sys/vfs/hammer2/hammer2_synchro.c

   1 /*
   2  * Copyright (c) 2015-2018 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Matthew Dillon <dillon@dragonflybsd.org>
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  * 3. Neither the name of The DragonFly Project nor the names of its
  18  *    contributors may be used to endorse or promote products derived
  19  *    from this software without specific, prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34 /*
  35  * This module implements the cluster synchronizer.  Basically the way
  36  * it works is that a thread is created for each cluster node in a PFS.
  37  * This thread is responsible for synchronizing the current node using
  38  * data from other nodes.
  39  *
  40  * Any out of sync master or slave can get back into synchronization as
  41  * long as a quorum of masters agree on the update_tid.  If a quorum is
  42  * not available it may still be possible to synchronize to the highest
  43  * available update_tid as a way of trying to catch up as much as possible
  44  * until a quorum is available.
  45  *
  46  * If no quorum is possible (which can happen even if all masters are
  47  * available, if the update_tid does not match), then manual intervention
  48  * may be required to resolve discrepancies.
  49  */
  50 #include "hammer2.h"
  51
  52 typedef struct hammer2_deferred_ip {
  53         struct hammer2_deferred_ip *next;
  54         hammer2_inode_t *ip;
  55 } hammer2_deferred_ip_t;
  56
  57 typedef struct hammer2_deferred_list {
  58         hammer2_deferred_ip_t   *base;
  59         int                     count;
  60 } hammer2_deferred_list_t;
  61
  62
  63 #define HAMMER2_SYNCHRO_DEBUG 1
  64
  65 static int hammer2_sync_slaves(hammer2_thread_t *thr, hammer2_inode_t *ip,
  66                                 hammer2_deferred_list_t *list, int isroot);
  67 #if 0
  68 static void hammer2_update_pfs_status(hammer2_thread_t *thr, uint32_t flags);
  69                                 nerror = hammer2_sync_insert(
  70                                                 thr, &parent, &chain,
  71                                                 focus->bref.modify_tid,
  72                                                 idx, focus);
  73 #endif
  74 static int hammer2_sync_insert(hammer2_thread_t *thr,
  75                         hammer2_chain_t **parentp, hammer2_chain_t **chainp,
  76                         hammer2_tid_t modify_tid, int idx,
  77                         hammer2_chain_t *focus);
  78 static int hammer2_sync_destroy(hammer2_thread_t *thr,
  79                         hammer2_chain_t **parentp, hammer2_chain_t **chainp,
  80                         hammer2_tid_t mtid, int idx);
  81 static int hammer2_sync_replace(hammer2_thread_t *thr,
  82                         hammer2_chain_t *parent, hammer2_chain_t *chain,
  83                         hammer2_tid_t mtid, int idx,
  84                         hammer2_chain_t *focus, int isroot);
  85
  86 /****************************************************************************
  87  *                          HAMMER2 SYNC THREADS                            *
  88  ****************************************************************************/
  89 /*
  90  * Primary management thread for an element of a node.  A thread will exist
  91  * for each element requiring management.
  92  *
  93  * No management threads are needed for the SPMP or for any PMP with only
  94  * a single MASTER.
  95  *
  96  * On the SPMP - handles bulkfree and dedup operations
  97  * On a PFS    - handles remastering and synchronization
  98  */
  99 void
 100 hammer2_primary_sync_thread(void *arg)
 101 {
 102         hammer2_thread_t *thr = arg;
 103         hammer2_pfs_t *pmp;
 104         hammer2_deferred_list_t list;
 105         hammer2_deferred_ip_t *defer;
 106         int error;
 107         uint32_t flags;
 108         uint32_t nflags;
 109
 110         pmp = thr->pmp;
 111         bzero(&list, sizeof(list));
 112
 113         for (;;) {
 114                 flags = thr->flags;
 115                 cpu_ccfence();
 116
 117                 /*
 118                  * Handle stop request
 119                  */
 120                 if (flags & HAMMER2_THREAD_STOP)
 121                         break;
 122
 123                 /*
 124                  * Handle freeze request
 125                  */
 126                 if (flags & HAMMER2_THREAD_FREEZE) {
 127                         nflags = (flags & ~(HAMMER2_THREAD_FREEZE |
 128                                             HAMMER2_THREAD_WAITING)) |
 129                                  HAMMER2_THREAD_FROZEN;
 130                         if (!atomic_cmpset_int(&thr->flags, flags, nflags))
 131                                 continue;
 132                         if (flags & HAMMER2_THREAD_WAITING)
 133                                 wakeup(&thr->flags);
 134                         continue;
 135                 }
 136
 137                 if (flags & HAMMER2_THREAD_UNFREEZE) {
 138                         nflags = flags & ~(HAMMER2_THREAD_UNFREEZE |
 139                                            HAMMER2_THREAD_FROZEN |
 140                                            HAMMER2_THREAD_WAITING);
 141                         if (!atomic_cmpset_int(&thr->flags, flags, nflags))
 142                                 continue;
 143                         if (flags & HAMMER2_THREAD_WAITING)
 144                                 wakeup(&thr->flags);
 145                         continue;
 146                 }
 147
 148                 /*
 149                  * Force idle if frozen until unfrozen or stopped.
 150                  */
 151                 if (flags & HAMMER2_THREAD_FROZEN) {
 152                         nflags = flags | HAMMER2_THREAD_WAITING;
 153
 154                         tsleep_interlock(&thr->flags, 0);
 155                         if (atomic_cmpset_int(&thr->flags, flags, nflags))
 156                                 tsleep(&thr->flags, PINTERLOCKED, "frozen", 0);
 157                         continue;
 158                 }
 159
 160                 /*
 161                  * Reset state on REMASTER request
 162                  */
 163                 if (thr->flags & HAMMER2_THREAD_REMASTER) {
 164                         nflags = flags & ~HAMMER2_THREAD_REMASTER;
 165                         if (atomic_cmpset_int(&thr->flags, flags, nflags)) {
 166                                 /* reset state here */
 167                         }
 168                         continue;
 169                 }
 170
 171                 /*
 172                  * Synchronization scan.
 173                  */
 174                 if (hammer2_debug & 0x8000)
 175                         kprintf("sync_slaves pfs %s clindex %d\n",
 176                                 pmp->pfs_names[thr->clindex], thr->clindex);
 177                 hammer2_trans_init(pmp, 0);
 178
 179                 hammer2_inode_ref(pmp->iroot);
 180
 181                 for (;;) {
 182                         int didbreak = 0;
 183                         /* XXX lock synchronize pmp->modify_tid */
 184                         error = hammer2_sync_slaves(thr, pmp->iroot, &list, 1);
 185                         if (hammer2_debug & 0x8000) {
 186                                 kprintf("sync_slaves error %d defer %p\n",
 187                                         error, list.base);
 188                         }
 189                         if (error != HAMMER2_ERROR_EAGAIN)
 190                                 break;
 191                         while ((defer = list.base) != NULL) {
 192                                 hammer2_inode_t *nip;
 193
 194                                 nip = defer->ip;
 195                                 error = hammer2_sync_slaves(thr, nip, &list,
 196                                                         (nip == pmp->iroot));
 197                                 if (error &&
 198                                     error != HAMMER2_ERROR_EAGAIN &&
 199                                     error != HAMMER2_ERROR_ENOENT) {
 200                                         break;
 201                                 }
 202                                 if (hammer2_thr_break(thr)) {
 203                                         didbreak = 1;
 204                                         break;
 205                                 }
 206
 207                                 /*
 208                                  * If no additional defers occurred we can
 209                                  * remove this one, otherwise keep it on
 210                                  * the list and retry once the additional
 211                                  * defers have completed.
 212                                  */
 213                                 if (defer == list.base) {
 214                                         --list.count;
 215                                         list.base = defer->next;
 216                                         kfree(defer, M_HAMMER2);
 217                                         defer = NULL;   /* safety */
 218                                         hammer2_inode_drop(nip);
 219                                 }
 220                         }
 221
 222                         /*
 223                          * If the thread is being remastered, frozen, or
 224                          * stopped, clean up any left-over deferals.
 225                          */
 226                         if (didbreak ||
 227                             (error && error != HAMMER2_ERROR_EAGAIN)) {
 228                                 kprintf("didbreak\n");
 229                                 while ((defer = list.base) != NULL) {
 230                                         --list.count;
 231                                         hammer2_inode_drop(defer->ip);
 232                                         list.base = defer->next;
 233                                         kfree(defer, M_HAMMER2);
 234                                 }
 235                                 if (error == 0 || error == HAMMER2_ERROR_EAGAIN)
 236                                         error = HAMMER2_ERROR_EINPROGRESS;
 237                                 break;
 238                         }
 239                 }
 240
 241                 hammer2_inode_drop(pmp->iroot);
 242                 hammer2_trans_done(pmp);
 243
 244                 if (error && error != HAMMER2_ERROR_EINPROGRESS)
 245                         kprintf("hammer2_sync_slaves: error %d\n", error);
 246
 247                 /*
 248                  * Wait for event, or 5-second poll.
 249                  */
 250                 nflags = flags | HAMMER2_THREAD_WAITING;
 251                 tsleep_interlock(&thr->flags, 0);
 252                 if (atomic_cmpset_int(&thr->flags, flags, nflags)) {
 253                         tsleep(&thr->flags, 0, "h2idle", hz * 5);
 254                 }
 255         }
 256         thr->td = NULL;
 257         hammer2_thr_signal(thr, HAMMER2_THREAD_STOPPED);
 258         /* thr structure can go invalid after this point */
 259 }
 260
 261 #if 0
 262 /*
 263  * Given a locked cluster created from pmp->iroot, update the PFS's
 264  * reporting status.
 265  */
 266 static
 267 void
 268 hammer2_update_pfs_status(hammer2_thread_t *thr, uint32_t flags)
 269 {
 270         hammer2_pfs_t *pmp = thr->pmp;
 271
 272         flags &= HAMMER2_CLUSTER_ZFLAGS;
 273         if (pmp->cluster_flags == flags)
 274                 return;
 275         pmp->cluster_flags = flags;
 276
 277         kprintf("pfs %p", pmp);
 278         if (flags & HAMMER2_CLUSTER_MSYNCED)
 279                 kprintf(" masters-all-good");
 280         if (flags & HAMMER2_CLUSTER_SSYNCED)
 281                 kprintf(" slaves-all-good");
 282
 283         if (flags & HAMMER2_CLUSTER_WRHARD)
 284                 kprintf(" quorum/rw");
 285         else if (flags & HAMMER2_CLUSTER_RDHARD)
 286                 kprintf(" quorum/ro");
 287
 288         if (flags & HAMMER2_CLUSTER_UNHARD)
 289                 kprintf(" out-of-sync-masters");
 290         else if (flags & HAMMER2_CLUSTER_NOHARD)
 291                 kprintf(" no-masters-visible");
 292
 293         if (flags & HAMMER2_CLUSTER_WRSOFT)
 294                 kprintf(" soft/rw");
 295         else if (flags & HAMMER2_CLUSTER_RDSOFT)
 296                 kprintf(" soft/ro");
 297
 298         if (flags & HAMMER2_CLUSTER_UNSOFT)
 299                 kprintf(" out-of-sync-slaves");
 300         else if (flags & HAMMER2_CLUSTER_NOSOFT)
 301                 kprintf(" no-slaves-visible");
 302         kprintf("\n");
 303 }
 304 #endif
 305
 306 #if 0
 307 static
 308 void
 309 dumpcluster(const char *label,
 310             hammer2_cluster_t *cparent, hammer2_cluster_t *cluster)
 311 {
 312         hammer2_chain_t *chain;
 313         int i;
 314
 315         if ((hammer2_debug & 1) == 0)
 316                 return;
 317
 318         kprintf("%s\t", label);
 319         KKASSERT(cparent->nchains == cluster->nchains);
 320         for (i = 0; i < cparent->nchains; ++i) {
 321                 if (i)
 322                         kprintf("\t");
 323                 kprintf("%d ", i);
 324                 if ((chain = cparent->array[i].chain) != NULL) {
 325                         kprintf("%016jx%s ",
 326                                 chain->bref.key,
 327                                 ((cparent->array[i].flags &
 328                                   HAMMER2_CITEM_INVALID) ? "(I)" : "   ")
 329                         );
 330                 } else {
 331                         kprintf("      NULL      %s ", "   ");
 332                 }
 333                 if ((chain = cluster->array[i].chain) != NULL) {
 334                         kprintf("%016jx%s ",
 335                                 chain->bref.key,
 336                                 ((cluster->array[i].flags &
 337                                   HAMMER2_CITEM_INVALID) ? "(I)" : "   ")
 338                         );
 339                 } else {
 340                         kprintf("      NULL      %s ", "   ");
 341                 }
 342                 kprintf("\n");
 343         }
 344 }
 345 #endif
 346
 347 /*
 348  * Each out of sync node sync-thread must issue an all-nodes XOP scan of
 349  * the inode.  This creates a multiplication effect since the XOP scan itself
 350  * issues to all nodes.  However, this is the only way we can safely
 351  * synchronize nodes which might have disparate I/O bandwidths and the only
 352  * way we can safely deal with stalled nodes.
 353  *
 354  * XXX serror / merror rollup and handling.
 355  */
 356 static
 357 int
 358 hammer2_sync_slaves(hammer2_thread_t *thr, hammer2_inode_t *ip,
 359                     hammer2_deferred_list_t *list, int isroot)
 360 {
 361         hammer2_xop_scanall_t *xop;
 362         hammer2_chain_t *parent;
 363         hammer2_chain_t *chain;
 364         hammer2_pfs_t *pmp;
 365         hammer2_key_t key_next;
 366         hammer2_tid_t sync_tid;
 367         int needrescan;
 368         int want_update;
 369         int serror;             /* slave error */
 370         int merror;             /* master error (from xop_collect) */
 371         int nerror;             /* temporary error */
 372         int idx;
 373         int n;
 374
 375         pmp = ip->pmp;
 376         idx = thr->clindex;     /* cluster node we are responsible for */
 377         needrescan = 0;
 378         want_update = 0;
 379         sync_tid = 0;
 380         chain = NULL;
 381         parent = NULL;
 382
 383 #if 0
 384         /*
 385          * Nothing to do if all slaves are synchronized.
 386          * Nothing to do if cluster not authoritatively readable.
 387          */
 388         if (pmp->cluster_flags & HAMMER2_CLUSTER_SSYNCED)
 389                 return(0);
 390         if ((pmp->cluster_flags & HAMMER2_CLUSTER_RDHARD) == 0)
 391                 return(HAMMER2_ERROR_INCOMPLETE);
 392 #endif
 393
 394         merror = 0;
 395
 396         /*
 397          * Resolve the root inode of the PFS and determine if synchronization
 398          * is needed by checking modify_tid.
 399          *
 400          * Retain the synchronization TID from the focus inode and use it
 401          * later to synchronize the focus inode if/when the recursion
 402          * succeeds.
 403          */
 404         {
 405                 hammer2_xop_ipcluster_t *xop2;
 406                 hammer2_chain_t *focus;
 407
 408                 hammer2_inode_lock(ip, HAMMER2_RESOLVE_SHARED);
 409                 xop2 = hammer2_xop_alloc(ip, HAMMER2_XOP_MODIFYING);
 410                 hammer2_xop_start_except(&xop2->head, hammer2_xop_ipcluster,
 411                                          idx);
 412                 hammer2_inode_unlock(ip);
 413                 merror = hammer2_xop_collect(&xop2->head, 0);
 414                 if (merror == 0 && (focus = xop2->head.cluster.focus) != NULL) {
 415                         sync_tid = focus->bref.modify_tid;
 416                         chain = hammer2_inode_chain_and_parent(ip, idx,
 417                                                     &parent,
 418                                                     HAMMER2_RESOLVE_ALWAYS |
 419                                                     HAMMER2_RESOLVE_SHARED);
 420                         want_update = (chain->bref.modify_tid != sync_tid);
 421                         if (chain) {
 422                                 hammer2_chain_unlock(chain);
 423                                 hammer2_chain_drop(chain);
 424                                 chain = NULL;
 425                         }
 426                         if (parent) {
 427                                 hammer2_chain_unlock(parent);
 428                                 hammer2_chain_drop(parent);
 429                                 parent = NULL;
 430                         }
 431                 }
 432                 hammer2_xop_retire(&xop2->head, HAMMER2_XOPMASK_VOP);
 433         }
 434
 435         if (want_update == 0)
 436                 return(0);
 437
 438         /*
 439          * The inode is left unlocked during the scan.  Issue a XOP
 440          * that does *not* include our cluster index to iterate
 441          * properly synchronized elements and resolve our cluster index
 442          * against it.
 443          */
 444         hammer2_inode_lock(ip, HAMMER2_RESOLVE_SHARED);
 445         xop = hammer2_xop_alloc(ip, HAMMER2_XOP_MODIFYING);
 446         xop->key_beg = HAMMER2_KEY_MIN;
 447         xop->key_end = HAMMER2_KEY_MAX;
 448         xop->resolve_flags = HAMMER2_RESOLVE_SHARED |
 449                              HAMMER2_RESOLVE_ALWAYS;
 450         xop->lookup_flags = HAMMER2_LOOKUP_SHARED |
 451                             HAMMER2_LOOKUP_NODIRECT |
 452                             HAMMER2_LOOKUP_ALWAYS;
 453         hammer2_xop_start_except(&xop->head, hammer2_xop_scanall, idx);
 454         parent = hammer2_inode_chain(ip, idx,
 455                                      HAMMER2_RESOLVE_ALWAYS |
 456                                      HAMMER2_RESOLVE_SHARED);
 457         hammer2_inode_unlock(ip);
 458
 459         chain = hammer2_chain_lookup(&parent, &key_next,
 460                                      HAMMER2_KEY_MIN, HAMMER2_KEY_MAX,
 461                                      &serror,
 462                                      HAMMER2_LOOKUP_SHARED |
 463                                      HAMMER2_LOOKUP_NODIRECT |
 464                                      HAMMER2_LOOKUP_NODATA);
 465         merror = hammer2_xop_collect(&xop->head, 0);
 466         if (hammer2_debug & 0x8000) {
 467                 kprintf("START_SCAN IP=%016jx chain=%p (%016jx)\n",
 468                         ip->meta.name_key, chain,
 469                         (chain ? chain->bref.key : -1));
 470         }
 471
 472         for (;;) {
 473                 /*
 474                  * We are done if our scan is done and the XOP scan is done.
 475                  * We are done if the XOP scan failed (that is, we don't
 476                  * have authoritative data to synchronize with).
 477                  */
 478                 int advance_local = 0;
 479                 int advance_xop = 0;
 480                 int dodefer = 0;
 481                 hammer2_chain_t *focus;
 482
 483                 if (chain == NULL && merror == HAMMER2_ERROR_ENOENT)
 484                         break;
 485                 if (merror && merror != HAMMER2_ERROR_ENOENT)
 486                         break;
 487
 488                 /*
 489                  * Compare
 490                  */
 491                 if (chain && merror == HAMMER2_ERROR_ENOENT) {
 492                         /*
 493                          * If we have local chains but the XOP scan is done,
 494                          * the chains need to be deleted.
 495                          */
 496                         n = -1;
 497                         focus = NULL;
 498                 } else if (chain == NULL) {
 499                         /*
 500                          * If our local scan is done but the XOP scan is not,
 501                          * we need to create the missing chain(s).
 502                          */
 503                         n = 1;
 504                         focus = xop->head.cluster.focus;
 505                 } else {
 506                         /*
 507                          * Otherwise compare to determine the action
 508                          * needed.
 509                          */
 510                         focus = xop->head.cluster.focus;
 511                         n = hammer2_chain_cmp(chain, focus);
 512                 }
 513
 514                 /*
 515                  * Take action based on comparison results.
 516                  */
 517                 if (n < 0) {
 518                         /*
 519                          * Delete extranious local data.  This will
 520                          * automatically advance the chain.
 521                          */
 522                         nerror = hammer2_sync_destroy(thr, &parent, &chain,
 523                                                       0, idx);
 524                 } else if (n == 0 && chain->bref.modify_tid !=
 525                                      focus->bref.modify_tid) {
 526                         /*
 527                          * Matching key but local data or meta-data requires
 528                          * updating.  If we will recurse, we still need to
 529                          * update to compatible content first but we do not
 530                          * synchronize modify_tid until the entire recursion
 531                          * has completed successfully.
 532                          */
 533                         if (focus->bref.type == HAMMER2_BREF_TYPE_INODE) {
 534                                 nerror = hammer2_sync_replace(
 535                                                 thr, parent, chain,
 536                                                 0,
 537                                                 idx, focus, 0);
 538                                 dodefer = 1;
 539                         } else {
 540                                 nerror = hammer2_sync_replace(
 541                                                 thr, parent, chain,
 542                                                 focus->bref.modify_tid,
 543                                                 idx, focus, 0);
 544                         }
 545                         advance_local = 1;
 546                         advance_xop = 1;
 547                 } else if (n == 0) {
 548                         /*
 549                          * 100% match, advance both
 550                          */
 551                         advance_local = 1;
 552                         advance_xop = 1;
 553                         nerror = 0;
 554                 } else if (n > 0) {
 555                         /*
 556                          * Insert missing local data.
 557                          *
 558                          * If we will recurse, we still need to update to
 559                          * compatible content first but we do not synchronize
 560                          * modify_tid until the entire recursion has
 561                          * completed successfully.
 562                          */
 563                         if (focus->bref.type == HAMMER2_BREF_TYPE_INODE) {
 564                                 nerror = hammer2_sync_insert(
 565                                                 thr, &parent, &chain,
 566                                                 0,
 567                                                 idx, focus);
 568                                 dodefer = 2;
 569                         } else {
 570                                 nerror = hammer2_sync_insert(
 571                                                 thr, &parent, &chain,
 572                                                 focus->bref.modify_tid,
 573                                                 idx, focus);
 574                         }
 575                         advance_local = 1;
 576                         advance_xop = 1;
 577                 }
 578
 579                 /*
 580                  * We cannot recurse depth-first because the XOP is still
 581                  * running in node threads for this scan.  Create a placemarker
 582                  * by obtaining and record the hammer2_inode.
 583                  *
 584                  * We excluded our node from the XOP so we must temporarily
 585                  * add it to xop->head.cluster so it is properly incorporated
 586                  * into the inode.
 587                  *
 588                  * The deferral is pushed onto a LIFO list for bottom-up
 589                  * synchronization.
 590                  */
 591                 if (merror == 0 && dodefer) {
 592                         hammer2_inode_t *nip;
 593                         hammer2_deferred_ip_t *defer;
 594
 595                         KKASSERT(focus->bref.type == HAMMER2_BREF_TYPE_INODE);
 596
 597                         defer = kmalloc(sizeof(*defer), M_HAMMER2,
 598                                         M_WAITOK | M_ZERO);
 599                         KKASSERT(xop->head.cluster.array[idx].chain == NULL);
 600                         xop->head.cluster.array[idx].flags =
 601                                                         HAMMER2_CITEM_INVALID;
 602                         xop->head.cluster.array[idx].chain = chain;
 603                         nip = hammer2_inode_get(pmp, ip,
 604                                                 &xop->head.cluster, idx);
 605                         xop->head.cluster.array[idx].chain = NULL;
 606
 607                         hammer2_inode_ref(nip);
 608                         hammer2_inode_unlock(nip);
 609
 610                         defer->next = list->base;
 611                         defer->ip = nip;
 612                         list->base = defer;
 613                         ++list->count;
 614                         needrescan = 1;
 615                 }
 616
 617                 /*
 618                  * If at least one deferral was added and the deferral
 619                  * list has grown too large, stop adding more.  This
 620                  * will trigger an HAMMER2_ERROR_EAGAIN return.
 621                  */
 622                 if (needrescan && list->count > 1000)
 623                         break;
 624
 625                 /*
 626                  * Advancements for iteration.
 627                  */
 628                 if (advance_xop) {
 629                         merror = hammer2_xop_collect(&xop->head, 0);
 630                 }
 631                 if (advance_local) {
 632                         chain = hammer2_chain_next(&parent, chain, &key_next,
 633                                                    key_next, HAMMER2_KEY_MAX,
 634                                                    &serror,
 635                                                    HAMMER2_LOOKUP_SHARED |
 636                                                    HAMMER2_LOOKUP_NODIRECT |
 637                                                    HAMMER2_LOOKUP_NODATA);
 638                 }
 639         }
 640         hammer2_xop_retire(&xop->head, HAMMER2_XOPMASK_VOP);
 641         if (chain) {
 642                 hammer2_chain_unlock(chain);
 643                 hammer2_chain_drop(chain);
 644         }
 645         if (parent) {
 646                 hammer2_chain_unlock(parent);
 647                 hammer2_chain_drop(parent);
 648         }
 649
 650         /*
 651          * If we added deferrals we want the caller to synchronize them
 652          * and then call us again.
 653          *
 654          * NOTE: In this situation we do not yet want to synchronize our
 655          *       inode, setting the error code also has that effect.
 656          */
 657         if ((merror == 0 || merror == HAMMER2_ERROR_ENOENT) && needrescan)
 658                 merror = HAMMER2_ERROR_EAGAIN;
 659
 660         /*
 661          * If no error occurred we can synchronize the inode meta-data
 662          * and modify_tid.  Only limited changes are made to PFSROOTs.
 663          *
 664          * XXX inode lock was lost
 665          */
 666         if (merror == 0 || merror == HAMMER2_ERROR_ENOENT) {
 667                 hammer2_xop_ipcluster_t *xop2;
 668                 hammer2_chain_t *focus;
 669
 670                 hammer2_inode_lock(ip, HAMMER2_RESOLVE_SHARED);
 671                 xop2 = hammer2_xop_alloc(ip, HAMMER2_XOP_MODIFYING);
 672                 hammer2_xop_start_except(&xop2->head, hammer2_xop_ipcluster,
 673                                          idx);
 674                 hammer2_inode_unlock(ip);
 675                 merror = hammer2_xop_collect(&xop2->head, 0);
 676                 if (merror == 0) {
 677                         focus = xop2->head.cluster.focus;
 678                         if (hammer2_debug & 0x8000) {
 679                                 kprintf("syncthr: update inode %p (%s)\n",
 680                                         focus,
 681                                         (focus ? (char *)focus->data->
 682                                                          ipdata.filename :
 683                                                  "?"));
 684                         }
 685                         chain = hammer2_inode_chain_and_parent(ip, idx,
 686                                                     &parent,
 687                                                     HAMMER2_RESOLVE_ALWAYS |
 688                                                     HAMMER2_RESOLVE_SHARED);
 689
 690                         KKASSERT(parent != NULL);
 691                         nerror = hammer2_sync_replace(
 692                                         thr, parent, chain,
 693                                         sync_tid,
 694                                         idx, focus, isroot);
 695                         hammer2_chain_unlock(chain);
 696                         hammer2_chain_drop(chain);
 697                         hammer2_chain_unlock(parent);
 698                         hammer2_chain_drop(parent);
 699                         /* XXX */
 700                 }
 701                 hammer2_xop_retire(&xop2->head, HAMMER2_XOPMASK_VOP);
 702         }
 703
 704         return merror;
 705 }
 706
 707 /*
 708  * Create a missing chain by copying the focus from another device.
 709  *
 710  * On entry *parentp and focus are both locked shared.  The chain will be
 711  * created and returned in *chainp also locked shared.
 712  */
 713 static
 714 int
 715 hammer2_sync_insert(hammer2_thread_t *thr,
 716                     hammer2_chain_t **parentp, hammer2_chain_t **chainp,
 717                     hammer2_tid_t mtid, int idx, hammer2_chain_t *focus)
 718 {
 719         hammer2_chain_t *chain;
 720         hammer2_key_t dummy;
 721         int error;
 722
 723 #if HAMMER2_SYNCHRO_DEBUG
 724         if (hammer2_debug & 1)
 725         kprintf("insert rec par=%p/%d.%016jx slave %d %d.%016jx mod=%016jx\n",
 726                 *parentp,
 727                 (*parentp)->bref.type,
 728                 (*parentp)->bref.key,
 729                 idx,
 730                 focus->bref.type, focus->bref.key, mtid);
 731 #endif
 732
 733         /*
 734          * Parent requires an exclusive lock for the insertion.
 735          * We must unlock the child to avoid deadlocks while
 736          * relocking the parent.
 737          */
 738         if (*chainp) {
 739                 hammer2_chain_unlock(*chainp);
 740                 hammer2_chain_drop(*chainp);
 741                 *chainp = NULL;
 742         }
 743         hammer2_chain_unlock(*parentp);
 744         hammer2_chain_lock(*parentp, HAMMER2_RESOLVE_ALWAYS);
 745
 746         /*
 747          * We must reissue the lookup to properly position (*parentp)
 748          * for the insertion.
 749          */
 750         chain = hammer2_chain_lookup(parentp, &dummy,
 751                                      focus->bref.key, focus->bref.key,
 752                                      &error,
 753                                      HAMMER2_LOOKUP_NODIRECT |
 754                                      HAMMER2_LOOKUP_ALWAYS);
 755         KKASSERT(chain == NULL);
 756
 757         chain = NULL;
 758         error = hammer2_chain_create(parentp, &chain,
 759                                      thr->pmp, focus->bref.methods,
 760                                      focus->bref.key, focus->bref.keybits,
 761                                      focus->bref.type, focus->bytes,
 762                                      mtid, 0, 0);
 763         if (error == 0) {
 764                 error = hammer2_chain_modify(chain, mtid, 0, 0);
 765                 if (error)
 766                         goto failed;
 767
 768                 /*
 769                  * Copy focus to new chain
 770                  */
 771
 772                 /* type already set */
 773                 chain->bref.methods = focus->bref.methods;
 774                 /* keybits already set */
 775                 chain->bref.vradix = focus->bref.vradix;
 776                 /* mirror_tid set by flush */
 777                 KKASSERT(chain->bref.modify_tid == mtid);
 778                 chain->bref.flags = focus->bref.flags;
 779                 /* key already present */
 780                 /* check code will be recalculated */
 781
 782                 /*
 783                  * Copy data body.
 784                  */
 785                 switch(chain->bref.type) {
 786                 case HAMMER2_BREF_TYPE_INODE:
 787                         if ((focus->data->ipdata.meta.op_flags &
 788                              HAMMER2_OPFLAG_DIRECTDATA) == 0) {
 789                                 /* do not copy block table */
 790                                 bcopy(focus->data, chain->data,
 791                                       offsetof(hammer2_inode_data_t, u));
 792                                 break;
 793                         }
 794                         /* fall through copy whole thing */
 795                 case HAMMER2_BREF_TYPE_DATA:
 796                         bcopy(focus->data, chain->data, chain->bytes);
 797                         hammer2_chain_setcheck(chain, chain->data);
 798                         break;
 799                 case HAMMER2_BREF_TYPE_DIRENT:
 800                         /*
 801                          * Directory entries embed data in the blockref.
 802                          */
 803                         if (chain->bytes) {
 804                                 bcopy(focus->data, chain->data, chain->bytes);
 805                                 hammer2_chain_setcheck(chain, chain->data);
 806                         } else {
 807                                 chain->bref.check = focus->bref.check;
 808                         }
 809                         chain->bref.embed = focus->bref.embed;
 810                         break;
 811                 default:
 812                         KKASSERT(0);
 813                         break;
 814                 }
 815         }
 816
 817 failed:
 818         if (chain)
 819                 hammer2_chain_unlock(chain);    /* unlock, leave ref */
 820         *chainp = chain;                        /* will be returned locked */
 821
 822         /*
 823          * Avoid an ordering deadlock when relocking shared.
 824          */
 825         hammer2_chain_unlock(*parentp);
 826         hammer2_chain_lock(*parentp, HAMMER2_RESOLVE_SHARED |
 827                                      HAMMER2_RESOLVE_ALWAYS);
 828         if (chain) {
 829                 hammer2_chain_lock(chain, HAMMER2_RESOLVE_SHARED |
 830                                           HAMMER2_RESOLVE_ALWAYS);
 831                 error = chain->error;
 832         }
 833
 834         return error;
 835 }
 836
 837 /*
 838  * Destroy an extranious chain.
 839  *
 840  * Both *parentp and *chainp are locked shared.
 841  *
 842  * On return, *chainp will be adjusted to point to the next element in the
 843  * iteration and locked shared.
 844  */
 845 static
 846 int
 847 hammer2_sync_destroy(hammer2_thread_t *thr,
 848                      hammer2_chain_t **parentp, hammer2_chain_t **chainp,
 849                      hammer2_tid_t mtid, int idx)
 850 {
 851         hammer2_chain_t *chain;
 852         hammer2_key_t key_next;
 853         hammer2_key_t save_key;
 854         int error;
 855
 856         chain = *chainp;
 857
 858 #if HAMMER2_SYNCHRO_DEBUG
 859         if (hammer2_debug & 1)
 860         kprintf("destroy rec %p/%p slave %d %d.%016jx\n",
 861                 *parentp, chain,
 862                 idx, chain->bref.type, chain->bref.key);
 863 #endif
 864
 865         save_key = chain->bref.key;
 866         if (save_key != HAMMER2_KEY_MAX)
 867                 ++save_key;
 868
 869         /*
 870          * Try to avoid unnecessary I/O.
 871          *
 872          * XXX accounting not propagated up properly.  We might have to do
 873          *     a RESOLVE_MAYBE here and pass 0 for the flags.
 874          */
 875         hammer2_chain_unlock(chain);    /* relock exclusive */
 876         hammer2_chain_unlock(*parentp);
 877         hammer2_chain_lock(*parentp, HAMMER2_RESOLVE_ALWAYS);
 878         hammer2_chain_lock(chain, HAMMER2_RESOLVE_NEVER);
 879
 880         hammer2_chain_delete(*parentp, chain, mtid, HAMMER2_DELETE_PERMANENT);
 881         hammer2_chain_unlock(chain);
 882         hammer2_chain_drop(chain);
 883         chain = NULL;                   /* safety */
 884
 885         hammer2_chain_unlock(*parentp); /* relock shared */
 886         hammer2_chain_lock(*parentp, HAMMER2_RESOLVE_SHARED |
 887                                      HAMMER2_RESOLVE_ALWAYS);
 888         *chainp = hammer2_chain_lookup(parentp, &key_next,
 889                                      save_key, HAMMER2_KEY_MAX,
 890                                      &error,
 891                                      HAMMER2_LOOKUP_SHARED |
 892                                      HAMMER2_LOOKUP_NODIRECT |
 893                                      HAMMER2_LOOKUP_NODATA);
 894         return error;
 895 }
 896
 897 /*
 898  * cparent is locked exclusively, with an extra ref, cluster is not locked.
 899  * Replace element [i] in the cluster.
 900  */
 901 static
 902 int
 903 hammer2_sync_replace(hammer2_thread_t *thr,
 904                      hammer2_chain_t *parent, hammer2_chain_t *chain,
 905                      hammer2_tid_t mtid, int idx,
 906                      hammer2_chain_t *focus, int isroot)
 907 {
 908         uint8_t otype;
 909         int nradix;
 910         int error;
 911
 912 #if HAMMER2_SYNCHRO_DEBUG
 913         if (hammer2_debug & 1)
 914         kprintf("replace rec %p slave %d %d.%016jx mod=%016jx\n",
 915                 chain,
 916                 idx,
 917                 focus->bref.type, focus->bref.key, mtid);
 918 #endif
 919         hammer2_chain_unlock(chain);
 920         hammer2_chain_lock(chain, HAMMER2_RESOLVE_ALWAYS);
 921         error = chain->error;
 922         if (error == 0) {
 923                 if (chain->bytes != focus->bytes) {
 924                         /* XXX what if compressed? */
 925                         nradix = hammer2_getradix(chain->bytes);
 926                         error = hammer2_chain_resize(chain, mtid, 0, nradix, 0);
 927                         if (error)
 928                                 goto failed;
 929                 }
 930                 error = hammer2_chain_modify(chain, mtid, 0, 0);
 931                 if (error)
 932                         goto failed;
 933                 otype = chain->bref.type;
 934                 chain->bref.type = focus->bref.type;
 935                 chain->bref.methods = focus->bref.methods;
 936                 chain->bref.keybits = focus->bref.keybits;
 937                 chain->bref.vradix = focus->bref.vradix;
 938                 /* mirror_tid updated by flush */
 939                 KKASSERT(mtid == 0 || chain->bref.modify_tid == mtid);
 940                 chain->bref.flags = focus->bref.flags;
 941                 /* key already present */
 942                 /* check code will be recalculated */
 943
 944                 /*
 945                  * Copy data body.
 946                  */
 947                 switch(chain->bref.type) {
 948                 case HAMMER2_BREF_TYPE_INODE:
 949                         /*
 950                          * Special case PFSROOTs, only limited changes can
 951                          * be made since the meta-data contains miscellanious
 952                          * distinguishing fields.
 953                          */
 954                         if (isroot) {
 955                                 chain->data->ipdata.meta.uflags =
 956                                         focus->data->ipdata.meta.uflags;
 957                                 chain->data->ipdata.meta.rmajor =
 958                                         focus->data->ipdata.meta.rmajor;
 959                                 chain->data->ipdata.meta.rminor =
 960                                         focus->data->ipdata.meta.rminor;
 961                                 chain->data->ipdata.meta.ctime =
 962                                         focus->data->ipdata.meta.ctime;
 963                                 chain->data->ipdata.meta.mtime =
 964                                         focus->data->ipdata.meta.mtime;
 965                                 chain->data->ipdata.meta.atime =
 966                                         focus->data->ipdata.meta.atime;
 967                                 /* not btime */
 968                                 chain->data->ipdata.meta.uid =
 969                                         focus->data->ipdata.meta.uid;
 970                                 chain->data->ipdata.meta.gid =
 971                                         focus->data->ipdata.meta.gid;
 972                                 chain->data->ipdata.meta.mode =
 973                                         focus->data->ipdata.meta.mode;
 974                                 chain->data->ipdata.meta.ncopies =
 975                                         focus->data->ipdata.meta.ncopies;
 976                                 chain->data->ipdata.meta.comp_algo =
 977                                         focus->data->ipdata.meta.comp_algo;
 978                                 chain->data->ipdata.meta.check_algo =
 979                                         focus->data->ipdata.meta.check_algo;
 980                                 chain->data->ipdata.meta.data_quota =
 981                                         focus->data->ipdata.meta.data_quota;
 982                                 chain->data->ipdata.meta.inode_quota =
 983                                         focus->data->ipdata.meta.inode_quota;
 984
 985                                 /*
 986                                  * last snapshot tid controls overwrite
 987                                  */
 988                                 if (chain->data->ipdata.meta.pfs_lsnap_tid <
 989                                     focus->data->ipdata.meta.pfs_lsnap_tid) {
 990                                         chain->data->ipdata.meta.pfs_lsnap_tid =
 991                                         focus->data->ipdata.meta.pfs_lsnap_tid;
 992                                 }
 993
 994                                 hammer2_chain_setcheck(chain, chain->data);
 995                                 break;
 996                         }
 997
 998                         /*
 999                          * Normal replacement.
1000                          */
1001                         if ((focus->data->ipdata.meta.op_flags &
1002                              HAMMER2_OPFLAG_DIRECTDATA) == 0) {
1003                                 /*
1004                                  * If DIRECTDATA is transitioning to 0 or the
1005                                  * old chain is not an inode we have to
1006                                  * initialize the block table.
1007                                  */
1008                                 if (otype != HAMMER2_BREF_TYPE_INODE ||
1009                                     (chain->data->ipdata.meta.op_flags &
1010                                      HAMMER2_OPFLAG_DIRECTDATA)) {
1011                                         kprintf("chain inode trans "
1012                                                 "away from dd\n");
1013                                         bzero(&chain->data->ipdata.u,
1014                                               sizeof(chain->data->ipdata.u));
1015                                 }
1016                                 bcopy(focus->data, chain->data,
1017                                       offsetof(hammer2_inode_data_t, u));
1018                                 /* XXX setcheck on inode should not be needed */
1019                                 hammer2_chain_setcheck(chain, chain->data);
1020                                 break;
1021                         }
1022                         /* fall through */
1023                 case HAMMER2_BREF_TYPE_DATA:
1024                         bcopy(focus->data, chain->data, chain->bytes);
1025                         hammer2_chain_setcheck(chain, chain->data);
1026                         break;
1027                 case HAMMER2_BREF_TYPE_DIRENT:
1028                         /*
1029                          * Directory entries embed data in the blockref.
1030                          */
1031                         if (chain->bytes) {
1032                                 bcopy(focus->data, chain->data, chain->bytes);
1033                                 hammer2_chain_setcheck(chain, chain->data);
1034                         } else {
1035                                 chain->bref.check = focus->bref.check;
1036                         }
1037                         chain->bref.embed = focus->bref.embed;
1038                         break;
1039                 default:
1040                         KKASSERT(0);
1041                         break;
1042                 }
1043         }
1044
1045 failed:
1046         hammer2_chain_unlock(chain);
1047         hammer2_chain_lock(chain, HAMMER2_RESOLVE_SHARED |
1048                                   HAMMER2_RESOLVE_MAYBE);
1049
1050         return error;
1051 }