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[PATCH] usbcore: Improve endpoint sysfs file handling
[linux/fpc-iii.git] / drivers / md / multipath.c
blob1151c3ed300677e2be0fbed012ab27052527afb6
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 mdk_personality_t multipath_personality;
39
40
41 static void *mp_pool_alloc(gfp_t gfp_flags, void *data)
42 {
43 struct multipath_bh *mpb;
44 mpb = kmalloc(sizeof(*mpb), gfp_flags);
45 if (mpb)
46 memset(mpb, 0, sizeof(*mpb));
47 return mpb;
48 }
49
50 static void mp_pool_free(void *mpb, void *data)
51 {
52 kfree(mpb);
53 }
54
55 static int multipath_map (multipath_conf_t *conf)
56 {
57 int i, disks = conf->raid_disks;
58
59 /*
60 * Later we do read balancing on the read side
61 * now we use the first available disk.
62 */
63
64 rcu_read_lock();
65 for (i = 0; i < disks; i++) {
66 mdk_rdev_t *rdev = conf->multipaths[i].rdev;
67 if (rdev && rdev->in_sync) {
68 atomic_inc(&rdev->nr_pending);
69 rcu_read_unlock();
70 return i;
71 }
72 }
73 rcu_read_unlock();
74
75 printk(KERN_ERR "multipath_map(): no more operational IO paths?\n");
76 return (-1);
77 }
78
79 static void multipath_reschedule_retry (struct multipath_bh *mp_bh)
80 {
81 unsigned long flags;
82 mddev_t *mddev = mp_bh->mddev;
83 multipath_conf_t *conf = mddev_to_conf(mddev);
84
85 spin_lock_irqsave(&conf->device_lock, flags);
86 list_add(&mp_bh->retry_list, &conf->retry_list);
87 spin_unlock_irqrestore(&conf->device_lock, flags);
88 md_wakeup_thread(mddev->thread);
89 }
90
91
92 /*
93 * multipath_end_bh_io() is called when we have finished servicing a multipathed
94 * operation and are ready to return a success/failure code to the buffer
95 * cache layer.
96 */
97 static void multipath_end_bh_io (struct multipath_bh *mp_bh, int err)
98 {
99 struct bio *bio = mp_bh->master_bio;
100 multipath_conf_t *conf = mddev_to_conf(mp_bh->mddev);
101
102 bio_endio(bio, bio->bi_size, err);
103 mempool_free(mp_bh, conf->pool);
104 }
105
106 static int multipath_end_request(struct bio *bio, unsigned int bytes_done,
107 int error)
108 {
109 int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
110 struct multipath_bh * mp_bh = (struct multipath_bh *)(bio->bi_private);
111 multipath_conf_t *conf = mddev_to_conf(mp_bh->mddev);
112 mdk_rdev_t *rdev = conf->multipaths[mp_bh->path].rdev;
113
114 if (bio->bi_size)
115 return 1;
116
117 if (uptodate)
118 multipath_end_bh_io(mp_bh, 0);
119 else if (!bio_rw_ahead(bio)) {
120 /*
121 * oops, IO error:
122 */
123 char b[BDEVNAME_SIZE];
124 md_error (mp_bh->mddev, rdev);
125 printk(KERN_ERR "multipath: %s: rescheduling sector %llu\n",
126 bdevname(rdev->bdev,b),
127 (unsigned long long)bio->bi_sector);
128 multipath_reschedule_retry(mp_bh);
129 } else
130 multipath_end_bh_io(mp_bh, error);
131 rdev_dec_pending(rdev, conf->mddev);
132 return 0;
133 }
134
135 static void unplug_slaves(mddev_t *mddev)
136 {
137 multipath_conf_t *conf = mddev_to_conf(mddev);
138 int i;
139
140 rcu_read_lock();
141 for (i=0; i<mddev->raid_disks; i++) {
142 mdk_rdev_t *rdev = conf->multipaths[i].rdev;
143 if (rdev && !rdev->faulty && atomic_read(&rdev->nr_pending)) {
144 request_queue_t *r_queue = bdev_get_queue(rdev->bdev);
145
146 atomic_inc(&rdev->nr_pending);
147 rcu_read_unlock();
148
149 if (r_queue->unplug_fn)
150 r_queue->unplug_fn(r_queue);
151
152 rdev_dec_pending(rdev, mddev);
153 rcu_read_lock();
154 }
155 }
156 rcu_read_unlock();
157 }
158
159 static void multipath_unplug(request_queue_t *q)
160 {
161 unplug_slaves(q->queuedata);
162 }
163
164
165 static int multipath_make_request (request_queue_t *q, struct bio * bio)
166 {
167 mddev_t *mddev = q->queuedata;
168 multipath_conf_t *conf = mddev_to_conf(mddev);
169 struct multipath_bh * mp_bh;
170 struct multipath_info *multipath;
171
172 if (unlikely(bio_barrier(bio))) {
173 bio_endio(bio, bio->bi_size, -EOPNOTSUPP);
174 return 0;
175 }
176
177 mp_bh = mempool_alloc(conf->pool, GFP_NOIO);
178
179 mp_bh->master_bio = bio;
180 mp_bh->mddev = mddev;
181
182 if (bio_data_dir(bio)==WRITE) {
183 disk_stat_inc(mddev->gendisk, writes);
184 disk_stat_add(mddev->gendisk, write_sectors, bio_sectors(bio));
185 } else {
186 disk_stat_inc(mddev->gendisk, reads);
187 disk_stat_add(mddev->gendisk, read_sectors, bio_sectors(bio));
188 }
189
190 mp_bh->path = multipath_map(conf);
191 if (mp_bh->path < 0) {
192 bio_endio(bio, bio->bi_size, -EIO);
193 mempool_free(mp_bh, conf->pool);
194 return 0;
195 }
196 multipath = conf->multipaths + mp_bh->path;
197
198 mp_bh->bio = *bio;
199 mp_bh->bio.bi_sector += multipath->rdev->data_offset;
200 mp_bh->bio.bi_bdev = multipath->rdev->bdev;
201 mp_bh->bio.bi_rw |= (1 << BIO_RW_FAILFAST);
202 mp_bh->bio.bi_end_io = multipath_end_request;
203 mp_bh->bio.bi_private = mp_bh;
204 generic_make_request(&mp_bh->bio);
205 return 0;
206 }
207
208 static void multipath_status (struct seq_file *seq, mddev_t *mddev)
209 {
210 multipath_conf_t *conf = mddev_to_conf(mddev);
211 int i;
212
213 seq_printf (seq, " [%d/%d] [", conf->raid_disks,
214 conf->working_disks);
215 for (i = 0; i < conf->raid_disks; i++)
216 seq_printf (seq, "%s",
217 conf->multipaths[i].rdev &&
218 conf->multipaths[i].rdev->in_sync ? "U" : "_");
219 seq_printf (seq, "]");
220 }
221
222 static int multipath_issue_flush(request_queue_t *q, struct gendisk *disk,
223 sector_t *error_sector)
224 {
225 mddev_t *mddev = q->queuedata;
226 multipath_conf_t *conf = mddev_to_conf(mddev);
227 int i, ret = 0;
228
229 rcu_read_lock();
230 for (i=0; i<mddev->raid_disks && ret == 0; i++) {
231 mdk_rdev_t *rdev = conf->multipaths[i].rdev;
232 if (rdev && !rdev->faulty) {
233 struct block_device *bdev = rdev->bdev;
234 request_queue_t *r_queue = bdev_get_queue(bdev);
235
236 if (!r_queue->issue_flush_fn)
237 ret = -EOPNOTSUPP;
238 else {
239 atomic_inc(&rdev->nr_pending);
240 rcu_read_unlock();
241 ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk,
242 error_sector);
243 rdev_dec_pending(rdev, mddev);
244 rcu_read_lock();
245 }
246 }
247 }
248 rcu_read_unlock();
249 return ret;
250 }
251
252 /*
253 * Careful, this can execute in IRQ contexts as well!
254 */
255 static void multipath_error (mddev_t *mddev, mdk_rdev_t *rdev)
256 {
257 multipath_conf_t *conf = mddev_to_conf(mddev);
258
259 if (conf->working_disks <= 1) {
260 /*
261 * Uh oh, we can do nothing if this is our last path, but
262 * first check if this is a queued request for a device
263 * which has just failed.
264 */
265 printk(KERN_ALERT
266 "multipath: only one IO path left and IO error.\n");
267 /* leave it active... it's all we have */
268 } else {
269 /*
270 * Mark disk as unusable
271 */
272 if (!rdev->faulty) {
273 char b[BDEVNAME_SIZE];
274 rdev->in_sync = 0;
275 rdev->faulty = 1;
276 mddev->sb_dirty = 1;
277 conf->working_disks--;
278 printk(KERN_ALERT "multipath: IO failure on %s,"
279 " disabling IO path. \n Operation continuing"
280 " on %d IO paths.\n",
281 bdevname (rdev->bdev,b),
282 conf->working_disks);
283 }
284 }
285 }
286
287 static void print_multipath_conf (multipath_conf_t *conf)
288 {
289 int i;
290 struct multipath_info *tmp;
291
292 printk("MULTIPATH conf printout:\n");
293 if (!conf) {
294 printk("(conf==NULL)\n");
295 return;
296 }
297 printk(" --- wd:%d rd:%d\n", conf->working_disks,
298 conf->raid_disks);
299
300 for (i = 0; i < conf->raid_disks; i++) {
301 char b[BDEVNAME_SIZE];
302 tmp = conf->multipaths + i;
303 if (tmp->rdev)
304 printk(" disk%d, o:%d, dev:%s\n",
305 i,!tmp->rdev->faulty,
306 bdevname(tmp->rdev->bdev,b));
307 }
308 }
309
310
311 static int multipath_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
312 {
313 multipath_conf_t *conf = mddev->private;
314 int found = 0;
315 int path;
316 struct multipath_info *p;
317
318 print_multipath_conf(conf);
319
320 for (path=0; path<mddev->raid_disks; path++)
321 if ((p=conf->multipaths+path)->rdev == NULL) {
322 blk_queue_stack_limits(mddev->queue,
323 rdev->bdev->bd_disk->queue);
324
325 /* as we don't honour merge_bvec_fn, we must never risk
326 * violating it, so limit ->max_sector to one PAGE, as
327 * a one page request is never in violation.
328 * (Note: it is very unlikely that a device with
329 * merge_bvec_fn will be involved in multipath.)
330 */
331 if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
332 mddev->queue->max_sectors > (PAGE_SIZE>>9))
333 blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
334
335 conf->working_disks++;
336 rdev->raid_disk = path;
337 rdev->in_sync = 1;
338 p->rdev = rdev;
339 found = 1;
340 }
341
342 print_multipath_conf(conf);
343 return found;
344 }
345
346 static int multipath_remove_disk(mddev_t *mddev, int number)
347 {
348 multipath_conf_t *conf = mddev->private;
349 int err = 0;
350 mdk_rdev_t *rdev;
351 struct multipath_info *p = conf->multipaths + number;
352
353 print_multipath_conf(conf);
354
355 rdev = p->rdev;
356 if (rdev) {
357 if (rdev->in_sync ||
358 atomic_read(&rdev->nr_pending)) {
359 printk(KERN_ERR "hot-remove-disk, slot %d is identified" " but is still operational!\n", number);
360 err = -EBUSY;
361 goto abort;
362 }
363 p->rdev = NULL;
364 synchronize_rcu();
365 if (atomic_read(&rdev->nr_pending)) {
366 /* lost the race, try later */
367 err = -EBUSY;
368 p->rdev = rdev;
369 }
370 }
371 abort:
372
373 print_multipath_conf(conf);
374 return err;
375 }
376
377
378
379 /*
380 * This is a kernel thread which:
381 *
382 * 1. Retries failed read operations on working multipaths.
383 * 2. Updates the raid superblock when problems encounter.
384 * 3. Performs writes following reads for array syncronising.
385 */
386
387 static void multipathd (mddev_t *mddev)
388 {
389 struct multipath_bh *mp_bh;
390 struct bio *bio;
391 unsigned long flags;
392 multipath_conf_t *conf = mddev_to_conf(mddev);
393 struct list_head *head = &conf->retry_list;
394
395 md_check_recovery(mddev);
396 for (;;) {
397 char b[BDEVNAME_SIZE];
398 spin_lock_irqsave(&conf->device_lock, flags);
399 if (list_empty(head))
400 break;
401 mp_bh = list_entry(head->prev, struct multipath_bh, retry_list);
402 list_del(head->prev);
403 spin_unlock_irqrestore(&conf->device_lock, flags);
404
405 bio = &mp_bh->bio;
406 bio->bi_sector = mp_bh->master_bio->bi_sector;
407
408 if ((mp_bh->path = multipath_map (conf))<0) {
409 printk(KERN_ALERT "multipath: %s: unrecoverable IO read"
410 " error for block %llu\n",
411 bdevname(bio->bi_bdev,b),
412 (unsigned long long)bio->bi_sector);
413 multipath_end_bh_io(mp_bh, -EIO);
414 } else {
415 printk(KERN_ERR "multipath: %s: redirecting sector %llu"
416 " to another IO path\n",
417 bdevname(bio->bi_bdev,b),
418 (unsigned long long)bio->bi_sector);
419 *bio = *(mp_bh->master_bio);
420 bio->bi_sector += conf->multipaths[mp_bh->path].rdev->data_offset;
421 bio->bi_bdev = conf->multipaths[mp_bh->path].rdev->bdev;
422 bio->bi_rw |= (1 << BIO_RW_FAILFAST);
423 bio->bi_end_io = multipath_end_request;
424 bio->bi_private = mp_bh;
425 generic_make_request(bio);
426 }
427 }
428 spin_unlock_irqrestore(&conf->device_lock, flags);
429 }
430
431 static int multipath_run (mddev_t *mddev)
432 {
433 multipath_conf_t *conf;
434 int disk_idx;
435 struct multipath_info *disk;
436 mdk_rdev_t *rdev;
437 struct list_head *tmp;
438
439 if (mddev->level != LEVEL_MULTIPATH) {
440 printk("multipath: %s: raid level not set to multipath IO (%d)\n",
441 mdname(mddev), mddev->level);
442 goto out;
443 }
444 /*
445 * copy the already verified devices into our private MULTIPATH
446 * bookkeeping area. [whatever we allocate in multipath_run(),
447 * should be freed in multipath_stop()]
448 */
449
450 conf = kmalloc(sizeof(multipath_conf_t), GFP_KERNEL);
451 mddev->private = conf;
452 if (!conf) {
453 printk(KERN_ERR
454 "multipath: couldn't allocate memory for %s\n",
455 mdname(mddev));
456 goto out;
457 }
458 memset(conf, 0, sizeof(*conf));
459
460 conf->multipaths = kmalloc(sizeof(struct multipath_info)*mddev->raid_disks,
461 GFP_KERNEL);
462 if (!conf->multipaths) {
463 printk(KERN_ERR
464 "multipath: couldn't allocate memory for %s\n",
465 mdname(mddev));
466 goto out_free_conf;
467 }
468 memset(conf->multipaths, 0, sizeof(struct multipath_info)*mddev->raid_disks);
469
470 conf->working_disks = 0;
471 ITERATE_RDEV(mddev,rdev,tmp) {
472 disk_idx = rdev->raid_disk;
473 if (disk_idx < 0 ||
474 disk_idx >= mddev->raid_disks)
475 continue;
476
477 disk = conf->multipaths + disk_idx;
478 disk->rdev = rdev;
479
480 blk_queue_stack_limits(mddev->queue,
481 rdev->bdev->bd_disk->queue);
482 /* as we don't honour merge_bvec_fn, we must never risk
483 * violating it, not that we ever expect a device with
484 * a merge_bvec_fn to be involved in multipath */
485 if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
486 mddev->queue->max_sectors > (PAGE_SIZE>>9))
487 blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
488
489 if (!rdev->faulty)
490 conf->working_disks++;
491 }
492
493 conf->raid_disks = mddev->raid_disks;
494 mddev->sb_dirty = 1;
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(NR_RESERVED_BUFS,
507 mp_pool_alloc, mp_pool_free,
508 NULL);
509 if (conf->pool == NULL) {
510 printk(KERN_ERR
511 "multipath: couldn't allocate memory for %s\n",
512 mdname(mddev));
513 goto out_free_conf;
514 }
515
516 {
517 mddev->thread = md_register_thread(multipathd, mddev, "%s_multipath");
518 if (!mddev->thread) {
519 printk(KERN_ERR "multipath: couldn't allocate thread"
520 " for %s\n", mdname(mddev));
521 goto out_free_conf;
522 }
523 }
524
525 printk(KERN_INFO
526 "multipath: array %s active with %d out of %d IO paths\n",
527 mdname(mddev), conf->working_disks, mddev->raid_disks);
528 /*
529 * Ok, everything is just fine now
530 */
531 mddev->array_size = mddev->size;
532
533 mddev->queue->unplug_fn = multipath_unplug;
534 mddev->queue->issue_flush_fn = multipath_issue_flush;
535
536 return 0;
537
538 out_free_conf:
539 if (conf->pool)
540 mempool_destroy(conf->pool);
541 kfree(conf->multipaths);
542 kfree(conf);
543 mddev->private = NULL;
544 out:
545 return -EIO;
546 }
547
548
549 static int multipath_stop (mddev_t *mddev)
550 {
551 multipath_conf_t *conf = mddev_to_conf(mddev);
552
553 md_unregister_thread(mddev->thread);
554 mddev->thread = NULL;
555 blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
556 mempool_destroy(conf->pool);
557 kfree(conf->multipaths);
558 kfree(conf);
559 mddev->private = NULL;
560 return 0;
561 }
562
563 static mdk_personality_t multipath_personality=
564 {
565 .name = "multipath",
566 .owner = THIS_MODULE,
567 .make_request = multipath_make_request,
568 .run = multipath_run,
569 .stop = multipath_stop,
570 .status = multipath_status,
571 .error_handler = multipath_error,
572 .hot_add_disk = multipath_add_disk,
573 .hot_remove_disk= multipath_remove_disk,
574 };
575
576 static int __init multipath_init (void)
577 {
578 return register_md_personality (MULTIPATH, &multipath_personality);
579 }
580
581 static void __exit multipath_exit (void)
582 {
583 unregister_md_personality (MULTIPATH);
584 }
585
586 module_init(multipath_init);
587 module_exit(multipath_exit);
588 MODULE_LICENSE("GPL");
589 MODULE_ALIAS("md-personality-7"); /* MULTIPATH */
Linux with added FPC-III support