xref: /freebsd/sys/kern/vfs_default.c (revision d8b878873e7aa8df1972cc6a642804b17eb61087)
1 /*-
2  * Copyright (c) 1989, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * This code is derived from software contributed
6  * to Berkeley by John Heidemann of the UCLA Ficus project.
7  *
8  * Source: * @(#)i405_init.c 2.10 92/04/27 UCLA Ficus project
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 4. Neither the name of the University nor the names of its contributors
19  *    may be used to endorse or promote products derived from this software
20  *    without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  */
34 
35 #include <sys/cdefs.h>
36 __FBSDID("$FreeBSD$");
37 
38 #include <sys/param.h>
39 #include <sys/systm.h>
40 #include <sys/bio.h>
41 #include <sys/buf.h>
42 #include <sys/conf.h>
43 #include <sys/event.h>
44 #include <sys/kernel.h>
45 #include <sys/limits.h>
46 #include <sys/lock.h>
47 #include <sys/lockf.h>
48 #include <sys/malloc.h>
49 #include <sys/mount.h>
50 #include <sys/mutex.h>
51 #include <sys/namei.h>
52 #include <sys/fcntl.h>
53 #include <sys/unistd.h>
54 #include <sys/vnode.h>
55 #include <sys/dirent.h>
56 #include <sys/poll.h>
57 
58 #include <security/mac/mac_framework.h>
59 
60 #include <vm/vm.h>
61 #include <vm/vm_object.h>
62 #include <vm/vm_extern.h>
63 #include <vm/pmap.h>
64 #include <vm/vm_map.h>
65 #include <vm/vm_page.h>
66 #include <vm/vm_pager.h>
67 #include <vm/vnode_pager.h>
68 
69 static int	vop_nolookup(struct vop_lookup_args *);
70 static int	vop_norename(struct vop_rename_args *);
71 static int	vop_nostrategy(struct vop_strategy_args *);
72 static int	get_next_dirent(struct vnode *vp, struct dirent **dpp,
73 				char *dirbuf, int dirbuflen, off_t *off,
74 				char **cpos, int *len, int *eofflag,
75 				struct thread *td);
76 static int	dirent_exists(struct vnode *vp, const char *dirname,
77 			      struct thread *td);
78 
79 #define DIRENT_MINSIZE (sizeof(struct dirent) - (MAXNAMLEN+1) + 4)
80 
81 /*
82  * This vnode table stores what we want to do if the filesystem doesn't
83  * implement a particular VOP.
84  *
85  * If there is no specific entry here, we will return EOPNOTSUPP.
86  *
87  * Note that every filesystem has to implement either vop_access
88  * or vop_accessx; failing to do so will result in immediate crash
89  * due to stack overflow, as vop_stdaccess() calls vop_stdaccessx(),
90  * which calls vop_stdaccess() etc.
91  */
92 
93 struct vop_vector default_vnodeops = {
94 	.vop_default =		NULL,
95 	.vop_bypass =		VOP_EOPNOTSUPP,
96 
97 	.vop_access =		vop_stdaccess,
98 	.vop_accessx =		vop_stdaccessx,
99 	.vop_advlock =		vop_stdadvlock,
100 	.vop_advlockasync =	vop_stdadvlockasync,
101 	.vop_bmap =		vop_stdbmap,
102 	.vop_close =		VOP_NULL,
103 	.vop_fsync =		VOP_NULL,
104 	.vop_getpages =		vop_stdgetpages,
105 	.vop_getwritemount = 	vop_stdgetwritemount,
106 	.vop_inactive =		VOP_NULL,
107 	.vop_ioctl =		VOP_ENOTTY,
108 	.vop_kqfilter =		vop_stdkqfilter,
109 	.vop_islocked =		vop_stdislocked,
110 	.vop_lock1 =		vop_stdlock,
111 	.vop_lookup =		vop_nolookup,
112 	.vop_open =		VOP_NULL,
113 	.vop_pathconf =		VOP_EINVAL,
114 	.vop_poll =		vop_nopoll,
115 	.vop_putpages =		vop_stdputpages,
116 	.vop_readlink =		VOP_EINVAL,
117 	.vop_rename =		vop_norename,
118 	.vop_revoke =		VOP_PANIC,
119 	.vop_strategy =		vop_nostrategy,
120 	.vop_unlock =		vop_stdunlock,
121 	.vop_vptocnp =		vop_stdvptocnp,
122 	.vop_vptofh =		vop_stdvptofh,
123 };
124 
125 /*
126  * Series of placeholder functions for various error returns for
127  * VOPs.
128  */
129 
130 int
131 vop_eopnotsupp(struct vop_generic_args *ap)
132 {
133 	/*
134 	printf("vop_notsupp[%s]\n", ap->a_desc->vdesc_name);
135 	*/
136 
137 	return (EOPNOTSUPP);
138 }
139 
140 int
141 vop_ebadf(struct vop_generic_args *ap)
142 {
143 
144 	return (EBADF);
145 }
146 
147 int
148 vop_enotty(struct vop_generic_args *ap)
149 {
150 
151 	return (ENOTTY);
152 }
153 
154 int
155 vop_einval(struct vop_generic_args *ap)
156 {
157 
158 	return (EINVAL);
159 }
160 
161 int
162 vop_enoent(struct vop_generic_args *ap)
163 {
164 
165 	return (ENOENT);
166 }
167 
168 int
169 vop_null(struct vop_generic_args *ap)
170 {
171 
172 	return (0);
173 }
174 
175 /*
176  * Helper function to panic on some bad VOPs in some filesystems.
177  */
178 int
179 vop_panic(struct vop_generic_args *ap)
180 {
181 
182 	panic("filesystem goof: vop_panic[%s]", ap->a_desc->vdesc_name);
183 }
184 
185 /*
186  * vop_std<something> and vop_no<something> are default functions for use by
187  * filesystems that need the "default reasonable" implementation for a
188  * particular operation.
189  *
190  * The documentation for the operations they implement exists (if it exists)
191  * in the VOP_<SOMETHING>(9) manpage (all uppercase).
192  */
193 
194 /*
195  * Default vop for filesystems that do not support name lookup
196  */
197 static int
198 vop_nolookup(ap)
199 	struct vop_lookup_args /* {
200 		struct vnode *a_dvp;
201 		struct vnode **a_vpp;
202 		struct componentname *a_cnp;
203 	} */ *ap;
204 {
205 
206 	*ap->a_vpp = NULL;
207 	return (ENOTDIR);
208 }
209 
210 /*
211  * vop_norename:
212  *
213  * Handle unlock and reference counting for arguments of vop_rename
214  * for filesystems that do not implement rename operation.
215  */
216 static int
217 vop_norename(struct vop_rename_args *ap)
218 {
219 
220 	vop_rename_fail(ap);
221 	return (EOPNOTSUPP);
222 }
223 
224 /*
225  *	vop_nostrategy:
226  *
227  *	Strategy routine for VFS devices that have none.
228  *
229  *	BIO_ERROR and B_INVAL must be cleared prior to calling any strategy
230  *	routine.  Typically this is done for a BIO_READ strategy call.
231  *	Typically B_INVAL is assumed to already be clear prior to a write
232  *	and should not be cleared manually unless you just made the buffer
233  *	invalid.  BIO_ERROR should be cleared either way.
234  */
235 
236 static int
237 vop_nostrategy (struct vop_strategy_args *ap)
238 {
239 	printf("No strategy for buffer at %p\n", ap->a_bp);
240 	vprint("vnode", ap->a_vp);
241 	ap->a_bp->b_ioflags |= BIO_ERROR;
242 	ap->a_bp->b_error = EOPNOTSUPP;
243 	bufdone(ap->a_bp);
244 	return (EOPNOTSUPP);
245 }
246 
247 static int
248 get_next_dirent(struct vnode *vp, struct dirent **dpp, char *dirbuf,
249 		int dirbuflen, off_t *off, char **cpos, int *len,
250 		int *eofflag, struct thread *td)
251 {
252 	int error, reclen;
253 	struct uio uio;
254 	struct iovec iov;
255 	struct dirent *dp;
256 
257 	KASSERT(VOP_ISLOCKED(vp), ("vp %p is not locked", vp));
258 	KASSERT(vp->v_type == VDIR, ("vp %p is not a directory", vp));
259 
260 	if (*len == 0) {
261 		iov.iov_base = dirbuf;
262 		iov.iov_len = dirbuflen;
263 
264 		uio.uio_iov = &iov;
265 		uio.uio_iovcnt = 1;
266 		uio.uio_offset = *off;
267 		uio.uio_resid = dirbuflen;
268 		uio.uio_segflg = UIO_SYSSPACE;
269 		uio.uio_rw = UIO_READ;
270 		uio.uio_td = td;
271 
272 		*eofflag = 0;
273 
274 #ifdef MAC
275 		error = mac_vnode_check_readdir(td->td_ucred, vp);
276 		if (error == 0)
277 #endif
278 			error = VOP_READDIR(vp, &uio, td->td_ucred, eofflag,
279 		    		NULL, NULL);
280 		if (error)
281 			return (error);
282 
283 		*off = uio.uio_offset;
284 
285 		*cpos = dirbuf;
286 		*len = (dirbuflen - uio.uio_resid);
287 	}
288 
289 	dp = (struct dirent *)(*cpos);
290 	reclen = dp->d_reclen;
291 	*dpp = dp;
292 
293 	/* check for malformed directory.. */
294 	if (reclen < DIRENT_MINSIZE)
295 		return (EINVAL);
296 
297 	*cpos += reclen;
298 	*len -= reclen;
299 
300 	return (0);
301 }
302 
303 /*
304  * Check if a named file exists in a given directory vnode.
305  */
306 static int
307 dirent_exists(struct vnode *vp, const char *dirname, struct thread *td)
308 {
309 	char *dirbuf, *cpos;
310 	int error, eofflag, dirbuflen, len, found;
311 	off_t off;
312 	struct dirent *dp;
313 	struct vattr va;
314 
315 	KASSERT(VOP_ISLOCKED(vp), ("vp %p is not locked", vp));
316 	KASSERT(vp->v_type == VDIR, ("vp %p is not a directory", vp));
317 
318 	found = 0;
319 
320 	error = VOP_GETATTR(vp, &va, td->td_ucred);
321 	if (error)
322 		return (found);
323 
324 	dirbuflen = DEV_BSIZE;
325 	if (dirbuflen < va.va_blocksize)
326 		dirbuflen = va.va_blocksize;
327 	dirbuf = (char *)malloc(dirbuflen, M_TEMP, M_WAITOK);
328 
329 	off = 0;
330 	len = 0;
331 	do {
332 		error = get_next_dirent(vp, &dp, dirbuf, dirbuflen, &off,
333 					&cpos, &len, &eofflag, td);
334 		if (error)
335 			goto out;
336 
337 		if ((dp->d_type != DT_WHT) &&
338 		    !strcmp(dp->d_name, dirname)) {
339 			found = 1;
340 			goto out;
341 		}
342 	} while (len > 0 || !eofflag);
343 
344 out:
345 	free(dirbuf, M_TEMP);
346 	return (found);
347 }
348 
349 int
350 vop_stdaccess(struct vop_access_args *ap)
351 {
352 
353 	KASSERT((ap->a_accmode & ~(VEXEC | VWRITE | VREAD | VADMIN |
354 	    VAPPEND)) == 0, ("invalid bit in accmode"));
355 
356 	return (VOP_ACCESSX(ap->a_vp, ap->a_accmode, ap->a_cred, ap->a_td));
357 }
358 
359 int
360 vop_stdaccessx(struct vop_accessx_args *ap)
361 {
362 	int error;
363 	accmode_t accmode = ap->a_accmode;
364 
365 	error = vfs_unixify_accmode(&accmode);
366 	if (error != 0)
367 		return (error);
368 
369 	if (accmode == 0)
370 		return (0);
371 
372 	return (VOP_ACCESS(ap->a_vp, accmode, ap->a_cred, ap->a_td));
373 }
374 
375 /*
376  * Advisory record locking support
377  */
378 int
379 vop_stdadvlock(struct vop_advlock_args *ap)
380 {
381 	struct vnode *vp;
382 	struct ucred *cred;
383 	struct vattr vattr;
384 	int error;
385 
386 	vp = ap->a_vp;
387 	cred = curthread->td_ucred;
388 	vn_lock(vp, LK_SHARED | LK_RETRY);
389 	error = VOP_GETATTR(vp, &vattr, cred);
390 	VOP_UNLOCK(vp, 0);
391 	if (error)
392 		return (error);
393 
394 	return (lf_advlock(ap, &(vp->v_lockf), vattr.va_size));
395 }
396 
397 int
398 vop_stdadvlockasync(struct vop_advlockasync_args *ap)
399 {
400 	struct vnode *vp;
401 	struct ucred *cred;
402 	struct vattr vattr;
403 	int error;
404 
405 	vp = ap->a_vp;
406 	cred = curthread->td_ucred;
407 	vn_lock(vp, LK_SHARED | LK_RETRY);
408 	error = VOP_GETATTR(vp, &vattr, cred);
409 	VOP_UNLOCK(vp, 0);
410 	if (error)
411 		return (error);
412 
413 	return (lf_advlockasync(ap, &(vp->v_lockf), vattr.va_size));
414 }
415 
416 /*
417  * vop_stdpathconf:
418  *
419  * Standard implementation of POSIX pathconf, to get information about limits
420  * for a filesystem.
421  * Override per filesystem for the case where the filesystem has smaller
422  * limits.
423  */
424 int
425 vop_stdpathconf(ap)
426 	struct vop_pathconf_args /* {
427 	struct vnode *a_vp;
428 	int a_name;
429 	int *a_retval;
430 	} */ *ap;
431 {
432 
433 	switch (ap->a_name) {
434 		case _PC_NAME_MAX:
435 			*ap->a_retval = NAME_MAX;
436 			return (0);
437 		case _PC_PATH_MAX:
438 			*ap->a_retval = PATH_MAX;
439 			return (0);
440 		case _PC_LINK_MAX:
441 			*ap->a_retval = LINK_MAX;
442 			return (0);
443 		case _PC_MAX_CANON:
444 			*ap->a_retval = MAX_CANON;
445 			return (0);
446 		case _PC_MAX_INPUT:
447 			*ap->a_retval = MAX_INPUT;
448 			return (0);
449 		case _PC_PIPE_BUF:
450 			*ap->a_retval = PIPE_BUF;
451 			return (0);
452 		case _PC_CHOWN_RESTRICTED:
453 			*ap->a_retval = 1;
454 			return (0);
455 		case _PC_VDISABLE:
456 			*ap->a_retval = _POSIX_VDISABLE;
457 			return (0);
458 		default:
459 			return (EINVAL);
460 	}
461 	/* NOTREACHED */
462 }
463 
464 /*
465  * Standard lock, unlock and islocked functions.
466  */
467 int
468 vop_stdlock(ap)
469 	struct vop_lock1_args /* {
470 		struct vnode *a_vp;
471 		int a_flags;
472 		char *file;
473 		int line;
474 	} */ *ap;
475 {
476 	struct vnode *vp = ap->a_vp;
477 
478 	return (_lockmgr_args(vp->v_vnlock, ap->a_flags, VI_MTX(vp),
479 	    LK_WMESG_DEFAULT, LK_PRIO_DEFAULT, LK_TIMO_DEFAULT, ap->a_file,
480 	    ap->a_line));
481 }
482 
483 /* See above. */
484 int
485 vop_stdunlock(ap)
486 	struct vop_unlock_args /* {
487 		struct vnode *a_vp;
488 		int a_flags;
489 	} */ *ap;
490 {
491 	struct vnode *vp = ap->a_vp;
492 
493 	return (lockmgr(vp->v_vnlock, ap->a_flags | LK_RELEASE, VI_MTX(vp)));
494 }
495 
496 /* See above. */
497 int
498 vop_stdislocked(ap)
499 	struct vop_islocked_args /* {
500 		struct vnode *a_vp;
501 	} */ *ap;
502 {
503 
504 	return (lockstatus(ap->a_vp->v_vnlock));
505 }
506 
507 /*
508  * Return true for select/poll.
509  */
510 int
511 vop_nopoll(ap)
512 	struct vop_poll_args /* {
513 		struct vnode *a_vp;
514 		int  a_events;
515 		struct ucred *a_cred;
516 		struct thread *a_td;
517 	} */ *ap;
518 {
519 
520 	return (poll_no_poll(ap->a_events));
521 }
522 
523 /*
524  * Implement poll for local filesystems that support it.
525  */
526 int
527 vop_stdpoll(ap)
528 	struct vop_poll_args /* {
529 		struct vnode *a_vp;
530 		int  a_events;
531 		struct ucred *a_cred;
532 		struct thread *a_td;
533 	} */ *ap;
534 {
535 	if (ap->a_events & ~POLLSTANDARD)
536 		return (vn_pollrecord(ap->a_vp, ap->a_td, ap->a_events));
537 	return (ap->a_events & (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM));
538 }
539 
540 /*
541  * Return our mount point, as we will take charge of the writes.
542  */
543 int
544 vop_stdgetwritemount(ap)
545 	struct vop_getwritemount_args /* {
546 		struct vnode *a_vp;
547 		struct mount **a_mpp;
548 	} */ *ap;
549 {
550 	struct mount *mp;
551 
552 	/*
553 	 * XXX Since this is called unlocked we may be recycled while
554 	 * attempting to ref the mount.  If this is the case or mountpoint
555 	 * will be set to NULL.  We only have to prevent this call from
556 	 * returning with a ref to an incorrect mountpoint.  It is not
557 	 * harmful to return with a ref to our previous mountpoint.
558 	 */
559 	mp = ap->a_vp->v_mount;
560 	if (mp != NULL) {
561 		vfs_ref(mp);
562 		if (mp != ap->a_vp->v_mount) {
563 			vfs_rel(mp);
564 			mp = NULL;
565 		}
566 	}
567 	*(ap->a_mpp) = mp;
568 	return (0);
569 }
570 
571 /* XXX Needs good comment and VOP_BMAP(9) manpage */
572 int
573 vop_stdbmap(ap)
574 	struct vop_bmap_args /* {
575 		struct vnode *a_vp;
576 		daddr_t  a_bn;
577 		struct bufobj **a_bop;
578 		daddr_t *a_bnp;
579 		int *a_runp;
580 		int *a_runb;
581 	} */ *ap;
582 {
583 
584 	if (ap->a_bop != NULL)
585 		*ap->a_bop = &ap->a_vp->v_bufobj;
586 	if (ap->a_bnp != NULL)
587 		*ap->a_bnp = ap->a_bn * btodb(ap->a_vp->v_mount->mnt_stat.f_iosize);
588 	if (ap->a_runp != NULL)
589 		*ap->a_runp = 0;
590 	if (ap->a_runb != NULL)
591 		*ap->a_runb = 0;
592 	return (0);
593 }
594 
595 int
596 vop_stdfsync(ap)
597 	struct vop_fsync_args /* {
598 		struct vnode *a_vp;
599 		struct ucred *a_cred;
600 		int a_waitfor;
601 		struct thread *a_td;
602 	} */ *ap;
603 {
604 	struct vnode *vp = ap->a_vp;
605 	struct buf *bp;
606 	struct bufobj *bo;
607 	struct buf *nbp;
608 	int error = 0;
609 	int maxretry = 1000;     /* large, arbitrarily chosen */
610 
611 	bo = &vp->v_bufobj;
612 	BO_LOCK(bo);
613 loop1:
614 	/*
615 	 * MARK/SCAN initialization to avoid infinite loops.
616 	 */
617         TAILQ_FOREACH(bp, &bo->bo_dirty.bv_hd, b_bobufs) {
618                 bp->b_vflags &= ~BV_SCANNED;
619 		bp->b_error = 0;
620 	}
621 
622 	/*
623 	 * Flush all dirty buffers associated with a vnode.
624 	 */
625 loop2:
626 	TAILQ_FOREACH_SAFE(bp, &bo->bo_dirty.bv_hd, b_bobufs, nbp) {
627 		if ((bp->b_vflags & BV_SCANNED) != 0)
628 			continue;
629 		bp->b_vflags |= BV_SCANNED;
630 		if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL))
631 			continue;
632 		BO_UNLOCK(bo);
633 		KASSERT(bp->b_bufobj == bo,
634 		    ("bp %p wrong b_bufobj %p should be %p",
635 		    bp, bp->b_bufobj, bo));
636 		if ((bp->b_flags & B_DELWRI) == 0)
637 			panic("fsync: not dirty");
638 		if ((vp->v_object != NULL) && (bp->b_flags & B_CLUSTEROK)) {
639 			vfs_bio_awrite(bp);
640 		} else {
641 			bremfree(bp);
642 			bawrite(bp);
643 		}
644 		BO_LOCK(bo);
645 		goto loop2;
646 	}
647 
648 	/*
649 	 * If synchronous the caller expects us to completely resolve all
650 	 * dirty buffers in the system.  Wait for in-progress I/O to
651 	 * complete (which could include background bitmap writes), then
652 	 * retry if dirty blocks still exist.
653 	 */
654 	if (ap->a_waitfor == MNT_WAIT) {
655 		bufobj_wwait(bo, 0, 0);
656 		if (bo->bo_dirty.bv_cnt > 0) {
657 			/*
658 			 * If we are unable to write any of these buffers
659 			 * then we fail now rather than trying endlessly
660 			 * to write them out.
661 			 */
662 			TAILQ_FOREACH(bp, &bo->bo_dirty.bv_hd, b_bobufs)
663 				if ((error = bp->b_error) == 0)
664 					continue;
665 			if (error == 0 && --maxretry >= 0)
666 				goto loop1;
667 			error = EAGAIN;
668 		}
669 	}
670 	BO_UNLOCK(bo);
671 	if (error == EAGAIN)
672 		vprint("fsync: giving up on dirty", vp);
673 
674 	return (error);
675 }
676 
677 /* XXX Needs good comment and more info in the manpage (VOP_GETPAGES(9)). */
678 int
679 vop_stdgetpages(ap)
680 	struct vop_getpages_args /* {
681 		struct vnode *a_vp;
682 		vm_page_t *a_m;
683 		int a_count;
684 		int a_reqpage;
685 		vm_ooffset_t a_offset;
686 	} */ *ap;
687 {
688 
689 	return vnode_pager_generic_getpages(ap->a_vp, ap->a_m,
690 	    ap->a_count, ap->a_reqpage);
691 }
692 
693 int
694 vop_stdkqfilter(struct vop_kqfilter_args *ap)
695 {
696 	return vfs_kqfilter(ap);
697 }
698 
699 /* XXX Needs good comment and more info in the manpage (VOP_PUTPAGES(9)). */
700 int
701 vop_stdputpages(ap)
702 	struct vop_putpages_args /* {
703 		struct vnode *a_vp;
704 		vm_page_t *a_m;
705 		int a_count;
706 		int a_sync;
707 		int *a_rtvals;
708 		vm_ooffset_t a_offset;
709 	} */ *ap;
710 {
711 
712 	return vnode_pager_generic_putpages(ap->a_vp, ap->a_m, ap->a_count,
713 	     ap->a_sync, ap->a_rtvals);
714 }
715 
716 int
717 vop_stdvptofh(struct vop_vptofh_args *ap)
718 {
719 	return (EOPNOTSUPP);
720 }
721 
722 int
723 vop_stdvptocnp(struct vop_vptocnp_args *ap)
724 {
725 	struct vnode *vp = ap->a_vp;
726 	struct vnode **dvp = ap->a_vpp;
727 	struct ucred *cred = ap->a_cred;
728 	char *buf = ap->a_buf;
729 	int *buflen = ap->a_buflen;
730 	char *dirbuf, *cpos;
731 	int i, error, eofflag, dirbuflen, flags, locked, len, covered;
732 	off_t off;
733 	ino_t fileno;
734 	struct vattr va;
735 	struct nameidata nd;
736 	struct thread *td;
737 	struct dirent *dp;
738 	struct vnode *mvp;
739 
740 	i = *buflen;
741 	error = 0;
742 	covered = 0;
743 	td = curthread;
744 
745 	if (vp->v_type != VDIR)
746 		return (ENOENT);
747 
748 	error = VOP_GETATTR(vp, &va, cred);
749 	if (error)
750 		return (error);
751 
752 	VREF(vp);
753 	locked = VOP_ISLOCKED(vp);
754 	VOP_UNLOCK(vp, 0);
755 	NDINIT_ATVP(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE,
756 	    "..", vp, td);
757 	flags = FREAD;
758 	error = vn_open_cred(&nd, &flags, 0, VN_OPEN_NOAUDIT, cred, NULL);
759 	if (error) {
760 		vn_lock(vp, locked | LK_RETRY);
761 		return (error);
762 	}
763 	NDFREE(&nd, NDF_ONLY_PNBUF);
764 
765 	mvp = *dvp = nd.ni_vp;
766 
767 	if (vp->v_mount != (*dvp)->v_mount &&
768 	    ((*dvp)->v_vflag & VV_ROOT) &&
769 	    ((*dvp)->v_mount->mnt_flag & MNT_UNION)) {
770 		*dvp = (*dvp)->v_mount->mnt_vnodecovered;
771 		VREF(mvp);
772 		VOP_UNLOCK(mvp, 0);
773 		vn_close(mvp, FREAD, cred, td);
774 		VREF(*dvp);
775 		vn_lock(*dvp, LK_EXCLUSIVE | LK_RETRY);
776 		covered = 1;
777 	}
778 
779 	fileno = va.va_fileid;
780 
781 	dirbuflen = DEV_BSIZE;
782 	if (dirbuflen < va.va_blocksize)
783 		dirbuflen = va.va_blocksize;
784 	dirbuf = (char *)malloc(dirbuflen, M_TEMP, M_WAITOK);
785 
786 	if ((*dvp)->v_type != VDIR) {
787 		error = ENOENT;
788 		goto out;
789 	}
790 
791 	off = 0;
792 	len = 0;
793 	do {
794 		/* call VOP_READDIR of parent */
795 		error = get_next_dirent(*dvp, &dp, dirbuf, dirbuflen, &off,
796 					&cpos, &len, &eofflag, td);
797 		if (error)
798 			goto out;
799 
800 		if ((dp->d_type != DT_WHT) &&
801 		    (dp->d_fileno == fileno)) {
802 			if (covered) {
803 				VOP_UNLOCK(*dvp, 0);
804 				vn_lock(mvp, LK_EXCLUSIVE | LK_RETRY);
805 				if (dirent_exists(mvp, dp->d_name, td)) {
806 					error = ENOENT;
807 					VOP_UNLOCK(mvp, 0);
808 					vn_lock(*dvp, LK_EXCLUSIVE | LK_RETRY);
809 					goto out;
810 				}
811 				VOP_UNLOCK(mvp, 0);
812 				vn_lock(*dvp, LK_EXCLUSIVE | LK_RETRY);
813 			}
814 			i -= dp->d_namlen;
815 
816 			if (i < 0) {
817 				error = ENOMEM;
818 				goto out;
819 			}
820 			bcopy(dp->d_name, buf + i, dp->d_namlen);
821 			error = 0;
822 			goto out;
823 		}
824 	} while (len > 0 || !eofflag);
825 	error = ENOENT;
826 
827 out:
828 	free(dirbuf, M_TEMP);
829 	if (!error) {
830 		*buflen = i;
831 		vhold(*dvp);
832 	}
833 	if (covered) {
834 		vput(*dvp);
835 		vrele(mvp);
836 	} else {
837 		VOP_UNLOCK(mvp, 0);
838 		vn_close(mvp, FREAD, cred, td);
839 	}
840 	vn_lock(vp, locked | LK_RETRY);
841 	return (error);
842 }
843 
844 /*
845  * vfs default ops
846  * used to fill the vfs function table to get reasonable default return values.
847  */
848 int
849 vfs_stdroot (mp, flags, vpp)
850 	struct mount *mp;
851 	int flags;
852 	struct vnode **vpp;
853 {
854 
855 	return (EOPNOTSUPP);
856 }
857 
858 int
859 vfs_stdstatfs (mp, sbp)
860 	struct mount *mp;
861 	struct statfs *sbp;
862 {
863 
864 	return (EOPNOTSUPP);
865 }
866 
867 int
868 vfs_stdquotactl (mp, cmds, uid, arg)
869 	struct mount *mp;
870 	int cmds;
871 	uid_t uid;
872 	void *arg;
873 {
874 
875 	return (EOPNOTSUPP);
876 }
877 
878 int
879 vfs_stdsync(mp, waitfor)
880 	struct mount *mp;
881 	int waitfor;
882 {
883 	struct vnode *vp, *mvp;
884 	struct thread *td;
885 	int error, lockreq, allerror = 0;
886 
887 	td = curthread;
888 	lockreq = LK_EXCLUSIVE | LK_INTERLOCK;
889 	if (waitfor != MNT_WAIT)
890 		lockreq |= LK_NOWAIT;
891 	/*
892 	 * Force stale buffer cache information to be flushed.
893 	 */
894 	MNT_ILOCK(mp);
895 loop:
896 	MNT_VNODE_FOREACH(vp, mp, mvp) {
897 		/* bv_cnt is an acceptable race here. */
898 		if (vp->v_bufobj.bo_dirty.bv_cnt == 0)
899 			continue;
900 		VI_LOCK(vp);
901 		MNT_IUNLOCK(mp);
902 		if ((error = vget(vp, lockreq, td)) != 0) {
903 			MNT_ILOCK(mp);
904 			if (error == ENOENT) {
905 				MNT_VNODE_FOREACH_ABORT_ILOCKED(mp, mvp);
906 				goto loop;
907 			}
908 			continue;
909 		}
910 		error = VOP_FSYNC(vp, waitfor, td);
911 		if (error)
912 			allerror = error;
913 		vput(vp);
914 		MNT_ILOCK(mp);
915 	}
916 	MNT_IUNLOCK(mp);
917 	return (allerror);
918 }
919 
920 int
921 vfs_stdnosync (mp, waitfor)
922 	struct mount *mp;
923 	int waitfor;
924 {
925 
926 	return (0);
927 }
928 
929 int
930 vfs_stdvget (mp, ino, flags, vpp)
931 	struct mount *mp;
932 	ino_t ino;
933 	int flags;
934 	struct vnode **vpp;
935 {
936 
937 	return (EOPNOTSUPP);
938 }
939 
940 int
941 vfs_stdfhtovp (mp, fhp, vpp)
942 	struct mount *mp;
943 	struct fid *fhp;
944 	struct vnode **vpp;
945 {
946 
947 	return (EOPNOTSUPP);
948 }
949 
950 int
951 vfs_stdinit (vfsp)
952 	struct vfsconf *vfsp;
953 {
954 
955 	return (0);
956 }
957 
958 int
959 vfs_stduninit (vfsp)
960 	struct vfsconf *vfsp;
961 {
962 
963 	return(0);
964 }
965 
966 int
967 vfs_stdextattrctl(mp, cmd, filename_vp, attrnamespace, attrname)
968 	struct mount *mp;
969 	int cmd;
970 	struct vnode *filename_vp;
971 	int attrnamespace;
972 	const char *attrname;
973 {
974 
975 	if (filename_vp != NULL)
976 		VOP_UNLOCK(filename_vp, 0);
977 	return (EOPNOTSUPP);
978 }
979 
980 int
981 vfs_stdsysctl(mp, op, req)
982 	struct mount *mp;
983 	fsctlop_t op;
984 	struct sysctl_req *req;
985 {
986 
987 	return (EOPNOTSUPP);
988 }
989 
990 /* end of vfs default ops */
991