The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/vfs/hammer/hammer_ondisk.c

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    1 /*
    2  * Copyright (c) 2007-2008 The DragonFly Project.  All rights reserved.
    3  * 
    4  * This code is derived from software contributed to The DragonFly Project
    5  * by Matthew Dillon <dillon@backplane.com>
    6  * 
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   10  * 
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, this list of conditions and the following disclaimer.
   13  * 2. Redistributions in binary form must reproduce the above copyright
   14  *    notice, this list of conditions and the following disclaimer in
   15  *    the documentation and/or other materials provided with the
   16  *    distribution.
   17  * 3. Neither the name of The DragonFly Project nor the names of its
   18  *    contributors may be used to endorse or promote products derived
   19  *    from this software without specific, prior written permission.
   20  * 
   21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
   25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
   27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
   29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   32  * SUCH DAMAGE.
   33  * 
   34  * $DragonFly: src/sys/vfs/hammer/hammer_ondisk.c,v 1.76 2008/08/29 20:19:08 dillon Exp $
   35  */
   36 /*
   37  * Manage HAMMER's on-disk structures.  These routines are primarily
   38  * responsible for interfacing with the kernel's I/O subsystem and for
   39  * managing in-memory structures.
   40  */
   41 
   42 #include "hammer.h"
   43 #include <sys/fcntl.h>
   44 #include <sys/nlookup.h>
   45 #include <sys/buf.h>
   46 
   47 #include <sys/buf2.h>
   48 
   49 static void hammer_free_volume(hammer_volume_t volume);
   50 static int hammer_load_volume(hammer_volume_t volume);
   51 static int hammer_load_buffer(hammer_buffer_t buffer, int isnew);
   52 static int hammer_load_node(hammer_transaction_t trans,
   53                                 hammer_node_t node, int isnew);
   54 static void _hammer_rel_node(hammer_node_t node, int locked);
   55 
   56 static int
   57 hammer_vol_rb_compare(hammer_volume_t vol1, hammer_volume_t vol2)
   58 {
   59         if (vol1->vol_no < vol2->vol_no)
   60                 return(-1);
   61         if (vol1->vol_no > vol2->vol_no)
   62                 return(1);
   63         return(0);
   64 }
   65 
   66 /*
   67  * hammer_buffer structures are indexed via their zoneX_offset, not
   68  * their zone2_offset.
   69  */
   70 static int
   71 hammer_buf_rb_compare(hammer_buffer_t buf1, hammer_buffer_t buf2)
   72 {
   73         if (buf1->zoneX_offset < buf2->zoneX_offset)
   74                 return(-1);
   75         if (buf1->zoneX_offset > buf2->zoneX_offset)
   76                 return(1);
   77         return(0);
   78 }
   79 
   80 static int
   81 hammer_nod_rb_compare(hammer_node_t node1, hammer_node_t node2)
   82 {
   83         if (node1->node_offset < node2->node_offset)
   84                 return(-1);
   85         if (node1->node_offset > node2->node_offset)
   86                 return(1);
   87         return(0);
   88 }
   89 
   90 RB_GENERATE2(hammer_vol_rb_tree, hammer_volume, rb_node,
   91              hammer_vol_rb_compare, int32_t, vol_no);
   92 RB_GENERATE2(hammer_buf_rb_tree, hammer_buffer, rb_node,
   93              hammer_buf_rb_compare, hammer_off_t, zoneX_offset);
   94 RB_GENERATE2(hammer_nod_rb_tree, hammer_node, rb_node,
   95              hammer_nod_rb_compare, hammer_off_t, node_offset);
   96 
   97 /************************************************************************
   98  *                              VOLUMES                                 *
   99  ************************************************************************
  100  *
  101  * Load a HAMMER volume by name.  Returns 0 on success or a positive error
  102  * code on failure.  Volumes must be loaded at mount time, get_volume() will
  103  * not load a new volume.
  104  *
  105  * The passed devvp is vref()'d but not locked.  This function consumes the
  106  * ref (typically by associating it with the volume structure).
  107  *
  108  * Calls made to hammer_load_volume() or single-threaded
  109  */
  110 int
  111 hammer_install_volume(struct hammer_mount *hmp, const char *volname,
  112                       struct vnode *devvp)
  113 {
  114         struct mount *mp;
  115         hammer_volume_t volume;
  116         struct hammer_volume_ondisk *ondisk;
  117         struct nlookupdata nd;
  118         struct buf *bp = NULL;
  119         int error;
  120         int ronly;
  121         int setmp = 0;
  122 
  123         mp = hmp->mp;
  124         ronly = ((mp->mnt_flag & MNT_RDONLY) ? 1 : 0);
  125 
  126         /*
  127          * Allocate a volume structure
  128          */
  129         ++hammer_count_volumes;
  130         volume = kmalloc(sizeof(*volume), hmp->m_misc, M_WAITOK|M_ZERO);
  131         volume->vol_name = kstrdup(volname, hmp->m_misc);
  132         volume->io.hmp = hmp;   /* bootstrap */
  133         hammer_io_init(&volume->io, volume, HAMMER_STRUCTURE_VOLUME);
  134         volume->io.offset = 0LL;
  135         volume->io.bytes = HAMMER_BUFSIZE;
  136 
  137         /*
  138          * Get the device vnode
  139          */
  140         if (devvp == NULL) {
  141                 error = nlookup_init(&nd, volume->vol_name, UIO_SYSSPACE, NLC_FOLLOW);
  142                 if (error == 0)
  143                         error = nlookup(&nd);
  144                 if (error == 0)
  145                         error = cache_vref(&nd.nl_nch, nd.nl_cred, &volume->devvp);
  146                 nlookup_done(&nd);
  147         } else {
  148                 error = 0;
  149                 volume->devvp = devvp;
  150         }
  151 
  152         if (error == 0) {
  153                 if (vn_isdisk(volume->devvp, &error)) {
  154                         error = vfs_mountedon(volume->devvp);
  155                 }
  156         }
  157         if (error == 0 && vcount(volume->devvp) > 0)
  158                 error = EBUSY;
  159         if (error == 0) {
  160                 vn_lock(volume->devvp, LK_EXCLUSIVE | LK_RETRY);
  161                 error = vinvalbuf(volume->devvp, V_SAVE, 0, 0);
  162                 if (error == 0) {
  163                         error = VOP_OPEN(volume->devvp, 
  164                                          (ronly ? FREAD : FREAD|FWRITE),
  165                                          FSCRED, NULL);
  166                 }
  167                 vn_unlock(volume->devvp);
  168         }
  169         if (error) {
  170                 hammer_free_volume(volume);
  171                 return(error);
  172         }
  173         volume->devvp->v_rdev->si_mountpoint = mp;
  174         setmp = 1;
  175 
  176         /*
  177          * Extract the volume number from the volume header and do various
  178          * sanity checks.
  179          */
  180         error = bread(volume->devvp, 0LL, HAMMER_BUFSIZE, &bp);
  181         if (error)
  182                 goto late_failure;
  183         ondisk = (void *)bp->b_data;
  184         if (ondisk->vol_signature != HAMMER_FSBUF_VOLUME) {
  185                 kprintf("hammer_mount: volume %s has an invalid header\n",
  186                         volume->vol_name);
  187                 error = EFTYPE;
  188                 goto late_failure;
  189         }
  190         volume->vol_no = ondisk->vol_no;
  191         volume->buffer_base = ondisk->vol_buf_beg;
  192         volume->vol_flags = ondisk->vol_flags;
  193         volume->nblocks = ondisk->vol_nblocks; 
  194         volume->maxbuf_off = HAMMER_ENCODE_RAW_BUFFER(volume->vol_no,
  195                                     ondisk->vol_buf_end - ondisk->vol_buf_beg);
  196         volume->maxraw_off = ondisk->vol_buf_end;
  197 
  198         if (RB_EMPTY(&hmp->rb_vols_root)) {
  199                 hmp->fsid = ondisk->vol_fsid;
  200         } else if (bcmp(&hmp->fsid, &ondisk->vol_fsid, sizeof(uuid_t))) {
  201                 kprintf("hammer_mount: volume %s's fsid does not match "
  202                         "other volumes\n", volume->vol_name);
  203                 error = EFTYPE;
  204                 goto late_failure;
  205         }
  206 
  207         /*
  208          * Insert the volume structure into the red-black tree.
  209          */
  210         if (RB_INSERT(hammer_vol_rb_tree, &hmp->rb_vols_root, volume)) {
  211                 kprintf("hammer_mount: volume %s has a duplicate vol_no %d\n",
  212                         volume->vol_name, volume->vol_no);
  213                 error = EEXIST;
  214         }
  215 
  216         /*
  217          * Set the root volume .  HAMMER special cases rootvol the structure.
  218          * We do not hold a ref because this would prevent related I/O
  219          * from being flushed.
  220          */
  221         if (error == 0 && ondisk->vol_rootvol == ondisk->vol_no) {
  222                 hmp->rootvol = volume;
  223                 hmp->nvolumes = ondisk->vol_count;
  224                 if (bp) {
  225                         brelse(bp);
  226                         bp = NULL;
  227                 }
  228                 hmp->mp->mnt_stat.f_blocks += ondisk->vol0_stat_bigblocks *
  229                         (HAMMER_LARGEBLOCK_SIZE / HAMMER_BUFSIZE);
  230                 hmp->mp->mnt_vstat.f_blocks += ondisk->vol0_stat_bigblocks *
  231                         (HAMMER_LARGEBLOCK_SIZE / HAMMER_BUFSIZE);
  232         }
  233 late_failure:
  234         if (bp)
  235                 brelse(bp);
  236         if (error) {
  237                 /*vinvalbuf(volume->devvp, V_SAVE, 0, 0);*/
  238                 if (setmp)
  239                         volume->devvp->v_rdev->si_mountpoint = NULL;
  240                 vn_lock(volume->devvp, LK_EXCLUSIVE | LK_RETRY);
  241                 VOP_CLOSE(volume->devvp, ronly ? FREAD : FREAD|FWRITE);
  242                 vn_unlock(volume->devvp);
  243                 hammer_free_volume(volume);
  244         }
  245         return (error);
  246 }
  247 
  248 /*
  249  * This is called for each volume when updating the mount point from
  250  * read-write to read-only or vise-versa.
  251  */
  252 int
  253 hammer_adjust_volume_mode(hammer_volume_t volume, void *data __unused)
  254 {
  255         if (volume->devvp) {
  256                 vn_lock(volume->devvp, LK_EXCLUSIVE | LK_RETRY);
  257                 if (volume->io.hmp->ronly) {
  258                         /* do not call vinvalbuf */
  259                         VOP_OPEN(volume->devvp, FREAD, FSCRED, NULL);
  260                         VOP_CLOSE(volume->devvp, FREAD|FWRITE);
  261                 } else {
  262                         /* do not call vinvalbuf */
  263                         VOP_OPEN(volume->devvp, FREAD|FWRITE, FSCRED, NULL);
  264                         VOP_CLOSE(volume->devvp, FREAD);
  265                 }
  266                 vn_unlock(volume->devvp);
  267         }
  268         return(0);
  269 }
  270 
  271 /*
  272  * Unload and free a HAMMER volume.  Must return >= 0 to continue scan
  273  * so returns -1 on failure.
  274  */
  275 int
  276 hammer_unload_volume(hammer_volume_t volume, void *data __unused)
  277 {
  278         hammer_mount_t hmp = volume->io.hmp;
  279         int ronly = ((hmp->mp->mnt_flag & MNT_RDONLY) ? 1 : 0);
  280 
  281         /*
  282          * Clean up the root volume pointer, which is held unlocked in hmp.
  283          */
  284         if (hmp->rootvol == volume)
  285                 hmp->rootvol = NULL;
  286 
  287         /*
  288          * We must not flush a dirty buffer to disk on umount.  It should
  289          * have already been dealt with by the flusher, or we may be in
  290          * catastrophic failure.
  291          */
  292         hammer_io_clear_modify(&volume->io, 1);
  293         volume->io.waitdep = 1;
  294 
  295         /*
  296          * Clean up the persistent ref ioerror might have on the volume
  297          */
  298         if (volume->io.ioerror)
  299                 hammer_io_clear_error_noassert(&volume->io);
  300 
  301         /*
  302          * This should release the bp.  Releasing the volume with flush set
  303          * implies the interlock is set.
  304          */
  305         hammer_ref_interlock_true(&volume->io.lock);
  306         hammer_rel_volume(volume, 1);
  307         KKASSERT(volume->io.bp == NULL);
  308 
  309         /*
  310          * There should be no references on the volume, no clusters, and
  311          * no super-clusters.
  312          */
  313         KKASSERT(hammer_norefs(&volume->io.lock));
  314 
  315         volume->ondisk = NULL;
  316         if (volume->devvp) {
  317                 if (volume->devvp->v_rdev &&
  318                     volume->devvp->v_rdev->si_mountpoint == hmp->mp
  319                 ) {
  320                         volume->devvp->v_rdev->si_mountpoint = NULL;
  321                 }
  322                 if (ronly) {
  323                         /*
  324                          * Make sure we don't sync anything to disk if we
  325                          * are in read-only mode (1) or critically-errored
  326                          * (2).  Note that there may be dirty buffers in
  327                          * normal read-only mode from crash recovery.
  328                          */
  329                         vn_lock(volume->devvp, LK_EXCLUSIVE | LK_RETRY);
  330                         vinvalbuf(volume->devvp, 0, 0, 0);
  331                         VOP_CLOSE(volume->devvp, FREAD);
  332                         vn_unlock(volume->devvp);
  333                 } else {
  334                         /*
  335                          * Normal termination, save any dirty buffers
  336                          * (XXX there really shouldn't be any).
  337                          */
  338                         vn_lock(volume->devvp, LK_EXCLUSIVE | LK_RETRY);
  339                         vinvalbuf(volume->devvp, V_SAVE, 0, 0);
  340                         VOP_CLOSE(volume->devvp, FREAD|FWRITE);
  341                         vn_unlock(volume->devvp);
  342                 }
  343         }
  344 
  345         /*
  346          * Destroy the structure
  347          */
  348         RB_REMOVE(hammer_vol_rb_tree, &hmp->rb_vols_root, volume);
  349         hammer_free_volume(volume);
  350         return(0);
  351 }
  352 
  353 static
  354 void
  355 hammer_free_volume(hammer_volume_t volume)
  356 {
  357         hammer_mount_t hmp = volume->io.hmp;
  358 
  359         if (volume->vol_name) {
  360                 kfree(volume->vol_name, hmp->m_misc);
  361                 volume->vol_name = NULL;
  362         }
  363         if (volume->devvp) {
  364                 vrele(volume->devvp);
  365                 volume->devvp = NULL;
  366         }
  367         --hammer_count_volumes;
  368         kfree(volume, hmp->m_misc);
  369 }
  370 
  371 /*
  372  * Get a HAMMER volume.  The volume must already exist.
  373  */
  374 hammer_volume_t
  375 hammer_get_volume(struct hammer_mount *hmp, int32_t vol_no, int *errorp)
  376 {
  377         struct hammer_volume *volume;
  378 
  379         /*
  380          * Locate the volume structure
  381          */
  382         volume = RB_LOOKUP(hammer_vol_rb_tree, &hmp->rb_vols_root, vol_no);
  383         if (volume == NULL) {
  384                 *errorp = ENOENT;
  385                 return(NULL);
  386         }
  387 
  388         /*
  389          * Reference the volume, load/check the data on the 0->1 transition.
  390          * hammer_load_volume() will dispose of the interlock on return,
  391          * and also clean up the ref count on error.
  392          */
  393         if (hammer_ref_interlock(&volume->io.lock)) {
  394                 *errorp = hammer_load_volume(volume);
  395                 if (*errorp)
  396                         volume = NULL;
  397         } else {
  398                 KKASSERT(volume->ondisk);
  399                 *errorp = 0;
  400         }
  401         return(volume);
  402 }
  403 
  404 int
  405 hammer_ref_volume(hammer_volume_t volume)
  406 {
  407         int error;
  408 
  409         /*
  410          * Reference the volume and deal with the check condition used to
  411          * load its ondisk info.
  412          */
  413         if (hammer_ref_interlock(&volume->io.lock)) {
  414                 error = hammer_load_volume(volume);
  415         } else {
  416                 KKASSERT(volume->ondisk);
  417                 error = 0;
  418         }
  419         return (error);
  420 }
  421 
  422 /*
  423  * May be called without fs_token
  424  */
  425 hammer_volume_t
  426 hammer_get_root_volume(struct hammer_mount *hmp, int *errorp)
  427 {
  428         hammer_volume_t volume;
  429 
  430         volume = hmp->rootvol;
  431         KKASSERT(volume != NULL);
  432 
  433         /*
  434          * Reference the volume and deal with the check condition used to
  435          * load its ondisk info.
  436          */
  437         if (hammer_ref_interlock(&volume->io.lock)) {
  438                 lwkt_gettoken(&volume->io.hmp->fs_token);
  439                 *errorp = hammer_load_volume(volume);
  440                 lwkt_reltoken(&volume->io.hmp->fs_token);
  441                 if (*errorp)
  442                         volume = NULL;
  443         } else {
  444                 KKASSERT(volume->ondisk);
  445                 *errorp = 0;
  446         }
  447         return (volume);
  448 }
  449 
  450 /*
  451  * Load a volume's on-disk information.  The volume must be referenced and
  452  * the interlock is held on call.  The interlock will be released on return.
  453  * The reference will also be released on return if an error occurs.
  454  */
  455 static int
  456 hammer_load_volume(hammer_volume_t volume)
  457 {
  458         int error;
  459 
  460         if (volume->ondisk == NULL) {
  461                 error = hammer_io_read(volume->devvp, &volume->io,
  462                                        HAMMER_BUFSIZE);
  463                 if (error == 0) {
  464                         volume->ondisk = (void *)volume->io.bp->b_data;
  465                         hammer_ref_interlock_done(&volume->io.lock);
  466                 } else {
  467                         hammer_rel_volume(volume, 1);
  468                 }
  469         } else {
  470                 error = 0;
  471         }
  472         return(error);
  473 }
  474 
  475 /*
  476  * Release a previously acquired reference on the volume.
  477  *
  478  * Volumes are not unloaded from memory during normal operation.
  479  *
  480  * May be called without fs_token
  481  */
  482 void
  483 hammer_rel_volume(hammer_volume_t volume, int locked)
  484 {
  485         struct buf *bp;
  486 
  487         if (hammer_rel_interlock(&volume->io.lock, locked)) {
  488                 lwkt_gettoken(&volume->io.hmp->fs_token);
  489                 volume->ondisk = NULL;
  490                 bp = hammer_io_release(&volume->io, locked);
  491                 lwkt_reltoken(&volume->io.hmp->fs_token);
  492                 hammer_rel_interlock_done(&volume->io.lock, locked);
  493                 if (bp)
  494                         brelse(bp);
  495         }
  496 }
  497 
  498 int
  499 hammer_mountcheck_volumes(struct hammer_mount *hmp)
  500 {
  501         hammer_volume_t vol;
  502         int i;
  503 
  504         for (i = 0; i < hmp->nvolumes; ++i) {
  505                 vol = RB_LOOKUP(hammer_vol_rb_tree, &hmp->rb_vols_root, i);
  506                 if (vol == NULL)
  507                         return(EINVAL);
  508         }
  509         return(0);
  510 }
  511 
  512 /************************************************************************
  513  *                              BUFFERS                                 *
  514  ************************************************************************
  515  *
  516  * Manage buffers.  Currently most blockmap-backed zones are direct-mapped
  517  * to zone-2 buffer offsets, without a translation stage.  However, the
  518  * hammer_buffer structure is indexed by its zoneX_offset, not its
  519  * zone2_offset.
  520  *
  521  * The proper zone must be maintained throughout the code-base all the way
  522  * through to the big-block allocator, or routines like hammer_del_buffers()
  523  * will not be able to locate all potentially conflicting buffers.
  524  */
  525 
  526 /*
  527  * Helper function returns whether a zone offset can be directly translated
  528  * to a raw buffer index or not.  Really only the volume and undo zones
  529  * can't be directly translated.  Volumes are special-cased and undo zones
  530  * shouldn't be aliased accessed in read-only mode.
  531  *
  532  * This function is ONLY used to detect aliased zones during a read-only
  533  * mount.
  534  */
  535 static __inline int
  536 hammer_direct_zone(hammer_off_t buf_offset)
  537 {
  538         switch(HAMMER_ZONE_DECODE(buf_offset)) {
  539         case HAMMER_ZONE_RAW_BUFFER_INDEX:
  540         case HAMMER_ZONE_FREEMAP_INDEX:
  541         case HAMMER_ZONE_BTREE_INDEX:
  542         case HAMMER_ZONE_META_INDEX:
  543         case HAMMER_ZONE_LARGE_DATA_INDEX:
  544         case HAMMER_ZONE_SMALL_DATA_INDEX:
  545                 return(1);
  546         default:
  547                 return(0);
  548         }
  549         /* NOT REACHED */
  550 }
  551 
  552 hammer_buffer_t
  553 hammer_get_buffer(hammer_mount_t hmp, hammer_off_t buf_offset,
  554                   int bytes, int isnew, int *errorp)
  555 {
  556         hammer_buffer_t buffer;
  557         hammer_volume_t volume;
  558         hammer_off_t    zone2_offset;
  559         hammer_io_type_t iotype;
  560         int vol_no;
  561         int zone;
  562 
  563         buf_offset &= ~HAMMER_BUFMASK64;
  564 again:
  565         /*
  566          * Shortcut if the buffer is already cached
  567          */
  568         buffer = RB_LOOKUP(hammer_buf_rb_tree, &hmp->rb_bufs_root, buf_offset);
  569         if (buffer) {
  570                 /*
  571                  * Once refed the ondisk field will not be cleared by
  572                  * any other action.  Shortcut the operation if the
  573                  * ondisk structure is valid.
  574                  */
  575 found_aliased:
  576                 if (hammer_ref_interlock(&buffer->io.lock) == 0) {
  577                         hammer_io_advance(&buffer->io);
  578                         KKASSERT(buffer->ondisk);
  579                         *errorp = 0;
  580                         return(buffer);
  581                 }
  582 
  583                 /*
  584                  * 0->1 transition or defered 0->1 transition (CHECK),
  585                  * interlock now held.  Shortcut if ondisk is already
  586                  * assigned.
  587                  */
  588                 atomic_add_int(&hammer_count_refedbufs, 1);
  589                 if (buffer->ondisk) {
  590                         hammer_io_advance(&buffer->io);
  591                         hammer_ref_interlock_done(&buffer->io.lock);
  592                         *errorp = 0;
  593                         return(buffer);
  594                 }
  595 
  596                 /*
  597                  * The buffer is no longer loose if it has a ref, and
  598                  * cannot become loose once it gains a ref.  Loose
  599                  * buffers will never be in a modified state.  This should
  600                  * only occur on the 0->1 transition of refs.
  601                  *
  602                  * lose_list can be modified via a biodone() interrupt
  603                  * so the io_token must be held.
  604                  */
  605                 if (buffer->io.mod_root == &hmp->lose_root) {
  606                         lwkt_gettoken(&hmp->io_token);
  607                         if (buffer->io.mod_root == &hmp->lose_root) {
  608                                 RB_REMOVE(hammer_mod_rb_tree,
  609                                           buffer->io.mod_root, &buffer->io);
  610                                 buffer->io.mod_root = NULL;
  611                                 KKASSERT(buffer->io.modified == 0);
  612                         }
  613                         lwkt_reltoken(&hmp->io_token);
  614                 }
  615                 goto found;
  616         } else if (hmp->ronly && hammer_direct_zone(buf_offset)) {
  617                 /*
  618                  * If this is a read-only mount there could be an alias
  619                  * in the raw-zone.  If there is we use that buffer instead.
  620                  *
  621                  * rw mounts will not have aliases.  Also note when going
  622                  * from ro -> rw the recovered raw buffers are flushed and
  623                  * reclaimed, so again there will not be any aliases once
  624                  * the mount is rw.
  625                  */
  626                 buffer = RB_LOOKUP(hammer_buf_rb_tree, &hmp->rb_bufs_root,
  627                                    (buf_offset & ~HAMMER_OFF_ZONE_MASK) |
  628                                    HAMMER_ZONE_RAW_BUFFER);
  629                 if (buffer) {
  630                         kprintf("HAMMER: recovered aliased %016jx\n",
  631                                 (intmax_t)buf_offset);
  632                         goto found_aliased;
  633                 }
  634         }
  635 
  636         /*
  637          * What is the buffer class?
  638          */
  639         zone = HAMMER_ZONE_DECODE(buf_offset);
  640 
  641         switch(zone) {
  642         case HAMMER_ZONE_LARGE_DATA_INDEX:
  643         case HAMMER_ZONE_SMALL_DATA_INDEX:
  644                 iotype = HAMMER_STRUCTURE_DATA_BUFFER;
  645                 break;
  646         case HAMMER_ZONE_UNDO_INDEX:
  647                 iotype = HAMMER_STRUCTURE_UNDO_BUFFER;
  648                 break;
  649         case HAMMER_ZONE_META_INDEX:
  650         default:
  651                 /*
  652                  * NOTE: inode data and directory entries are placed in this
  653                  * zone.  inode atime/mtime is updated in-place and thus
  654                  * buffers containing inodes must be synchronized as
  655                  * meta-buffers, same as buffers containing B-Tree info.
  656                  */
  657                 iotype = HAMMER_STRUCTURE_META_BUFFER;
  658                 break;
  659         }
  660 
  661         /*
  662          * Handle blockmap offset translations
  663          */
  664         if (zone >= HAMMER_ZONE_BTREE_INDEX) {
  665                 zone2_offset = hammer_blockmap_lookup(hmp, buf_offset, errorp);
  666         } else if (zone == HAMMER_ZONE_UNDO_INDEX) {
  667                 zone2_offset = hammer_undo_lookup(hmp, buf_offset, errorp);
  668         } else {
  669                 KKASSERT(zone == HAMMER_ZONE_RAW_BUFFER_INDEX);
  670                 zone2_offset = buf_offset;
  671                 *errorp = 0;
  672         }
  673         if (*errorp)
  674                 return(NULL);
  675 
  676         /*
  677          * NOTE: zone2_offset and maxbuf_off are both full zone-2 offset
  678          * specifications.
  679          */
  680         KKASSERT((zone2_offset & HAMMER_OFF_ZONE_MASK) ==
  681                  HAMMER_ZONE_RAW_BUFFER);
  682         vol_no = HAMMER_VOL_DECODE(zone2_offset);
  683         volume = hammer_get_volume(hmp, vol_no, errorp);
  684         if (volume == NULL)
  685                 return(NULL);
  686 
  687         KKASSERT(zone2_offset < volume->maxbuf_off);
  688 
  689         /*
  690          * Allocate a new buffer structure.  We will check for races later.
  691          */
  692         ++hammer_count_buffers;
  693         buffer = kmalloc(sizeof(*buffer), hmp->m_misc,
  694                          M_WAITOK|M_ZERO|M_USE_RESERVE);
  695         buffer->zone2_offset = zone2_offset;
  696         buffer->zoneX_offset = buf_offset;
  697 
  698         hammer_io_init(&buffer->io, volume, iotype);
  699         buffer->io.offset = volume->ondisk->vol_buf_beg +
  700                             (zone2_offset & HAMMER_OFF_SHORT_MASK);
  701         buffer->io.bytes = bytes;
  702         TAILQ_INIT(&buffer->clist);
  703         hammer_ref_interlock_true(&buffer->io.lock);
  704 
  705         /*
  706          * Insert the buffer into the RB tree and handle late collisions.
  707          */
  708         if (RB_INSERT(hammer_buf_rb_tree, &hmp->rb_bufs_root, buffer)) {
  709                 hammer_rel_volume(volume, 0);
  710                 buffer->io.volume = NULL;                       /* safety */
  711                 if (hammer_rel_interlock(&buffer->io.lock, 1))  /* safety */
  712                         hammer_rel_interlock_done(&buffer->io.lock, 1);
  713                 --hammer_count_buffers;
  714                 kfree(buffer, hmp->m_misc);
  715                 goto again;
  716         }
  717         atomic_add_int(&hammer_count_refedbufs, 1);
  718 found:
  719 
  720         /*
  721          * The buffer is referenced and interlocked.  Load the buffer
  722          * if necessary.  hammer_load_buffer() deals with the interlock
  723          * and, if an error is returned, also deals with the ref.
  724          */
  725         if (buffer->ondisk == NULL) {
  726                 *errorp = hammer_load_buffer(buffer, isnew);
  727                 if (*errorp)
  728                         buffer = NULL;
  729         } else {
  730                 hammer_io_advance(&buffer->io);
  731                 hammer_ref_interlock_done(&buffer->io.lock);
  732                 *errorp = 0;
  733         }
  734         return(buffer);
  735 }
  736 
  737 /*
  738  * This is used by the direct-read code to deal with large-data buffers
  739  * created by the reblocker and mirror-write code.  The direct-read code
  740  * bypasses the HAMMER buffer subsystem and so any aliased dirty or write-
  741  * running hammer buffers must be fully synced to disk before we can issue
  742  * the direct-read.
  743  *
  744  * This code path is not considered critical as only the rebocker and
  745  * mirror-write code will create large-data buffers via the HAMMER buffer
  746  * subsystem.  They do that because they operate at the B-Tree level and
  747  * do not access the vnode/inode structures.
  748  */
  749 void
  750 hammer_sync_buffers(hammer_mount_t hmp, hammer_off_t base_offset, int bytes)
  751 {
  752         hammer_buffer_t buffer;
  753         int error;
  754 
  755         KKASSERT((base_offset & HAMMER_OFF_ZONE_MASK) ==
  756                  HAMMER_ZONE_LARGE_DATA);
  757 
  758         while (bytes > 0) {
  759                 buffer = RB_LOOKUP(hammer_buf_rb_tree, &hmp->rb_bufs_root,
  760                                    base_offset);
  761                 if (buffer && (buffer->io.modified || buffer->io.running)) {
  762                         error = hammer_ref_buffer(buffer);
  763                         if (error == 0) {
  764                                 hammer_io_wait(&buffer->io);
  765                                 if (buffer->io.modified) {
  766                                         hammer_io_write_interlock(&buffer->io);
  767                                         hammer_io_flush(&buffer->io, 0);
  768                                         hammer_io_done_interlock(&buffer->io);
  769                                         hammer_io_wait(&buffer->io);
  770                                 }
  771                                 hammer_rel_buffer(buffer, 0);
  772                         }
  773                 }
  774                 base_offset += HAMMER_BUFSIZE;
  775                 bytes -= HAMMER_BUFSIZE;
  776         }
  777 }
  778 
  779 /*
  780  * Destroy all buffers covering the specified zoneX offset range.  This
  781  * is called when the related blockmap layer2 entry is freed or when
  782  * a direct write bypasses our buffer/buffer-cache subsystem.
  783  *
  784  * The buffers may be referenced by the caller itself.  Setting reclaim
  785  * will cause the buffer to be destroyed when it's ref count reaches zero.
  786  *
  787  * Return 0 on success, EAGAIN if some buffers could not be destroyed due
  788  * to additional references held by other threads, or some other (typically
  789  * fatal) error.
  790  */
  791 int
  792 hammer_del_buffers(hammer_mount_t hmp, hammer_off_t base_offset,
  793                    hammer_off_t zone2_offset, int bytes,
  794                    int report_conflicts)
  795 {
  796         hammer_buffer_t buffer;
  797         hammer_volume_t volume;
  798         int vol_no;
  799         int error;
  800         int ret_error;
  801 
  802         vol_no = HAMMER_VOL_DECODE(zone2_offset);
  803         volume = hammer_get_volume(hmp, vol_no, &ret_error);
  804         KKASSERT(ret_error == 0);
  805 
  806         while (bytes > 0) {
  807                 buffer = RB_LOOKUP(hammer_buf_rb_tree, &hmp->rb_bufs_root,
  808                                    base_offset);
  809                 if (buffer) {
  810                         error = hammer_ref_buffer(buffer);
  811                         if (hammer_debug_general & 0x20000) {
  812                                 kprintf("hammer: delbufr %016jx "
  813                                         "rerr=%d 1ref=%d\n",
  814                                         (intmax_t)buffer->zoneX_offset,
  815                                         error,
  816                                         hammer_oneref(&buffer->io.lock));
  817                         }
  818                         if (error == 0 && !hammer_oneref(&buffer->io.lock)) {
  819                                 error = EAGAIN;
  820                                 hammer_rel_buffer(buffer, 0);
  821                         }
  822                         if (error == 0) {
  823                                 KKASSERT(buffer->zone2_offset == zone2_offset);
  824                                 hammer_io_clear_modify(&buffer->io, 1);
  825                                 buffer->io.reclaim = 1;
  826                                 buffer->io.waitdep = 1;
  827                                 KKASSERT(buffer->io.volume == volume);
  828                                 hammer_rel_buffer(buffer, 0);
  829                         }
  830                 } else {
  831                         error = hammer_io_inval(volume, zone2_offset);
  832                 }
  833                 if (error) {
  834                         ret_error = error;
  835                         if (report_conflicts ||
  836                             (hammer_debug_general & 0x8000)) {
  837                                 kprintf("hammer_del_buffers: unable to "
  838                                         "invalidate %016llx buffer=%p rep=%d\n",
  839                                         (long long)base_offset,
  840                                         buffer, report_conflicts);
  841                         }
  842                 }
  843                 base_offset += HAMMER_BUFSIZE;
  844                 zone2_offset += HAMMER_BUFSIZE;
  845                 bytes -= HAMMER_BUFSIZE;
  846         }
  847         hammer_rel_volume(volume, 0);
  848         return (ret_error);
  849 }
  850 
  851 /*
  852  * Given a referenced and interlocked buffer load/validate the data.
  853  *
  854  * The buffer interlock will be released on return.  If an error is
  855  * returned the buffer reference will also be released (and the buffer
  856  * pointer will thus be stale).
  857  */
  858 static int
  859 hammer_load_buffer(hammer_buffer_t buffer, int isnew)
  860 {
  861         hammer_volume_t volume;
  862         int error;
  863 
  864         /*
  865          * Load the buffer's on-disk info
  866          */
  867         volume = buffer->io.volume;
  868 
  869         if (hammer_debug_io & 0x0004) {
  870                 kprintf("load_buffer %016llx %016llx isnew=%d od=%p\n",
  871                         (long long)buffer->zoneX_offset,
  872                         (long long)buffer->zone2_offset,
  873                         isnew, buffer->ondisk);
  874         }
  875 
  876         if (buffer->ondisk == NULL) {
  877                 /*
  878                  * Issue the read or generate a new buffer.  When reading
  879                  * the limit argument controls any read-ahead clustering
  880                  * hammer_io_read() is allowed to do.
  881                  *
  882                  * We cannot read-ahead in the large-data zone and we cannot
  883                  * cross a largeblock boundary as the next largeblock might
  884                  * use a different buffer size.
  885                  */
  886                 if (isnew) {
  887                         error = hammer_io_new(volume->devvp, &buffer->io);
  888                 } else if ((buffer->zoneX_offset & HAMMER_OFF_ZONE_MASK) ==
  889                            HAMMER_ZONE_LARGE_DATA) {
  890                         error = hammer_io_read(volume->devvp, &buffer->io,
  891                                                buffer->io.bytes);
  892                 } else {
  893                         hammer_off_t limit;
  894 
  895                         limit = (buffer->zone2_offset +
  896                                  HAMMER_LARGEBLOCK_MASK64) &
  897                                 ~HAMMER_LARGEBLOCK_MASK64;
  898                         limit -= buffer->zone2_offset;
  899                         error = hammer_io_read(volume->devvp, &buffer->io,
  900                                                limit);
  901                 }
  902                 if (error == 0)
  903                         buffer->ondisk = (void *)buffer->io.bp->b_data;
  904         } else if (isnew) {
  905                 error = hammer_io_new(volume->devvp, &buffer->io);
  906         } else {
  907                 error = 0;
  908         }
  909         if (error == 0) {
  910                 hammer_io_advance(&buffer->io);
  911                 hammer_ref_interlock_done(&buffer->io.lock);
  912         } else {
  913                 hammer_rel_buffer(buffer, 1);
  914         }
  915         return (error);
  916 }
  917 
  918 /*
  919  * NOTE: Called from RB_SCAN, must return >= 0 for scan to continue.
  920  * This routine is only called during unmount or when a volume is
  921  * removed.
  922  *
  923  * If data != NULL, it specifies a volume whoose buffers should
  924  * be unloaded.
  925  */
  926 int
  927 hammer_unload_buffer(hammer_buffer_t buffer, void *data)
  928 {
  929         struct hammer_volume *volume = (struct hammer_volume *) data;
  930 
  931         /*
  932          * If volume != NULL we are only interested in unloading buffers
  933          * associated with a particular volume.
  934          */
  935         if (volume != NULL && volume != buffer->io.volume)
  936                 return 0;
  937 
  938         /*
  939          * Clean up the persistent ref ioerror might have on the buffer
  940          * and acquire a ref.  Expect a 0->1 transition.
  941          */
  942         if (buffer->io.ioerror) {
  943                 hammer_io_clear_error_noassert(&buffer->io);
  944                 atomic_add_int(&hammer_count_refedbufs, -1);
  945         }
  946         hammer_ref_interlock_true(&buffer->io.lock);
  947         atomic_add_int(&hammer_count_refedbufs, 1);
  948 
  949         /*
  950          * We must not flush a dirty buffer to disk on umount.  It should
  951          * have already been dealt with by the flusher, or we may be in
  952          * catastrophic failure.
  953          *
  954          * We must set waitdep to ensure that a running buffer is waited
  955          * on and released prior to us trying to unload the volume.
  956          */
  957         hammer_io_clear_modify(&buffer->io, 1);
  958         hammer_flush_buffer_nodes(buffer);
  959         buffer->io.waitdep = 1;
  960         hammer_rel_buffer(buffer, 1);
  961         return(0);
  962 }
  963 
  964 /*
  965  * Reference a buffer that is either already referenced or via a specially
  966  * handled pointer (aka cursor->buffer).
  967  */
  968 int
  969 hammer_ref_buffer(hammer_buffer_t buffer)
  970 {
  971         hammer_mount_t hmp;
  972         int error;
  973         int locked;
  974 
  975         /*
  976          * Acquire a ref, plus the buffer will be interlocked on the
  977          * 0->1 transition.
  978          */
  979         locked = hammer_ref_interlock(&buffer->io.lock);
  980         hmp = buffer->io.hmp;
  981 
  982         /*
  983          * At this point a biodone() will not touch the buffer other then
  984          * incidental bits.  However, lose_list can be modified via
  985          * a biodone() interrupt.
  986          *
  987          * No longer loose.  lose_list requires the io_token.
  988          */
  989         if (buffer->io.mod_root == &hmp->lose_root) {
  990                 lwkt_gettoken(&hmp->io_token);
  991                 if (buffer->io.mod_root == &hmp->lose_root) {
  992                         RB_REMOVE(hammer_mod_rb_tree,
  993                                   buffer->io.mod_root, &buffer->io);
  994                         buffer->io.mod_root = NULL;
  995                 }
  996                 lwkt_reltoken(&hmp->io_token);
  997         }
  998 
  999         if (locked) {
 1000                 atomic_add_int(&hammer_count_refedbufs, 1);
 1001                 error = hammer_load_buffer(buffer, 0);
 1002                 /* NOTE: on error the buffer pointer is stale */
 1003         } else {
 1004                 error = 0;
 1005         }
 1006         return(error);
 1007 }
 1008 
 1009 /*
 1010  * Release a reference on the buffer.  On the 1->0 transition the
 1011  * underlying IO will be released but the data reference is left
 1012  * cached.
 1013  *
 1014  * Only destroy the structure itself if the related buffer cache buffer
 1015  * was disassociated from it.  This ties the management of the structure
 1016  * to the buffer cache subsystem.  buffer->ondisk determines whether the
 1017  * embedded io is referenced or not.
 1018  */
 1019 void
 1020 hammer_rel_buffer(hammer_buffer_t buffer, int locked)
 1021 {
 1022         hammer_volume_t volume;
 1023         hammer_mount_t hmp;
 1024         struct buf *bp = NULL;
 1025         int freeme = 0;
 1026 
 1027         hmp = buffer->io.hmp;
 1028 
 1029         if (hammer_rel_interlock(&buffer->io.lock, locked) == 0)
 1030                 return;
 1031 
 1032         /*
 1033          * hammer_count_refedbufs accounting.  Decrement if we are in
 1034          * the error path or if CHECK is clear.
 1035          *
 1036          * If we are not in the error path and CHECK is set the caller
 1037          * probably just did a hammer_ref() and didn't account for it,
 1038          * so we don't account for the loss here.
 1039          */
 1040         if (locked || (buffer->io.lock.refs & HAMMER_REFS_CHECK) == 0)
 1041                 atomic_add_int(&hammer_count_refedbufs, -1);
 1042 
 1043         /*
 1044          * If the caller locked us or the normal released transitions
 1045          * from 1->0 (and acquired the lock) attempt to release the
 1046          * io.  If the called locked us we tell hammer_io_release()
 1047          * to flush (which would be the unload or failure path).
 1048          */
 1049         bp = hammer_io_release(&buffer->io, locked);
 1050 
 1051         /*
 1052          * If the buffer has no bp association and no refs we can destroy
 1053          * it.
 1054          *
 1055          * NOTE: It is impossible for any associated B-Tree nodes to have
 1056          * refs if the buffer has no additional refs.
 1057          */
 1058         if (buffer->io.bp == NULL && hammer_norefs(&buffer->io.lock)) {
 1059                 RB_REMOVE(hammer_buf_rb_tree,
 1060                           &buffer->io.hmp->rb_bufs_root,
 1061                           buffer);
 1062                 volume = buffer->io.volume;
 1063                 buffer->io.volume = NULL; /* sanity */
 1064                 hammer_rel_volume(volume, 0);
 1065                 hammer_io_clear_modlist(&buffer->io);
 1066                 hammer_flush_buffer_nodes(buffer);
 1067                 KKASSERT(TAILQ_EMPTY(&buffer->clist));
 1068                 freeme = 1;
 1069         }
 1070 
 1071         /*
 1072          * Cleanup
 1073          */
 1074         hammer_rel_interlock_done(&buffer->io.lock, locked);
 1075         if (bp)
 1076                 brelse(bp);
 1077         if (freeme) {
 1078                 --hammer_count_buffers;
 1079                 kfree(buffer, hmp->m_misc);
 1080         }
 1081 }
 1082 
 1083 /*
 1084  * Access the filesystem buffer containing the specified hammer offset.
 1085  * buf_offset is a conglomeration of the volume number and vol_buf_beg
 1086  * relative buffer offset.  It must also have bit 55 set to be valid.
 1087  * (see hammer_off_t in hammer_disk.h).
 1088  *
 1089  * Any prior buffer in *bufferp will be released and replaced by the
 1090  * requested buffer.
 1091  *
 1092  * NOTE: The buffer is indexed via its zoneX_offset but we allow the
 1093  * passed cached *bufferp to match against either zoneX or zone2.
 1094  */
 1095 static __inline
 1096 void *
 1097 _hammer_bread(hammer_mount_t hmp, hammer_off_t buf_offset, int bytes,
 1098              int *errorp, struct hammer_buffer **bufferp)
 1099 {
 1100         hammer_buffer_t buffer;
 1101         int32_t xoff = (int32_t)buf_offset & HAMMER_BUFMASK;
 1102 
 1103         buf_offset &= ~HAMMER_BUFMASK64;
 1104         KKASSERT((buf_offset & HAMMER_OFF_ZONE_MASK) != 0);
 1105 
 1106         buffer = *bufferp;
 1107         if (buffer == NULL || (buffer->zone2_offset != buf_offset &&
 1108                                buffer->zoneX_offset != buf_offset)) {
 1109                 if (buffer)
 1110                         hammer_rel_buffer(buffer, 0);
 1111                 buffer = hammer_get_buffer(hmp, buf_offset, bytes, 0, errorp);
 1112                 *bufferp = buffer;
 1113         } else {
 1114                 *errorp = 0;
 1115         }
 1116 
 1117         /*
 1118          * Return a pointer to the buffer data.
 1119          */
 1120         if (buffer == NULL)
 1121                 return(NULL);
 1122         else
 1123                 return((char *)buffer->ondisk + xoff);
 1124 }
 1125 
 1126 void *
 1127 hammer_bread(hammer_mount_t hmp, hammer_off_t buf_offset,
 1128              int *errorp, struct hammer_buffer **bufferp)
 1129 {
 1130         return(_hammer_bread(hmp, buf_offset, HAMMER_BUFSIZE, errorp, bufferp));
 1131 }
 1132 
 1133 void *
 1134 hammer_bread_ext(hammer_mount_t hmp, hammer_off_t buf_offset, int bytes,
 1135                  int *errorp, struct hammer_buffer **bufferp)
 1136 {
 1137         bytes = (bytes + HAMMER_BUFMASK) & ~HAMMER_BUFMASK;
 1138         return(_hammer_bread(hmp, buf_offset, bytes, errorp, bufferp));
 1139 }
 1140 
 1141 /*
 1142  * Access the filesystem buffer containing the specified hammer offset.
 1143  * No disk read operation occurs.  The result buffer may contain garbage.
 1144  *
 1145  * Any prior buffer in *bufferp will be released and replaced by the
 1146  * requested buffer.
 1147  *
 1148  * This function marks the buffer dirty but does not increment its
 1149  * modify_refs count.
 1150  */
 1151 static __inline
 1152 void *
 1153 _hammer_bnew(hammer_mount_t hmp, hammer_off_t buf_offset, int bytes,
 1154              int *errorp, struct hammer_buffer **bufferp)
 1155 {
 1156         hammer_buffer_t buffer;
 1157         int32_t xoff = (int32_t)buf_offset & HAMMER_BUFMASK;
 1158 
 1159         buf_offset &= ~HAMMER_BUFMASK64;
 1160 
 1161         buffer = *bufferp;
 1162         if (buffer == NULL || (buffer->zone2_offset != buf_offset &&
 1163                                buffer->zoneX_offset != buf_offset)) {
 1164                 if (buffer)
 1165                         hammer_rel_buffer(buffer, 0);
 1166                 buffer = hammer_get_buffer(hmp, buf_offset, bytes, 1, errorp);
 1167                 *bufferp = buffer;
 1168         } else {
 1169                 *errorp = 0;
 1170         }
 1171 
 1172         /*
 1173          * Return a pointer to the buffer data.
 1174          */
 1175         if (buffer == NULL)
 1176                 return(NULL);
 1177         else
 1178                 return((char *)buffer->ondisk + xoff);
 1179 }
 1180 
 1181 void *
 1182 hammer_bnew(hammer_mount_t hmp, hammer_off_t buf_offset,
 1183              int *errorp, struct hammer_buffer **bufferp)
 1184 {
 1185         return(_hammer_bnew(hmp, buf_offset, HAMMER_BUFSIZE, errorp, bufferp));
 1186 }
 1187 
 1188 void *
 1189 hammer_bnew_ext(hammer_mount_t hmp, hammer_off_t buf_offset, int bytes,
 1190                 int *errorp, struct hammer_buffer **bufferp)
 1191 {
 1192         bytes = (bytes + HAMMER_BUFMASK) & ~HAMMER_BUFMASK;
 1193         return(_hammer_bnew(hmp, buf_offset, bytes, errorp, bufferp));
 1194 }
 1195 
 1196 /************************************************************************
 1197  *                              NODES                                   *
 1198  ************************************************************************
 1199  *
 1200  * Manage B-Tree nodes.  B-Tree nodes represent the primary indexing
 1201  * method used by the HAMMER filesystem.
 1202  *
 1203  * Unlike other HAMMER structures, a hammer_node can be PASSIVELY
 1204  * associated with its buffer, and will only referenced the buffer while
 1205  * the node itself is referenced.
 1206  *
 1207  * A hammer_node can also be passively associated with other HAMMER
 1208  * structures, such as inodes, while retaining 0 references.  These
 1209  * associations can be cleared backwards using a pointer-to-pointer in
 1210  * the hammer_node.
 1211  *
 1212  * This allows the HAMMER implementation to cache hammer_nodes long-term
 1213  * and short-cut a great deal of the infrastructure's complexity.  In
 1214  * most cases a cached node can be reacquired without having to dip into
 1215  * either the buffer or cluster management code.
 1216  *
 1217  * The caller must pass a referenced cluster on call and will retain
 1218  * ownership of the reference on return.  The node will acquire its own
 1219  * additional references, if necessary.
 1220  */
 1221 hammer_node_t
 1222 hammer_get_node(hammer_transaction_t trans, hammer_off_t node_offset,
 1223                 int isnew, int *errorp)
 1224 {
 1225         hammer_mount_t hmp = trans->hmp;
 1226         hammer_node_t node;
 1227         int doload;
 1228 
 1229         KKASSERT((node_offset & HAMMER_OFF_ZONE_MASK) == HAMMER_ZONE_BTREE);
 1230 
 1231         /*
 1232          * Locate the structure, allocating one if necessary.
 1233          */
 1234 again:
 1235         node = RB_LOOKUP(hammer_nod_rb_tree, &hmp->rb_nods_root, node_offset);
 1236         if (node == NULL) {
 1237                 ++hammer_count_nodes;
 1238                 node = kmalloc(sizeof(*node), hmp->m_misc, M_WAITOK|M_ZERO|M_USE_RESERVE);
 1239                 node->node_offset = node_offset;
 1240                 node->hmp = hmp;
 1241                 TAILQ_INIT(&node->cursor_list);
 1242                 TAILQ_INIT(&node->cache_list);
 1243                 if (RB_INSERT(hammer_nod_rb_tree, &hmp->rb_nods_root, node)) {
 1244                         --hammer_count_nodes;
 1245                         kfree(node, hmp->m_misc);
 1246                         goto again;
 1247                 }
 1248                 doload = hammer_ref_interlock_true(&node->lock);
 1249         } else {
 1250                 doload = hammer_ref_interlock(&node->lock);
 1251         }
 1252         if (doload) {
 1253                 *errorp = hammer_load_node(trans, node, isnew);
 1254                 trans->flags |= HAMMER_TRANSF_DIDIO;
 1255                 if (*errorp)
 1256                         node = NULL;
 1257         } else {
 1258                 KKASSERT(node->ondisk);
 1259                 *errorp = 0;
 1260                 hammer_io_advance(&node->buffer->io);
 1261         }
 1262         return(node);
 1263 }
 1264 
 1265 /*
 1266  * Reference an already-referenced node.  0->1 transitions should assert
 1267  * so we do not have to deal with hammer_ref() setting CHECK.
 1268  */
 1269 void
 1270 hammer_ref_node(hammer_node_t node)
 1271 {
 1272         KKASSERT(hammer_isactive(&node->lock) && node->ondisk != NULL);
 1273         hammer_ref(&node->lock);
 1274 }
 1275 
 1276 /*
 1277  * Load a node's on-disk data reference.  Called with the node referenced
 1278  * and interlocked.
 1279  *
 1280  * On return the node interlock will be unlocked.  If a non-zero error code
 1281  * is returned the node will also be dereferenced (and the caller's pointer
 1282  * will be stale).
 1283  */
 1284 static int
 1285 hammer_load_node(hammer_transaction_t trans, hammer_node_t node, int isnew)
 1286 {
 1287         hammer_buffer_t buffer;
 1288         hammer_off_t buf_offset;
 1289         int error;
 1290 
 1291         error = 0;
 1292         if (node->ondisk == NULL) {
 1293                 /*
 1294                  * This is a little confusing but the jist is that
 1295                  * node->buffer determines whether the node is on
 1296                  * the buffer's clist and node->ondisk determines
 1297                  * whether the buffer is referenced.
 1298                  *
 1299                  * We could be racing a buffer release, in which case
 1300                  * node->buffer may become NULL while we are blocked
 1301                  * referencing the buffer.
 1302                  */
 1303                 if ((buffer = node->buffer) != NULL) {
 1304                         error = hammer_ref_buffer(buffer);
 1305                         if (error == 0 && node->buffer == NULL) {
 1306                                 TAILQ_INSERT_TAIL(&buffer->clist,
 1307                                                   node, entry);
 1308                                 node->buffer = buffer;
 1309                         }
 1310                 } else {
 1311                         buf_offset = node->node_offset & ~HAMMER_BUFMASK64;
 1312                         buffer = hammer_get_buffer(node->hmp, buf_offset,
 1313                                                    HAMMER_BUFSIZE, 0, &error);
 1314                         if (buffer) {
 1315                                 KKASSERT(error == 0);
 1316                                 TAILQ_INSERT_TAIL(&buffer->clist,
 1317                                                   node, entry);
 1318                                 node->buffer = buffer;
 1319                         }
 1320                 }
 1321                 if (error)
 1322                         goto failed;
 1323                 node->ondisk = (void *)((char *)buffer->ondisk +
 1324                                         (node->node_offset & HAMMER_BUFMASK));
 1325 
 1326                 /*
 1327                  * Check CRC.  NOTE: Neither flag is set and the CRC is not
 1328                  * generated on new B-Tree nodes.
 1329                  */
 1330                 if (isnew == 0 && 
 1331                     (node->flags & HAMMER_NODE_CRCANY) == 0) {
 1332                         if (hammer_crc_test_btree(node->ondisk) == 0) {
 1333                                 if (hammer_debug_critical)
 1334                                         Debugger("CRC FAILED: B-TREE NODE");
 1335                                 node->flags |= HAMMER_NODE_CRCBAD;
 1336                         } else {
 1337                                 node->flags |= HAMMER_NODE_CRCGOOD;
 1338                         }
 1339                 }
 1340         }
 1341         if (node->flags & HAMMER_NODE_CRCBAD) {
 1342                 if (trans->flags & HAMMER_TRANSF_CRCDOM)
 1343                         error = EDOM;
 1344                 else
 1345                         error = EIO;
 1346         }
 1347 failed:
 1348         if (error) {
 1349                 _hammer_rel_node(node, 1);
 1350         } else {
 1351                 hammer_ref_interlock_done(&node->lock);
 1352         }
 1353         return (error);
 1354 }
 1355 
 1356 /*
 1357  * Safely reference a node, interlock against flushes via the IO subsystem.
 1358  */
 1359 hammer_node_t
 1360 hammer_ref_node_safe(hammer_transaction_t trans, hammer_node_cache_t cache,
 1361                      int *errorp)
 1362 {
 1363         hammer_node_t node;
 1364         int doload;
 1365 
 1366         node = cache->node;
 1367         if (node != NULL) {
 1368                 doload = hammer_ref_interlock(&node->lock);
 1369                 if (doload) {
 1370                         *errorp = hammer_load_node(trans, node, 0);
 1371                         if (*errorp)
 1372                                 node = NULL;
 1373                 } else {
 1374                         KKASSERT(node->ondisk);
 1375                         if (node->flags & HAMMER_NODE_CRCBAD) {
 1376                                 if (trans->flags & HAMMER_TRANSF_CRCDOM)
 1377                                         *errorp = EDOM;
 1378                                 else
 1379                                         *errorp = EIO;
 1380                                 _hammer_rel_node(node, 0);
 1381                                 node = NULL;
 1382                         } else {
 1383                                 *errorp = 0;
 1384                         }
 1385                 }
 1386         } else {
 1387                 *errorp = ENOENT;
 1388         }
 1389         return(node);
 1390 }
 1391 
 1392 /*
 1393  * Release a hammer_node.  On the last release the node dereferences
 1394  * its underlying buffer and may or may not be destroyed.
 1395  *
 1396  * If locked is non-zero the passed node has been interlocked by the
 1397  * caller and we are in the failure/unload path, otherwise it has not and
 1398  * we are doing a normal release.
 1399  *
 1400  * This function will dispose of the interlock and the reference.
 1401  * On return the node pointer is stale.
 1402  */
 1403 void
 1404 _hammer_rel_node(hammer_node_t node, int locked)
 1405 {
 1406         hammer_buffer_t buffer;
 1407 
 1408         /*
 1409          * Deref the node.  If this isn't the 1->0 transition we're basically
 1410          * done.  If locked is non-zero this function will just deref the
 1411          * locked node and return TRUE, otherwise it will deref the locked
 1412          * node and either lock and return TRUE on the 1->0 transition or
 1413          * not lock and return FALSE.
 1414          */
 1415         if (hammer_rel_interlock(&node->lock, locked) == 0)
 1416                 return;
 1417 
 1418         /*
 1419          * Either locked was non-zero and we are interlocked, or the
 1420          * hammer_rel_interlock() call returned non-zero and we are
 1421          * interlocked.
 1422          *
 1423          * The ref-count must still be decremented if locked != 0 so
 1424          * the cleanup required still varies a bit.
 1425          *
 1426          * hammer_flush_node() when called with 1 or 2 will dispose of
 1427          * the lock and possible ref-count.
 1428          */
 1429         if (node->ondisk == NULL) {
 1430                 hammer_flush_node(node, locked + 1);
 1431                 /* node is stale now */
 1432                 return;
 1433         }
 1434 
 1435         /*
 1436          * Do not disassociate the node from the buffer if it represents
 1437          * a modified B-Tree node that still needs its crc to be generated.
 1438          */
 1439         if (node->flags & HAMMER_NODE_NEEDSCRC) {
 1440                 hammer_rel_interlock_done(&node->lock, locked);
 1441                 return;
 1442         }
 1443 
 1444         /*
 1445          * Do final cleanups and then either destroy the node and leave it
 1446          * passively cached.  The buffer reference is removed regardless.
 1447          */
 1448         buffer = node->buffer;
 1449         node->ondisk = NULL;
 1450 
 1451         if ((node->flags & HAMMER_NODE_FLUSH) == 0) {
 1452                 /*
 1453                  * Normal release.
 1454                  */
 1455                 hammer_rel_interlock_done(&node->lock, locked);
 1456         } else {
 1457                 /*
 1458                  * Destroy the node.
 1459                  */
 1460                 hammer_flush_node(node, locked + 1);
 1461                 /* node is stale */
 1462 
 1463         }
 1464         hammer_rel_buffer(buffer, 0);
 1465 }
 1466 
 1467 void
 1468 hammer_rel_node(hammer_node_t node)
 1469 {
 1470         _hammer_rel_node(node, 0);
 1471 }
 1472 
 1473 /*
 1474  * Free space on-media associated with a B-Tree node.
 1475  */
 1476 void
 1477 hammer_delete_node(hammer_transaction_t trans, hammer_node_t node)
 1478 {
 1479         KKASSERT((node->flags & HAMMER_NODE_DELETED) == 0);
 1480         node->flags |= HAMMER_NODE_DELETED;
 1481         hammer_blockmap_free(trans, node->node_offset, sizeof(*node->ondisk));
 1482 }
 1483 
 1484 /*
 1485  * Passively cache a referenced hammer_node.  The caller may release
 1486  * the node on return.
 1487  */
 1488 void
 1489 hammer_cache_node(hammer_node_cache_t cache, hammer_node_t node)
 1490 {
 1491         /*
 1492          * If the node doesn't exist, or is being deleted, don't cache it!
 1493          *
 1494          * The node can only ever be NULL in the I/O failure path.
 1495          */
 1496         if (node == NULL || (node->flags & HAMMER_NODE_DELETED))
 1497                 return;
 1498         if (cache->node == node)
 1499                 return;
 1500         while (cache->node)
 1501                 hammer_uncache_node(cache);
 1502         if (node->flags & HAMMER_NODE_DELETED)
 1503                 return;
 1504         cache->node = node;
 1505         TAILQ_INSERT_TAIL(&node->cache_list, cache, entry);
 1506 }
 1507 
 1508 void
 1509 hammer_uncache_node(hammer_node_cache_t cache)
 1510 {
 1511         hammer_node_t node;
 1512 
 1513         if ((node = cache->node) != NULL) {
 1514                 TAILQ_REMOVE(&node->cache_list, cache, entry);
 1515                 cache->node = NULL;
 1516                 if (TAILQ_EMPTY(&node->cache_list))
 1517                         hammer_flush_node(node, 0);
 1518         }
 1519 }
 1520 
 1521 /*
 1522  * Remove a node's cache references and destroy the node if it has no
 1523  * other references or backing store.
 1524  *
 1525  * locked == 0  Normal unlocked operation
 1526  * locked == 1  Call hammer_rel_interlock_done(..., 0);
 1527  * locked == 2  Call hammer_rel_interlock_done(..., 1);
 1528  *
 1529  * XXX for now this isn't even close to being MPSAFE so the refs check
 1530  *     is sufficient.
 1531  */
 1532 void
 1533 hammer_flush_node(hammer_node_t node, int locked)
 1534 {
 1535         hammer_node_cache_t cache;
 1536         hammer_buffer_t buffer;
 1537         hammer_mount_t hmp = node->hmp;
 1538         int dofree;
 1539 
 1540         while ((cache = TAILQ_FIRST(&node->cache_list)) != NULL) {
 1541                 TAILQ_REMOVE(&node->cache_list, cache, entry);
 1542                 cache->node = NULL;
 1543         }
 1544 
 1545         /*
 1546          * NOTE: refs is predisposed if another thread is blocking and
 1547          *       will be larger than 0 in that case.  We aren't MPSAFE
 1548          *       here.
 1549          */
 1550         if (node->ondisk == NULL && hammer_norefs(&node->lock)) {
 1551                 KKASSERT((node->flags & HAMMER_NODE_NEEDSCRC) == 0);
 1552                 RB_REMOVE(hammer_nod_rb_tree, &node->hmp->rb_nods_root, node);
 1553                 if ((buffer = node->buffer) != NULL) {
 1554                         node->buffer = NULL;
 1555                         TAILQ_REMOVE(&buffer->clist, node, entry);
 1556                         /* buffer is unreferenced because ondisk is NULL */
 1557                 }
 1558                 dofree = 1;
 1559         } else {
 1560                 dofree = 0;
 1561         }
 1562 
 1563         /*
 1564          * Deal with the interlock if locked == 1 or locked == 2.
 1565          */
 1566         if (locked)
 1567                 hammer_rel_interlock_done(&node->lock, locked - 1);
 1568 
 1569         /*
 1570          * Destroy if requested
 1571          */
 1572         if (dofree) {
 1573                 --hammer_count_nodes;
 1574                 kfree(node, hmp->m_misc);
 1575         }
 1576 }
 1577 
 1578 /*
 1579  * Flush passively cached B-Tree nodes associated with this buffer.
 1580  * This is only called when the buffer is about to be destroyed, so
 1581  * none of the nodes should have any references.  The buffer is locked.
 1582  *
 1583  * We may be interlocked with the buffer.
 1584  */
 1585 void
 1586 hammer_flush_buffer_nodes(hammer_buffer_t buffer)
 1587 {
 1588         hammer_node_t node;
 1589 
 1590         while ((node = TAILQ_FIRST(&buffer->clist)) != NULL) {
 1591                 KKASSERT(node->ondisk == NULL);
 1592                 KKASSERT((node->flags & HAMMER_NODE_NEEDSCRC) == 0);
 1593 
 1594                 if (hammer_try_interlock_norefs(&node->lock)) {
 1595                         hammer_ref(&node->lock);
 1596                         node->flags |= HAMMER_NODE_FLUSH;
 1597                         _hammer_rel_node(node, 1);
 1598                 } else {
 1599                         KKASSERT(node->buffer != NULL);
 1600                         buffer = node->buffer;
 1601                         node->buffer = NULL;
 1602                         TAILQ_REMOVE(&buffer->clist, node, entry);
 1603                         /* buffer is unreferenced because ondisk is NULL */
 1604                 }
 1605         }
 1606 }
 1607 
 1608 
 1609 /************************************************************************
 1610  *                              ALLOCATORS                              *
 1611  ************************************************************************/
 1612 
 1613 /*
 1614  * Allocate a B-Tree node.
 1615  */
 1616 hammer_node_t
 1617 hammer_alloc_btree(hammer_transaction_t trans, hammer_off_t hint, int *errorp)
 1618 {
 1619         hammer_buffer_t buffer = NULL;
 1620         hammer_node_t node = NULL;
 1621         hammer_off_t node_offset;
 1622 
 1623         node_offset = hammer_blockmap_alloc(trans, HAMMER_ZONE_BTREE_INDEX,
 1624                                             sizeof(struct hammer_node_ondisk),
 1625                                             hint, errorp);
 1626         if (*errorp == 0) {
 1627                 node = hammer_get_node(trans, node_offset, 1, errorp);
 1628                 hammer_modify_node_noundo(trans, node);
 1629                 bzero(node->ondisk, sizeof(*node->ondisk));
 1630                 hammer_modify_node_done(node);
 1631         }
 1632         if (buffer)
 1633                 hammer_rel_buffer(buffer, 0);
 1634         return(node);
 1635 }
 1636 
 1637 /*
 1638  * Allocate data.  If the address of a data buffer is supplied then
 1639  * any prior non-NULL *data_bufferp will be released and *data_bufferp
 1640  * will be set to the related buffer.  The caller must release it when
 1641  * finally done.  The initial *data_bufferp should be set to NULL by
 1642  * the caller.
 1643  *
 1644  * The caller is responsible for making hammer_modify*() calls on the
 1645  * *data_bufferp.
 1646  */
 1647 void *
 1648 hammer_alloc_data(hammer_transaction_t trans, int32_t data_len, 
 1649                   u_int16_t rec_type, hammer_off_t *data_offsetp,
 1650                   struct hammer_buffer **data_bufferp,
 1651                   hammer_off_t hint, int *errorp)
 1652 {
 1653         void *data;
 1654         int zone;
 1655 
 1656         /*
 1657          * Allocate data
 1658          */
 1659         if (data_len) {
 1660                 switch(rec_type) {
 1661                 case HAMMER_RECTYPE_INODE:
 1662                 case HAMMER_RECTYPE_DIRENTRY:
 1663                 case HAMMER_RECTYPE_EXT:
 1664                 case HAMMER_RECTYPE_FIX:
 1665                 case HAMMER_RECTYPE_PFS:
 1666                 case HAMMER_RECTYPE_SNAPSHOT:
 1667                 case HAMMER_RECTYPE_CONFIG:
 1668                         zone = HAMMER_ZONE_META_INDEX;
 1669                         break;
 1670                 case HAMMER_RECTYPE_DATA:
 1671                 case HAMMER_RECTYPE_DB:
 1672                         if (data_len <= HAMMER_BUFSIZE / 2) {
 1673                                 zone = HAMMER_ZONE_SMALL_DATA_INDEX;
 1674                         } else {
 1675                                 data_len = (data_len + HAMMER_BUFMASK) &
 1676                                            ~HAMMER_BUFMASK;
 1677                                 zone = HAMMER_ZONE_LARGE_DATA_INDEX;
 1678                         }
 1679                         break;
 1680                 default:
 1681                         panic("hammer_alloc_data: rec_type %04x unknown",
 1682                               rec_type);
 1683                         zone = 0;       /* NOT REACHED */
 1684                         break;
 1685                 }
 1686                 *data_offsetp = hammer_blockmap_alloc(trans, zone, data_len,
 1687                                                       hint, errorp);
 1688         } else {
 1689                 *data_offsetp = 0;
 1690         }
 1691         if (*errorp == 0 && data_bufferp) {
 1692                 if (data_len) {
 1693                         data = hammer_bread_ext(trans->hmp, *data_offsetp,
 1694                                                 data_len, errorp, data_bufferp);
 1695                 } else {
 1696                         data = NULL;
 1697                 }
 1698         } else {
 1699                 data = NULL;
 1700         }
 1701         return(data);
 1702 }
 1703 
 1704 /*
 1705  * Sync dirty buffers to the media and clean-up any loose ends.
 1706  *
 1707  * These functions do not start the flusher going, they simply
 1708  * queue everything up to the flusher.
 1709  */
 1710 static int hammer_sync_scan2(struct mount *mp, struct vnode *vp, void *data);
 1711 
 1712 int
 1713 hammer_queue_inodes_flusher(hammer_mount_t hmp, int waitfor)
 1714 {
 1715         struct hammer_sync_info info;
 1716 
 1717         info.error = 0;
 1718         info.waitfor = waitfor;
 1719         if (waitfor == MNT_WAIT) {
 1720                 vsyncscan(hmp->mp, VMSC_GETVP | VMSC_ONEPASS,
 1721                           hammer_sync_scan2, &info);
 1722         } else {
 1723                 vsyncscan(hmp->mp, VMSC_GETVP | VMSC_ONEPASS | VMSC_NOWAIT,
 1724                           hammer_sync_scan2, &info);
 1725         }
 1726         return(info.error);
 1727 }
 1728 
 1729 /*
 1730  * Filesystem sync.  If doing a synchronous sync make a second pass on
 1731  * the vnodes in case any were already flushing during the first pass,
 1732  * and activate the flusher twice (the second time brings the UNDO FIFO's
 1733  * start position up to the end position after the first call).
 1734  *
 1735  * If doing a lazy sync make just one pass on the vnode list, ignoring
 1736  * any new vnodes added to the list while the sync is in progress.
 1737  */
 1738 int
 1739 hammer_sync_hmp(hammer_mount_t hmp, int waitfor)
 1740 {
 1741         struct hammer_sync_info info;
 1742         int flags;
 1743 
 1744         flags = VMSC_GETVP;
 1745         if (waitfor & MNT_LAZY)
 1746                 flags |= VMSC_ONEPASS;
 1747 
 1748         info.error = 0;
 1749         info.waitfor = MNT_NOWAIT;
 1750         vsyncscan(hmp->mp, flags | VMSC_NOWAIT, hammer_sync_scan2, &info);
 1751 
 1752         if (info.error == 0 && (waitfor & MNT_WAIT)) {
 1753                 info.waitfor = waitfor;
 1754                 vsyncscan(hmp->mp, flags, hammer_sync_scan2, &info);
 1755         }
 1756         if (waitfor == MNT_WAIT) {
 1757                 hammer_flusher_sync(hmp);
 1758                 hammer_flusher_sync(hmp);
 1759         } else {
 1760                 hammer_flusher_async(hmp, NULL);
 1761                 hammer_flusher_async(hmp, NULL);
 1762         }
 1763         return(info.error);
 1764 }
 1765 
 1766 static int
 1767 hammer_sync_scan2(struct mount *mp, struct vnode *vp, void *data)
 1768 {
 1769         struct hammer_sync_info *info = data;
 1770         struct hammer_inode *ip;
 1771         int error;
 1772 
 1773         ip = VTOI(vp);
 1774         if (ip == NULL)
 1775                 return(0);
 1776         if (vp->v_type == VNON || vp->v_type == VBAD) {
 1777                 vclrisdirty(vp);
 1778                 return(0);
 1779         }
 1780         if ((ip->flags & HAMMER_INODE_MODMASK) == 0 &&
 1781             RB_EMPTY(&vp->v_rbdirty_tree)) {
 1782                 vclrisdirty(vp);
 1783                 return(0);
 1784         }
 1785         error = VOP_FSYNC(vp, MNT_NOWAIT, 0);
 1786         if (error)
 1787                 info->error = error;
 1788         return(0);
 1789 }

Cache object: ecee01cb75458808ec1259c7d924148e


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