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FRV: Use generic show_interrupts()
[cris-mirror.git] / drivers / md / multipath.c
blobc35890990985632646483a97e849277023850b1a
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 int multipath_make_request(mddev_t *mddev, struct bio * bio)
110 {
111 multipath_conf_t *conf = mddev->private;
112 struct multipath_bh * mp_bh;
113 struct multipath_info *multipath;
114
115 if (unlikely(bio->bi_rw & REQ_FLUSH)) {
116 md_flush_request(mddev, bio);
117 return 0;
118 }
119
120 mp_bh = mempool_alloc(conf->pool, GFP_NOIO);
121
122 mp_bh->master_bio = bio;
123 mp_bh->mddev = mddev;
124
125 mp_bh->path = multipath_map(conf);
126 if (mp_bh->path < 0) {
127 bio_endio(bio, -EIO);
128 mempool_free(mp_bh, conf->pool);
129 return 0;
130 }
131 multipath = conf->multipaths + mp_bh->path;
132
133 mp_bh->bio = *bio;
134 mp_bh->bio.bi_sector += multipath->rdev->data_offset;
135 mp_bh->bio.bi_bdev = multipath->rdev->bdev;
136 mp_bh->bio.bi_rw |= REQ_FAILFAST_TRANSPORT;
137 mp_bh->bio.bi_end_io = multipath_end_request;
138 mp_bh->bio.bi_private = mp_bh;
139 generic_make_request(&mp_bh->bio);
140 return 0;
141 }
142
143 static void multipath_status (struct seq_file *seq, mddev_t *mddev)
144 {
145 multipath_conf_t *conf = mddev->private;
146 int i;
147
148 seq_printf (seq, " [%d/%d] [", conf->raid_disks,
149 conf->working_disks);
150 for (i = 0; i < conf->raid_disks; i++)
151 seq_printf (seq, "%s",
152 conf->multipaths[i].rdev &&
153 test_bit(In_sync, &conf->multipaths[i].rdev->flags) ? "U" : "_");
154 seq_printf (seq, "]");
155 }
156
157 static int multipath_congested(void *data, int bits)
158 {
159 mddev_t *mddev = data;
160 multipath_conf_t *conf = mddev->private;
161 int i, ret = 0;
162
163 if (mddev_congested(mddev, bits))
164 return 1;
165
166 rcu_read_lock();
167 for (i = 0; i < mddev->raid_disks ; i++) {
168 mdk_rdev_t *rdev = rcu_dereference(conf->multipaths[i].rdev);
169 if (rdev && !test_bit(Faulty, &rdev->flags)) {
170 struct request_queue *q = bdev_get_queue(rdev->bdev);
171
172 ret |= bdi_congested(&q->backing_dev_info, bits);
173 /* Just like multipath_map, we just check the
174 * first available device
175 */
176 break;
177 }
178 }
179 rcu_read_unlock();
180 return ret;
181 }
182
183 /*
184 * Careful, this can execute in IRQ contexts as well!
185 */
186 static void multipath_error (mddev_t *mddev, mdk_rdev_t *rdev)
187 {
188 multipath_conf_t *conf = mddev->private;
189
190 if (conf->working_disks <= 1) {
191 /*
192 * Uh oh, we can do nothing if this is our last path, but
193 * first check if this is a queued request for a device
194 * which has just failed.
195 */
196 printk(KERN_ALERT
197 "multipath: only one IO path left and IO error.\n");
198 /* leave it active... it's all we have */
199 } else {
200 /*
201 * Mark disk as unusable
202 */
203 if (!test_bit(Faulty, &rdev->flags)) {
204 char b[BDEVNAME_SIZE];
205 clear_bit(In_sync, &rdev->flags);
206 set_bit(Faulty, &rdev->flags);
207 set_bit(MD_CHANGE_DEVS, &mddev->flags);
208 conf->working_disks--;
209 mddev->degraded++;
210 printk(KERN_ALERT "multipath: IO failure on %s,"
211 " disabling IO path.\n"
212 "multipath: Operation continuing"
213 " on %d IO paths.\n",
214 bdevname (rdev->bdev,b),
215 conf->working_disks);
216 }
217 }
218 }
219
220 static void print_multipath_conf (multipath_conf_t *conf)
221 {
222 int i;
223 struct multipath_info *tmp;
224
225 printk("MULTIPATH conf printout:\n");
226 if (!conf) {
227 printk("(conf==NULL)\n");
228 return;
229 }
230 printk(" --- wd:%d rd:%d\n", conf->working_disks,
231 conf->raid_disks);
232
233 for (i = 0; i < conf->raid_disks; i++) {
234 char b[BDEVNAME_SIZE];
235 tmp = conf->multipaths + i;
236 if (tmp->rdev)
237 printk(" disk%d, o:%d, dev:%s\n",
238 i,!test_bit(Faulty, &tmp->rdev->flags),
239 bdevname(tmp->rdev->bdev,b));
240 }
241 }
242
243
244 static int multipath_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
245 {
246 multipath_conf_t *conf = mddev->private;
247 struct request_queue *q;
248 int err = -EEXIST;
249 int path;
250 struct multipath_info *p;
251 int first = 0;
252 int last = mddev->raid_disks - 1;
253
254 if (rdev->raid_disk >= 0)
255 first = last = rdev->raid_disk;
256
257 print_multipath_conf(conf);
258
259 for (path = first; path <= last; path++)
260 if ((p=conf->multipaths+path)->rdev == NULL) {
261 q = rdev->bdev->bd_disk->queue;
262 disk_stack_limits(mddev->gendisk, rdev->bdev,
263 rdev->data_offset << 9);
264
265 /* as we don't honour merge_bvec_fn, we must never risk
266 * violating it, so limit ->max_segments to one, lying
267 * within a single page.
268 * (Note: it is very unlikely that a device with
269 * merge_bvec_fn will be involved in multipath.)
270 */
271 if (q->merge_bvec_fn) {
272 blk_queue_max_segments(mddev->queue, 1);
273 blk_queue_segment_boundary(mddev->queue,
274 PAGE_CACHE_SIZE - 1);
275 }
276
277 conf->working_disks++;
278 mddev->degraded--;
279 rdev->raid_disk = path;
280 set_bit(In_sync, &rdev->flags);
281 rcu_assign_pointer(p->rdev, rdev);
282 err = 0;
283 md_integrity_add_rdev(rdev, mddev);
284 break;
285 }
286
287 print_multipath_conf(conf);
288
289 return err;
290 }
291
292 static int multipath_remove_disk(mddev_t *mddev, int number)
293 {
294 multipath_conf_t *conf = mddev->private;
295 int err = 0;
296 mdk_rdev_t *rdev;
297 struct multipath_info *p = conf->multipaths + number;
298
299 print_multipath_conf(conf);
300
301 rdev = p->rdev;
302 if (rdev) {
303 if (test_bit(In_sync, &rdev->flags) ||
304 atomic_read(&rdev->nr_pending)) {
305 printk(KERN_ERR "hot-remove-disk, slot %d is identified"
306 " but is still operational!\n", number);
307 err = -EBUSY;
308 goto abort;
309 }
310 p->rdev = NULL;
311 synchronize_rcu();
312 if (atomic_read(&rdev->nr_pending)) {
313 /* lost the race, try later */
314 err = -EBUSY;
315 p->rdev = rdev;
316 goto abort;
317 }
318 err = md_integrity_register(mddev);
319 }
320 abort:
321
322 print_multipath_conf(conf);
323 return err;
324 }
325
326
327
328 /*
329 * This is a kernel thread which:
330 *
331 * 1. Retries failed read operations on working multipaths.
332 * 2. Updates the raid superblock when problems encounter.
333 * 3. Performs writes following reads for array syncronising.
334 */
335
336 static void multipathd (mddev_t *mddev)
337 {
338 struct multipath_bh *mp_bh;
339 struct bio *bio;
340 unsigned long flags;
341 multipath_conf_t *conf = mddev->private;
342 struct list_head *head = &conf->retry_list;
343
344 md_check_recovery(mddev);
345 for (;;) {
346 char b[BDEVNAME_SIZE];
347 spin_lock_irqsave(&conf->device_lock, flags);
348 if (list_empty(head))
349 break;
350 mp_bh = list_entry(head->prev, struct multipath_bh, retry_list);
351 list_del(head->prev);
352 spin_unlock_irqrestore(&conf->device_lock, flags);
353
354 bio = &mp_bh->bio;
355 bio->bi_sector = mp_bh->master_bio->bi_sector;
356
357 if ((mp_bh->path = multipath_map (conf))<0) {
358 printk(KERN_ALERT "multipath: %s: unrecoverable IO read"
359 " error for block %llu\n",
360 bdevname(bio->bi_bdev,b),
361 (unsigned long long)bio->bi_sector);
362 multipath_end_bh_io(mp_bh, -EIO);
363 } else {
364 printk(KERN_ERR "multipath: %s: redirecting sector %llu"
365 " to another IO path\n",
366 bdevname(bio->bi_bdev,b),
367 (unsigned long long)bio->bi_sector);
368 *bio = *(mp_bh->master_bio);
369 bio->bi_sector += conf->multipaths[mp_bh->path].rdev->data_offset;
370 bio->bi_bdev = conf->multipaths[mp_bh->path].rdev->bdev;
371 bio->bi_rw |= REQ_FAILFAST_TRANSPORT;
372 bio->bi_end_io = multipath_end_request;
373 bio->bi_private = mp_bh;
374 generic_make_request(bio);
375 }
376 }
377 spin_unlock_irqrestore(&conf->device_lock, flags);
378 }
379
380 static sector_t multipath_size(mddev_t *mddev, sector_t sectors, int raid_disks)
381 {
382 WARN_ONCE(sectors || raid_disks,
383 "%s does not support generic reshape\n", __func__);
384
385 return mddev->dev_sectors;
386 }
387
388 static int multipath_run (mddev_t *mddev)
389 {
390 multipath_conf_t *conf;
391 int disk_idx;
392 struct multipath_info *disk;
393 mdk_rdev_t *rdev;
394
395 if (md_check_no_bitmap(mddev))
396 return -EINVAL;
397
398 if (mddev->level != LEVEL_MULTIPATH) {
399 printk("multipath: %s: raid level not set to multipath IO (%d)\n",
400 mdname(mddev), mddev->level);
401 goto out;
402 }
403 /*
404 * copy the already verified devices into our private MULTIPATH
405 * bookkeeping area. [whatever we allocate in multipath_run(),
406 * should be freed in multipath_stop()]
407 */
408
409 conf = kzalloc(sizeof(multipath_conf_t), GFP_KERNEL);
410 mddev->private = conf;
411 if (!conf) {
412 printk(KERN_ERR
413 "multipath: couldn't allocate memory for %s\n",
414 mdname(mddev));
415 goto out;
416 }
417
418 conf->multipaths = kzalloc(sizeof(struct multipath_info)*mddev->raid_disks,
419 GFP_KERNEL);
420 if (!conf->multipaths) {
421 printk(KERN_ERR
422 "multipath: couldn't allocate memory for %s\n",
423 mdname(mddev));
424 goto out_free_conf;
425 }
426
427 conf->working_disks = 0;
428 list_for_each_entry(rdev, &mddev->disks, same_set) {
429 disk_idx = rdev->raid_disk;
430 if (disk_idx < 0 ||
431 disk_idx >= mddev->raid_disks)
432 continue;
433
434 disk = conf->multipaths + disk_idx;
435 disk->rdev = rdev;
436 disk_stack_limits(mddev->gendisk, rdev->bdev,
437 rdev->data_offset << 9);
438
439 /* as we don't honour merge_bvec_fn, we must never risk
440 * violating it, not that we ever expect a device with
441 * a merge_bvec_fn to be involved in multipath */
442 if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
443 blk_queue_max_segments(mddev->queue, 1);
444 blk_queue_segment_boundary(mddev->queue,
445 PAGE_CACHE_SIZE - 1);
446 }
447
448 if (!test_bit(Faulty, &rdev->flags))
449 conf->working_disks++;
450 }
451
452 conf->raid_disks = mddev->raid_disks;
453 conf->mddev = mddev;
454 spin_lock_init(&conf->device_lock);
455 INIT_LIST_HEAD(&conf->retry_list);
456
457 if (!conf->working_disks) {
458 printk(KERN_ERR "multipath: no operational IO paths for %s\n",
459 mdname(mddev));
460 goto out_free_conf;
461 }
462 mddev->degraded = conf->raid_disks - conf->working_disks;
463
464 conf->pool = mempool_create_kmalloc_pool(NR_RESERVED_BUFS,
465 sizeof(struct multipath_bh));
466 if (conf->pool == NULL) {
467 printk(KERN_ERR
468 "multipath: couldn't allocate memory for %s\n",
469 mdname(mddev));
470 goto out_free_conf;
471 }
472
473 {
474 mddev->thread = md_register_thread(multipathd, mddev, NULL);
475 if (!mddev->thread) {
476 printk(KERN_ERR "multipath: couldn't allocate thread"
477 " for %s\n", mdname(mddev));
478 goto out_free_conf;
479 }
480 }
481
482 printk(KERN_INFO
483 "multipath: array %s active with %d out of %d IO paths\n",
484 mdname(mddev), conf->working_disks, mddev->raid_disks);
485 /*
486 * Ok, everything is just fine now
487 */
488 md_set_array_sectors(mddev, multipath_size(mddev, 0, 0));
489
490 mddev->queue->backing_dev_info.congested_fn = multipath_congested;
491 mddev->queue->backing_dev_info.congested_data = mddev;
492
493 if (md_integrity_register(mddev))
494 goto out_free_conf;
495
496 return 0;
497
498 out_free_conf:
499 if (conf->pool)
500 mempool_destroy(conf->pool);
501 kfree(conf->multipaths);
502 kfree(conf);
503 mddev->private = NULL;
504 out:
505 return -EIO;
506 }
507
508
509 static int multipath_stop (mddev_t *mddev)
510 {
511 multipath_conf_t *conf = mddev->private;
512
513 md_unregister_thread(mddev->thread);
514 mddev->thread = NULL;
515 blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
516 mempool_destroy(conf->pool);
517 kfree(conf->multipaths);
518 kfree(conf);
519 mddev->private = NULL;
520 return 0;
521 }
522
523 static struct mdk_personality multipath_personality =
524 {
525 .name = "multipath",
526 .level = LEVEL_MULTIPATH,
527 .owner = THIS_MODULE,
528 .make_request = multipath_make_request,
529 .run = multipath_run,
530 .stop = multipath_stop,
531 .status = multipath_status,
532 .error_handler = multipath_error,
533 .hot_add_disk = multipath_add_disk,
534 .hot_remove_disk= multipath_remove_disk,
535 .size = multipath_size,
536 };
537
538 static int __init multipath_init (void)
539 {
540 return register_md_personality (&multipath_personality);
541 }
542
543 static void __exit multipath_exit (void)
544 {
545 unregister_md_personality (&multipath_personality);
546 }
547
548 module_init(multipath_init);
549 module_exit(multipath_exit);
550 MODULE_LICENSE("GPL");
551 MODULE_DESCRIPTION("simple multi-path personality for MD");
552 MODULE_ALIAS("md-personality-7"); /* MULTIPATH */
553 MODULE_ALIAS("md-multipath");
554 MODULE_ALIAS("md-level--4");
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