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                          * Afterwords, normal transactions will be
 137                          * interlocked.
 138                          */
 139                         if (oflags & HAMMER2_TRANS_MASK) {
 140                                 nflags = oflags | HAMMER2_TRANS_FPENDING |
 141                                                   HAMMER2_TRANS_WAITING;
 142                                 dowait = 1;
 143                         } else {
 144                                 nflags = (oflags | flags) + 1;
 145                         }
 146                 } else if (flags & HAMMER2_TRANS_BUFCACHE) {
 147                         /*
 148                          * Requesting strategy transaction from buffer-cache,
 149                          * or a VM getpages/putpages through the buffer cache.
 150                          * We must allow such transactions in all situations
 151                          * to avoid deadlocks.
 152                          */
 153                         nflags = (oflags | flags) + 1;
 154 #if 0
 155                         /*
 156                          * (old) previous code interlocked against the main
 157                          *       flush pass.
 158                          */
 159                         if ((oflags & (HAMMER2_TRANS_ISFLUSH |
 160                                        HAMMER2_TRANS_PREFLUSH)) ==
 161                             HAMMER2_TRANS_ISFLUSH) {
 162                                 nflags = oflags | HAMMER2_TRANS_WAITING;
 163                                 dowait = 1;
 164                         } else {
 165                                 nflags = (oflags | flags) + 1;
 166                         }
 167 #endif
 168                 } else {
 169                         /*
 170                          * Requesting normal modifying transaction (read-only
 171                          * operations do not use transactions).  Waits for
 172                          * any flush to finish before allowing.  Multiple
 173                          * modifying transactions can run concurrently.
 174                          */
 175                         if (oflags & HAMMER2_TRANS_ISFLUSH) {
 176                                 nflags = oflags | HAMMER2_TRANS_WAITING;
 177                                 dowait = 1;
 178                         } else {
 179                                 nflags = (oflags | flags) + 1;
 180                         }
 181                 }
 182                 if (dowait)
 183                         tsleep_interlock(&pmp->trans.sync_wait, 0);
 184                 if (atomic_cmpset_int(&pmp->trans.flags, oflags, nflags)) {
 185                         if (dowait == 0)
 186                                 break;
 187                         tsleep(&pmp->trans.sync_wait, PINTERLOCKED,
 188                                "h2trans", hz);
 189                 } else {
 190                         cpu_pause();
 191                 }
 192                 /* retry */
 193         }
 194 }
 195
 196 /*
 197  * Start a sub-transaction, there is no 'subdone' function.  This will
 198  * issue a new modify_tid (mtid) for the current transaction, which is a
 199  * CLC (cluster level change) id and not a per-node id.
 200  *
 201  * This function must be called for each XOP when multiple XOPs are run in
 202  * sequence within a transaction.
 203  *
 204  * Callers typically update the inode with the transaction mtid manually
 205  * to enforce sequencing.
 206  */
 207 hammer2_tid_t
 208 hammer2_trans_sub(hammer2_pfs_t *pmp)
 209 {
 210         hammer2_tid_t mtid;
 211
 212         mtid = atomic_fetchadd_64(&pmp->modify_tid, 1);
 213
 214         return (mtid);
 215 }
 216
 217 void
 218 hammer2_trans_done(hammer2_pfs_t *pmp)
 219 {
 220         uint32_t oflags;
 221         uint32_t nflags;
 222
 223         for (;;) {
 224                 oflags = pmp->trans.flags;
 225                 cpu_ccfence();
 226                 KKASSERT(oflags & HAMMER2_TRANS_MASK);
 227                 if ((oflags & HAMMER2_TRANS_MASK) == 1) {
 228                         /*
 229                          * This was the last transaction
 230                          */
 231                         nflags = (oflags - 1) & ~(HAMMER2_TRANS_ISFLUSH |
 232                                                   HAMMER2_TRANS_BUFCACHE |
 233                                                   HAMMER2_TRANS_FPENDING |
 234                                                   HAMMER2_TRANS_WAITING);
 235                 } else {
 236                         /*
 237                          * Still transactions pending
 238                          */
 239                         nflags = oflags - 1;
 240                 }
 241                 if (atomic_cmpset_int(&pmp->trans.flags, oflags, nflags)) {
 242                         if ((nflags & HAMMER2_TRANS_MASK) == 0 &&
 243                             (oflags & HAMMER2_TRANS_WAITING)) {
 244                                 wakeup(&pmp->trans.sync_wait);
 245                         }
 246                         break;
 247                 } else {
 248                         cpu_pause();
 249                 }
 250                 /* retry */
 251         }
 252 }
 253
 254 /*
 255  * Obtain new, unique inode number (not serialized by caller).
 256  */
 257 hammer2_tid_t
 258 hammer2_trans_newinum(hammer2_pfs_t *pmp)
 259 {
 260         hammer2_tid_t tid;
 261
 262         tid = atomic_fetchadd_64(&pmp->inode_tid, 1);
 263
 264         return tid;
 265 }
 266
 267 /*
 268  * Assert that a strategy call is ok here.  Currently we allow strategy
 269  * calls in all situations, including during flushes.  Previously:
 270  *      (old) (1) In a normal transaction.
 271  *      (old) (2) In a flush transaction only if PREFLUSH is also set.
 272  */
 273 void
 274 hammer2_trans_assert_strategy(hammer2_pfs_t *pmp)
 275 {
 276 #if 0
 277         KKASSERT((pmp->trans.flags & HAMMER2_TRANS_ISFLUSH) == 0 ||
 278                  (pmp->trans.flags & HAMMER2_TRANS_PREFLUSH));
 279 #endif
 280 }
 281
 282
 283 /*
 284  * Chains undergoing destruction are removed from the in-memory topology.
 285  * To avoid getting lost these chains are placed on the delayed flush
 286  * queue which will properly dispose of them.
 287  *
 288  * We do this instead of issuing an immediate flush in order to give
 289  * recursive deletions (rm -rf, etc) a chance to remove more of the
 290  * hierarchy, potentially allowing an enormous amount of write I/O to
 291  * be avoided.
 292  */
 293 void
 294 hammer2_delayed_flush(hammer2_chain_t *chain)
 295 {
 296         if ((chain->flags & HAMMER2_CHAIN_DELAYED) == 0) {
 297                 hammer2_spin_ex(&chain->hmp->list_spin);
 298                 if ((chain->flags & (HAMMER2_CHAIN_DELAYED |
 299                                      HAMMER2_CHAIN_DEFERRED)) == 0) {
 300                         atomic_set_int(&chain->flags, HAMMER2_CHAIN_DELAYED |
 301                                                       HAMMER2_CHAIN_DEFERRED);
 302                         TAILQ_INSERT_TAIL(&chain->hmp->flushq,
 303                                           chain, flush_node);
 304                         hammer2_chain_ref(chain);
 305                 }
 306                 hammer2_spin_unex(&chain->hmp->list_spin);
 307                 hammer2_voldata_modify(chain->hmp);
 308         }
 309 }
 310
 311 /*
 312  * Flush the chain and all modified sub-chains through the specified
 313  * synchronization point, propagating blockref updates back up.  As
 314  * part of this propagation, mirror_tid and inode/data usage statistics
 315  * propagates back upward.
 316  *
 317  * modify_tid (clc - cluster level change) is not propagated.
 318  *
 319  * update_tid (clc) is used for validation and is not propagated by this
 320  * function.
 321  *
 322  * This routine can be called from several places but the most important
 323  * is from VFS_SYNC (frontend) via hammer2_inode_xop_flush (backend).
 324  *
 325  * chain is locked on call and will remain locked on return.  The chain's
 326  * UPDATE flag indicates that its parent's block table (which is not yet
 327  * part of the flush) should be updated.  The chain may be replaced by
 328  * the call if it was modified.
 329  */
 330 void
 331 hammer2_flush(hammer2_chain_t *chain, int flags)
 332 {
 333         hammer2_chain_t *scan;
 334         hammer2_flush_info_t info;
 335         hammer2_dev_t *hmp;
 336         int loops;
 337
 338         /*
 339          * Execute the recursive flush and handle deferrals.
 340          *
 341          * Chains can be ridiculously long (thousands deep), so to
 342          * avoid blowing out the kernel stack the recursive flush has a
 343          * depth limit.  Elements at the limit are placed on a list
 344          * for re-execution after the stack has been popped.
 345          */
 346         bzero(&info, sizeof(info));
 347         TAILQ_INIT(&info.flushq);
 348         info.cache_index = -1;
 349         info.flags = flags & ~HAMMER2_FLUSH_TOP;
 350
 351         /*
 352          * Calculate parent (can be NULL), if not NULL the flush core
 353          * expects the parent to be referenced so it can easily lock/unlock
 354          * it without it getting ripped up.
 355          */
 356         if ((info.parent = chain->parent) != NULL)
 357                 hammer2_chain_ref(info.parent);
 358
 359         /*
 360          * Extra ref needed because flush_core expects it when replacing
 361          * chain.
 362          */
 363         hammer2_chain_ref(chain);
 364         hmp = chain->hmp;
 365         loops = 0;
 366
 367         for (;;) {
 368                 /*
 369                  * Move hmp->flushq to info.flushq if non-empty so it can
 370                  * be processed.
 371                  */
 372                 if (TAILQ_FIRST(&hmp->flushq) != NULL) {
 373                         hammer2_spin_ex(&chain->hmp->list_spin);
 374                         TAILQ_CONCAT(&info.flushq, &hmp->flushq, flush_node);
 375                         hammer2_spin_unex(&chain->hmp->list_spin);
 376                 }
 377
 378                 /*
 379                  * Unwind deep recursions which had been deferred.  This
 380                  * can leave the FLUSH_* bits set for these chains, which
 381                  * will be handled when we [re]flush chain after the unwind.
 382                  */
 383                 while ((scan = TAILQ_FIRST(&info.flushq)) != NULL) {
 384                         KKASSERT(scan->flags & HAMMER2_CHAIN_DEFERRED);
 385                         TAILQ_REMOVE(&info.flushq, scan, flush_node);
 386                         atomic_clear_int(&scan->flags, HAMMER2_CHAIN_DEFERRED |
 387                                                        HAMMER2_CHAIN_DELAYED);
 388
 389                         /*
 390                          * Now that we've popped back up we can do a secondary
 391                          * recursion on the deferred elements.
 392                          *
 393                          * NOTE: hammer2_flush() may replace scan.
 394                          */
 395                         if (hammer2_debug & 0x0040)
 396                                 kprintf("deferred flush %p\n", scan);
 397                         hammer2_chain_lock(scan, HAMMER2_RESOLVE_MAYBE);
 398                         hammer2_flush(scan, flags & ~HAMMER2_FLUSH_TOP);
 399                         hammer2_chain_unlock(scan);
 400                         hammer2_chain_drop(scan);       /* ref from deferral */
 401                 }
 402
 403                 /*
 404                  * [re]flush chain.
 405                  */
 406                 info.diddeferral = 0;
 407                 hammer2_flush_core(&info, chain, flags);
 408
 409                 /*
 410                  * Only loop if deep recursions have been deferred.
 411                  */
 412                 if (TAILQ_EMPTY(&info.flushq))
 413                         break;
 414
 415                 if (++loops % 1000 == 0) {
 416                         kprintf("hammer2_flush: excessive loops on %p\n",
 417                                 chain);
 418                         if (hammer2_debug & 0x100000)
 419                                 Debugger("hell4");
 420                 }
 421         }
 422         hammer2_chain_drop(chain);
 423         if (info.parent)
 424                 hammer2_chain_drop(info.parent);
 425 }
 426
 427 /*
 428  * This is the core of the chain flushing code.  The chain is locked by the
 429  * caller and must also have an extra ref on it by the caller, and remains
 430  * locked and will have an extra ref on return.  Upon return, the caller can
 431  * test the UPDATE bit on the child to determine if the parent needs updating.
 432  *
 433  * (1) Determine if this node is a candidate for the flush, return if it is
 434  *     not.  fchain and vchain are always candidates for the flush.
 435  *
 436  * (2) If we recurse too deep the chain is entered onto the deferral list and
 437  *     the current flush stack is aborted until after the deferral list is
 438  *     run.
 439  *
 440  * (3) Recursively flush live children (rbtree).  This can create deferrals.
 441  *     A successful flush clears the MODIFIED and UPDATE bits on the children
 442  *     and typically causes the parent to be marked MODIFIED as the children
 443  *     update the parent's block table.  A parent might already be marked
 444  *     MODIFIED due to a deletion (whos blocktable update in the parent is
 445  *     handled by the frontend), or if the parent itself is modified by the
 446  *     frontend for other reasons.
 447  *
 448  * (4) Permanently disconnected sub-trees are cleaned up by the front-end.
 449  *     Deleted-but-open inodes can still be individually flushed via the
 450  *     filesystem syncer.
 451  *
 452  * (5) Delete parents on the way back up if they are normal indirect blocks
 453  *     and have no children.
 454  *
 455  * (6) Note that an unmodified child may still need the block table in its
 456  *     parent updated (e.g. rename/move).  The child will have UPDATE set
 457  *     in this case.
 458  *
 459  *                      WARNING ON BREF MODIFY_TID/MIRROR_TID
 460  *
 461  * blockref.modify_tid is consistent only within a PFS, and will not be
 462  * consistent during synchronization.  mirror_tid is consistent across the
 463  * block device regardless of the PFS.
 464  */
 465 static void
 466 hammer2_flush_core(hammer2_flush_info_t *info, hammer2_chain_t *chain,
 467                    int flags)
 468 {
 469         hammer2_chain_t *parent;
 470         hammer2_dev_t *hmp;
 471         int diddeferral;
 472
 473         /*
 474          * (1) Optimize downward recursion to locate nodes needing action.
 475          *     Nothing to do if none of these flags are set.
 476          */
 477         if ((chain->flags & HAMMER2_CHAIN_FLUSH_MASK) == 0) {
 478                 if (hammer2_debug & 0x200) {
 479                         if (info->debug == NULL)
 480                                 info->debug = chain;
 481                 } else {
 482                         return;
 483                 }
 484         }
 485
 486         hmp = chain->hmp;
 487         diddeferral = info->diddeferral;
 488         parent = info->parent;          /* can be NULL */
 489
 490         /*
 491          * Downward search recursion
 492          */
 493         if (chain->flags & (HAMMER2_CHAIN_DEFERRED | HAMMER2_CHAIN_DELAYED)) {
 494                 /*
 495                  * Already deferred.
 496                  */
 497                 ++info->diddeferral;
 498         } else if ((chain->flags & HAMMER2_CHAIN_PFSBOUNDARY) &&
 499                    (flags & HAMMER2_FLUSH_ALL) == 0 &&
 500                    (flags & HAMMER2_FLUSH_TOP) == 0) {
 501                 /*
 502                  * We do not recurse through PFSROOTs.  PFSROOT flushes are
 503                  * handled by the related pmp's (whether mounted or not,
 504                  * including during recovery).
 505                  *
 506                  * But we must still process the PFSROOT chains for block
 507                  * table updates in their parent (which IS part of our flush).
 508                  *
 509                  * Note that the volume root, vchain, does not set this flag.
 510                  * Note the logic here requires that this test be done before
 511                  * the depth-limit test, else it might become the top on a
 512                  * flushq iteration.
 513                  */
 514                 ;
 515         } else if (info->depth == HAMMER2_FLUSH_DEPTH_LIMIT) {
 516                 /*
 517                  * Recursion depth reached.
 518                  */
 519                 KKASSERT((chain->flags & HAMMER2_CHAIN_DELAYED) == 0);
 520                 hammer2_chain_ref(chain);
 521                 TAILQ_INSERT_TAIL(&info->flushq, chain, flush_node);
 522                 atomic_set_int(&chain->flags, HAMMER2_CHAIN_DEFERRED);
 523                 ++info->diddeferral;
 524         } else if (chain->flags & (HAMMER2_CHAIN_ONFLUSH |
 525                                    HAMMER2_CHAIN_DESTROY)) {
 526                 /*
 527                  * Downward recursion search (actual flush occurs bottom-up).
 528                  * pre-clear ONFLUSH.  It can get set again due to races,
 529                  * which we want so the scan finds us again in the next flush.
 530                  *
 531                  * We must also recurse if DESTROY is set so we can finally
 532                  * get rid of the related children, otherwise the node will
 533                  * just get re-flushed on lastdrop.
 534                  */
 535                 atomic_clear_int(&chain->flags, HAMMER2_CHAIN_ONFLUSH);
 536                 info->parent = chain;
 537                 hammer2_spin_ex(&chain->core.spin);
 538                 RB_SCAN(hammer2_chain_tree, &chain->core.rbtree,
 539                         NULL, hammer2_flush_recurse, info);
 540                 hammer2_spin_unex(&chain->core.spin);
 541                 info->parent = parent;
 542                 if (info->diddeferral)
 543                         hammer2_chain_setflush(chain);
 544         }
 545
 546         /*
 547          * Now we are in the bottom-up part of the recursion.
 548          *
 549          * Do not update chain if lower layers were deferred.
 550          */
 551         if (info->diddeferral)
 552                 goto done;
 553
 554         /*
 555          * Propagate the DESTROY flag downwards.  This dummies up the flush
 556          * code and tries to invalidate related buffer cache buffers to
 557          * avoid the disk write.
 558          */
 559         if (parent && (parent->flags & HAMMER2_CHAIN_DESTROY))
 560                 atomic_set_int(&chain->flags, HAMMER2_CHAIN_DESTROY);
 561
 562         /*
 563          * Chain was already modified or has become modified, flush it out.
 564          */
 565 again:
 566         if ((hammer2_debug & 0x200) &&
 567             info->debug &&
 568             (chain->flags & (HAMMER2_CHAIN_MODIFIED | HAMMER2_CHAIN_UPDATE))) {
 569                 hammer2_chain_t *scan = chain;
 570
 571                 kprintf("DISCONNECTED FLUSH %p->%p\n", info->debug, chain);
 572                 while (scan) {
 573                         kprintf("    chain %p [%08x] bref=%016jx:%02x\n",
 574                                 scan, scan->flags,
 575                                 scan->bref.key, scan->bref.type);
 576                         if (scan == info->debug)
 577                                 break;
 578                         scan = scan->parent;
 579                 }
 580         }
 581
 582         if (chain->flags & HAMMER2_CHAIN_MODIFIED) {
 583                 /*
 584                  * Dispose of the modified bit.
 585                  *
 586                  * If parent is present, the UPDATE bit should already be set.
 587                  * UPDATE should already be set.
 588                  * bref.mirror_tid should already be set.
 589                  */
 590                 KKASSERT((chain->flags & HAMMER2_CHAIN_UPDATE) ||
 591                          chain->parent == NULL);
 592                 if (hammer2_debug & 0x800000) {
 593                         hammer2_chain_t *pp;
 594
 595                         for (pp = chain; pp->parent; pp = pp->parent)
 596                                 ;
 597                         kprintf("FLUSH CHAIN %p (p=%p pp=%p/%d) TYPE %d FLAGS %08x (%s)\n",
 598                                 chain, chain->parent, pp, pp->bref.type,
 599                                 chain->bref.type, chain->flags,
 600                                 (chain->bref.type == 1 ? (const char *)chain->data->ipdata.filename : "?")
 601
 602                                 );
 603                         print_backtrace(10);
 604                 }
 605                 atomic_clear_int(&chain->flags, HAMMER2_CHAIN_MODIFIED);
 606                 atomic_add_long(&hammer2_count_modified_chains, -1);
 607
 608                 /*
 609                  * Manage threads waiting for excessive dirty memory to
 610                  * be retired.
 611                  */
 612                 if (chain->pmp)
 613                         hammer2_pfs_memory_wakeup(chain->pmp);
 614
 615 #if 0
 616                 if ((chain->flags & HAMMER2_CHAIN_UPDATE) == 0 &&
 617                     chain != &hmp->vchain &&
 618                     chain != &hmp->fchain) {
 619                         /*
 620                          * Set UPDATE bit indicating that the parent block
 621                          * table requires updating.
 622                          */
 623                         atomic_set_int(&chain->flags, HAMMER2_CHAIN_UPDATE);
 624                 }
 625 #endif
 626
 627                 /*
 628                  * Issue the flush.  This is indirect via the DIO.
 629                  *
 630                  * NOTE: A DELETED node that reaches this point must be
 631                  *       flushed for synchronization point consistency.
 632                  *
 633                  * NOTE: Even though MODIFIED was already set, the related DIO
 634                  *       might not be dirty due to a system buffer cache
 635                  *       flush and must be set dirty if we are going to make
 636                  *       further modifications to the buffer.  Chains with
 637                  *       embedded data don't need this.
 638                  */
 639                 if (hammer2_debug & 0x1000) {
 640                         kprintf("Flush %p.%d %016jx/%d data=%016jx\n",
 641                                 chain, chain->bref.type,
 642                                 (uintmax_t)chain->bref.key,
 643                                 chain->bref.keybits,
 644                                 (uintmax_t)chain->bref.data_off);
 645                 }
 646                 if (hammer2_debug & 0x2000) {
 647                         Debugger("Flush hell");
 648                 }
 649
 650                 /*
 651                  * Update chain CRCs for flush.
 652                  *
 653                  * NOTE: Volume headers are NOT flushed here as they require
 654                  *       special processing.
 655                  */
 656                 switch(chain->bref.type) {
 657                 case HAMMER2_BREF_TYPE_FREEMAP:
 658                         /*
 659                          * Update the volume header's freemap_tid to the
 660                          * freemap's flushing mirror_tid.
 661                          *
 662                          * (note: embedded data, do not call setdirty)
 663                          */
 664                         KKASSERT(hmp->vchain.flags & HAMMER2_CHAIN_MODIFIED);
 665                         KKASSERT(chain == &hmp->fchain);
 666                         hmp->voldata.freemap_tid = chain->bref.mirror_tid;
 667                         if (hammer2_debug & 0x8000) {
 668                                 /* debug only, avoid syslogd loop */
 669                                 kprintf("sync freemap mirror_tid %08jx\n",
 670                                         (intmax_t)chain->bref.mirror_tid);
 671                         }
 672
 673                         /*
 674                          * The freemap can be flushed independently of the
 675                          * main topology, but for the case where it is
 676                          * flushed in the same transaction, and flushed
 677                          * before vchain (a case we want to allow for
 678                          * performance reasons), make sure modifications
 679                          * made during the flush under vchain use a new
 680                          * transaction id.
 681                          *
 682                          * Otherwise the mount recovery code will get confused.
 683                          */
 684                         ++hmp->voldata.mirror_tid;
 685                         break;
 686                 case HAMMER2_BREF_TYPE_VOLUME:
 687                         /*
 688                          * The free block table is flushed by
 689                          * hammer2_vfs_sync() before it flushes vchain.
 690                          * We must still hold fchain locked while copying
 691                          * voldata to volsync, however.
 692                          *
 693                          * (note: embedded data, do not call setdirty)
 694                          */
 695                         hammer2_chain_lock(&hmp->fchain,
 696                                            HAMMER2_RESOLVE_ALWAYS);
 697                         hammer2_voldata_lock(hmp);
 698                         if (hammer2_debug & 0x8000) {
 699                                 /* debug only, avoid syslogd loop */
 700                                 kprintf("sync volume  mirror_tid %08jx\n",
 701                                         (intmax_t)chain->bref.mirror_tid);
 702                         }
 703
 704                         /*
 705                          * Update the volume header's mirror_tid to the
 706                          * main topology's flushing mirror_tid.  It is
 707                          * possible that voldata.mirror_tid is already
 708                          * beyond bref.mirror_tid due to the bump we made
 709                          * above in BREF_TYPE_FREEMAP.
 710                          */
 711                         if (hmp->voldata.mirror_tid < chain->bref.mirror_tid) {
 712                                 hmp->voldata.mirror_tid =
 713                                         chain->bref.mirror_tid;
 714                         }
 715
 716                         /*
 717                          * The volume header is flushed manually by the
 718                          * syncer, not here.  All we do here is adjust the
 719                          * crc's.
 720                          */
 721                         KKASSERT(chain->data != NULL);
 722                         KKASSERT(chain->dio == NULL);
 723
 724                         hmp->voldata.icrc_sects[HAMMER2_VOL_ICRC_SECT1]=
 725                                 hammer2_icrc32(
 726                                         (char *)&hmp->voldata +
 727                                          HAMMER2_VOLUME_ICRC1_OFF,
 728                                         HAMMER2_VOLUME_ICRC1_SIZE);
 729                         hmp->voldata.icrc_sects[HAMMER2_VOL_ICRC_SECT0]=
 730                                 hammer2_icrc32(
 731                                         (char *)&hmp->voldata +
 732                                          HAMMER2_VOLUME_ICRC0_OFF,
 733                                         HAMMER2_VOLUME_ICRC0_SIZE);
 734                         hmp->voldata.icrc_volheader =
 735                                 hammer2_icrc32(
 736                                         (char *)&hmp->voldata +
 737                                          HAMMER2_VOLUME_ICRCVH_OFF,
 738                                         HAMMER2_VOLUME_ICRCVH_SIZE);
 739
 740                         if (hammer2_debug & 0x8000) {
 741                                 /* debug only, avoid syslogd loop */
 742                                 kprintf("syncvolhdr %016jx %016jx\n",
 743                                         hmp->voldata.mirror_tid,
 744                                         hmp->vchain.bref.mirror_tid);
 745                         }
 746                         hmp->volsync = hmp->voldata;
 747                         atomic_set_int(&chain->flags, HAMMER2_CHAIN_VOLUMESYNC);
 748                         hammer2_voldata_unlock(hmp);
 749                         hammer2_chain_unlock(&hmp->fchain);
 750                         break;
 751                 case HAMMER2_BREF_TYPE_DATA:
 752                         /*
 753                          * Data elements have already been flushed via the
 754                          * logical file buffer cache.  Their hash was set in
 755                          * the bref by the vop_write code.  Do not re-dirty.
 756                          *
 757                          * Make sure any device buffer(s) have been flushed
 758                          * out here (there aren't usually any to flush) XXX.
 759                          */
 760                         break;
 761                 case HAMMER2_BREF_TYPE_INDIRECT:
 762                 case HAMMER2_BREF_TYPE_FREEMAP_NODE:
 763                 case HAMMER2_BREF_TYPE_FREEMAP_LEAF:
 764                         /*
 765                          * Buffer I/O will be cleaned up when the volume is
 766                          * flushed (but the kernel is free to flush it before
 767                          * then, as well).
 768                          */
 769                         KKASSERT((chain->flags & HAMMER2_CHAIN_EMBEDDED) == 0);
 770                         hammer2_chain_setcheck(chain, chain->data);
 771                         break;
 772                 case HAMMER2_BREF_TYPE_INODE:
 773                         /*
 774                          * NOTE: We must call io_setdirty() to make any late
 775                          *       changes to the inode data, the system might
 776                          *       have already flushed the buffer.
 777                          */
 778                         if (chain->data->ipdata.meta.op_flags &
 779                             HAMMER2_OPFLAG_PFSROOT) {
 780                                 /*
 781                                  * non-NULL pmp if mounted as a PFS.  We must
 782                                  * sync fields cached in the pmp? XXX
 783                                  */
 784                                 hammer2_inode_data_t *ipdata;
 785
 786                                 hammer2_io_setdirty(chain->dio);
 787                                 ipdata = &chain->data->ipdata;
 788                                 if (chain->pmp) {
 789                                         ipdata->meta.pfs_inum =
 790                                                 chain->pmp->inode_tid;
 791                                 }
 792                         } else {
 793                                 /* can't be mounted as a PFS */
 794                         }
 795
 796                         KKASSERT((chain->flags & HAMMER2_CHAIN_EMBEDDED) == 0);
 797                         hammer2_chain_setcheck(chain, chain->data);
 798                         break;
 799                 default:
 800                         KKASSERT(chain->flags & HAMMER2_CHAIN_EMBEDDED);
 801                         panic("hammer2_flush_core: unsupported "
 802                               "embedded bref %d",
 803                               chain->bref.type);
 804                         /* NOT REACHED */
 805                 }
 806
 807                 /*
 808                  * If the chain was destroyed try to avoid unnecessary I/O.
 809                  * The DIO system buffer may silently disallow the
 810                  * invalidation.
 811                  */
 812                 if (chain->flags & HAMMER2_CHAIN_DESTROY) {
 813                         hammer2_io_t *dio;
 814
 815                         if (chain->dio) {
 816                                 hammer2_io_setinval(chain->dio,
 817                                                     chain->bref.data_off,
 818                                                     chain->bytes);
 819                         } else if ((dio = hammer2_io_getquick(hmp,
 820                                                   chain->bref.data_off,
 821                                                   chain->bytes)) != NULL) {
 822                                 hammer2_io_setinval(dio,
 823                                                     chain->bref.data_off,
 824                                                     chain->bytes);
 825                                 hammer2_io_putblk(&dio);
 826                         }
 827                 }
 828         }
 829
 830         /*
 831          * If UPDATE is set the parent block table may need to be updated.
 832          *
 833          * NOTE: UPDATE may be set on vchain or fchain in which case
 834          *       parent could be NULL.  It's easiest to allow the case
 835          *       and test for NULL.  parent can also wind up being NULL
 836          *       due to a deletion so we need to handle the case anyway.
 837          *
 838          * If no parent exists we can just clear the UPDATE bit.  If the
 839          * chain gets reattached later on the bit will simply get set
 840          * again.
 841          */
 842         if ((chain->flags & HAMMER2_CHAIN_UPDATE) && parent == NULL)
 843                 atomic_clear_int(&chain->flags, HAMMER2_CHAIN_UPDATE);
 844
 845         /*
 846          * The chain may need its blockrefs updated in the parent.  This
 847          * requires some fancy footwork.
 848          */
 849         if (chain->flags & HAMMER2_CHAIN_UPDATE) {
 850                 hammer2_blockref_t *base;
 851                 int count;
 852
 853                 /*
 854                  * Both parent and chain must be locked.  This requires
 855                  * temporarily unlocking the chain.  We have to deal with
 856                  * the case where the chain might be reparented or modified
 857                  * while it was unlocked.
 858                  */
 859                 hammer2_chain_unlock(chain);
 860                 hammer2_chain_lock(parent, HAMMER2_RESOLVE_ALWAYS);
 861                 hammer2_chain_lock(chain, HAMMER2_RESOLVE_MAYBE);
 862                 if (chain->parent != parent) {
 863                         kprintf("PARENT MISMATCH ch=%p p=%p/%p\n",
 864                                 chain, chain->parent, parent);
 865                         hammer2_chain_unlock(parent);
 866                         goto done;
 867                 }
 868
 869                 /*
 870                  * Check race condition.  If someone got in and modified
 871                  * it again while it was unlocked, we have to loop up.
 872                  */
 873                 if (chain->flags & HAMMER2_CHAIN_MODIFIED) {
 874                         hammer2_chain_unlock(parent);
 875                         kprintf("hammer2_flush: chain %p flush-mod race\n",
 876                                 chain);
 877                         goto again;
 878                 }
 879
 880                 /*
 881                  * Clear UPDATE flag, mark parent modified, update its
 882                  * modify_tid if necessary, and adjust the parent blockmap.
 883                  */
 884                 if (chain->flags & HAMMER2_CHAIN_UPDATE)
 885                         atomic_clear_int(&chain->flags, HAMMER2_CHAIN_UPDATE);
 886
 887                 /*
 888                  * (optional code)
 889                  *
 890                  * Avoid actually modifying and updating the parent if it
 891                  * was flagged for destruction.  This can greatly reduce
 892                  * disk I/O in large tree removals because the
 893                  * hammer2_io_setinval() call in the upward recursion
 894                  * (see MODIFIED code above) can only handle a few cases.
 895                  */
 896                 if (parent->flags & HAMMER2_CHAIN_DESTROY) {
 897                         if (parent->bref.modify_tid < chain->bref.modify_tid) {
 898                                 parent->bref.modify_tid =
 899                                         chain->bref.modify_tid;
 900                         }
 901                         atomic_clear_int(&chain->flags, HAMMER2_CHAIN_BMAPPED |
 902                                                         HAMMER2_CHAIN_BMAPUPD);
 903                         hammer2_chain_unlock(parent);
 904                         goto skipupdate;
 905                 }
 906
 907                 /*
 908                  * (semi-optional code)
 909                  *
 910                  * The flusher is responsible for deleting empty indirect
 911                  * blocks at this point.  If we don't do this, no major harm
 912                  * will be done but the empty indirect blocks will stay in
 913                  * the topology and make it a bit messy.
 914                  */
 915                 if (chain->bref.type == HAMMER2_BREF_TYPE_INDIRECT &&
 916                     chain->core.live_count == 0 &&
 917                     (chain->flags & (HAMMER2_CHAIN_INITIAL |
 918                                      HAMMER2_CHAIN_COUNTEDBREFS)) == 0) {
 919                         base = &chain->data->npdata[0];
 920                         count = chain->bytes / sizeof(hammer2_blockref_t);
 921                         hammer2_chain_countbrefs(chain, base, count);
 922                 }
 923                 if (chain->bref.type == HAMMER2_BREF_TYPE_INDIRECT &&
 924                     chain->core.live_count == 0) {
 925 #if 0
 926                         kprintf("DELETE CHAIN %016jx.%02x %016jx/%d refs=%d\n",
 927                                 chain->bref.data_off, chain->bref.type,
 928                                 chain->bref.key, chain->bref.keybits,
 929                                 chain->refs);
 930 #endif
 931                         hammer2_chain_delete(parent, chain,
 932                                              chain->bref.modify_tid,
 933                                              HAMMER2_DELETE_PERMANENT);
 934                         hammer2_chain_unlock(parent);
 935                         goto skipupdate;
 936                 }
 937
 938                 /*
 939                  * We are updating the parent's blockmap, the parent must
 940                  * be set modified.
 941                  */
 942                 hammer2_chain_modify(parent, 0, 0, 0);
 943                 if (parent->bref.modify_tid < chain->bref.modify_tid)
 944                         parent->bref.modify_tid = chain->bref.modify_tid;
 945
 946                 /*
 947                  * Calculate blockmap pointer
 948                  */
 949                 switch(parent->bref.type) {
 950                 case HAMMER2_BREF_TYPE_INODE:
 951                         /*
 952                          * Access the inode's block array.  However, there is
 953                          * no block array if the inode is flagged DIRECTDATA.
 954                          */
 955                         if (parent->data &&
 956                             (parent->data->ipdata.meta.op_flags &
 957                              HAMMER2_OPFLAG_DIRECTDATA) == 0) {
 958                                 base = &parent->data->
 959                                         ipdata.u.blockset.blockref[0];
 960                         } else {
 961                                 base = NULL;
 962                         }
 963                         count = HAMMER2_SET_COUNT;
 964                         break;
 965                 case HAMMER2_BREF_TYPE_INDIRECT:
 966                 case HAMMER2_BREF_TYPE_FREEMAP_NODE:
 967                         if (parent->data)
 968                                 base = &parent->data->npdata[0];
 969                         else
 970                                 base = NULL;
 971                         count = parent->bytes / sizeof(hammer2_blockref_t);
 972                         break;
 973                 case HAMMER2_BREF_TYPE_VOLUME:
 974                         base = &chain->hmp->voldata.sroot_blockset.blockref[0];
 975                         count = HAMMER2_SET_COUNT;
 976                         break;
 977                 case HAMMER2_BREF_TYPE_FREEMAP:
 978                         base = &parent->data->npdata[0];
 979                         count = HAMMER2_SET_COUNT;
 980                         break;
 981                 default:
 982                         base = NULL;
 983                         count = 0;
 984                         panic("hammer2_flush_core: "
 985                               "unrecognized blockref type: %d",
 986                               parent->bref.type);
 987                 }
 988
 989                 /*
 990                  * Blocktable updates
 991                  *
 992                  * We synchronize pending statistics at this time.  Delta
 993                  * adjustments designated for the current and upper level
 994                  * are synchronized.
 995                  */
 996                 if (base && (chain->flags & HAMMER2_CHAIN_BMAPUPD)) {
 997                         if (chain->flags & HAMMER2_CHAIN_BMAPPED) {
 998                                 hammer2_spin_ex(&parent->core.spin);
 999                                 hammer2_base_delete(parent, base, count,
1000                                                     &info->cache_index, chain);
1001                                 hammer2_spin_unex(&parent->core.spin);
1002                                 /* base_delete clears both bits */
1003                         } else {
1004                                 atomic_clear_int(&chain->flags,
1005                                                  HAMMER2_CHAIN_BMAPUPD);
1006                         }
1007                 }
1008                 if (base && (chain->flags & HAMMER2_CHAIN_BMAPPED) == 0) {
1009                         hammer2_spin_ex(&parent->core.spin);
1010                         hammer2_base_insert(parent, base, count,
1011                                             &info->cache_index, chain);
1012                         hammer2_spin_unex(&parent->core.spin);
1013                         /* base_insert sets BMAPPED */
1014                 }
1015                 hammer2_chain_unlock(parent);
1016         }
1017 skipupdate:
1018         ;
1019
1020         /*
1021          * Final cleanup after flush
1022          */
1023 done:
1024         KKASSERT(chain->refs > 0);
1025         if (hammer2_debug & 0x200) {
1026                 if (info->debug == chain)
1027                         info->debug = NULL;
1028         }
1029 }
1030
1031 /*
1032  * Flush recursion helper, called from flush_core, calls flush_core.
1033  *
1034  * Flushes the children of the caller's chain (info->parent), restricted
1035  * by sync_tid.  Set info->domodify if the child's blockref must propagate
1036  * back up to the parent.
1037  *
1038  * Ripouts can move child from rbtree to dbtree or dbq but the caller's
1039  * flush scan order prevents any chains from being lost.  A child can be
1040  * executes more than once.
1041  *
1042  * WARNING! If we do not call hammer2_flush_core() we must update
1043  *          bref.mirror_tid ourselves to indicate that the flush has
1044  *          processed the child.
1045  *
1046  * WARNING! parent->core spinlock is held on entry and return.
1047  */
1048 static int
1049 hammer2_flush_recurse(hammer2_chain_t *child, void *data)
1050 {
1051         hammer2_flush_info_t *info = data;
1052         hammer2_chain_t *parent = info->parent;
1053
1054         /*
1055          * (child can never be fchain or vchain so a special check isn't
1056          *  needed).
1057          *
1058          * We must ref the child before unlocking the spinlock.
1059          *
1060          * The caller has added a ref to the parent so we can temporarily
1061          * unlock it in order to lock the child.
1062          */
1063         hammer2_chain_ref(child);
1064         hammer2_spin_unex(&parent->core.spin);
1065
1066         hammer2_chain_unlock(parent);
1067         hammer2_chain_lock(child, HAMMER2_RESOLVE_MAYBE);
1068
1069         /*
1070          * Must propagate the DESTROY flag downwards, otherwise the
1071          * parent could end up never being removed because it will
1072          * be requeued to the flusher if it survives this run due to
1073          * the flag.
1074          */
1075         if (parent && (parent->flags & HAMMER2_CHAIN_DESTROY))
1076                 atomic_set_int(&child->flags, HAMMER2_CHAIN_DESTROY);
1077
1078         /*
1079          * Recurse and collect deferral data.  We're in the media flush,
1080          * this can cross PFS boundaries.
1081          */
1082         if (child->flags & HAMMER2_CHAIN_FLUSH_MASK) {
1083                 ++info->depth;
1084                 hammer2_flush_core(info, child, info->flags);
1085                 --info->depth;
1086         } else if (hammer2_debug & 0x200) {
1087                 if (info->debug == NULL)
1088                         info->debug = child;
1089                 ++info->depth;
1090                 hammer2_flush_core(info, child, info->flags);
1091                 --info->depth;
1092                 if (info->debug == child)
1093                         info->debug = NULL;
1094         }
1095
1096         /*
1097          * Relock to continue the loop
1098          */
1099         hammer2_chain_unlock(child);
1100         hammer2_chain_lock(parent, HAMMER2_RESOLVE_MAYBE);
1101         hammer2_chain_drop(child);
1102         KKASSERT(info->parent == parent);
1103         hammer2_spin_ex(&parent->core.spin);
1104
1105         return (0);
1106 }
1107
1108 /*
1109  * flush helper (direct)
1110  *
1111  * Quickly flushes any dirty chains for a device.  This will update our
1112  * concept of the volume root but does NOT flush the actual volume root
1113  * and does not flush dirty device buffers.
1114  *
1115  * This function is primarily used by the bulkfree code to allow it to
1116  * create a snapshot for the pass.  It doesn't care about any pending
1117  * work (dirty vnodes, dirty inodes, dirty logical buffers) for which blocks
1118  * have not yet been allocated.
1119  */
1120 void
1121 hammer2_flush_quick(hammer2_dev_t *hmp)
1122 {
1123         hammer2_chain_t *chain;
1124
1125         hammer2_trans_init(hmp->spmp, HAMMER2_TRANS_ISFLUSH);
1126
1127         hammer2_chain_ref(&hmp->vchain);
1128         hammer2_chain_lock(&hmp->vchain, HAMMER2_RESOLVE_ALWAYS);
1129         if (hmp->vchain.flags & HAMMER2_CHAIN_FLUSH_MASK) {
1130                 chain = &hmp->vchain;
1131                 hammer2_flush(chain, HAMMER2_FLUSH_TOP |
1132                                      HAMMER2_FLUSH_ALL);
1133                 KKASSERT(chain == &hmp->vchain);
1134         }
1135         hammer2_chain_unlock(&hmp->vchain);
1136         hammer2_chain_drop(&hmp->vchain);
1137
1138         hammer2_trans_done(hmp->spmp);  /* spmp trans */
1139 }
1140
1141 /*
1142  * flush helper (backend threaded)
1143  *
1144  * Flushes core chains, issues disk sync, flushes volume roots.
1145  *
1146  * Primarily called from vfs_sync().
1147  */
1148 void
1149 hammer2_inode_xop_flush(hammer2_xop_t *arg, int clindex)
1150 {
1151         hammer2_xop_flush_t *xop = &arg->xop_flush;
1152         hammer2_chain_t *chain;
1153         hammer2_chain_t *parent;
1154         hammer2_dev_t *hmp;
1155         int error = 0;
1156         int total_error = 0;
1157         int j;
1158
1159         /*
1160          * Flush core chains
1161          */
1162         chain = hammer2_inode_chain(xop->head.ip1, clindex,
1163                                     HAMMER2_RESOLVE_ALWAYS);
1164         if (chain) {
1165                 hmp = chain->hmp;
1166                 if ((chain->flags & HAMMER2_CHAIN_FLUSH_MASK) ||
1167                     TAILQ_FIRST(&hmp->flushq) != NULL) {
1168                         hammer2_flush(chain, HAMMER2_FLUSH_TOP);
1169                         parent = chain->parent;
1170                         KKASSERT(chain->pmp != parent->pmp);
1171                         hammer2_chain_setflush(parent);
1172                 }
1173                 hammer2_chain_unlock(chain);
1174                 hammer2_chain_drop(chain);
1175                 chain = NULL;
1176         } else {
1177                 hmp = NULL;
1178         }
1179
1180         /*
1181          * Flush volume roots.  Avoid replication, we only want to
1182          * flush each hammer2_dev (hmp) once.
1183          */
1184         for (j = clindex - 1; j >= 0; --j) {
1185                 if ((chain = xop->head.ip1->cluster.array[j].chain) != NULL) {
1186                         if (chain->hmp == hmp) {
1187                                 chain = NULL;   /* safety */
1188                                 goto skip;
1189                         }
1190                 }
1191         }
1192         chain = NULL;   /* safety */
1193
1194         /*
1195          * spmp transaction.  The super-root is never directly mounted so
1196          * there shouldn't be any vnodes, let alone any dirty vnodes
1197          * associated with it, so we shouldn't have to mess around with any
1198          * vnode flushes here.
1199          */
1200         hammer2_trans_init(hmp->spmp, HAMMER2_TRANS_ISFLUSH);
1201
1202         /*
1203          * Media mounts have two 'roots', vchain for the topology
1204          * and fchain for the free block table.  Flush both.
1205          *
1206          * Note that the topology and free block table are handled
1207          * independently, so the free block table can wind up being
1208          * ahead of the topology.  We depend on the bulk free scan
1209          * code to deal with any loose ends.
1210          */
1211         hammer2_chain_ref(&hmp->vchain);
1212         hammer2_chain_lock(&hmp->vchain, HAMMER2_RESOLVE_ALWAYS);
1213         hammer2_chain_ref(&hmp->fchain);
1214         hammer2_chain_lock(&hmp->fchain, HAMMER2_RESOLVE_ALWAYS);
1215         if (hmp->fchain.flags & HAMMER2_CHAIN_FLUSH_MASK) {
1216                 /*
1217                  * This will also modify vchain as a side effect,
1218                  * mark vchain as modified now.
1219                  */
1220                 hammer2_voldata_modify(hmp);
1221                 chain = &hmp->fchain;
1222                 hammer2_flush(chain, HAMMER2_FLUSH_TOP);
1223                 KKASSERT(chain == &hmp->fchain);
1224         }
1225         hammer2_chain_unlock(&hmp->fchain);
1226         hammer2_chain_unlock(&hmp->vchain);
1227         hammer2_chain_drop(&hmp->fchain);
1228         /* vchain dropped down below */
1229
1230         hammer2_chain_lock(&hmp->vchain, HAMMER2_RESOLVE_ALWAYS);
1231         if (hmp->vchain.flags & HAMMER2_CHAIN_FLUSH_MASK) {
1232                 chain = &hmp->vchain;
1233                 hammer2_flush(chain, HAMMER2_FLUSH_TOP);
1234                 KKASSERT(chain == &hmp->vchain);
1235         }
1236         hammer2_chain_unlock(&hmp->vchain);
1237         hammer2_chain_drop(&hmp->vchain);
1238
1239         error = 0;
1240
1241         /*
1242          * We can't safely flush the volume header until we have
1243          * flushed any device buffers which have built up.
1244          *
1245          * XXX this isn't being incremental
1246          */
1247         vn_lock(hmp->devvp, LK_EXCLUSIVE | LK_RETRY);
1248         error = VOP_FSYNC(hmp->devvp, MNT_WAIT, 0);
1249         vn_unlock(hmp->devvp);
1250
1251         /*
1252          * The flush code sets CHAIN_VOLUMESYNC to indicate that the
1253          * volume header needs synchronization via hmp->volsync.
1254          *
1255          * XXX synchronize the flag & data with only this flush XXX
1256          */
1257         if (error == 0 &&
1258             (hmp->vchain.flags & HAMMER2_CHAIN_VOLUMESYNC)) {
1259                 struct buf *bp;
1260
1261                 /*
1262                  * Synchronize the disk before flushing the volume
1263                  * header.
1264                  */
1265                 bp = getpbuf(NULL);
1266                 bp->b_bio1.bio_offset = 0;
1267                 bp->b_bufsize = 0;
1268                 bp->b_bcount = 0;
1269                 bp->b_cmd = BUF_CMD_FLUSH;
1270                 bp->b_bio1.bio_done = biodone_sync;
1271                 bp->b_bio1.bio_flags |= BIO_SYNC;
1272                 vn_strategy(hmp->devvp, &bp->b_bio1);
1273                 biowait(&bp->b_bio1, "h2vol");
1274                 relpbuf(bp, NULL);
1275
1276                 /*
1277                  * Then we can safely flush the version of the
1278                  * volume header synchronized by the flush code.
1279                  */
1280                 j = hmp->volhdrno + 1;
1281                 if (j >= HAMMER2_NUM_VOLHDRS)
1282                         j = 0;
1283                 if (j * HAMMER2_ZONE_BYTES64 + HAMMER2_SEGSIZE >
1284                     hmp->volsync.volu_size) {
1285                         j = 0;
1286                 }
1287                 if (hammer2_debug & 0x8000) {
1288                         /* debug only, avoid syslogd loop */
1289                         kprintf("sync volhdr %d %jd\n",
1290                                 j, (intmax_t)hmp->volsync.volu_size);
1291                 }
1292                 bp = getblk(hmp->devvp, j * HAMMER2_ZONE_BYTES64,
1293                             HAMMER2_PBUFSIZE, 0, 0);
1294                 atomic_clear_int(&hmp->vchain.flags,
1295                                  HAMMER2_CHAIN_VOLUMESYNC);
1296                 bcopy(&hmp->volsync, bp->b_data, HAMMER2_PBUFSIZE);
1297                 bawrite(bp);
1298                 hmp->volhdrno = j;
1299         }
1300         if (error)
1301                 total_error = error;
1302
1303         hammer2_trans_done(hmp->spmp);  /* spmp trans */
1304 skip:
1305         error = hammer2_xop_feed(&xop->head, NULL, clindex, total_error);
1306 }