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ipv4: fix ip_rt_update_pmtu()
[linux/fpc-iii.git] / drivers / md / multipath.c
blob3a62d440e27b8105bb778d36950575f77fdd28a3
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/blkdev.h>
23 #include <linux/raid/md_u.h>
24 #include <linux/seq_file.h>
25 #include <linux/slab.h>
26 #include "md.h"
27 #include "multipath.h"
28
29 #define MAX_WORK_PER_DISK 128
30
31 #define NR_RESERVED_BUFS 32
32
33
34 static int multipath_map (multipath_conf_t *conf)
35 {
36 int i, disks = conf->raid_disks;
37
38 /*
39 * Later we do read balancing on the read side
40 * now we use the first available disk.
41 */
42
43 rcu_read_lock();
44 for (i = 0; i < disks; i++) {
45 mdk_rdev_t *rdev = rcu_dereference(conf->multipaths[i].rdev);
46 if (rdev && test_bit(In_sync, &rdev->flags)) {
47 atomic_inc(&rdev->nr_pending);
48 rcu_read_unlock();
49 return i;
50 }
51 }
52 rcu_read_unlock();
53
54 printk(KERN_ERR "multipath_map(): no more operational IO paths?\n");
55 return (-1);
56 }
57
58 static void multipath_reschedule_retry (struct multipath_bh *mp_bh)
59 {
60 unsigned long flags;
61 mddev_t *mddev = mp_bh->mddev;
62 multipath_conf_t *conf = mddev->private;
63
64 spin_lock_irqsave(&conf->device_lock, flags);
65 list_add(&mp_bh->retry_list, &conf->retry_list);
66 spin_unlock_irqrestore(&conf->device_lock, flags);
67 md_wakeup_thread(mddev->thread);
68 }
69
70
71 /*
72 * multipath_end_bh_io() is called when we have finished servicing a multipathed
73 * operation and are ready to return a success/failure code to the buffer
74 * cache layer.
75 */
76 static void multipath_end_bh_io (struct multipath_bh *mp_bh, int err)
77 {
78 struct bio *bio = mp_bh->master_bio;
79 multipath_conf_t *conf = mp_bh->mddev->private;
80
81 bio_endio(bio, err);
82 mempool_free(mp_bh, conf->pool);
83 }
84
85 static void multipath_end_request(struct bio *bio, int error)
86 {
87 int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
88 struct multipath_bh *mp_bh = bio->bi_private;
89 multipath_conf_t *conf = mp_bh->mddev->private;
90 mdk_rdev_t *rdev = conf->multipaths[mp_bh->path].rdev;
91
92 if (uptodate)
93 multipath_end_bh_io(mp_bh, 0);
94 else if (!(bio->bi_rw & REQ_RAHEAD)) {
95 /*
96 * oops, IO error:
97 */
98 char b[BDEVNAME_SIZE];
99 md_error (mp_bh->mddev, rdev);
100 printk(KERN_ERR "multipath: %s: rescheduling sector %llu\n",
101 bdevname(rdev->bdev,b),
102 (unsigned long long)bio->bi_sector);
103 multipath_reschedule_retry(mp_bh);
104 } else
105 multipath_end_bh_io(mp_bh, error);
106 rdev_dec_pending(rdev, conf->mddev);
107 }
108
109 static void unplug_slaves(mddev_t *mddev)
110 {
111 multipath_conf_t *conf = mddev->private;
112 int i;
113
114 rcu_read_lock();
115 for (i=0; i<mddev->raid_disks; i++) {
116 mdk_rdev_t *rdev = rcu_dereference(conf->multipaths[i].rdev);
117 if (rdev && !test_bit(Faulty, &rdev->flags)
118 && atomic_read(&rdev->nr_pending)) {
119 struct request_queue *r_queue = bdev_get_queue(rdev->bdev);
120
121 atomic_inc(&rdev->nr_pending);
122 rcu_read_unlock();
123
124 blk_unplug(r_queue);
125
126 rdev_dec_pending(rdev, mddev);
127 rcu_read_lock();
128 }
129 }
130 rcu_read_unlock();
131 }
132
133 static void multipath_unplug(struct request_queue *q)
134 {
135 unplug_slaves(q->queuedata);
136 }
137
138
139 static int multipath_make_request(mddev_t *mddev, struct bio * bio)
140 {
141 multipath_conf_t *conf = mddev->private;
142 struct multipath_bh * mp_bh;
143 struct multipath_info *multipath;
144
145 if (unlikely(bio->bi_rw & REQ_FLUSH)) {
146 md_flush_request(mddev, bio);
147 return 0;
148 }
149
150 mp_bh = mempool_alloc(conf->pool, GFP_NOIO);
151
152 mp_bh->master_bio = bio;
153 mp_bh->mddev = mddev;
154
155 mp_bh->path = multipath_map(conf);
156 if (mp_bh->path < 0) {
157 bio_endio(bio, -EIO);
158 mempool_free(mp_bh, conf->pool);
159 return 0;
160 }
161 multipath = conf->multipaths + mp_bh->path;
162
163 mp_bh->bio = *bio;
164 mp_bh->bio.bi_sector += multipath->rdev->data_offset;
165 mp_bh->bio.bi_bdev = multipath->rdev->bdev;
166 mp_bh->bio.bi_rw |= REQ_FAILFAST_TRANSPORT;
167 mp_bh->bio.bi_end_io = multipath_end_request;
168 mp_bh->bio.bi_private = mp_bh;
169 generic_make_request(&mp_bh->bio);
170 return 0;
171 }
172
173 static void multipath_status (struct seq_file *seq, mddev_t *mddev)
174 {
175 multipath_conf_t *conf = mddev->private;
176 int i;
177
178 seq_printf (seq, " [%d/%d] [", conf->raid_disks,
179 conf->working_disks);
180 for (i = 0; i < conf->raid_disks; i++)
181 seq_printf (seq, "%s",
182 conf->multipaths[i].rdev &&
183 test_bit(In_sync, &conf->multipaths[i].rdev->flags) ? "U" : "_");
184 seq_printf (seq, "]");
185 }
186
187 static int multipath_congested(void *data, int bits)
188 {
189 mddev_t *mddev = data;
190 multipath_conf_t *conf = mddev->private;
191 int i, ret = 0;
192
193 if (mddev_congested(mddev, bits))
194 return 1;
195
196 rcu_read_lock();
197 for (i = 0; i < mddev->raid_disks ; i++) {
198 mdk_rdev_t *rdev = rcu_dereference(conf->multipaths[i].rdev);
199 if (rdev && !test_bit(Faulty, &rdev->flags)) {
200 struct request_queue *q = bdev_get_queue(rdev->bdev);
201
202 ret |= bdi_congested(&q->backing_dev_info, bits);
203 /* Just like multipath_map, we just check the
204 * first available device
205 */
206 break;
207 }
208 }
209 rcu_read_unlock();
210 return ret;
211 }
212
213 /*
214 * Careful, this can execute in IRQ contexts as well!
215 */
216 static void multipath_error (mddev_t *mddev, mdk_rdev_t *rdev)
217 {
218 multipath_conf_t *conf = mddev->private;
219
220 if (conf->working_disks <= 1) {
221 /*
222 * Uh oh, we can do nothing if this is our last path, but
223 * first check if this is a queued request for a device
224 * which has just failed.
225 */
226 printk(KERN_ALERT
227 "multipath: only one IO path left and IO error.\n");
228 /* leave it active... it's all we have */
229 } else {
230 /*
231 * Mark disk as unusable
232 */
233 if (!test_bit(Faulty, &rdev->flags)) {
234 char b[BDEVNAME_SIZE];
235 clear_bit(In_sync, &rdev->flags);
236 set_bit(Faulty, &rdev->flags);
237 set_bit(MD_CHANGE_DEVS, &mddev->flags);
238 conf->working_disks--;
239 mddev->degraded++;
240 printk(KERN_ALERT "multipath: IO failure on %s,"
241 " disabling IO path.\n"
242 "multipath: Operation continuing"
243 " on %d IO paths.\n",
244 bdevname (rdev->bdev,b),
245 conf->working_disks);
246 }
247 }
248 }
249
250 static void print_multipath_conf (multipath_conf_t *conf)
251 {
252 int i;
253 struct multipath_info *tmp;
254
255 printk("MULTIPATH conf printout:\n");
256 if (!conf) {
257 printk("(conf==NULL)\n");
258 return;
259 }
260 printk(" --- wd:%d rd:%d\n", conf->working_disks,
261 conf->raid_disks);
262
263 for (i = 0; i < conf->raid_disks; i++) {
264 char b[BDEVNAME_SIZE];
265 tmp = conf->multipaths + i;
266 if (tmp->rdev)
267 printk(" disk%d, o:%d, dev:%s\n",
268 i,!test_bit(Faulty, &tmp->rdev->flags),
269 bdevname(tmp->rdev->bdev,b));
270 }
271 }
272
273
274 static int multipath_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
275 {
276 multipath_conf_t *conf = mddev->private;
277 struct request_queue *q;
278 int err = -EEXIST;
279 int path;
280 struct multipath_info *p;
281 int first = 0;
282 int last = mddev->raid_disks - 1;
283
284 if (rdev->raid_disk >= 0)
285 first = last = rdev->raid_disk;
286
287 print_multipath_conf(conf);
288
289 for (path = first; path <= last; path++)
290 if ((p=conf->multipaths+path)->rdev == NULL) {
291 q = rdev->bdev->bd_disk->queue;
292 disk_stack_limits(mddev->gendisk, rdev->bdev,
293 rdev->data_offset << 9);
294
295 /* as we don't honour merge_bvec_fn, we must never risk
296 * violating it, so limit ->max_segments to one, lying
297 * within a single page.
298 * (Note: it is very unlikely that a device with
299 * merge_bvec_fn will be involved in multipath.)
300 */
301 if (q->merge_bvec_fn) {
302 blk_queue_max_segments(mddev->queue, 1);
303 blk_queue_segment_boundary(mddev->queue,
304 PAGE_CACHE_SIZE - 1);
305 }
306
307 conf->working_disks++;
308 mddev->degraded--;
309 rdev->raid_disk = path;
310 set_bit(In_sync, &rdev->flags);
311 rcu_assign_pointer(p->rdev, rdev);
312 err = 0;
313 md_integrity_add_rdev(rdev, mddev);
314 break;
315 }
316
317 print_multipath_conf(conf);
318
319 return err;
320 }
321
322 static int multipath_remove_disk(mddev_t *mddev, int number)
323 {
324 multipath_conf_t *conf = mddev->private;
325 int err = 0;
326 mdk_rdev_t *rdev;
327 struct multipath_info *p = conf->multipaths + number;
328
329 print_multipath_conf(conf);
330
331 rdev = p->rdev;
332 if (rdev) {
333 if (test_bit(In_sync, &rdev->flags) ||
334 atomic_read(&rdev->nr_pending)) {
335 printk(KERN_ERR "hot-remove-disk, slot %d is identified"
336 " but is still operational!\n", number);
337 err = -EBUSY;
338 goto abort;
339 }
340 p->rdev = NULL;
341 synchronize_rcu();
342 if (atomic_read(&rdev->nr_pending)) {
343 /* lost the race, try later */
344 err = -EBUSY;
345 p->rdev = rdev;
346 goto abort;
347 }
348 md_integrity_register(mddev);
349 }
350 abort:
351
352 print_multipath_conf(conf);
353 return err;
354 }
355
356
357
358 /*
359 * This is a kernel thread which:
360 *
361 * 1. Retries failed read operations on working multipaths.
362 * 2. Updates the raid superblock when problems encounter.
363 * 3. Performs writes following reads for array syncronising.
364 */
365
366 static void multipathd (mddev_t *mddev)
367 {
368 struct multipath_bh *mp_bh;
369 struct bio *bio;
370 unsigned long flags;
371 multipath_conf_t *conf = mddev->private;
372 struct list_head *head = &conf->retry_list;
373
374 md_check_recovery(mddev);
375 for (;;) {
376 char b[BDEVNAME_SIZE];
377 spin_lock_irqsave(&conf->device_lock, flags);
378 if (list_empty(head))
379 break;
380 mp_bh = list_entry(head->prev, struct multipath_bh, retry_list);
381 list_del(head->prev);
382 spin_unlock_irqrestore(&conf->device_lock, flags);
383
384 bio = &mp_bh->bio;
385 bio->bi_sector = mp_bh->master_bio->bi_sector;
386
387 if ((mp_bh->path = multipath_map (conf))<0) {
388 printk(KERN_ALERT "multipath: %s: unrecoverable IO read"
389 " error for block %llu\n",
390 bdevname(bio->bi_bdev,b),
391 (unsigned long long)bio->bi_sector);
392 multipath_end_bh_io(mp_bh, -EIO);
393 } else {
394 printk(KERN_ERR "multipath: %s: redirecting sector %llu"
395 " to another IO path\n",
396 bdevname(bio->bi_bdev,b),
397 (unsigned long long)bio->bi_sector);
398 *bio = *(mp_bh->master_bio);
399 bio->bi_sector += conf->multipaths[mp_bh->path].rdev->data_offset;
400 bio->bi_bdev = conf->multipaths[mp_bh->path].rdev->bdev;
401 bio->bi_rw |= REQ_FAILFAST_TRANSPORT;
402 bio->bi_end_io = multipath_end_request;
403 bio->bi_private = mp_bh;
404 generic_make_request(bio);
405 }
406 }
407 spin_unlock_irqrestore(&conf->device_lock, flags);
408 }
409
410 static sector_t multipath_size(mddev_t *mddev, sector_t sectors, int raid_disks)
411 {
412 WARN_ONCE(sectors || raid_disks,
413 "%s does not support generic reshape\n", __func__);
414
415 return mddev->dev_sectors;
416 }
417
418 static int multipath_run (mddev_t *mddev)
419 {
420 multipath_conf_t *conf;
421 int disk_idx;
422 struct multipath_info *disk;
423 mdk_rdev_t *rdev;
424
425 if (md_check_no_bitmap(mddev))
426 return -EINVAL;
427
428 if (mddev->level != LEVEL_MULTIPATH) {
429 printk("multipath: %s: raid level not set to multipath IO (%d)\n",
430 mdname(mddev), mddev->level);
431 goto out;
432 }
433 /*
434 * copy the already verified devices into our private MULTIPATH
435 * bookkeeping area. [whatever we allocate in multipath_run(),
436 * should be freed in multipath_stop()]
437 */
438
439 conf = kzalloc(sizeof(multipath_conf_t), GFP_KERNEL);
440 mddev->private = conf;
441 if (!conf) {
442 printk(KERN_ERR
443 "multipath: couldn't allocate memory for %s\n",
444 mdname(mddev));
445 goto out;
446 }
447
448 conf->multipaths = kzalloc(sizeof(struct multipath_info)*mddev->raid_disks,
449 GFP_KERNEL);
450 if (!conf->multipaths) {
451 printk(KERN_ERR
452 "multipath: couldn't allocate memory for %s\n",
453 mdname(mddev));
454 goto out_free_conf;
455 }
456
457 conf->working_disks = 0;
458 list_for_each_entry(rdev, &mddev->disks, same_set) {
459 disk_idx = rdev->raid_disk;
460 if (disk_idx < 0 ||
461 disk_idx >= mddev->raid_disks)
462 continue;
463
464 disk = conf->multipaths + disk_idx;
465 disk->rdev = rdev;
466 disk_stack_limits(mddev->gendisk, rdev->bdev,
467 rdev->data_offset << 9);
468
469 /* as we don't honour merge_bvec_fn, we must never risk
470 * violating it, not that we ever expect a device with
471 * a merge_bvec_fn to be involved in multipath */
472 if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
473 blk_queue_max_segments(mddev->queue, 1);
474 blk_queue_segment_boundary(mddev->queue,
475 PAGE_CACHE_SIZE - 1);
476 }
477
478 if (!test_bit(Faulty, &rdev->flags))
479 conf->working_disks++;
480 }
481
482 conf->raid_disks = mddev->raid_disks;
483 conf->mddev = mddev;
484 spin_lock_init(&conf->device_lock);
485 INIT_LIST_HEAD(&conf->retry_list);
486
487 if (!conf->working_disks) {
488 printk(KERN_ERR "multipath: no operational IO paths for %s\n",
489 mdname(mddev));
490 goto out_free_conf;
491 }
492 mddev->degraded = conf->raid_disks - conf->working_disks;
493
494 conf->pool = mempool_create_kmalloc_pool(NR_RESERVED_BUFS,
495 sizeof(struct multipath_bh));
496 if (conf->pool == NULL) {
497 printk(KERN_ERR
498 "multipath: couldn't allocate memory for %s\n",
499 mdname(mddev));
500 goto out_free_conf;
501 }
502
503 {
504 mddev->thread = md_register_thread(multipathd, mddev, NULL);
505 if (!mddev->thread) {
506 printk(KERN_ERR "multipath: couldn't allocate thread"
507 " for %s\n", mdname(mddev));
508 goto out_free_conf;
509 }
510 }
511
512 printk(KERN_INFO
513 "multipath: array %s active with %d out of %d IO paths\n",
514 mdname(mddev), conf->working_disks, mddev->raid_disks);
515 /*
516 * Ok, everything is just fine now
517 */
518 md_set_array_sectors(mddev, multipath_size(mddev, 0, 0));
519
520 mddev->queue->unplug_fn = multipath_unplug;
521 mddev->queue->backing_dev_info.congested_fn = multipath_congested;
522 mddev->queue->backing_dev_info.congested_data = mddev;
523 md_integrity_register(mddev);
524 return 0;
525
526 out_free_conf:
527 if (conf->pool)
528 mempool_destroy(conf->pool);
529 kfree(conf->multipaths);
530 kfree(conf);
531 mddev->private = NULL;
532 out:
533 return -EIO;
534 }
535
536
537 static int multipath_stop (mddev_t *mddev)
538 {
539 multipath_conf_t *conf = mddev->private;
540
541 md_unregister_thread(mddev->thread);
542 mddev->thread = NULL;
543 blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
544 mempool_destroy(conf->pool);
545 kfree(conf->multipaths);
546 kfree(conf);
547 mddev->private = NULL;
548 return 0;
549 }
550
551 static struct mdk_personality multipath_personality =
552 {
553 .name = "multipath",
554 .level = LEVEL_MULTIPATH,
555 .owner = THIS_MODULE,
556 .make_request = multipath_make_request,
557 .run = multipath_run,
558 .stop = multipath_stop,
559 .status = multipath_status,
560 .error_handler = multipath_error,
561 .hot_add_disk = multipath_add_disk,
562 .hot_remove_disk= multipath_remove_disk,
563 .size = multipath_size,
564 };
565
566 static int __init multipath_init (void)
567 {
568 return register_md_personality (&multipath_personality);
569 }
570
571 static void __exit multipath_exit (void)
572 {
573 unregister_md_personality (&multipath_personality);
574 }
575
576 module_init(multipath_init);
577 module_exit(multipath_exit);
578 MODULE_LICENSE("GPL");
579 MODULE_DESCRIPTION("simple multi-path personality for MD");
580 MODULE_ALIAS("md-personality-7"); /* MULTIPATH */
581 MODULE_ALIAS("md-multipath");
582 MODULE_ALIAS("md-level--4");
Linux with added FPC-III support