sys/vfs/hammer2/hammer2_cluster.c

   1 /*
   2  * Copyright (c) 2013-2015 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  * The cluster module collects multiple chains representing the same
  36  * information from different nodes into a single entity.  It allows direct
  37  * access to media data as long as it is not blockref array data (which
  38  * will obviously have to be different at each node).
  39  *
  40  * This module also handles I/O dispatch, status rollup, and various
  41  * mastership arrangements including quorum operations.  It effectively
  42  * presents one topology to the vnops layer.
  43  *
  44  * Many of the API calls mimic chain API calls but operate on clusters
  45  * instead of chains.  Please see hammer2_chain.c for more complete code
  46  * documentation of the API functions.
  47  *
  48  * WARNING! This module is *extremely* complex.  It must issue asynchronous
  49  *          locks and I/O, do quorum and/or master-slave processing, and
  50  *          it must operate properly even if some nodes are broken (which
  51  *          can also mean indefinite locks).
  52  *
  53  *                              CLUSTER OPERATIONS
  54  *
  55  * Cluster operations can be broken down into three pieces:
  56  *
  57  * (1) Chain locking and data retrieval.
  58  *
  59  *      - Most complex functions, quorum management on transaction ids.
  60  *
  61  *      - Locking and data accesses must be internally asynchronous.
  62  *
  63  *      - Validate and manage cache coherency primitives (cache state
  64  *        is stored in chain topologies but must be validated by these
  65  *        functions).
  66  *
  67  * (2) Lookups and Scans
  68  *              hammer2_cluster_lookup()
  69  *              hammer2_cluster_next()
  70  *
  71  *      - Depend on locking & data retrieval functions, but still complex.
  72  *
  73  *      - Must do quorum management on transaction ids.
  74  *
  75  *      - Lookup and Iteration ops Must be internally asynchronous.
  76  *
  77  * (3) Modifying Operations
  78  *              hammer2_cluster_create()
  79  *
  80  *      - Can usually punt on failures, operation continues unless quorum
  81  *        is lost.  If quorum is lost, must wait for resynchronization
  82  *        (depending on the management mode).
  83  *
  84  *      - Must disconnect node on failures (also not flush), remount, and
  85  *        resynchronize.
  86  *
  87  *      - Network links (via kdmsg) are relatively easy to issue as the
  88  *        complex underworkings of hammer2_chain.c don't have to messed
  89  *        with (the protocol is at a higher level than block-level).
  90  *
  91  *      - Multiple local disk nodes (i.e. block devices) are another matter.
  92  *        Chain operations have to be dispatched to per-node threads (xN)
  93  *        because we can't asynchronize potentially very complex chain
  94  *        operations in hammer2_chain.c (it would be a huge mess).
  95  *
  96  *        (these threads are also used to terminate incoming kdmsg ops from
  97  *        other machines).
  98  *
  99  *      - Single-node filesystems do not use threads and will simply call
 100  *        hammer2_chain.c functions directly.  This short-cut is handled
 101  *        at the base of each cluster function.
 102  */
 103 #include <sys/cdefs.h>
 104 #include <sys/param.h>
 105 #include <sys/systm.h>
 106 #include <sys/types.h>
 107 #include <sys/lock.h>
 108 #include <sys/uuid.h>
 109
 110 #include "hammer2.h"
 111
 112 /*
 113  * Returns the bref type of the cluster's foucs.
 114  *
 115  * If the cluster is errored, returns HAMMER2_BREF_TYPE_EMPTY (0).
 116  * The cluster must be locked.
 117  */
 118 uint8_t
 119 hammer2_cluster_type(hammer2_cluster_t *cluster)
 120 {
 121         if (cluster->error == 0) {
 122                 KKASSERT(cluster->focus != NULL);
 123                 return(cluster->focus->bref.type);
 124         }
 125         return 0;
 126 }
 127
 128 /*
 129  * Returns non-zero if the cluster's focus is flagged as being modified.
 130  *
 131  * If the cluster is errored, returns 0.
 132  */
 133 static
 134 int
 135 hammer2_cluster_modified(hammer2_cluster_t *cluster)
 136 {
 137         if (cluster->error == 0) {
 138                 KKASSERT(cluster->focus != NULL);
 139                 return((cluster->focus->flags & HAMMER2_CHAIN_MODIFIED) != 0);
 140         }
 141         return 0;
 142 }
 143
 144 /*
 145  * Returns the bref of the cluster's focus, sans any data-offset information
 146  * (since offset information is per-node and wouldn't be useful).
 147  *
 148  * Callers use this function to access modify_tid, mirror_tid, type,
 149  * key, and keybits.
 150  *
 151  * If the cluster is errored, returns an empty bref.
 152  * The cluster must be locked.
 153  */
 154 void
 155 hammer2_cluster_bref(hammer2_cluster_t *cluster, hammer2_blockref_t *bref)
 156 {
 157         if (cluster->error == 0) {
 158                 KKASSERT(cluster->focus != NULL);
 159                 *bref = cluster->focus->bref;
 160                 bref->data_off = 0;
 161         } else {
 162                 bzero(bref, sizeof(*bref));
 163         }
 164 }
 165
 166 /*
 167  * Create a degenerate cluster with one ref from a single locked chain.
 168  * The returned cluster will be focused on the chain and inherit its
 169  * error state.
 170  *
 171  * The chain's lock and reference are transfered to the new cluster, so
 172  * the caller should not try to unlock the chain separately.
 173  *
 174  * We fake the flags.
 175  */
 176 hammer2_cluster_t *
 177 hammer2_cluster_from_chain(hammer2_chain_t *chain)
 178 {
 179         hammer2_cluster_t *cluster;
 180
 181         cluster = kmalloc(sizeof(*cluster), M_HAMMER2, M_WAITOK | M_ZERO);
 182         cluster->array[0].chain = chain;
 183         cluster->array[0].flags = HAMMER2_CITEM_FEMOD;
 184         cluster->nchains = 1;
 185         cluster->focus = chain;
 186         cluster->focus_index = 0;
 187         cluster->pmp = chain->pmp;
 188         cluster->refs = 1;
 189         cluster->error = chain->error;
 190         cluster->flags = HAMMER2_CLUSTER_LOCKED |
 191                          HAMMER2_CLUSTER_WRHARD |
 192                          HAMMER2_CLUSTER_RDHARD |
 193                          HAMMER2_CLUSTER_MSYNCED |
 194                          HAMMER2_CLUSTER_SSYNCED;
 195
 196         return cluster;
 197 }
 198
 199 /*
 200  * Add a reference to a cluster and its underlying chains.
 201  *
 202  * We must also ref the underlying chains in order to allow ref/unlock
 203  * sequences to later re-lock.
 204  */
 205 void
 206 hammer2_cluster_ref(hammer2_cluster_t *cluster)
 207 {
 208         atomic_add_int(&cluster->refs, 1);
 209 }
 210
 211 /*
 212  * Drop the caller's reference to the cluster.  When the ref count drops to
 213  * zero this function frees the cluster and drops all underlying chains.
 214  *
 215  * In-progress read I/Os are typically detached from the cluster once the
 216  * first one returns (the remaining stay attached to the DIOs but are then
 217  * ignored and drop naturally).
 218  */
 219 void
 220 hammer2_cluster_drop(hammer2_cluster_t *cluster)
 221 {
 222         hammer2_chain_t *chain;
 223         int i;
 224
 225         KKASSERT(cluster->refs > 0);
 226         if (atomic_fetchadd_int(&cluster->refs, -1) == 1) {
 227                 cluster->focus = NULL;          /* safety XXX chg to assert */
 228                 cluster->focus_index = 0;
 229
 230                 for (i = 0; i < cluster->nchains; ++i) {
 231                         chain = cluster->array[i].chain;
 232                         if (chain) {
 233                                 hammer2_chain_drop(chain);
 234                                 cluster->array[i].chain = NULL; /* safety */
 235                         }
 236                 }
 237                 cluster->nchains = 0;                           /* safety */
 238
 239                 kfree(cluster, M_HAMMER2);
 240                 /* cluster is invalid */
 241         }
 242 }
 243
 244 /*
 245  * Lock a cluster.  Cluster must already be referenced.  Focus is maintained.
 246  *
 247  * WARNING! This function expects the caller to handle resolution of the
 248  *          cluster.  We never re-resolve the cluster in this function,
 249  *          because it might be used to temporarily unlock/relock a cparent
 250  *          in an iteration or recursrion, and the cparents elements do not
 251  *          necessarily match.
 252  */
 253 void
 254 hammer2_cluster_lock(hammer2_cluster_t *cluster, int how)
 255 {
 256         hammer2_chain_t *chain;
 257         int i;
 258
 259         /* cannot be on inode-embedded cluster template, must be on copy */
 260         KKASSERT(cluster->refs > 0);
 261         KKASSERT((cluster->flags & HAMMER2_CLUSTER_INODE) == 0);
 262         if (cluster->flags & HAMMER2_CLUSTER_LOCKED) {
 263                 panic("hammer2_cluster_lock: cluster %p already locked!\n",
 264                         cluster);
 265         }
 266         atomic_set_int(&cluster->flags, HAMMER2_CLUSTER_LOCKED);
 267
 268         /*
 269          * Lock chains and resolve state.
 270          */
 271         for (i = 0; i < cluster->nchains; ++i) {
 272                 chain = cluster->array[i].chain;
 273                 if (chain == NULL)
 274                         continue;
 275                 hammer2_chain_lock(chain, how);
 276         }
 277 }
 278
 279 /*
 280  * Calculate the clustering state for the cluster and set its focus.
 281  * This routine must be called with care.  For example, it should not
 282  * normally be called after relocking a non-leaf cluster because parent
 283  * clusters help iterations and each element might be at a slightly different
 284  * indirect node (each node's topology is independently indexed).
 285  *
 286  * HAMMER2_CITEM_FEMOD flags which elements can be modified by normal
 287  * operations.  Typically this is only set on a quorum of MASTERs or
 288  * on a SOFT_MASTER.  Also as a degenerate case on SUPROOT.  If a SOFT_MASTER
 289  * is present, this bit is *not* set on a quorum of MASTERs.  The
 290  * synchronization code ignores this bit, but all hammer2_cluster_*() calls
 291  * that create/modify/delete elements use it.
 292  *
 293  * The chains making up the cluster may be narrowed down based on quorum
 294  * acceptability, and if RESOLVE_RDONLY is specified the chains can be
 295  * narrowed down to a single chain as long as the entire subtopology is known
 296  * to be intact.  So, for example, we can narrow a read-only op to a single
 297  * fast SLAVE but if we focus a CACHE chain we must still retain at least
 298  * a SLAVE to ensure that the subtopology can be accessed.
 299  *
 300  * RESOLVE_RDONLY operations are effectively as-of so the quorum does not need
 301  * to be maintained once the topology is validated as-of the top level of
 302  * the operation.
 303  *
 304  * If a failure occurs the operation must be aborted by higher-level code and
 305  * retried. XXX
 306  */
 307 void
 308 hammer2_cluster_resolve(hammer2_cluster_t *cluster)
 309 {
 310         hammer2_chain_t *chain;
 311         hammer2_chain_t *focus;
 312         hammer2_pfs_t *pmp;
 313         hammer2_tid_t quorum_tid;
 314         hammer2_tid_t last_best_quorum_tid;
 315         int focus_pfs_type;
 316         uint32_t nflags;
 317         int ttlmasters;
 318         int ttlslaves;
 319         int nmasters;
 320         int nslaves;
 321         int nquorum;
 322         int smpresent;
 323         int i;
 324
 325         cluster->error = 0;
 326         cluster->focus = NULL;
 327
 328         focus_pfs_type = 0;
 329         nflags = 0;
 330         ttlmasters = 0;
 331         ttlslaves = 0;
 332         nmasters = 0;
 333         nslaves = 0;
 334
 335         /*
 336          * Calculate quorum
 337          */
 338         pmp = cluster->pmp;
 339         KKASSERT(pmp != NULL || cluster->nchains == 0);
 340         nquorum = pmp ? pmp->pfs_nmasters / 2 + 1 : 0;
 341         smpresent = 0;
 342
 343         /*
 344          * Pass 1
 345          *
 346          * NOTE: A NULL chain is not necessarily an error, it could be
 347          *       e.g. a lookup failure or the end of an iteration.
 348          *       Process normally.
 349          */
 350         for (i = 0; i < cluster->nchains; ++i) {
 351                 chain = cluster->array[i].chain;
 352                 if (chain && chain->error) {
 353                         if (cluster->focus == NULL || cluster->focus == chain) {
 354                                 /* error will be overridden by valid focus */
 355                                 cluster->error = chain->error;
 356                         }
 357
 358                         /*
 359                          * Must count total masters and slaves whether the
 360                          * chain is errored or not.
 361                          */
 362                         switch (cluster->pmp->pfs_types[i]) {
 363                         case HAMMER2_PFSTYPE_SUPROOT:
 364                         case HAMMER2_PFSTYPE_MASTER:
 365                                 ++ttlmasters;
 366                                 break;
 367                         case HAMMER2_PFSTYPE_SLAVE:
 368                                 ++ttlslaves;
 369                                 break;
 370                         }
 371                         continue;
 372                 }
 373                 switch (cluster->pmp->pfs_types[i]) {
 374                 case HAMMER2_PFSTYPE_MASTER:
 375                         ++ttlmasters;
 376                         break;
 377                 case HAMMER2_PFSTYPE_SLAVE:
 378                         ++ttlslaves;
 379                         break;
 380                 case HAMMER2_PFSTYPE_SOFT_MASTER:
 381                         nflags |= HAMMER2_CLUSTER_WRSOFT;
 382                         nflags |= HAMMER2_CLUSTER_RDSOFT;
 383                         smpresent = 1;
 384                         break;
 385                 case HAMMER2_PFSTYPE_SOFT_SLAVE:
 386                         nflags |= HAMMER2_CLUSTER_RDSOFT;
 387                         break;
 388                 case HAMMER2_PFSTYPE_SUPROOT:
 389                         /*
 390                          * Degenerate cluster representing the super-root
 391                          * topology on a single device.  Fake stuff so
 392                          * cluster ops work as expected.
 393                          */
 394                         nflags |= HAMMER2_CLUSTER_WRHARD;
 395                         nflags |= HAMMER2_CLUSTER_RDHARD;
 396                         cluster->focus_index = i;
 397                         cluster->focus = chain;
 398                         cluster->error = chain ? chain->error : 0;
 399                         ++ttlmasters;
 400                         break;
 401                 default:
 402                         break;
 403                 }
 404         }
 405
 406         /*
 407          * Pass 2
 408          *
 409          * Resolve masters.  Calculate nmasters for the highest matching
 410          * TID, if a quorum cannot be attained try the next lower matching
 411          * TID until we exhaust TIDs.
 412          *
 413          * NOTE: A NULL chain is not necessarily an error, it could be
 414          *       e.g. a lookup failure or the end of an iteration.
 415          *       Process normally.
 416          */
 417         last_best_quorum_tid = HAMMER2_TID_MAX;
 418         quorum_tid = 0;         /* fix gcc warning */
 419
 420         while (nmasters < nquorum && last_best_quorum_tid != 0) {
 421                 nmasters = 0;
 422                 quorum_tid = 0;
 423
 424                 for (i = 0; i < cluster->nchains; ++i) {
 425                         switch (cluster->pmp->pfs_types[i]) {
 426                         case HAMMER2_PFSTYPE_SUPROOT:
 427                         case HAMMER2_PFSTYPE_MASTER:
 428                                 break;
 429                         default:
 430                                 continue;
 431                         }
 432                         chain = cluster->array[i].chain;
 433
 434                         if (cluster->array[i].flags & HAMMER2_CITEM_INVALID) {
 435                                 /*
 436                                  * Invalid as in unsynchronized, cannot be
 437                                  * used to calculate the quorum.
 438                                  */
 439                         } else if (chain == NULL && quorum_tid == 0) {
 440                                 /*
 441                                  * NULL chain on master matches NULL chains
 442                                  * on other masters.
 443                                  */
 444                                 ++nmasters;
 445                         } else if (quorum_tid < last_best_quorum_tid &&
 446                                    chain != NULL &&
 447                                    (quorum_tid < chain->bref.modify_tid ||
 448                                     nmasters == 0)) {
 449                                 /*
 450                                  * Better TID located, reset nmasters count.
 451                                  */
 452                                 nmasters = 1;
 453                                 quorum_tid = chain->bref.modify_tid;
 454                         } else if (chain &&
 455                                    quorum_tid == chain->bref.modify_tid) {
 456                                 /*
 457                                  * TID matches current collection.
 458                                  */
 459                                 ++nmasters;
 460                         }
 461                 }
 462                 if (nmasters >= nquorum)
 463                         break;
 464                 last_best_quorum_tid = quorum_tid;
 465         }
 466
 467         /*
 468          * Pass 3
 469          *
 470          * NOTE: A NULL chain is not necessarily an error, it could be
 471          *       e.g. a lookup failure or the end of an iteration.
 472          *       Process normally.
 473          */
 474         for (i = 0; i < cluster->nchains; ++i) {
 475                 cluster->array[i].flags &= ~HAMMER2_CITEM_FEMOD;
 476                 chain = cluster->array[i].chain;
 477                 if (chain && chain->error) {
 478                         if (cluster->focus == NULL || cluster->focus == chain) {
 479                                 /* error will be overridden by valid focus */
 480                                 cluster->error = chain->error;
 481                         }
 482                         continue;
 483                 }
 484
 485                 switch (cluster->pmp->pfs_types[i]) {
 486                 case HAMMER2_PFSTYPE_MASTER:
 487                         /*
 488                          * We must have enough up-to-date masters to reach
 489                          * a quorum and the master modify_tid must match
 490                          * the quorum's modify_tid.
 491                          *
 492                          * Do not select an errored or out-of-sync master.
 493                          */
 494                         if (cluster->array[i].flags & HAMMER2_CITEM_INVALID) {
 495                                 nflags |= HAMMER2_CLUSTER_UNHARD;
 496                         } else if (nmasters >= nquorum &&
 497                                    (chain == NULL || chain->error == 0) &&
 498                                    ((chain == NULL && quorum_tid == 0) ||
 499                                     (chain != NULL && quorum_tid ==
 500                                                   chain->bref.modify_tid))) {
 501                                 nflags |= HAMMER2_CLUSTER_WRHARD;
 502                                 nflags |= HAMMER2_CLUSTER_RDHARD;
 503                                 if (!smpresent) {
 504                                         cluster->array[i].flags |=
 505                                                         HAMMER2_CITEM_FEMOD;
 506                                 }
 507                                 if (cluster->focus == NULL ||
 508                                     focus_pfs_type == HAMMER2_PFSTYPE_SLAVE) {
 509                                         focus_pfs_type = HAMMER2_PFSTYPE_MASTER;
 510                                         cluster->focus_index = i;
 511                                         cluster->focus = chain; /* NULL ok */
 512                                         cluster->error = chain ? chain->error :
 513                                                                  0;
 514                                 }
 515                         } else if (chain == NULL || chain->error == 0) {
 516                                 nflags |= HAMMER2_CLUSTER_UNHARD;
 517                         }
 518                         break;
 519                 case HAMMER2_PFSTYPE_SLAVE:
 520                         /*
 521                          * We must have enough up-to-date masters to reach
 522                          * a quorum and the slave modify_tid must match the
 523                          * quorum's modify_tid.
 524                          *
 525                          * Do not select an errored slave.
 526                          */
 527                         if (cluster->array[i].flags & HAMMER2_CITEM_INVALID) {
 528                                 nflags |= HAMMER2_CLUSTER_UNHARD;
 529                         } else if (nmasters >= nquorum &&
 530                                    (chain == NULL || chain->error == 0) &&
 531                                    ((chain == NULL && quorum_tid == 0) ||
 532                                     (chain && quorum_tid ==
 533                                               chain->bref.modify_tid))) {
 534                                 ++nslaves;
 535                                 nflags |= HAMMER2_CLUSTER_RDHARD;
 536 #if 0
 537                                 /* XXX optimize for RESOLVE_RDONLY */
 538                                 if (cluster->focus == NULL) {
 539                                         focus_pfs_type = HAMMER2_PFSTYPE_SLAVE;
 540                                         cluster->focus_index = i;
 541                                         cluster->focus = chain; /* NULL ok */
 542                                         cluster->error = chain ? chain->error :
 543                                                                  0;
 544                                 }
 545 #endif
 546                         } else if (chain == NULL || chain->error == 0) {
 547                                 nflags |= HAMMER2_CLUSTER_UNSOFT;
 548                         }
 549                         break;
 550                 case HAMMER2_PFSTYPE_SOFT_MASTER:
 551                         /*
 552                          * Directly mounted soft master always wins.  There
 553                          * should be only one.
 554                          */
 555                         KKASSERT(focus_pfs_type != HAMMER2_PFSTYPE_SOFT_MASTER);
 556                         cluster->focus_index = i;
 557                         cluster->focus = chain;
 558                         cluster->error = chain ? chain->error : 0;
 559                         focus_pfs_type = HAMMER2_PFSTYPE_SOFT_MASTER;
 560                         cluster->array[i].flags |= HAMMER2_CITEM_FEMOD;
 561                         break;
 562                 case HAMMER2_PFSTYPE_SOFT_SLAVE:
 563                         /*
 564                          * Directly mounted soft slave always wins.  There
 565                          * should be only one.
 566                          */
 567                         KKASSERT(focus_pfs_type != HAMMER2_PFSTYPE_SOFT_SLAVE);
 568                         if (focus_pfs_type != HAMMER2_PFSTYPE_SOFT_MASTER) {
 569                                 cluster->focus_index = i;
 570                                 cluster->focus = chain;
 571                                 cluster->error = chain ? chain->error : 0;
 572                                 focus_pfs_type = HAMMER2_PFSTYPE_SOFT_SLAVE;
 573                         }
 574                         break;
 575                 case HAMMER2_PFSTYPE_SUPROOT:
 576                         /*
 577                          * spmp (degenerate case)
 578                          */
 579                         KKASSERT(i == 0);
 580                         cluster->focus_index = i;
 581                         cluster->focus = chain;
 582                         cluster->error = chain ? chain->error : 0;
 583                         focus_pfs_type = HAMMER2_PFSTYPE_SUPROOT;
 584                         cluster->array[i].flags |= HAMMER2_CITEM_FEMOD;
 585                         break;
 586                 default:
 587                         break;
 588                 }
 589         }
 590
 591         /*
 592          * Focus now set, adjust ddflag.  Skip this pass if the focus
 593          * is bad or if we are at the PFS root (the bref won't match at
 594          * the PFS root, obviously).
 595          */
 596         focus = cluster->focus;
 597         if (focus) {
 598                 cluster->ddflag =
 599                         (cluster->focus->bref.type == HAMMER2_BREF_TYPE_INODE);
 600         } else {
 601                 cluster->ddflag = 0;
 602                 goto skip4;
 603         }
 604         if (cluster->focus->flags & HAMMER2_CHAIN_PFSBOUNDARY)
 605                 goto skip4;
 606
 607         /*
 608          * Pass 4
 609          *
 610          * Validate the elements that were not marked invalid.  They should
 611          * match.
 612          */
 613         for (i = 0; i < cluster->nchains; ++i) {
 614                 int ddflag;
 615
 616                 chain = cluster->array[i].chain;
 617
 618                 if (chain == NULL)
 619                         continue;
 620                 if (chain == focus)
 621                         continue;
 622                 if (cluster->array[i].flags & HAMMER2_CITEM_INVALID)
 623                         continue;
 624
 625                 ddflag = (chain->bref.type == HAMMER2_BREF_TYPE_INODE);
 626                 if (chain->bref.type != focus->bref.type ||
 627                     chain->bref.key != focus->bref.key ||
 628                     chain->bref.keybits != focus->bref.keybits ||
 629                     chain->bref.modify_tid != focus->bref.modify_tid ||
 630                     chain->bytes != focus->bytes ||
 631                     ddflag != cluster->ddflag) {
 632                         cluster->array[i].flags |= HAMMER2_CITEM_INVALID;
 633                         if (hammer2_debug & 1)
 634                         kprintf("cluster_resolve: matching modify_tid failed "
 635                                 "bref test: idx=%d type=%02x/%02x "
 636                                 "key=%016jx/%d-%016jx/%d "
 637                                 "mod=%016jx/%016jx bytes=%u/%u\n",
 638                                 i,
 639                                 chain->bref.type, focus->bref.type,
 640                                 chain->bref.key, chain->bref.keybits,
 641                                 focus->bref.key, focus->bref.keybits,
 642                                 chain->bref.modify_tid, focus->bref.modify_tid,
 643                                 chain->bytes, focus->bytes);
 644                         if (hammer2_debug & 0x4000)
 645                                 panic("cluster_resolve");
 646                         /* flag issue and force resync? */
 647                 }
 648         }
 649 skip4:
 650
 651         if (ttlslaves == 0)
 652                 nflags |= HAMMER2_CLUSTER_NOSOFT;
 653         if (ttlmasters == 0)
 654                 nflags |= HAMMER2_CLUSTER_NOHARD;
 655
 656         /*
 657          * Set SSYNCED or MSYNCED for slaves and masters respectively if
 658          * all available nodes (even if 0 are available) are fully
 659          * synchronized.  This is used by the synchronization thread to
 660          * determine if there is work it could potentially accomplish.
 661          */
 662         if (nslaves == ttlslaves)
 663                 nflags |= HAMMER2_CLUSTER_SSYNCED;
 664         if (nmasters == ttlmasters)
 665                 nflags |= HAMMER2_CLUSTER_MSYNCED;
 666
 667         /*
 668          * Determine if the cluster was successfully locked for the
 669          * requested operation and generate an error code.  The cluster
 670          * will not be locked (or ref'd) if an error is returned.
 671          */
 672         atomic_set_int(&cluster->flags, nflags);
 673         atomic_clear_int(&cluster->flags, HAMMER2_CLUSTER_ZFLAGS & ~nflags);
 674 }
 675
 676 /*
 677  * This is used by the XOPS subsystem to calculate the state of
 678  * the collection and tell hammer2_xop_collect() what to do with it.
 679  * The collection can be in various states of desynchronization, the
 680  * caller specifically wants to resolve the passed-in key.
 681  *
 682  * Return values:
 683  *      0               - Quorum agreement, key is valid
 684  *
 685  *      ENOENT          - Quorum agreement, end of scan
 686  *
 687  *      ESRCH           - Quorum agreement, key is INVALID (caller should
 688  *                        skip key).
 689  *
 690  *      EIO             - Quorum agreement but all elements had errors.
 691  *
 692  *      EDEADLK         - No quorum agreement possible for key, a repair
 693  *                        may be needed.  Caller has to decide what to do,
 694  *                        possibly iterating the key or generating an EIO.
 695  *
 696  *      EINPROGRESS     - No quorum agreement yet, but agreement is still
 697  *                        possible if caller waits for more responses.  Caller
 698  *                        should not iterate key.
 699  *
 700  * NOTE! If the pmp is in HMNT2_LOCAL mode, the cluster check always succeeds.
 701  *
 702  * XXX needs to handle SOFT_MASTER and SOFT_SLAVE
 703  */
 704 int
 705 hammer2_cluster_check(hammer2_cluster_t *cluster, hammer2_key_t key, int flags)
 706 {
 707         hammer2_chain_t *chain;
 708         hammer2_chain_t *focus;
 709         hammer2_pfs_t *pmp;
 710         hammer2_tid_t quorum_tid;
 711         hammer2_tid_t last_best_quorum_tid;
 712         uint32_t nflags;
 713         int ttlmasters;
 714         int ttlslaves;
 715         int nmasters;
 716         int nmasters_keymatch;
 717         int nslaves;
 718         int nquorum;
 719         int umasters;   /* unknown masters (still in progress) */
 720         int smpresent;
 721         int error;
 722         int i;
 723
 724         cluster->error = 0;
 725         cluster->focus = NULL;
 726
 727         pmp = cluster->pmp;
 728         KKASSERT(pmp != NULL || cluster->nchains == 0);
 729
 730         /*
 731          * Calculate quorum
 732          */
 733         nquorum = pmp ? pmp->pfs_nmasters / 2 + 1 : 0;
 734         smpresent = 0;
 735         nflags = 0;
 736         ttlmasters = 0;
 737         ttlslaves = 0;
 738
 739         /*
 740          * Pass 1
 741          *
 742          * NOTE: A NULL chain is not necessarily an error, it could be
 743          *       e.g. a lookup failure or the end of an iteration.
 744          *       Process normally.
 745          */
 746         for (i = 0; i < cluster->nchains; ++i) {
 747                 cluster->array[i].flags &= ~HAMMER2_CITEM_FEMOD;
 748                 cluster->array[i].flags |= HAMMER2_CITEM_INVALID;
 749
 750                 chain = cluster->array[i].chain;
 751                 error = cluster->array[i].error;
 752                 if (chain && error) {
 753                         if (cluster->focus == NULL || cluster->focus == chain) {
 754                                 /* error will be overridden by valid focus */
 755                                 /* XXX */
 756                         }
 757
 758                         /*
 759                          * Must count total masters and slaves whether the
 760                          * chain is errored or not.
 761                          */
 762                         switch (cluster->pmp->pfs_types[i]) {
 763                         case HAMMER2_PFSTYPE_SUPROOT:
 764                         case HAMMER2_PFSTYPE_MASTER:
 765                                 ++ttlmasters;
 766                                 break;
 767                         case HAMMER2_PFSTYPE_SLAVE:
 768                                 ++ttlslaves;
 769                                 break;
 770                         }
 771                         continue;
 772                 }
 773                 switch (cluster->pmp->pfs_types[i]) {
 774                 case HAMMER2_PFSTYPE_MASTER:
 775                         ++ttlmasters;
 776                         break;
 777                 case HAMMER2_PFSTYPE_SLAVE:
 778                         ++ttlslaves;
 779                         break;
 780                 case HAMMER2_PFSTYPE_SOFT_MASTER:
 781                         nflags |= HAMMER2_CLUSTER_WRSOFT;
 782                         nflags |= HAMMER2_CLUSTER_RDSOFT;
 783                         smpresent = 1;
 784                         break;
 785                 case HAMMER2_PFSTYPE_SOFT_SLAVE:
 786                         nflags |= HAMMER2_CLUSTER_RDSOFT;
 787                         break;
 788                 case HAMMER2_PFSTYPE_SUPROOT:
 789                         /*
 790                          * Degenerate cluster representing the super-root
 791                          * topology on a single device.  Fake stuff so
 792                          * cluster ops work as expected.
 793                          */
 794                         ++ttlmasters;
 795                         nflags |= HAMMER2_CLUSTER_WRHARD;
 796                         nflags |= HAMMER2_CLUSTER_RDHARD;
 797                         cluster->focus_index = i;
 798                         cluster->focus = chain;
 799                         cluster->error = error;
 800                         break;
 801                 default:
 802                         break;
 803                 }
 804         }
 805
 806         /*
 807          * Pass 2
 808          *
 809          * Resolve nmasters             - master nodes fully match
 810          *
 811          * Resolve umasters             - master nodes operation still
 812          *                                in progress
 813          *
 814          * Resolve nmasters_keymatch    - master nodes match the passed-in
 815          *                                key and may or may not match
 816          *                                the quorum-agreed tid.
 817          *
 818          * The quorum-agreed TID is the highest matching TID.
 819          */
 820         last_best_quorum_tid = HAMMER2_TID_MAX;
 821         umasters = 0;
 822         nmasters = 0;
 823         nmasters_keymatch = 0;
 824         quorum_tid = 0;         /* fix gcc warning */
 825
 826         while (nmasters < nquorum && last_best_quorum_tid != 0) {
 827                 umasters = 0;
 828                 nmasters = 0;
 829                 nmasters_keymatch = 0;
 830                 quorum_tid = 0;
 831
 832                 for (i = 0; i < cluster->nchains; ++i) {
 833                         /* XXX SOFT smpresent handling */
 834                         switch(cluster->pmp->pfs_types[i]) {
 835                         case HAMMER2_PFSTYPE_MASTER:
 836                         case HAMMER2_PFSTYPE_SUPROOT:
 837                                 break;
 838                         default:
 839                                 continue;
 840                         }
 841
 842                         chain = cluster->array[i].chain;
 843                         error = cluster->array[i].error;
 844
 845                         /*
 846                          * Skip elements still in progress.  umasters keeps
 847                          * track of masters that might still be in-progress.
 848                          */
 849                         if (chain == NULL && (cluster->array[i].flags &
 850                                               HAMMER2_CITEM_NULL) == 0) {
 851                                 ++umasters;
 852                                 continue;
 853                         }
 854
 855                         /*
 856                          * Key match?
 857                          */
 858                         if (flags & HAMMER2_CHECK_NULL) {
 859                                 if (chain == NULL) {
 860                                         ++nmasters;
 861                                         ++nmasters_keymatch;
 862                                         if (cluster->error == 0)
 863                                                 cluster->error = error;
 864                                 }
 865                         } else if (chain &&
 866                                    (key == (hammer2_key_t)-1 ||
 867                                     chain->bref.key == key)) {
 868                                 ++nmasters_keymatch;
 869
 870                                 if (chain->bref.modify_tid <
 871                                      last_best_quorum_tid &&
 872                                     quorum_tid < chain->bref.modify_tid) {
 873                                         /*
 874                                          * Select new TID as master if better
 875                                          * than any found so far in this loop,
 876                                          * as long as it does not reach the
 877                                          * best tid found in the previous loop.
 878                                          */
 879                                         nmasters = 0;
 880                                         quorum_tid = chain->bref.modify_tid;
 881                                 }
 882                                 if (quorum_tid == chain->bref.modify_tid) {
 883                                         /*
 884                                          * TID matches current collection.
 885                                          *
 886                                          * (error handled in next pass)
 887                                          */
 888                                         ++nmasters;
 889                                         if (chain->error == 0) {
 890                                                 cluster->focus = chain;
 891                                                 cluster->focus_index = i;
 892                                         }
 893                                 }
 894                         }
 895                 }
 896                 if (nmasters >= nquorum)
 897                         break;
 898                 last_best_quorum_tid = quorum_tid;
 899         }
 900
 901         /*
 902         kprintf("nmasters %d/%d nmaster_keymatch=%d umasters=%d\n",
 903                 nmasters, nquorum, nmasters_keymatch, umasters);
 904         */
 905
 906         /*
 907          * Early return if we do not have enough masters.
 908          */
 909         if (nmasters < nquorum) {
 910                 if (nmasters + umasters >= nquorum)
 911                         return EINPROGRESS;
 912                 if (nmasters_keymatch < nquorum)
 913                         return ESRCH;
 914                 return EDEADLK;
 915         }
 916
 917         /*
 918          * Validated end of scan.
 919          */
 920         if (flags & HAMMER2_CHECK_NULL) {
 921                 if (cluster->error == 0)
 922                         cluster->error = ENOENT;
 923                 return cluster->error;
 924         }
 925
 926         /*
 927          * If we have a NULL focus at this point the agreeing quorum all
 928          * had chain errors.
 929          */
 930         if (cluster->focus == NULL)
 931                 return EIO;
 932
 933         /*
 934          * Pass 3
 935          *
 936          * We have quorum agreement, validate elements, not end of scan.
 937          */
 938         nslaves = 0;
 939         cluster->error = 0;
 940
 941         for (i = 0; i < cluster->nchains; ++i) {
 942                 chain = cluster->array[i].chain;
 943                 error = cluster->array[i].error;
 944                 if (chain == NULL ||
 945                     chain->bref.key != key ||
 946                     chain->bref.modify_tid != quorum_tid) {
 947                         continue;
 948                 }
 949
 950                 /*
 951                  * Quorum Match
 952                  *
 953                  * XXX for now, cumulative error.
 954                  */
 955                 if (cluster->error == 0)
 956                         cluster->error = error;
 957
 958                 switch (cluster->pmp->pfs_types[i]) {
 959                 case HAMMER2_PFSTYPE_MASTER:
 960                         cluster->array[i].flags |= HAMMER2_CITEM_FEMOD;
 961                         cluster->array[i].flags &= ~HAMMER2_CITEM_INVALID;
 962                         nflags |= HAMMER2_CLUSTER_WRHARD;
 963                         nflags |= HAMMER2_CLUSTER_RDHARD;
 964                         break;
 965                 case HAMMER2_PFSTYPE_SLAVE:
 966                         /*
 967                          * We must have enough up-to-date masters to reach
 968                          * a quorum and the slave modify_tid must match the
 969                          * quorum's modify_tid.
 970                          *
 971                          * Do not select an errored slave.
 972                          */
 973                         cluster->array[i].flags &= ~HAMMER2_CITEM_INVALID;
 974                         nflags |= HAMMER2_CLUSTER_RDHARD;
 975                         ++nslaves;
 976                         break;
 977                 case HAMMER2_PFSTYPE_SOFT_MASTER:
 978                         /*
 979                          * Directly mounted soft master always wins.  There
 980                          * should be only one.
 981                          */
 982                         cluster->array[i].flags |= HAMMER2_CITEM_FEMOD;
 983                         cluster->array[i].flags &= ~HAMMER2_CITEM_INVALID;
 984                         break;
 985                 case HAMMER2_PFSTYPE_SOFT_SLAVE:
 986                         /*
 987                          * Directly mounted soft slave always wins.  There
 988                          * should be only one.
 989                          *
 990                          * XXX
 991                          */
 992                         cluster->array[i].flags &= ~HAMMER2_CITEM_INVALID;
 993                         break;
 994                 case HAMMER2_PFSTYPE_SUPROOT:
 995                         /*
 996                          * spmp (degenerate case)
 997                          */
 998                         cluster->array[i].flags |= HAMMER2_CITEM_FEMOD;
 999                         cluster->array[i].flags &= ~HAMMER2_CITEM_INVALID;
1000                         nflags |= HAMMER2_CLUSTER_WRHARD;
1001                         nflags |= HAMMER2_CLUSTER_RDHARD;
1002                         break;
1003                 default:
1004                         break;
1005                 }
1006         }
1007
1008         /*
1009          * Focus now set, adjust ddflag.  Skip this pass if the focus
1010          * is bad or if we are at the PFS root (the bref won't match at
1011          * the PFS root, obviously).
1012          */
1013         focus = cluster->focus;
1014         if (focus) {
1015                 cluster->ddflag =
1016                         (cluster->focus->bref.type == HAMMER2_BREF_TYPE_INODE);
1017         } else {
1018                 cluster->ddflag = 0;
1019                 goto skip4;
1020         }
1021         if (cluster->focus->flags & HAMMER2_CHAIN_PFSBOUNDARY)
1022                 goto skip4;
1023
1024         /*
1025          * Pass 4
1026          *
1027          * Validate the elements that were not marked invalid.  They should
1028          * match.
1029          */
1030         for (i = 0; i < cluster->nchains; ++i) {
1031                 int ddflag;
1032
1033                 chain = cluster->array[i].chain;
1034
1035                 if (chain == NULL)
1036                         continue;
1037                 if (chain == focus)
1038                         continue;
1039                 if (cluster->array[i].flags & HAMMER2_CITEM_INVALID)
1040                         continue;
1041
1042                 ddflag = (chain->bref.type == HAMMER2_BREF_TYPE_INODE);
1043                 if (chain->bref.type != focus->bref.type ||
1044                     chain->bref.key != focus->bref.key ||
1045                     chain->bref.keybits != focus->bref.keybits ||
1046                     chain->bref.modify_tid != focus->bref.modify_tid ||
1047                     chain->bytes != focus->bytes ||
1048                     ddflag != cluster->ddflag) {
1049                         cluster->array[i].flags |= HAMMER2_CITEM_INVALID;
1050                         if (hammer2_debug & 1)
1051                         kprintf("cluster_resolve: matching modify_tid failed "
1052                                 "bref test: idx=%d type=%02x/%02x "
1053                                 "key=%016jx/%d-%016jx/%d "
1054                                 "mod=%016jx/%016jx bytes=%u/%u\n",
1055                                 i,
1056                                 chain->bref.type, focus->bref.type,
1057                                 chain->bref.key, chain->bref.keybits,
1058                                 focus->bref.key, focus->bref.keybits,
1059                                 chain->bref.modify_tid, focus->bref.modify_tid,
1060                                 chain->bytes, focus->bytes);
1061                         if (hammer2_debug & 0x4000)
1062                                 panic("cluster_resolve");
1063                         /* flag issue and force resync? */
1064                 }
1065         }
1066 skip4:
1067
1068         if (ttlslaves == 0)
1069                 nflags |= HAMMER2_CLUSTER_NOSOFT;
1070         if (ttlmasters == 0)
1071                 nflags |= HAMMER2_CLUSTER_NOHARD;
1072
1073         /*
1074          * Set SSYNCED or MSYNCED for slaves and masters respectively if
1075          * all available nodes (even if 0 are available) are fully
1076          * synchronized.  This is used by the synchronization thread to
1077          * determine if there is work it could potentially accomplish.
1078          */
1079         if (nslaves == ttlslaves)
1080                 nflags |= HAMMER2_CLUSTER_SSYNCED;
1081         if (nmasters == ttlmasters)
1082                 nflags |= HAMMER2_CLUSTER_MSYNCED;
1083
1084         /*
1085          * Determine if the cluster was successfully locked for the
1086          * requested operation and generate an error code.  The cluster
1087          * will not be locked (or ref'd) if an error is returned.
1088          */
1089         atomic_set_int(&cluster->flags, nflags);
1090         atomic_clear_int(&cluster->flags, HAMMER2_CLUSTER_ZFLAGS & ~nflags);
1091
1092         return cluster->error;
1093 }
1094
1095 /*
1096  * This is used by the sync thread to force non-NULL elements of a copy
1097  * of the pmp->iroot cluster to be good which is required to prime the
1098  * sync.
1099  */
1100 void
1101 hammer2_cluster_forcegood(hammer2_cluster_t *cluster)
1102 {
1103         int i;
1104
1105         for (i = 0; i < cluster->nchains; ++i) {
1106                 if (cluster->array[i].chain)
1107                         cluster->array[i].flags &= ~HAMMER2_CITEM_INVALID;
1108         }
1109 }
1110
1111 /*
1112  * Unlock a cluster.  Refcount and focus is maintained.
1113  */
1114 void
1115 hammer2_cluster_unlock(hammer2_cluster_t *cluster)
1116 {
1117         hammer2_chain_t *chain;
1118         int i;
1119
1120         if ((cluster->flags & HAMMER2_CLUSTER_LOCKED) == 0) {
1121                 kprintf("hammer2_cluster_unlock: cluster %p not locked\n",
1122                         cluster);
1123         }
1124         KKASSERT(cluster->flags & HAMMER2_CLUSTER_LOCKED);
1125         KKASSERT(cluster->refs > 0);
1126         atomic_clear_int(&cluster->flags, HAMMER2_CLUSTER_LOCKED);
1127
1128         for (i = 0; i < cluster->nchains; ++i) {
1129                 chain = cluster->array[i].chain;
1130                 if (chain)
1131                         hammer2_chain_unlock(chain);
1132         }
1133 }
1134
1135 /************************************************************************
1136  *                              CLUSTER I/O                             *
1137  ************************************************************************
1138  *
1139  *
1140  * WARNING! blockref[] array data is not universal.  These functions should
1141  *          only be used to access universal data.
1142  *
1143  * NOTE!    The rdata call will wait for at least one of the chain I/Os to
1144  *          complete if necessary.  The I/O's should have already been
1145  *          initiated by the cluster_lock/chain_lock operation.
1146  *
1147  *          The cluster must already be in a modified state before wdata
1148  *          is called.  The data will already be available for this case.
1149  */
1150 const hammer2_media_data_t *
1151 hammer2_cluster_rdata(hammer2_cluster_t *cluster)
1152 {
1153         KKASSERT(cluster->focus != NULL);
1154         return(cluster->focus->data);
1155 }
1156
1157 hammer2_media_data_t *
1158 hammer2_cluster_wdata(hammer2_cluster_t *cluster)
1159 {
1160         KKASSERT(cluster->focus != NULL);
1161         KKASSERT(hammer2_cluster_modified(cluster));
1162         return(cluster->focus->data);
1163 }