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22#include <linux/blkdev.h>
23#include <linux/module.h>
24#include <linux/raid/md_u.h>
25#include <linux/seq_file.h>
26#include <linux/slab.h>
27#include "md.h"
28#include "multipath.h"
29
30#define MAX_WORK_PER_DISK 128
31
32#define NR_RESERVED_BUFS 32
33
34static int multipath_map (struct mpconf *conf)
35{
36 int i, disks = conf->raid_disks;
37
38
39
40
41
42
43 rcu_read_lock();
44 for (i = 0; i < disks; i++) {
45 struct md_rdev *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
58static void multipath_reschedule_retry (struct multipath_bh *mp_bh)
59{
60 unsigned long flags;
61 struct mddev *mddev = mp_bh->mddev;
62 struct mpconf *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
73
74
75static void multipath_end_bh_io (struct multipath_bh *mp_bh, int err)
76{
77 struct bio *bio = mp_bh->master_bio;
78 struct mpconf *conf = mp_bh->mddev->private;
79
80 bio_endio(bio, err);
81 mempool_free(mp_bh, conf->pool);
82}
83
84static void multipath_end_request(struct bio *bio, int error)
85{
86 int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
87 struct multipath_bh *mp_bh = bio->bi_private;
88 struct mpconf *conf = mp_bh->mddev->private;
89 struct md_rdev *rdev = conf->multipaths[mp_bh->path].rdev;
90
91 if (uptodate)
92 multipath_end_bh_io(mp_bh, 0);
93 else if (!(bio->bi_rw & REQ_RAHEAD)) {
94
95
96
97 char b[BDEVNAME_SIZE];
98 md_error (mp_bh->mddev, rdev);
99 printk(KERN_ERR "multipath: %s: rescheduling sector %llu\n",
100 bdevname(rdev->bdev,b),
101 (unsigned long long)bio->bi_iter.bi_sector);
102 multipath_reschedule_retry(mp_bh);
103 } else
104 multipath_end_bh_io(mp_bh, error);
105 rdev_dec_pending(rdev, conf->mddev);
106}
107
108static void multipath_make_request(struct mddev *mddev, struct bio * bio)
109{
110 struct mpconf *conf = mddev->private;
111 struct multipath_bh * mp_bh;
112 struct multipath_info *multipath;
113
114 if (unlikely(bio->bi_rw & REQ_FLUSH)) {
115 md_flush_request(mddev, bio);
116 return;
117 }
118
119 mp_bh = mempool_alloc(conf->pool, GFP_NOIO);
120
121 mp_bh->master_bio = bio;
122 mp_bh->mddev = mddev;
123
124 mp_bh->path = multipath_map(conf);
125 if (mp_bh->path < 0) {
126 bio_endio(bio, -EIO);
127 mempool_free(mp_bh, conf->pool);
128 return;
129 }
130 multipath = conf->multipaths + mp_bh->path;
131
132 mp_bh->bio = *bio;
133 mp_bh->bio.bi_iter.bi_sector += multipath->rdev->data_offset;
134 mp_bh->bio.bi_bdev = multipath->rdev->bdev;
135 mp_bh->bio.bi_rw |= REQ_FAILFAST_TRANSPORT;
136 mp_bh->bio.bi_end_io = multipath_end_request;
137 mp_bh->bio.bi_private = mp_bh;
138 generic_make_request(&mp_bh->bio);
139 return;
140}
141
142static void multipath_status (struct seq_file *seq, struct mddev *mddev)
143{
144 struct mpconf *conf = mddev->private;
145 int i;
146
147 seq_printf (seq, " [%d/%d] [", conf->raid_disks,
148 conf->raid_disks - mddev->degraded);
149 for (i = 0; i < conf->raid_disks; i++)
150 seq_printf (seq, "%s",
151 conf->multipaths[i].rdev &&
152 test_bit(In_sync, &conf->multipaths[i].rdev->flags) ? "U" : "_");
153 seq_printf (seq, "]");
154}
155
156static int multipath_congested(void *data, int bits)
157{
158 struct mddev *mddev = data;
159 struct mpconf *conf = mddev->private;
160 int i, ret = 0;
161
162 if (mddev_congested(mddev, bits))
163 return 1;
164
165 rcu_read_lock();
166 for (i = 0; i < mddev->raid_disks ; i++) {
167 struct md_rdev *rdev = rcu_dereference(conf->multipaths[i].rdev);
168 if (rdev && !test_bit(Faulty, &rdev->flags)) {
169 struct request_queue *q = bdev_get_queue(rdev->bdev);
170
171 ret |= bdi_congested(&q->backing_dev_info, bits);
172
173
174
175 break;
176 }
177 }
178 rcu_read_unlock();
179 return ret;
180}
181
182
183
184
185static void multipath_error (struct mddev *mddev, struct md_rdev *rdev)
186{
187 struct mpconf *conf = mddev->private;
188 char b[BDEVNAME_SIZE];
189
190 if (conf->raid_disks - mddev->degraded <= 1) {
191
192
193
194
195
196 printk(KERN_ALERT
197 "multipath: only one IO path left and IO error.\n");
198
199 return;
200 }
201
202
203
204 if (test_and_clear_bit(In_sync, &rdev->flags)) {
205 unsigned long flags;
206 spin_lock_irqsave(&conf->device_lock, flags);
207 mddev->degraded++;
208 spin_unlock_irqrestore(&conf->device_lock, flags);
209 }
210 set_bit(Faulty, &rdev->flags);
211 set_bit(MD_CHANGE_DEVS, &mddev->flags);
212 printk(KERN_ALERT "multipath: IO failure on %s,"
213 " disabling IO path.\n"
214 "multipath: Operation continuing"
215 " on %d IO paths.\n",
216 bdevname(rdev->bdev, b),
217 conf->raid_disks - mddev->degraded);
218}
219
220static void print_multipath_conf (struct mpconf *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->raid_disks - conf->mddev->degraded,
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
243static int multipath_add_disk(struct mddev *mddev, struct md_rdev *rdev)
244{
245 struct mpconf *conf = mddev->private;
246 struct request_queue *q;
247 int err = -EEXIST;
248 int path;
249 struct multipath_info *p;
250 int first = 0;
251 int last = mddev->raid_disks - 1;
252
253 if (rdev->raid_disk >= 0)
254 first = last = rdev->raid_disk;
255
256 print_multipath_conf(conf);
257
258 for (path = first; path <= last; path++)
259 if ((p=conf->multipaths+path)->rdev == NULL) {
260 q = rdev->bdev->bd_disk->queue;
261 disk_stack_limits(mddev->gendisk, rdev->bdev,
262 rdev->data_offset << 9);
263
264
265
266
267
268
269
270 if (q->merge_bvec_fn) {
271 blk_queue_max_segments(mddev->queue, 1);
272 blk_queue_segment_boundary(mddev->queue,
273 PAGE_CACHE_SIZE - 1);
274 }
275
276 spin_lock_irq(&conf->device_lock);
277 mddev->degraded--;
278 rdev->raid_disk = path;
279 set_bit(In_sync, &rdev->flags);
280 spin_unlock_irq(&conf->device_lock);
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
292static int multipath_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
293{
294 struct mpconf *conf = mddev->private;
295 int err = 0;
296 int number = rdev->raid_disk;
297 struct multipath_info *p = conf->multipaths + number;
298
299 print_multipath_conf(conf);
300
301 if (rdev == p->rdev) {
302 if (test_bit(In_sync, &rdev->flags) ||
303 atomic_read(&rdev->nr_pending)) {
304 printk(KERN_ERR "hot-remove-disk, slot %d is identified"
305 " but is still operational!\n", number);
306 err = -EBUSY;
307 goto abort;
308 }
309 p->rdev = NULL;
310 synchronize_rcu();
311 if (atomic_read(&rdev->nr_pending)) {
312
313 err = -EBUSY;
314 p->rdev = rdev;
315 goto abort;
316 }
317 err = md_integrity_register(mddev);
318 }
319abort:
320
321 print_multipath_conf(conf);
322 return err;
323}
324
325
326
327
328
329
330
331
332
333static void multipathd(struct md_thread *thread)
334{
335 struct mddev *mddev = thread->mddev;
336 struct multipath_bh *mp_bh;
337 struct bio *bio;
338 unsigned long flags;
339 struct mpconf *conf = mddev->private;
340 struct list_head *head = &conf->retry_list;
341
342 md_check_recovery(mddev);
343 for (;;) {
344 char b[BDEVNAME_SIZE];
345 spin_lock_irqsave(&conf->device_lock, flags);
346 if (list_empty(head))
347 break;
348 mp_bh = list_entry(head->prev, struct multipath_bh, retry_list);
349 list_del(head->prev);
350 spin_unlock_irqrestore(&conf->device_lock, flags);
351
352 bio = &mp_bh->bio;
353 bio->bi_iter.bi_sector = mp_bh->master_bio->bi_iter.bi_sector;
354
355 if ((mp_bh->path = multipath_map (conf))<0) {
356 printk(KERN_ALERT "multipath: %s: unrecoverable IO read"
357 " error for block %llu\n",
358 bdevname(bio->bi_bdev,b),
359 (unsigned long long)bio->bi_iter.bi_sector);
360 multipath_end_bh_io(mp_bh, -EIO);
361 } else {
362 printk(KERN_ERR "multipath: %s: redirecting sector %llu"
363 " to another IO path\n",
364 bdevname(bio->bi_bdev,b),
365 (unsigned long long)bio->bi_iter.bi_sector);
366 *bio = *(mp_bh->master_bio);
367 bio->bi_iter.bi_sector +=
368 conf->multipaths[mp_bh->path].rdev->data_offset;
369 bio->bi_bdev = conf->multipaths[mp_bh->path].rdev->bdev;
370 bio->bi_rw |= REQ_FAILFAST_TRANSPORT;
371 bio->bi_end_io = multipath_end_request;
372 bio->bi_private = mp_bh;
373 generic_make_request(bio);
374 }
375 }
376 spin_unlock_irqrestore(&conf->device_lock, flags);
377}
378
379static sector_t multipath_size(struct mddev *mddev, sector_t sectors, int raid_disks)
380{
381 WARN_ONCE(sectors || raid_disks,
382 "%s does not support generic reshape\n", __func__);
383
384 return mddev->dev_sectors;
385}
386
387static int multipath_run (struct mddev *mddev)
388{
389 struct mpconf *conf;
390 int disk_idx;
391 struct multipath_info *disk;
392 struct md_rdev *rdev;
393 int working_disks;
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
405
406
407
408
409 conf = kzalloc(sizeof(struct mpconf), 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 working_disks = 0;
428 rdev_for_each(rdev, mddev) {
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
440
441
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 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 (!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 - 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,
475 "multipath");
476 if (!mddev->thread) {
477 printk(KERN_ERR "multipath: couldn't allocate thread"
478 " for %s\n", mdname(mddev));
479 goto out_free_conf;
480 }
481 }
482
483 printk(KERN_INFO
484 "multipath: array %s active with %d out of %d IO paths\n",
485 mdname(mddev), conf->raid_disks - mddev->degraded,
486 mddev->raid_disks);
487
488
489
490 md_set_array_sectors(mddev, multipath_size(mddev, 0, 0));
491
492 mddev->queue->backing_dev_info.congested_fn = multipath_congested;
493 mddev->queue->backing_dev_info.congested_data = mddev;
494
495 if (md_integrity_register(mddev))
496 goto out_free_conf;
497
498 return 0;
499
500out_free_conf:
501 if (conf->pool)
502 mempool_destroy(conf->pool);
503 kfree(conf->multipaths);
504 kfree(conf);
505 mddev->private = NULL;
506out:
507 return -EIO;
508}
509
510static int multipath_stop (struct mddev *mddev)
511{
512 struct mpconf *conf = mddev->private;
513
514 md_unregister_thread(&mddev->thread);
515 blk_sync_queue(mddev->queue);
516 mempool_destroy(conf->pool);
517 kfree(conf->multipaths);
518 kfree(conf);
519 mddev->private = NULL;
520 return 0;
521}
522
523static struct md_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
538static int __init multipath_init (void)
539{
540 return register_md_personality (&multipath_personality);
541}
542
543static void __exit multipath_exit (void)
544{
545 unregister_md_personality (&multipath_personality);
546}
547
548module_init(multipath_init);
549module_exit(multipath_exit);
550MODULE_LICENSE("GPL");
551MODULE_DESCRIPTION("simple multi-path personality for MD");
552MODULE_ALIAS("md-personality-7");
553MODULE_ALIAS("md-multipath");
554MODULE_ALIAS("md-level--4");
555