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