Loading...
1/*
2 * Copyright (C) 2006-2009 Red Hat, Inc.
3 *
4 * This file is released under the LGPL.
5 */
6
7#include <linux/bio.h>
8#include <linux/slab.h>
9#include <linux/dm-dirty-log.h>
10#include <linux/device-mapper.h>
11#include <linux/dm-log-userspace.h>
12
13#include "dm-log-userspace-transfer.h"
14
15#define DM_LOG_USERSPACE_VSN "1.1.0"
16
17struct flush_entry {
18 int type;
19 region_t region;
20 struct list_head list;
21};
22
23/*
24 * This limit on the number of mark and clear request is, to a degree,
25 * arbitrary. However, there is some basis for the choice in the limits
26 * imposed on the size of data payload by dm-log-userspace-transfer.c:
27 * dm_consult_userspace().
28 */
29#define MAX_FLUSH_GROUP_COUNT 32
30
31struct log_c {
32 struct dm_target *ti;
33 uint32_t region_size;
34 region_t region_count;
35 uint64_t luid;
36 char uuid[DM_UUID_LEN];
37
38 char *usr_argv_str;
39 uint32_t usr_argc;
40
41 /*
42 * in_sync_hint gets set when doing is_remote_recovering. It
43 * represents the first region that needs recovery. IOW, the
44 * first zero bit of sync_bits. This can be useful for to limit
45 * traffic for calls like is_remote_recovering and get_resync_work,
46 * but be take care in its use for anything else.
47 */
48 uint64_t in_sync_hint;
49
50 /*
51 * Mark and clear requests are held until a flush is issued
52 * so that we can group, and thereby limit, the amount of
53 * network traffic between kernel and userspace. The 'flush_lock'
54 * is used to protect these lists.
55 */
56 spinlock_t flush_lock;
57 struct list_head mark_list;
58 struct list_head clear_list;
59};
60
61static mempool_t *flush_entry_pool;
62
63static void *flush_entry_alloc(gfp_t gfp_mask, void *pool_data)
64{
65 return kmalloc(sizeof(struct flush_entry), gfp_mask);
66}
67
68static void flush_entry_free(void *element, void *pool_data)
69{
70 kfree(element);
71}
72
73static int userspace_do_request(struct log_c *lc, const char *uuid,
74 int request_type, char *data, size_t data_size,
75 char *rdata, size_t *rdata_size)
76{
77 int r;
78
79 /*
80 * If the server isn't there, -ESRCH is returned,
81 * and we must keep trying until the server is
82 * restored.
83 */
84retry:
85 r = dm_consult_userspace(uuid, lc->luid, request_type, data,
86 data_size, rdata, rdata_size);
87
88 if (r != -ESRCH)
89 return r;
90
91 DMERR(" Userspace log server not found.");
92 while (1) {
93 set_current_state(TASK_INTERRUPTIBLE);
94 schedule_timeout(2*HZ);
95 DMWARN("Attempting to contact userspace log server...");
96 r = dm_consult_userspace(uuid, lc->luid, DM_ULOG_CTR,
97 lc->usr_argv_str,
98 strlen(lc->usr_argv_str) + 1,
99 NULL, NULL);
100 if (!r)
101 break;
102 }
103 DMINFO("Reconnected to userspace log server... DM_ULOG_CTR complete");
104 r = dm_consult_userspace(uuid, lc->luid, DM_ULOG_RESUME, NULL,
105 0, NULL, NULL);
106 if (!r)
107 goto retry;
108
109 DMERR("Error trying to resume userspace log: %d", r);
110
111 return -ESRCH;
112}
113
114static int build_constructor_string(struct dm_target *ti,
115 unsigned argc, char **argv,
116 char **ctr_str)
117{
118 int i, str_size;
119 char *str = NULL;
120
121 *ctr_str = NULL;
122
123 for (i = 0, str_size = 0; i < argc; i++)
124 str_size += strlen(argv[i]) + 1; /* +1 for space between args */
125
126 str_size += 20; /* Max number of chars in a printed u64 number */
127
128 str = kzalloc(str_size, GFP_KERNEL);
129 if (!str) {
130 DMWARN("Unable to allocate memory for constructor string");
131 return -ENOMEM;
132 }
133
134 str_size = sprintf(str, "%llu", (unsigned long long)ti->len);
135 for (i = 0; i < argc; i++)
136 str_size += sprintf(str + str_size, " %s", argv[i]);
137
138 *ctr_str = str;
139 return str_size;
140}
141
142/*
143 * userspace_ctr
144 *
145 * argv contains:
146 * <UUID> <other args>
147 * Where 'other args' is the userspace implementation specific log
148 * arguments. An example might be:
149 * <UUID> clustered_disk <arg count> <log dev> <region_size> [[no]sync]
150 *
151 * So, this module will strip off the <UUID> for identification purposes
152 * when communicating with userspace about a log; but will pass on everything
153 * else.
154 */
155static int userspace_ctr(struct dm_dirty_log *log, struct dm_target *ti,
156 unsigned argc, char **argv)
157{
158 int r = 0;
159 int str_size;
160 char *ctr_str = NULL;
161 struct log_c *lc = NULL;
162 uint64_t rdata;
163 size_t rdata_size = sizeof(rdata);
164
165 if (argc < 3) {
166 DMWARN("Too few arguments to userspace dirty log");
167 return -EINVAL;
168 }
169
170 lc = kmalloc(sizeof(*lc), GFP_KERNEL);
171 if (!lc) {
172 DMWARN("Unable to allocate userspace log context.");
173 return -ENOMEM;
174 }
175
176 /* The ptr value is sufficient for local unique id */
177 lc->luid = (unsigned long)lc;
178
179 lc->ti = ti;
180
181 if (strlen(argv[0]) > (DM_UUID_LEN - 1)) {
182 DMWARN("UUID argument too long.");
183 kfree(lc);
184 return -EINVAL;
185 }
186
187 strncpy(lc->uuid, argv[0], DM_UUID_LEN);
188 spin_lock_init(&lc->flush_lock);
189 INIT_LIST_HEAD(&lc->mark_list);
190 INIT_LIST_HEAD(&lc->clear_list);
191
192 str_size = build_constructor_string(ti, argc - 1, argv + 1, &ctr_str);
193 if (str_size < 0) {
194 kfree(lc);
195 return str_size;
196 }
197
198 /* Send table string */
199 r = dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_CTR,
200 ctr_str, str_size, NULL, NULL);
201
202 if (r < 0) {
203 if (r == -ESRCH)
204 DMERR("Userspace log server not found");
205 else
206 DMERR("Userspace log server failed to create log");
207 goto out;
208 }
209
210 /* Since the region size does not change, get it now */
211 rdata_size = sizeof(rdata);
212 r = dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_GET_REGION_SIZE,
213 NULL, 0, (char *)&rdata, &rdata_size);
214
215 if (r) {
216 DMERR("Failed to get region size of dirty log");
217 goto out;
218 }
219
220 lc->region_size = (uint32_t)rdata;
221 lc->region_count = dm_sector_div_up(ti->len, lc->region_size);
222
223out:
224 if (r) {
225 kfree(lc);
226 kfree(ctr_str);
227 } else {
228 lc->usr_argv_str = ctr_str;
229 lc->usr_argc = argc;
230 log->context = lc;
231 }
232
233 return r;
234}
235
236static void userspace_dtr(struct dm_dirty_log *log)
237{
238 struct log_c *lc = log->context;
239
240 (void) dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_DTR,
241 NULL, 0,
242 NULL, NULL);
243
244 kfree(lc->usr_argv_str);
245 kfree(lc);
246
247 return;
248}
249
250static int userspace_presuspend(struct dm_dirty_log *log)
251{
252 int r;
253 struct log_c *lc = log->context;
254
255 r = dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_PRESUSPEND,
256 NULL, 0,
257 NULL, NULL);
258
259 return r;
260}
261
262static int userspace_postsuspend(struct dm_dirty_log *log)
263{
264 int r;
265 struct log_c *lc = log->context;
266
267 r = dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_POSTSUSPEND,
268 NULL, 0,
269 NULL, NULL);
270
271 return r;
272}
273
274static int userspace_resume(struct dm_dirty_log *log)
275{
276 int r;
277 struct log_c *lc = log->context;
278
279 lc->in_sync_hint = 0;
280 r = dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_RESUME,
281 NULL, 0,
282 NULL, NULL);
283
284 return r;
285}
286
287static uint32_t userspace_get_region_size(struct dm_dirty_log *log)
288{
289 struct log_c *lc = log->context;
290
291 return lc->region_size;
292}
293
294/*
295 * userspace_is_clean
296 *
297 * Check whether a region is clean. If there is any sort of
298 * failure when consulting the server, we return not clean.
299 *
300 * Returns: 1 if clean, 0 otherwise
301 */
302static int userspace_is_clean(struct dm_dirty_log *log, region_t region)
303{
304 int r;
305 uint64_t region64 = (uint64_t)region;
306 int64_t is_clean;
307 size_t rdata_size;
308 struct log_c *lc = log->context;
309
310 rdata_size = sizeof(is_clean);
311 r = userspace_do_request(lc, lc->uuid, DM_ULOG_IS_CLEAN,
312 (char *)®ion64, sizeof(region64),
313 (char *)&is_clean, &rdata_size);
314
315 return (r) ? 0 : (int)is_clean;
316}
317
318/*
319 * userspace_in_sync
320 *
321 * Check if the region is in-sync. If there is any sort
322 * of failure when consulting the server, we assume that
323 * the region is not in sync.
324 *
325 * If 'can_block' is set, return immediately
326 *
327 * Returns: 1 if in-sync, 0 if not-in-sync, -EWOULDBLOCK
328 */
329static int userspace_in_sync(struct dm_dirty_log *log, region_t region,
330 int can_block)
331{
332 int r;
333 uint64_t region64 = region;
334 int64_t in_sync;
335 size_t rdata_size;
336 struct log_c *lc = log->context;
337
338 /*
339 * We can never respond directly - even if in_sync_hint is
340 * set. This is because another machine could see a device
341 * failure and mark the region out-of-sync. If we don't go
342 * to userspace to ask, we might think the region is in-sync
343 * and allow a read to pick up data that is stale. (This is
344 * very unlikely if a device actually fails; but it is very
345 * likely if a connection to one device from one machine fails.)
346 *
347 * There still might be a problem if the mirror caches the region
348 * state as in-sync... but then this call would not be made. So,
349 * that is a mirror problem.
350 */
351 if (!can_block)
352 return -EWOULDBLOCK;
353
354 rdata_size = sizeof(in_sync);
355 r = userspace_do_request(lc, lc->uuid, DM_ULOG_IN_SYNC,
356 (char *)®ion64, sizeof(region64),
357 (char *)&in_sync, &rdata_size);
358 return (r) ? 0 : (int)in_sync;
359}
360
361static int flush_one_by_one(struct log_c *lc, struct list_head *flush_list)
362{
363 int r = 0;
364 struct flush_entry *fe;
365
366 list_for_each_entry(fe, flush_list, list) {
367 r = userspace_do_request(lc, lc->uuid, fe->type,
368 (char *)&fe->region,
369 sizeof(fe->region),
370 NULL, NULL);
371 if (r)
372 break;
373 }
374
375 return r;
376}
377
378static int flush_by_group(struct log_c *lc, struct list_head *flush_list)
379{
380 int r = 0;
381 int count;
382 uint32_t type = 0;
383 struct flush_entry *fe, *tmp_fe;
384 LIST_HEAD(tmp_list);
385 uint64_t group[MAX_FLUSH_GROUP_COUNT];
386
387 /*
388 * Group process the requests
389 */
390 while (!list_empty(flush_list)) {
391 count = 0;
392
393 list_for_each_entry_safe(fe, tmp_fe, flush_list, list) {
394 group[count] = fe->region;
395 count++;
396
397 list_move(&fe->list, &tmp_list);
398
399 type = fe->type;
400 if (count >= MAX_FLUSH_GROUP_COUNT)
401 break;
402 }
403
404 r = userspace_do_request(lc, lc->uuid, type,
405 (char *)(group),
406 count * sizeof(uint64_t),
407 NULL, NULL);
408 if (r) {
409 /* Group send failed. Attempt one-by-one. */
410 list_splice_init(&tmp_list, flush_list);
411 r = flush_one_by_one(lc, flush_list);
412 break;
413 }
414 }
415
416 /*
417 * Must collect flush_entrys that were successfully processed
418 * as a group so that they will be free'd by the caller.
419 */
420 list_splice_init(&tmp_list, flush_list);
421
422 return r;
423}
424
425/*
426 * userspace_flush
427 *
428 * This function is ok to block.
429 * The flush happens in two stages. First, it sends all
430 * clear/mark requests that are on the list. Then it
431 * tells the server to commit them. This gives the
432 * server a chance to optimise the commit, instead of
433 * doing it for every request.
434 *
435 * Additionally, we could implement another thread that
436 * sends the requests up to the server - reducing the
437 * load on flush. Then the flush would have less in
438 * the list and be responsible for the finishing commit.
439 *
440 * Returns: 0 on success, < 0 on failure
441 */
442static int userspace_flush(struct dm_dirty_log *log)
443{
444 int r = 0;
445 unsigned long flags;
446 struct log_c *lc = log->context;
447 LIST_HEAD(mark_list);
448 LIST_HEAD(clear_list);
449 struct flush_entry *fe, *tmp_fe;
450
451 spin_lock_irqsave(&lc->flush_lock, flags);
452 list_splice_init(&lc->mark_list, &mark_list);
453 list_splice_init(&lc->clear_list, &clear_list);
454 spin_unlock_irqrestore(&lc->flush_lock, flags);
455
456 if (list_empty(&mark_list) && list_empty(&clear_list))
457 return 0;
458
459 r = flush_by_group(lc, &mark_list);
460 if (r)
461 goto fail;
462
463 r = flush_by_group(lc, &clear_list);
464 if (r)
465 goto fail;
466
467 r = userspace_do_request(lc, lc->uuid, DM_ULOG_FLUSH,
468 NULL, 0, NULL, NULL);
469
470fail:
471 /*
472 * We can safely remove these entries, even if failure.
473 * Calling code will receive an error and will know that
474 * the log facility has failed.
475 */
476 list_for_each_entry_safe(fe, tmp_fe, &mark_list, list) {
477 list_del(&fe->list);
478 mempool_free(fe, flush_entry_pool);
479 }
480 list_for_each_entry_safe(fe, tmp_fe, &clear_list, list) {
481 list_del(&fe->list);
482 mempool_free(fe, flush_entry_pool);
483 }
484
485 if (r)
486 dm_table_event(lc->ti->table);
487
488 return r;
489}
490
491/*
492 * userspace_mark_region
493 *
494 * This function should avoid blocking unless absolutely required.
495 * (Memory allocation is valid for blocking.)
496 */
497static void userspace_mark_region(struct dm_dirty_log *log, region_t region)
498{
499 unsigned long flags;
500 struct log_c *lc = log->context;
501 struct flush_entry *fe;
502
503 /* Wait for an allocation, but _never_ fail */
504 fe = mempool_alloc(flush_entry_pool, GFP_NOIO);
505 BUG_ON(!fe);
506
507 spin_lock_irqsave(&lc->flush_lock, flags);
508 fe->type = DM_ULOG_MARK_REGION;
509 fe->region = region;
510 list_add(&fe->list, &lc->mark_list);
511 spin_unlock_irqrestore(&lc->flush_lock, flags);
512
513 return;
514}
515
516/*
517 * userspace_clear_region
518 *
519 * This function must not block.
520 * So, the alloc can't block. In the worst case, it is ok to
521 * fail. It would simply mean we can't clear the region.
522 * Does nothing to current sync context, but does mean
523 * the region will be re-sync'ed on a reload of the mirror
524 * even though it is in-sync.
525 */
526static void userspace_clear_region(struct dm_dirty_log *log, region_t region)
527{
528 unsigned long flags;
529 struct log_c *lc = log->context;
530 struct flush_entry *fe;
531
532 /*
533 * If we fail to allocate, we skip the clearing of
534 * the region. This doesn't hurt us in any way, except
535 * to cause the region to be resync'ed when the
536 * device is activated next time.
537 */
538 fe = mempool_alloc(flush_entry_pool, GFP_ATOMIC);
539 if (!fe) {
540 DMERR("Failed to allocate memory to clear region.");
541 return;
542 }
543
544 spin_lock_irqsave(&lc->flush_lock, flags);
545 fe->type = DM_ULOG_CLEAR_REGION;
546 fe->region = region;
547 list_add(&fe->list, &lc->clear_list);
548 spin_unlock_irqrestore(&lc->flush_lock, flags);
549
550 return;
551}
552
553/*
554 * userspace_get_resync_work
555 *
556 * Get a region that needs recovery. It is valid to return
557 * an error for this function.
558 *
559 * Returns: 1 if region filled, 0 if no work, <0 on error
560 */
561static int userspace_get_resync_work(struct dm_dirty_log *log, region_t *region)
562{
563 int r;
564 size_t rdata_size;
565 struct log_c *lc = log->context;
566 struct {
567 int64_t i; /* 64-bit for mix arch compatibility */
568 region_t r;
569 } pkg;
570
571 if (lc->in_sync_hint >= lc->region_count)
572 return 0;
573
574 rdata_size = sizeof(pkg);
575 r = userspace_do_request(lc, lc->uuid, DM_ULOG_GET_RESYNC_WORK,
576 NULL, 0,
577 (char *)&pkg, &rdata_size);
578
579 *region = pkg.r;
580 return (r) ? r : (int)pkg.i;
581}
582
583/*
584 * userspace_set_region_sync
585 *
586 * Set the sync status of a given region. This function
587 * must not fail.
588 */
589static void userspace_set_region_sync(struct dm_dirty_log *log,
590 region_t region, int in_sync)
591{
592 int r;
593 struct log_c *lc = log->context;
594 struct {
595 region_t r;
596 int64_t i;
597 } pkg;
598
599 pkg.r = region;
600 pkg.i = (int64_t)in_sync;
601
602 r = userspace_do_request(lc, lc->uuid, DM_ULOG_SET_REGION_SYNC,
603 (char *)&pkg, sizeof(pkg),
604 NULL, NULL);
605
606 /*
607 * It would be nice to be able to report failures.
608 * However, it is easy emough to detect and resolve.
609 */
610 return;
611}
612
613/*
614 * userspace_get_sync_count
615 *
616 * If there is any sort of failure when consulting the server,
617 * we assume that the sync count is zero.
618 *
619 * Returns: sync count on success, 0 on failure
620 */
621static region_t userspace_get_sync_count(struct dm_dirty_log *log)
622{
623 int r;
624 size_t rdata_size;
625 uint64_t sync_count;
626 struct log_c *lc = log->context;
627
628 rdata_size = sizeof(sync_count);
629 r = userspace_do_request(lc, lc->uuid, DM_ULOG_GET_SYNC_COUNT,
630 NULL, 0,
631 (char *)&sync_count, &rdata_size);
632
633 if (r)
634 return 0;
635
636 if (sync_count >= lc->region_count)
637 lc->in_sync_hint = lc->region_count;
638
639 return (region_t)sync_count;
640}
641
642/*
643 * userspace_status
644 *
645 * Returns: amount of space consumed
646 */
647static int userspace_status(struct dm_dirty_log *log, status_type_t status_type,
648 char *result, unsigned maxlen)
649{
650 int r = 0;
651 char *table_args;
652 size_t sz = (size_t)maxlen;
653 struct log_c *lc = log->context;
654
655 switch (status_type) {
656 case STATUSTYPE_INFO:
657 r = userspace_do_request(lc, lc->uuid, DM_ULOG_STATUS_INFO,
658 NULL, 0,
659 result, &sz);
660
661 if (r) {
662 sz = 0;
663 DMEMIT("%s 1 COM_FAILURE", log->type->name);
664 }
665 break;
666 case STATUSTYPE_TABLE:
667 sz = 0;
668 table_args = strchr(lc->usr_argv_str, ' ');
669 BUG_ON(!table_args); /* There will always be a ' ' */
670 table_args++;
671
672 DMEMIT("%s %u %s %s ", log->type->name, lc->usr_argc,
673 lc->uuid, table_args);
674 break;
675 }
676 return (r) ? 0 : (int)sz;
677}
678
679/*
680 * userspace_is_remote_recovering
681 *
682 * Returns: 1 if region recovering, 0 otherwise
683 */
684static int userspace_is_remote_recovering(struct dm_dirty_log *log,
685 region_t region)
686{
687 int r;
688 uint64_t region64 = region;
689 struct log_c *lc = log->context;
690 static unsigned long long limit;
691 struct {
692 int64_t is_recovering;
693 uint64_t in_sync_hint;
694 } pkg;
695 size_t rdata_size = sizeof(pkg);
696
697 /*
698 * Once the mirror has been reported to be in-sync,
699 * it will never again ask for recovery work. So,
700 * we can safely say there is not a remote machine
701 * recovering if the device is in-sync. (in_sync_hint
702 * must be reset at resume time.)
703 */
704 if (region < lc->in_sync_hint)
705 return 0;
706 else if (jiffies < limit)
707 return 1;
708
709 limit = jiffies + (HZ / 4);
710 r = userspace_do_request(lc, lc->uuid, DM_ULOG_IS_REMOTE_RECOVERING,
711 (char *)®ion64, sizeof(region64),
712 (char *)&pkg, &rdata_size);
713 if (r)
714 return 1;
715
716 lc->in_sync_hint = pkg.in_sync_hint;
717
718 return (int)pkg.is_recovering;
719}
720
721static struct dm_dirty_log_type _userspace_type = {
722 .name = "userspace",
723 .module = THIS_MODULE,
724 .ctr = userspace_ctr,
725 .dtr = userspace_dtr,
726 .presuspend = userspace_presuspend,
727 .postsuspend = userspace_postsuspend,
728 .resume = userspace_resume,
729 .get_region_size = userspace_get_region_size,
730 .is_clean = userspace_is_clean,
731 .in_sync = userspace_in_sync,
732 .flush = userspace_flush,
733 .mark_region = userspace_mark_region,
734 .clear_region = userspace_clear_region,
735 .get_resync_work = userspace_get_resync_work,
736 .set_region_sync = userspace_set_region_sync,
737 .get_sync_count = userspace_get_sync_count,
738 .status = userspace_status,
739 .is_remote_recovering = userspace_is_remote_recovering,
740};
741
742static int __init userspace_dirty_log_init(void)
743{
744 int r = 0;
745
746 flush_entry_pool = mempool_create(100, flush_entry_alloc,
747 flush_entry_free, NULL);
748
749 if (!flush_entry_pool) {
750 DMWARN("Unable to create flush_entry_pool: No memory.");
751 return -ENOMEM;
752 }
753
754 r = dm_ulog_tfr_init();
755 if (r) {
756 DMWARN("Unable to initialize userspace log communications");
757 mempool_destroy(flush_entry_pool);
758 return r;
759 }
760
761 r = dm_dirty_log_type_register(&_userspace_type);
762 if (r) {
763 DMWARN("Couldn't register userspace dirty log type");
764 dm_ulog_tfr_exit();
765 mempool_destroy(flush_entry_pool);
766 return r;
767 }
768
769 DMINFO("version " DM_LOG_USERSPACE_VSN " loaded");
770 return 0;
771}
772
773static void __exit userspace_dirty_log_exit(void)
774{
775 dm_dirty_log_type_unregister(&_userspace_type);
776 dm_ulog_tfr_exit();
777 mempool_destroy(flush_entry_pool);
778
779 DMINFO("version " DM_LOG_USERSPACE_VSN " unloaded");
780 return;
781}
782
783module_init(userspace_dirty_log_init);
784module_exit(userspace_dirty_log_exit);
785
786MODULE_DESCRIPTION(DM_NAME " userspace dirty log link");
787MODULE_AUTHOR("Jonathan Brassow <dm-devel@redhat.com>");
788MODULE_LICENSE("GPL");
1/*
2 * Copyright (C) 2006-2009 Red Hat, Inc.
3 *
4 * This file is released under the LGPL.
5 */
6
7#include <linux/bio.h>
8#include <linux/slab.h>
9#include <linux/dm-dirty-log.h>
10#include <linux/device-mapper.h>
11#include <linux/dm-log-userspace.h>
12#include <linux/module.h>
13
14#include "dm-log-userspace-transfer.h"
15
16#define DM_LOG_USERSPACE_VSN "1.1.0"
17
18struct flush_entry {
19 int type;
20 region_t region;
21 struct list_head list;
22};
23
24/*
25 * This limit on the number of mark and clear request is, to a degree,
26 * arbitrary. However, there is some basis for the choice in the limits
27 * imposed on the size of data payload by dm-log-userspace-transfer.c:
28 * dm_consult_userspace().
29 */
30#define MAX_FLUSH_GROUP_COUNT 32
31
32struct log_c {
33 struct dm_target *ti;
34 struct dm_dev *log_dev;
35 uint32_t region_size;
36 region_t region_count;
37 uint64_t luid;
38 char uuid[DM_UUID_LEN];
39
40 char *usr_argv_str;
41 uint32_t usr_argc;
42
43 /*
44 * in_sync_hint gets set when doing is_remote_recovering. It
45 * represents the first region that needs recovery. IOW, the
46 * first zero bit of sync_bits. This can be useful for to limit
47 * traffic for calls like is_remote_recovering and get_resync_work,
48 * but be take care in its use for anything else.
49 */
50 uint64_t in_sync_hint;
51
52 /*
53 * Mark and clear requests are held until a flush is issued
54 * so that we can group, and thereby limit, the amount of
55 * network traffic between kernel and userspace. The 'flush_lock'
56 * is used to protect these lists.
57 */
58 spinlock_t flush_lock;
59 struct list_head mark_list;
60 struct list_head clear_list;
61};
62
63static mempool_t *flush_entry_pool;
64
65static void *flush_entry_alloc(gfp_t gfp_mask, void *pool_data)
66{
67 return kmalloc(sizeof(struct flush_entry), gfp_mask);
68}
69
70static void flush_entry_free(void *element, void *pool_data)
71{
72 kfree(element);
73}
74
75static int userspace_do_request(struct log_c *lc, const char *uuid,
76 int request_type, char *data, size_t data_size,
77 char *rdata, size_t *rdata_size)
78{
79 int r;
80
81 /*
82 * If the server isn't there, -ESRCH is returned,
83 * and we must keep trying until the server is
84 * restored.
85 */
86retry:
87 r = dm_consult_userspace(uuid, lc->luid, request_type, data,
88 data_size, rdata, rdata_size);
89
90 if (r != -ESRCH)
91 return r;
92
93 DMERR(" Userspace log server not found.");
94 while (1) {
95 set_current_state(TASK_INTERRUPTIBLE);
96 schedule_timeout(2*HZ);
97 DMWARN("Attempting to contact userspace log server...");
98 r = dm_consult_userspace(uuid, lc->luid, DM_ULOG_CTR,
99 lc->usr_argv_str,
100 strlen(lc->usr_argv_str) + 1,
101 NULL, NULL);
102 if (!r)
103 break;
104 }
105 DMINFO("Reconnected to userspace log server... DM_ULOG_CTR complete");
106 r = dm_consult_userspace(uuid, lc->luid, DM_ULOG_RESUME, NULL,
107 0, NULL, NULL);
108 if (!r)
109 goto retry;
110
111 DMERR("Error trying to resume userspace log: %d", r);
112
113 return -ESRCH;
114}
115
116static int build_constructor_string(struct dm_target *ti,
117 unsigned argc, char **argv,
118 char **ctr_str)
119{
120 int i, str_size;
121 char *str = NULL;
122
123 *ctr_str = NULL;
124
125 for (i = 0, str_size = 0; i < argc; i++)
126 str_size += strlen(argv[i]) + 1; /* +1 for space between args */
127
128 str_size += 20; /* Max number of chars in a printed u64 number */
129
130 str = kzalloc(str_size, GFP_KERNEL);
131 if (!str) {
132 DMWARN("Unable to allocate memory for constructor string");
133 return -ENOMEM;
134 }
135
136 str_size = sprintf(str, "%llu", (unsigned long long)ti->len);
137 for (i = 0; i < argc; i++)
138 str_size += sprintf(str + str_size, " %s", argv[i]);
139
140 *ctr_str = str;
141 return str_size;
142}
143
144/*
145 * userspace_ctr
146 *
147 * argv contains:
148 * <UUID> <other args>
149 * Where 'other args' is the userspace implementation specific log
150 * arguments. An example might be:
151 * <UUID> clustered-disk <arg count> <log dev> <region_size> [[no]sync]
152 *
153 * So, this module will strip off the <UUID> for identification purposes
154 * when communicating with userspace about a log; but will pass on everything
155 * else.
156 */
157static int userspace_ctr(struct dm_dirty_log *log, struct dm_target *ti,
158 unsigned argc, char **argv)
159{
160 int r = 0;
161 int str_size;
162 char *ctr_str = NULL;
163 struct log_c *lc = NULL;
164 uint64_t rdata;
165 size_t rdata_size = sizeof(rdata);
166 char *devices_rdata = NULL;
167 size_t devices_rdata_size = DM_NAME_LEN;
168
169 if (argc < 3) {
170 DMWARN("Too few arguments to userspace dirty log");
171 return -EINVAL;
172 }
173
174 lc = kzalloc(sizeof(*lc), GFP_KERNEL);
175 if (!lc) {
176 DMWARN("Unable to allocate userspace log context.");
177 return -ENOMEM;
178 }
179
180 /* The ptr value is sufficient for local unique id */
181 lc->luid = (unsigned long)lc;
182
183 lc->ti = ti;
184
185 if (strlen(argv[0]) > (DM_UUID_LEN - 1)) {
186 DMWARN("UUID argument too long.");
187 kfree(lc);
188 return -EINVAL;
189 }
190
191 strncpy(lc->uuid, argv[0], DM_UUID_LEN);
192 spin_lock_init(&lc->flush_lock);
193 INIT_LIST_HEAD(&lc->mark_list);
194 INIT_LIST_HEAD(&lc->clear_list);
195
196 str_size = build_constructor_string(ti, argc - 1, argv + 1, &ctr_str);
197 if (str_size < 0) {
198 kfree(lc);
199 return str_size;
200 }
201
202 devices_rdata = kzalloc(devices_rdata_size, GFP_KERNEL);
203 if (!devices_rdata) {
204 DMERR("Failed to allocate memory for device information");
205 r = -ENOMEM;
206 goto out;
207 }
208
209 /*
210 * Send table string and get back any opened device.
211 */
212 r = dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_CTR,
213 ctr_str, str_size,
214 devices_rdata, &devices_rdata_size);
215
216 if (r < 0) {
217 if (r == -ESRCH)
218 DMERR("Userspace log server not found");
219 else
220 DMERR("Userspace log server failed to create log");
221 goto out;
222 }
223
224 /* Since the region size does not change, get it now */
225 rdata_size = sizeof(rdata);
226 r = dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_GET_REGION_SIZE,
227 NULL, 0, (char *)&rdata, &rdata_size);
228
229 if (r) {
230 DMERR("Failed to get region size of dirty log");
231 goto out;
232 }
233
234 lc->region_size = (uint32_t)rdata;
235 lc->region_count = dm_sector_div_up(ti->len, lc->region_size);
236
237 if (devices_rdata_size) {
238 if (devices_rdata[devices_rdata_size - 1] != '\0') {
239 DMERR("DM_ULOG_CTR device return string not properly terminated");
240 r = -EINVAL;
241 goto out;
242 }
243 r = dm_get_device(ti, devices_rdata,
244 dm_table_get_mode(ti->table), &lc->log_dev);
245 if (r)
246 DMERR("Failed to register %s with device-mapper",
247 devices_rdata);
248 }
249out:
250 kfree(devices_rdata);
251 if (r) {
252 kfree(lc);
253 kfree(ctr_str);
254 } else {
255 lc->usr_argv_str = ctr_str;
256 lc->usr_argc = argc;
257 log->context = lc;
258 }
259
260 return r;
261}
262
263static void userspace_dtr(struct dm_dirty_log *log)
264{
265 struct log_c *lc = log->context;
266
267 (void) dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_DTR,
268 NULL, 0,
269 NULL, NULL);
270
271 if (lc->log_dev)
272 dm_put_device(lc->ti, lc->log_dev);
273
274 kfree(lc->usr_argv_str);
275 kfree(lc);
276
277 return;
278}
279
280static int userspace_presuspend(struct dm_dirty_log *log)
281{
282 int r;
283 struct log_c *lc = log->context;
284
285 r = dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_PRESUSPEND,
286 NULL, 0,
287 NULL, NULL);
288
289 return r;
290}
291
292static int userspace_postsuspend(struct dm_dirty_log *log)
293{
294 int r;
295 struct log_c *lc = log->context;
296
297 r = dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_POSTSUSPEND,
298 NULL, 0,
299 NULL, NULL);
300
301 return r;
302}
303
304static int userspace_resume(struct dm_dirty_log *log)
305{
306 int r;
307 struct log_c *lc = log->context;
308
309 lc->in_sync_hint = 0;
310 r = dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_RESUME,
311 NULL, 0,
312 NULL, NULL);
313
314 return r;
315}
316
317static uint32_t userspace_get_region_size(struct dm_dirty_log *log)
318{
319 struct log_c *lc = log->context;
320
321 return lc->region_size;
322}
323
324/*
325 * userspace_is_clean
326 *
327 * Check whether a region is clean. If there is any sort of
328 * failure when consulting the server, we return not clean.
329 *
330 * Returns: 1 if clean, 0 otherwise
331 */
332static int userspace_is_clean(struct dm_dirty_log *log, region_t region)
333{
334 int r;
335 uint64_t region64 = (uint64_t)region;
336 int64_t is_clean;
337 size_t rdata_size;
338 struct log_c *lc = log->context;
339
340 rdata_size = sizeof(is_clean);
341 r = userspace_do_request(lc, lc->uuid, DM_ULOG_IS_CLEAN,
342 (char *)®ion64, sizeof(region64),
343 (char *)&is_clean, &rdata_size);
344
345 return (r) ? 0 : (int)is_clean;
346}
347
348/*
349 * userspace_in_sync
350 *
351 * Check if the region is in-sync. If there is any sort
352 * of failure when consulting the server, we assume that
353 * the region is not in sync.
354 *
355 * If 'can_block' is set, return immediately
356 *
357 * Returns: 1 if in-sync, 0 if not-in-sync, -EWOULDBLOCK
358 */
359static int userspace_in_sync(struct dm_dirty_log *log, region_t region,
360 int can_block)
361{
362 int r;
363 uint64_t region64 = region;
364 int64_t in_sync;
365 size_t rdata_size;
366 struct log_c *lc = log->context;
367
368 /*
369 * We can never respond directly - even if in_sync_hint is
370 * set. This is because another machine could see a device
371 * failure and mark the region out-of-sync. If we don't go
372 * to userspace to ask, we might think the region is in-sync
373 * and allow a read to pick up data that is stale. (This is
374 * very unlikely if a device actually fails; but it is very
375 * likely if a connection to one device from one machine fails.)
376 *
377 * There still might be a problem if the mirror caches the region
378 * state as in-sync... but then this call would not be made. So,
379 * that is a mirror problem.
380 */
381 if (!can_block)
382 return -EWOULDBLOCK;
383
384 rdata_size = sizeof(in_sync);
385 r = userspace_do_request(lc, lc->uuid, DM_ULOG_IN_SYNC,
386 (char *)®ion64, sizeof(region64),
387 (char *)&in_sync, &rdata_size);
388 return (r) ? 0 : (int)in_sync;
389}
390
391static int flush_one_by_one(struct log_c *lc, struct list_head *flush_list)
392{
393 int r = 0;
394 struct flush_entry *fe;
395
396 list_for_each_entry(fe, flush_list, list) {
397 r = userspace_do_request(lc, lc->uuid, fe->type,
398 (char *)&fe->region,
399 sizeof(fe->region),
400 NULL, NULL);
401 if (r)
402 break;
403 }
404
405 return r;
406}
407
408static int flush_by_group(struct log_c *lc, struct list_head *flush_list)
409{
410 int r = 0;
411 int count;
412 uint32_t type = 0;
413 struct flush_entry *fe, *tmp_fe;
414 LIST_HEAD(tmp_list);
415 uint64_t group[MAX_FLUSH_GROUP_COUNT];
416
417 /*
418 * Group process the requests
419 */
420 while (!list_empty(flush_list)) {
421 count = 0;
422
423 list_for_each_entry_safe(fe, tmp_fe, flush_list, list) {
424 group[count] = fe->region;
425 count++;
426
427 list_move(&fe->list, &tmp_list);
428
429 type = fe->type;
430 if (count >= MAX_FLUSH_GROUP_COUNT)
431 break;
432 }
433
434 r = userspace_do_request(lc, lc->uuid, type,
435 (char *)(group),
436 count * sizeof(uint64_t),
437 NULL, NULL);
438 if (r) {
439 /* Group send failed. Attempt one-by-one. */
440 list_splice_init(&tmp_list, flush_list);
441 r = flush_one_by_one(lc, flush_list);
442 break;
443 }
444 }
445
446 /*
447 * Must collect flush_entrys that were successfully processed
448 * as a group so that they will be free'd by the caller.
449 */
450 list_splice_init(&tmp_list, flush_list);
451
452 return r;
453}
454
455/*
456 * userspace_flush
457 *
458 * This function is ok to block.
459 * The flush happens in two stages. First, it sends all
460 * clear/mark requests that are on the list. Then it
461 * tells the server to commit them. This gives the
462 * server a chance to optimise the commit, instead of
463 * doing it for every request.
464 *
465 * Additionally, we could implement another thread that
466 * sends the requests up to the server - reducing the
467 * load on flush. Then the flush would have less in
468 * the list and be responsible for the finishing commit.
469 *
470 * Returns: 0 on success, < 0 on failure
471 */
472static int userspace_flush(struct dm_dirty_log *log)
473{
474 int r = 0;
475 unsigned long flags;
476 struct log_c *lc = log->context;
477 LIST_HEAD(mark_list);
478 LIST_HEAD(clear_list);
479 struct flush_entry *fe, *tmp_fe;
480
481 spin_lock_irqsave(&lc->flush_lock, flags);
482 list_splice_init(&lc->mark_list, &mark_list);
483 list_splice_init(&lc->clear_list, &clear_list);
484 spin_unlock_irqrestore(&lc->flush_lock, flags);
485
486 if (list_empty(&mark_list) && list_empty(&clear_list))
487 return 0;
488
489 r = flush_by_group(lc, &mark_list);
490 if (r)
491 goto fail;
492
493 r = flush_by_group(lc, &clear_list);
494 if (r)
495 goto fail;
496
497 r = userspace_do_request(lc, lc->uuid, DM_ULOG_FLUSH,
498 NULL, 0, NULL, NULL);
499
500fail:
501 /*
502 * We can safely remove these entries, even if failure.
503 * Calling code will receive an error and will know that
504 * the log facility has failed.
505 */
506 list_for_each_entry_safe(fe, tmp_fe, &mark_list, list) {
507 list_del(&fe->list);
508 mempool_free(fe, flush_entry_pool);
509 }
510 list_for_each_entry_safe(fe, tmp_fe, &clear_list, list) {
511 list_del(&fe->list);
512 mempool_free(fe, flush_entry_pool);
513 }
514
515 if (r)
516 dm_table_event(lc->ti->table);
517
518 return r;
519}
520
521/*
522 * userspace_mark_region
523 *
524 * This function should avoid blocking unless absolutely required.
525 * (Memory allocation is valid for blocking.)
526 */
527static void userspace_mark_region(struct dm_dirty_log *log, region_t region)
528{
529 unsigned long flags;
530 struct log_c *lc = log->context;
531 struct flush_entry *fe;
532
533 /* Wait for an allocation, but _never_ fail */
534 fe = mempool_alloc(flush_entry_pool, GFP_NOIO);
535 BUG_ON(!fe);
536
537 spin_lock_irqsave(&lc->flush_lock, flags);
538 fe->type = DM_ULOG_MARK_REGION;
539 fe->region = region;
540 list_add(&fe->list, &lc->mark_list);
541 spin_unlock_irqrestore(&lc->flush_lock, flags);
542
543 return;
544}
545
546/*
547 * userspace_clear_region
548 *
549 * This function must not block.
550 * So, the alloc can't block. In the worst case, it is ok to
551 * fail. It would simply mean we can't clear the region.
552 * Does nothing to current sync context, but does mean
553 * the region will be re-sync'ed on a reload of the mirror
554 * even though it is in-sync.
555 */
556static void userspace_clear_region(struct dm_dirty_log *log, region_t region)
557{
558 unsigned long flags;
559 struct log_c *lc = log->context;
560 struct flush_entry *fe;
561
562 /*
563 * If we fail to allocate, we skip the clearing of
564 * the region. This doesn't hurt us in any way, except
565 * to cause the region to be resync'ed when the
566 * device is activated next time.
567 */
568 fe = mempool_alloc(flush_entry_pool, GFP_ATOMIC);
569 if (!fe) {
570 DMERR("Failed to allocate memory to clear region.");
571 return;
572 }
573
574 spin_lock_irqsave(&lc->flush_lock, flags);
575 fe->type = DM_ULOG_CLEAR_REGION;
576 fe->region = region;
577 list_add(&fe->list, &lc->clear_list);
578 spin_unlock_irqrestore(&lc->flush_lock, flags);
579
580 return;
581}
582
583/*
584 * userspace_get_resync_work
585 *
586 * Get a region that needs recovery. It is valid to return
587 * an error for this function.
588 *
589 * Returns: 1 if region filled, 0 if no work, <0 on error
590 */
591static int userspace_get_resync_work(struct dm_dirty_log *log, region_t *region)
592{
593 int r;
594 size_t rdata_size;
595 struct log_c *lc = log->context;
596 struct {
597 int64_t i; /* 64-bit for mix arch compatibility */
598 region_t r;
599 } pkg;
600
601 if (lc->in_sync_hint >= lc->region_count)
602 return 0;
603
604 rdata_size = sizeof(pkg);
605 r = userspace_do_request(lc, lc->uuid, DM_ULOG_GET_RESYNC_WORK,
606 NULL, 0,
607 (char *)&pkg, &rdata_size);
608
609 *region = pkg.r;
610 return (r) ? r : (int)pkg.i;
611}
612
613/*
614 * userspace_set_region_sync
615 *
616 * Set the sync status of a given region. This function
617 * must not fail.
618 */
619static void userspace_set_region_sync(struct dm_dirty_log *log,
620 region_t region, int in_sync)
621{
622 int r;
623 struct log_c *lc = log->context;
624 struct {
625 region_t r;
626 int64_t i;
627 } pkg;
628
629 pkg.r = region;
630 pkg.i = (int64_t)in_sync;
631
632 r = userspace_do_request(lc, lc->uuid, DM_ULOG_SET_REGION_SYNC,
633 (char *)&pkg, sizeof(pkg),
634 NULL, NULL);
635
636 /*
637 * It would be nice to be able to report failures.
638 * However, it is easy emough to detect and resolve.
639 */
640 return;
641}
642
643/*
644 * userspace_get_sync_count
645 *
646 * If there is any sort of failure when consulting the server,
647 * we assume that the sync count is zero.
648 *
649 * Returns: sync count on success, 0 on failure
650 */
651static region_t userspace_get_sync_count(struct dm_dirty_log *log)
652{
653 int r;
654 size_t rdata_size;
655 uint64_t sync_count;
656 struct log_c *lc = log->context;
657
658 rdata_size = sizeof(sync_count);
659 r = userspace_do_request(lc, lc->uuid, DM_ULOG_GET_SYNC_COUNT,
660 NULL, 0,
661 (char *)&sync_count, &rdata_size);
662
663 if (r)
664 return 0;
665
666 if (sync_count >= lc->region_count)
667 lc->in_sync_hint = lc->region_count;
668
669 return (region_t)sync_count;
670}
671
672/*
673 * userspace_status
674 *
675 * Returns: amount of space consumed
676 */
677static int userspace_status(struct dm_dirty_log *log, status_type_t status_type,
678 char *result, unsigned maxlen)
679{
680 int r = 0;
681 char *table_args;
682 size_t sz = (size_t)maxlen;
683 struct log_c *lc = log->context;
684
685 switch (status_type) {
686 case STATUSTYPE_INFO:
687 r = userspace_do_request(lc, lc->uuid, DM_ULOG_STATUS_INFO,
688 NULL, 0,
689 result, &sz);
690
691 if (r) {
692 sz = 0;
693 DMEMIT("%s 1 COM_FAILURE", log->type->name);
694 }
695 break;
696 case STATUSTYPE_TABLE:
697 sz = 0;
698 table_args = strchr(lc->usr_argv_str, ' ');
699 BUG_ON(!table_args); /* There will always be a ' ' */
700 table_args++;
701
702 DMEMIT("%s %u %s %s ", log->type->name, lc->usr_argc,
703 lc->uuid, table_args);
704 break;
705 }
706 return (r) ? 0 : (int)sz;
707}
708
709/*
710 * userspace_is_remote_recovering
711 *
712 * Returns: 1 if region recovering, 0 otherwise
713 */
714static int userspace_is_remote_recovering(struct dm_dirty_log *log,
715 region_t region)
716{
717 int r;
718 uint64_t region64 = region;
719 struct log_c *lc = log->context;
720 static unsigned long long limit;
721 struct {
722 int64_t is_recovering;
723 uint64_t in_sync_hint;
724 } pkg;
725 size_t rdata_size = sizeof(pkg);
726
727 /*
728 * Once the mirror has been reported to be in-sync,
729 * it will never again ask for recovery work. So,
730 * we can safely say there is not a remote machine
731 * recovering if the device is in-sync. (in_sync_hint
732 * must be reset at resume time.)
733 */
734 if (region < lc->in_sync_hint)
735 return 0;
736 else if (jiffies < limit)
737 return 1;
738
739 limit = jiffies + (HZ / 4);
740 r = userspace_do_request(lc, lc->uuid, DM_ULOG_IS_REMOTE_RECOVERING,
741 (char *)®ion64, sizeof(region64),
742 (char *)&pkg, &rdata_size);
743 if (r)
744 return 1;
745
746 lc->in_sync_hint = pkg.in_sync_hint;
747
748 return (int)pkg.is_recovering;
749}
750
751static struct dm_dirty_log_type _userspace_type = {
752 .name = "userspace",
753 .module = THIS_MODULE,
754 .ctr = userspace_ctr,
755 .dtr = userspace_dtr,
756 .presuspend = userspace_presuspend,
757 .postsuspend = userspace_postsuspend,
758 .resume = userspace_resume,
759 .get_region_size = userspace_get_region_size,
760 .is_clean = userspace_is_clean,
761 .in_sync = userspace_in_sync,
762 .flush = userspace_flush,
763 .mark_region = userspace_mark_region,
764 .clear_region = userspace_clear_region,
765 .get_resync_work = userspace_get_resync_work,
766 .set_region_sync = userspace_set_region_sync,
767 .get_sync_count = userspace_get_sync_count,
768 .status = userspace_status,
769 .is_remote_recovering = userspace_is_remote_recovering,
770};
771
772static int __init userspace_dirty_log_init(void)
773{
774 int r = 0;
775
776 flush_entry_pool = mempool_create(100, flush_entry_alloc,
777 flush_entry_free, NULL);
778
779 if (!flush_entry_pool) {
780 DMWARN("Unable to create flush_entry_pool: No memory.");
781 return -ENOMEM;
782 }
783
784 r = dm_ulog_tfr_init();
785 if (r) {
786 DMWARN("Unable to initialize userspace log communications");
787 mempool_destroy(flush_entry_pool);
788 return r;
789 }
790
791 r = dm_dirty_log_type_register(&_userspace_type);
792 if (r) {
793 DMWARN("Couldn't register userspace dirty log type");
794 dm_ulog_tfr_exit();
795 mempool_destroy(flush_entry_pool);
796 return r;
797 }
798
799 DMINFO("version " DM_LOG_USERSPACE_VSN " loaded");
800 return 0;
801}
802
803static void __exit userspace_dirty_log_exit(void)
804{
805 dm_dirty_log_type_unregister(&_userspace_type);
806 dm_ulog_tfr_exit();
807 mempool_destroy(flush_entry_pool);
808
809 DMINFO("version " DM_LOG_USERSPACE_VSN " unloaded");
810 return;
811}
812
813module_init(userspace_dirty_log_init);
814module_exit(userspace_dirty_log_exit);
815
816MODULE_DESCRIPTION(DM_NAME " userspace dirty log link");
817MODULE_AUTHOR("Jonathan Brassow <dm-devel@redhat.com>");
818MODULE_LICENSE("GPL");