hammer2 - serialized flush work part 4
[dragonfly.git] / sys / vfs / hammer2 / hammer2_inode.c
1 /*
2  * Copyright (c) 2011-2012 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(hmp, 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(hmp, 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, disconnecting it from its chain.  The inode must be
283  * exclusively locked.
284  *
285  * The inode will be unlocked by this function.  Note however that any related
286  * chain returned by the hammer2_inode_lock_*() call will NOT be unlocked
287  * by this function.  The related chain is dropped to undo the ref that
288  * hammer2_inode_get() put on it.
289  *
290  * passed_chain is unlocked normally and does not have to be directly
291  * associated with (ip).  This is simply so the API works the same as
292  * the hammer2_inode_unlock_ex() API.  NULL is ok.
293  */
294 void
295 hammer2_inode_put(hammer2_inode_t *ip, hammer2_chain_t *passed_chain)
296 {
297         hammer2_mount_t *hmp = ip->hmp;
298         hammer2_inode_t *pip;
299         hammer2_chain_t *chain;
300
301         /*
302          * Disconnect chain
303          */
304         if ((chain = ip->chain) != NULL) {
305                 ip->chain = NULL;
306                 hammer2_chain_drop(hmp, chain);         /* from *_get() */
307         }
308         KKASSERT(ip->topo_cst.count == -1);     /* one excl lock allowed */
309
310         /*
311          * Disconnect pip
312          */
313         if ((pip = ip->pip) != NULL) {
314                 ip->pip = NULL;
315                 hammer2_inode_drop(pip);
316         }
317
318         /*
319          * clean up the ip, we use an inode_unlock_ex-compatible API.
320          */
321         hammer2_inode_unlock_ex(ip, passed_chain);
322 }
323
324 /*
325  * Create a new inode in the specified directory using the vattr to
326  * figure out the type of inode.
327  *
328  * If no error occurs the new inode with its chain locked is returned in
329  * *nipp, otherwise an error is returned and *nipp is set to NULL.
330  *
331  * If vap and/or cred are NULL the related fields are not set and the
332  * inode type defaults to a directory.  This is used when creating PFSs
333  * under the super-root, so the inode number is set to 1 in this case.
334  *
335  * dip is not locked on entry.
336  */
337 int
338 hammer2_inode_create(hammer2_inode_t *dip,
339                      struct vattr *vap, struct ucred *cred,
340                      const uint8_t *name, size_t name_len,
341                      hammer2_inode_t **nipp, hammer2_chain_t **nchainp)
342 {
343         hammer2_inode_data_t *nipdata;
344         hammer2_mount_t *hmp;
345         hammer2_chain_t *chain;
346         hammer2_chain_t *parent;
347         hammer2_inode_t *nip;
348         hammer2_key_t lhc;
349         int error;
350         uid_t xuid;
351         uuid_t dip_uid;
352         uuid_t dip_gid;
353         uint32_t dip_mode;
354
355         hmp = dip->hmp;
356         lhc = hammer2_dirhash(name, name_len);
357
358         /*
359          * Locate the inode or indirect block to create the new
360          * entry in.  At the same time check for key collisions
361          * and iterate until we don't get one.
362          */
363 retry:
364         parent = hammer2_inode_lock_ex(dip);
365
366         dip_uid = parent->data->ipdata.uid;
367         dip_gid = parent->data->ipdata.gid;
368         dip_mode = parent->data->ipdata.mode;
369
370         error = 0;
371         while (error == 0) {
372                 chain = hammer2_chain_lookup(hmp, &parent, lhc, lhc, 0);
373                 if (chain == NULL)
374                         break;
375                 if ((lhc & HAMMER2_DIRHASH_VISIBLE) == 0)
376                         error = ENOSPC;
377                 if ((lhc & HAMMER2_DIRHASH_LOMASK) == HAMMER2_DIRHASH_LOMASK)
378                         error = ENOSPC;
379                 hammer2_chain_unlock(hmp, chain);
380                 chain = NULL;
381                 ++lhc;
382         }
383         if (error == 0) {
384                 chain = hammer2_chain_create(hmp, parent, NULL, lhc, 0,
385                                              HAMMER2_BREF_TYPE_INODE,
386                                              HAMMER2_INODE_BYTES,
387                                              &error);
388         }
389
390         hammer2_inode_unlock_ex(dip, parent);
391
392         /*
393          * Handle the error case
394          */
395         if (error) {
396                 KKASSERT(chain == NULL);
397                 if (error == EAGAIN) {
398                         hammer2_chain_wait(hmp, parent);
399                         goto retry;
400                 }
401                 *nipp = NULL;
402                 *nchainp = NULL;
403                 return (error);
404         }
405
406         /*
407          * Set up the new inode.
408          *
409          * NOTE: *_get() integrates chain's lock into the inode lock.
410          */
411         nip = hammer2_inode_get(dip->hmp, dip->pmp, dip, chain);
412         *nipp = nip;
413         *nchainp = chain;
414         nipdata = &chain->data->ipdata;
415
416         hammer2_voldata_lock(hmp);
417         if (vap) {
418                 nipdata->type = hammer2_get_obj_type(vap->va_type);
419                 nipdata->inum = hmp->voldata.alloc_tid++;
420                 /* XXX modify/lock */
421         } else {
422                 nipdata->type = HAMMER2_OBJTYPE_DIRECTORY;
423                 nipdata->inum = 1;
424         }
425         hammer2_voldata_unlock(hmp);
426         nipdata->version = HAMMER2_INODE_VERSION_ONE;
427         hammer2_update_time(&nipdata->ctime);
428         nipdata->mtime = nipdata->ctime;
429         if (vap)
430                 nipdata->mode = vap->va_mode;
431         nipdata->nlinks = 1;
432         if (vap) {
433                 if (dip) {
434                         xuid = hammer2_to_unix_xid(&dip_uid);
435                         xuid = vop_helper_create_uid(dip->pmp->mp,
436                                                      dip_mode,
437                                                      xuid,
438                                                      cred,
439                                                      &vap->va_mode);
440                 } else {
441                         xuid = 0;
442                 }
443                 if (vap->va_vaflags & VA_UID_UUID_VALID)
444                         nipdata->uid = vap->va_uid_uuid;
445                 else if (vap->va_uid != (uid_t)VNOVAL)
446                         hammer2_guid_to_uuid(&nipdata->uid, vap->va_uid);
447                 else
448                         hammer2_guid_to_uuid(&nipdata->uid, xuid);
449
450                 if (vap->va_vaflags & VA_GID_UUID_VALID)
451                         nipdata->gid = vap->va_gid_uuid;
452                 else if (vap->va_gid != (gid_t)VNOVAL)
453                         hammer2_guid_to_uuid(&nipdata->gid, vap->va_gid);
454                 else if (dip)
455                         nipdata->gid = dip_gid;
456         }
457
458         /*
459          * Regular files and softlinks allow a small amount of data to be
460          * directly embedded in the inode.  This flag will be cleared if
461          * the size is extended past the embedded limit.
462          */
463         if (nipdata->type == HAMMER2_OBJTYPE_REGFILE ||
464             nipdata->type == HAMMER2_OBJTYPE_SOFTLINK) {
465                 nipdata->op_flags |= HAMMER2_OPFLAG_DIRECTDATA;
466         }
467
468         KKASSERT(name_len < HAMMER2_INODE_MAXNAME);
469         bcopy(name, nipdata->filename, name_len);
470         nipdata->name_key = lhc;
471         nipdata->name_len = name_len;
472
473         return (0);
474 }
475
476 /*
477  * Create a duplicate of the inode (chain) in the specified target directory
478  * (dip), return the duplicated chain in *nchainp (locked).  chain is locked
479  * on call and remains locked on return.
480  *
481  * If name is NULL the inode is duplicated as a hidden directory entry.
482  *
483  * XXX name needs to be NULL for now.
484  */
485 int
486 hammer2_inode_duplicate(hammer2_inode_t *dip,
487                         hammer2_chain_t *ochain, hammer2_chain_t **nchainp)
488 {
489         hammer2_inode_data_t *nipdata;
490         hammer2_mount_t *hmp;
491         hammer2_chain_t *parent;
492         hammer2_chain_t *chain;
493         hammer2_key_t lhc;
494         int error = 0;
495
496         hmp = dip->hmp;
497         lhc = ochain->data->ipdata.inum;
498         *nchainp = NULL;
499         KKASSERT((lhc & HAMMER2_DIRHASH_VISIBLE) == 0);
500
501         /*
502          * Locate the inode or indirect block to create the new
503          * entry in.
504          *
505          * There should be no key collisions with invisible inode keys.
506          */
507 retry:
508         parent = dip->chain;
509         hammer2_chain_lock(hmp, parent, HAMMER2_RESOLVE_ALWAYS);
510         chain = hammer2_chain_lookup(hmp, &parent, lhc, lhc, 0);
511         if (chain) {
512                 hammer2_chain_unlock(hmp, chain);
513                 chain = NULL;
514                 error = ENOSPC;
515         }
516
517         /*
518          * Create entry in common parent directory.
519          */
520         if (error == 0) {
521                 chain = hammer2_chain_create(hmp, parent, NULL, lhc, 0,
522                                              HAMMER2_BREF_TYPE_INODE, /* n/a */
523                                              HAMMER2_INODE_BYTES,     /* n/a */
524                                              &error);
525         }
526
527         /*
528          * Clean up, but we need to retain a ref on parent so we can wait
529          * on it for certain errors.
530          */
531         if (error == EAGAIN)
532                 hammer2_chain_ref(hmp, parent);
533         hammer2_chain_unlock(hmp, parent);
534
535         /*
536          * Handle the error case
537          */
538         if (error) {
539                 KKASSERT(chain == NULL);
540                 if (error == EAGAIN) {
541                         hammer2_chain_wait(hmp, parent);
542                         hammer2_chain_drop(hmp, parent);
543                         goto retry;
544                 }
545                 return (error);
546         }
547
548         /*
549          * XXX This is currently a horrible hack.  Well, if we wanted to
550          *     duplicate a file, i.e. as in a snapshot, we definitely
551          *     would have to flush it first.
552          *
553          *     For hardlink target generation we can theoretically move any
554          *     active chain structures without flushing, but that gets really
555          *     iffy for code which follows chain->parent and ip->pip links.
556          *
557          * XXX only works with files.  Duplicating a directory hierarchy
558          *     requires a flush but doesn't deal with races post-flush.
559          *     Well, it would work I guess, but you might catch some files
560          *     mid-operation.
561          *
562          * We cannot leave ochain with any in-memory chains because (for a
563          * hardlink), ochain will become a OBJTYPE_HARDLINK which is just a
564          * pointer to the real hardlink's inum and can't have any sub-chains.
565          * XXX might be 0-ref chains left.
566          */
567         hammer2_chain_flush(hmp, ochain, 0);
568         /*KKASSERT(RB_EMPTY(&ochain.rbhead));*/
569
570         hammer2_chain_modify(hmp, chain, 0);
571         nipdata = &chain->data->ipdata;
572         *nipdata = ochain->data->ipdata;
573
574         /*
575          * Directory entries are inodes but this is a hidden hardlink
576          * target.  The name isn't used but to ease debugging give it
577          * a name after its inode number.
578          */
579         ksnprintf(nipdata->filename, sizeof(nipdata->filename),
580                   "0x%016jx", (intmax_t)nipdata->inum);
581         nipdata->name_len = strlen(nipdata->filename);
582         nipdata->name_key = lhc;
583
584         *nchainp = chain;
585
586         return (0);
587 }
588
589 /*
590  * Connect *chainp to the media topology represented by (dip, name, len).
591  * A directory entry is created which points to *chainp.  *chainp is then
592  * unlocked and set to NULL.
593  *
594  * If *chainp is not currently connected we simply connect it up.
595  *
596  * If *chainp is already connected we create a OBJTYPE_HARDLINK entry which
597  * points to chain's inode number.  *chainp is expected to be the terminus of
598  * the hardlink sitting as a hidden file in a common parent directory
599  * in this situation.
600  *
601  * The caller always wants to reference the hardlink terminus, not the
602  * hardlink pointer that we might be creating, so we do NOT replace
603  * *chainp here, we simply unlock and NULL it out.
604  */
605 int
606 hammer2_inode_connect(hammer2_inode_t *dip, hammer2_chain_t **chainp,
607                       const uint8_t *name, size_t name_len)
608 {
609         hammer2_inode_data_t *ipdata;
610         hammer2_mount_t *hmp;
611         hammer2_chain_t *nchain;
612         hammer2_chain_t *parent;
613         hammer2_chain_t *ochain;
614         hammer2_key_t lhc;
615         int error;
616         int hlink;
617
618         hmp = dip->hmp;
619
620         ochain = *chainp;
621         *chainp = NULL;
622
623         /*
624          * Since ochain is either disconnected from the topology or represents
625          * a hardlink terminus which is always a parent of or equal to dip,
626          * we should be able to safely lock dip->chain for our setup.
627          */
628 retry:
629         parent = dip->chain;
630         hammer2_chain_lock(hmp, parent, HAMMER2_RESOLVE_ALWAYS);
631
632         lhc = hammer2_dirhash(name, name_len);
633         hlink = (ochain->parent != NULL);
634
635         /*
636          * In fake mode flush oip so we can just snapshot it downbelow.
637          */
638         if (hlink && hammer2_hardlink_enable < 0)
639                 hammer2_chain_flush(hmp, ochain, 0);
640
641         /*
642          * Locate the inode or indirect block to create the new
643          * entry in.  At the same time check for key collisions
644          * and iterate until we don't get one.
645          */
646         error = 0;
647         while (error == 0) {
648                 nchain = hammer2_chain_lookup(hmp, &parent, lhc, lhc, 0);
649                 if (nchain == NULL)
650                         break;
651                 if ((lhc & HAMMER2_DIRHASH_LOMASK) == HAMMER2_DIRHASH_LOMASK)
652                         error = ENOSPC;
653                 hammer2_chain_unlock(hmp, nchain);
654                 nchain = NULL;
655                 ++lhc;
656         }
657
658         /*
659          * Passing a non-NULL chain to hammer2_chain_create() reconnects the
660          * existing chain instead of creating a new one.  The chain's bref
661          * will be properly updated.
662          */
663         if (error == 0) {
664                 if (hlink) {
665                         nchain = hammer2_chain_create(hmp, parent,
666                                                      NULL, lhc, 0,
667                                                      HAMMER2_BREF_TYPE_INODE,
668                                                      HAMMER2_INODE_BYTES,
669                                                      &error);
670                 } else {
671                         /*
672                          * NOTE: reconnects oip->chain to the media
673                          *       topology and returns its argument
674                          *       (oip->chain).
675                          *
676                          * No additional locks or refs are obtained on
677                          * the returned chain so don't double-unlock!
678                          */
679                         nchain = hammer2_chain_create(hmp, parent,
680                                                      ochain, lhc, 0,
681                                                      HAMMER2_BREF_TYPE_INODE,
682                                                      HAMMER2_INODE_BYTES,
683                                                      &error);
684                 }
685         }
686
687         /*
688          * Unlock stuff.  This is a bit messy, if we have an EAGAIN error
689          * we need to wait for operations on parent to finish.
690          */
691         if (error == EAGAIN)
692                 hammer2_chain_ref(hmp, parent);
693         hammer2_chain_unlock(hmp, parent);
694
695         /*
696          * ochain still active.
697          *
698          * Handle the error case
699          */
700         if (error) {
701                 KKASSERT(nchain == NULL);
702                 if (error == EAGAIN) {
703                         hammer2_chain_wait(hmp, parent);
704                         hammer2_chain_drop(hmp, parent);
705                         goto retry;
706                 }
707                 hammer2_chain_unlock(hmp, ochain);
708                 return (error);
709         }
710
711         /*
712          * Directory entries are inodes so if the name has changed we have
713          * to update the inode.
714          *
715          * When creating an OBJTYPE_HARDLINK entry remember to unlock the
716          * chain, the caller will access the hardlink via the actual hardlink
717          * target file and not the hardlink pointer entry.
718          */
719         if (hlink && hammer2_hardlink_enable >= 0) {
720                 /*
721                  * Create the HARDLINK pointer.  oip represents the hardlink
722                  * target in this situation.
723                  *
724                  * NOTE: *_get() integrates chain's lock into the inode lock.
725                  */
726                 hammer2_chain_modify(hmp, nchain, 0);
727                 KKASSERT(name_len < HAMMER2_INODE_MAXNAME);
728                 ipdata = &nchain->data->ipdata;
729                 bcopy(name, ipdata->filename, name_len);
730                 ipdata->name_key = lhc;
731                 ipdata->name_len = name_len;
732                 ipdata->target_type = ochain->data->ipdata.type;
733                 ipdata->type = HAMMER2_OBJTYPE_HARDLINK;
734                 ipdata->inum = ochain->data->ipdata.inum;
735                 ipdata->nlinks = 1;
736                 kprintf("created hardlink %*.*s\n",
737                         (int)name_len, (int)name_len, name);
738                 hammer2_chain_unlock(hmp, nchain);
739         } else if (hlink && hammer2_hardlink_enable < 0) {
740                 /*
741                  * Create a snapshot (hardlink fake mode for debugging).
742                  *
743                  * NOTE: *_get() integrates nchain's lock into the inode lock.
744                  */
745                 hammer2_chain_modify(hmp, nchain, 0);
746                 KKASSERT(name_len < HAMMER2_INODE_MAXNAME);
747                 ipdata = &nchain->data->ipdata;
748                 *ipdata = ochain->data->ipdata;
749                 bcopy(name, ipdata->filename, name_len);
750                 ipdata->name_key = lhc;
751                 ipdata->name_len = name_len;
752                 kprintf("created fake hardlink %*.*s\n",
753                         (int)name_len, (int)name_len, name);
754                 hammer2_chain_unlock(hmp, nchain);
755         } else {
756                 /*
757                  * Normally disconnected inode (e.g. during a rename) that
758                  * was reconnected.  We must fixup the name stored in
759                  * oip.
760                  *
761                  * We are using oip as chain, already locked by caller,
762                  * do not unlock it.
763                  */
764                 hammer2_chain_modify(hmp, ochain, 0);
765                 ipdata = &ochain->data->ipdata;
766
767                 if (ipdata->name_len != name_len ||
768                     bcmp(ipdata->filename, name, name_len) != 0) {
769                         KKASSERT(name_len < HAMMER2_INODE_MAXNAME);
770                         bcopy(name, ipdata->filename, name_len);
771                         ipdata->name_key = lhc;
772                         ipdata->name_len = name_len;
773                 }
774                 ipdata->nlinks = 1;
775         }
776         hammer2_chain_unlock(hmp, ochain);
777         return (0);
778 }
779
780 /*
781  * Unlink the file from the specified directory inode.  The directory inode
782  * does not need to be locked.  The caller should pass a non-NULL (ip)
783  * representing the object being removed only if the related vnode is
784  * potentially inactive (not referenced in the caller's active path),
785  * so we can vref/vrele it to trigger the VOP_INACTIVE path and properly
786  * recycle it.
787  *
788  * isdir determines whether a directory/non-directory check should be made.
789  * No check is made if isdir is set to -1.
790  *
791  * If retain_chain is non-NULL this function can fail with an EAGAIN if it
792  * catches the object in the middle of a flush.
793  */
794 int
795 hammer2_unlink_file(hammer2_inode_t *dip,
796                     const uint8_t *name, size_t name_len,
797                     int isdir, hammer2_chain_t *retain_chain)
798 {
799         hammer2_inode_data_t *ipdata;
800         hammer2_mount_t *hmp;
801         hammer2_chain_t *parent;
802         hammer2_chain_t *ochain;
803         hammer2_chain_t *chain;
804         hammer2_chain_t *dparent;
805         hammer2_chain_t *dchain;
806         hammer2_key_t lhc;
807         int error;
808         int parent_ref;
809         uint8_t type;
810
811         parent_ref = 0;
812         error = 0;
813         ochain = NULL;
814         hmp = dip->hmp;
815         lhc = hammer2_dirhash(name, name_len);
816
817         /*
818          * Search for the filename in the directory
819          */
820         parent = hammer2_inode_lock_ex(dip);
821         chain = hammer2_chain_lookup(hmp, &parent,
822                                      lhc, lhc + HAMMER2_DIRHASH_LOMASK,
823                                      0);
824         while (chain) {
825                 if (chain->bref.type == HAMMER2_BREF_TYPE_INODE &&
826                     name_len == chain->data->ipdata.name_len &&
827                     bcmp(name, chain->data->ipdata.filename, name_len) == 0) {
828                         break;
829                 }
830                 chain = hammer2_chain_next(hmp, &parent, chain,
831                                            lhc, lhc + HAMMER2_DIRHASH_LOMASK,
832                                            0);
833         }
834         hammer2_inode_unlock_ex(dip, NULL);     /* retain parent */
835
836         /*
837          * Not found or wrong type (isdir < 0 disables the type check).
838          * If a hardlink pointer, type checks use the hardlink target.
839          */
840         if (chain == NULL) {
841                 error = ENOENT;
842                 goto done;
843         }
844         if ((type = chain->data->ipdata.type) == HAMMER2_OBJTYPE_HARDLINK)
845                 type = chain->data->ipdata.target_type;
846
847         if (type == HAMMER2_OBJTYPE_DIRECTORY && isdir == 0) {
848                 error = ENOTDIR;
849                 goto done;
850         }
851         if (type != HAMMER2_OBJTYPE_DIRECTORY && isdir == 1) {
852                 error = EISDIR;
853                 goto done;
854         }
855
856         /*
857          * Hardlink must be resolved.  We can't hold parent locked while we
858          * do this or we could deadlock.
859          *
860          * On success chain will be adjusted to point at the hardlink target
861          * and ochain will point to the hardlink pointer in the original
862          * directory.  Otherwise chain remains pointing to the original.
863          */
864         if (chain->data->ipdata.type == HAMMER2_OBJTYPE_HARDLINK) {
865                 KKASSERT(parent_ref == 0);
866                 hammer2_chain_unlock(hmp, parent);
867                 parent = NULL;
868                 error = hammer2_hardlink_find(dip, &chain, &ochain);
869         }
870
871         /*
872          * If this is a directory the directory must be empty.  However, if
873          * isdir < 0 we are doing a rename and the directory does not have
874          * to be empty.
875          *
876          * NOTE: We check the full key range here which covers both visible
877          *       and invisible entries.  Theoretically there should be no
878          *       invisible (hardlink target) entries if there are no visible
879          *       entries.
880          */
881         if (type == HAMMER2_OBJTYPE_DIRECTORY && isdir >= 0) {
882                 dparent = chain;
883                 hammer2_chain_lock(hmp, dparent, HAMMER2_RESOLVE_ALWAYS);
884                 dchain = hammer2_chain_lookup(hmp, &dparent,
885                                               0, (hammer2_key_t)-1,
886                                               HAMMER2_LOOKUP_NODATA);
887                 if (dchain) {
888                         hammer2_chain_unlock(hmp, dchain);
889                         hammer2_chain_unlock(hmp, dparent);
890                         error = ENOTEMPTY;
891                         goto done;
892                 }
893                 hammer2_chain_unlock(hmp, dparent);
894                 dparent = NULL;
895                 /* dchain NULL */
896         }
897
898         /*
899          * Ok, we can now unlink the chain.  We always decrement nlinks even
900          * if the entry can be deleted in case someone has the file open and
901          * does an fstat().
902          *
903          * The chain itself will no longer be in the on-media topology but
904          * can still be flushed to the media (e.g. if an open descriptor
905          * remains).  When the last vnode/ip ref goes away the chain will
906          * be marked unmodified, avoiding any further (now unnecesary) I/O.
907          *
908          * A non-NULL ochain indicates a hardlink.
909          */
910         if (ochain) {
911                 /*
912                  * Delete the original hardlink pointer.
913                  *
914                  * NOTE: parent from above is NULL when ochain != NULL
915                  *       so we can reuse it.
916                  */
917                 hammer2_chain_lock(hmp, ochain, HAMMER2_RESOLVE_ALWAYS);
918                 parent_ref = 1;
919                 for (;;) {
920                         parent = ochain->parent;
921                         hammer2_chain_ref(hmp, parent);
922                         hammer2_chain_unlock(hmp, ochain);
923                         hammer2_chain_lock(hmp, parent, HAMMER2_RESOLVE_ALWAYS);
924                         hammer2_chain_lock(hmp, ochain, HAMMER2_RESOLVE_ALWAYS);
925                         if (ochain->parent == parent)
926                                 break;
927                         hammer2_chain_unlock(hmp, parent);
928                         hammer2_chain_drop(hmp, parent);
929                 }
930
931                 if (ochain == retain_chain && ochain->flushing) {
932                         hammer2_chain_unlock(hmp, ochain);
933                         error = EAGAIN;
934                         goto done;
935                 }
936                 hammer2_chain_delete(hmp, parent, ochain,
937                                      (ochain == retain_chain));
938                 hammer2_chain_unlock(hmp, ochain);
939                 hammer2_chain_unlock(hmp, parent);
940                 hammer2_chain_drop(hmp, parent);
941                 parent = NULL;
942
943                 /*
944                  * Then decrement nlinks on hardlink target, deleting
945                  * the target when nlinks drops to 0.
946                  */
947                 if (chain->data->ipdata.nlinks == 1) {
948                         dparent = chain->parent;
949                         hammer2_chain_ref(hmp, chain);
950                         hammer2_chain_unlock(hmp, chain);
951                         hammer2_chain_lock(hmp, dparent,
952                                            HAMMER2_RESOLVE_ALWAYS);
953                         hammer2_chain_lock(hmp, chain,
954                                            HAMMER2_RESOLVE_ALWAYS);
955                         hammer2_chain_drop(hmp, chain);
956                         hammer2_chain_modify(hmp, chain, 0);
957                         --chain->data->ipdata.nlinks;
958                         hammer2_chain_delete(hmp, dparent, chain, 0);
959                         hammer2_chain_unlock(hmp, dparent);
960                 } else {
961                         hammer2_chain_modify(hmp, chain, 0);
962                         --chain->data->ipdata.nlinks;
963                 }
964         } else {
965                 /*
966                  * Otherwise this was not a hardlink and we can just
967                  * remove the entry and decrement nlinks.
968                  *
969                  * NOTE: *_get() integrates chain's lock into the inode lock.
970                  */
971                 ipdata = &chain->data->ipdata;
972                 if (chain == retain_chain && chain->flushing) {
973                         error = EAGAIN;
974                         goto done;
975                 }
976                 hammer2_chain_modify(hmp, chain, 0);
977                 --ipdata->nlinks;
978                 hammer2_chain_delete(hmp, parent, chain,
979                                      (retain_chain == chain));
980         }
981
982         error = 0;
983 done:
984         if (chain)
985                 hammer2_chain_unlock(hmp, chain);
986         if (parent) {
987                 hammer2_chain_unlock(hmp, parent);
988                 if (parent_ref)
989                         hammer2_chain_drop(hmp, parent);
990         }
991         if (ochain)
992                 hammer2_chain_drop(hmp, ochain);
993
994         return error;
995 }
996
997 /*
998  * Calculate the allocation size for the file fragment straddling EOF
999  */
1000 int
1001 hammer2_inode_calc_alloc(hammer2_key_t filesize)
1002 {
1003         int frag = (int)filesize & HAMMER2_PBUFMASK;
1004         int radix;
1005
1006         if (frag == 0)
1007                 return(0);
1008         for (radix = HAMMER2_MINALLOCRADIX; frag > (1 << radix); ++radix)
1009                 ;
1010         return (radix);
1011 }
1012
1013 /*
1014  * Given an unlocked ip consolidate for hardlink creation, adding (nlinks)
1015  * to the file's link count and potentially relocating the file to a
1016  * directory common to ip->pip and tdip.
1017  *
1018  * If the file has to be relocated ip->chain will also be adjusted.
1019  */
1020 int
1021 hammer2_hardlink_consolidate(hammer2_inode_t *ip, hammer2_chain_t **chainp,
1022                              hammer2_inode_t *tdip, int nlinks)
1023 {
1024         hammer2_inode_data_t *ipdata;
1025         hammer2_mount_t *hmp;
1026         hammer2_inode_t *fdip;
1027         hammer2_inode_t *cdip;
1028         hammer2_chain_t *chain;
1029         hammer2_chain_t *nchain;
1030         hammer2_chain_t *parent;
1031         int error;
1032
1033         hmp = tdip->hmp;
1034         *chainp = NULL;
1035         chain = hammer2_inode_lock_ex(ip);
1036
1037         if (nlinks == 0 &&                      /* no hardlink needed */
1038             (chain->data->ipdata.name_key & HAMMER2_DIRHASH_VISIBLE)) {
1039                 hammer2_inode_unlock_ex(ip, NULL);
1040                 *chainp = chain;
1041                 return (0);
1042         }
1043         if (hammer2_hardlink_enable < 0) {      /* fake hardlinks */
1044                 hammer2_inode_unlock_ex(ip, NULL);
1045                 *chainp = chain;
1046                 return (0);
1047         }
1048         if (hammer2_hardlink_enable == 0) {     /* disallow hardlinks */
1049                 hammer2_inode_unlock_ex(ip, chain);
1050                 return (ENOTSUP);
1051         }
1052
1053         /*
1054          * cdip will be returned with a ref, but not locked.
1055          */
1056         fdip = ip->pip;
1057         cdip = hammer2_inode_common_parent(hmp, fdip, tdip);
1058
1059         /*
1060          * If no change in the hardlink's target directory is required and
1061          * this is already a hardlink target, all we need to do is adjust
1062          * the link count.
1063          */
1064         if (cdip == fdip &&
1065             (chain->data->ipdata.name_key & HAMMER2_DIRHASH_VISIBLE) == 0) {
1066                 if (nlinks) {
1067                         hammer2_chain_modify(hmp, chain, 0);
1068                         chain->data->ipdata.nlinks += nlinks;
1069                 }
1070                 *chainp = chain;
1071                 error = 0;
1072                 goto done;
1073         }
1074
1075         /*
1076          * We either have to move an existing hardlink target or we have
1077          * to create a fresh hardlink target.
1078          *
1079          * Hardlink targets are hidden inodes in a parent directory common
1080          * to all directory entries referencing the hardlink.
1081          */
1082         error = hammer2_inode_duplicate(cdip, chain, &nchain);
1083         if (error == 0) {
1084                 /*
1085                  * Bump nlinks on duplicated hidden inode.
1086                  */
1087                 hammer2_chain_modify(hmp, nchain, 0);
1088                 nchain->data->ipdata.nlinks += nlinks;
1089
1090                 /*
1091                  * If the old chain is not a hardlink target then replace
1092                  * it with a OBJTYPE_HARDLINK pointer.
1093                  *
1094                  * If the old chain IS a hardlink target then delete it.
1095                  */
1096                 if (chain->data->ipdata.name_key & HAMMER2_DIRHASH_VISIBLE) {
1097                         hammer2_chain_modify(hmp, chain, 0);
1098                         ipdata = &chain->data->ipdata;
1099                         ipdata->target_type = ipdata->type;
1100                         ipdata->type = HAMMER2_OBJTYPE_HARDLINK;
1101                         ipdata->uflags = 0;
1102                         ipdata->rmajor = 0;
1103                         ipdata->rminor = 0;
1104                         ipdata->ctime = 0;
1105                         ipdata->mtime = 0;
1106                         ipdata->atime = 0;
1107                         ipdata->btime = 0;
1108                         bzero(&ipdata->uid, sizeof(ipdata->uid));
1109                         bzero(&ipdata->gid, sizeof(ipdata->gid));
1110                         ipdata->op_flags = HAMMER2_OPFLAG_DIRECTDATA;
1111                         ipdata->cap_flags = 0;
1112                         ipdata->mode = 0;
1113                         ipdata->size = 0;
1114                         ipdata->nlinks = 1;
1115                         ipdata->iparent = 0;    /* XXX */
1116                         ipdata->pfs_type = 0;
1117                         ipdata->pfs_inum = 0;
1118                         bzero(&ipdata->pfs_clid, sizeof(ipdata->pfs_clid));
1119                         bzero(&ipdata->pfs_fsid, sizeof(ipdata->pfs_fsid));
1120                         ipdata->data_quota = 0;
1121                         ipdata->data_count = 0;
1122                         ipdata->inode_quota = 0;
1123                         ipdata->inode_count = 0;
1124                         ipdata->attr_tid = 0;
1125                         ipdata->dirent_tid = 0;
1126                         bzero(&ipdata->u, sizeof(ipdata->u));
1127                         /* XXX transaction ids */
1128                 } else {
1129                         kprintf("DELETE INVISIBLE\n");
1130                         for (;;) {
1131                                 parent = chain->parent;
1132                                 hammer2_chain_ref(hmp, parent);
1133                                 hammer2_chain_ref(hmp, chain);
1134                                 hammer2_chain_unlock(hmp, chain);
1135                                 hammer2_chain_lock(hmp, parent,
1136                                                    HAMMER2_RESOLVE_ALWAYS);
1137                                 hammer2_chain_lock(hmp, chain,
1138                                                    HAMMER2_RESOLVE_ALWAYS);
1139                                 hammer2_chain_drop(hmp, chain);
1140                                 if (chain->parent == parent)
1141                                         break;
1142                                 hammer2_chain_unlock(hmp, parent);
1143                                 hammer2_chain_drop(hmp, parent);
1144                         }
1145                         hammer2_chain_delete(hmp, parent, chain, 0);
1146                         hammer2_chain_unlock(hmp, parent);
1147                         hammer2_chain_drop(hmp, parent);
1148                 }
1149
1150                 /*
1151                  * Replace ip->chain with nchain (ip is still locked).
1152                  */
1153                 hammer2_chain_ref(hmp, nchain);                 /* ip->chain */
1154                 if (ip->chain)
1155                         hammer2_chain_drop(hmp, ip->chain);     /* ip->chain */
1156                 ip->chain = nchain;
1157
1158                 hammer2_chain_unlock(hmp, chain);
1159                 *chainp = nchain;
1160         } else {
1161                 hammer2_chain_unlock(hmp, chain);
1162         }
1163
1164         /*
1165          * Cleanup, chain/nchain already dealt with.
1166          */
1167 done:
1168         hammer2_inode_unlock_ex(ip, NULL);
1169         hammer2_inode_drop(cdip);
1170
1171         return (error);
1172 }
1173
1174 /*
1175  * If (*ochainp) is non-NULL it points to the forward OBJTYPE_HARDLINK
1176  * inode while (*chainp) points to the resolved (hidden hardlink
1177  * target) inode.  In this situation when nlinks is 1 we wish to
1178  * deconsolidate the hardlink, moving it back to the directory that now
1179  * represents the only remaining link.
1180  */
1181 int
1182 hammer2_hardlink_deconsolidate(hammer2_inode_t *dip,
1183                                hammer2_chain_t **chainp,
1184                                hammer2_chain_t **ochainp)
1185 {
1186         if (*ochainp == NULL)
1187                 return (0);
1188         /* XXX */
1189         return (0);
1190 }
1191
1192 /*
1193  * The caller presents a locked *chainp pointing to a HAMMER2_BREF_TYPE_INODE
1194  * with an obj_type of HAMMER2_OBJTYPE_HARDLINK.  This routine will gobble
1195  * the *chainp and return a new locked *chainp representing the file target
1196  * (the original *chainp will be unlocked).
1197  *
1198  * When a match is found the chain representing the original HARDLINK
1199  * will be returned in *ochainp with a ref, but not locked.
1200  *
1201  * When no match is found *chainp is set to NULL and EIO is returned.
1202  * (*ochainp) will still be set to the original chain with a ref but not
1203  * locked.
1204  */
1205 int
1206 hammer2_hardlink_find(hammer2_inode_t *dip, hammer2_chain_t **chainp,
1207                       hammer2_chain_t **ochainp)
1208 {
1209         hammer2_mount_t *hmp = dip->hmp;
1210         hammer2_chain_t *chain = *chainp;
1211         hammer2_chain_t *parent;
1212         hammer2_inode_t *ip;
1213         hammer2_inode_t *pip;
1214         hammer2_key_t lhc;
1215
1216         pip = dip;
1217         hammer2_inode_ref(pip);         /* for loop */
1218         hammer2_chain_ref(hmp, chain);  /* for (*ochainp) */
1219
1220         *ochainp = chain;
1221
1222         /*
1223          * Locate the hardlink.  pip is referenced and not locked,
1224          * ipp.
1225          *
1226          * chain is reused.
1227          */
1228         lhc = chain->data->ipdata.inum;
1229         hammer2_chain_unlock(hmp, chain);
1230         chain = NULL;
1231
1232         while ((ip = pip) != NULL) {
1233                 parent = hammer2_inode_lock_ex(ip);
1234                 hammer2_inode_drop(ip);                 /* loop */
1235                 KKASSERT(parent->bref.type == HAMMER2_BREF_TYPE_INODE);
1236                 chain = hammer2_chain_lookup(hmp, &parent, lhc, lhc, 0);
1237                 hammer2_chain_unlock(hmp, parent);
1238                 if (chain)
1239                         break;
1240                 pip = ip->pip;          /* safe, ip held locked */
1241                 if (pip)
1242                         hammer2_inode_ref(pip);         /* loop */
1243                 hammer2_inode_unlock_ex(ip, NULL);
1244         }
1245
1246         /*
1247          * chain is locked, ip is locked.  Unlock ip, return the locked
1248          * chain.  *ipp is already set w/a ref count and not locked.
1249          *
1250          * (parent is already unlocked).
1251          */
1252         hammer2_inode_unlock_ex(ip, NULL);
1253         *chainp = chain;
1254         if (chain) {
1255                 KKASSERT(chain->bref.type == HAMMER2_BREF_TYPE_INODE);
1256                 /* already locked */
1257                 return (0);
1258         } else {
1259                 return (EIO);
1260         }
1261 }
1262
1263 /*
1264  * Find the directory common to both fdip and tdip, hold and return
1265  * its inode.
1266  */
1267 hammer2_inode_t *
1268 hammer2_inode_common_parent(hammer2_mount_t *hmp,
1269                             hammer2_inode_t *fdip, hammer2_inode_t *tdip)
1270 {
1271         hammer2_inode_t *scan1;
1272         hammer2_inode_t *scan2;
1273
1274         /*
1275          * We used to have a depth field but it complicated matters too
1276          * much for directory renames.  So now its ugly.  Check for
1277          * simple cases before giving up and doing it the expensive way.
1278          *
1279          * XXX need a bottom-up topology stability lock
1280          */
1281         if (fdip == tdip || fdip == tdip->pip) {
1282                 hammer2_inode_ref(fdip);
1283                 return(fdip);
1284         }
1285         if (fdip->pip == tdip) {
1286                 hammer2_inode_ref(tdip);
1287                 return(tdip);
1288         }
1289
1290         /*
1291          * XXX not MPSAFE
1292          */
1293         for (scan1 = fdip; scan1->pmp == fdip->pmp; scan1 = scan1->pip) {
1294                 scan2 = tdip;
1295                 while (scan2->pmp == tdip->pmp) {
1296                         if (scan1 == scan2) {
1297                                 hammer2_inode_ref(scan1);
1298                                 return(scan1);
1299                         }
1300                         scan2 = scan2->pip;
1301                 }
1302         }
1303         panic("hammer2_inode_common_parent: no common parent %p %p\n",
1304               fdip, tdip);
1305         /* NOT REACHED */
1306         return(NULL);
1307 }