root/drivers/md/dm-log-userspace-base.c

DEFINITIONS

1. userspace_do_request
2. build_constructor_string
3. do_flush
4. userspace_ctr
5. userspace_dtr
6. userspace_presuspend
7. userspace_postsuspend
8. userspace_resume
9. userspace_get_region_size
10. userspace_is_clean
11. userspace_in_sync
12. flush_one_by_one
13. flush_by_group
14. userspace_flush
15. userspace_mark_region
16. userspace_clear_region
17. userspace_get_resync_work
18. userspace_set_region_sync
19. userspace_get_sync_count
20. userspace_status
21. userspace_is_remote_recovering
22. userspace_dirty_log_init
23. userspace_dirty_log_exit

   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/jiffies.h>
  10 #include <linux/dm-dirty-log.h>
  11 #include <linux/device-mapper.h>
  12 #include <linux/dm-log-userspace.h>
  13 #include <linux/module.h>
  14 #include <linux/workqueue.h>
  15 
  16 #include "dm-log-userspace-transfer.h"
  17 
  18 #define DM_LOG_USERSPACE_VSN "1.3.0"
  19 
  20 #define FLUSH_ENTRY_POOL_SIZE 16
  21 
  22 struct dm_dirty_log_flush_entry {
  23         int type;
  24         region_t region;
  25         struct list_head list;
  26 };
  27 
  28 /*
  29  * This limit on the number of mark and clear request is, to a degree,
  30  * arbitrary.  However, there is some basis for the choice in the limits
  31  * imposed on the size of data payload by dm-log-userspace-transfer.c:
  32  * dm_consult_userspace().
  33  */
  34 #define MAX_FLUSH_GROUP_COUNT 32
  35 
  36 struct log_c {
  37         struct dm_target *ti;
  38         struct dm_dev *log_dev;
  39 
  40         char *usr_argv_str;
  41         uint32_t usr_argc;
  42 
  43         uint32_t region_size;
  44         region_t region_count;
  45         uint64_t luid;
  46         char uuid[DM_UUID_LEN];
  47 
  48         /*
  49          * Mark and clear requests are held until a flush is issued
  50          * so that we can group, and thereby limit, the amount of
  51          * network traffic between kernel and userspace.  The 'flush_lock'
  52          * is used to protect these lists.
  53          */
  54         spinlock_t flush_lock;
  55         struct list_head mark_list;
  56         struct list_head clear_list;
  57 
  58         /*
  59          * in_sync_hint gets set when doing is_remote_recovering.  It
  60          * represents the first region that needs recovery.  IOW, the
  61          * first zero bit of sync_bits.  This can be useful for to limit
  62          * traffic for calls like is_remote_recovering and get_resync_work,
  63          * but be take care in its use for anything else.
  64          */
  65         uint64_t in_sync_hint;
  66 
  67         /*
  68          * Workqueue for flush of clear region requests.
  69          */
  70         struct workqueue_struct *dmlog_wq;
  71         struct delayed_work flush_log_work;
  72         atomic_t sched_flush;
  73 
  74         /*
  75          * Combine userspace flush and mark requests for efficiency.
  76          */
  77         uint32_t integrated_flush;
  78 
  79         mempool_t flush_entry_pool;
  80 };
  81 
  82 static struct kmem_cache *_flush_entry_cache;
  83 
  84 static int userspace_do_request(struct log_c *lc, const char *uuid,
  85                                 int request_type, char *data, size_t data_size,
  86                                 char *rdata, size_t *rdata_size)
  87 {
  88         int r;
  89 
  90         /*
  91          * If the server isn't there, -ESRCH is returned,
  92          * and we must keep trying until the server is
  93          * restored.
  94          */
  95 retry:
  96         r = dm_consult_userspace(uuid, lc->luid, request_type, data,
  97                                  data_size, rdata, rdata_size);
  98 
  99         if (r != -ESRCH)
 100                 return r;
 101 
 102         DMERR(" Userspace log server not found.");
 103         while (1) {
 104                 set_current_state(TASK_INTERRUPTIBLE);
 105                 schedule_timeout(2*HZ);
 106                 DMWARN("Attempting to contact userspace log server...");
 107                 r = dm_consult_userspace(uuid, lc->luid, DM_ULOG_CTR,
 108                                          lc->usr_argv_str,
 109                                          strlen(lc->usr_argv_str) + 1,
 110                                          NULL, NULL);
 111                 if (!r)
 112                         break;
 113         }
 114         DMINFO("Reconnected to userspace log server... DM_ULOG_CTR complete");
 115         r = dm_consult_userspace(uuid, lc->luid, DM_ULOG_RESUME, NULL,
 116                                  0, NULL, NULL);
 117         if (!r)
 118                 goto retry;
 119 
 120         DMERR("Error trying to resume userspace log: %d", r);
 121 
 122         return -ESRCH;
 123 }
 124 
 125 static int build_constructor_string(struct dm_target *ti,
 126                                     unsigned argc, char **argv,
 127                                     char **ctr_str)
 128 {
 129         int i, str_size;
 130         char *str = NULL;
 131 
 132         *ctr_str = NULL;
 133 
 134         /*
 135          * Determine overall size of the string.
 136          */
 137         for (i = 0, str_size = 0; i < argc; i++)
 138                 str_size += strlen(argv[i]) + 1; /* +1 for space between args */
 139 
 140         str_size += 20; /* Max number of chars in a printed u64 number */
 141 
 142         str = kzalloc(str_size, GFP_KERNEL);
 143         if (!str) {
 144                 DMWARN("Unable to allocate memory for constructor string");
 145                 return -ENOMEM;
 146         }
 147 
 148         str_size = sprintf(str, "%llu", (unsigned long long)ti->len);
 149         for (i = 0; i < argc; i++)
 150                 str_size += sprintf(str + str_size, " %s", argv[i]);
 151 
 152         *ctr_str = str;
 153         return str_size;
 154 }
 155 
 156 static void do_flush(struct work_struct *work)
 157 {
 158         int r;
 159         struct log_c *lc = container_of(work, struct log_c, flush_log_work.work);
 160 
 161         atomic_set(&lc->sched_flush, 0);
 162 
 163         r = userspace_do_request(lc, lc->uuid, DM_ULOG_FLUSH, NULL, 0, NULL, NULL);
 164 
 165         if (r)
 166                 dm_table_event(lc->ti->table);
 167 }
 168 
 169 /*
 170  * userspace_ctr
 171  *
 172  * argv contains:
 173  *      <UUID> [integrated_flush] <other args>
 174  * Where 'other args' are the userspace implementation-specific log
 175  * arguments.
 176  *
 177  * Example:
 178  *      <UUID> [integrated_flush] clustered-disk <arg count> <log dev>
 179  *      <region_size> [[no]sync]
 180  *
 181  * This module strips off the <UUID> and uses it for identification
 182  * purposes when communicating with userspace about a log.
 183  *
 184  * If integrated_flush is defined, the kernel combines flush
 185  * and mark requests.
 186  *
 187  * The rest of the line, beginning with 'clustered-disk', is passed
 188  * to the userspace ctr function.
 189  */
 190 static int userspace_ctr(struct dm_dirty_log *log, struct dm_target *ti,
 191                          unsigned argc, char **argv)
 192 {
 193         int r = 0;
 194         int str_size;
 195         char *ctr_str = NULL;
 196         struct log_c *lc = NULL;
 197         uint64_t rdata;
 198         size_t rdata_size = sizeof(rdata);
 199         char *devices_rdata = NULL;
 200         size_t devices_rdata_size = DM_NAME_LEN;
 201 
 202         if (argc < 3) {
 203                 DMWARN("Too few arguments to userspace dirty log");
 204                 return -EINVAL;
 205         }
 206 
 207         lc = kzalloc(sizeof(*lc), GFP_KERNEL);
 208         if (!lc) {
 209                 DMWARN("Unable to allocate userspace log context.");
 210                 return -ENOMEM;
 211         }
 212 
 213         /* The ptr value is sufficient for local unique id */
 214         lc->luid = (unsigned long)lc;
 215 
 216         lc->ti = ti;
 217 
 218         if (strlen(argv[0]) > (DM_UUID_LEN - 1)) {
 219                 DMWARN("UUID argument too long.");
 220                 kfree(lc);
 221                 return -EINVAL;
 222         }
 223 
 224         lc->usr_argc = argc;
 225 
 226         strncpy(lc->uuid, argv[0], DM_UUID_LEN);
 227         argc--;
 228         argv++;
 229         spin_lock_init(&lc->flush_lock);
 230         INIT_LIST_HEAD(&lc->mark_list);
 231         INIT_LIST_HEAD(&lc->clear_list);
 232 
 233         if (!strcasecmp(argv[0], "integrated_flush")) {
 234                 lc->integrated_flush = 1;
 235                 argc--;
 236                 argv++;
 237         }
 238 
 239         str_size = build_constructor_string(ti, argc, argv, &ctr_str);
 240         if (str_size < 0) {
 241                 kfree(lc);
 242                 return str_size;
 243         }
 244 
 245         devices_rdata = kzalloc(devices_rdata_size, GFP_KERNEL);
 246         if (!devices_rdata) {
 247                 DMERR("Failed to allocate memory for device information");
 248                 r = -ENOMEM;
 249                 goto out;
 250         }
 251 
 252         r = mempool_init_slab_pool(&lc->flush_entry_pool, FLUSH_ENTRY_POOL_SIZE,
 253                                    _flush_entry_cache);
 254         if (r) {
 255                 DMERR("Failed to create flush_entry_pool");
 256                 goto out;
 257         }
 258 
 259         /*
 260          * Send table string and get back any opened device.
 261          */
 262         r = dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_CTR,
 263                                  ctr_str, str_size,
 264                                  devices_rdata, &devices_rdata_size);
 265 
 266         if (r < 0) {
 267                 if (r == -ESRCH)
 268                         DMERR("Userspace log server not found");
 269                 else
 270                         DMERR("Userspace log server failed to create log");
 271                 goto out;
 272         }
 273 
 274         /* Since the region size does not change, get it now */
 275         rdata_size = sizeof(rdata);
 276         r = dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_GET_REGION_SIZE,
 277                                  NULL, 0, (char *)&rdata, &rdata_size);
 278 
 279         if (r) {
 280                 DMERR("Failed to get region size of dirty log");
 281                 goto out;
 282         }
 283 
 284         lc->region_size = (uint32_t)rdata;
 285         lc->region_count = dm_sector_div_up(ti->len, lc->region_size);
 286 
 287         if (devices_rdata_size) {
 288                 if (devices_rdata[devices_rdata_size - 1] != '\0') {
 289                         DMERR("DM_ULOG_CTR device return string not properly terminated");
 290                         r = -EINVAL;
 291                         goto out;
 292                 }
 293                 r = dm_get_device(ti, devices_rdata,
 294                                   dm_table_get_mode(ti->table), &lc->log_dev);
 295                 if (r)
 296                         DMERR("Failed to register %s with device-mapper",
 297                               devices_rdata);
 298         }
 299 
 300         if (lc->integrated_flush) {
 301                 lc->dmlog_wq = alloc_workqueue("dmlogd", WQ_MEM_RECLAIM, 0);
 302                 if (!lc->dmlog_wq) {
 303                         DMERR("couldn't start dmlogd");
 304                         r = -ENOMEM;
 305                         goto out;
 306                 }
 307 
 308                 INIT_DELAYED_WORK(&lc->flush_log_work, do_flush);
 309                 atomic_set(&lc->sched_flush, 0);
 310         }
 311 
 312 out:
 313         kfree(devices_rdata);
 314         if (r) {
 315                 mempool_exit(&lc->flush_entry_pool);
 316                 kfree(lc);
 317                 kfree(ctr_str);
 318         } else {
 319                 lc->usr_argv_str = ctr_str;
 320                 log->context = lc;
 321         }
 322 
 323         return r;
 324 }
 325 
 326 static void userspace_dtr(struct dm_dirty_log *log)
 327 {
 328         struct log_c *lc = log->context;
 329 
 330         if (lc->integrated_flush) {
 331                 /* flush workqueue */
 332                 if (atomic_read(&lc->sched_flush))
 333                         flush_delayed_work(&lc->flush_log_work);
 334 
 335                 destroy_workqueue(lc->dmlog_wq);
 336         }
 337 
 338         (void) dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_DTR,
 339                                     NULL, 0, NULL, NULL);
 340 
 341         if (lc->log_dev)
 342                 dm_put_device(lc->ti, lc->log_dev);
 343 
 344         mempool_exit(&lc->flush_entry_pool);
 345 
 346         kfree(lc->usr_argv_str);
 347         kfree(lc);
 348 
 349         return;
 350 }
 351 
 352 static int userspace_presuspend(struct dm_dirty_log *log)
 353 {
 354         int r;
 355         struct log_c *lc = log->context;
 356 
 357         r = dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_PRESUSPEND,
 358                                  NULL, 0, NULL, NULL);
 359 
 360         return r;
 361 }
 362 
 363 static int userspace_postsuspend(struct dm_dirty_log *log)
 364 {
 365         int r;
 366         struct log_c *lc = log->context;
 367 
 368         /*
 369          * Run planned flush earlier.
 370          */
 371         if (lc->integrated_flush && atomic_read(&lc->sched_flush))
 372                 flush_delayed_work(&lc->flush_log_work);
 373 
 374         r = dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_POSTSUSPEND,
 375                                  NULL, 0, NULL, NULL);
 376 
 377         return r;
 378 }
 379 
 380 static int userspace_resume(struct dm_dirty_log *log)
 381 {
 382         int r;
 383         struct log_c *lc = log->context;
 384 
 385         lc->in_sync_hint = 0;
 386         r = dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_RESUME,
 387                                  NULL, 0, NULL, NULL);
 388 
 389         return r;
 390 }
 391 
 392 static uint32_t userspace_get_region_size(struct dm_dirty_log *log)
 393 {
 394         struct log_c *lc = log->context;
 395 
 396         return lc->region_size;
 397 }
 398 
 399 /*
 400  * userspace_is_clean
 401  *
 402  * Check whether a region is clean.  If there is any sort of
 403  * failure when consulting the server, we return not clean.
 404  *
 405  * Returns: 1 if clean, 0 otherwise
 406  */
 407 static int userspace_is_clean(struct dm_dirty_log *log, region_t region)
 408 {
 409         int r;
 410         uint64_t region64 = (uint64_t)region;
 411         int64_t is_clean;
 412         size_t rdata_size;
 413         struct log_c *lc = log->context;
 414 
 415         rdata_size = sizeof(is_clean);
 416         r = userspace_do_request(lc, lc->uuid, DM_ULOG_IS_CLEAN,
 417                                  (char *)&region64, sizeof(region64),
 418                                  (char *)&is_clean, &rdata_size);
 419 
 420         return (r) ? 0 : (int)is_clean;
 421 }
 422 
 423 /*
 424  * userspace_in_sync
 425  *
 426  * Check if the region is in-sync.  If there is any sort
 427  * of failure when consulting the server, we assume that
 428  * the region is not in sync.
 429  *
 430  * If 'can_block' is set, return immediately
 431  *
 432  * Returns: 1 if in-sync, 0 if not-in-sync, -EWOULDBLOCK
 433  */
 434 static int userspace_in_sync(struct dm_dirty_log *log, region_t region,
 435                              int can_block)
 436 {
 437         int r;
 438         uint64_t region64 = region;
 439         int64_t in_sync;
 440         size_t rdata_size;
 441         struct log_c *lc = log->context;
 442 
 443         /*
 444          * We can never respond directly - even if in_sync_hint is
 445          * set.  This is because another machine could see a device
 446          * failure and mark the region out-of-sync.  If we don't go
 447          * to userspace to ask, we might think the region is in-sync
 448          * and allow a read to pick up data that is stale.  (This is
 449          * very unlikely if a device actually fails; but it is very
 450          * likely if a connection to one device from one machine fails.)
 451          *
 452          * There still might be a problem if the mirror caches the region
 453          * state as in-sync... but then this call would not be made.  So,
 454          * that is a mirror problem.
 455          */
 456         if (!can_block)
 457                 return -EWOULDBLOCK;
 458 
 459         rdata_size = sizeof(in_sync);
 460         r = userspace_do_request(lc, lc->uuid, DM_ULOG_IN_SYNC,
 461                                  (char *)&region64, sizeof(region64),
 462                                  (char *)&in_sync, &rdata_size);
 463         return (r) ? 0 : (int)in_sync;
 464 }
 465 
 466 static int flush_one_by_one(struct log_c *lc, struct list_head *flush_list)
 467 {
 468         int r = 0;
 469         struct dm_dirty_log_flush_entry *fe;
 470 
 471         list_for_each_entry(fe, flush_list, list) {
 472                 r = userspace_do_request(lc, lc->uuid, fe->type,
 473                                          (char *)&fe->region,
 474                                          sizeof(fe->region),
 475                                          NULL, NULL);
 476                 if (r)
 477                         break;
 478         }
 479 
 480         return r;
 481 }
 482 
 483 static int flush_by_group(struct log_c *lc, struct list_head *flush_list,
 484                           int flush_with_payload)
 485 {
 486         int r = 0;
 487         int count;
 488         uint32_t type = 0;
 489         struct dm_dirty_log_flush_entry *fe, *tmp_fe;
 490         LIST_HEAD(tmp_list);
 491         uint64_t group[MAX_FLUSH_GROUP_COUNT];
 492 
 493         /*
 494          * Group process the requests
 495          */
 496         while (!list_empty(flush_list)) {
 497                 count = 0;
 498 
 499                 list_for_each_entry_safe(fe, tmp_fe, flush_list, list) {
 500                         group[count] = fe->region;
 501                         count++;
 502 
 503                         list_move(&fe->list, &tmp_list);
 504 
 505                         type = fe->type;
 506                         if (count >= MAX_FLUSH_GROUP_COUNT)
 507                                 break;
 508                 }
 509 
 510                 if (flush_with_payload) {
 511                         r = userspace_do_request(lc, lc->uuid, DM_ULOG_FLUSH,
 512                                                  (char *)(group),
 513                                                  count * sizeof(uint64_t),
 514                                                  NULL, NULL);
 515                         /*
 516                          * Integrated flush failed.
 517                          */
 518                         if (r)
 519                                 break;
 520                 } else {
 521                         r = userspace_do_request(lc, lc->uuid, type,
 522                                                  (char *)(group),
 523                                                  count * sizeof(uint64_t),
 524                                                  NULL, NULL);
 525                         if (r) {
 526                                 /*
 527                                  * Group send failed.  Attempt one-by-one.
 528                                  */
 529                                 list_splice_init(&tmp_list, flush_list);
 530                                 r = flush_one_by_one(lc, flush_list);
 531                                 break;
 532                         }
 533                 }
 534         }
 535 
 536         /*
 537          * Must collect flush_entrys that were successfully processed
 538          * as a group so that they will be free'd by the caller.
 539          */
 540         list_splice_init(&tmp_list, flush_list);
 541 
 542         return r;
 543 }
 544 
 545 /*
 546  * userspace_flush
 547  *
 548  * This function is ok to block.
 549  * The flush happens in two stages.  First, it sends all
 550  * clear/mark requests that are on the list.  Then it
 551  * tells the server to commit them.  This gives the
 552  * server a chance to optimise the commit, instead of
 553  * doing it for every request.
 554  *
 555  * Additionally, we could implement another thread that
 556  * sends the requests up to the server - reducing the
 557  * load on flush.  Then the flush would have less in
 558  * the list and be responsible for the finishing commit.
 559  *
 560  * Returns: 0 on success, < 0 on failure
 561  */
 562 static int userspace_flush(struct dm_dirty_log *log)
 563 {
 564         int r = 0;
 565         unsigned long flags;
 566         struct log_c *lc = log->context;
 567         LIST_HEAD(mark_list);
 568         LIST_HEAD(clear_list);
 569         int mark_list_is_empty;
 570         int clear_list_is_empty;
 571         struct dm_dirty_log_flush_entry *fe, *tmp_fe;
 572         mempool_t *flush_entry_pool = &lc->flush_entry_pool;
 573 
 574         spin_lock_irqsave(&lc->flush_lock, flags);
 575         list_splice_init(&lc->mark_list, &mark_list);
 576         list_splice_init(&lc->clear_list, &clear_list);
 577         spin_unlock_irqrestore(&lc->flush_lock, flags);
 578 
 579         mark_list_is_empty = list_empty(&mark_list);
 580         clear_list_is_empty = list_empty(&clear_list);
 581 
 582         if (mark_list_is_empty && clear_list_is_empty)
 583                 return 0;
 584 
 585         r = flush_by_group(lc, &clear_list, 0);
 586         if (r)
 587                 goto out;
 588 
 589         if (!lc->integrated_flush) {
 590                 r = flush_by_group(lc, &mark_list, 0);
 591                 if (r)
 592                         goto out;
 593                 r = userspace_do_request(lc, lc->uuid, DM_ULOG_FLUSH,
 594                                          NULL, 0, NULL, NULL);
 595                 goto out;
 596         }
 597 
 598         /*
 599          * Send integrated flush request with mark_list as payload.
 600          */
 601         r = flush_by_group(lc, &mark_list, 1);
 602         if (r)
 603                 goto out;
 604 
 605         if (mark_list_is_empty && !atomic_read(&lc->sched_flush)) {
 606                 /*
 607                  * When there are only clear region requests,
 608                  * we schedule a flush in the future.
 609                  */
 610                 queue_delayed_work(lc->dmlog_wq, &lc->flush_log_work, 3 * HZ);
 611                 atomic_set(&lc->sched_flush, 1);
 612         } else {
 613                 /*
 614                  * Cancel pending flush because we
 615                  * have already flushed in mark_region.
 616                  */
 617                 cancel_delayed_work(&lc->flush_log_work);
 618                 atomic_set(&lc->sched_flush, 0);
 619         }
 620 
 621 out:
 622         /*
 623          * We can safely remove these entries, even after failure.
 624          * Calling code will receive an error and will know that
 625          * the log facility has failed.
 626          */
 627         list_for_each_entry_safe(fe, tmp_fe, &mark_list, list) {
 628                 list_del(&fe->list);
 629                 mempool_free(fe, flush_entry_pool);
 630         }
 631         list_for_each_entry_safe(fe, tmp_fe, &clear_list, list) {
 632                 list_del(&fe->list);
 633                 mempool_free(fe, flush_entry_pool);
 634         }
 635 
 636         if (r)
 637                 dm_table_event(lc->ti->table);
 638 
 639         return r;
 640 }
 641 
 642 /*
 643  * userspace_mark_region
 644  *
 645  * This function should avoid blocking unless absolutely required.
 646  * (Memory allocation is valid for blocking.)
 647  */
 648 static void userspace_mark_region(struct dm_dirty_log *log, region_t region)
 649 {
 650         unsigned long flags;
 651         struct log_c *lc = log->context;
 652         struct dm_dirty_log_flush_entry *fe;
 653 
 654         /* Wait for an allocation, but _never_ fail */
 655         fe = mempool_alloc(&lc->flush_entry_pool, GFP_NOIO);
 656         BUG_ON(!fe);
 657 
 658         spin_lock_irqsave(&lc->flush_lock, flags);
 659         fe->type = DM_ULOG_MARK_REGION;
 660         fe->region = region;
 661         list_add(&fe->list, &lc->mark_list);
 662         spin_unlock_irqrestore(&lc->flush_lock, flags);
 663 
 664         return;
 665 }
 666 
 667 /*
 668  * userspace_clear_region
 669  *
 670  * This function must not block.
 671  * So, the alloc can't block.  In the worst case, it is ok to
 672  * fail.  It would simply mean we can't clear the region.
 673  * Does nothing to current sync context, but does mean
 674  * the region will be re-sync'ed on a reload of the mirror
 675  * even though it is in-sync.
 676  */
 677 static void userspace_clear_region(struct dm_dirty_log *log, region_t region)
 678 {
 679         unsigned long flags;
 680         struct log_c *lc = log->context;
 681         struct dm_dirty_log_flush_entry *fe;
 682 
 683         /*
 684          * If we fail to allocate, we skip the clearing of
 685          * the region.  This doesn't hurt us in any way, except
 686          * to cause the region to be resync'ed when the
 687          * device is activated next time.
 688          */
 689         fe = mempool_alloc(&lc->flush_entry_pool, GFP_ATOMIC);
 690         if (!fe) {
 691                 DMERR("Failed to allocate memory to clear region.");
 692                 return;
 693         }
 694 
 695         spin_lock_irqsave(&lc->flush_lock, flags);
 696         fe->type = DM_ULOG_CLEAR_REGION;
 697         fe->region = region;
 698         list_add(&fe->list, &lc->clear_list);
 699         spin_unlock_irqrestore(&lc->flush_lock, flags);
 700 
 701         return;
 702 }
 703 
 704 /*
 705  * userspace_get_resync_work
 706  *
 707  * Get a region that needs recovery.  It is valid to return
 708  * an error for this function.
 709  *
 710  * Returns: 1 if region filled, 0 if no work, <0 on error
 711  */
 712 static int userspace_get_resync_work(struct dm_dirty_log *log, region_t *region)
 713 {
 714         int r;
 715         size_t rdata_size;
 716         struct log_c *lc = log->context;
 717         struct {
 718                 int64_t i; /* 64-bit for mix arch compatibility */
 719                 region_t r;
 720         } pkg;
 721 
 722         if (lc->in_sync_hint >= lc->region_count)
 723                 return 0;
 724 
 725         rdata_size = sizeof(pkg);
 726         r = userspace_do_request(lc, lc->uuid, DM_ULOG_GET_RESYNC_WORK,
 727                                  NULL, 0, (char *)&pkg, &rdata_size);
 728 
 729         *region = pkg.r;
 730         return (r) ? r : (int)pkg.i;
 731 }
 732 
 733 /*
 734  * userspace_set_region_sync
 735  *
 736  * Set the sync status of a given region.  This function
 737  * must not fail.
 738  */
 739 static void userspace_set_region_sync(struct dm_dirty_log *log,
 740                                       region_t region, int in_sync)
 741 {
 742         struct log_c *lc = log->context;
 743         struct {
 744                 region_t r;
 745                 int64_t i;
 746         } pkg;
 747 
 748         pkg.r = region;
 749         pkg.i = (int64_t)in_sync;
 750 
 751         (void) userspace_do_request(lc, lc->uuid, DM_ULOG_SET_REGION_SYNC,
 752                                     (char *)&pkg, sizeof(pkg), NULL, NULL);
 753 
 754         /*
 755          * It would be nice to be able to report failures.
 756          * However, it is easy enough to detect and resolve.
 757          */
 758         return;
 759 }
 760 
 761 /*
 762  * userspace_get_sync_count
 763  *
 764  * If there is any sort of failure when consulting the server,
 765  * we assume that the sync count is zero.
 766  *
 767  * Returns: sync count on success, 0 on failure
 768  */
 769 static region_t userspace_get_sync_count(struct dm_dirty_log *log)
 770 {
 771         int r;
 772         size_t rdata_size;
 773         uint64_t sync_count;
 774         struct log_c *lc = log->context;
 775 
 776         rdata_size = sizeof(sync_count);
 777         r = userspace_do_request(lc, lc->uuid, DM_ULOG_GET_SYNC_COUNT,
 778                                  NULL, 0, (char *)&sync_count, &rdata_size);
 779 
 780         if (r)
 781                 return 0;
 782 
 783         if (sync_count >= lc->region_count)
 784                 lc->in_sync_hint = lc->region_count;
 785 
 786         return (region_t)sync_count;
 787 }
 788 
 789 /*
 790  * userspace_status
 791  *
 792  * Returns: amount of space consumed
 793  */
 794 static int userspace_status(struct dm_dirty_log *log, status_type_t status_type,
 795                             char *result, unsigned maxlen)
 796 {
 797         int r = 0;
 798         char *table_args;
 799         size_t sz = (size_t)maxlen;
 800         struct log_c *lc = log->context;
 801 
 802         switch (status_type) {
 803         case STATUSTYPE_INFO:
 804                 r = userspace_do_request(lc, lc->uuid, DM_ULOG_STATUS_INFO,
 805                                          NULL, 0, result, &sz);
 806 
 807                 if (r) {
 808                         sz = 0;
 809                         DMEMIT("%s 1 COM_FAILURE", log->type->name);
 810                 }
 811                 break;
 812         case STATUSTYPE_TABLE:
 813                 sz = 0;
 814                 table_args = strchr(lc->usr_argv_str, ' ');
 815                 BUG_ON(!table_args); /* There will always be a ' ' */
 816                 table_args++;
 817 
 818                 DMEMIT("%s %u %s ", log->type->name, lc->usr_argc, lc->uuid);
 819                 if (lc->integrated_flush)
 820                         DMEMIT("integrated_flush ");
 821                 DMEMIT("%s ", table_args);
 822                 break;
 823         }
 824         return (r) ? 0 : (int)sz;
 825 }
 826 
 827 /*
 828  * userspace_is_remote_recovering
 829  *
 830  * Returns: 1 if region recovering, 0 otherwise
 831  */
 832 static int userspace_is_remote_recovering(struct dm_dirty_log *log,
 833                                           region_t region)
 834 {
 835         int r;
 836         uint64_t region64 = region;
 837         struct log_c *lc = log->context;
 838         static unsigned long limit;
 839         struct {
 840                 int64_t is_recovering;
 841                 uint64_t in_sync_hint;
 842         } pkg;
 843         size_t rdata_size = sizeof(pkg);
 844 
 845         /*
 846          * Once the mirror has been reported to be in-sync,
 847          * it will never again ask for recovery work.  So,
 848          * we can safely say there is not a remote machine
 849          * recovering if the device is in-sync.  (in_sync_hint
 850          * must be reset at resume time.)
 851          */
 852         if (region < lc->in_sync_hint)
 853                 return 0;
 854         else if (time_after(limit, jiffies))
 855                 return 1;
 856 
 857         limit = jiffies + (HZ / 4);
 858         r = userspace_do_request(lc, lc->uuid, DM_ULOG_IS_REMOTE_RECOVERING,
 859                                  (char *)&region64, sizeof(region64),
 860                                  (char *)&pkg, &rdata_size);
 861         if (r)
 862                 return 1;
 863 
 864         lc->in_sync_hint = pkg.in_sync_hint;
 865 
 866         return (int)pkg.is_recovering;
 867 }
 868 
 869 static struct dm_dirty_log_type _userspace_type = {
 870         .name = "userspace",
 871         .module = THIS_MODULE,
 872         .ctr = userspace_ctr,
 873         .dtr = userspace_dtr,
 874         .presuspend = userspace_presuspend,
 875         .postsuspend = userspace_postsuspend,
 876         .resume = userspace_resume,
 877         .get_region_size = userspace_get_region_size,
 878         .is_clean = userspace_is_clean,
 879         .in_sync = userspace_in_sync,
 880         .flush = userspace_flush,
 881         .mark_region = userspace_mark_region,
 882         .clear_region = userspace_clear_region,
 883         .get_resync_work = userspace_get_resync_work,
 884         .set_region_sync = userspace_set_region_sync,
 885         .get_sync_count = userspace_get_sync_count,
 886         .status = userspace_status,
 887         .is_remote_recovering = userspace_is_remote_recovering,
 888 };
 889 
 890 static int __init userspace_dirty_log_init(void)
 891 {
 892         int r = 0;
 893 
 894         _flush_entry_cache = KMEM_CACHE(dm_dirty_log_flush_entry, 0);
 895         if (!_flush_entry_cache) {
 896                 DMWARN("Unable to create flush_entry_cache: No memory.");
 897                 return -ENOMEM;
 898         }
 899 
 900         r = dm_ulog_tfr_init();
 901         if (r) {
 902                 DMWARN("Unable to initialize userspace log communications");
 903                 kmem_cache_destroy(_flush_entry_cache);
 904                 return r;
 905         }
 906 
 907         r = dm_dirty_log_type_register(&_userspace_type);
 908         if (r) {
 909                 DMWARN("Couldn't register userspace dirty log type");
 910                 dm_ulog_tfr_exit();
 911                 kmem_cache_destroy(_flush_entry_cache);
 912                 return r;
 913         }
 914 
 915         DMINFO("version " DM_LOG_USERSPACE_VSN " loaded");
 916         return 0;
 917 }
 918 
 919 static void __exit userspace_dirty_log_exit(void)
 920 {
 921         dm_dirty_log_type_unregister(&_userspace_type);
 922         dm_ulog_tfr_exit();
 923         kmem_cache_destroy(_flush_entry_cache);
 924 
 925         DMINFO("version " DM_LOG_USERSPACE_VSN " unloaded");
 926         return;
 927 }
 928 
 929 module_init(userspace_dirty_log_init);
 930 module_exit(userspace_dirty_log_exit);
 931 
 932 MODULE_DESCRIPTION(DM_NAME " userspace dirty log link");
 933 MODULE_AUTHOR("Jonathan Brassow <dm-devel@redhat.com>");
 934 MODULE_LICENSE("GPL");