blob: 1cc9de44ce86c2cce64c58fb72d8b3f33245a83f [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
Linus Torvalds1da177e2005-04-16 15:20:36 -070038static 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++) {
Suzanne Woodd6065f72005-11-08 21:39:27 -080049 mdk_rdev_t *rdev = rcu_dereference(conf->multipaths[i].rdev);
NeilBrownb2d444d2005-11-08 21:39:31 -080050 if (rdev && test_bit(In_sync, &rdev->flags)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -070051 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
62static 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 */
80static 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
Adrian Bunk75c96f82005-05-05 16:16:09 -070089static int multipath_end_request(struct bio *bio, unsigned int bytes_done,
90 int error)
Linus Torvalds1da177e2005-04-16 15:20:36 -070091{
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
118static 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++) {
Suzanne Woodd6065f72005-11-08 21:39:27 -0800125 mdk_rdev_t *rdev = rcu_dereference(conf->multipaths[i].rdev);
NeilBrownb2d444d2005-11-08 21:39:31 -0800126 if (rdev && !test_bit(Faulty, &rdev->flags)
127 && atomic_read(&rdev->nr_pending)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128 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
143static void multipath_unplug(request_queue_t *q)
144{
145 unplug_slaves(q->queuedata);
146}
147
148
149static 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;
Jens Axboea3623572005-11-01 09:26:16 +0100155 const int rw = bio_data_dir(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156
NeilBrowne5dcdd82005-09-09 16:23:41 -0700157 if (unlikely(bio_barrier(bio))) {
158 bio_endio(bio, bio->bi_size, -EOPNOTSUPP);
159 return 0;
160 }
161
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162 mp_bh = mempool_alloc(conf->pool, GFP_NOIO);
163
164 mp_bh->master_bio = bio;
165 mp_bh->mddev = mddev;
166
Jens Axboea3623572005-11-01 09:26:16 +0100167 disk_stat_inc(mddev->gendisk, ios[rw]);
168 disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bio));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700169
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
188static 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 &&
NeilBrownb2d444d2005-11-08 21:39:31 -0800198 test_bit(In_sync, &conf->multipaths[i].rdev->flags) ? "U" : "_");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700199 seq_printf (seq, "]");
200}
201
202static 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++) {
Suzanne Woodd6065f72005-11-08 21:39:27 -0800211 mdk_rdev_t *rdev = rcu_dereference(conf->multipaths[i].rdev);
NeilBrownb2d444d2005-11-08 21:39:31 -0800212 if (rdev && !test_bit(Faulty, &rdev->flags)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700213 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
232/*
233 * Careful, this can execute in IRQ contexts as well!
234 */
235static void multipath_error (mddev_t *mddev, mdk_rdev_t *rdev)
236{
237 multipath_conf_t *conf = mddev_to_conf(mddev);
238
239 if (conf->working_disks <= 1) {
240 /*
241 * Uh oh, we can do nothing if this is our last path, but
242 * first check if this is a queued request for a device
243 * which has just failed.
244 */
245 printk(KERN_ALERT
246 "multipath: only one IO path left and IO error.\n");
247 /* leave it active... it's all we have */
248 } else {
249 /*
250 * Mark disk as unusable
251 */
NeilBrownb2d444d2005-11-08 21:39:31 -0800252 if (!test_bit(Faulty, &rdev->flags)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700253 char b[BDEVNAME_SIZE];
NeilBrownb2d444d2005-11-08 21:39:31 -0800254 clear_bit(In_sync, &rdev->flags);
255 set_bit(Faulty, &rdev->flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256 mddev->sb_dirty = 1;
257 conf->working_disks--;
258 printk(KERN_ALERT "multipath: IO failure on %s,"
259 " disabling IO path. \n Operation continuing"
260 " on %d IO paths.\n",
261 bdevname (rdev->bdev,b),
262 conf->working_disks);
263 }
264 }
265}
266
267static void print_multipath_conf (multipath_conf_t *conf)
268{
269 int i;
270 struct multipath_info *tmp;
271
272 printk("MULTIPATH conf printout:\n");
273 if (!conf) {
274 printk("(conf==NULL)\n");
275 return;
276 }
277 printk(" --- wd:%d rd:%d\n", conf->working_disks,
278 conf->raid_disks);
279
280 for (i = 0; i < conf->raid_disks; i++) {
281 char b[BDEVNAME_SIZE];
282 tmp = conf->multipaths + i;
283 if (tmp->rdev)
284 printk(" disk%d, o:%d, dev:%s\n",
NeilBrownb2d444d2005-11-08 21:39:31 -0800285 i,!test_bit(Faulty, &tmp->rdev->flags),
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286 bdevname(tmp->rdev->bdev,b));
287 }
288}
289
290
291static int multipath_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
292{
293 multipath_conf_t *conf = mddev->private;
Jesper Juhl352d7682006-01-09 20:54:44 -0800294 struct request_queue *q;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700295 int found = 0;
296 int path;
297 struct multipath_info *p;
298
299 print_multipath_conf(conf);
300
301 for (path=0; path<mddev->raid_disks; path++)
302 if ((p=conf->multipaths+path)->rdev == NULL) {
Jesper Juhl352d7682006-01-09 20:54:44 -0800303 q = rdev->bdev->bd_disk->queue;
304 blk_queue_stack_limits(mddev->queue, q);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305
306 /* as we don't honour merge_bvec_fn, we must never risk
307 * violating it, so limit ->max_sector to one PAGE, as
308 * a one page request is never in violation.
309 * (Note: it is very unlikely that a device with
310 * merge_bvec_fn will be involved in multipath.)
311 */
Jesper Juhl352d7682006-01-09 20:54:44 -0800312 if (q->merge_bvec_fn &&
Linus Torvalds1da177e2005-04-16 15:20:36 -0700313 mddev->queue->max_sectors > (PAGE_SIZE>>9))
314 blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
315
316 conf->working_disks++;
317 rdev->raid_disk = path;
NeilBrownb2d444d2005-11-08 21:39:31 -0800318 set_bit(In_sync, &rdev->flags);
Suzanne Woodd6065f72005-11-08 21:39:27 -0800319 rcu_assign_pointer(p->rdev, rdev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320 found = 1;
321 }
322
323 print_multipath_conf(conf);
324 return found;
325}
326
327static int multipath_remove_disk(mddev_t *mddev, int number)
328{
329 multipath_conf_t *conf = mddev->private;
330 int err = 0;
331 mdk_rdev_t *rdev;
332 struct multipath_info *p = conf->multipaths + number;
333
334 print_multipath_conf(conf);
335
336 rdev = p->rdev;
337 if (rdev) {
NeilBrownb2d444d2005-11-08 21:39:31 -0800338 if (test_bit(In_sync, &rdev->flags) ||
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339 atomic_read(&rdev->nr_pending)) {
340 printk(KERN_ERR "hot-remove-disk, slot %d is identified" " but is still operational!\n", number);
341 err = -EBUSY;
342 goto abort;
343 }
344 p->rdev = NULL;
Paul E. McKenneyfbd568a3e2005-05-01 08:59:04 -0700345 synchronize_rcu();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700346 if (atomic_read(&rdev->nr_pending)) {
347 /* lost the race, try later */
348 err = -EBUSY;
349 p->rdev = rdev;
350 }
351 }
352abort:
353
354 print_multipath_conf(conf);
355 return err;
356}
357
358
359
360/*
361 * This is a kernel thread which:
362 *
363 * 1. Retries failed read operations on working multipaths.
364 * 2. Updates the raid superblock when problems encounter.
365 * 3. Performs writes following reads for array syncronising.
366 */
367
368static void multipathd (mddev_t *mddev)
369{
370 struct multipath_bh *mp_bh;
371 struct bio *bio;
372 unsigned long flags;
373 multipath_conf_t *conf = mddev_to_conf(mddev);
374 struct list_head *head = &conf->retry_list;
375
376 md_check_recovery(mddev);
377 for (;;) {
378 char b[BDEVNAME_SIZE];
379 spin_lock_irqsave(&conf->device_lock, flags);
380 if (list_empty(head))
381 break;
382 mp_bh = list_entry(head->prev, struct multipath_bh, retry_list);
383 list_del(head->prev);
384 spin_unlock_irqrestore(&conf->device_lock, flags);
385
386 bio = &mp_bh->bio;
387 bio->bi_sector = mp_bh->master_bio->bi_sector;
388
389 if ((mp_bh->path = multipath_map (conf))<0) {
390 printk(KERN_ALERT "multipath: %s: unrecoverable IO read"
391 " error for block %llu\n",
392 bdevname(bio->bi_bdev,b),
393 (unsigned long long)bio->bi_sector);
394 multipath_end_bh_io(mp_bh, -EIO);
395 } else {
396 printk(KERN_ERR "multipath: %s: redirecting sector %llu"
397 " to another IO path\n",
398 bdevname(bio->bi_bdev,b),
399 (unsigned long long)bio->bi_sector);
400 *bio = *(mp_bh->master_bio);
401 bio->bi_sector += conf->multipaths[mp_bh->path].rdev->data_offset;
402 bio->bi_bdev = conf->multipaths[mp_bh->path].rdev->bdev;
403 bio->bi_rw |= (1 << BIO_RW_FAILFAST);
404 bio->bi_end_io = multipath_end_request;
405 bio->bi_private = mp_bh;
406 generic_make_request(bio);
407 }
408 }
409 spin_unlock_irqrestore(&conf->device_lock, flags);
410}
411
412static int multipath_run (mddev_t *mddev)
413{
414 multipath_conf_t *conf;
415 int disk_idx;
416 struct multipath_info *disk;
417 mdk_rdev_t *rdev;
418 struct list_head *tmp;
419
420 if (mddev->level != LEVEL_MULTIPATH) {
421 printk("multipath: %s: raid level not set to multipath IO (%d)\n",
422 mdname(mddev), mddev->level);
423 goto out;
424 }
425 /*
426 * copy the already verified devices into our private MULTIPATH
427 * bookkeeping area. [whatever we allocate in multipath_run(),
428 * should be freed in multipath_stop()]
429 */
430
NeilBrown9ffae0c2006-01-06 00:20:32 -0800431 conf = kzalloc(sizeof(multipath_conf_t), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700432 mddev->private = conf;
433 if (!conf) {
434 printk(KERN_ERR
435 "multipath: couldn't allocate memory for %s\n",
436 mdname(mddev));
437 goto out;
438 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700439
NeilBrown9ffae0c2006-01-06 00:20:32 -0800440 conf->multipaths = kzalloc(sizeof(struct multipath_info)*mddev->raid_disks,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700441 GFP_KERNEL);
442 if (!conf->multipaths) {
443 printk(KERN_ERR
444 "multipath: couldn't allocate memory for %s\n",
445 mdname(mddev));
446 goto out_free_conf;
447 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448
Linus Torvalds1da177e2005-04-16 15:20:36 -0700449 conf->working_disks = 0;
450 ITERATE_RDEV(mddev,rdev,tmp) {
451 disk_idx = rdev->raid_disk;
452 if (disk_idx < 0 ||
453 disk_idx >= mddev->raid_disks)
454 continue;
455
456 disk = conf->multipaths + disk_idx;
457 disk->rdev = rdev;
458
459 blk_queue_stack_limits(mddev->queue,
460 rdev->bdev->bd_disk->queue);
461 /* as we don't honour merge_bvec_fn, we must never risk
462 * violating it, not that we ever expect a device with
463 * a merge_bvec_fn to be involved in multipath */
464 if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
465 mddev->queue->max_sectors > (PAGE_SIZE>>9))
466 blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
467
NeilBrownb2d444d2005-11-08 21:39:31 -0800468 if (!test_bit(Faulty, &rdev->flags))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700469 conf->working_disks++;
470 }
471
472 conf->raid_disks = mddev->raid_disks;
473 mddev->sb_dirty = 1;
474 conf->mddev = mddev;
475 spin_lock_init(&conf->device_lock);
476 INIT_LIST_HEAD(&conf->retry_list);
477
478 if (!conf->working_disks) {
479 printk(KERN_ERR "multipath: no operational IO paths for %s\n",
480 mdname(mddev));
481 goto out_free_conf;
482 }
483 mddev->degraded = conf->raid_disks = conf->working_disks;
484
Matthew Dobson26b6e052006-03-26 01:37:48 -0800485 conf->pool = mempool_create_kzalloc_pool(NR_RESERVED_BUFS,
486 sizeof(struct multipath_bh));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487 if (conf->pool == NULL) {
488 printk(KERN_ERR
489 "multipath: couldn't allocate memory for %s\n",
490 mdname(mddev));
491 goto out_free_conf;
492 }
493
494 {
495 mddev->thread = md_register_thread(multipathd, mddev, "%s_multipath");
496 if (!mddev->thread) {
497 printk(KERN_ERR "multipath: couldn't allocate thread"
498 " for %s\n", mdname(mddev));
499 goto out_free_conf;
500 }
501 }
502
503 printk(KERN_INFO
504 "multipath: array %s active with %d out of %d IO paths\n",
505 mdname(mddev), conf->working_disks, mddev->raid_disks);
506 /*
507 * Ok, everything is just fine now
508 */
509 mddev->array_size = mddev->size;
NeilBrown7a5febe2005-05-16 21:53:16 -0700510
511 mddev->queue->unplug_fn = multipath_unplug;
512 mddev->queue->issue_flush_fn = multipath_issue_flush;
513
Linus Torvalds1da177e2005-04-16 15:20:36 -0700514 return 0;
515
516out_free_conf:
517 if (conf->pool)
518 mempool_destroy(conf->pool);
Jesper Juhl990a8ba2005-06-21 17:17:30 -0700519 kfree(conf->multipaths);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700520 kfree(conf);
521 mddev->private = NULL;
522out:
523 return -EIO;
524}
525
526
527static int multipath_stop (mddev_t *mddev)
528{
529 multipath_conf_t *conf = mddev_to_conf(mddev);
530
531 md_unregister_thread(mddev->thread);
532 mddev->thread = NULL;
533 blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
534 mempool_destroy(conf->pool);
535 kfree(conf->multipaths);
536 kfree(conf);
537 mddev->private = NULL;
538 return 0;
539}
540
NeilBrown2604b702006-01-06 00:20:36 -0800541static struct mdk_personality multipath_personality =
Linus Torvalds1da177e2005-04-16 15:20:36 -0700542{
543 .name = "multipath",
NeilBrown2604b702006-01-06 00:20:36 -0800544 .level = LEVEL_MULTIPATH,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700545 .owner = THIS_MODULE,
546 .make_request = multipath_make_request,
547 .run = multipath_run,
548 .stop = multipath_stop,
549 .status = multipath_status,
550 .error_handler = multipath_error,
551 .hot_add_disk = multipath_add_disk,
552 .hot_remove_disk= multipath_remove_disk,
553};
554
555static int __init multipath_init (void)
556{
NeilBrown2604b702006-01-06 00:20:36 -0800557 return register_md_personality (&multipath_personality);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700558}
559
560static void __exit multipath_exit (void)
561{
NeilBrown2604b702006-01-06 00:20:36 -0800562 unregister_md_personality (&multipath_personality);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700563}
564
565module_init(multipath_init);
566module_exit(multipath_exit);
567MODULE_LICENSE("GPL");
568MODULE_ALIAS("md-personality-7"); /* MULTIPATH */
NeilBrownd9d166c2006-01-06 00:20:51 -0800569MODULE_ALIAS("md-multipath");
NeilBrown2604b702006-01-06 00:20:36 -0800570MODULE_ALIAS("md-level--4");