sys/vfs/hammer2/hammer2_inode.c

   1 /*
   2  * Copyright (c) 2011-2013 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 #include <sys/cdefs.h>
  36 #include <sys/param.h>
  37 #include <sys/systm.h>
  38 #include <sys/types.h>
  39 #include <sys/lock.h>
  40 #include <sys/uuid.h>
  41
  42 #include "hammer2.h"
  43
  44 /*
  45  * Adding a ref to an inode is only legal if the inode already has at least
  46  * one ref.
  47  */
  48 void
  49 hammer2_inode_ref(hammer2_inode_t *ip)
  50 {
  51         atomic_add_int(&ip->refs, 1);
  52 }
  53
  54 /*
  55  * Drop an inode reference, freeing the inode when the last reference goes
  56  * away.
  57  */
  58 void
  59 hammer2_inode_drop(hammer2_inode_t *ip)
  60 {
  61         hammer2_mount_t *hmp;
  62         hammer2_inode_t *pip;
  63         hammer2_chain_t *chain;
  64         u_int refs;
  65
  66         for (;;) {
  67                 refs = ip->refs;
  68                 cpu_ccfence();
  69                 if (refs == 1) {
  70                         if (atomic_cmpset_int(&ip->refs, 1, 0)) {
  71                                 KKASSERT(ip->topo_cst.count == 0);
  72
  73                                 hmp = ip->hmp;
  74                                 ip->hmp = NULL;
  75                                 pip = ip->pip;
  76                                 ip->pip = NULL;
  77                                 chain = ip->chain;
  78                                 ip->chain = NULL;
  79                                 if (chain)
  80                                         hammer2_chain_drop(chain);
  81
  82                                 /*
  83                                  * We have to drop pip (if non-NULL) to
  84                                  * dispose of our implied reference from
  85                                  * ip->pip.  We can simply loop on it.
  86                                  */
  87                                 kfree(ip, hmp->minode);
  88                                 if (pip == NULL)
  89                                         break;
  90                                 ip = pip;
  91                                 /* continue */
  92                         }
  93                 } else {
  94                         if (atomic_cmpset_int(&ip->refs, refs, refs - 1))
  95                                 break;
  96                 }
  97         }
  98 }
  99
 100 /*
 101  * Get the vnode associated with the given inode, allocating the vnode if
 102  * necessary.  The vnode will be returned exclusively locked.
 103  *
 104  * The caller must lock the inode (shared or exclusive).
 105  *
 106  * Great care must be taken to avoid deadlocks and vnode acquisition/reclaim
 107  * races.
 108  */
 109 struct vnode *
 110 hammer2_igetv(hammer2_inode_t *ip, int *errorp)
 111 {
 112         hammer2_inode_data_t *ipdata;
 113         hammer2_pfsmount_t *pmp;
 114         struct vnode *vp;
 115         ccms_state_t ostate;
 116
 117         pmp = ip->pmp;
 118         KKASSERT(pmp != NULL);
 119         *errorp = 0;
 120         ipdata = &ip->chain->data->ipdata;
 121
 122         for (;;) {
 123                 /*
 124                  * Attempt to reuse an existing vnode assignment.  It is
 125                  * possible to race a reclaim so the vget() may fail.  The
 126                  * inode must be unlocked during the vget() to avoid a
 127                  * deadlock against a reclaim.
 128                  */
 129                 vp = ip->vp;
 130                 if (vp) {
 131                         /*
 132                          * Inode must be unlocked during the vget() to avoid
 133                          * possible deadlocks, but leave the ip ref intact.
 134                          *
 135                          * vnode is held to prevent destruction during the
 136                          * vget().  The vget() can still fail if we lost
 137                          * a reclaim race on the vnode.
 138                          */
 139                         vhold_interlocked(vp);
 140                         ostate = hammer2_inode_lock_temp_release(ip);
 141                         if (vget(vp, LK_EXCLUSIVE)) {
 142                                 vdrop(vp);
 143                                 hammer2_inode_lock_restore(ip, ostate);
 144                                 continue;
 145                         }
 146                         hammer2_inode_lock_restore(ip, ostate);
 147                         vdrop(vp);
 148                         /* vp still locked and ref from vget */
 149                         if (ip->vp != vp) {
 150                                 kprintf("hammer2: igetv race %p/%p\n",
 151                                         ip->vp, vp);
 152                                 vput(vp);
 153                                 continue;
 154                         }
 155                         *errorp = 0;
 156                         break;
 157                 }
 158
 159                 /*
 160                  * No vnode exists, allocate a new vnode.  Beware of
 161                  * allocation races.  This function will return an
 162                  * exclusively locked and referenced vnode.
 163                  */
 164                 *errorp = getnewvnode(VT_HAMMER2, pmp->mp, &vp, 0, 0);
 165                 if (*errorp) {
 166                         kprintf("hammer2: igetv getnewvnode failed %d\n",
 167                                 *errorp);
 168                         vp = NULL;
 169                         break;
 170                 }
 171
 172                 /*
 173                  * Lock the inode and check for an allocation race.
 174                  */
 175                 ostate = hammer2_inode_lock_upgrade(ip);
 176                 if (ip->vp != NULL) {
 177                         vp->v_type = VBAD;
 178                         vx_put(vp);
 179                         hammer2_inode_lock_restore(ip, ostate);
 180                         continue;
 181                 }
 182
 183                 switch (ipdata->type) {
 184                 case HAMMER2_OBJTYPE_DIRECTORY:
 185                         vp->v_type = VDIR;
 186                         break;
 187                 case HAMMER2_OBJTYPE_REGFILE:
 188                         vp->v_type = VREG;
 189                         vinitvmio(vp, ipdata->size,
 190                                   HAMMER2_LBUFSIZE,
 191                                   (int)ipdata->size & HAMMER2_LBUFMASK);
 192                         break;
 193                 case HAMMER2_OBJTYPE_SOFTLINK:
 194                         /*
 195                          * XXX for now we are using the generic file_read
 196                          * and file_write code so we need a buffer cache
 197                          * association.
 198                          */
 199                         vp->v_type = VLNK;
 200                         vinitvmio(vp, ipdata->size,
 201                                   HAMMER2_LBUFSIZE,
 202                                   (int)ipdata->size & HAMMER2_LBUFMASK);
 203                         break;
 204                 /* XXX FIFO */
 205                 default:
 206                         panic("hammer2: unhandled objtype %d", ipdata->type);
 207                         break;
 208                 }
 209
 210                 if (ip == pmp->iroot)
 211                         vsetflags(vp, VROOT);
 212
 213                 vp->v_data = ip;
 214                 ip->vp = vp;
 215                 hammer2_inode_ref(ip);          /* vp association */
 216                 hammer2_inode_lock_restore(ip, ostate);
 217                 break;
 218         }
 219
 220         /*
 221          * Return non-NULL vp and *errorp == 0, or NULL vp and *errorp != 0.
 222          */
 223         if (hammer2_debug & 0x0002) {
 224                 kprintf("igetv vp %p refs %d aux %d\n",
 225                         vp, vp->v_sysref.refcnt, vp->v_auxrefs);
 226         }
 227         return (vp);
 228 }
 229
 230 /*
 231  * The passed-in chain must be locked and the returned inode will also be
 232  * locked.  A ref is added to both the chain and the inode.
 233  *
 234  * The hammer2_inode structure regulates the interface between the high level
 235  * kernel VNOPS API and the filesystem backend (the chains).
 236  *
 237  * NOTE!     This routine allocates the hammer2_inode structure
 238  *           unconditionally, and thus there might be several which
 239  *           are associated with the same chain.  Particularly for hardlinks
 240  *           but this can also happen temporarily for normal files and
 241  *           directories.
 242  *
 243  * WARNING!  This routine sucks up the chain's lock (makes it part of the
 244  *           inode lock from the point of view of the inode lock API),
 245  *           so callers need to be careful.
 246  *
 247  * WARNING!  The mount code is allowed to pass dip == NULL for iroot and
 248  *           is allowed to pass pmp == NULL and dip == NULL for sroot.
 249  */
 250 hammer2_inode_t *
 251 hammer2_inode_get(hammer2_mount_t *hmp, hammer2_pfsmount_t *pmp,
 252                   hammer2_inode_t *dip, hammer2_chain_t *chain)
 253 {
 254         hammer2_inode_t *nip;
 255
 256         KKASSERT(chain->bref.type == HAMMER2_BREF_TYPE_INODE);
 257
 258         nip = kmalloc(sizeof(*nip), hmp->minode, M_WAITOK | M_ZERO);
 259
 260         nip->chain = chain;
 261         hammer2_chain_ref(chain);               /* nip->chain */
 262         nip->pip = dip;                         /* can be NULL */
 263         if (dip)
 264                 hammer2_inode_ref(dip); /* ref dip for nip->pip */
 265
 266         nip->pmp = pmp;
 267         nip->hmp = hmp;
 268
 269         /*
 270          * ref and lock on nip gives it state compatible to after a
 271          * hammer2_inode_lock_ex() call.
 272          */
 273         nip->refs = 1;
 274         ccms_cst_init(&nip->topo_cst, &nip->chain);
 275         ccms_thread_lock(&nip->topo_cst, CCMS_STATE_EXCLUSIVE);
 276         /* combination of thread lock and chain lock == inode lock */
 277
 278         return (nip);
 279 }
 280
 281 /*
 282  * Put away an inode, unlocking it and disconnecting it from its chain.
 283  *
 284  * The inode must be exclusively locked on call and non-recursed, with
 285  * at least 2 refs (one belonging to the exclusive lock, and one additional
 286  * ref belonging to the caller).
 287  *
 288  * Upon return the inode typically has one ref remaining which the caller
 289  * drops.
 290  */
 291 void
 292 hammer2_inode_put(hammer2_inode_t *ip)
 293 {
 294         hammer2_inode_t *pip;
 295         hammer2_chain_t *chain;
 296
 297         /*
 298          * Disconnect and unlock chain
 299          */
 300         KKASSERT(ip->refs >= 2);
 301         KKASSERT(ip->topo_cst.count == -1);     /* one excl lock allowed */
 302         if ((chain = ip->chain) != NULL) {
 303                 ip->chain = NULL;
 304                 hammer2_inode_unlock_ex(ip);
 305                 hammer2_chain_unlock(chain);    /* because ip->chain now NULL */
 306                 hammer2_chain_drop(chain);      /* from *_get() */
 307         }
 308
 309         /*
 310          * Disconnect pip
 311          */
 312         if ((pip = ip->pip) != NULL) {
 313                 ip->pip = NULL;
 314                 hammer2_inode_drop(pip);
 315         }
 316 }
 317
 318 /*
 319  * Create a new inode in the specified directory using the vattr to
 320  * figure out the type of inode.
 321  *
 322  * If no error occurs the new inode with its chain locked is returned in
 323  * *nipp, otherwise an error is returned and *nipp is set to NULL.
 324  *
 325  * If vap and/or cred are NULL the related fields are not set and the
 326  * inode type defaults to a directory.  This is used when creating PFSs
 327  * under the super-root, so the inode number is set to 1 in this case.
 328  *
 329  * dip is not locked on entry.
 330  */
 331 hammer2_inode_t *
 332 hammer2_inode_create(hammer2_trans_t *trans, hammer2_inode_t *dip,
 333                      struct vattr *vap, struct ucred *cred,
 334                      const uint8_t *name, size_t name_len,
 335                      int *errorp)
 336 {
 337         hammer2_inode_data_t *dipdata;
 338         hammer2_inode_data_t *nipdata;
 339         hammer2_mount_t *hmp;
 340         hammer2_chain_t *chain;
 341         hammer2_chain_t *parent;
 342         hammer2_inode_t *nip;
 343         hammer2_key_t lhc;
 344         int error;
 345         uid_t xuid;
 346         uuid_t dip_uid;
 347         uuid_t dip_gid;
 348         uint32_t dip_mode;
 349
 350         hmp = dip->hmp;
 351         lhc = hammer2_dirhash(name, name_len);
 352         *errorp = 0;
 353
 354         /*
 355          * Locate the inode or indirect block to create the new
 356          * entry in.  At the same time check for key collisions
 357          * and iterate until we don't get one.
 358          */
 359 retry:
 360         hammer2_inode_lock_ex(dip);
 361         dipdata = &dip->chain->data->ipdata;
 362         dip_uid = dipdata->uid;
 363         dip_gid = dipdata->gid;
 364         dip_mode = dipdata->mode;
 365
 366         parent = hammer2_chain_lookup_init(dip->chain, 0);
 367         error = 0;
 368         while (error == 0) {
 369                 chain = hammer2_chain_lookup(&parent, lhc, lhc, 0);
 370                 if (chain == NULL)
 371                         break;
 372                 if ((lhc & HAMMER2_DIRHASH_VISIBLE) == 0)
 373                         error = ENOSPC;
 374                 if ((lhc & HAMMER2_DIRHASH_LOMASK) == HAMMER2_DIRHASH_LOMASK)
 375                         error = ENOSPC;
 376                 hammer2_chain_unlock(chain);
 377                 chain = NULL;
 378                 ++lhc;
 379         }
 380         if (error == 0) {
 381                 error = hammer2_chain_create(trans, parent, &chain,
 382                                              lhc, 0,
 383                                              HAMMER2_BREF_TYPE_INODE,
 384                                              HAMMER2_INODE_BYTES);
 385         }
 386
 387         /*
 388          * Cleanup and handle retries.
 389          */
 390         if (error == EAGAIN) {
 391                 hammer2_chain_ref(parent);
 392                 hammer2_chain_lookup_done(parent);
 393                 hammer2_inode_unlock_ex(dip);
 394                 hammer2_chain_wait(parent);
 395                 hammer2_chain_drop(parent);
 396                 goto retry;
 397         }
 398         hammer2_chain_lookup_done(parent);
 399         hammer2_inode_unlock_ex(dip);
 400
 401         if (error) {
 402                 KKASSERT(chain == NULL);
 403                 *errorp = error;
 404                 return (NULL);
 405         }
 406
 407         /*
 408          * Set up the new inode.
 409          *
 410          * NOTE: *_get() integrates chain's lock into the inode lock.
 411          *
 412          * NOTE: Only one new inode can currently be created per
 413          *       transaction.  If the need arises we can adjust
 414          *       hammer2_trans_init() to allow more.
 415          */
 416         nip = hammer2_inode_get(dip->hmp, dip->pmp, dip, chain);
 417         nipdata = &chain->data->ipdata;
 418
 419         if (vap) {
 420                 KKASSERT(trans->inodes_created == 0);
 421                 nipdata->type = hammer2_get_obj_type(vap->va_type);
 422                 nipdata->inum = trans->sync_tid;
 423                 ++trans->inodes_created;
 424         } else {
 425                 nipdata->type = HAMMER2_OBJTYPE_DIRECTORY;
 426                 nipdata->inum = 1;
 427         }
 428         nipdata->version = HAMMER2_INODE_VERSION_ONE;
 429         hammer2_update_time(&nipdata->ctime);
 430         nipdata->mtime = nipdata->ctime;
 431         if (vap)
 432                 nipdata->mode = vap->va_mode;
 433         nipdata->nlinks = 1;
 434         if (vap) {
 435                 if (dip) {
 436                         xuid = hammer2_to_unix_xid(&dip_uid);
 437                         xuid = vop_helper_create_uid(dip->pmp->mp,
 438                                                      dip_mode,
 439                                                      xuid,
 440                                                      cred,
 441                                                      &vap->va_mode);
 442                 } else {
 443                         xuid = 0;
 444                 }
 445                 if (vap->va_vaflags & VA_UID_UUID_VALID)
 446                         nipdata->uid = vap->va_uid_uuid;
 447                 else if (vap->va_uid != (uid_t)VNOVAL)
 448                         hammer2_guid_to_uuid(&nipdata->uid, vap->va_uid);
 449                 else
 450                         hammer2_guid_to_uuid(&nipdata->uid, xuid);
 451
 452                 if (vap->va_vaflags & VA_GID_UUID_VALID)
 453                         nipdata->gid = vap->va_gid_uuid;
 454                 else if (vap->va_gid != (gid_t)VNOVAL)
 455                         hammer2_guid_to_uuid(&nipdata->gid, vap->va_gid);
 456                 else if (dip)
 457                         nipdata->gid = dip_gid;
 458         }
 459
 460         /*
 461          * Regular files and softlinks allow a small amount of data to be
 462          * directly embedded in the inode.  This flag will be cleared if
 463          * the size is extended past the embedded limit.
 464          */
 465         if (nipdata->type == HAMMER2_OBJTYPE_REGFILE ||
 466             nipdata->type == HAMMER2_OBJTYPE_SOFTLINK) {
 467                 nipdata->op_flags |= HAMMER2_OPFLAG_DIRECTDATA;
 468         }
 469
 470         KKASSERT(name_len < HAMMER2_INODE_MAXNAME);
 471         bcopy(name, nipdata->filename, name_len);
 472         nipdata->name_key = lhc;
 473         nipdata->name_len = name_len;
 474
 475         return (nip);
 476 }
 477
 478 /*
 479  * Create a duplicate of (ochain) in the specified target directory (dip).
 480  * ochain must represent an inode.  The new chain is returned locked and
 481  * referenced.
 482  */
 483 hammer2_chain_t *
 484 hammer2_inode_duplicate(hammer2_trans_t *trans, hammer2_chain_t *ochain,
 485                         hammer2_inode_t *dip, int *errorp)
 486 {
 487         hammer2_inode_data_t *nipdata;
 488         hammer2_mount_t *hmp;
 489         hammer2_chain_t *parent;
 490         hammer2_chain_t *chain;
 491         hammer2_key_t lhc;
 492
 493         *errorp = 0;
 494         hmp = dip->hmp;
 495         lhc = ochain->data->ipdata.inum;
 496         KKASSERT((lhc & HAMMER2_DIRHASH_VISIBLE) == 0);
 497
 498         /*
 499          * Locate the inode or indirect block to create the new
 500          * entry in.
 501          *
 502          * There should be no key collisions with invisible inode keys.
 503          */
 504 retry:
 505         parent = hammer2_chain_lookup_init(dip->chain, 0);
 506         chain = hammer2_chain_lookup(&parent, lhc, lhc, 0);
 507         if (chain) {
 508                 hammer2_chain_unlock(chain);
 509                 chain = NULL;
 510                 *errorp = ENOSPC;
 511         }
 512
 513         /*
 514          * Create entry in common parent directory.
 515          */
 516         if (*errorp == 0) {
 517                 *errorp = hammer2_chain_create(trans, parent, &chain,
 518                                                lhc, 0,
 519                                                HAMMER2_BREF_TYPE_INODE,/* n/a */
 520                                                HAMMER2_INODE_BYTES);   /* n/a */
 521         }
 522
 523         /*
 524          * Cleanup and handle retries.
 525          */
 526         if (*errorp == EAGAIN) {
 527                 hammer2_chain_ref(parent);
 528                 hammer2_chain_lookup_done(parent);
 529                 hammer2_chain_wait(parent);
 530                 hammer2_chain_drop(parent);
 531                 goto retry;
 532         }
 533
 534         hammer2_chain_lookup_done(parent);
 535
 536         /*
 537          * Handle the error case
 538          */
 539         if (*errorp) {
 540                 KKASSERT(chain == NULL);
 541                 return (NULL);
 542         }
 543
 544         /*
 545          * XXX This is currently a horrible hack.  Well, if we wanted to
 546          *     duplicate a file, i.e. as in a snapshot, we definitely
 547          *     would have to flush it first.
 548          *
 549          *     For hardlink target generation we can theoretically move any
 550          *     active chain structures without flushing, but that gets really
 551          *     iffy for code which follows chain->parent and ip->pip links.
 552          *
 553          * XXX only works with files.  Duplicating a directory hierarchy
 554          *     requires a flush but doesn't deal with races post-flush.
 555          *     Well, it would work I guess, but you might catch some files
 556          *     mid-operation.
 557          *
 558          * We cannot leave ochain with any in-memory chains because (for a
 559          * hardlink), ochain will become a OBJTYPE_HARDLINK which is just a
 560          * pointer to the real hardlink's inum and can't have any sub-chains.
 561          * XXX might be 0-ref chains left.
 562          */
 563         hammer2_chain_flush(trans, ochain);
 564         /*KKASSERT(RB_EMPTY(&ochain.rbhead));*/
 565
 566         hammer2_chain_modify(trans, chain, 0);
 567         nipdata = &chain->data->ipdata;
 568         *nipdata = ochain->data->ipdata;
 569
 570         /*
 571          * Directory entries are inodes but this is a hidden hardlink
 572          * target.  The name isn't used but to ease debugging give it
 573          * a name after its inode number.
 574          */
 575         ksnprintf(nipdata->filename, sizeof(nipdata->filename),
 576                   "0x%016jx", (intmax_t)nipdata->inum);
 577         nipdata->name_len = strlen(nipdata->filename);
 578         nipdata->name_key = lhc;
 579
 580         return (chain);
 581 }
 582
 583 /*
 584  * Connect the target inode to the media topology at (dip, name, len).
 585  * This function creates a directory entry and replace (*chainp).
 586  *
 587  * The caller usually holds the related inode exclusive locked through this
 588  * call and is also responsible for replacing ip->chain after we return.
 589  *
 590  * If (*chainp) was marked DELETED then it represents a terminus inode
 591  * with no other nlinks, we can simply duplicate the chain (in-memory
 592  * chain structures cannot be moved within the in-memory topology, only
 593  * duplicated, but the duplicate uses the same bref).
 594  *
 595  * if (*chainp) is not marked DELETED then it represents a hardlink
 596  * terminus which still has a non-zero nlink count.  Instead of duplicating
 597  * it (which would be like a snapshot), we need to create a
 598  * OBJTYPE_HARDLINK directory entry which references (*chainp)'s inode
 599  * number and bump (*chainp)'s nlinks.  In this situation we return
 600  * the terminus as *chainp.
 601  *
 602  * (*chainp) is adjusted if necessary and returned locked.  If different,
 603  * the original (*chainp) is unlocked.  Note that the (*chainp) that is
 604  * returned is always the hardlink terminus (the actual inode), which
 605  * might reside in some parent directory.  It will not be the
 606  * OBJTYPE_HARDLINK pointer.
 607  *
 608  * WARNING!  The caller is likely holding ip/ip->chain locked exclusively.
 609  *           Replacing ip->chain here would create confusion so we leave
 610  *           it to the caller to do that.
 611  *
 612  *           (The caller is expected to hold the related inode exclusively)
 613  */
 614 int
 615 hammer2_inode_connect(hammer2_trans_t *trans, hammer2_inode_t *dip,
 616                       hammer2_chain_t **chainp,
 617                       const uint8_t *name, size_t name_len)
 618 {
 619         hammer2_inode_data_t *ipdata;
 620         hammer2_mount_t *hmp;
 621         hammer2_chain_t *nchain;
 622         hammer2_chain_t *parent;
 623         hammer2_chain_t *ochain;
 624         hammer2_key_t lhc;
 625         int error;
 626         int hlink;
 627
 628         hmp = dip->hmp;
 629
 630         ochain = *chainp;
 631
 632         /*
 633          * Since ochain is either disconnected from the topology or represents
 634          * a hardlink terminus which is always a parent of or equal to dip,
 635          * we should be able to safely lock dip->chain for our setup.
 636          */
 637         parent = hammer2_chain_lookup_init(dip->chain, 0);
 638
 639         lhc = hammer2_dirhash(name, name_len);
 640         hlink = ((ochain->flags & HAMMER2_CHAIN_DELETED) == 0);
 641         kprintf("reconnect hlink=%d name=%*.*s\n",
 642                 hlink, (int)name_len, (int)name_len, name);
 643
 644         /*
 645          * In fake mode flush oip so we can just snapshot it downbelow.
 646          * A flush is not otherwise needed as the new chain inherits
 647          * all active children of the old chain (they will share the same
 648          * chain_core).
 649          */
 650         if (hlink && hammer2_hardlink_enable < 0)
 651                 hammer2_chain_flush(trans, ochain);
 652
 653         /*
 654          * Locate the inode or indirect block to create the new
 655          * entry in.  At the same time check for key collisions
 656          * and iterate until we don't get one.
 657          */
 658         error = 0;
 659         while (error == 0) {
 660                 nchain = hammer2_chain_lookup(&parent, lhc, lhc, 0);
 661                 if (nchain == NULL)
 662                         break;
 663                 if ((lhc & HAMMER2_DIRHASH_LOMASK) == HAMMER2_DIRHASH_LOMASK)
 664                         error = ENOSPC;
 665                 hammer2_chain_unlock(nchain);
 666                 nchain = NULL;
 667                 ++lhc;
 668         }
 669
 670         /*
 671          * Passing a non-NULL chain to hammer2_chain_create() reconnects the
 672          * existing chain instead of creating a new one.  The chain's bref
 673          * will be properly updated.
 674          */
 675         if (error == 0) {
 676                 if (hlink) {
 677                         /*
 678                          * Hardlink pointer needed, create totally fresh
 679                          * directory entry.
 680                          */
 681                         KKASSERT(nchain == NULL);
 682                         error = hammer2_chain_create(trans, parent, &nchain,
 683                                                      lhc, 0,
 684                                                      HAMMER2_BREF_TYPE_INODE,
 685                                                      HAMMER2_INODE_BYTES);
 686                 } else {
 687                         /*
 688                          * Original inode reconnected, duplicate as a
 689                          * new directory entry, leave unconnected and
 690                          * then call chain_create() to connect it.
 691                          */
 692                         nchain = ochain;
 693                         ochain = NULL;
 694                         hammer2_chain_duplicate(trans, NULL, -1, &nchain);
 695                         error = hammer2_chain_create(trans, parent, &nchain,
 696                                                      lhc, 0,
 697                                                      HAMMER2_BREF_TYPE_INODE,
 698                                                      HAMMER2_INODE_BYTES);
 699                 }
 700         }
 701
 702         /*
 703          * Unlock stuff.
 704          */
 705         KKASSERT(error != EAGAIN);
 706         hammer2_chain_lookup_done(parent);
 707         parent = NULL;
 708
 709         /*
 710          * nchain should be NULL on error, leave ochain (== *chainp) alone.
 711          */
 712         if (error) {
 713                 KKASSERT(nchain == NULL);
 714                 return (error);
 715         }
 716
 717         /*
 718          * Directory entries are inodes so if the name has changed we have
 719          * to update the inode.
 720          *
 721          * When creating an OBJTYPE_HARDLINK entry remember to unlock the
 722          * chain, the caller will access the hardlink via the actual hardlink
 723          * target file and not the hardlink pointer entry, so we must still
 724          * return ochain.
 725          */
 726         if (hlink && hammer2_hardlink_enable >= 0) {
 727                 /*
 728                  * Create the HARDLINK pointer.  oip represents the hardlink
 729                  * target in this situation.
 730                  *
 731                  * We will return ochain (the hardlink target).
 732                  */
 733                 hammer2_chain_modify(trans, nchain, 0);
 734                 KKASSERT(name_len < HAMMER2_INODE_MAXNAME);
 735                 ipdata = &nchain->data->ipdata;
 736                 bcopy(name, ipdata->filename, name_len);
 737                 ipdata->name_key = lhc;
 738                 ipdata->name_len = name_len;
 739                 ipdata->target_type = ochain->data->ipdata.type;
 740                 ipdata->type = HAMMER2_OBJTYPE_HARDLINK;
 741                 ipdata->inum = ochain->data->ipdata.inum;
 742                 ipdata->nlinks = 1;
 743                 kprintf("created hardlink %*.*s\n",
 744                         (int)name_len, (int)name_len, name);
 745                 hammer2_chain_unlock(nchain);
 746                 nchain = ochain;
 747                 ochain = NULL;
 748         } else if (hlink && hammer2_hardlink_enable < 0) {
 749                 /*
 750                  * Create a snapshot (hardlink fake mode for debugging).
 751                  * (ochain already flushed above so we can just copy the
 752                  * bref XXX).
 753                  *
 754                  * Since this is a snapshot we return nchain in the fake
 755                  * hardlink case.
 756                  */
 757                 hammer2_chain_modify(trans, nchain, 0);
 758                 KKASSERT(name_len < HAMMER2_INODE_MAXNAME);
 759                 ipdata = &nchain->data->ipdata;
 760                 *ipdata = ochain->data->ipdata;
 761                 bcopy(name, ipdata->filename, name_len);
 762                 ipdata->name_key = lhc;
 763                 ipdata->name_len = name_len;
 764                 kprintf("created fake hardlink %*.*s\n",
 765                         (int)name_len, (int)name_len, name);
 766         } else {
 767                 /*
 768                  * We are reconnecting a previously DELETED node in a new
 769                  * location.  nchain is a duplication of the deleted node.
 770                  *
 771                  * We must fixup the name stored in oip.
 772                  */
 773                 hammer2_chain_modify(trans, nchain, 0);
 774                 ipdata = &nchain->data->ipdata;
 775
 776                 if (ipdata->name_len != name_len ||
 777                     bcmp(ipdata->filename, name, name_len) != 0) {
 778                         KKASSERT(name_len < HAMMER2_INODE_MAXNAME);
 779                         bcopy(name, ipdata->filename, name_len);
 780                         ipdata->name_key = lhc;
 781                         ipdata->name_len = name_len;
 782                 }
 783                 ipdata->nlinks = 1;
 784         }
 785
 786         /*
 787          * We are replacing ochain with nchain, unlock ochain.  In the
 788          * case where ochain is left unchanged the code above sets
 789          * nchain to ochain and ochain to NULL, resulting in a NOP here.
 790          */
 791         if (ochain)
 792                 hammer2_chain_unlock(ochain);
 793         *chainp = nchain;
 794
 795         return (0);
 796 }
 797
 798 /*
 799  * Caller must hold exactly ONE exclusive lock on the inode.  *nchainp
 800  * must be exclusive locked (its own exclusive lock even if it is the
 801  * same as ip->chain).
 802  *
 803  * This function replaces ip->chain.  The exclusive lock on the passed
 804  * nchain is inherited by the inode and the caller becomes responsible
 805  * for unlocking it when the caller unlocks the inode.
 806  *
 807  * ochain was locked by the caller indirectly via the inode lock.  Since
 808  * ip->chain is being repointed, we become responsible for cleaning up
 809  * that lock.
 810  *
 811  * Return *nchainp = NULL as a safety.
 812  */
 813 void
 814 hammer2_inode_repoint(hammer2_inode_t *ip, hammer2_chain_t **nchainp)
 815 {
 816         hammer2_chain_t *nchain = *nchainp;
 817         hammer2_chain_t *ochain;
 818
 819         /*
 820          * Repoint ip->chain if necessary.
 821          *
 822          * (Inode must be locked exclusively by parent)
 823          */
 824         ochain = ip->chain;
 825         if (ochain != nchain) {
 826                 hammer2_chain_ref(nchain);              /* for ip->chain */
 827                 ip->chain = nchain;
 828                 if (ochain) {
 829                         hammer2_chain_unlock(ochain);
 830                         hammer2_chain_drop(ochain);     /* for ip->chain */
 831                 }
 832         } else {
 833                 hammer2_chain_unlock(nchain);
 834         }
 835         *nchainp = NULL;
 836 }
 837
 838 /*
 839  * Unlink the file from the specified directory inode.  The directory inode
 840  * does not need to be locked.  The caller should pass a non-NULL (ip)
 841  * representing the object being removed only if the related vnode is
 842  * potentially inactive (not referenced in the caller's active path),
 843  * so we can vref/vrele it to trigger the VOP_INACTIVE path and properly
 844  * recycle it.
 845  *
 846  * isdir determines whether a directory/non-directory check should be made.
 847  * No check is made if isdir is set to -1.
 848  *
 849  * NOTE!  This function does not prevent the underlying file from still
 850  *        being used if it has other refs (such as from an inode, or if it's
 851  *        chain is manually held).  However, the caller is responsible for
 852  *        fixing up ip->chain if e.g. a rename occurs (see chain_duplicate()).
 853  */
 854 int
 855 hammer2_unlink_file(hammer2_trans_t *trans, hammer2_inode_t *dip,
 856                     const uint8_t *name, size_t name_len, int isdir)
 857 {
 858         hammer2_inode_data_t *ipdata;
 859         hammer2_mount_t *hmp;
 860         hammer2_chain_t *parent;
 861         hammer2_chain_t *ochain;
 862         hammer2_chain_t *chain;
 863         hammer2_chain_t *dparent;
 864         hammer2_chain_t *dchain;
 865         hammer2_key_t lhc;
 866         int error;
 867         int parent_ref;
 868         uint8_t type;
 869
 870         parent_ref = 0;
 871         error = 0;
 872         ochain = NULL;
 873         hmp = dip->hmp;
 874         lhc = hammer2_dirhash(name, name_len);
 875
 876         /*
 877          * Search for the filename in the directory
 878          */
 879         hammer2_inode_lock_ex(dip);
 880
 881         parent = hammer2_chain_lookup_init(dip->chain, 0);
 882         chain = hammer2_chain_lookup(&parent,
 883                                      lhc, lhc + HAMMER2_DIRHASH_LOMASK,
 884                                      0);
 885         while (chain) {
 886                 if (chain->bref.type == HAMMER2_BREF_TYPE_INODE &&
 887                     name_len == chain->data->ipdata.name_len &&
 888                     bcmp(name, chain->data->ipdata.filename, name_len) == 0) {
 889                         break;
 890                 }
 891                 chain = hammer2_chain_next(&parent, chain,
 892                                            lhc, lhc + HAMMER2_DIRHASH_LOMASK,
 893                                            0);
 894         }
 895         hammer2_inode_unlock_ex(dip);   /* retain parent */
 896
 897         /*
 898          * Not found or wrong type (isdir < 0 disables the type check).
 899          * If a hardlink pointer, type checks use the hardlink target.
 900          */
 901         if (chain == NULL) {
 902                 error = ENOENT;
 903                 goto done;
 904         }
 905         if ((type = chain->data->ipdata.type) == HAMMER2_OBJTYPE_HARDLINK)
 906                 type = chain->data->ipdata.target_type;
 907
 908         if (type == HAMMER2_OBJTYPE_DIRECTORY && isdir == 0) {
 909                 error = ENOTDIR;
 910                 goto done;
 911         }
 912         if (type != HAMMER2_OBJTYPE_DIRECTORY && isdir == 1) {
 913                 error = EISDIR;
 914                 goto done;
 915         }
 916
 917         /*
 918          * Hardlink must be resolved.  We can't hold parent locked while we
 919          * do this or we could deadlock.
 920          *
 921          * On success chain will be adjusted to point at the hardlink target
 922          * and ochain will point to the hardlink pointer in the original
 923          * directory.  Otherwise chain remains pointing to the original.
 924          */
 925         if (chain->data->ipdata.type == HAMMER2_OBJTYPE_HARDLINK) {
 926                 KKASSERT(parent_ref == 0);
 927                 hammer2_chain_unlock(parent);
 928                 parent = NULL;
 929                 error = hammer2_hardlink_find(dip, &chain, &ochain);
 930         }
 931
 932         /*
 933          * If this is a directory the directory must be empty.  However, if
 934          * isdir < 0 we are doing a rename and the directory does not have
 935          * to be empty.
 936          *
 937          * NOTE: We check the full key range here which covers both visible
 938          *       and invisible entries.  Theoretically there should be no
 939          *       invisible (hardlink target) entries if there are no visible
 940          *       entries.
 941          */
 942         if (type == HAMMER2_OBJTYPE_DIRECTORY && isdir >= 0) {
 943                 dparent = hammer2_chain_lookup_init(chain, 0);
 944                 dchain = hammer2_chain_lookup(&dparent,
 945                                               0, (hammer2_key_t)-1,
 946                                               HAMMER2_LOOKUP_NODATA);
 947                 if (dchain) {
 948                         hammer2_chain_unlock(dchain);
 949                         hammer2_chain_lookup_done(dparent);
 950                         error = ENOTEMPTY;
 951                         goto done;
 952                 }
 953                 hammer2_chain_lookup_done(dparent);
 954                 dparent = NULL;
 955                 /* dchain NULL */
 956         }
 957
 958         /*
 959          * Ok, we can now unlink the chain.  We always decrement nlinks even
 960          * if the entry can be deleted in case someone has the file open and
 961          * does an fstat().
 962          *
 963          * The chain itself will no longer be in the on-media topology but
 964          * can still be flushed to the media (e.g. if an open descriptor
 965          * remains).  When the last vnode/ip ref goes away the chain will
 966          * be marked unmodified, avoiding any further (now unnecesary) I/O.
 967          *
 968          * A non-NULL ochain indicates a hardlink.
 969          */
 970         if (ochain) {
 971                 /*
 972                  * Delete the original hardlink pointer.
 973                  *
 974                  * NOTE: parent from above is NULL when ochain != NULL
 975                  *       so we can reuse it.
 976                  */
 977                 hammer2_chain_lock(ochain, HAMMER2_RESOLVE_ALWAYS);
 978                 parent_ref = 1;
 979                 for (;;) {
 980                         parent = ochain->parent;
 981                         hammer2_chain_ref(parent);
 982                         hammer2_chain_unlock(ochain);
 983                         hammer2_chain_lock(parent, HAMMER2_RESOLVE_ALWAYS);
 984                         hammer2_chain_lock(ochain, HAMMER2_RESOLVE_ALWAYS);
 985                         if (ochain->parent == parent)
 986                                 break;
 987                         hammer2_chain_unlock(parent);
 988                         hammer2_chain_drop(parent);
 989                 }
 990
 991                 hammer2_chain_delete(trans, parent, ochain);
 992                 hammer2_chain_unlock(ochain);
 993                 hammer2_chain_unlock(parent);
 994                 hammer2_chain_drop(parent);
 995                 parent = NULL;
 996
 997                 /*
 998                  * Then decrement nlinks on hardlink target, deleting
 999                  * the target when nlinks drops to 0.
1000                  */
1001                 if (chain->data->ipdata.nlinks == 1) {
1002                         dparent = chain->parent;
1003                         hammer2_chain_ref(chain);
1004                         hammer2_chain_unlock(chain);
1005                         hammer2_chain_lock(dparent, HAMMER2_RESOLVE_ALWAYS);
1006                         hammer2_chain_lock(chain, HAMMER2_RESOLVE_ALWAYS);
1007                         hammer2_chain_drop(chain);
1008                         hammer2_chain_modify(trans, chain, 0);
1009                         --chain->data->ipdata.nlinks;
1010                         hammer2_chain_delete(trans, dparent, chain);
1011                         hammer2_chain_unlock(dparent);
1012                 } else {
1013                         hammer2_chain_modify(trans, chain, 0);
1014                         --chain->data->ipdata.nlinks;
1015                 }
1016         } else {
1017                 /*
1018                  * Otherwise this was not a hardlink and we can just
1019                  * remove the entry and decrement nlinks.
1020                  *
1021                  * NOTE: *_get() integrates chain's lock into the inode lock.
1022                  */
1023                 ipdata = &chain->data->ipdata;
1024                 hammer2_chain_modify(trans, chain, 0);
1025                 --ipdata->nlinks;
1026                 hammer2_chain_delete(trans, parent, chain);
1027         }
1028
1029         error = 0;
1030 done:
1031         if (chain)
1032                 hammer2_chain_unlock(chain);
1033         if (parent) {
1034                 hammer2_chain_lookup_done(parent);
1035                 if (parent_ref)
1036                         hammer2_chain_drop(parent);
1037         }
1038         if (ochain)
1039                 hammer2_chain_drop(ochain);
1040
1041         return error;
1042 }
1043
1044 /*
1045  * Calculate the allocation size for the file fragment straddling EOF
1046  */
1047 int
1048 hammer2_inode_calc_alloc(hammer2_key_t filesize)
1049 {
1050         int frag = (int)filesize & HAMMER2_PBUFMASK;
1051         int radix;
1052
1053         if (frag == 0)
1054                 return(0);
1055         for (radix = HAMMER2_MINALLOCRADIX; frag > (1 << radix); ++radix)
1056                 ;
1057         return (radix);
1058 }
1059
1060 /*
1061  * Given an exclusively locked inode we consolidate its chain for hardlink
1062  * creation, adding (nlinks) to the file's link count and potentially
1063  * relocating the file to a directory common to ip->pip and tdip.
1064  *
1065  * Returns a locked chain in (*chainp) (the chain's lock is in addition to
1066  * any lock it might already have due to the inode being locked).  *chainp
1067  * is set unconditionally and its previous contents can be garbage.
1068  *
1069  * The caller is responsible for replacing ip->chain, not us.  For certain
1070  * operations such as renames the caller may do additional manipulation
1071  * of the chain before replacing ip->chain.
1072  */
1073 int
1074 hammer2_hardlink_consolidate(hammer2_trans_t *trans, hammer2_inode_t *ip,
1075                              hammer2_chain_t **chainp,
1076                              hammer2_inode_t *tdip, int nlinks)
1077 {
1078         hammer2_inode_data_t *ipdata;
1079         hammer2_mount_t *hmp;
1080         hammer2_inode_t *fdip;
1081         hammer2_inode_t *cdip;
1082         hammer2_chain_t *chain;
1083         hammer2_chain_t *nchain;
1084         hammer2_chain_t *parent;
1085         int error;
1086
1087         /*
1088          * Extra lock on chain so it can be returned locked.
1089          */
1090         hmp = tdip->hmp;
1091
1092         chain = ip->chain;
1093         error = hammer2_chain_lock(chain, HAMMER2_RESOLVE_ALWAYS);
1094         KKASSERT(error == 0);
1095
1096         if (nlinks == 0 &&                      /* no hardlink needed */
1097             (chain->data->ipdata.name_key & HAMMER2_DIRHASH_VISIBLE)) {
1098                 *chainp = chain;
1099                 return (0);
1100         }
1101         if (hammer2_hardlink_enable < 0) {      /* fake hardlinks */
1102                 *chainp = chain;
1103                 return (0);
1104         }
1105
1106         if (hammer2_hardlink_enable == 0) {     /* disallow hardlinks */
1107                 hammer2_chain_unlock(chain);
1108                 *chainp = NULL;
1109                 return (ENOTSUP);
1110         }
1111
1112         /*
1113          * cdip will be returned with a ref, but not locked.
1114          */
1115         fdip = ip->pip;
1116         cdip = hammer2_inode_common_parent(fdip, tdip);
1117
1118         /*
1119          * If no change in the hardlink's target directory is required and
1120          * this is already a hardlink target, all we need to do is adjust
1121          * the link count.
1122          */
1123         if (cdip == fdip &&
1124             (chain->data->ipdata.name_key & HAMMER2_DIRHASH_VISIBLE) == 0) {
1125                 if (nlinks) {
1126                         hammer2_chain_modify(trans, chain, 0);
1127                         chain->data->ipdata.nlinks += nlinks;
1128                 }
1129                 *chainp = chain;
1130                 error = 0;
1131                 goto done;
1132         }
1133
1134         /*
1135          * We either have to move an existing hardlink target or we have
1136          * to create a fresh hardlink target.
1137          *
1138          * Hardlink targets are hidden inodes in a parent directory common
1139          * to all directory entries referencing the hardlink.
1140          */
1141         nchain = hammer2_inode_duplicate(trans, chain, cdip, &error);
1142         if (error == 0) {
1143                 /*
1144                  * Bump nlinks on duplicated hidden inode.
1145                  */
1146                 hammer2_chain_modify(trans, nchain, 0);
1147                 nchain->data->ipdata.nlinks += nlinks;
1148
1149                 /*
1150                  * If the old chain is not a hardlink target then replace
1151                  * it with a OBJTYPE_HARDLINK pointer.
1152                  *
1153                  * If the old chain IS a hardlink target then delete it.
1154                  */
1155                 if (chain->data->ipdata.name_key & HAMMER2_DIRHASH_VISIBLE) {
1156                         hammer2_chain_modify(trans, chain, 0);
1157                         ipdata = &chain->data->ipdata;
1158                         ipdata->target_type = ipdata->type;
1159                         ipdata->type = HAMMER2_OBJTYPE_HARDLINK;
1160                         ipdata->uflags = 0;
1161                         ipdata->rmajor = 0;
1162                         ipdata->rminor = 0;
1163                         ipdata->ctime = 0;
1164                         ipdata->mtime = 0;
1165                         ipdata->atime = 0;
1166                         ipdata->btime = 0;
1167                         bzero(&ipdata->uid, sizeof(ipdata->uid));
1168                         bzero(&ipdata->gid, sizeof(ipdata->gid));
1169                         ipdata->op_flags = HAMMER2_OPFLAG_DIRECTDATA;
1170                         ipdata->cap_flags = 0;
1171                         ipdata->mode = 0;
1172                         ipdata->size = 0;
1173                         ipdata->nlinks = 1;
1174                         ipdata->iparent = 0;    /* XXX */
1175                         ipdata->pfs_type = 0;
1176                         ipdata->pfs_inum = 0;
1177                         bzero(&ipdata->pfs_clid, sizeof(ipdata->pfs_clid));
1178                         bzero(&ipdata->pfs_fsid, sizeof(ipdata->pfs_fsid));
1179                         ipdata->data_quota = 0;
1180                         ipdata->data_count = 0;
1181                         ipdata->inode_quota = 0;
1182                         ipdata->inode_count = 0;
1183                         ipdata->attr_tid = 0;
1184                         ipdata->dirent_tid = 0;
1185                         bzero(&ipdata->u, sizeof(ipdata->u));
1186                         /* XXX transaction ids */
1187                 } else {
1188                         kprintf("DELETE INVISIBLE\n");
1189                         for (;;) {
1190                                 parent = chain->parent;
1191                                 hammer2_chain_ref(parent);
1192                                 hammer2_chain_ref(chain);
1193                                 hammer2_chain_unlock(chain);
1194                                 hammer2_chain_lock(parent,
1195                                                    HAMMER2_RESOLVE_ALWAYS);
1196                                 hammer2_chain_lock(chain,
1197                                                    HAMMER2_RESOLVE_ALWAYS);
1198                                 hammer2_chain_drop(chain);
1199                                 if (chain->parent == parent)
1200                                         break;
1201                                 hammer2_chain_unlock(parent);
1202                                 hammer2_chain_drop(parent);
1203                         }
1204                         hammer2_chain_delete(trans, parent, chain);
1205                         hammer2_chain_unlock(parent);
1206                         hammer2_chain_drop(parent);
1207                 }
1208
1209                 /*
1210                  * Return the new chain.
1211                  */
1212                 hammer2_chain_unlock(chain);
1213                 *chainp = nchain;
1214         } else {
1215                 /*
1216                  * Return an error
1217                  */
1218                 hammer2_chain_unlock(chain);
1219                 *chainp = NULL;
1220         }
1221
1222         /*
1223          * Cleanup, chain/nchain already dealt with.
1224          */
1225 done:
1226         hammer2_inode_drop(cdip);
1227
1228         return (error);
1229 }
1230
1231 /*
1232  * If (*ochainp) is non-NULL it points to the forward OBJTYPE_HARDLINK
1233  * inode while (*chainp) points to the resolved (hidden hardlink
1234  * target) inode.  In this situation when nlinks is 1 we wish to
1235  * deconsolidate the hardlink, moving it back to the directory that now
1236  * represents the only remaining link.
1237  */
1238 int
1239 hammer2_hardlink_deconsolidate(hammer2_trans_t *trans,
1240                                hammer2_inode_t *dip,
1241                                hammer2_chain_t **chainp,
1242                                hammer2_chain_t **ochainp)
1243 {
1244         if (*ochainp == NULL)
1245                 return (0);
1246         /* XXX */
1247         return (0);
1248 }
1249
1250 /*
1251  * The caller presents a locked *chainp pointing to a HAMMER2_BREF_TYPE_INODE
1252  * with an obj_type of HAMMER2_OBJTYPE_HARDLINK.  This routine will gobble
1253  * the *chainp and return a new locked *chainp representing the file target
1254  * (the original *chainp will be unlocked).
1255  *
1256  * When a match is found the chain representing the original HARDLINK
1257  * will be returned in *ochainp with a ref, but not locked.
1258  *
1259  * When no match is found *chainp is set to NULL and EIO is returned.
1260  * (*ochainp) will still be set to the original chain with a ref but not
1261  * locked.
1262  */
1263 int
1264 hammer2_hardlink_find(hammer2_inode_t *dip, hammer2_chain_t **chainp,
1265                       hammer2_chain_t **ochainp)
1266 {
1267         hammer2_chain_t *chain = *chainp;
1268         hammer2_chain_t *parent;
1269         hammer2_inode_t *ip;
1270         hammer2_inode_t *pip;
1271         hammer2_key_t lhc;
1272
1273         pip = dip;
1274         hammer2_inode_ref(pip);         /* for loop */
1275         hammer2_chain_ref(chain);       /* for (*ochainp) */
1276
1277         *ochainp = chain;
1278
1279         /*
1280          * Locate the hardlink.  pip is referenced and not locked,
1281          * ipp.
1282          *
1283          * chain is reused.
1284          */
1285         lhc = chain->data->ipdata.inum;
1286         hammer2_chain_unlock(chain);
1287         chain = NULL;
1288
1289         while ((ip = pip) != NULL) {
1290                 hammer2_inode_lock_ex(ip);
1291                 parent = hammer2_chain_lookup_init(ip->chain, 0);
1292                 hammer2_inode_drop(ip);                 /* loop */
1293                 KKASSERT(parent->bref.type == HAMMER2_BREF_TYPE_INODE);
1294                 chain = hammer2_chain_lookup(&parent, lhc, lhc, 0);
1295                 hammer2_chain_lookup_done(parent);
1296                 if (chain)
1297                         break;
1298                 pip = ip->pip;          /* safe, ip held locked */
1299                 if (pip)
1300                         hammer2_inode_ref(pip);         /* loop */
1301                 hammer2_inode_unlock_ex(ip);
1302         }
1303
1304         /*
1305          * chain is locked, ip is locked.  Unlock ip, return the locked
1306          * chain.  *ipp is already set w/a ref count and not locked.
1307          *
1308          * (parent is already unlocked).
1309          */
1310         if (ip)
1311                 hammer2_inode_unlock_ex(ip);
1312         *chainp = chain;
1313         if (chain) {
1314                 KKASSERT(chain->bref.type == HAMMER2_BREF_TYPE_INODE);
1315                 /* already locked */
1316                 return (0);
1317         } else {
1318                 return (EIO);
1319         }
1320 }
1321
1322 /*
1323  * Find the directory common to both fdip and tdip, hold and return
1324  * its inode.
1325  */
1326 hammer2_inode_t *
1327 hammer2_inode_common_parent(hammer2_inode_t *fdip, hammer2_inode_t *tdip)
1328 {
1329         hammer2_inode_t *scan1;
1330         hammer2_inode_t *scan2;
1331
1332         /*
1333          * We used to have a depth field but it complicated matters too
1334          * much for directory renames.  So now its ugly.  Check for
1335          * simple cases before giving up and doing it the expensive way.
1336          *
1337          * XXX need a bottom-up topology stability lock
1338          */
1339         if (fdip == tdip || fdip == tdip->pip) {
1340                 hammer2_inode_ref(fdip);
1341                 return(fdip);
1342         }
1343         if (fdip->pip == tdip) {
1344                 hammer2_inode_ref(tdip);
1345                 return(tdip);
1346         }
1347
1348         /*
1349          * XXX not MPSAFE
1350          */
1351         for (scan1 = fdip; scan1->pmp == fdip->pmp; scan1 = scan1->pip) {
1352                 scan2 = tdip;
1353                 while (scan2->pmp == tdip->pmp) {
1354                         if (scan1 == scan2) {
1355                                 hammer2_inode_ref(scan1);
1356                                 return(scan1);
1357                         }
1358                         scan2 = scan2->pip;
1359                 }
1360         }
1361         panic("hammer2_inode_common_parent: no common parent %p %p\n",
1362               fdip, tdip);
1363         /* NOT REACHED */
1364         return(NULL);
1365 }