Free
19 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20 */
21
22 #include <linux/module.h>
23 #include <linux/slab.h>
24 #include <linux/spinlock.h>
25 #include <linux/raid/multipath.h>
26 #include <linux/buffer_head.h>
27 #include <asm/atomic.h>
28
29 #define MAJOR_NR MD_MAJOR
30 #define MD_DRIVER
31 #define MD_PERSONALITY
32
33 #define MAX_WORK_PER_DISK 128
34
35 #define NR_RESERVED_BUFS 32
36
37
38 static int multipath_map (multipath_conf_t *conf)
39 {
40 int i, disks = conf->raid_disks;
41
42 /*
43 * Later we do read balancing on the read side
44 * now we use the first available disk.
45 */
46
47 rcu_read_lock();
48 for (i = 0; i < disks; i++) {
49 mdk_rdev_t *rdev = rcu_dereference(conf->multipaths[i].rdev);
50 if (rdev && test_bit(In_sync, &rdev->flags)) {
51 atomic_inc(&rdev->nr_pending);
52 rcu_read_unlock();
53 return i;
54 }
55 }
56 rcu_read_unlock();
57
58 printk(KERN_ERR "multipath_map(): no more operational IO paths?\n");
59 return (-1);
60 }
61
62 static void multipath_reschedule_retry (struct multipath_bh *mp_bh)
63 {
64 unsigned long flags;
65 mddev_t *mddev = mp_bh->mddev;
66 multipath_conf_t *conf = mddev_to_conf(mddev);
67
68 spin_lock_irqsave(&conf->device_lock, flags);
69 list_add(&mp_bh->retry_list, &conf->retry_list);
70 spin_unlock_irqrestore(&conf->device_lock, flags);
71 md_wakeup_thread(mddev->thread);
72 }
73
74
75 /*
76 * multipath_end_bh_io() is called when we have finished servicing a multipathed
77 * operation and are ready to return a success/failure code to the buffer
78 * cache layer.
79 */
80 static void multipath_end_bh_io (struct multipath_bh *mp_bh, int err)
81 {
82 struct bio *bio = mp_bh->master_bio;
83 multipath_conf_t *conf = mddev_to_conf(mp_bh->mddev);
84
85 bio_endio(bio, bio->bi_size, err);
86 mempool_free(mp_bh, conf->pool);
87 }
88
89 static int multipath_end_request(struct bio *bio, unsigned int bytes_done,
90 int error)
91 {
92 int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
93 struct multipath_bh * mp_bh = (struct multipath_bh *)(bio->bi_private);
94 multipath_conf_t *conf = mddev_to_conf(mp_bh->mddev);
95 mdk_rdev_t *rdev = conf->multipaths[mp_bh->path].rdev;
96
97 if (bio->bi_size)
98 return 1;
99
100 if (uptodate)
101 multipath_end_bh_io(mp_bh, 0);
102 else if (!bio_rw_ahead(bio)) {
103 /*
104 * oops, IO error:
105 */
106 char b[BDEVNAME_SIZE];
107 md_error (mp_bh->mddev, rdev);
108 printk(KERN_ERR "multipath: %s: rescheduling sector %llu\n",
109 bdevname(rdev->bdev,b),
110 (unsigned long long)bio->bi_sector);
111 multipath_reschedule_retry(mp_bh);
112 } else
113 multipath_end_bh_io(mp_bh, error);
114 rdev_dec_pending(rdev, conf->mddev);
115 return 0;
116 }
117
118 static void unplug_slaves(mddev_t *mddev)
119 {
120 multipath_conf_t *conf = mddev_to_conf(mddev);
121 int i;
122
123 rcu_read_lock();
124 for (i=0; i<mddev->raid_disks; i++) {
125 mdk_rdev_t *rdev = rcu_dereference(conf->multipaths[i].rdev);
126 if (rdev && !test_bit(Faulty, &rdev->flags)
127 && atomic_read(&rdev->nr_pending)) {
128 request_queue_t *r_queue = bdev_get_queue(rdev->bdev);
129
130 atomic_inc(&rdev->nr_pending);
131 rcu_read_unlock();
132
133 if (r_queue->unplug_fn)
134 r_queue->unplug_fn(r_queue);
135
136 rdev_dec_pending(rdev, mddev);
137 rcu_read_lock();
138 }
139 }
140 rcu_read_unlock();
141 }
142
143 static void multipath_unplug(request_queue_t *q)
144 {
145 unplug_slaves(q->queuedata);
146 }
147
148
149 static int multipath_make_request (request_queue_t *q, struct bio * bio)
150 {
151 mddev_t *mddev = q->queuedata;
152 multipath_conf_t *conf = mddev_to_conf(mddev);
153 struct multipath_bh * mp_bh;
154 struct multipath_info *multipath;
155 const int rw = bio_data_dir(bio);
156
157 if (unlikely(bio_barrier(bio))) {
158 bio_endio(bio, bio->bi_size, -EOPNOTSUPP);
159 return 0;
160 }
161
162 mp_bh = mempool_alloc(conf->pool, GFP_NOIO);
163
164 mp_bh->master_bio = bio;
165 mp_bh->mddev = mddev;
166
167 disk_stat_inc(mddev->gendisk, ios[rw]);
168 disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bio));
169
170 mp_bh->path = multipath_map(conf);
171 if (mp_bh->path < 0) {
172 bio_endio(bio, bio->bi_size, -EIO);
173 mempool_free(mp_bh, conf->pool);
174 return 0;
175 }
176 multipath = conf->multipaths + mp_bh->path;
177
178 mp_bh->bio = *bio;
179 mp_bh->bio.bi_sector += multipath->rdev->data_offset;
180 mp_bh->bio.bi_bdev = multipath->rdev->bdev;
181 mp_bh->bio.bi_rw |= (1 << BIO_RW_FAILFAST);
182 mp_bh->bio.bi_end_io = multipath_end_request;
183 mp_bh->bio.bi_private = mp_bh;
184 generic_make_request(&mp_bh->bio);
185 return 0;
186 }
187
188 static void multipath_status (struct seq_file *seq, mddev_t *mddev)
189 {
190 multipath_conf_t *conf = mddev_to_conf(mddev);
191 int i;
192
193 seq_printf (seq, " [%d/%d] [", conf->raid_disks,
194 conf->working_disks);
195 for (i = 0; i < conf->raid_disks; i++)
196 seq_printf (seq, "%s",
197 conf->multipaths[i].rdev &&
198 test_bit(In_sync, &conf->multipaths[i].rdev->flags) ? "U" : "_");
199 seq_printf (seq, "]");
200 }
201
202 static int multipath_issue_flush(request_queue_t *q, struct gendisk *disk,
203 sector_t *error_sector)
204 {
205 mddev_t *mddev = q->queuedata;
206 multipath_conf_t *conf = mddev_to_conf(mddev);
207 int i, ret = 0;
208
209 rcu_read_lock();
210 for (i=0; i<mddev->raid_disks && ret == 0; i++) {
211 mdk_rdev_t *rdev = rcu_dereference(conf->multipaths[i].rdev);
212 if (rdev && !test_bit(Faulty, &rdev->flags)) {
213 struct block_device *bdev = rdev->bdev;
214 request_queue_t *r_queue = bdev_get_queue(bdev);
215
216 if (!r_queue->issue_flush_fn)
217 ret = -EOPNOTSUPP;
218 else {
219 atomic_inc(&rdev->nr_pending);
220 rcu_read_unlock();
221 ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk,
222 error_sector);
223 rdev_dec_pending(rdev, mddev);
224 rcu_read_lock();
225 }
226 }
227 }
228 rcu_read_unlock();
229 return ret;
230 }
231 static int multipath_congested(void *data, int bits)
232 {
233 mddev_t *mddev = data;
234 multipath_conf_t *conf = mddev_to_conf(mddev);
235 int i, ret = 0;
236
237 rcu_read_lock();
238 for (i = 0; i < mddev->raid_disks ; i++) {
239 mdk_rdev_t *rdev = rcu_dereference(conf->multipaths[i].rdev);
240 if (rdev && !test_bit(Faulty, &rdev->flags)) {
241 request_queue_t *q = bdev_get_queue(rdev->bdev);
242
243 ret |= bdi_congested(&q->backing_dev_info, bits);
244 /* Just like multipath_map, we just check the
245 * first available device
246 */
247 break;
248 }
249 }
250 rcu_read_unlock();
251 return ret;
252 }
253
254 /*
255 * Careful, this can execute in IRQ contexts as well!
256 */
257 static void multipath_error (mddev_t *mddev, mdk_rdev_t *rdev)
258 {
259 multipath_conf_t *conf = mddev_to_conf(mddev);
260
261 if (conf->working_disks <= 1) {
262 /*
263 * Uh oh, we can do nothing if this is our last path, but
264 * first check if this is a queued request for a device
265 * which has just failed.
266 */
267 printk(KERN_ALERT
268 "multipath: only one IO path left and IO error.\n");
269 /* leave it active... it's all we have */
270 } else {
271 /*
272 * Mark disk as unusable
273 */
274 if (!test_bit(Faulty, &rdev->flags)) {
275 char b[BDEVNAME_SIZE];
276 clear_bit(In_sync, &rdev->flags);
277 set_bit(Faulty, &rdev->flags);
278 set_bit(MD_CHANGE_DEVS, &mddev->flags);
279 conf->working_disks--;
280 printk(KERN_ALERT "multipath: IO failure on %s,"
281 " disabling IO path. \n Operation continuing"
282 " on %d IO paths.\n",
283 bdevname (rdev->bdev,b),
284 conf->working_disks);
285 }
286 }
287 }
288
289 static void print_multipath_conf (multipath_conf_t *conf)
290 {
291 int i;
292 struct multipath_info *tmp;
293
294 printk("MULTIPATH conf printout:\n");
295 if (!conf) {
296 printk("(conf==NULL)\n");
297 return;
298 }
299 printk(" --- wd:%d rd:%d\n", conf->working_disks,
300 conf->raid_disks);
301
302 for (i = 0; i < conf->raid_disks; i++) {
303 char b[BDEVNAME_SIZE];
304 tmp = conf->multipaths + i;
305 if (tmp->rdev)
306 printk(" disk%d, o:%d, dev:%s\n",
307 i,!test_bit(Faulty, &tmp->rdev->flags),
308 bdevname(tmp->rdev->bdev,b));
309 }
310 }
311
312
313 static int multipath_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
314 {
315 multipath_conf_t *conf = mddev->private;
316 struct request_queue *q;
317 int found = 0;
318 int path;
319 struct multipath_info *p;
320
321 print_multipath_conf(conf);
322
323 for (path=0; path<mddev->raid_disks; path++)
324 if ((p=conf->multipaths+path)->rdev == NULL) {
325 q = rdev->bdev->bd_disk->queue;
326 blk_queue_stack_limits(mddev->queue, q);
327
328 /* as we don't honour merge_bvec_fn, we must never risk
329 * violating it, so limit ->max_sector to one PAGE, as
330 * a one page request is never in violation.
331 * (Note: it is very unlikely that a device with
332 * merge_bvec_fn will be involved in multipath.)
333 */
334 if (q->merge_bvec_fn &&
335 mddev->queue->max_sectors > (PAGE_SIZE>>9))
336 blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
337
338 conf->working_disks++;
339 rdev->raid_disk = path;
340 set_bit(In_sync, &rdev->flags);
341 rcu_assign_pointer(p->rdev, rdev);
342 found = 1;
343 }
344
345 print_multipath_conf(conf);
346 return found;
347 }
348
349 static int multipath_remove_disk(mddev_t *mddev, int number)
350 {
351 multipath_conf_t *conf = mddev->private;
352 int err = 0;
353 mdk_rdev_t *rdev;
354 struct multipath_info *p = conf->multipaths + number;
355
356 print_multipath_conf(conf);
357
358 rdev = p->rdev;
359 if (rdev) {
360 if (test_bit(In_sync, &rdev->flags) ||
361 atomic_read(&rdev->nr_pending)) {
362 printk(KERN_ERR "hot-remove-disk, slot %d is identified" " but is still operational!\n", number);
363 err = -EBUSY;
364 goto abort;
365 }
366 p->rdev = NULL;
367 synchronize_rcu();
368 if (atomic_read(&rdev->nr_pending)) {
369 /* lost the race, try later */
370 err = -EBUSY;
371 p->rdev = rdev;
372 }
373 }
374 abort:
375
376 print_multipath_conf(conf);
377 return err;
378 }
379
380
381
382 /*
383 * This is a kernel thread which:
384 *
385 * 1. Retries failed read operations on working multipaths.
386 * 2. Updates the raid superblock when problems encounter.
387 * 3. Performs writes following reads for array syncronising.
388 */
389
390 static void multipathd (mddev_t *mddev)
391 {
392 struct multipath_bh *mp_bh;
393 struct bio *bio;
394 unsigned long flags;
395 multipath_conf_t *conf = mddev_to_conf(mddev);
396 struct list_head *head = &conf->retry_list;
397
398 md_check_recovery(mddev);
399 for (;;) {
400 char b[BDEVNAME_SIZE];
401 spin_lock_irqsave(&conf->device_lock, flags);
402 if (list_empty(head))
403 break;
404 mp_bh = list_entry(head->prev, struct multipath_bh, retry_list);
405 list_del(head->prev);
406 spin_unlock_irqrestore(&conf->device_lock, flags);
407
408 bio = &mp_bh->bio;
409 bio->bi_sector = mp_bh->master_bio->bi_sector;
410
411 if ((mp_bh->path = multipath_map (conf))<0) {
412 printk(KERN_ALERT "multipath: %s: unrecoverable IO read"
413 " error for block %llu\n",
414 bdevname(bio->bi_bdev,b),
415 (unsigned long long)bio->bi_sector);
416 multipath_end_bh_io(mp_bh, -EIO);
417 } else {
418 printk(KERN_ERR "multipath: %s: redirecting sector %llu"
419 " to another IO path\n",
420 bdevname(bio->bi_bdev,b),
421 (unsigned long long)bio->bi_sector);
422 *bio = *(mp_bh->master_bio);
423 bio->bi_sector += conf->multipaths[mp_bh->path].rdev->data_offset;
424 bio->bi_bdev = conf->multipaths[mp_bh->path].rdev->bdev;
425 bio->bi_rw |= (1 << BIO_RW_FAILFAST);
426 bio->bi_end_io = multipath_end_request;
427 bio->bi_private = mp_bh;
428 generic_make_request(bio);
429 }
430 }
431 spin_unlock_irqrestore(&conf->device_lock, flags);
432 }
433
434 static int multipath_run (mddev_t *mddev)
435 {
436 multipath_conf_t *conf;
437 int disk_idx;
438 struct multipath_info *disk;
439 mdk_rdev_t *rdev;
440 struct list_head *tmp;
441
442 if (mddev->level != LEVEL_MULTIPATH) {
443 printk("multipath: %s: raid level not set to multipath IO (%d)\n",
444 mdname(mddev), mddev->level);
445 goto out;
446 }
447 /*
448 * copy the already verified devices into our private MULTIPATH
449 * bookkeeping area. [whatever we allocate in multipath_run(),
450 * should be freed in multipath_stop()]
451 */
452
453 conf = kzalloc(sizeof(multipath_conf_t), GFP_KERNEL);
454 mddev->private = conf;
455 if (!conf) {
456 printk(KERN_ERR
457 "multipath: couldn't allocate memory for %s\n",
458 mdname(mddev));
459 goto out;
460 }
461
462 conf->multipaths = kzalloc(sizeof(struct multipath_info)*mddev->raid_disks,
463 GFP_KERNEL);
464 if (!conf->multipaths) {
465 printk(KERN_ERR
466 "multipath: couldn't allocate memory for %s\n",
467 mdname(mddev));
468 goto out_free_conf;
469 }
470
471 conf->working_disks = 0;
472 ITERATE_RDEV(mddev,rdev,tmp) {
473 disk_idx = rdev->raid_disk;
474 if (disk_idx < 0 ||
475 disk_idx >= mddev->raid_disks)
476 continue;
477
478 disk = conf->multipaths + disk_idx;
479 disk->rdev = rdev;
480
481 blk_queue_stack_limits(mddev->queue,
482 rdev->bdev->bd_disk->queue);
483 /* as we don't honour merge_bvec_fn, we must never risk
484 * violating it, not that we ever expect a device with
485 * a merge_bvec_fn to be involved in multipath */
486 if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
487 mddev->queue->max_sectors > (PAGE_SIZE>>9))
488 blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
489
490 if (!test_bit(Faulty, &rdev->flags))
491 conf->working_disks++;
492 }
493
494 conf->raid_disks = mddev->raid_disks;
495 conf->mddev = mddev;
496 spin_lock_init(&conf->device_lock);
497 INIT_LIST_HEAD(&conf->retry_list);
498
499 if (!conf->working_disks) {
500 printk(KERN_ERR "multipath: no operational IO paths for %s\n",
501 mdname(mddev));
502 goto out_free_conf;
503 }
504 mddev->degraded = conf->raid_disks = conf->working_disks;
505
506 conf->pool = mempool_create_kzalloc_pool(NR_RESERVED_BUFS,
507 sizeof(struct multipath_bh));
508 if (conf->pool == NULL) {
509 printk(KERN_ERR
510 "multipath: couldn't allocate memory for %s\n",
511 mdname(mddev));
512 goto out_free_conf;
513 }
514
515 {
516 mddev->thread = md_register_thread(multipathd, mddev, "%s_multipath");
517 if (!mddev->thread) {
518 printk(KERN_ERR "multipath: couldn't allocate thread"
519 " for %s\n", mdname(mddev));
520 goto out_free_conf;
521 }
522 }
523
524 printk(KERN_INFO
525 "multipath: array %s active with %d out of %d IO paths\n",
526 mdname(mddev), conf->working_disks, mddev->raid_disks);
527 /*
528 * Ok, everything is just fine now
529 */
530 mddev->array_size = mddev->size;
531
532 mddev->queue->unplug_fn = multipath_unplug;
533 mddev->queue->issue_flush_fn = multipath_issue_flush;
534 mddev->queue->backing_dev_info.congested_fn = multipath_congested;
535 mddev->queue->backing_dev_info.congested_data = mddev;
536
537 return 0;
538
539 out_free_conf:
540 if (conf->pool)
541 mempool_destroy(conf->pool);
542 kfree(conf->multipaths);
543 kfree(conf);
544 mddev->private = NULL;
545 out:
546 return -EIO;
547 }
548
549
550 static int multipath_stop (mddev_t *mddev)
551 {
552 multipath_conf_t *conf = mddev_to_conf(mddev);
553
554 md_unregister_thread(mddev->thread);
555 mddev->thread = NULL;
556 blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
557 mempool_destroy(conf->pool);
558 kfree(conf->multipaths);
559 kfree(conf);
560 mddev->private = NULL;
561 return 0;
562 }
563
564 static struct mdk_personality multipath_personality =
565 {
566 .name = "multipath",
567 .level = LEVEL_MULTIPATH,
568 .owner = THIS_MODULE,
569 .make_request = multipath_make_request,
570 .run = multipath_run,
571 .stop = multipath_stop,
572 .status = multipath_status,
573 .error_handler = multipath_error,
574 .hot_add_disk = multipath_add_disk,
575 .hot_remove_disk= multipath_remove_disk,
576 };
577
578 static int __init multipath_init (void)
579 {
580 return register_md_personality (&multipath_personality);
581 }
582
583 static void __exit multipath_exit (void)
584 {
585 unregister_md_personality (&multipath_personality);
586 }
587
588 module_init(multipath_init);
589 module_exit(multipath_exit);
590 MODULE_LICENSE("GPL");
591 MODULE_ALIAS("md-personality-7"); /* MULTIPATH */
592 MODULE_ALIAS("md-multipath");
593 MODULE_ALIAS("md-level--4");
AMDTP streaming driver for the Linux FireWire stack (Juju)