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1da177e4 LT |
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 | ||
dd0fc66f | 41 | static void *mp_pool_alloc(gfp_t gfp_flags, void *data) |
1da177e4 LT |
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 | ||
75c96f85 AB |
106 | static int multipath_end_request(struct bio *bio, unsigned int bytes_done, |
107 | int error) | |
1da177e4 LT |
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 | ||
e5dcdd80 N |
172 | if (unlikely(bio_barrier(bio))) { |
173 | bio_endio(bio, bio->bi_size, -EOPNOTSUPP); | |
174 | return 0; | |
175 | } | |
176 | ||
1da177e4 LT |
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; | |
fbd568a3 | 364 | synchronize_rcu(); |
1da177e4 LT |
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 | ||
1da177e4 LT |
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; | |
7a5febe9 N |
532 | |
533 | mddev->queue->unplug_fn = multipath_unplug; | |
534 | mddev->queue->issue_flush_fn = multipath_issue_flush; | |
535 | ||
1da177e4 LT |
536 | return 0; |
537 | ||
538 | out_free_conf: | |
539 | if (conf->pool) | |
540 | mempool_destroy(conf->pool); | |
990a8baf | 541 | kfree(conf->multipaths); |
1da177e4 LT |
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 */ |