sys/vfs/hammer2/hammer2_flush.c

   1 /*
   2  * Copyright (c) 2011-2015 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  * by Venkatesh Srinivas <vsrinivas@dragonflybsd.org>
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  *
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in
  16  *    the documentation and/or other materials provided with the
  17  *    distribution.
  18  * 3. Neither the name of The DragonFly Project nor the names of its
  19  *    contributors may be used to endorse or promote products derived
  20  *    from this software without specific, prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  23  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  24  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  25  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  26  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  27  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  28  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  29  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  30  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  31  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  32  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  */
  35 /*
  36  *                      TRANSACTION AND FLUSH HANDLING
  37  *
  38  * Deceptively simple but actually fairly difficult to implement properly is
  39  * how I would describe it.
  40  *
  41  * Flushing generally occurs bottom-up but requires a top-down scan to
  42  * locate chains with MODIFIED and/or UPDATE bits set.  The ONFLUSH flag
  43  * tells how to recurse downward to find these chains.
  44  */
  45
  46 #include <sys/cdefs.h>
  47 #include <sys/param.h>
  48 #include <sys/systm.h>
  49 #include <sys/types.h>
  50 #include <sys/lock.h>
  51 #include <sys/uuid.h>
  52
  53 #include "hammer2.h"
  54
  55 #define FLUSH_DEBUG 0
  56
  57 #define HAMMER2_FLUSH_DEPTH_LIMIT       10      /* stack recursion limit */
  58
  59
  60 /*
  61  * Recursively flush the specified chain.  The chain is locked and
  62  * referenced by the caller and will remain so on return.  The chain
  63  * will remain referenced throughout but can temporarily lose its
  64  * lock during the recursion to avoid unnecessarily stalling user
  65  * processes.
  66  */
  67 struct hammer2_flush_info {
  68         hammer2_chain_t *parent;
  69         int             depth;
  70         int             diddeferral;
  71         int             cache_index;
  72         int             flags;
  73         struct h2_flush_list flushq;
  74         hammer2_chain_t *debug;
  75 };
  76
  77 typedef struct hammer2_flush_info hammer2_flush_info_t;
  78
  79 static void hammer2_flush_core(hammer2_flush_info_t *info,
  80                                 hammer2_chain_t *chain, int flags);
  81 static int hammer2_flush_recurse(hammer2_chain_t *child, void *data);
  82
  83 /*
  84  * Any per-pfs transaction initialization goes here.
  85  */
  86 void
  87 hammer2_trans_manage_init(hammer2_pfs_t *pmp)
  88 {
  89 }
  90
  91 /*
  92  * Transaction support for any modifying operation.  Transactions are used
  93  * in the pmp layer by the frontend and in the spmp layer by the backend.
  94  *
  95  * 0                    - Normal transaction, interlocked against flush
  96  *                        transaction.
  97  *
  98  * TRANS_ISFLUSH        - Flush transaction, interlocked against normal
  99  *                        transaction.
 100  *
 101  * TRANS_BUFCACHE       - Buffer cache transaction, no interlock.
 102  *
 103  * Initializing a new transaction allocates a transaction ID.  Typically
 104  * passed a pmp (hmp passed as NULL), indicating a cluster transaction.  Can
 105  * be passed a NULL pmp and non-NULL hmp to indicate a transaction on a single
 106  * media target.  The latter mode is used by the recovery code.
 107  *
 108  * TWO TRANSACTION IDs can run concurrently, where one is a flush and the
 109  * other is a set of any number of concurrent filesystem operations.  We
 110  * can either have <running_fs_ops> + <waiting_flush> + <blocked_fs_ops>
 111  * or we can have <running_flush> + <concurrent_fs_ops>.
 112  *
 113  * During a flush, new fs_ops are only blocked until the fs_ops prior to
 114  * the flush complete.  The new fs_ops can then run concurrent with the flush.
 115  *
 116  * Buffer-cache transactions operate as fs_ops but never block.  A
 117  * buffer-cache flush will run either before or after the current pending
 118  * flush depending on its state.
 119  */
 120 void
 121 hammer2_trans_init(hammer2_pfs_t *pmp, uint32_t flags)
 122 {
 123         uint32_t oflags;
 124         uint32_t nflags;
 125         int dowait;
 126
 127         for (;;) {
 128                 oflags = pmp->trans.flags;
 129                 cpu_ccfence();
 130                 dowait = 0;
 131
 132                 if (flags & HAMMER2_TRANS_ISFLUSH) {
 133                         /*
 134                          * Requesting flush transaction.  Wait for all
 135                          * currently running transactions to finish.
 136                          */
 137                         if (oflags & HAMMER2_TRANS_MASK) {
 138                                 nflags = oflags | HAMMER2_TRANS_FPENDING |
 139                                                   HAMMER2_TRANS_WAITING;
 140                                 dowait = 1;
 141                         } else {
 142                                 nflags = (oflags | flags) + 1;
 143                         }
 144                 } else if (flags & HAMMER2_TRANS_BUFCACHE) {
 145                         /*
 146                          * Requesting strategy transaction.  Generally
 147                          * allowed in all situations unless a flush
 148                          * is running without the preflush flag.
 149                          */
 150                         if ((oflags & (HAMMER2_TRANS_ISFLUSH |
 151                                        HAMMER2_TRANS_PREFLUSH)) ==
 152                             HAMMER2_TRANS_ISFLUSH) {
 153                                 nflags = oflags | HAMMER2_TRANS_WAITING;
 154                                 dowait = 1;
 155                         } else {
 156                                 nflags = (oflags | flags) + 1;
 157                         }
 158                 } else {
 159                         /*
 160                          * Requesting normal transaction.  Wait for any
 161                          * flush to finish before allowing.
 162                          */
 163                         if (oflags & HAMMER2_TRANS_ISFLUSH) {
 164                                 nflags = oflags | HAMMER2_TRANS_WAITING;
 165                                 dowait = 1;
 166                         } else {
 167                                 nflags = (oflags | flags) + 1;
 168                         }
 169                 }
 170                 if (dowait)
 171                         tsleep_interlock(&pmp->trans.sync_wait, 0);
 172                 if (atomic_cmpset_int(&pmp->trans.flags, oflags, nflags)) {
 173                         if (dowait == 0)
 174                                 break;
 175                         tsleep(&pmp->trans.sync_wait, PINTERLOCKED,
 176                                "h2trans", hz);
 177                 } else {
 178                         cpu_pause();
 179                 }
 180                 /* retry */
 181         }
 182 }
 183
 184 /*
 185  * Start a sub-transaction, there is no 'subdone' function.  This will
 186  * issue a new modify_tid (mtid) for the current transaction, which is a
 187  * CLC (cluster level change) id and not a per-node id.
 188  *
 189  * This function must be called for each XOP when multiple XOPs are run in
 190  * sequence within a transaction.
 191  *
 192  * Callers typically update the inode with the transaction mtid manually
 193  * to enforce sequencing.
 194  */
 195 hammer2_tid_t
 196 hammer2_trans_sub(hammer2_pfs_t *pmp)
 197 {
 198         hammer2_tid_t mtid;
 199
 200         mtid = atomic_fetchadd_64(&pmp->modify_tid, 1);
 201
 202         return (mtid);
 203 }
 204
 205 /*
 206  * Clears the PREFLUSH stage, called during a flush transaction after all
 207  * logical buffer I/O has completed.
 208  */
 209 void
 210 hammer2_trans_clear_preflush(hammer2_pfs_t *pmp)
 211 {
 212         atomic_clear_int(&pmp->trans.flags, HAMMER2_TRANS_PREFLUSH);
 213 }
 214
 215 void
 216 hammer2_trans_done(hammer2_pfs_t *pmp)
 217 {
 218         uint32_t oflags;
 219         uint32_t nflags;
 220
 221         for (;;) {
 222                 oflags = pmp->trans.flags;
 223                 cpu_ccfence();
 224                 KKASSERT(oflags & HAMMER2_TRANS_MASK);
 225                 if ((oflags & HAMMER2_TRANS_MASK) == 1) {
 226                         /*
 227                          * This was the last transaction
 228                          */
 229                         nflags = (oflags - 1) & ~(HAMMER2_TRANS_ISFLUSH |
 230                                                   HAMMER2_TRANS_BUFCACHE |
 231                                                   HAMMER2_TRANS_PREFLUSH |
 232                                                   HAMMER2_TRANS_FPENDING |
 233                                                   HAMMER2_TRANS_WAITING);
 234                 } else {
 235                         /*
 236                          * Still transactions pending
 237                          */
 238                         nflags = oflags - 1;
 239                 }
 240                 if (atomic_cmpset_int(&pmp->trans.flags, oflags, nflags)) {
 241                         if ((nflags & HAMMER2_TRANS_MASK) == 0 &&
 242                             (oflags & HAMMER2_TRANS_WAITING)) {
 243                                 wakeup(&pmp->trans.sync_wait);
 244                         }
 245                         break;
 246                 } else {
 247                         cpu_pause();
 248                 }
 249                 /* retry */
 250         }
 251 }
 252
 253 /*
 254  * Obtain new, unique inode number (not serialized by caller).
 255  */
 256 hammer2_tid_t
 257 hammer2_trans_newinum(hammer2_pfs_t *pmp)
 258 {
 259         hammer2_tid_t tid;
 260
 261         tid = atomic_fetchadd_64(&pmp->inode_tid, 1);
 262
 263         return tid;
 264 }
 265
 266 /*
 267  * Assert that a strategy call is ok here.  Strategy calls are legal
 268  *
 269  * (1) In a normal transaction.
 270  * (2) In a flush transaction only if PREFLUSH is also set.
 271  */
 272 void
 273 hammer2_trans_assert_strategy(hammer2_pfs_t *pmp)
 274 {
 275         KKASSERT((pmp->trans.flags & HAMMER2_TRANS_ISFLUSH) == 0 ||
 276                  (pmp->trans.flags & HAMMER2_TRANS_PREFLUSH));
 277 }
 278
 279
 280 /*
 281  * Chains undergoing destruction are removed from the in-memory topology.
 282  * To avoid getting lost these chains are placed on the delayed flush
 283  * queue which will properly dispose of them.
 284  *
 285  * We do this instead of issuing an immediate flush in order to give
 286  * recursive deletions (rm -rf, etc) a chance to remove more of the
 287  * hierarchy, potentially allowing an enormous amount of write I/O to
 288  * be avoided.
 289  */
 290 void
 291 hammer2_delayed_flush(hammer2_chain_t *chain)
 292 {
 293         if ((chain->flags & HAMMER2_CHAIN_DELAYED) == 0) {
 294                 hammer2_spin_ex(&chain->hmp->list_spin);
 295                 if ((chain->flags & (HAMMER2_CHAIN_DELAYED |
 296                                      HAMMER2_CHAIN_DEFERRED)) == 0) {
 297                         atomic_set_int(&chain->flags, HAMMER2_CHAIN_DELAYED |
 298                                                       HAMMER2_CHAIN_DEFERRED);
 299                         TAILQ_INSERT_TAIL(&chain->hmp->flushq,
 300                                           chain, flush_node);
 301                         hammer2_chain_ref(chain);
 302                 }
 303                 hammer2_spin_unex(&chain->hmp->list_spin);
 304         }
 305 }
 306
 307 /*
 308  * Flush the chain and all modified sub-chains through the specified
 309  * synchronization point, propagating blockref updates back up.  As
 310  * part of this propagation, mirror_tid and inode/data usage statistics
 311  * propagates back upward.
 312  *
 313  * modify_tid (clc - cluster level change) is not propagated.
 314  *
 315  * update_tid (clc) is used for validation and is not propagated by this
 316  * function.
 317  *
 318  * This routine can be called from several places but the most important
 319  * is from VFS_SYNC (frontend) via hammer2_inode_xop_flush (backend).
 320  *
 321  * chain is locked on call and will remain locked on return.  The chain's
 322  * UPDATE flag indicates that its parent's block table (which is not yet
 323  * part of the flush) should be updated.  The chain may be replaced by
 324  * the call if it was modified.
 325  */
 326 void
 327 hammer2_flush(hammer2_chain_t *chain, int flags)
 328 {
 329         hammer2_chain_t *scan;
 330         hammer2_flush_info_t info;
 331         hammer2_dev_t *hmp;
 332         int loops;
 333
 334         /*
 335          * Execute the recursive flush and handle deferrals.
 336          *
 337          * Chains can be ridiculously long (thousands deep), so to
 338          * avoid blowing out the kernel stack the recursive flush has a
 339          * depth limit.  Elements at the limit are placed on a list
 340          * for re-execution after the stack has been popped.
 341          */
 342         bzero(&info, sizeof(info));
 343         TAILQ_INIT(&info.flushq);
 344         info.cache_index = -1;
 345         info.flags = flags & ~HAMMER2_FLUSH_TOP;
 346
 347         /*
 348          * Calculate parent (can be NULL), if not NULL the flush core
 349          * expects the parent to be referenced so it can easily lock/unlock
 350          * it without it getting ripped up.
 351          */
 352         if ((info.parent = chain->parent) != NULL)
 353                 hammer2_chain_ref(info.parent);
 354
 355         /*
 356          * Extra ref needed because flush_core expects it when replacing
 357          * chain.
 358          */
 359         hammer2_chain_ref(chain);
 360         hmp = chain->hmp;
 361         loops = 0;
 362
 363         for (;;) {
 364                 /*
 365                  * Move hmp->flushq to info.flushq if non-empty so it can
 366                  * be processed.
 367                  */
 368                 if (TAILQ_FIRST(&hmp->flushq) != NULL) {
 369                         hammer2_spin_ex(&chain->hmp->list_spin);
 370                         TAILQ_CONCAT(&info.flushq, &hmp->flushq, flush_node);
 371                         hammer2_spin_unex(&chain->hmp->list_spin);
 372                 }
 373
 374                 /*
 375                  * Unwind deep recursions which had been deferred.  This
 376                  * can leave the FLUSH_* bits set for these chains, which
 377                  * will be handled when we [re]flush chain after the unwind.
 378                  */
 379                 while ((scan = TAILQ_FIRST(&info.flushq)) != NULL) {
 380                         KKASSERT(scan->flags & HAMMER2_CHAIN_DEFERRED);
 381                         TAILQ_REMOVE(&info.flushq, scan, flush_node);
 382                         atomic_clear_int(&scan->flags, HAMMER2_CHAIN_DEFERRED |
 383                                                        HAMMER2_CHAIN_DELAYED);
 384
 385                         /*
 386                          * Now that we've popped back up we can do a secondary
 387                          * recursion on the deferred elements.
 388                          *
 389                          * NOTE: hammer2_flush() may replace scan.
 390                          */
 391                         if (hammer2_debug & 0x0040)
 392                                 kprintf("deferred flush %p\n", scan);
 393                         hammer2_chain_lock(scan, HAMMER2_RESOLVE_MAYBE);
 394                         hammer2_flush(scan, flags & ~HAMMER2_FLUSH_TOP);
 395                         hammer2_chain_unlock(scan);
 396                         hammer2_chain_drop(scan);       /* ref from deferral */
 397                 }
 398
 399                 /*
 400                  * [re]flush chain.
 401                  */
 402                 info.diddeferral = 0;
 403                 hammer2_flush_core(&info, chain, flags);
 404
 405                 /*
 406                  * Only loop if deep recursions have been deferred.
 407                  */
 408                 if (TAILQ_EMPTY(&info.flushq))
 409                         break;
 410
 411                 if (++loops % 1000 == 0) {
 412                         kprintf("hammer2_flush: excessive loops on %p\n",
 413                                 chain);
 414                         if (hammer2_debug & 0x100000)
 415                                 Debugger("hell4");
 416                 }
 417         }
 418         hammer2_chain_drop(chain);
 419         if (info.parent)
 420                 hammer2_chain_drop(info.parent);
 421 }
 422
 423 /*
 424  * This is the core of the chain flushing code.  The chain is locked by the
 425  * caller and must also have an extra ref on it by the caller, and remains
 426  * locked and will have an extra ref on return.  Upon return, the caller can
 427  * test the UPDATE bit on the child to determine if the parent needs updating.
 428  *
 429  * (1) Determine if this node is a candidate for the flush, return if it is
 430  *     not.  fchain and vchain are always candidates for the flush.
 431  *
 432  * (2) If we recurse too deep the chain is entered onto the deferral list and
 433  *     the current flush stack is aborted until after the deferral list is
 434  *     run.
 435  *
 436  * (3) Recursively flush live children (rbtree).  This can create deferrals.
 437  *     A successful flush clears the MODIFIED and UPDATE bits on the children
 438  *     and typically causes the parent to be marked MODIFIED as the children
 439  *     update the parent's block table.  A parent might already be marked
 440  *     MODIFIED due to a deletion (whos blocktable update in the parent is
 441  *     handled by the frontend), or if the parent itself is modified by the
 442  *     frontend for other reasons.
 443  *
 444  * (4) Permanently disconnected sub-trees are cleaned up by the front-end.
 445  *     Deleted-but-open inodes can still be individually flushed via the
 446  *     filesystem syncer.
 447  *
 448  * (5) Note that an unmodified child may still need the block table in its
 449  *     parent updated (e.g. rename/move).  The child will have UPDATE set
 450  *     in this case.
 451  *
 452  *                      WARNING ON BREF MODIFY_TID/MIRROR_TID
 453  *
 454  * blockref.modify_tid is consistent only within a PFS, and will not be
 455  * consistent during synchronization.  mirror_tid is consistent across the
 456  * block device regardless of the PFS.
 457  */
 458 static void
 459 hammer2_flush_core(hammer2_flush_info_t *info, hammer2_chain_t *chain,
 460                    int flags)
 461 {
 462         hammer2_chain_t *parent;
 463         hammer2_dev_t *hmp;
 464         int diddeferral;
 465
 466         /*
 467          * (1) Optimize downward recursion to locate nodes needing action.
 468          *     Nothing to do if none of these flags are set.
 469          */
 470         if ((chain->flags & HAMMER2_CHAIN_FLUSH_MASK) == 0) {
 471                 if (hammer2_debug & 0x200) {
 472                         if (info->debug == NULL)
 473                                 info->debug = chain;
 474                 } else {
 475                         return;
 476                 }
 477         }
 478
 479         hmp = chain->hmp;
 480         diddeferral = info->diddeferral;
 481         parent = info->parent;          /* can be NULL */
 482
 483         /*
 484          * Downward search recursion
 485          */
 486         if (chain->flags & (HAMMER2_CHAIN_DEFERRED | HAMMER2_CHAIN_DELAYED)) {
 487                 /*
 488                  * Already deferred.
 489                  */
 490                 ++info->diddeferral;
 491         } else if ((chain->flags & HAMMER2_CHAIN_PFSBOUNDARY) &&
 492                    (flags & HAMMER2_FLUSH_ALL) == 0 &&
 493                    (flags & HAMMER2_FLUSH_TOP) == 0) {
 494                 /*
 495                  * We do not recurse through PFSROOTs.  PFSROOT flushes are
 496                  * handled by the related pmp's (whether mounted or not,
 497                  * including during recovery).
 498                  *
 499                  * But we must still process the PFSROOT chains for block
 500                  * table updates in their parent (which IS part of our flush).
 501                  *
 502                  * Note that the volume root, vchain, does not set this flag.
 503                  * Note the logic here requires that this test be done before
 504                  * the depth-limit test, else it might become the top on a
 505                  * flushq iteration.
 506                  */
 507                 ;
 508         } else if (info->depth == HAMMER2_FLUSH_DEPTH_LIMIT) {
 509                 /*
 510                  * Recursion depth reached.
 511                  */
 512                 KKASSERT((chain->flags & HAMMER2_CHAIN_DELAYED) == 0);
 513                 hammer2_chain_ref(chain);
 514                 TAILQ_INSERT_TAIL(&info->flushq, chain, flush_node);
 515                 atomic_set_int(&chain->flags, HAMMER2_CHAIN_DEFERRED);
 516                 ++info->diddeferral;
 517         } else if (chain->flags & HAMMER2_CHAIN_ONFLUSH) {
 518                 /*
 519                  * Downward recursion search (actual flush occurs bottom-up).
 520                  * pre-clear ONFLUSH.  It can get set again due to races,
 521                  * which we want so the scan finds us again in the next flush.
 522                  */
 523                 atomic_clear_int(&chain->flags, HAMMER2_CHAIN_ONFLUSH);
 524                 info->parent = chain;
 525                 hammer2_spin_ex(&chain->core.spin);
 526                 RB_SCAN(hammer2_chain_tree, &chain->core.rbtree,
 527                         NULL, hammer2_flush_recurse, info);
 528                 hammer2_spin_unex(&chain->core.spin);
 529                 info->parent = parent;
 530                 if (info->diddeferral)
 531                         hammer2_chain_setflush(chain);
 532         }
 533
 534         /*
 535          * Now we are in the bottom-up part of the recursion.
 536          *
 537          * Do not update chain if lower layers were deferred.
 538          */
 539         if (info->diddeferral)
 540                 goto done;
 541
 542         /*
 543          * Propagate the DESTROY flag downwards.  This dummies up the flush
 544          * code and tries to invalidate related buffer cache buffers to
 545          * avoid the disk write.
 546          */
 547         if (parent && (parent->flags & HAMMER2_CHAIN_DESTROY))
 548                 atomic_set_int(&chain->flags, HAMMER2_CHAIN_DESTROY);
 549
 550         /*
 551          * Chain was already modified or has become modified, flush it out.
 552          */
 553 again:
 554         if ((hammer2_debug & 0x200) &&
 555             info->debug &&
 556             (chain->flags & (HAMMER2_CHAIN_MODIFIED | HAMMER2_CHAIN_UPDATE))) {
 557                 hammer2_chain_t *scan = chain;
 558
 559                 kprintf("DISCONNECTED FLUSH %p->%p\n", info->debug, chain);
 560                 while (scan) {
 561                         kprintf("    chain %p [%08x] bref=%016jx:%02x\n",
 562                                 scan, scan->flags,
 563                                 scan->bref.key, scan->bref.type);
 564                         if (scan == info->debug)
 565                                 break;
 566                         scan = scan->parent;
 567                 }
 568         }
 569
 570         if (chain->flags & HAMMER2_CHAIN_MODIFIED) {
 571                 /*
 572                  * Dispose of the modified bit.
 573                  *
 574                  * UPDATE should already be set.
 575                  * bref.mirror_tid should already be set.
 576                  */
 577                 KKASSERT((chain->flags & HAMMER2_CHAIN_UPDATE) ||
 578                          chain == &hmp->vchain);
 579                 atomic_clear_int(&chain->flags, HAMMER2_CHAIN_MODIFIED);
 580
 581                 /*
 582                  * Manage threads waiting for excessive dirty memory to
 583                  * be retired.
 584                  */
 585                 if (chain->pmp)
 586                         hammer2_pfs_memory_wakeup(chain->pmp);
 587
 588                 if ((chain->flags & HAMMER2_CHAIN_UPDATE) ||
 589                     chain == &hmp->vchain ||
 590                     chain == &hmp->fchain) {
 591                         /*
 592                          * Drop the ref from the MODIFIED bit we cleared,
 593                          * net -1 ref.
 594                          */
 595                         hammer2_chain_drop(chain);
 596                 } else {
 597                         /*
 598                          * Drop the ref from the MODIFIED bit we cleared and
 599                          * set a ref for the UPDATE bit we are setting.  Net
 600                          * 0 refs.
 601                          */
 602                         atomic_set_int(&chain->flags, HAMMER2_CHAIN_UPDATE);
 603                 }
 604
 605                 /*
 606                  * Issue the flush.  This is indirect via the DIO.
 607                  *
 608                  * NOTE: A DELETED node that reaches this point must be
 609                  *       flushed for synchronization point consistency.
 610                  *
 611                  * NOTE: Even though MODIFIED was already set, the related DIO
 612                  *       might not be dirty due to a system buffer cache
 613                  *       flush and must be set dirty if we are going to make
 614                  *       further modifications to the buffer.  Chains with
 615                  *       embedded data don't need this.
 616                  */
 617                 if (hammer2_debug & 0x1000) {
 618                         kprintf("Flush %p.%d %016jx/%d data=%016jx",
 619                                 chain, chain->bref.type,
 620                                 (uintmax_t)chain->bref.key,
 621                                 chain->bref.keybits,
 622                                 (uintmax_t)chain->bref.data_off);
 623                 }
 624                 if (hammer2_debug & 0x2000) {
 625                         Debugger("Flush hell");
 626                 }
 627
 628                 /*
 629                  * Update chain CRCs for flush.
 630                  *
 631                  * NOTE: Volume headers are NOT flushed here as they require
 632                  *       special processing.
 633                  */
 634                 switch(chain->bref.type) {
 635                 case HAMMER2_BREF_TYPE_FREEMAP:
 636                         /*
 637                          * Update the volume header's freemap_tid to the
 638                          * freemap's flushing mirror_tid.
 639                          *
 640                          * (note: embedded data, do not call setdirty)
 641                          */
 642                         KKASSERT(hmp->vchain.flags & HAMMER2_CHAIN_MODIFIED);
 643                         KKASSERT(chain == &hmp->fchain);
 644                         hmp->voldata.freemap_tid = chain->bref.mirror_tid;
 645                         if (hammer2_debug & 0x8000) {
 646                                 /* debug only, avoid syslogd loop */
 647                                 kprintf("sync freemap mirror_tid %08jx\n",
 648                                         (intmax_t)chain->bref.mirror_tid);
 649                         }
 650
 651                         /*
 652                          * The freemap can be flushed independently of the
 653                          * main topology, but for the case where it is
 654                          * flushed in the same transaction, and flushed
 655                          * before vchain (a case we want to allow for
 656                          * performance reasons), make sure modifications
 657                          * made during the flush under vchain use a new
 658                          * transaction id.
 659                          *
 660                          * Otherwise the mount recovery code will get confused.
 661                          */
 662                         ++hmp->voldata.mirror_tid;
 663                         break;
 664                 case HAMMER2_BREF_TYPE_VOLUME:
 665                         /*
 666                          * The free block table is flushed by
 667                          * hammer2_vfs_sync() before it flushes vchain.
 668                          * We must still hold fchain locked while copying
 669                          * voldata to volsync, however.
 670                          *
 671                          * (note: embedded data, do not call setdirty)
 672                          */
 673                         hammer2_chain_lock(&hmp->fchain,
 674                                            HAMMER2_RESOLVE_ALWAYS);
 675                         hammer2_voldata_lock(hmp);
 676                         if (hammer2_debug & 0x8000) {
 677                                 /* debug only, avoid syslogd loop */
 678                                 kprintf("sync volume  mirror_tid %08jx\n",
 679                                         (intmax_t)chain->bref.mirror_tid);
 680                         }
 681
 682                         /*
 683                          * Update the volume header's mirror_tid to the
 684                          * main topology's flushing mirror_tid.  It is
 685                          * possible that voldata.mirror_tid is already
 686                          * beyond bref.mirror_tid due to the bump we made
 687                          * above in BREF_TYPE_FREEMAP.
 688                          */
 689                         if (hmp->voldata.mirror_tid < chain->bref.mirror_tid) {
 690                                 hmp->voldata.mirror_tid =
 691                                         chain->bref.mirror_tid;
 692                         }
 693
 694                         /*
 695                          * The volume header is flushed manually by the
 696                          * syncer, not here.  All we do here is adjust the
 697                          * crc's.
 698                          */
 699                         KKASSERT(chain->data != NULL);
 700                         KKASSERT(chain->dio == NULL);
 701
 702                         hmp->voldata.icrc_sects[HAMMER2_VOL_ICRC_SECT1]=
 703                                 hammer2_icrc32(
 704                                         (char *)&hmp->voldata +
 705                                          HAMMER2_VOLUME_ICRC1_OFF,
 706                                         HAMMER2_VOLUME_ICRC1_SIZE);
 707                         hmp->voldata.icrc_sects[HAMMER2_VOL_ICRC_SECT0]=
 708                                 hammer2_icrc32(
 709                                         (char *)&hmp->voldata +
 710                                          HAMMER2_VOLUME_ICRC0_OFF,
 711                                         HAMMER2_VOLUME_ICRC0_SIZE);
 712                         hmp->voldata.icrc_volheader =
 713                                 hammer2_icrc32(
 714                                         (char *)&hmp->voldata +
 715                                          HAMMER2_VOLUME_ICRCVH_OFF,
 716                                         HAMMER2_VOLUME_ICRCVH_SIZE);
 717
 718                         if (hammer2_debug & 0x8000) {
 719                                 /* debug only, avoid syslogd loop */
 720                                 kprintf("syncvolhdr %016jx %016jx\n",
 721                                         hmp->voldata.mirror_tid,
 722                                         hmp->vchain.bref.mirror_tid);
 723                         }
 724                         hmp->volsync = hmp->voldata;
 725                         atomic_set_int(&chain->flags, HAMMER2_CHAIN_VOLUMESYNC);
 726                         hammer2_voldata_unlock(hmp);
 727                         hammer2_chain_unlock(&hmp->fchain);
 728                         break;
 729                 case HAMMER2_BREF_TYPE_DATA:
 730                         /*
 731                          * Data elements have already been flushed via the
 732                          * logical file buffer cache.  Their hash was set in
 733                          * the bref by the vop_write code.  Do not re-dirty.
 734                          *
 735                          * Make sure any device buffer(s) have been flushed
 736                          * out here (there aren't usually any to flush) XXX.
 737                          */
 738                         break;
 739                 case HAMMER2_BREF_TYPE_INDIRECT:
 740                 case HAMMER2_BREF_TYPE_FREEMAP_NODE:
 741                 case HAMMER2_BREF_TYPE_FREEMAP_LEAF:
 742                         /*
 743                          * Buffer I/O will be cleaned up when the volume is
 744                          * flushed (but the kernel is free to flush it before
 745                          * then, as well).
 746                          */
 747                         KKASSERT((chain->flags & HAMMER2_CHAIN_EMBEDDED) == 0);
 748                         hammer2_chain_setcheck(chain, chain->data);
 749                         break;
 750                 case HAMMER2_BREF_TYPE_INODE:
 751                         /*
 752                          * NOTE: We must call io_setdirty() to make any late
 753                          *       changes to the inode data, the system might
 754                          *       have already flushed the buffer.
 755                          */
 756                         if (chain->data->ipdata.meta.op_flags &
 757                             HAMMER2_OPFLAG_PFSROOT) {
 758                                 /*
 759                                  * non-NULL pmp if mounted as a PFS.  We must
 760                                  * sync fields cached in the pmp? XXX
 761                                  */
 762                                 hammer2_inode_data_t *ipdata;
 763
 764                                 hammer2_io_setdirty(chain->dio);
 765                                 ipdata = &chain->data->ipdata;
 766                                 if (chain->pmp) {
 767                                         ipdata->meta.pfs_inum =
 768                                                 chain->pmp->inode_tid;
 769                                 }
 770                         } else {
 771                                 /* can't be mounted as a PFS */
 772                         }
 773
 774                         KKASSERT((chain->flags & HAMMER2_CHAIN_EMBEDDED) == 0);
 775                         hammer2_chain_setcheck(chain, chain->data);
 776                         break;
 777                 default:
 778                         KKASSERT(chain->flags & HAMMER2_CHAIN_EMBEDDED);
 779                         panic("hammer2_flush_core: unsupported "
 780                               "embedded bref %d",
 781                               chain->bref.type);
 782                         /* NOT REACHED */
 783                 }
 784
 785                 /*
 786                  * If the chain was destroyed try to avoid unnecessary I/O.
 787                  * (this only really works if the DIO system buffer is the
 788                  * same size as chain->bytes).
 789                  */
 790                 if ((chain->flags & HAMMER2_CHAIN_DESTROY) &&
 791                     (chain->flags & HAMMER2_CHAIN_DEDUP) == 0 &&
 792                     chain->dio) {
 793                         hammer2_io_setinval(chain->dio, chain->bytes);
 794                 }
 795         }
 796
 797         /*
 798          * If UPDATE is set the parent block table may need to be updated.
 799          *
 800          * NOTE: UPDATE may be set on vchain or fchain in which case
 801          *       parent could be NULL.  It's easiest to allow the case
 802          *       and test for NULL.  parent can also wind up being NULL
 803          *       due to a deletion so we need to handle the case anyway.
 804          *
 805          * If no parent exists we can just clear the UPDATE bit.  If the
 806          * chain gets reattached later on the bit will simply get set
 807          * again.
 808          */
 809         if ((chain->flags & HAMMER2_CHAIN_UPDATE) && parent == NULL) {
 810                 atomic_clear_int(&chain->flags, HAMMER2_CHAIN_UPDATE);
 811                 hammer2_chain_drop(chain);
 812         }
 813
 814         /*
 815          * The chain may need its blockrefs updated in the parent.  This
 816          * requires some fancy footwork.
 817          */
 818         if (chain->flags & HAMMER2_CHAIN_UPDATE) {
 819                 hammer2_blockref_t *base;
 820                 int count;
 821
 822                 /*
 823                  * Both parent and chain must be locked.  This requires
 824                  * temporarily unlocking the chain.  We have to deal with
 825                  * the case where the chain might be reparented or modified
 826                  * while it was unlocked.
 827                  */
 828                 hammer2_chain_unlock(chain);
 829                 hammer2_chain_lock(parent, HAMMER2_RESOLVE_ALWAYS);
 830                 hammer2_chain_lock(chain, HAMMER2_RESOLVE_MAYBE);
 831                 if (chain->parent != parent) {
 832                         kprintf("PARENT MISMATCH ch=%p p=%p/%p\n",
 833                                 chain, chain->parent, parent);
 834                         hammer2_chain_unlock(parent);
 835                         goto done;
 836                 }
 837
 838                 /*
 839                  * Check race condition.  If someone got in and modified
 840                  * it again while it was unlocked, we have to loop up.
 841                  */
 842                 if (chain->flags & HAMMER2_CHAIN_MODIFIED) {
 843                         hammer2_chain_unlock(parent);
 844                         kprintf("hammer2_flush: chain %p flush-mod race\n",
 845                                 chain);
 846                         goto again;
 847                 }
 848
 849                 /*
 850                  * Clear UPDATE flag, mark parent modified, update its
 851                  * modify_tid if necessary, and adjust the parent blockmap.
 852                  */
 853                 if (chain->flags & HAMMER2_CHAIN_UPDATE) {
 854                         atomic_clear_int(&chain->flags, HAMMER2_CHAIN_UPDATE);
 855                         hammer2_chain_drop(chain);
 856                 }
 857
 858                 /*
 859                  * (optional code)
 860                  *
 861                  * Avoid actually modifying and updating the parent if it
 862                  * was flagged for destruction.  This can greatly reduce
 863                  * disk I/O in large tree removals because the
 864                  * hammer2_io_setinval() call in the upward recursion
 865                  * (see MODIFIED code above) can only handle a few cases.
 866                  */
 867                 if (parent->flags & HAMMER2_CHAIN_DESTROY) {
 868                         if (parent->bref.modify_tid < chain->bref.modify_tid) {
 869                                 parent->bref.modify_tid =
 870                                         chain->bref.modify_tid;
 871                         }
 872                         atomic_clear_int(&chain->flags, HAMMER2_CHAIN_BMAPPED |
 873                                                         HAMMER2_CHAIN_BMAPUPD);
 874                         hammer2_chain_unlock(parent);
 875                         goto skipupdate;
 876                 }
 877
 878                 /*
 879                  * We are updating the parent's blockmap, the parent must
 880                  * be set modified.
 881                  */
 882                 hammer2_chain_modify(parent, 0, 0, 0);
 883                 if (parent->bref.modify_tid < chain->bref.modify_tid)
 884                         parent->bref.modify_tid = chain->bref.modify_tid;
 885
 886                 /*
 887                  * Calculate blockmap pointer
 888                  */
 889                 switch(parent->bref.type) {
 890                 case HAMMER2_BREF_TYPE_INODE:
 891                         /*
 892                          * Access the inode's block array.  However, there is
 893                          * no block array if the inode is flagged DIRECTDATA.
 894                          */
 895                         if (parent->data &&
 896                             (parent->data->ipdata.meta.op_flags &
 897                              HAMMER2_OPFLAG_DIRECTDATA) == 0) {
 898                                 base = &parent->data->
 899                                         ipdata.u.blockset.blockref[0];
 900                         } else {
 901                                 base = NULL;
 902                         }
 903                         count = HAMMER2_SET_COUNT;
 904                         break;
 905                 case HAMMER2_BREF_TYPE_INDIRECT:
 906                 case HAMMER2_BREF_TYPE_FREEMAP_NODE:
 907                         if (parent->data)
 908                                 base = &parent->data->npdata[0];
 909                         else
 910                                 base = NULL;
 911                         count = parent->bytes / sizeof(hammer2_blockref_t);
 912                         break;
 913                 case HAMMER2_BREF_TYPE_VOLUME:
 914                         base = &chain->hmp->voldata.sroot_blockset.blockref[0];
 915                         count = HAMMER2_SET_COUNT;
 916                         break;
 917                 case HAMMER2_BREF_TYPE_FREEMAP:
 918                         base = &parent->data->npdata[0];
 919                         count = HAMMER2_SET_COUNT;
 920                         break;
 921                 default:
 922                         base = NULL;
 923                         count = 0;
 924                         panic("hammer2_flush_core: "
 925                               "unrecognized blockref type: %d",
 926                               parent->bref.type);
 927                 }
 928
 929                 /*
 930                  * Blocktable updates
 931                  *
 932                  * We synchronize pending statistics at this time.  Delta
 933                  * adjustments designated for the current and upper level
 934                  * are synchronized.
 935                  */
 936                 if (base && (chain->flags & HAMMER2_CHAIN_BMAPUPD)) {
 937                         if (chain->flags & HAMMER2_CHAIN_BMAPPED) {
 938                                 hammer2_spin_ex(&parent->core.spin);
 939                                 hammer2_base_delete(parent, base, count,
 940                                                     &info->cache_index, chain);
 941                                 hammer2_spin_unex(&parent->core.spin);
 942                                 /* base_delete clears both bits */
 943                         } else {
 944                                 atomic_clear_int(&chain->flags,
 945                                                  HAMMER2_CHAIN_BMAPUPD);
 946                         }
 947                 }
 948                 if (base && (chain->flags & HAMMER2_CHAIN_BMAPPED) == 0) {
 949                         hammer2_spin_ex(&parent->core.spin);
 950                         hammer2_base_insert(parent, base, count,
 951                                             &info->cache_index, chain);
 952                         hammer2_spin_unex(&parent->core.spin);
 953                         /* base_insert sets BMAPPED */
 954                 }
 955                 hammer2_chain_unlock(parent);
 956         }
 957 skipupdate:
 958         ;
 959
 960         /*
 961          * Final cleanup after flush
 962          */
 963 done:
 964         KKASSERT(chain->refs > 0);
 965         if (hammer2_debug & 0x200) {
 966                 if (info->debug == chain)
 967                         info->debug = NULL;
 968         }
 969 }
 970
 971 /*
 972  * Flush recursion helper, called from flush_core, calls flush_core.
 973  *
 974  * Flushes the children of the caller's chain (info->parent), restricted
 975  * by sync_tid.  Set info->domodify if the child's blockref must propagate
 976  * back up to the parent.
 977  *
 978  * Ripouts can move child from rbtree to dbtree or dbq but the caller's
 979  * flush scan order prevents any chains from being lost.  A child can be
 980  * executes more than once.
 981  *
 982  * WARNING! If we do not call hammer2_flush_core() we must update
 983  *          bref.mirror_tid ourselves to indicate that the flush has
 984  *          processed the child.
 985  *
 986  * WARNING! parent->core spinlock is held on entry and return.
 987  */
 988 static int
 989 hammer2_flush_recurse(hammer2_chain_t *child, void *data)
 990 {
 991         hammer2_flush_info_t *info = data;
 992         hammer2_chain_t *parent = info->parent;
 993
 994         /*
 995          * (child can never be fchain or vchain so a special check isn't
 996          *  needed).
 997          *
 998          * We must ref the child before unlocking the spinlock.
 999          *
1000          * The caller has added a ref to the parent so we can temporarily
1001          * unlock it in order to lock the child.
1002          */
1003         hammer2_chain_ref(child);
1004         hammer2_spin_unex(&parent->core.spin);
1005
1006         hammer2_chain_unlock(parent);
1007         hammer2_chain_lock(child, HAMMER2_RESOLVE_MAYBE);
1008
1009         /*
1010          * Recurse and collect deferral data.  We're in the media flush,
1011          * this can cross PFS boundaries.
1012          */
1013         if (child->flags & HAMMER2_CHAIN_FLUSH_MASK) {
1014                 ++info->depth;
1015                 hammer2_flush_core(info, child, info->flags);
1016                 --info->depth;
1017         } else if (hammer2_debug & 0x200) {
1018                 if (info->debug == NULL)
1019                         info->debug = child;
1020                 ++info->depth;
1021                 hammer2_flush_core(info, child, info->flags);
1022                 --info->depth;
1023                 if (info->debug == child)
1024                         info->debug = NULL;
1025         }
1026
1027         /*
1028          * Relock to continue the loop
1029          */
1030         hammer2_chain_unlock(child);
1031         hammer2_chain_lock(parent, HAMMER2_RESOLVE_MAYBE);
1032         hammer2_chain_drop(child);
1033         KKASSERT(info->parent == parent);
1034         hammer2_spin_ex(&parent->core.spin);
1035
1036         return (0);
1037 }
1038
1039 /*
1040  * flush helper (direct)
1041  *
1042  * Quickly flushes any dirty chains for a device.  This will update our
1043  * concept of the volume root but does NOT flush the actual volume root
1044  * and does not flush dirty device buffers.
1045  *
1046  * This function is primarily used by the bulkfree code to allow it to
1047  * create a snapshot for the pass.  It doesn't care about any pending
1048  * work (dirty vnodes, dirty inodes, dirty logical buffers) for which blocks
1049  * have not yet been allocated.
1050  */
1051 void
1052 hammer2_flush_quick(hammer2_dev_t *hmp)
1053 {
1054         hammer2_chain_t *chain;
1055
1056         hammer2_trans_init(hmp->spmp, HAMMER2_TRANS_ISFLUSH);
1057
1058         hammer2_chain_ref(&hmp->vchain);
1059         hammer2_chain_lock(&hmp->vchain, HAMMER2_RESOLVE_ALWAYS);
1060         if (hmp->vchain.flags & HAMMER2_CHAIN_FLUSH_MASK) {
1061                 chain = &hmp->vchain;
1062                 hammer2_flush(chain, HAMMER2_FLUSH_TOP |
1063                                      HAMMER2_FLUSH_ALL);
1064                 KKASSERT(chain == &hmp->vchain);
1065         }
1066         hammer2_chain_unlock(&hmp->vchain);
1067         hammer2_chain_drop(&hmp->vchain);
1068
1069         hammer2_trans_done(hmp->spmp);  /* spmp trans */
1070 }
1071
1072 /*
1073  * flush helper (backend threaded)
1074  *
1075  * Flushes core chains, issues disk sync, flushes volume roots.
1076  *
1077  * Primarily called from vfs_sync().
1078  */
1079 void
1080 hammer2_inode_xop_flush(hammer2_xop_t *arg, int clindex)
1081 {
1082         hammer2_xop_flush_t *xop = &arg->xop_flush;
1083         hammer2_chain_t *chain;
1084         hammer2_chain_t *parent;
1085         hammer2_dev_t *hmp;
1086         int error = 0;
1087         int total_error = 0;
1088         int j;
1089
1090         /*
1091          * Flush core chains
1092          */
1093         chain = hammer2_inode_chain(xop->head.ip1, clindex,
1094                                     HAMMER2_RESOLVE_ALWAYS);
1095         if (chain) {
1096                 hmp = chain->hmp;
1097                 if (chain->flags & HAMMER2_CHAIN_FLUSH_MASK) {
1098                         hammer2_flush(chain, HAMMER2_FLUSH_TOP);
1099                         parent = chain->parent;
1100                         KKASSERT(chain->pmp != parent->pmp);
1101                         hammer2_chain_setflush(parent);
1102                 }
1103                 hammer2_chain_unlock(chain);
1104                 hammer2_chain_drop(chain);
1105                 chain = NULL;
1106         } else {
1107                 hmp = NULL;
1108         }
1109
1110         /*
1111          * Flush volume roots.  Avoid replication, we only want to
1112          * flush each hammer2_dev (hmp) once.
1113          */
1114         for (j = clindex - 1; j >= 0; --j) {
1115                 if ((chain = xop->head.ip1->cluster.array[j].chain) != NULL) {
1116                         if (chain->hmp == hmp) {
1117                                 chain = NULL;   /* safety */
1118                                 goto skip;
1119                         }
1120                 }
1121         }
1122         chain = NULL;   /* safety */
1123
1124         /*
1125          * spmp transaction.  The super-root is never directly mounted so
1126          * there shouldn't be any vnodes, let alone any dirty vnodes
1127          * associated with it, so we shouldn't have to mess around with any
1128          * vnode flushes here.
1129          */
1130         hammer2_trans_init(hmp->spmp, HAMMER2_TRANS_ISFLUSH);
1131
1132         /*
1133          * Media mounts have two 'roots', vchain for the topology
1134          * and fchain for the free block table.  Flush both.
1135          *
1136          * Note that the topology and free block table are handled
1137          * independently, so the free block table can wind up being
1138          * ahead of the topology.  We depend on the bulk free scan
1139          * code to deal with any loose ends.
1140          */
1141         hammer2_chain_ref(&hmp->vchain);
1142         hammer2_chain_lock(&hmp->vchain, HAMMER2_RESOLVE_ALWAYS);
1143         hammer2_chain_ref(&hmp->fchain);
1144         hammer2_chain_lock(&hmp->fchain, HAMMER2_RESOLVE_ALWAYS);
1145         if (hmp->fchain.flags & HAMMER2_CHAIN_FLUSH_MASK) {
1146                 /*
1147                  * This will also modify vchain as a side effect,
1148                  * mark vchain as modified now.
1149                  */
1150                 hammer2_voldata_modify(hmp);
1151                 chain = &hmp->fchain;
1152                 hammer2_flush(chain, HAMMER2_FLUSH_TOP);
1153                 KKASSERT(chain == &hmp->fchain);
1154         }
1155         hammer2_chain_unlock(&hmp->fchain);
1156         hammer2_chain_unlock(&hmp->vchain);
1157         hammer2_chain_drop(&hmp->fchain);
1158         /* vchain dropped down below */
1159
1160         hammer2_chain_lock(&hmp->vchain, HAMMER2_RESOLVE_ALWAYS);
1161         if (hmp->vchain.flags & HAMMER2_CHAIN_FLUSH_MASK) {
1162                 chain = &hmp->vchain;
1163                 hammer2_flush(chain, HAMMER2_FLUSH_TOP);
1164                 KKASSERT(chain == &hmp->vchain);
1165         }
1166         hammer2_chain_unlock(&hmp->vchain);
1167         hammer2_chain_drop(&hmp->vchain);
1168
1169         error = 0;
1170
1171         /*
1172          * We can't safely flush the volume header until we have
1173          * flushed any device buffers which have built up.
1174          *
1175          * XXX this isn't being incremental
1176          */
1177         vn_lock(hmp->devvp, LK_EXCLUSIVE | LK_RETRY);
1178         error = VOP_FSYNC(hmp->devvp, MNT_WAIT, 0);
1179         vn_unlock(hmp->devvp);
1180
1181         /*
1182          * The flush code sets CHAIN_VOLUMESYNC to indicate that the
1183          * volume header needs synchronization via hmp->volsync.
1184          *
1185          * XXX synchronize the flag & data with only this flush XXX
1186          */
1187         if (error == 0 &&
1188             (hmp->vchain.flags & HAMMER2_CHAIN_VOLUMESYNC)) {
1189                 struct buf *bp;
1190
1191                 /*
1192                  * Synchronize the disk before flushing the volume
1193                  * header.
1194                  */
1195                 bp = getpbuf(NULL);
1196                 bp->b_bio1.bio_offset = 0;
1197                 bp->b_bufsize = 0;
1198                 bp->b_bcount = 0;
1199                 bp->b_cmd = BUF_CMD_FLUSH;
1200                 bp->b_bio1.bio_done = biodone_sync;
1201                 bp->b_bio1.bio_flags |= BIO_SYNC;
1202                 vn_strategy(hmp->devvp, &bp->b_bio1);
1203                 biowait(&bp->b_bio1, "h2vol");
1204                 relpbuf(bp, NULL);
1205
1206                 /*
1207                  * Then we can safely flush the version of the
1208                  * volume header synchronized by the flush code.
1209                  */
1210                 j = hmp->volhdrno + 1;
1211                 if (j >= HAMMER2_NUM_VOLHDRS)
1212                         j = 0;
1213                 if (j * HAMMER2_ZONE_BYTES64 + HAMMER2_SEGSIZE >
1214                     hmp->volsync.volu_size) {
1215                         j = 0;
1216                 }
1217                 if (hammer2_debug & 0x8000) {
1218                         /* debug only, avoid syslogd loop */
1219                         kprintf("sync volhdr %d %jd\n",
1220                                 j, (intmax_t)hmp->volsync.volu_size);
1221                 }
1222                 bp = getblk(hmp->devvp, j * HAMMER2_ZONE_BYTES64,
1223                             HAMMER2_PBUFSIZE, 0, 0);
1224                 atomic_clear_int(&hmp->vchain.flags,
1225                                  HAMMER2_CHAIN_VOLUMESYNC);
1226                 bcopy(&hmp->volsync, bp->b_data, HAMMER2_PBUFSIZE);
1227                 bawrite(bp);
1228                 hmp->volhdrno = j;
1229         }
1230         if (error)
1231                 total_error = error;
1232
1233         hammer2_trans_done(hmp->spmp);  /* spmp trans */
1234 skip:
1235         error = hammer2_xop_feed(&xop->head, NULL, clindex, total_error);
1236 }