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14#include <linux/blkdev.h>
15#include <linux/module.h>
16#include <linux/raid/md_u.h>
17#include <linux/seq_file.h>
18#include <linux/slab.h>
19#include "md.h"
20#include "md-multipath.h"
21
22#define MAX_WORK_PER_DISK 128
23
24#define NR_RESERVED_BUFS 32
25
26static int multipath_map (struct mpconf *conf)
27{
28 int i, disks = conf->raid_disks;
29
30
31
32
33
34
35 rcu_read_lock();
36 for (i = 0; i < disks; i++) {
37 struct md_rdev *rdev = rcu_dereference(conf->multipaths[i].rdev);
38 if (rdev && test_bit(In_sync, &rdev->flags) &&
39 !test_bit(Faulty, &rdev->flags)) {
40 atomic_inc(&rdev->nr_pending);
41 rcu_read_unlock();
42 return i;
43 }
44 }
45 rcu_read_unlock();
46
47 pr_crit_ratelimited("multipath_map(): no more operational IO paths?\n");
48 return (-1);
49}
50
51static void multipath_reschedule_retry (struct multipath_bh *mp_bh)
52{
53 unsigned long flags;
54 struct mddev *mddev = mp_bh->mddev;
55 struct mpconf *conf = mddev->private;
56
57 spin_lock_irqsave(&conf->device_lock, flags);
58 list_add(&mp_bh->retry_list, &conf->retry_list);
59 spin_unlock_irqrestore(&conf->device_lock, flags);
60 md_wakeup_thread(mddev->thread);
61}
62
63
64
65
66
67
68static void multipath_end_bh_io(struct multipath_bh *mp_bh, blk_status_t status)
69{
70 struct bio *bio = mp_bh->master_bio;
71 struct mpconf *conf = mp_bh->mddev->private;
72
73 bio->bi_status = status;
74 bio_endio(bio);
75 mempool_free(mp_bh, &conf->pool);
76}
77
78static void multipath_end_request(struct bio *bio)
79{
80 struct multipath_bh *mp_bh = bio->bi_private;
81 struct mpconf *conf = mp_bh->mddev->private;
82 struct md_rdev *rdev = conf->multipaths[mp_bh->path].rdev;
83
84 if (!bio->bi_status)
85 multipath_end_bh_io(mp_bh, 0);
86 else if (!(bio->bi_opf & REQ_RAHEAD)) {
87
88
89
90 char b[BDEVNAME_SIZE];
91 md_error (mp_bh->mddev, rdev);
92 pr_info("multipath: %s: rescheduling sector %llu\n",
93 bdevname(rdev->bdev,b),
94 (unsigned long long)bio->bi_iter.bi_sector);
95 multipath_reschedule_retry(mp_bh);
96 } else
97 multipath_end_bh_io(mp_bh, bio->bi_status);
98 rdev_dec_pending(rdev, conf->mddev);
99}
100
101static bool multipath_make_request(struct mddev *mddev, struct bio * bio)
102{
103 struct mpconf *conf = mddev->private;
104 struct multipath_bh * mp_bh;
105 struct multipath_info *multipath;
106
107 if (unlikely(bio->bi_opf & REQ_PREFLUSH)) {
108 md_flush_request(mddev, bio);
109 return true;
110 }
111
112 mp_bh = mempool_alloc(&conf->pool, GFP_NOIO);
113
114 mp_bh->master_bio = bio;
115 mp_bh->mddev = mddev;
116
117 mp_bh->path = multipath_map(conf);
118 if (mp_bh->path < 0) {
119 bio_io_error(bio);
120 mempool_free(mp_bh, &conf->pool);
121 return true;
122 }
123 multipath = conf->multipaths + mp_bh->path;
124
125 bio_init(&mp_bh->bio, NULL, 0);
126 __bio_clone_fast(&mp_bh->bio, bio);
127
128 mp_bh->bio.bi_iter.bi_sector += multipath->rdev->data_offset;
129 bio_set_dev(&mp_bh->bio, multipath->rdev->bdev);
130 mp_bh->bio.bi_opf |= REQ_FAILFAST_TRANSPORT;
131 mp_bh->bio.bi_end_io = multipath_end_request;
132 mp_bh->bio.bi_private = mp_bh;
133 mddev_check_writesame(mddev, &mp_bh->bio);
134 mddev_check_write_zeroes(mddev, &mp_bh->bio);
135 generic_make_request(&mp_bh->bio);
136 return true;
137}
138
139static void multipath_status(struct seq_file *seq, struct mddev *mddev)
140{
141 struct mpconf *conf = mddev->private;
142 int i;
143
144 seq_printf (seq, " [%d/%d] [", conf->raid_disks,
145 conf->raid_disks - mddev->degraded);
146 rcu_read_lock();
147 for (i = 0; i < conf->raid_disks; i++) {
148 struct md_rdev *rdev = rcu_dereference(conf->multipaths[i].rdev);
149 seq_printf (seq, "%s", rdev && test_bit(In_sync, &rdev->flags) ? "U" : "_");
150 }
151 rcu_read_unlock();
152 seq_putc(seq, ']');
153}
154
155static int multipath_congested(struct mddev *mddev, int bits)
156{
157 struct mpconf *conf = mddev->private;
158 int i, ret = 0;
159
160 rcu_read_lock();
161 for (i = 0; i < mddev->raid_disks ; i++) {
162 struct md_rdev *rdev = rcu_dereference(conf->multipaths[i].rdev);
163 if (rdev && !test_bit(Faulty, &rdev->flags)) {
164 struct request_queue *q = bdev_get_queue(rdev->bdev);
165
166 ret |= bdi_congested(q->backing_dev_info, bits);
167
168
169
170 break;
171 }
172 }
173 rcu_read_unlock();
174 return ret;
175}
176
177
178
179
180static void multipath_error (struct mddev *mddev, struct md_rdev *rdev)
181{
182 struct mpconf *conf = mddev->private;
183 char b[BDEVNAME_SIZE];
184
185 if (conf->raid_disks - mddev->degraded <= 1) {
186
187
188
189
190
191 pr_warn("multipath: only one IO path left and IO error.\n");
192
193 return;
194 }
195
196
197
198 if (test_and_clear_bit(In_sync, &rdev->flags)) {
199 unsigned long flags;
200 spin_lock_irqsave(&conf->device_lock, flags);
201 mddev->degraded++;
202 spin_unlock_irqrestore(&conf->device_lock, flags);
203 }
204 set_bit(Faulty, &rdev->flags);
205 set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
206 pr_err("multipath: IO failure on %s, disabling IO path.\n"
207 "multipath: Operation continuing on %d IO paths.\n",
208 bdevname(rdev->bdev, b),
209 conf->raid_disks - mddev->degraded);
210}
211
212static void print_multipath_conf (struct mpconf *conf)
213{
214 int i;
215 struct multipath_info *tmp;
216
217 pr_debug("MULTIPATH conf printout:\n");
218 if (!conf) {
219 pr_debug("(conf==NULL)\n");
220 return;
221 }
222 pr_debug(" --- wd:%d rd:%d\n", conf->raid_disks - conf->mddev->degraded,
223 conf->raid_disks);
224
225 for (i = 0; i < conf->raid_disks; i++) {
226 char b[BDEVNAME_SIZE];
227 tmp = conf->multipaths + i;
228 if (tmp->rdev)
229 pr_debug(" disk%d, o:%d, dev:%s\n",
230 i,!test_bit(Faulty, &tmp->rdev->flags),
231 bdevname(tmp->rdev->bdev,b));
232 }
233}
234
235static int multipath_add_disk(struct mddev *mddev, struct md_rdev *rdev)
236{
237 struct mpconf *conf = mddev->private;
238 int err = -EEXIST;
239 int path;
240 struct multipath_info *p;
241 int first = 0;
242 int last = mddev->raid_disks - 1;
243
244 if (rdev->raid_disk >= 0)
245 first = last = rdev->raid_disk;
246
247 print_multipath_conf(conf);
248
249 for (path = first; path <= last; path++)
250 if ((p=conf->multipaths+path)->rdev == NULL) {
251 disk_stack_limits(mddev->gendisk, rdev->bdev,
252 rdev->data_offset << 9);
253
254 err = md_integrity_add_rdev(rdev, mddev);
255 if (err)
256 break;
257 spin_lock_irq(&conf->device_lock);
258 mddev->degraded--;
259 rdev->raid_disk = path;
260 set_bit(In_sync, &rdev->flags);
261 spin_unlock_irq(&conf->device_lock);
262 rcu_assign_pointer(p->rdev, rdev);
263 err = 0;
264 break;
265 }
266
267 print_multipath_conf(conf);
268
269 return err;
270}
271
272static int multipath_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
273{
274 struct mpconf *conf = mddev->private;
275 int err = 0;
276 int number = rdev->raid_disk;
277 struct multipath_info *p = conf->multipaths + number;
278
279 print_multipath_conf(conf);
280
281 if (rdev == p->rdev) {
282 if (test_bit(In_sync, &rdev->flags) ||
283 atomic_read(&rdev->nr_pending)) {
284 pr_warn("hot-remove-disk, slot %d is identified but is still operational!\n", number);
285 err = -EBUSY;
286 goto abort;
287 }
288 p->rdev = NULL;
289 if (!test_bit(RemoveSynchronized, &rdev->flags)) {
290 synchronize_rcu();
291 if (atomic_read(&rdev->nr_pending)) {
292
293 err = -EBUSY;
294 p->rdev = rdev;
295 goto abort;
296 }
297 }
298 err = md_integrity_register(mddev);
299 }
300abort:
301
302 print_multipath_conf(conf);
303 return err;
304}
305
306
307
308
309
310
311
312
313
314static void multipathd(struct md_thread *thread)
315{
316 struct mddev *mddev = thread->mddev;
317 struct multipath_bh *mp_bh;
318 struct bio *bio;
319 unsigned long flags;
320 struct mpconf *conf = mddev->private;
321 struct list_head *head = &conf->retry_list;
322
323 md_check_recovery(mddev);
324 for (;;) {
325 char b[BDEVNAME_SIZE];
326 spin_lock_irqsave(&conf->device_lock, flags);
327 if (list_empty(head))
328 break;
329 mp_bh = list_entry(head->prev, struct multipath_bh, retry_list);
330 list_del(head->prev);
331 spin_unlock_irqrestore(&conf->device_lock, flags);
332
333 bio = &mp_bh->bio;
334 bio->bi_iter.bi_sector = mp_bh->master_bio->bi_iter.bi_sector;
335
336 if ((mp_bh->path = multipath_map (conf))<0) {
337 pr_err("multipath: %s: unrecoverable IO read error for block %llu\n",
338 bio_devname(bio, b),
339 (unsigned long long)bio->bi_iter.bi_sector);
340 multipath_end_bh_io(mp_bh, BLK_STS_IOERR);
341 } else {
342 pr_err("multipath: %s: redirecting sector %llu to another IO path\n",
343 bio_devname(bio, b),
344 (unsigned long long)bio->bi_iter.bi_sector);
345 *bio = *(mp_bh->master_bio);
346 bio->bi_iter.bi_sector +=
347 conf->multipaths[mp_bh->path].rdev->data_offset;
348 bio_set_dev(bio, conf->multipaths[mp_bh->path].rdev->bdev);
349 bio->bi_opf |= REQ_FAILFAST_TRANSPORT;
350 bio->bi_end_io = multipath_end_request;
351 bio->bi_private = mp_bh;
352 generic_make_request(bio);
353 }
354 }
355 spin_unlock_irqrestore(&conf->device_lock, flags);
356}
357
358static sector_t multipath_size(struct mddev *mddev, sector_t sectors, int raid_disks)
359{
360 WARN_ONCE(sectors || raid_disks,
361 "%s does not support generic reshape\n", __func__);
362
363 return mddev->dev_sectors;
364}
365
366static int multipath_run (struct mddev *mddev)
367{
368 struct mpconf *conf;
369 int disk_idx;
370 struct multipath_info *disk;
371 struct md_rdev *rdev;
372 int working_disks;
373 int ret;
374
375 if (md_check_no_bitmap(mddev))
376 return -EINVAL;
377
378 if (mddev->level != LEVEL_MULTIPATH) {
379 pr_warn("multipath: %s: raid level not set to multipath IO (%d)\n",
380 mdname(mddev), mddev->level);
381 goto out;
382 }
383
384
385
386
387
388
389 conf = kzalloc(sizeof(struct mpconf), GFP_KERNEL);
390 mddev->private = conf;
391 if (!conf)
392 goto out;
393
394 conf->multipaths = kcalloc(mddev->raid_disks,
395 sizeof(struct multipath_info),
396 GFP_KERNEL);
397 if (!conf->multipaths)
398 goto out_free_conf;
399
400 working_disks = 0;
401 rdev_for_each(rdev, mddev) {
402 disk_idx = rdev->raid_disk;
403 if (disk_idx < 0 ||
404 disk_idx >= mddev->raid_disks)
405 continue;
406
407 disk = conf->multipaths + disk_idx;
408 disk->rdev = rdev;
409 disk_stack_limits(mddev->gendisk, rdev->bdev,
410 rdev->data_offset << 9);
411
412 if (!test_bit(Faulty, &rdev->flags))
413 working_disks++;
414 }
415
416 conf->raid_disks = mddev->raid_disks;
417 conf->mddev = mddev;
418 spin_lock_init(&conf->device_lock);
419 INIT_LIST_HEAD(&conf->retry_list);
420
421 if (!working_disks) {
422 pr_warn("multipath: no operational IO paths for %s\n",
423 mdname(mddev));
424 goto out_free_conf;
425 }
426 mddev->degraded = conf->raid_disks - working_disks;
427
428 ret = mempool_init_kmalloc_pool(&conf->pool, NR_RESERVED_BUFS,
429 sizeof(struct multipath_bh));
430 if (ret)
431 goto out_free_conf;
432
433 mddev->thread = md_register_thread(multipathd, mddev,
434 "multipath");
435 if (!mddev->thread)
436 goto out_free_conf;
437
438 pr_info("multipath: array %s active with %d out of %d IO paths\n",
439 mdname(mddev), conf->raid_disks - mddev->degraded,
440 mddev->raid_disks);
441
442
443
444 md_set_array_sectors(mddev, multipath_size(mddev, 0, 0));
445
446 if (md_integrity_register(mddev))
447 goto out_free_conf;
448
449 return 0;
450
451out_free_conf:
452 mempool_exit(&conf->pool);
453 kfree(conf->multipaths);
454 kfree(conf);
455 mddev->private = NULL;
456out:
457 return -EIO;
458}
459
460static void multipath_free(struct mddev *mddev, void *priv)
461{
462 struct mpconf *conf = priv;
463
464 mempool_exit(&conf->pool);
465 kfree(conf->multipaths);
466 kfree(conf);
467}
468
469static struct md_personality multipath_personality =
470{
471 .name = "multipath",
472 .level = LEVEL_MULTIPATH,
473 .owner = THIS_MODULE,
474 .make_request = multipath_make_request,
475 .run = multipath_run,
476 .free = multipath_free,
477 .status = multipath_status,
478 .error_handler = multipath_error,
479 .hot_add_disk = multipath_add_disk,
480 .hot_remove_disk= multipath_remove_disk,
481 .size = multipath_size,
482 .congested = multipath_congested,
483};
484
485static int __init multipath_init (void)
486{
487 return register_md_personality (&multipath_personality);
488}
489
490static void __exit multipath_exit (void)
491{
492 unregister_md_personality (&multipath_personality);
493}
494
495module_init(multipath_init);
496module_exit(multipath_exit);
497MODULE_LICENSE("GPL");
498MODULE_DESCRIPTION("simple multi-path personality for MD");
499MODULE_ALIAS("md-personality-7");
500MODULE_ALIAS("md-multipath");
501MODULE_ALIAS("md-level--4");
502
