xref: /freebsd/sys/fs/unionfs/union_vnops.c (revision 6b3455a7665208c366849f0b2b3bc916fb97516e)
1 /*
2  * Copyright (c) 1992, 1993, 1994, 1995 Jan-Simon Pendry.
3  * Copyright (c) 1992, 1993, 1994, 1995
4  *	The Regents of the University of California.  All rights reserved.
5  *
6  * This code is derived from software contributed to Berkeley by
7  * Jan-Simon Pendry.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
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 the
16  *    documentation and/or other materials provided with the distribution.
17  * 4. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  *
33  *	@(#)union_vnops.c	8.32 (Berkeley) 6/23/95
34  * $FreeBSD$
35  */
36 
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/fcntl.h>
40 #include <sys/stat.h>
41 #include <sys/kernel.h>
42 #include <sys/vnode.h>
43 #include <sys/mount.h>
44 #include <sys/namei.h>
45 #include <sys/malloc.h>
46 #include <sys/bio.h>
47 #include <sys/buf.h>
48 #include <sys/lock.h>
49 #include <sys/sysctl.h>
50 #include <sys/unistd.h>
51 #include <sys/acl.h>
52 #include <sys/event.h>
53 #include <sys/extattr.h>
54 #include <sys/mac.h>
55 #include <fs/unionfs/union.h>
56 
57 #include <vm/vm.h>
58 #include <vm/vnode_pager.h>
59 
60 #include <vm/vm_page.h>
61 #include <vm/vm_object.h>
62 
63 int uniondebug = 0;
64 
65 #if UDEBUG_ENABLED
66 SYSCTL_INT(_vfs, OID_AUTO, uniondebug, CTLFLAG_RW, &uniondebug, 0, "");
67 #else
68 SYSCTL_INT(_vfs, OID_AUTO, uniondebug, CTLFLAG_RD, &uniondebug, 0, "");
69 #endif
70 
71 static int	union_access(struct vop_access_args *ap);
72 static int	union_aclcheck(struct vop_aclcheck_args *ap);
73 static int	union_advlock(struct vop_advlock_args *ap);
74 static int	union_close(struct vop_close_args *ap);
75 static int	union_closeextattr(struct vop_closeextattr_args *ap);
76 static int	union_create(struct vop_create_args *ap);
77 static int	union_createvobject(struct vop_createvobject_args *ap);
78 static int	union_deleteextattr(struct vop_deleteextattr_args *ap);
79 static int	union_destroyvobject(struct vop_destroyvobject_args *ap);
80 static int	union_fsync(struct vop_fsync_args *ap);
81 static int	union_getacl(struct vop_getacl_args *ap);
82 static int	union_getattr(struct vop_getattr_args *ap);
83 static int	union_getextattr(struct vop_getextattr_args *ap);
84 static int	union_getvobject(struct vop_getvobject_args *ap);
85 static int	union_inactive(struct vop_inactive_args *ap);
86 static int	union_ioctl(struct vop_ioctl_args *ap);
87 static int	union_lease(struct vop_lease_args *ap);
88 static int	union_link(struct vop_link_args *ap);
89 static int	union_listextattr(struct vop_listextattr_args *ap);
90 static int	union_lookup(struct vop_lookup_args *ap);
91 static int	union_lookup1(struct vnode *udvp, struct vnode **dvp,
92 				   struct vnode **vpp,
93 				   struct componentname *cnp);
94 static int	union_mkdir(struct vop_mkdir_args *ap);
95 static int	union_mknod(struct vop_mknod_args *ap);
96 static int	union_open(struct vop_open_args *ap);
97 static int	union_openextattr(struct vop_openextattr_args *ap);
98 static int	union_pathconf(struct vop_pathconf_args *ap);
99 static int	union_print(struct vop_print_args *ap);
100 static int	union_read(struct vop_read_args *ap);
101 static int	union_readdir(struct vop_readdir_args *ap);
102 static int	union_readlink(struct vop_readlink_args *ap);
103 static int	union_getwritemount(struct vop_getwritemount_args *ap);
104 static int	union_reclaim(struct vop_reclaim_args *ap);
105 static int	union_remove(struct vop_remove_args *ap);
106 static int	union_rename(struct vop_rename_args *ap);
107 static int	union_revoke(struct vop_revoke_args *ap);
108 static int	union_rmdir(struct vop_rmdir_args *ap);
109 static int	union_poll(struct vop_poll_args *ap);
110 static int	union_setacl(struct vop_setacl_args *ap);
111 static int	union_setattr(struct vop_setattr_args *ap);
112 static int	union_setlabel(struct vop_setlabel_args *ap);
113 static int	union_setextattr(struct vop_setextattr_args *ap);
114 static int	union_strategy(struct vop_strategy_args *ap);
115 static int	union_symlink(struct vop_symlink_args *ap);
116 static int	union_whiteout(struct vop_whiteout_args *ap);
117 static int	union_write(struct vop_read_args *ap);
118 
119 static __inline
120 struct vnode *
121 union_lock_upper(struct union_node *un, struct thread *td)
122 {
123 	struct vnode *uppervp;
124 
125 	if ((uppervp = un->un_uppervp) != NULL) {
126 		VREF(uppervp);
127 		vn_lock(uppervp, LK_EXCLUSIVE | LK_CANRECURSE | LK_RETRY, td);
128 	}
129 	KASSERT((uppervp == NULL || vrefcnt(uppervp) > 0), ("uppervp usecount is 0"));
130 	return(uppervp);
131 }
132 
133 static __inline
134 void
135 union_unlock_upper(struct vnode *uppervp, struct thread *td)
136 {
137 	vput(uppervp);
138 }
139 
140 static __inline
141 struct vnode *
142 union_lock_other(struct union_node *un, struct thread *td)
143 {
144 	struct vnode *vp;
145 
146 	if (un->un_uppervp != NULL) {
147 		vp = union_lock_upper(un, td);
148 	} else if ((vp = un->un_lowervp) != NULL) {
149 		VREF(vp);
150 		vn_lock(vp, LK_EXCLUSIVE | LK_CANRECURSE | LK_RETRY, td);
151 	}
152 	return(vp);
153 }
154 
155 static __inline
156 void
157 union_unlock_other(struct vnode *vp, struct thread *td)
158 {
159 	vput(vp);
160 }
161 
162 /*
163  *	union_lookup:
164  *
165  *	udvp	must be exclusively locked on call and will remain
166  *		exclusively locked on return.  This is the mount point
167  *		for our filesystem.
168  *
169  *	dvp	Our base directory, locked and referenced.
170  *		The passed dvp will be dereferenced and unlocked on return
171  *		and a new dvp will be returned which is locked and
172  *		referenced in the same variable.
173  *
174  *	vpp	is filled in with the result if no error occured,
175  *		locked and ref'd.
176  *
177  *		If an error is returned, *vpp is set to NULLVP.  If no
178  *		error occurs, *vpp is returned with a reference and an
179  *		exclusive lock.
180  */
181 
182 static int
183 union_lookup1(udvp, pdvp, vpp, cnp)
184 	struct vnode *udvp;
185 	struct vnode **pdvp;
186 	struct vnode **vpp;
187 	struct componentname *cnp;
188 {
189 	int error;
190 	struct thread *td = cnp->cn_thread;
191 	struct vnode *dvp = *pdvp;
192 	struct vnode *tdvp;
193 	struct mount *mp;
194 
195 	/*
196 	 * If stepping up the directory tree, check for going
197 	 * back across the mount point, in which case do what
198 	 * lookup would do by stepping back down the mount
199 	 * hierarchy.
200 	 */
201 	if (cnp->cn_flags & ISDOTDOT) {
202 		while ((dvp != udvp) && (dvp->v_vflag & VV_ROOT)) {
203 			/*
204 			 * Don't do the NOCROSSMOUNT check
205 			 * at this level.  By definition,
206 			 * union fs deals with namespaces, not
207 			 * filesystems.
208 			 */
209 			tdvp = dvp;
210 			dvp = dvp->v_mount->mnt_vnodecovered;
211 			VREF(dvp);
212 			vput(tdvp);
213 			vn_lock(dvp, LK_EXCLUSIVE | LK_RETRY, td);
214 		}
215 	}
216 
217 	/*
218 	 * Set return dvp to be the upperdvp 'parent directory.
219 	 */
220 	*pdvp = dvp;
221 
222 	/*
223 	 * If the VOP_LOOKUP() call generates an error, tdvp is invalid and
224 	 * no changes will have been made to dvp, so we are set to return.
225 	 */
226 
227         error = VOP_LOOKUP(dvp, &tdvp, cnp);
228 	if (error) {
229 		UDEBUG(("dvp %p error %d flags %lx\n", dvp, error, cnp->cn_flags));
230 		*vpp = NULL;
231 		return (error);
232 	}
233 
234 	/*
235 	 * The parent directory will have been unlocked, unless lookup
236 	 * found the last component or if dvp == tdvp (tdvp must be locked).
237 	 *
238 	 * We want our dvp to remain locked and ref'd.  We also want tdvp
239 	 * to remain locked and ref'd.
240 	 */
241 	UDEBUG(("parentdir %p result %p flag %lx\n", dvp, tdvp, cnp->cn_flags));
242 
243 	if (dvp != tdvp && (cnp->cn_flags & ISLASTCN) == 0)
244 		vn_lock(dvp, LK_EXCLUSIVE | LK_RETRY, td);
245 
246 	/*
247 	 * Lastly check if the current node is a mount point in
248 	 * which case walk up the mount hierarchy making sure not to
249 	 * bump into the root of the mount tree (ie. dvp != udvp).
250 	 *
251 	 * We use dvp as a temporary variable here, it is no longer related
252 	 * to the dvp above.  However, we have to ensure that both *pdvp and
253 	 * tdvp are locked on return.
254 	 */
255 
256 	dvp = tdvp;
257 	while (
258 	    dvp != udvp &&
259 	    (dvp->v_type == VDIR) &&
260 	    (mp = dvp->v_mountedhere)
261 	) {
262 		int relock_pdvp = 0;
263 
264 		if (vfs_busy(mp, 0, 0, td))
265 			continue;
266 
267 		if (dvp == *pdvp)
268 			relock_pdvp = 1;
269 		vput(dvp);
270 		dvp = NULL;
271 		error = VFS_ROOT(mp, &dvp, td);
272 
273 		vfs_unbusy(mp, td);
274 
275 		if (relock_pdvp)
276 			vn_lock(*pdvp, LK_EXCLUSIVE | LK_RETRY, td);
277 
278 		if (error) {
279 			*vpp = NULL;
280 			return (error);
281 		}
282 	}
283 	*vpp = dvp;
284 	return (0);
285 }
286 
287 static int
288 union_lookup(ap)
289 	struct vop_lookup_args /* {
290 		struct vnodeop_desc *a_desc;
291 		struct vnode *a_dvp;
292 		struct vnode **a_vpp;
293 		struct componentname *a_cnp;
294 	} */ *ap;
295 {
296 	int error;
297 	int uerror, lerror;
298 	struct vnode *uppervp, *lowervp;
299 	struct vnode *upperdvp, *lowerdvp;
300 	struct vnode *dvp = ap->a_dvp;		/* starting dir */
301 	struct union_node *dun = VTOUNION(dvp);	/* associated union node */
302 	struct componentname *cnp = ap->a_cnp;
303 	struct thread *td = cnp->cn_thread;
304 	int lockparent = cnp->cn_flags & LOCKPARENT;
305 	struct union_mount *um = MOUNTTOUNIONMOUNT(dvp->v_mount);
306 	struct ucred *saved_cred = NULL;
307 	int iswhiteout;
308 	struct vattr va;
309 
310 	*ap->a_vpp = NULLVP;
311 
312 	/*
313 	 * Disallow write attempts to the filesystem mounted read-only.
314 	 */
315 	if ((cnp->cn_flags & ISLASTCN) &&
316 	    (dvp->v_mount->mnt_flag & MNT_RDONLY) &&
317 	    (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
318 		return (EROFS);
319 	}
320 
321 	/*
322 	 * For any lookups we do, always return with the parent locked.
323 	 */
324 	cnp->cn_flags |= LOCKPARENT;
325 
326 	lowerdvp = dun->un_lowervp;
327 	uppervp = NULLVP;
328 	lowervp = NULLVP;
329 	iswhiteout = 0;
330 
331 	uerror = ENOENT;
332 	lerror = ENOENT;
333 
334 	/*
335 	 * Get a private lock on uppervp and a reference, effectively
336 	 * taking it out of the union_node's control.
337 	 *
338 	 * We must lock upperdvp while holding our lock on dvp
339 	 * to avoid a deadlock.
340 	 */
341 	upperdvp = union_lock_upper(dun, td);
342 
343 	/*
344 	 * Do the lookup in the upper level.
345 	 * If that level consumes additional pathnames,
346 	 * then assume that something special is going
347 	 * on and just return that vnode.
348 	 */
349 	if (upperdvp != NULLVP) {
350 		/*
351 		 * We do not have to worry about the DOTDOT case, we've
352 		 * already unlocked dvp.
353 		 */
354 		UDEBUG(("A %p\n", upperdvp));
355 
356 		/*
357 		 * Do the lookup.   We must supply a locked and referenced
358 		 * upperdvp to the function and will get a new locked and
359 		 * referenced upperdvp back, with the old having been
360 		 * dereferenced.
361 		 *
362 		 * If an error is returned, uppervp will be NULLVP.  If no
363 		 * error occurs, uppervp will be the locked and referenced.
364 		 * Return vnode, or possibly NULL, depending on what is being
365 		 * requested.  It is possible that the returned uppervp
366 		 * will be the same as upperdvp.
367 		 */
368 		uerror = union_lookup1(um->um_uppervp, &upperdvp, &uppervp, cnp);
369 		UDEBUG((
370 		    "uerror %d upperdvp %p %d/%d, uppervp %p ref=%d/lck=%d\n",
371 		    uerror,
372 		    upperdvp,
373 		    vrefcnt(upperdvp),
374 		    VOP_ISLOCKED(upperdvp, NULL),
375 		    uppervp,
376 		    (uppervp ? vrefcnt(uppervp) : -99),
377 		    (uppervp ? VOP_ISLOCKED(uppervp, NULL) : -99)
378 		));
379 
380 		/*
381 		 * Disallow write attempts to the filesystem mounted read-only.
382 		 */
383 		if (uerror == EJUSTRETURN && (cnp->cn_flags & ISLASTCN) &&
384 		    (dvp->v_mount->mnt_flag & MNT_RDONLY) &&
385 		    (cnp->cn_nameiop == CREATE || cnp->cn_nameiop == RENAME)) {
386 			error = EROFS;
387 			goto out;
388 		}
389 
390 		/*
391 		 * Special case: If cn_consume != 0 then skip out.  The result
392 		 * of the lookup is transfered to our return variable.  If
393 		 * an error occured we have to throw away the results.
394 		 */
395 
396 		if (cnp->cn_consume != 0) {
397 			if ((error = uerror) == 0) {
398 				*ap->a_vpp = uppervp;
399 				uppervp = NULL;
400 			}
401 			goto out;
402 		}
403 
404 		/*
405 		 * Calculate whiteout, fall through.
406 		 */
407 
408 		if (uerror == ENOENT || uerror == EJUSTRETURN) {
409 			if (cnp->cn_flags & ISWHITEOUT) {
410 				iswhiteout = 1;
411 			} else if (lowerdvp != NULLVP) {
412 				int terror;
413 
414 				terror = VOP_GETATTR(upperdvp, &va,
415 					cnp->cn_cred, cnp->cn_thread);
416 				if (terror == 0 && (va.va_flags & OPAQUE))
417 					iswhiteout = 1;
418 			}
419 		}
420 	}
421 
422 	/*
423 	 * In a similar way to the upper layer, do the lookup
424 	 * in the lower layer.   This time, if there is some
425 	 * component magic going on, then vput whatever we got
426 	 * back from the upper layer and return the lower vnode
427 	 * instead.
428 	 */
429 
430 	if (lowerdvp != NULLVP && !iswhiteout) {
431 		int nameiop;
432 
433 		UDEBUG(("B %p\n", lowerdvp));
434 
435 		/*
436 		 * Force only LOOKUPs on the lower node, since
437 		 * we won't be making changes to it anyway.
438 		 */
439 		nameiop = cnp->cn_nameiop;
440 		cnp->cn_nameiop = LOOKUP;
441 		if (um->um_op == UNMNT_BELOW) {
442 			saved_cred = cnp->cn_cred;
443 			cnp->cn_cred = um->um_cred;
444 		}
445 
446 		/*
447 		 * We shouldn't have to worry about locking interactions
448 		 * between the lower layer and our union layer (w.r.t.
449 		 * `..' processing) because we don't futz with lowervp
450 		 * locks in the union-node instantiation code path.
451 		 *
452 		 * union_lookup1() requires lowervp to be locked on entry,
453 		 * and it will be unlocked on return.  The ref count will
454 		 * not change.  On return lowervp doesn't represent anything
455 		 * to us so we NULL it out.
456 		 */
457 		VREF(lowerdvp);
458 		vn_lock(lowerdvp, LK_EXCLUSIVE | LK_RETRY, td);
459 		lerror = union_lookup1(um->um_lowervp, &lowerdvp, &lowervp, cnp);
460 		if (lowerdvp == lowervp)
461 			vrele(lowerdvp);
462 		else
463 			vput(lowerdvp);
464 		lowerdvp = NULL;	/* lowerdvp invalid after vput */
465 
466 		if (um->um_op == UNMNT_BELOW)
467 			cnp->cn_cred = saved_cred;
468 		cnp->cn_nameiop = nameiop;
469 
470 		if (cnp->cn_consume != 0 || lerror == EACCES) {
471 			if ((error = lerror) == 0) {
472 				*ap->a_vpp = lowervp;
473 				lowervp = NULL;
474 			}
475 			goto out;
476 		}
477 	} else {
478 		UDEBUG(("C %p\n", lowerdvp));
479 		if ((cnp->cn_flags & ISDOTDOT) && dun->un_pvp != NULLVP) {
480 			if ((lowervp = LOWERVP(dun->un_pvp)) != NULL) {
481 				VREF(lowervp);
482 				vn_lock(lowervp, LK_EXCLUSIVE | LK_RETRY, td);
483 				lerror = 0;
484 			}
485 		}
486 	}
487 
488 	/*
489 	 * Ok.  Now we have uerror, uppervp, upperdvp, lerror, and lowervp.
490 	 *
491 	 * 1. If both layers returned an error, select the upper layer.
492 	 *
493 	 * 2. If the upper layer failed and the bottom layer succeeded,
494 	 *    two subcases occur:
495 	 *
496 	 *	a.  The bottom vnode is not a directory, in which case
497 	 *	    just return a new union vnode referencing an
498 	 *	    empty top layer and the existing bottom layer.
499 	 *
500 	 *	b.  The bottom vnode is a directory, in which case
501 	 *	    create a new directory in the top layer and
502 	 *	    and fall through to case 3.
503 	 *
504 	 * 3. If the top layer succeeded, then return a new union
505 	 *    vnode referencing whatever the new top layer and
506 	 *    whatever the bottom layer returned.
507 	 */
508 
509 	/* case 1. */
510 	if ((uerror != 0) && (lerror != 0)) {
511 		error = uerror;
512 		goto out;
513 	}
514 
515 	/* case 2. */
516 	if (uerror != 0 /* && (lerror == 0) */ ) {
517 		if (lowervp->v_type == VDIR) { /* case 2b. */
518 			KASSERT(uppervp == NULL, ("uppervp unexpectedly non-NULL"));
519 			/*
520 			 * Oops, uppervp has a problem, we may have to shadow.
521 			 */
522 			uerror = union_mkshadow(um, upperdvp, cnp, &uppervp);
523 			if (uerror) {
524 				error = uerror;
525 				goto out;
526 			}
527 		}
528 	}
529 
530 	/*
531 	 * Must call union_allocvp() with both the upper and lower vnodes
532 	 * referenced and the upper vnode locked.   ap->a_vpp is returned
533 	 * referenced and locked.  lowervp, uppervp, and upperdvp are
534 	 * absorbed by union_allocvp() whether it succeeds or fails.
535 	 *
536 	 * upperdvp is the parent directory of uppervp which may be
537 	 * different, depending on the path, from dvp->un_uppervp.  That's
538 	 * why it is a separate argument.  Note that it must be unlocked.
539 	 *
540 	 * dvp must be locked on entry to the call and will be locked on
541 	 * return.
542 	 */
543 
544 	if (uppervp && uppervp != upperdvp)
545 		VOP_UNLOCK(uppervp, 0, td);
546 	if (lowervp)
547 		VOP_UNLOCK(lowervp, 0, td);
548 	if (upperdvp)
549 		VOP_UNLOCK(upperdvp, 0, td);
550 
551 	error = union_allocvp(ap->a_vpp, dvp->v_mount, dvp, upperdvp, cnp,
552 			      uppervp, lowervp, 1);
553 
554 	UDEBUG(("Create %p = %p %p refs=%d\n", *ap->a_vpp, uppervp, lowervp, (*ap->a_vpp) ? vrefcnt(*ap->a_vpp) : -99));
555 
556 	uppervp = NULL;
557 	upperdvp = NULL;
558 	lowervp = NULL;
559 
560 	/*
561 	 *	Termination Code
562 	 *
563 	 *	- put away any extra junk laying around.  Note that lowervp
564 	 *	  (if not NULL) will never be the same as *ap->a_vp and
565 	 *	  neither will uppervp, because when we set that state we
566 	 *	  NULL-out lowervp or uppervp.  On the otherhand, upperdvp
567 	 *	  may match uppervp or *ap->a_vpp.
568 	 *
569 	 *	- relock/unlock dvp if appropriate.
570 	 */
571 
572 out:
573 	if (upperdvp) {
574 		if (upperdvp == uppervp || upperdvp == *ap->a_vpp)
575 			vrele(upperdvp);
576 		else
577 			vput(upperdvp);
578 	}
579 
580 	if (uppervp)
581 		vput(uppervp);
582 
583 	if (lowervp)
584 		vput(lowervp);
585 
586 	/*
587 	 * Restore LOCKPARENT state
588 	 */
589 
590 	if (!lockparent)
591 		cnp->cn_flags &= ~LOCKPARENT;
592 
593 	UDEBUG(("Out %d vpp %p/%d lower %p upper %p\n", error, *ap->a_vpp,
594 		((*ap->a_vpp) ? vrefcnt(*ap->a_vpp) : -99),
595 		lowervp, uppervp));
596 
597 	if (error == 0 || error == EJUSTRETURN) {
598 		/*
599 		 * dvp lock state, determine whether to relock dvp.
600 		 * We are expected to unlock dvp unless:
601 		 *
602 		 *	- there was an error (other than EJUSTRETURN), or
603 		 *	- we hit the last component and lockparent is true
604 		 */
605 		if (*ap->a_vpp != dvp) {
606 			if (!lockparent || (cnp->cn_flags & ISLASTCN) == 0)
607 				VOP_UNLOCK(dvp, 0, td);
608 		}
609 
610 		if (cnp->cn_namelen == 1 &&
611 		    cnp->cn_nameptr[0] == '.' &&
612 		    *ap->a_vpp != dvp) {
613 #ifdef	DIAGNOSTIC
614 			vprint("union_lookup: vp", *ap->a_vpp);
615 			vprint("union_lookup: dvp", dvp);
616 #endif
617 			panic("union_lookup returning . (%p) != startdir (%p)",
618 			    *ap->a_vpp, dvp);
619 		}
620 	}
621 
622 	return (error);
623 }
624 
625 /*
626  * 	union_create:
627  *
628  * a_dvp is locked on entry and remains locked on return.  a_vpp is returned
629  * locked if no error occurs, otherwise it is garbage.
630  */
631 
632 static int
633 union_create(ap)
634 	struct vop_create_args /* {
635 		struct vnode *a_dvp;
636 		struct vnode **a_vpp;
637 		struct componentname *a_cnp;
638 		struct vattr *a_vap;
639 	} */ *ap;
640 {
641 	struct union_node *dun = VTOUNION(ap->a_dvp);
642 	struct componentname *cnp = ap->a_cnp;
643 	struct thread *td = cnp->cn_thread;
644 	struct vnode *dvp;
645 	int error = EROFS;
646 
647 	if ((dvp = union_lock_upper(dun, td)) != NULL) {
648 		struct vnode *vp;
649 		struct mount *mp;
650 
651 		error = VOP_CREATE(dvp, &vp, cnp, ap->a_vap);
652 		if (error == 0) {
653 			mp = ap->a_dvp->v_mount;
654 			VOP_UNLOCK(vp, 0, td);
655 			UDEBUG(("ALLOCVP-1 FROM %p REFS %d\n", vp, vrefcnt(vp)));
656 			error = union_allocvp(ap->a_vpp, mp, NULLVP, NULLVP,
657 				cnp, vp, NULLVP, 1);
658 			UDEBUG(("ALLOCVP-2B FROM %p REFS %d\n", *ap->a_vpp, vrefcnt(vp)));
659 		}
660 		union_unlock_upper(dvp, td);
661 	}
662 	return (error);
663 }
664 
665 static int
666 union_whiteout(ap)
667 	struct vop_whiteout_args /* {
668 		struct vnode *a_dvp;
669 		struct componentname *a_cnp;
670 		int a_flags;
671 	} */ *ap;
672 {
673 	struct union_node *un = VTOUNION(ap->a_dvp);
674 	struct componentname *cnp = ap->a_cnp;
675 	struct vnode *uppervp;
676 	int error;
677 
678 	switch (ap->a_flags) {
679 	case CREATE:
680 	case DELETE:
681 		uppervp = union_lock_upper(un, cnp->cn_thread);
682 		if (uppervp != NULLVP) {
683 			error = VOP_WHITEOUT(un->un_uppervp, cnp, ap->a_flags);
684 			union_unlock_upper(uppervp, cnp->cn_thread);
685 		} else
686 			error = EOPNOTSUPP;
687 		break;
688 	case LOOKUP:
689 		error = EOPNOTSUPP;
690 		break;
691 	default:
692 		panic("union_whiteout: unknown op");
693 	}
694 	return (error);
695 }
696 
697 /*
698  * 	union_mknod:
699  *
700  *	a_dvp is locked on entry and should remain locked on return.
701  *	a_vpp is garbagre whether an error occurs or not.
702  */
703 
704 static int
705 union_mknod(ap)
706 	struct vop_mknod_args /* {
707 		struct vnode *a_dvp;
708 		struct vnode **a_vpp;
709 		struct componentname *a_cnp;
710 		struct vattr *a_vap;
711 	} */ *ap;
712 {
713 	struct union_node *dun = VTOUNION(ap->a_dvp);
714 	struct componentname *cnp = ap->a_cnp;
715 	struct vnode *dvp;
716 	int error = EROFS;
717 
718 	if ((dvp = union_lock_upper(dun, cnp->cn_thread)) != NULL) {
719 		error = VOP_MKNOD(dvp, ap->a_vpp, cnp, ap->a_vap);
720 		union_unlock_upper(dvp, cnp->cn_thread);
721 	}
722 	return (error);
723 }
724 
725 /*
726  *	union_open:
727  *
728  *	run open VOP.  When opening the underlying vnode we have to mimic
729  *	vn_open().  What we *really* need to do to avoid screwups if the
730  *	open semantics change is to call vn_open().  For example, ufs blows
731  *	up if you open a file but do not vmio it prior to writing.
732  */
733 
734 static int
735 union_open(ap)
736 	struct vop_open_args /* {
737 		struct vnodeop_desc *a_desc;
738 		struct vnode *a_vp;
739 		int a_mode;
740 		struct ucred *a_cred;
741 		struct thread *a_td;
742 	} */ *ap;
743 {
744 	struct union_node *un = VTOUNION(ap->a_vp);
745 	struct vnode *tvp;
746 	int mode = ap->a_mode;
747 	struct ucred *cred = ap->a_cred;
748 	struct thread *td = ap->a_td;
749 	int error = 0;
750 	int tvpisupper = 1;
751 
752 	/*
753 	 * If there is an existing upper vp then simply open that.
754 	 * The upper vp takes precedence over the lower vp.  When opening
755 	 * a lower vp for writing copy it to the uppervp and then open the
756 	 * uppervp.
757 	 *
758 	 * At the end of this section tvp will be left locked.
759 	 */
760 	if ((tvp = union_lock_upper(un, td)) == NULLVP) {
761 		/*
762 		 * If the lower vnode is being opened for writing, then
763 		 * copy the file contents to the upper vnode and open that,
764 		 * otherwise can simply open the lower vnode.
765 		 */
766 		tvp = un->un_lowervp;
767 		if ((ap->a_mode & FWRITE) && (tvp->v_type == VREG)) {
768 			int docopy = !(mode & O_TRUNC);
769 			error = union_copyup(un, docopy, cred, td);
770 			tvp = union_lock_upper(un, td);
771 		} else {
772 			un->un_openl++;
773 			VREF(tvp);
774 			vn_lock(tvp, LK_EXCLUSIVE | LK_RETRY, td);
775 			tvpisupper = 0;
776 		}
777 	}
778 
779 	/*
780 	 * We are holding the correct vnode, open it.
781 	 */
782 
783 	if (error == 0)
784 		error = VOP_OPEN(tvp, mode, cred, td, -1);
785 
786 	/*
787 	 * This is absolutely necessary or UFS will blow up.
788 	 */
789         if (error == 0 && vn_canvmio(tvp) == TRUE) {
790                 error = vfs_object_create(tvp, td, cred);
791         }
792 
793 	/*
794 	 * Release any locks held.
795 	 */
796 	if (tvpisupper) {
797 		if (tvp)
798 			union_unlock_upper(tvp, td);
799 	} else {
800 		vput(tvp);
801 	}
802 	return (error);
803 }
804 
805 /*
806  *	union_close:
807  *
808  *	It is unclear whether a_vp is passed locked or unlocked.  Whatever
809  *	the case we do not change it.
810  */
811 
812 static int
813 union_close(ap)
814 	struct vop_close_args /* {
815 		struct vnode *a_vp;
816 		int  a_fflag;
817 		struct ucred *a_cred;
818 		struct thread *a_td;
819 	} */ *ap;
820 {
821 	struct union_node *un = VTOUNION(ap->a_vp);
822 	struct vnode *vp;
823 
824 	if ((vp = un->un_uppervp) == NULLVP) {
825 #ifdef UNION_DIAGNOSTIC
826 		if (un->un_openl <= 0)
827 			panic("union: un_openl cnt");
828 #endif
829 		--un->un_openl;
830 		vp = un->un_lowervp;
831 	}
832 	ap->a_vp = vp;
833 	return (VCALL(vp, VOFFSET(vop_close), ap));
834 }
835 
836 /*
837  * Check access permission on the union vnode.
838  * The access check being enforced is to check
839  * against both the underlying vnode, and any
840  * copied vnode.  This ensures that no additional
841  * file permissions are given away simply because
842  * the user caused an implicit file copy.
843  */
844 static int
845 union_access(ap)
846 	struct vop_access_args /* {
847 		struct vnodeop_desc *a_desc;
848 		struct vnode *a_vp;
849 		int a_mode;
850 		struct ucred *a_cred;
851 		struct thread *a_td;
852 	} */ *ap;
853 {
854 	struct union_node *un = VTOUNION(ap->a_vp);
855 	struct thread *td = ap->a_td;
856 	int error = EACCES;
857 	struct vnode *vp;
858 
859 	/*
860 	 * Disallow write attempts on filesystems mounted read-only.
861 	 */
862 	if ((ap->a_mode & VWRITE) &&
863 	    (ap->a_vp->v_mount->mnt_flag & MNT_RDONLY)) {
864 		switch (ap->a_vp->v_type) {
865 		case VREG:
866 		case VDIR:
867 		case VLNK:
868 			return (EROFS);
869 		default:
870 			break;
871 		}
872 	}
873 
874 	if ((vp = union_lock_upper(un, td)) != NULLVP) {
875 		ap->a_vp = vp;
876 		error = VCALL(vp, VOFFSET(vop_access), ap);
877 		union_unlock_upper(vp, td);
878 		return(error);
879 	}
880 
881 	if ((vp = un->un_lowervp) != NULLVP) {
882 		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
883 		ap->a_vp = vp;
884 
885 		/*
886 		 * Remove VWRITE from a_mode if our mount point is RW, because
887 		 * we want to allow writes and lowervp may be read-only.
888 		 */
889 		if ((un->un_vnode->v_mount->mnt_flag & MNT_RDONLY) == 0)
890 			ap->a_mode &= ~VWRITE;
891 
892 		error = VCALL(vp, VOFFSET(vop_access), ap);
893 		if (error == 0) {
894 			struct union_mount *um;
895 
896 			um = MOUNTTOUNIONMOUNT(un->un_vnode->v_mount);
897 
898 			if (um->um_op == UNMNT_BELOW) {
899 				ap->a_cred = um->um_cred;
900 				error = VCALL(vp, VOFFSET(vop_access), ap);
901 			}
902 		}
903 		VOP_UNLOCK(vp, 0, td);
904 	}
905 	return(error);
906 }
907 
908 /*
909  * We handle getattr only to change the fsid and
910  * track object sizes
911  *
912  * It's not clear whether VOP_GETATTR is to be
913  * called with the vnode locked or not.  stat() calls
914  * it with (vp) locked, and fstat() calls it with
915  * (vp) unlocked.
916  *
917  * Because of this we cannot use our normal locking functions
918  * if we do not intend to lock the main a_vp node.  At the moment
919  * we are running without any specific locking at all, but beware
920  * to any programmer that care must be taken if locking is added
921  * to this function.
922  */
923 
924 static int
925 union_getattr(ap)
926 	struct vop_getattr_args /* {
927 		struct vnode *a_vp;
928 		struct vattr *a_vap;
929 		struct ucred *a_cred;
930 		struct thread *a_td;
931 	} */ *ap;
932 {
933 	int error;
934 	struct union_node *un = VTOUNION(ap->a_vp);
935 	struct vnode *vp;
936 	struct vattr *vap;
937 	struct vattr va;
938 
939 	/*
940 	 * Some programs walk the filesystem hierarchy by counting
941 	 * links to directories to avoid stat'ing all the time.
942 	 * This means the link count on directories needs to be "correct".
943 	 * The only way to do that is to call getattr on both layers
944 	 * and fix up the link count.  The link count will not necessarily
945 	 * be accurate but will be large enough to defeat the tree walkers.
946 	 */
947 
948 	vap = ap->a_vap;
949 
950 	if ((vp = un->un_uppervp) != NULLVP) {
951 		error = VOP_GETATTR(vp, vap, ap->a_cred, ap->a_td);
952 		if (error)
953 			return (error);
954 		/* XXX isn't this dangerous without a lock? */
955 		union_newsize(ap->a_vp, vap->va_size, VNOVAL);
956 	}
957 
958 	if (vp == NULLVP) {
959 		vp = un->un_lowervp;
960 	} else if (vp->v_type == VDIR && un->un_lowervp != NULLVP) {
961 		vp = un->un_lowervp;
962 		vap = &va;
963 	} else {
964 		vp = NULLVP;
965 	}
966 
967 	if (vp != NULLVP) {
968 		error = VOP_GETATTR(vp, vap, ap->a_cred, ap->a_td);
969 		if (error)
970 			return (error);
971 		/* XXX isn't this dangerous without a lock? */
972 		union_newsize(ap->a_vp, VNOVAL, vap->va_size);
973 	}
974 
975 	if ((vap != ap->a_vap) && (vap->va_type == VDIR))
976 		ap->a_vap->va_nlink += vap->va_nlink;
977 	return (0);
978 }
979 
980 static int
981 union_setattr(ap)
982 	struct vop_setattr_args /* {
983 		struct vnode *a_vp;
984 		struct vattr *a_vap;
985 		struct ucred *a_cred;
986 		struct thread *a_td;
987 	} */ *ap;
988 {
989 	struct union_node *un = VTOUNION(ap->a_vp);
990 	struct thread *td = ap->a_td;
991 	struct vattr *vap = ap->a_vap;
992 	struct vnode *uppervp;
993 	int error;
994 
995 	/*
996 	 * Disallow write attempts on filesystems mounted read-only.
997 	 */
998 	if ((ap->a_vp->v_mount->mnt_flag & MNT_RDONLY) &&
999 	    (vap->va_flags != VNOVAL || vap->va_uid != (uid_t)VNOVAL ||
1000 	     vap->va_gid != (gid_t)VNOVAL || vap->va_atime.tv_sec != VNOVAL ||
1001 	     vap->va_mtime.tv_sec != VNOVAL ||
1002 	     vap->va_mode != (mode_t)VNOVAL)) {
1003 		return (EROFS);
1004 	}
1005 
1006 	/*
1007 	 * Handle case of truncating lower object to zero size
1008 	 * by creating a zero length upper object.  This is to
1009 	 * handle the case of open with O_TRUNC and O_CREAT.
1010 	 */
1011 	if (un->un_uppervp == NULLVP && (un->un_lowervp->v_type == VREG)) {
1012 		error = union_copyup(un, (ap->a_vap->va_size != 0),
1013 			    ap->a_cred, ap->a_td);
1014 		if (error)
1015 			return (error);
1016 	}
1017 
1018 	/*
1019 	 * Try to set attributes in upper layer,
1020 	 * otherwise return read-only filesystem error.
1021 	 */
1022 	error = EROFS;
1023 	if ((uppervp = union_lock_upper(un, td)) != NULLVP) {
1024 		error = VOP_SETATTR(un->un_uppervp, ap->a_vap,
1025 					ap->a_cred, ap->a_td);
1026 		if ((error == 0) && (ap->a_vap->va_size != VNOVAL))
1027 			union_newsize(ap->a_vp, ap->a_vap->va_size, VNOVAL);
1028 		union_unlock_upper(uppervp, td);
1029 	}
1030 	return (error);
1031 }
1032 
1033 static int
1034 union_read(ap)
1035 	struct vop_read_args /* {
1036 		struct vnode *a_vp;
1037 		struct uio *a_uio;
1038 		int  a_ioflag;
1039 		struct ucred *a_cred;
1040 	} */ *ap;
1041 {
1042 	struct union_node *un = VTOUNION(ap->a_vp);
1043 	struct thread *td = ap->a_uio->uio_td;
1044 	struct vnode *uvp;
1045 	int error;
1046 
1047 	uvp = union_lock_other(un, td);
1048 	KASSERT(uvp != NULL, ("union_read: backing vnode missing!"));
1049 
1050 	error = VOP_READ(uvp, ap->a_uio, ap->a_ioflag, ap->a_cred);
1051 	union_unlock_other(uvp, td);
1052 
1053 	/*
1054 	 * XXX
1055 	 * Perhaps the size of the underlying object has changed under
1056 	 * our feet.  Take advantage of the offset information present
1057 	 * in the uio structure.
1058 	 */
1059 	if (error == 0) {
1060 		struct union_node *un = VTOUNION(ap->a_vp);
1061 		off_t cur = ap->a_uio->uio_offset;
1062 
1063 		if (uvp == un->un_uppervp) {
1064 			if (cur > un->un_uppersz)
1065 				union_newsize(ap->a_vp, cur, VNOVAL);
1066 		} else {
1067 			if (cur > un->un_lowersz)
1068 				union_newsize(ap->a_vp, VNOVAL, cur);
1069 		}
1070 	}
1071 	return (error);
1072 }
1073 
1074 static int
1075 union_write(ap)
1076 	struct vop_read_args /* {
1077 		struct vnode *a_vp;
1078 		struct uio *a_uio;
1079 		int  a_ioflag;
1080 		struct ucred *a_cred;
1081 	} */ *ap;
1082 {
1083 	struct union_node *un = VTOUNION(ap->a_vp);
1084 	struct thread *td = ap->a_uio->uio_td;
1085 	struct vnode *uppervp;
1086 	int error;
1087 
1088 	if ((uppervp = union_lock_upper(un, td)) == NULLVP)
1089 		panic("union: missing upper layer in write");
1090 
1091 	error = VOP_WRITE(uppervp, ap->a_uio, ap->a_ioflag, ap->a_cred);
1092 
1093 	/*
1094 	 * The size of the underlying object may be changed by the
1095 	 * write.
1096 	 */
1097 	if (error == 0) {
1098 		off_t cur = ap->a_uio->uio_offset;
1099 
1100 		if (cur > un->un_uppersz)
1101 			union_newsize(ap->a_vp, cur, VNOVAL);
1102 	}
1103 	union_unlock_upper(uppervp, td);
1104 	return (error);
1105 }
1106 
1107 static int
1108 union_lease(ap)
1109 	struct vop_lease_args /* {
1110 		struct vnode *a_vp;
1111 		struct thread *a_td;
1112 		struct ucred *a_cred;
1113 		int a_flag;
1114 	} */ *ap;
1115 {
1116 	struct vnode *ovp = OTHERVP(ap->a_vp);
1117 
1118 	ap->a_vp = ovp;
1119 	return (VCALL(ovp, VOFFSET(vop_lease), ap));
1120 }
1121 
1122 static int
1123 union_ioctl(ap)
1124 	struct vop_ioctl_args /* {
1125 		struct vnode *a_vp;
1126 		u_long  a_command;
1127 		caddr_t  a_data;
1128 		int  a_fflag;
1129 		struct ucred *a_cred;
1130 		struct thread *a_td;
1131 	} */ *ap;
1132 {
1133 	struct vnode *ovp = OTHERVP(ap->a_vp);
1134 
1135 	ap->a_vp = ovp;
1136 	return (VCALL(ovp, VOFFSET(vop_ioctl), ap));
1137 }
1138 
1139 static int
1140 union_poll(ap)
1141 	struct vop_poll_args /* {
1142 		struct vnode *a_vp;
1143 		int  a_events;
1144 		struct ucred *a_cred;
1145 		struct thread *a_td;
1146 	} */ *ap;
1147 {
1148 	struct vnode *ovp = OTHERVP(ap->a_vp);
1149 
1150 	ap->a_vp = ovp;
1151 	return (VCALL(ovp, VOFFSET(vop_poll), ap));
1152 }
1153 
1154 static int
1155 union_revoke(ap)
1156 	struct vop_revoke_args /* {
1157 		struct vnode *a_vp;
1158 		int a_flags;
1159 		struct thread *a_td;
1160 	} */ *ap;
1161 {
1162 	struct vnode *vp = ap->a_vp;
1163 
1164 	if (UPPERVP(vp))
1165 		VOP_REVOKE(UPPERVP(vp), ap->a_flags);
1166 	if (LOWERVP(vp))
1167 		VOP_REVOKE(LOWERVP(vp), ap->a_flags);
1168 	vgone(vp);
1169 	return (0);
1170 }
1171 
1172 static int
1173 union_fsync(ap)
1174 	struct vop_fsync_args /* {
1175 		struct vnode *a_vp;
1176 		struct ucred *a_cred;
1177 		int  a_waitfor;
1178 		struct thread *a_td;
1179 	} */ *ap;
1180 {
1181 	int error = 0;
1182 	struct thread *td = ap->a_td;
1183 	struct vnode *targetvp;
1184 	struct union_node *un = VTOUNION(ap->a_vp);
1185 
1186 	if ((targetvp = union_lock_other(un, td)) != NULLVP) {
1187 		error = VOP_FSYNC(targetvp, ap->a_cred, ap->a_waitfor, td);
1188 		union_unlock_other(targetvp, td);
1189 	}
1190 
1191 	return (error);
1192 }
1193 
1194 /*
1195  *	union_remove:
1196  *
1197  *	Remove the specified cnp.  The dvp and vp are passed to us locked
1198  *	and must remain locked on return.
1199  */
1200 
1201 static int
1202 union_remove(ap)
1203 	struct vop_remove_args /* {
1204 		struct vnode *a_dvp;
1205 		struct vnode *a_vp;
1206 		struct componentname *a_cnp;
1207 	} */ *ap;
1208 {
1209 	struct union_node *dun = VTOUNION(ap->a_dvp);
1210 	struct union_node *un = VTOUNION(ap->a_vp);
1211 	struct componentname *cnp = ap->a_cnp;
1212 	struct thread *td = cnp->cn_thread;
1213 	struct vnode *uppervp;
1214 	struct vnode *upperdvp;
1215 	int error;
1216 
1217 	if ((upperdvp = union_lock_upper(dun, td)) == NULLVP)
1218 		panic("union remove: null upper vnode");
1219 
1220 	if ((uppervp = union_lock_upper(un, td)) != NULLVP) {
1221 		if (union_dowhiteout(un, cnp->cn_cred, td))
1222 			cnp->cn_flags |= DOWHITEOUT;
1223 		if (cnp->cn_flags & DOWHITEOUT)		/* XXX fs corruption */
1224 			error = EOPNOTSUPP;
1225 		else
1226 			error = VOP_REMOVE(upperdvp, uppervp, cnp);
1227 		if (!error)
1228 			union_removed_upper(un);
1229 		union_unlock_upper(uppervp, td);
1230 	} else {
1231 		error = union_mkwhiteout(
1232 			    MOUNTTOUNIONMOUNT(ap->a_dvp->v_mount),
1233 			    upperdvp, ap->a_cnp, un->un_path);
1234 	}
1235 	union_unlock_upper(upperdvp, td);
1236 	return (error);
1237 }
1238 
1239 /*
1240  *	union_link:
1241  *
1242  *	tdvp and vp will be locked on entry.
1243  *	tdvp and vp should remain locked on return.
1244  */
1245 
1246 static int
1247 union_link(ap)
1248 	struct vop_link_args /* {
1249 		struct vnode *a_tdvp;
1250 		struct vnode *a_vp;
1251 		struct componentname *a_cnp;
1252 	} */ *ap;
1253 {
1254 	struct componentname *cnp = ap->a_cnp;
1255 	struct thread *td = cnp->cn_thread;
1256 	struct union_node *dun = VTOUNION(ap->a_tdvp);
1257 	struct vnode *vp;
1258 	struct vnode *tdvp;
1259 	int error = 0;
1260 
1261 	if (ap->a_tdvp->v_op != ap->a_vp->v_op) {
1262 		vp = ap->a_vp;
1263 	} else {
1264 		struct union_node *tun = VTOUNION(ap->a_vp);
1265 
1266 		if (tun->un_uppervp == NULLVP) {
1267 #if 0
1268 			if (dun->un_uppervp == tun->un_dirvp) {
1269 				if (dun->un_flags & UN_ULOCK) {
1270 					dun->un_flags &= ~UN_ULOCK;
1271 					VOP_UNLOCK(dun->un_uppervp, 0, td);
1272 				}
1273 			}
1274 #endif
1275 			error = union_copyup(tun, 1, cnp->cn_cred, td);
1276 #if 0
1277 			if (dun->un_uppervp == tun->un_dirvp) {
1278 				vn_lock(dun->un_uppervp,
1279 					    LK_EXCLUSIVE | LK_RETRY, td);
1280 				dun->un_flags |= UN_ULOCK;
1281 			}
1282 #endif
1283 			if (error)
1284 				return (error);
1285 		}
1286 		vp = tun->un_uppervp;
1287 		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
1288 	}
1289 
1290 	/*
1291 	 * Make sure upper is locked, then unlock the union directory we were
1292 	 * called with to avoid a deadlock while we are calling VOP_LINK() on
1293 	 * the upper (with tdvp locked and vp not locked).  Our ap->a_tdvp
1294 	 * is expected to be locked on return.
1295 	 */
1296 
1297 	if ((tdvp = union_lock_upper(dun, td)) == NULLVP)
1298 		return (EROFS);
1299 
1300 	VOP_UNLOCK(ap->a_tdvp, 0, td);		/* unlock calling node */
1301 	error = VOP_LINK(tdvp, vp, cnp);	/* call link on upper */
1302 
1303 	/*
1304 	 * Unlock tun->un_uppervp if we locked it above.
1305 	 */
1306 	if (ap->a_tdvp->v_op == ap->a_vp->v_op)
1307 		VOP_UNLOCK(vp, 0, td);
1308 	/*
1309 	 * We have to unlock tdvp prior to relocking our calling node in
1310 	 * order to avoid a deadlock.  We also have to unlock ap->a_vp
1311 	 * before relocking the directory, but then we have to relock
1312 	 * ap->a_vp as our caller expects.
1313 	 */
1314 	VOP_UNLOCK(ap->a_vp, 0, td);
1315 	union_unlock_upper(tdvp, td);
1316 	vn_lock(ap->a_tdvp, LK_EXCLUSIVE | LK_RETRY, td);
1317 	vn_lock(ap->a_vp, LK_EXCLUSIVE | LK_RETRY, td);
1318 	return (error);
1319 }
1320 
1321 static int
1322 union_rename(ap)
1323 	struct vop_rename_args  /* {
1324 		struct vnode *a_fdvp;
1325 		struct vnode *a_fvp;
1326 		struct componentname *a_fcnp;
1327 		struct vnode *a_tdvp;
1328 		struct vnode *a_tvp;
1329 		struct componentname *a_tcnp;
1330 	} */ *ap;
1331 {
1332 	int error;
1333 	struct vnode *fdvp = ap->a_fdvp;
1334 	struct vnode *fvp = ap->a_fvp;
1335 	struct vnode *tdvp = ap->a_tdvp;
1336 	struct vnode *tvp = ap->a_tvp;
1337 
1338 	/*
1339 	 * Figure out what fdvp to pass to our upper or lower vnode.  If we
1340 	 * replace the fdvp, release the original one and ref the new one.
1341 	 */
1342 
1343 	if (fdvp->v_op == union_vnodeop_p) {	/* always true */
1344 		struct union_node *un = VTOUNION(fdvp);
1345 		if (un->un_uppervp == NULLVP) {
1346 			/*
1347 			 * this should never happen in normal
1348 			 * operation but might if there was
1349 			 * a problem creating the top-level shadow
1350 			 * directory.
1351 			 */
1352 			error = EXDEV;
1353 			goto bad;
1354 		}
1355 		fdvp = un->un_uppervp;
1356 		VREF(fdvp);
1357 		vrele(ap->a_fdvp);
1358 	}
1359 
1360 	/*
1361 	 * Figure out what fvp to pass to our upper or lower vnode.  If we
1362 	 * replace the fvp, release the original one and ref the new one.
1363 	 */
1364 
1365 	if (fvp->v_op == union_vnodeop_p) {	/* always true */
1366 		struct union_node *un = VTOUNION(fvp);
1367 #if 0
1368 		struct union_mount *um = MOUNTTOUNIONMOUNT(fvp->v_mount);
1369 #endif
1370 
1371 		if (un->un_uppervp == NULLVP) {
1372 			switch(fvp->v_type) {
1373 			case VREG:
1374 				vn_lock(un->un_vnode, LK_EXCLUSIVE | LK_RETRY, ap->a_fcnp->cn_thread);
1375 				error = union_copyup(un, 1, ap->a_fcnp->cn_cred, ap->a_fcnp->cn_thread);
1376 				VOP_UNLOCK(un->un_vnode, 0, ap->a_fcnp->cn_thread);
1377 				if (error)
1378 					goto bad;
1379 				break;
1380 			case VDIR:
1381 				/*
1382 				 * XXX not yet.
1383 				 *
1384 				 * There is only one way to rename a directory
1385 				 * based in the lowervp, and that is to copy
1386 				 * the entire directory hierarchy.  Otherwise
1387 				 * it would not last across a reboot.
1388 				 */
1389 #if 0
1390 				vrele(fvp);
1391 				fvp = NULL;
1392 				vn_lock(fdvp, LK_EXCLUSIVE | LK_RETRY, ap->a_fcnp->cn_thread);
1393 				error = union_mkshadow(um, fdvp,
1394 					    ap->a_fcnp, &un->un_uppervp);
1395 				VOP_UNLOCK(fdvp, 0, ap->a_fcnp->cn_thread);
1396 				if (un->un_uppervp)
1397 					VOP_UNLOCK(un->un_uppervp, 0, ap->a_fcnp->cn_thread);
1398 				if (error)
1399 					goto bad;
1400 				break;
1401 #endif
1402 			default:
1403 				error = EXDEV;
1404 				goto bad;
1405 			}
1406 		}
1407 
1408 		if (un->un_lowervp != NULLVP)
1409 			ap->a_fcnp->cn_flags |= DOWHITEOUT;
1410 		fvp = un->un_uppervp;
1411 		VREF(fvp);
1412 		vrele(ap->a_fvp);
1413 	}
1414 
1415 	/*
1416 	 * Figure out what tdvp (destination directory) to pass to the
1417 	 * lower level.  If we replace it with uppervp, we need to vput the
1418 	 * old one.  The exclusive lock is transfered to what we will pass
1419 	 * down in the VOP_RENAME() and we replace uppervp with a simple
1420 	 * reference.
1421 	 */
1422 
1423 	if (tdvp->v_op == union_vnodeop_p) {
1424 		struct union_node *un = VTOUNION(tdvp);
1425 
1426 		if (un->un_uppervp == NULLVP) {
1427 			/*
1428 			 * This should never happen in normal
1429 			 * operation but might if there was
1430 			 * a problem creating the top-level shadow
1431 			 * directory.
1432 			 */
1433 			error = EXDEV;
1434 			goto bad;
1435 		}
1436 
1437 		/*
1438 		 * New tdvp is a lock and reference on uppervp.
1439 		 * Put away the old tdvp.
1440 		 */
1441 		tdvp = union_lock_upper(un, ap->a_tcnp->cn_thread);
1442 		vput(ap->a_tdvp);
1443 	}
1444 
1445 	/*
1446 	 * Figure out what tvp (destination file) to pass to the
1447 	 * lower level.
1448 	 *
1449 	 * If the uppervp file does not exist, put away the (wrong)
1450 	 * file and change tvp to NULL.
1451 	 */
1452 
1453 	if (tvp != NULLVP && tvp->v_op == union_vnodeop_p) {
1454 		struct union_node *un = VTOUNION(tvp);
1455 
1456 		tvp = union_lock_upper(un, ap->a_tcnp->cn_thread);
1457 		vput(ap->a_tvp);
1458 		/* note: tvp may be NULL */
1459 	}
1460 
1461 	/*
1462 	 * VOP_RENAME() releases/vputs prior to returning, so we have no
1463 	 * cleanup to do.
1464 	 */
1465 
1466 	return (VOP_RENAME(fdvp, fvp, ap->a_fcnp, tdvp, tvp, ap->a_tcnp));
1467 
1468 	/*
1469 	 * Error.  We still have to release / vput the various elements.
1470 	 */
1471 
1472 bad:
1473 	vrele(fdvp);
1474 	if (fvp)
1475 		vrele(fvp);
1476 	vput(tdvp);
1477 	if (tvp != NULLVP) {
1478 		if (tvp != tdvp)
1479 			vput(tvp);
1480 		else
1481 			vrele(tvp);
1482 	}
1483 	return (error);
1484 }
1485 
1486 static int
1487 union_mkdir(ap)
1488 	struct vop_mkdir_args /* {
1489 		struct vnode *a_dvp;
1490 		struct vnode **a_vpp;
1491 		struct componentname *a_cnp;
1492 		struct vattr *a_vap;
1493 	} */ *ap;
1494 {
1495 	struct union_node *dun = VTOUNION(ap->a_dvp);
1496 	struct componentname *cnp = ap->a_cnp;
1497 	struct thread *td = cnp->cn_thread;
1498 	struct vnode *upperdvp;
1499 	int error = EROFS;
1500 
1501 	if ((upperdvp = union_lock_upper(dun, td)) != NULLVP) {
1502 		struct vnode *vp;
1503 
1504 		error = VOP_MKDIR(upperdvp, &vp, cnp, ap->a_vap);
1505 		union_unlock_upper(upperdvp, td);
1506 
1507 		if (error == 0) {
1508 			VOP_UNLOCK(vp, 0, td);
1509 			UDEBUG(("ALLOCVP-2 FROM %p REFS %d\n", vp, vrefcnt(vp)));
1510 			error = union_allocvp(ap->a_vpp, ap->a_dvp->v_mount,
1511 				ap->a_dvp, NULLVP, cnp, vp, NULLVP, 1);
1512 			UDEBUG(("ALLOCVP-2B FROM %p REFS %d\n", *ap->a_vpp, vrefcnt(vp)));
1513 		}
1514 	}
1515 	return (error);
1516 }
1517 
1518 static int
1519 union_rmdir(ap)
1520 	struct vop_rmdir_args /* {
1521 		struct vnode *a_dvp;
1522 		struct vnode *a_vp;
1523 		struct componentname *a_cnp;
1524 	} */ *ap;
1525 {
1526 	struct union_node *dun = VTOUNION(ap->a_dvp);
1527 	struct union_node *un = VTOUNION(ap->a_vp);
1528 	struct componentname *cnp = ap->a_cnp;
1529 	struct thread *td = cnp->cn_thread;
1530 	struct vnode *upperdvp;
1531 	struct vnode *uppervp;
1532 	int error;
1533 
1534 	if ((upperdvp = union_lock_upper(dun, td)) == NULLVP)
1535 		panic("union rmdir: null upper vnode");
1536 
1537 	if ((uppervp = union_lock_upper(un, td)) != NULLVP) {
1538 		if (union_dowhiteout(un, cnp->cn_cred, td))
1539 			cnp->cn_flags |= DOWHITEOUT;
1540 		if (cnp->cn_flags & DOWHITEOUT)		/* XXX fs corruption */
1541 			error = EOPNOTSUPP;
1542 		else
1543 			error = VOP_RMDIR(upperdvp, uppervp, ap->a_cnp);
1544 		if (!error)
1545 			union_removed_upper(un);
1546 		union_unlock_upper(uppervp, td);
1547 	} else {
1548 		error = union_mkwhiteout(
1549 			    MOUNTTOUNIONMOUNT(ap->a_dvp->v_mount),
1550 			    dun->un_uppervp, ap->a_cnp, un->un_path);
1551 	}
1552 	union_unlock_upper(upperdvp, td);
1553 	return (error);
1554 }
1555 
1556 /*
1557  *	union_symlink:
1558  *
1559  *	dvp is locked on entry and remains locked on return.  a_vpp is garbage
1560  *	(unused).
1561  */
1562 
1563 static int
1564 union_symlink(ap)
1565 	struct vop_symlink_args /* {
1566 		struct vnode *a_dvp;
1567 		struct vnode **a_vpp;
1568 		struct componentname *a_cnp;
1569 		struct vattr *a_vap;
1570 		char *a_target;
1571 	} */ *ap;
1572 {
1573 	struct union_node *dun = VTOUNION(ap->a_dvp);
1574 	struct componentname *cnp = ap->a_cnp;
1575 	struct thread *td = cnp->cn_thread;
1576 	struct vnode *dvp;
1577 	int error = EROFS;
1578 
1579 	if ((dvp = union_lock_upper(dun, td)) != NULLVP) {
1580 		error = VOP_SYMLINK(dvp, ap->a_vpp, cnp, ap->a_vap,
1581 			    ap->a_target);
1582 		union_unlock_upper(dvp, td);
1583 	}
1584 	return (error);
1585 }
1586 
1587 /*
1588  * union_readdir ()works in concert with getdirentries() and
1589  * readdir(3) to provide a list of entries in the unioned
1590  * directories.  getdirentries()  is responsible for walking
1591  * down the union stack.  readdir(3) is responsible for
1592  * eliminating duplicate names from the returned data stream.
1593  */
1594 static int
1595 union_readdir(ap)
1596 	struct vop_readdir_args /* {
1597 		struct vnode *a_vp;
1598 		struct uio *a_uio;
1599 		struct ucred *a_cred;
1600 		int *a_eofflag;
1601 		u_long *a_cookies;
1602 		int a_ncookies;
1603 	} */ *ap;
1604 {
1605 	struct union_node *un = VTOUNION(ap->a_vp);
1606 	struct thread *td = ap->a_uio->uio_td;
1607 	struct vnode *uvp;
1608 	int error = 0;
1609 
1610 	if ((uvp = union_lock_upper(un, td)) != NULLVP) {
1611 		ap->a_vp = uvp;
1612 		error = VCALL(uvp, VOFFSET(vop_readdir), ap);
1613 		union_unlock_upper(uvp, td);
1614 	}
1615 	return(error);
1616 }
1617 
1618 static int
1619 union_readlink(ap)
1620 	struct vop_readlink_args /* {
1621 		struct vnode *a_vp;
1622 		struct uio *a_uio;
1623 		struct ucred *a_cred;
1624 	} */ *ap;
1625 {
1626 	int error;
1627 	struct union_node *un = VTOUNION(ap->a_vp);
1628 	struct uio *uio = ap->a_uio;
1629 	struct thread *td = uio->uio_td;
1630 	struct vnode *vp;
1631 
1632 	vp = union_lock_other(un, td);
1633 	KASSERT(vp != NULL, ("union_readlink: backing vnode missing!"));
1634 
1635 	ap->a_vp = vp;
1636 	error = VCALL(vp, VOFFSET(vop_readlink), ap);
1637 	union_unlock_other(vp, td);
1638 
1639 	return (error);
1640 }
1641 
1642 static int
1643 union_getwritemount(ap)
1644 	struct vop_getwritemount_args /* {
1645 		struct vnode *a_vp;
1646 		struct mount **a_mpp;
1647 	} */ *ap;
1648 {
1649 	struct vnode *vp = ap->a_vp;
1650 	struct vnode *uvp = UPPERVP(vp);
1651 
1652 	if (uvp == NULL) {
1653 		VI_LOCK(vp);
1654 		if (vp->v_iflag & VI_FREE) {
1655 			VI_UNLOCK(vp);
1656 			return (EOPNOTSUPP);
1657 		}
1658 		VI_UNLOCK(vp);
1659 		return (EACCES);
1660 	}
1661 	return(VOP_GETWRITEMOUNT(uvp, ap->a_mpp));
1662 }
1663 
1664 /*
1665  *	union_inactive:
1666  *
1667  *	Called with the vnode locked.  We are expected to unlock the vnode.
1668  */
1669 
1670 static int
1671 union_inactive(ap)
1672 	struct vop_inactive_args /* {
1673 		struct vnode *a_vp;
1674 		struct thread *a_td;
1675 	} */ *ap;
1676 {
1677 	struct vnode *vp = ap->a_vp;
1678 	struct thread *td = ap->a_td;
1679 	struct union_node *un = VTOUNION(vp);
1680 
1681 	/*
1682 	 * Do nothing (and _don't_ bypass).
1683 	 * Wait to vrele lowervp until reclaim,
1684 	 * so that until then our union_node is in the
1685 	 * cache and reusable.
1686 	 *
1687 	 */
1688 
1689 	if (un->un_dircache != NULL)
1690 		union_dircache_free(un);
1691 
1692 #if 0
1693 	if ((un->un_flags & UN_ULOCK) && un->un_uppervp) {
1694 		un->un_flags &= ~UN_ULOCK;
1695 		VOP_UNLOCK(un->un_uppervp, 0, td);
1696 	}
1697 #endif
1698 
1699 	VOP_UNLOCK(vp, 0, td);
1700 
1701 	if ((un->un_flags & UN_CACHED) == 0)
1702 		vgone(vp);
1703 
1704 	return (0);
1705 }
1706 
1707 static int
1708 union_reclaim(ap)
1709 	struct vop_reclaim_args /* {
1710 		struct vnode *a_vp;
1711 	} */ *ap;
1712 {
1713 	union_freevp(ap->a_vp);
1714 
1715 	return (0);
1716 }
1717 
1718 /*
1719  * unionvp do not hold a VM object and there is no need to create one for
1720  * upper or lower vp because it is done in the union_open()
1721  */
1722 static int
1723 union_createvobject(ap)
1724 	struct vop_createvobject_args /* {
1725 		struct vnode *vp;
1726 		struct ucred *cred;
1727 		struct thread *td;
1728 	} */ *ap;
1729 {
1730 	struct vnode *vp = ap->a_vp;
1731 
1732 	vp->v_vflag |= VV_OBJBUF;
1733 	return (0);
1734 }
1735 
1736 /*
1737  * We have nothing to destroy and this operation shouldn't be bypassed.
1738  */
1739 static int
1740 union_destroyvobject(ap)
1741 	struct vop_destroyvobject_args /* {
1742 		struct vnode *vp;
1743 	} */ *ap;
1744 {
1745 	struct vnode *vp = ap->a_vp;
1746 
1747 	vp->v_vflag &= ~VV_OBJBUF;
1748 	return (0);
1749 }
1750 
1751 /*
1752  * Get VM object from the upper or lower vp
1753  */
1754 static int
1755 union_getvobject(ap)
1756 	struct vop_getvobject_args /* {
1757 		struct vnode *vp;
1758 		struct vm_object **objpp;
1759 	} */ *ap;
1760 {
1761 	struct vnode *ovp = OTHERVP(ap->a_vp);
1762 
1763 	if (ovp == NULL)
1764 		return EINVAL;
1765 	return (VOP_GETVOBJECT(ovp, ap->a_objpp));
1766 }
1767 
1768 static int
1769 union_print(ap)
1770 	struct vop_print_args /* {
1771 		struct vnode *a_vp;
1772 	} */ *ap;
1773 {
1774 	struct vnode *vp = ap->a_vp;
1775 
1776 	printf("\tvp=%p, uppervp=%p, lowervp=%p\n",
1777 	       vp, UPPERVP(vp), LOWERVP(vp));
1778 	if (UPPERVP(vp) != NULLVP)
1779 		vprint("union: upper", UPPERVP(vp));
1780 	if (LOWERVP(vp) != NULLVP)
1781 		vprint("union: lower", LOWERVP(vp));
1782 
1783 	return (0);
1784 }
1785 
1786 static int
1787 union_pathconf(ap)
1788 	struct vop_pathconf_args /* {
1789 		struct vnode *a_vp;
1790 		int a_name;
1791 		int *a_retval;
1792 	} */ *ap;
1793 {
1794 	int error;
1795 	struct thread *td = curthread;		/* XXX */
1796 	struct union_node *un = VTOUNION(ap->a_vp);
1797 	struct vnode *vp;
1798 
1799 	vp = union_lock_other(un, td);
1800 	KASSERT(vp != NULL, ("union_pathconf: backing vnode missing!"));
1801 
1802 	ap->a_vp = vp;
1803 	error = VCALL(vp, VOFFSET(vop_pathconf), ap);
1804 	union_unlock_other(vp, td);
1805 
1806 	return (error);
1807 }
1808 
1809 static int
1810 union_advlock(ap)
1811 	struct vop_advlock_args /* {
1812 		struct vnode *a_vp;
1813 		caddr_t  a_id;
1814 		int  a_op;
1815 		struct flock *a_fl;
1816 		int  a_flags;
1817 	} */ *ap;
1818 {
1819 	register struct vnode *ovp = OTHERVP(ap->a_vp);
1820 
1821 	ap->a_vp = ovp;
1822 	return (VCALL(ovp, VOFFSET(vop_advlock), ap));
1823 }
1824 
1825 
1826 /*
1827  * XXX - vop_strategy must be hand coded because it has no
1828  * YYY - and it is not coherent with anything
1829  *
1830  * vnode in its arguments.
1831  * This goes away with a merged VM/buffer cache.
1832  */
1833 static int
1834 union_strategy(ap)
1835 	struct vop_strategy_args /* {
1836 		struct vnode *a_vp;
1837 		struct buf *a_bp;
1838 	} */ *ap;
1839 {
1840 	struct buf *bp = ap->a_bp;
1841 	struct vnode *othervp = OTHERVP(bp->b_vp);
1842 
1843 	KASSERT(ap->a_vp == ap->a_bp->b_vp, ("%s(%p != %p)",
1844 	    __func__, ap->a_vp, ap->a_bp->b_vp));
1845 #ifdef DIAGNOSTIC
1846 	if (othervp == NULLVP)
1847 		panic("union_strategy: nil vp");
1848 	if ((bp->b_iocmd == BIO_WRITE) &&
1849 	    (othervp == LOWERVP(bp->b_vp)))
1850 		panic("union_strategy: writing to lowervp");
1851 #endif
1852 	return (VOP_STRATEGY(othervp, bp));
1853 }
1854 
1855 static int
1856 union_getacl(ap)
1857 	struct vop_getacl_args /* {
1858 		struct vnode *a_vp;
1859 		acl_type_t a_type;
1860 		struct acl *a_aclp;
1861 		struct ucred *a_cred;
1862 		struct thread *a_td;
1863 	} */ *ap;
1864 {
1865 	int error;
1866 	struct union_node *un = VTOUNION(ap->a_vp);
1867 	struct vnode *vp;
1868 
1869 	vp = union_lock_other(un, ap->a_td);
1870 	ap->a_vp = vp;
1871 	error = VCALL(vp, VOFFSET(vop_getacl), ap);
1872 	union_unlock_other(vp, ap->a_td);
1873 
1874 	return (error);
1875 }
1876 
1877 static int
1878 union_setacl(ap)
1879 	struct vop_setacl_args /* {
1880 		struct vnode *a_vp;
1881 		acl_type_t a_type;
1882 		struct acl *a_aclp;
1883 		struct ucred *a_cred;
1884 		struct thread *a_td;
1885 	} */ *ap;
1886 {
1887 	int error;
1888 	struct union_node *un = VTOUNION(ap->a_vp);
1889 	struct vnode *vp;
1890 
1891 	vp = union_lock_other(un, ap->a_td);
1892 	ap->a_vp = vp;
1893 	error = VCALL(vp, VOFFSET(vop_setacl), ap);
1894 	union_unlock_other(vp, ap->a_td);
1895 
1896 	return (error);
1897 }
1898 
1899 static int
1900 union_aclcheck(ap)
1901 	struct vop_aclcheck_args /* {
1902 		struct vnode *a_vp;
1903 		acl_type_t a_type;
1904 		struct acl *a_aclp;
1905 		struct ucred *a_cred;
1906 		struct thread *a_td;
1907 	} */ *ap;
1908 {
1909 	struct vnode *ovp = OTHERVP(ap->a_vp);
1910 
1911 	ap->a_vp = ovp;
1912 	return (VCALL(ovp, VOFFSET(vop_aclcheck), ap));
1913 }
1914 
1915 static int
1916 union_closeextattr(ap)
1917 	struct vop_closeextattr_args /* {
1918 		struct vnode *a_vp;
1919 		int a_commit;
1920 		struct ucred *a_cred;
1921 		struct thread *a_td;
1922 	} */ *ap;
1923 {
1924 	int error;
1925 	struct union_node *un = VTOUNION(ap->a_vp);
1926 	struct vnode *vp;
1927 
1928 	vp = union_lock_other(un, ap->a_td);
1929 	ap->a_vp = vp;
1930 	error = VCALL(vp, VOFFSET(vop_closeextattr), ap);
1931 	union_unlock_other(vp, ap->a_td);
1932 
1933 	return (error);
1934 }
1935 
1936 static int
1937 union_getextattr(ap)
1938 	struct vop_getextattr_args /* {
1939 		struct vnode *a_vp;
1940 		int a_attrnamespace;
1941 		const char *a_name;
1942 		struct uio *a_uio;
1943 		size_t *a_size;
1944 		struct ucred *a_cred;
1945 		struct thread *a_td;
1946 	} */ *ap;
1947 {
1948 	int error;
1949 	struct union_node *un = VTOUNION(ap->a_vp);
1950 	struct vnode *vp;
1951 
1952 	vp = union_lock_other(un, ap->a_td);
1953 	ap->a_vp = vp;
1954 	error = VCALL(vp, VOFFSET(vop_getextattr), ap);
1955 	union_unlock_other(vp, ap->a_td);
1956 
1957 	return (error);
1958 }
1959 
1960 static int
1961 union_listextattr(ap)
1962 	struct vop_listextattr_args /* {
1963 		struct vnode *a_vp;
1964 		int a_attrnamespace;
1965 		struct uio *a_uio;
1966 		size_t *a_size;
1967 		struct ucred *a_cred;
1968 		struct thread *a_td;
1969 	} */ *ap;
1970 {
1971 	int error;
1972 	struct union_node *un = VTOUNION(ap->a_vp);
1973 	struct vnode *vp;
1974 
1975 	vp = union_lock_other(un, ap->a_td);
1976 	ap->a_vp = vp;
1977 	error = VCALL(vp, VOFFSET(vop_listextattr), ap);
1978 	union_unlock_other(vp, ap->a_td);
1979 
1980 	return (error);
1981 }
1982 
1983 static int
1984 union_openextattr(ap)
1985 	struct vop_openextattr_args /* {
1986 		struct vnode *a_vp;
1987 		struct ucred *a_cred;
1988 		struct thread *a_td;
1989 	} */ *ap;
1990 {
1991 	int error;
1992 	struct union_node *un = VTOUNION(ap->a_vp);
1993 	struct vnode *vp;
1994 
1995 	vp = union_lock_other(un, ap->a_td);
1996 	ap->a_vp = vp;
1997 	error = VCALL(vp, VOFFSET(vop_openextattr), ap);
1998 	union_unlock_other(vp, ap->a_td);
1999 
2000 	return (error);
2001 }
2002 
2003 static int
2004 union_deleteextattr(ap)
2005 	struct vop_deleteextattr_args /* {
2006 		struct vnode *a_vp;
2007 		int a_attrnamespace;
2008 		const char *a_name;
2009 		struct ucred *a_cred;
2010 		struct thread *a_td;
2011 	} */ *ap;
2012 {
2013 	int error;
2014 	struct union_node *un = VTOUNION(ap->a_vp);
2015 	struct vnode *vp;
2016 
2017 	vp = union_lock_other(un, ap->a_td);
2018 	ap->a_vp = vp;
2019 	error = VCALL(vp, VOFFSET(vop_deleteextattr), ap);
2020 	union_unlock_other(vp, ap->a_td);
2021 
2022 	return (error);
2023 }
2024 
2025 static int
2026 union_setextattr(ap)
2027 	struct vop_setextattr_args /* {
2028 		struct vnode *a_vp;
2029 		int a_attrnamespace;
2030 		const char *a_name;
2031 		struct uio *a_uio;
2032 		struct ucred *a_cred;
2033 		struct thread *a_td;
2034 	} */ *ap;
2035 {
2036 	int error;
2037 	struct union_node *un = VTOUNION(ap->a_vp);
2038 	struct vnode *vp;
2039 
2040 	vp = union_lock_other(un, ap->a_td);
2041 	ap->a_vp = vp;
2042 	error = VCALL(vp, VOFFSET(vop_setextattr), ap);
2043 	union_unlock_other(vp, ap->a_td);
2044 
2045 	return (error);
2046 }
2047 
2048 static int
2049 union_setlabel(ap)
2050 	struct vop_setlabel_args /* {
2051 		struct vnode *a_vp;
2052 		struct label *a_label;
2053 		struct ucred *a_cred;
2054 		struct thread *a_td;
2055 	} */ *ap;
2056 {
2057 	int error;
2058 	struct union_node *un = VTOUNION(ap->a_vp);
2059 	struct vnode *vp;
2060 
2061 	vp = union_lock_other(un, ap->a_td);
2062 	ap->a_vp = vp;
2063 	error = VCALL(vp, VOFFSET(vop_setlabel), ap);
2064 	union_unlock_other(vp, ap->a_td);
2065 
2066 	return (error);
2067 }
2068 
2069 /*
2070  * Global vfs data structures
2071  */
2072 vop_t **union_vnodeop_p;
2073 static struct vnodeopv_entry_desc union_vnodeop_entries[] = {
2074 	{ &vop_default_desc,		(vop_t *) vop_defaultop },
2075 	{ &vop_access_desc,		(vop_t *) union_access },
2076 	{ &vop_aclcheck_desc,		(vop_t *) union_aclcheck },
2077 	{ &vop_advlock_desc,		(vop_t *) union_advlock },
2078 	{ &vop_bmap_desc,		(vop_t *) vop_eopnotsupp },
2079 	{ &vop_close_desc,		(vop_t *) union_close },
2080 	{ &vop_closeextattr_desc,	(vop_t *) union_closeextattr },
2081 	{ &vop_create_desc,		(vop_t *) union_create },
2082 	{ &vop_createvobject_desc,	(vop_t *) union_createvobject },
2083 	{ &vop_deleteextattr_desc,	(vop_t *) union_deleteextattr },
2084 	{ &vop_destroyvobject_desc,	(vop_t *) union_destroyvobject },
2085 	{ &vop_fsync_desc,		(vop_t *) union_fsync },
2086 	{ &vop_getattr_desc,		(vop_t *) union_getattr },
2087 	{ &vop_getacl_desc,		(vop_t *) union_getacl },
2088 	{ &vop_getextattr_desc,		(vop_t *) union_getextattr },
2089 	{ &vop_getvobject_desc,		(vop_t *) union_getvobject },
2090 	{ &vop_inactive_desc,		(vop_t *) union_inactive },
2091 	{ &vop_ioctl_desc,		(vop_t *) union_ioctl },
2092 	{ &vop_lease_desc,		(vop_t *) union_lease },
2093 	{ &vop_link_desc,		(vop_t *) union_link },
2094 	{ &vop_listextattr_desc,	(vop_t *) union_listextattr },
2095 	{ &vop_lookup_desc,		(vop_t *) union_lookup },
2096 	{ &vop_mkdir_desc,		(vop_t *) union_mkdir },
2097 	{ &vop_mknod_desc,		(vop_t *) union_mknod },
2098 	{ &vop_open_desc,		(vop_t *) union_open },
2099 	{ &vop_openextattr_desc,	(vop_t *) union_openextattr },
2100 	{ &vop_pathconf_desc,		(vop_t *) union_pathconf },
2101 	{ &vop_poll_desc,		(vop_t *) union_poll },
2102 	{ &vop_print_desc,		(vop_t *) union_print },
2103 	{ &vop_read_desc,		(vop_t *) union_read },
2104 	{ &vop_readdir_desc,		(vop_t *) union_readdir },
2105 	{ &vop_readlink_desc,		(vop_t *) union_readlink },
2106 	{ &vop_getwritemount_desc,	(vop_t *) union_getwritemount },
2107 	{ &vop_reclaim_desc,		(vop_t *) union_reclaim },
2108 	{ &vop_remove_desc,		(vop_t *) union_remove },
2109 	{ &vop_rename_desc,		(vop_t *) union_rename },
2110 	{ &vop_revoke_desc,		(vop_t *) union_revoke },
2111 	{ &vop_rmdir_desc,		(vop_t *) union_rmdir },
2112 	{ &vop_setacl_desc,		(vop_t *) union_setacl },
2113 	{ &vop_setattr_desc,		(vop_t *) union_setattr },
2114 	{ &vop_setextattr_desc,		(vop_t *) union_setextattr },
2115 	{ &vop_setlabel_desc,		(vop_t *) union_setlabel },
2116 	{ &vop_strategy_desc,		(vop_t *) union_strategy },
2117 	{ &vop_symlink_desc,		(vop_t *) union_symlink },
2118 	{ &vop_whiteout_desc,		(vop_t *) union_whiteout },
2119 	{ &vop_write_desc,		(vop_t *) union_write },
2120 	{ NULL, NULL }
2121 };
2122 static struct vnodeopv_desc union_vnodeop_opv_desc =
2123 	{ &union_vnodeop_p, union_vnodeop_entries };
2124 
2125 VNODEOP_SET(union_vnodeop_opv_desc);
2126