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m68knommu: include linux/fs.h for do_pipe()
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / md / multipath.c
blob1e2af43a73b930b241ebffe2281f9afdad1444de
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 struct request_queue *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(struct request_queue *q)
144 {
145 unplug_slaves(q->queuedata);
146 }
147
148
149 static int multipath_make_request (struct request_queue *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(struct request_queue *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 struct request_queue *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 struct request_queue *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 mddev->degraded++;
281 printk(KERN_ALERT "multipath: IO failure on %s,"
282 " disabling IO path. \n Operation continuing"
283 " on %d IO paths.\n",
284 bdevname (rdev->bdev,b),
285 conf->working_disks);
286 }
287 }
288 }
289
290 static void print_multipath_conf (multipath_conf_t *conf)
291 {
292 int i;
293 struct multipath_info *tmp;
294
295 printk("MULTIPATH conf printout:\n");
296 if (!conf) {
297 printk("(conf==NULL)\n");
298 return;
299 }
300 printk(" --- wd:%d rd:%d\n", conf->working_disks,
301 conf->raid_disks);
302
303 for (i = 0; i < conf->raid_disks; i++) {
304 char b[BDEVNAME_SIZE];
305 tmp = conf->multipaths + i;
306 if (tmp->rdev)
307 printk(" disk%d, o:%d, dev:%s\n",
308 i,!test_bit(Faulty, &tmp->rdev->flags),
309 bdevname(tmp->rdev->bdev,b));
310 }
311 }
312
313
314 static int multipath_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
315 {
316 multipath_conf_t *conf = mddev->private;
317 struct request_queue *q;
318 int found = 0;
319 int path;
320 struct multipath_info *p;
321
322 print_multipath_conf(conf);
323
324 for (path=0; path<mddev->raid_disks; path++)
325 if ((p=conf->multipaths+path)->rdev == NULL) {
326 q = rdev->bdev->bd_disk->queue;
327 blk_queue_stack_limits(mddev->queue, q);
328
329 /* as we don't honour merge_bvec_fn, we must never risk
330 * violating it, so limit ->max_sector to one PAGE, as
331 * a one page request is never in violation.
332 * (Note: it is very unlikely that a device with
333 * merge_bvec_fn will be involved in multipath.)
334 */
335 if (q->merge_bvec_fn &&
336 mddev->queue->max_sectors > (PAGE_SIZE>>9))
337 blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
338
339 conf->working_disks++;
340 mddev->degraded--;
341 rdev->raid_disk = path;
342 set_bit(In_sync, &rdev->flags);
343 rcu_assign_pointer(p->rdev, rdev);
344 found = 1;
345 }
346
347 print_multipath_conf(conf);
348 return found;
349 }
350
351 static int multipath_remove_disk(mddev_t *mddev, int number)
352 {
353 multipath_conf_t *conf = mddev->private;
354 int err = 0;
355 mdk_rdev_t *rdev;
356 struct multipath_info *p = conf->multipaths + number;
357
358 print_multipath_conf(conf);
359
360 rdev = p->rdev;
361 if (rdev) {
362 if (test_bit(In_sync, &rdev->flags) ||
363 atomic_read(&rdev->nr_pending)) {
364 printk(KERN_ERR "hot-remove-disk, slot %d is identified" " but is still operational!\n", number);
365 err = -EBUSY;
366 goto abort;
367 }
368 p->rdev = NULL;
369 synchronize_rcu();
370 if (atomic_read(&rdev->nr_pending)) {
371 /* lost the race, try later */
372 err = -EBUSY;
373 p->rdev = rdev;
374 }
375 }
376 abort:
377
378 print_multipath_conf(conf);
379 return err;
380 }
381
382
383
384 /*
385 * This is a kernel thread which:
386 *
387 * 1. Retries failed read operations on working multipaths.
388 * 2. Updates the raid superblock when problems encounter.
389 * 3. Performs writes following reads for array syncronising.
390 */
391
392 static void multipathd (mddev_t *mddev)
393 {
394 struct multipath_bh *mp_bh;
395 struct bio *bio;
396 unsigned long flags;
397 multipath_conf_t *conf = mddev_to_conf(mddev);
398 struct list_head *head = &conf->retry_list;
399
400 md_check_recovery(mddev);
401 for (;;) {
402 char b[BDEVNAME_SIZE];
403 spin_lock_irqsave(&conf->device_lock, flags);
404 if (list_empty(head))
405 break;
406 mp_bh = list_entry(head->prev, struct multipath_bh, retry_list);
407 list_del(head->prev);
408 spin_unlock_irqrestore(&conf->device_lock, flags);
409
410 bio = &mp_bh->bio;
411 bio->bi_sector = mp_bh->master_bio->bi_sector;
412
413 if ((mp_bh->path = multipath_map (conf))<0) {
414 printk(KERN_ALERT "multipath: %s: unrecoverable IO read"
415 " error for block %llu\n",
416 bdevname(bio->bi_bdev,b),
417 (unsigned long long)bio->bi_sector);
418 multipath_end_bh_io(mp_bh, -EIO);
419 } else {
420 printk(KERN_ERR "multipath: %s: redirecting sector %llu"
421 " to another IO path\n",
422 bdevname(bio->bi_bdev,b),
423 (unsigned long long)bio->bi_sector);
424 *bio = *(mp_bh->master_bio);
425 bio->bi_sector += conf->multipaths[mp_bh->path].rdev->data_offset;
426 bio->bi_bdev = conf->multipaths[mp_bh->path].rdev->bdev;
427 bio->bi_rw |= (1 << BIO_RW_FAILFAST);
428 bio->bi_end_io = multipath_end_request;
429 bio->bi_private = mp_bh;
430 generic_make_request(bio);
431 }
432 }
433 spin_unlock_irqrestore(&conf->device_lock, flags);
434 }
435
436 static int multipath_run (mddev_t *mddev)
437 {
438 multipath_conf_t *conf;
439 int disk_idx;
440 struct multipath_info *disk;
441 mdk_rdev_t *rdev;
442 struct list_head *tmp;
443
444 if (mddev->level != LEVEL_MULTIPATH) {
445 printk("multipath: %s: raid level not set to multipath IO (%d)\n",
446 mdname(mddev), mddev->level);
447 goto out;
448 }
449 /*
450 * copy the already verified devices into our private MULTIPATH
451 * bookkeeping area. [whatever we allocate in multipath_run(),
452 * should be freed in multipath_stop()]
453 */
454
455 conf = kzalloc(sizeof(multipath_conf_t), GFP_KERNEL);
456 mddev->private = conf;
457 if (!conf) {
458 printk(KERN_ERR
459 "multipath: couldn't allocate memory for %s\n",
460 mdname(mddev));
461 goto out;
462 }
463
464 conf->multipaths = kzalloc(sizeof(struct multipath_info)*mddev->raid_disks,
465 GFP_KERNEL);
466 if (!conf->multipaths) {
467 printk(KERN_ERR
468 "multipath: couldn't allocate memory for %s\n",
469 mdname(mddev));
470 goto out_free_conf;
471 }
472
473 conf->working_disks = 0;
474 ITERATE_RDEV(mddev,rdev,tmp) {
475 disk_idx = rdev->raid_disk;
476 if (disk_idx < 0 ||
477 disk_idx >= mddev->raid_disks)
478 continue;
479
480 disk = conf->multipaths + disk_idx;
481 disk->rdev = rdev;
482
483 blk_queue_stack_limits(mddev->queue,
484 rdev->bdev->bd_disk->queue);
485 /* as we don't honour merge_bvec_fn, we must never risk
486 * violating it, not that we ever expect a device with
487 * a merge_bvec_fn to be involved in multipath */
488 if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
489 mddev->queue->max_sectors > (PAGE_SIZE>>9))
490 blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
491
492 if (!test_bit(Faulty, &rdev->flags))
493 conf->working_disks++;
494 }
495
496 conf->raid_disks = mddev->raid_disks;
497 conf->mddev = mddev;
498 spin_lock_init(&conf->device_lock);
499 INIT_LIST_HEAD(&conf->retry_list);
500
501 if (!conf->working_disks) {
502 printk(KERN_ERR "multipath: no operational IO paths for %s\n",
503 mdname(mddev));
504 goto out_free_conf;
505 }
506 mddev->degraded = conf->raid_disks - conf->working_disks;
507
508 conf->pool = mempool_create_kzalloc_pool(NR_RESERVED_BUFS,
509 sizeof(struct multipath_bh));
510 if (conf->pool == NULL) {
511 printk(KERN_ERR
512 "multipath: couldn't allocate memory for %s\n",
513 mdname(mddev));
514 goto out_free_conf;
515 }
516
517 {
518 mddev->thread = md_register_thread(multipathd, mddev, "%s_multipath");
519 if (!mddev->thread) {
520 printk(KERN_ERR "multipath: couldn't allocate thread"
521 " for %s\n", mdname(mddev));
522 goto out_free_conf;
523 }
524 }
525
526 printk(KERN_INFO
527 "multipath: array %s active with %d out of %d IO paths\n",
528 mdname(mddev), conf->working_disks, mddev->raid_disks);
529 /*
530 * Ok, everything is just fine now
531 */
532 mddev->array_size = mddev->size;
533
534 mddev->queue->unplug_fn = multipath_unplug;
535 mddev->queue->issue_flush_fn = multipath_issue_flush;
536 mddev->queue->backing_dev_info.congested_fn = multipath_congested;
537 mddev->queue->backing_dev_info.congested_data = mddev;
538
539 return 0;
540
541 out_free_conf:
542 if (conf->pool)
543 mempool_destroy(conf->pool);
544 kfree(conf->multipaths);
545 kfree(conf);
546 mddev->private = NULL;
547 out:
548 return -EIO;
549 }
550
551
552 static int multipath_stop (mddev_t *mddev)
553 {
554 multipath_conf_t *conf = mddev_to_conf(mddev);
555
556 md_unregister_thread(mddev->thread);
557 mddev->thread = NULL;
558 blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
559 mempool_destroy(conf->pool);
560 kfree(conf->multipaths);
561 kfree(conf);
562 mddev->private = NULL;
563 return 0;
564 }
565
566 static struct mdk_personality multipath_personality =
567 {
568 .name = "multipath",
569 .level = LEVEL_MULTIPATH,
570 .owner = THIS_MODULE,
571 .make_request = multipath_make_request,
572 .run = multipath_run,
573 .stop = multipath_stop,
574 .status = multipath_status,
575 .error_handler = multipath_error,
576 .hot_add_disk = multipath_add_disk,
577 .hot_remove_disk= multipath_remove_disk,
578 };
579
580 static int __init multipath_init (void)
581 {
582 return register_md_personality (&multipath_personality);
583 }
584
585 static void __exit multipath_exit (void)
586 {
587 unregister_md_personality (&multipath_personality);
588 }
589
590 module_init(multipath_init);
591 module_exit(multipath_exit);
592 MODULE_LICENSE("GPL");
593 MODULE_ALIAS("md-personality-7"); /* MULTIPATH */
594 MODULE_ALIAS("md-multipath");
595 MODULE_ALIAS("md-level--4");
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