xref: /freebsd/sys/kern/vfs_default.c (revision b4af4f93c682e445bf159f0d1ec90b636296c946)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1989, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * This code is derived from software contributed
8  * to Berkeley by John Heidemann of the UCLA Ficus project.
9  *
10  * Source: * @(#)i405_init.c 2.10 92/04/27 UCLA Ficus project
11  *
12  * Redistribution and use in source and binary forms, with or without
13  * modification, are permitted provided that the following conditions
14  * are met:
15  * 1. Redistributions of source code must retain the above copyright
16  *    notice, this list of conditions and the following disclaimer.
17  * 2. Redistributions in binary form must reproduce the above copyright
18  *    notice, this list of conditions and the following disclaimer in the
19  *    documentation and/or other materials provided with the distribution.
20  * 3. Neither the name of the University nor the names of its contributors
21  *    may be used to endorse or promote products derived from this software
22  *    without specific prior written permission.
23  *
24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34  * SUCH DAMAGE.
35  */
36 
37 #include <sys/cdefs.h>
38 __FBSDID("$FreeBSD$");
39 
40 #include <sys/param.h>
41 #include <sys/systm.h>
42 #include <sys/bio.h>
43 #include <sys/buf.h>
44 #include <sys/conf.h>
45 #include <sys/event.h>
46 #include <sys/filio.h>
47 #include <sys/kernel.h>
48 #include <sys/limits.h>
49 #include <sys/lock.h>
50 #include <sys/lockf.h>
51 #include <sys/malloc.h>
52 #include <sys/mount.h>
53 #include <sys/namei.h>
54 #include <sys/rwlock.h>
55 #include <sys/fcntl.h>
56 #include <sys/unistd.h>
57 #include <sys/vnode.h>
58 #include <sys/dirent.h>
59 #include <sys/poll.h>
60 
61 #include <security/mac/mac_framework.h>
62 
63 #include <vm/vm.h>
64 #include <vm/vm_object.h>
65 #include <vm/vm_extern.h>
66 #include <vm/pmap.h>
67 #include <vm/vm_map.h>
68 #include <vm/vm_page.h>
69 #include <vm/vm_pager.h>
70 #include <vm/vnode_pager.h>
71 
72 static int	vop_nolookup(struct vop_lookup_args *);
73 static int	vop_norename(struct vop_rename_args *);
74 static int	vop_nostrategy(struct vop_strategy_args *);
75 static int	get_next_dirent(struct vnode *vp, struct dirent **dpp,
76 				char *dirbuf, int dirbuflen, off_t *off,
77 				char **cpos, int *len, int *eofflag,
78 				struct thread *td);
79 static int	dirent_exists(struct vnode *vp, const char *dirname,
80 			      struct thread *td);
81 
82 #define DIRENT_MINSIZE (sizeof(struct dirent) - (MAXNAMLEN+1) + 4)
83 
84 static int vop_stdis_text(struct vop_is_text_args *ap);
85 static int vop_stdunset_text(struct vop_unset_text_args *ap);
86 static int vop_stdadd_writecount(struct vop_add_writecount_args *ap);
87 static int vop_stdcopy_file_range(struct vop_copy_file_range_args *ap);
88 static int vop_stdfdatasync(struct vop_fdatasync_args *ap);
89 static int vop_stdgetpages_async(struct vop_getpages_async_args *ap);
90 
91 /*
92  * This vnode table stores what we want to do if the filesystem doesn't
93  * implement a particular VOP.
94  *
95  * If there is no specific entry here, we will return EOPNOTSUPP.
96  *
97  * Note that every filesystem has to implement either vop_access
98  * or vop_accessx; failing to do so will result in immediate crash
99  * due to stack overflow, as vop_stdaccess() calls vop_stdaccessx(),
100  * which calls vop_stdaccess() etc.
101  */
102 
103 struct vop_vector default_vnodeops = {
104 	.vop_default =		NULL,
105 	.vop_bypass =		VOP_EOPNOTSUPP,
106 
107 	.vop_access =		vop_stdaccess,
108 	.vop_accessx =		vop_stdaccessx,
109 	.vop_advise =		vop_stdadvise,
110 	.vop_advlock =		vop_stdadvlock,
111 	.vop_advlockasync =	vop_stdadvlockasync,
112 	.vop_advlockpurge =	vop_stdadvlockpurge,
113 	.vop_allocate =		vop_stdallocate,
114 	.vop_bmap =		vop_stdbmap,
115 	.vop_close =		VOP_NULL,
116 	.vop_fsync =		VOP_NULL,
117 	.vop_fdatasync =	vop_stdfdatasync,
118 	.vop_getpages =		vop_stdgetpages,
119 	.vop_getpages_async =	vop_stdgetpages_async,
120 	.vop_getwritemount = 	vop_stdgetwritemount,
121 	.vop_inactive =		VOP_NULL,
122 	.vop_need_inactive =	vop_stdneed_inactive,
123 	.vop_ioctl =		vop_stdioctl,
124 	.vop_kqfilter =		vop_stdkqfilter,
125 	.vop_islocked =		vop_stdislocked,
126 	.vop_lock1 =		vop_stdlock,
127 	.vop_lookup =		vop_nolookup,
128 	.vop_open =		VOP_NULL,
129 	.vop_pathconf =		VOP_EINVAL,
130 	.vop_poll =		vop_nopoll,
131 	.vop_putpages =		vop_stdputpages,
132 	.vop_readlink =		VOP_EINVAL,
133 	.vop_rename =		vop_norename,
134 	.vop_revoke =		VOP_PANIC,
135 	.vop_strategy =		vop_nostrategy,
136 	.vop_unlock =		vop_stdunlock,
137 	.vop_vptocnp =		vop_stdvptocnp,
138 	.vop_vptofh =		vop_stdvptofh,
139 	.vop_unp_bind =		vop_stdunp_bind,
140 	.vop_unp_connect =	vop_stdunp_connect,
141 	.vop_unp_detach =	vop_stdunp_detach,
142 	.vop_is_text =		vop_stdis_text,
143 	.vop_set_text =		vop_stdset_text,
144 	.vop_unset_text =	vop_stdunset_text,
145 	.vop_add_writecount =	vop_stdadd_writecount,
146 	.vop_copy_file_range =	vop_stdcopy_file_range,
147 };
148 VFS_VOP_VECTOR_REGISTER(default_vnodeops);
149 
150 /*
151  * Series of placeholder functions for various error returns for
152  * VOPs.
153  */
154 
155 int
156 vop_eopnotsupp(struct vop_generic_args *ap)
157 {
158 	/*
159 	printf("vop_notsupp[%s]\n", ap->a_desc->vdesc_name);
160 	*/
161 
162 	return (EOPNOTSUPP);
163 }
164 
165 int
166 vop_ebadf(struct vop_generic_args *ap)
167 {
168 
169 	return (EBADF);
170 }
171 
172 int
173 vop_enotty(struct vop_generic_args *ap)
174 {
175 
176 	return (ENOTTY);
177 }
178 
179 int
180 vop_einval(struct vop_generic_args *ap)
181 {
182 
183 	return (EINVAL);
184 }
185 
186 int
187 vop_enoent(struct vop_generic_args *ap)
188 {
189 
190 	return (ENOENT);
191 }
192 
193 int
194 vop_null(struct vop_generic_args *ap)
195 {
196 
197 	return (0);
198 }
199 
200 /*
201  * Helper function to panic on some bad VOPs in some filesystems.
202  */
203 int
204 vop_panic(struct vop_generic_args *ap)
205 {
206 
207 	panic("filesystem goof: vop_panic[%s]", ap->a_desc->vdesc_name);
208 }
209 
210 /*
211  * vop_std<something> and vop_no<something> are default functions for use by
212  * filesystems that need the "default reasonable" implementation for a
213  * particular operation.
214  *
215  * The documentation for the operations they implement exists (if it exists)
216  * in the VOP_<SOMETHING>(9) manpage (all uppercase).
217  */
218 
219 /*
220  * Default vop for filesystems that do not support name lookup
221  */
222 static int
223 vop_nolookup(ap)
224 	struct vop_lookup_args /* {
225 		struct vnode *a_dvp;
226 		struct vnode **a_vpp;
227 		struct componentname *a_cnp;
228 	} */ *ap;
229 {
230 
231 	*ap->a_vpp = NULL;
232 	return (ENOTDIR);
233 }
234 
235 /*
236  * vop_norename:
237  *
238  * Handle unlock and reference counting for arguments of vop_rename
239  * for filesystems that do not implement rename operation.
240  */
241 static int
242 vop_norename(struct vop_rename_args *ap)
243 {
244 
245 	vop_rename_fail(ap);
246 	return (EOPNOTSUPP);
247 }
248 
249 /*
250  *	vop_nostrategy:
251  *
252  *	Strategy routine for VFS devices that have none.
253  *
254  *	BIO_ERROR and B_INVAL must be cleared prior to calling any strategy
255  *	routine.  Typically this is done for a BIO_READ strategy call.
256  *	Typically B_INVAL is assumed to already be clear prior to a write
257  *	and should not be cleared manually unless you just made the buffer
258  *	invalid.  BIO_ERROR should be cleared either way.
259  */
260 
261 static int
262 vop_nostrategy (struct vop_strategy_args *ap)
263 {
264 	printf("No strategy for buffer at %p\n", ap->a_bp);
265 	vn_printf(ap->a_vp, "vnode ");
266 	ap->a_bp->b_ioflags |= BIO_ERROR;
267 	ap->a_bp->b_error = EOPNOTSUPP;
268 	bufdone(ap->a_bp);
269 	return (EOPNOTSUPP);
270 }
271 
272 static int
273 get_next_dirent(struct vnode *vp, struct dirent **dpp, char *dirbuf,
274 		int dirbuflen, off_t *off, char **cpos, int *len,
275 		int *eofflag, struct thread *td)
276 {
277 	int error, reclen;
278 	struct uio uio;
279 	struct iovec iov;
280 	struct dirent *dp;
281 
282 	KASSERT(VOP_ISLOCKED(vp), ("vp %p is not locked", vp));
283 	KASSERT(vp->v_type == VDIR, ("vp %p is not a directory", vp));
284 
285 	if (*len == 0) {
286 		iov.iov_base = dirbuf;
287 		iov.iov_len = dirbuflen;
288 
289 		uio.uio_iov = &iov;
290 		uio.uio_iovcnt = 1;
291 		uio.uio_offset = *off;
292 		uio.uio_resid = dirbuflen;
293 		uio.uio_segflg = UIO_SYSSPACE;
294 		uio.uio_rw = UIO_READ;
295 		uio.uio_td = td;
296 
297 		*eofflag = 0;
298 
299 #ifdef MAC
300 		error = mac_vnode_check_readdir(td->td_ucred, vp);
301 		if (error == 0)
302 #endif
303 			error = VOP_READDIR(vp, &uio, td->td_ucred, eofflag,
304 		    		NULL, NULL);
305 		if (error)
306 			return (error);
307 
308 		*off = uio.uio_offset;
309 
310 		*cpos = dirbuf;
311 		*len = (dirbuflen - uio.uio_resid);
312 
313 		if (*len == 0)
314 			return (ENOENT);
315 	}
316 
317 	dp = (struct dirent *)(*cpos);
318 	reclen = dp->d_reclen;
319 	*dpp = dp;
320 
321 	/* check for malformed directory.. */
322 	if (reclen < DIRENT_MINSIZE)
323 		return (EINVAL);
324 
325 	*cpos += reclen;
326 	*len -= reclen;
327 
328 	return (0);
329 }
330 
331 /*
332  * Check if a named file exists in a given directory vnode.
333  */
334 static int
335 dirent_exists(struct vnode *vp, const char *dirname, struct thread *td)
336 {
337 	char *dirbuf, *cpos;
338 	int error, eofflag, dirbuflen, len, found;
339 	off_t off;
340 	struct dirent *dp;
341 	struct vattr va;
342 
343 	KASSERT(VOP_ISLOCKED(vp), ("vp %p is not locked", vp));
344 	KASSERT(vp->v_type == VDIR, ("vp %p is not a directory", vp));
345 
346 	found = 0;
347 
348 	error = VOP_GETATTR(vp, &va, td->td_ucred);
349 	if (error)
350 		return (found);
351 
352 	dirbuflen = DEV_BSIZE;
353 	if (dirbuflen < va.va_blocksize)
354 		dirbuflen = va.va_blocksize;
355 	dirbuf = (char *)malloc(dirbuflen, M_TEMP, M_WAITOK);
356 
357 	off = 0;
358 	len = 0;
359 	do {
360 		error = get_next_dirent(vp, &dp, dirbuf, dirbuflen, &off,
361 					&cpos, &len, &eofflag, td);
362 		if (error)
363 			goto out;
364 
365 		if (dp->d_type != DT_WHT && dp->d_fileno != 0 &&
366 		    strcmp(dp->d_name, dirname) == 0) {
367 			found = 1;
368 			goto out;
369 		}
370 	} while (len > 0 || !eofflag);
371 
372 out:
373 	free(dirbuf, M_TEMP);
374 	return (found);
375 }
376 
377 int
378 vop_stdaccess(struct vop_access_args *ap)
379 {
380 
381 	KASSERT((ap->a_accmode & ~(VEXEC | VWRITE | VREAD | VADMIN |
382 	    VAPPEND)) == 0, ("invalid bit in accmode"));
383 
384 	return (VOP_ACCESSX(ap->a_vp, ap->a_accmode, ap->a_cred, ap->a_td));
385 }
386 
387 int
388 vop_stdaccessx(struct vop_accessx_args *ap)
389 {
390 	int error;
391 	accmode_t accmode = ap->a_accmode;
392 
393 	error = vfs_unixify_accmode(&accmode);
394 	if (error != 0)
395 		return (error);
396 
397 	if (accmode == 0)
398 		return (0);
399 
400 	return (VOP_ACCESS(ap->a_vp, accmode, ap->a_cred, ap->a_td));
401 }
402 
403 /*
404  * Advisory record locking support
405  */
406 int
407 vop_stdadvlock(struct vop_advlock_args *ap)
408 {
409 	struct vnode *vp;
410 	struct vattr vattr;
411 	int error;
412 
413 	vp = ap->a_vp;
414 	if (ap->a_fl->l_whence == SEEK_END) {
415 		/*
416 		 * The NFSv4 server must avoid doing a vn_lock() here, since it
417 		 * can deadlock the nfsd threads, due to a LOR.  Fortunately
418 		 * the NFSv4 server always uses SEEK_SET and this code is
419 		 * only required for the SEEK_END case.
420 		 */
421 		vn_lock(vp, LK_SHARED | LK_RETRY);
422 		error = VOP_GETATTR(vp, &vattr, curthread->td_ucred);
423 		VOP_UNLOCK(vp);
424 		if (error)
425 			return (error);
426 	} else
427 		vattr.va_size = 0;
428 
429 	return (lf_advlock(ap, &(vp->v_lockf), vattr.va_size));
430 }
431 
432 int
433 vop_stdadvlockasync(struct vop_advlockasync_args *ap)
434 {
435 	struct vnode *vp;
436 	struct vattr vattr;
437 	int error;
438 
439 	vp = ap->a_vp;
440 	if (ap->a_fl->l_whence == SEEK_END) {
441 		/* The size argument is only needed for SEEK_END. */
442 		vn_lock(vp, LK_SHARED | LK_RETRY);
443 		error = VOP_GETATTR(vp, &vattr, curthread->td_ucred);
444 		VOP_UNLOCK(vp);
445 		if (error)
446 			return (error);
447 	} else
448 		vattr.va_size = 0;
449 
450 	return (lf_advlockasync(ap, &(vp->v_lockf), vattr.va_size));
451 }
452 
453 int
454 vop_stdadvlockpurge(struct vop_advlockpurge_args *ap)
455 {
456 	struct vnode *vp;
457 
458 	vp = ap->a_vp;
459 	lf_purgelocks(vp, &vp->v_lockf);
460 	return (0);
461 }
462 
463 /*
464  * vop_stdpathconf:
465  *
466  * Standard implementation of POSIX pathconf, to get information about limits
467  * for a filesystem.
468  * Override per filesystem for the case where the filesystem has smaller
469  * limits.
470  */
471 int
472 vop_stdpathconf(ap)
473 	struct vop_pathconf_args /* {
474 	struct vnode *a_vp;
475 	int a_name;
476 	int *a_retval;
477 	} */ *ap;
478 {
479 
480 	switch (ap->a_name) {
481 		case _PC_ASYNC_IO:
482 			*ap->a_retval = _POSIX_ASYNCHRONOUS_IO;
483 			return (0);
484 		case _PC_PATH_MAX:
485 			*ap->a_retval = PATH_MAX;
486 			return (0);
487 		case _PC_ACL_EXTENDED:
488 		case _PC_ACL_NFS4:
489 		case _PC_CAP_PRESENT:
490 		case _PC_INF_PRESENT:
491 		case _PC_MAC_PRESENT:
492 			*ap->a_retval = 0;
493 			return (0);
494 		default:
495 			return (EINVAL);
496 	}
497 	/* NOTREACHED */
498 }
499 
500 /*
501  * Standard lock, unlock and islocked functions.
502  */
503 int
504 vop_stdlock(ap)
505 	struct vop_lock1_args /* {
506 		struct vnode *a_vp;
507 		int a_flags;
508 		char *file;
509 		int line;
510 	} */ *ap;
511 {
512 	struct vnode *vp = ap->a_vp;
513 	struct mtx *ilk;
514 
515 	ilk = VI_MTX(vp);
516 	return (lockmgr_lock_flags(vp->v_vnlock, ap->a_flags,
517 	    &ilk->lock_object, ap->a_file, ap->a_line));
518 }
519 
520 /* See above. */
521 int
522 vop_stdunlock(ap)
523 	struct vop_unlock_args /* {
524 		struct vnode *a_vp;
525 	} */ *ap;
526 {
527 	struct vnode *vp = ap->a_vp;
528 
529 	return (lockmgr_unlock(vp->v_vnlock));
530 }
531 
532 /* See above. */
533 int
534 vop_stdislocked(ap)
535 	struct vop_islocked_args /* {
536 		struct vnode *a_vp;
537 	} */ *ap;
538 {
539 
540 	return (lockstatus(ap->a_vp->v_vnlock));
541 }
542 
543 /*
544  * Variants of the above set.
545  *
546  * Differences are:
547  * - shared locking disablement is not supported
548  * - v_vnlock pointer is not honored
549  */
550 int
551 vop_lock(ap)
552 	struct vop_lock1_args /* {
553 		struct vnode *a_vp;
554 		int a_flags;
555 		char *file;
556 		int line;
557 	} */ *ap;
558 {
559 	struct vnode *vp = ap->a_vp;
560 	int flags = ap->a_flags;
561 	struct mtx *ilk;
562 
563 	MPASS(vp->v_vnlock == &vp->v_lock);
564 
565 	if (__predict_false((flags & ~(LK_TYPE_MASK | LK_NODDLKTREAT | LK_RETRY)) != 0))
566 		goto other;
567 
568 	switch (flags & LK_TYPE_MASK) {
569 	case LK_SHARED:
570 		return (lockmgr_slock(&vp->v_lock, flags, ap->a_file, ap->a_line));
571 	case LK_EXCLUSIVE:
572 		return (lockmgr_xlock(&vp->v_lock, flags, ap->a_file, ap->a_line));
573 	}
574 other:
575 	ilk = VI_MTX(vp);
576 	return (lockmgr_lock_flags(&vp->v_lock, flags,
577 	    &ilk->lock_object, ap->a_file, ap->a_line));
578 }
579 
580 int
581 vop_unlock(ap)
582 	struct vop_unlock_args /* {
583 		struct vnode *a_vp;
584 	} */ *ap;
585 {
586 	struct vnode *vp = ap->a_vp;
587 
588 	MPASS(vp->v_vnlock == &vp->v_lock);
589 
590 	return (lockmgr_unlock(&vp->v_lock));
591 }
592 
593 int
594 vop_islocked(ap)
595 	struct vop_islocked_args /* {
596 		struct vnode *a_vp;
597 	} */ *ap;
598 {
599 	struct vnode *vp = ap->a_vp;
600 
601 	MPASS(vp->v_vnlock == &vp->v_lock);
602 
603 	return (lockstatus(&vp->v_lock));
604 }
605 
606 /*
607  * Return true for select/poll.
608  */
609 int
610 vop_nopoll(ap)
611 	struct vop_poll_args /* {
612 		struct vnode *a_vp;
613 		int  a_events;
614 		struct ucred *a_cred;
615 		struct thread *a_td;
616 	} */ *ap;
617 {
618 
619 	if (ap->a_events & ~POLLSTANDARD)
620 		return (POLLNVAL);
621 	return (ap->a_events & (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM));
622 }
623 
624 /*
625  * Implement poll for local filesystems that support it.
626  */
627 int
628 vop_stdpoll(ap)
629 	struct vop_poll_args /* {
630 		struct vnode *a_vp;
631 		int  a_events;
632 		struct ucred *a_cred;
633 		struct thread *a_td;
634 	} */ *ap;
635 {
636 	if (ap->a_events & ~POLLSTANDARD)
637 		return (vn_pollrecord(ap->a_vp, ap->a_td, ap->a_events));
638 	return (ap->a_events & (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM));
639 }
640 
641 /*
642  * Return our mount point, as we will take charge of the writes.
643  */
644 int
645 vop_stdgetwritemount(ap)
646 	struct vop_getwritemount_args /* {
647 		struct vnode *a_vp;
648 		struct mount **a_mpp;
649 	} */ *ap;
650 {
651 	struct mount *mp;
652 	struct vnode *vp;
653 
654 	/*
655 	 * Note that having a reference does not prevent forced unmount from
656 	 * setting ->v_mount to NULL after the lock gets released. This is of
657 	 * no consequence for typical consumers (most notably vn_start_write)
658 	 * since in this case the vnode is VIRF_DOOMED. Unmount might have
659 	 * progressed far enough that its completion is only delayed by the
660 	 * reference obtained here. The consumer only needs to concern itself
661 	 * with releasing it.
662 	 */
663 	vp = ap->a_vp;
664 	mp = vp->v_mount;
665 	if (mp == NULL) {
666 		*(ap->a_mpp) = NULL;
667 		return (0);
668 	}
669 	if (vfs_op_thread_enter(mp)) {
670 		if (mp == vp->v_mount) {
671 			vfs_mp_count_add_pcpu(mp, ref, 1);
672 			vfs_op_thread_exit(mp);
673 		} else {
674 			vfs_op_thread_exit(mp);
675 			mp = NULL;
676 		}
677 	} else {
678 		MNT_ILOCK(mp);
679 		if (mp == vp->v_mount) {
680 			MNT_REF(mp);
681 			MNT_IUNLOCK(mp);
682 		} else {
683 			MNT_IUNLOCK(mp);
684 			mp = NULL;
685 		}
686 	}
687 	*(ap->a_mpp) = mp;
688 	return (0);
689 }
690 
691 /*
692  * If the file system doesn't implement VOP_BMAP, then return sensible defaults:
693  * - Return the vnode's bufobj instead of any underlying device's bufobj
694  * - Calculate the physical block number as if there were equal size
695  *   consecutive blocks, but
696  * - Report no contiguous runs of blocks.
697  */
698 int
699 vop_stdbmap(ap)
700 	struct vop_bmap_args /* {
701 		struct vnode *a_vp;
702 		daddr_t  a_bn;
703 		struct bufobj **a_bop;
704 		daddr_t *a_bnp;
705 		int *a_runp;
706 		int *a_runb;
707 	} */ *ap;
708 {
709 
710 	if (ap->a_bop != NULL)
711 		*ap->a_bop = &ap->a_vp->v_bufobj;
712 	if (ap->a_bnp != NULL)
713 		*ap->a_bnp = ap->a_bn * btodb(ap->a_vp->v_mount->mnt_stat.f_iosize);
714 	if (ap->a_runp != NULL)
715 		*ap->a_runp = 0;
716 	if (ap->a_runb != NULL)
717 		*ap->a_runb = 0;
718 	return (0);
719 }
720 
721 int
722 vop_stdfsync(ap)
723 	struct vop_fsync_args /* {
724 		struct vnode *a_vp;
725 		int a_waitfor;
726 		struct thread *a_td;
727 	} */ *ap;
728 {
729 
730 	return (vn_fsync_buf(ap->a_vp, ap->a_waitfor));
731 }
732 
733 static int
734 vop_stdfdatasync(struct vop_fdatasync_args *ap)
735 {
736 
737 	return (VOP_FSYNC(ap->a_vp, MNT_WAIT, ap->a_td));
738 }
739 
740 int
741 vop_stdfdatasync_buf(struct vop_fdatasync_args *ap)
742 {
743 
744 	return (vn_fsync_buf(ap->a_vp, MNT_WAIT));
745 }
746 
747 /* XXX Needs good comment and more info in the manpage (VOP_GETPAGES(9)). */
748 int
749 vop_stdgetpages(ap)
750 	struct vop_getpages_args /* {
751 		struct vnode *a_vp;
752 		vm_page_t *a_m;
753 		int a_count;
754 		int *a_rbehind;
755 		int *a_rahead;
756 	} */ *ap;
757 {
758 
759 	return vnode_pager_generic_getpages(ap->a_vp, ap->a_m,
760 	    ap->a_count, ap->a_rbehind, ap->a_rahead, NULL, NULL);
761 }
762 
763 static int
764 vop_stdgetpages_async(struct vop_getpages_async_args *ap)
765 {
766 	int error;
767 
768 	error = VOP_GETPAGES(ap->a_vp, ap->a_m, ap->a_count, ap->a_rbehind,
769 	    ap->a_rahead);
770 	if (ap->a_iodone != NULL)
771 		ap->a_iodone(ap->a_arg, ap->a_m, ap->a_count, error);
772 	return (error);
773 }
774 
775 int
776 vop_stdkqfilter(struct vop_kqfilter_args *ap)
777 {
778 	return vfs_kqfilter(ap);
779 }
780 
781 /* XXX Needs good comment and more info in the manpage (VOP_PUTPAGES(9)). */
782 int
783 vop_stdputpages(ap)
784 	struct vop_putpages_args /* {
785 		struct vnode *a_vp;
786 		vm_page_t *a_m;
787 		int a_count;
788 		int a_sync;
789 		int *a_rtvals;
790 	} */ *ap;
791 {
792 
793 	return vnode_pager_generic_putpages(ap->a_vp, ap->a_m, ap->a_count,
794 	     ap->a_sync, ap->a_rtvals);
795 }
796 
797 int
798 vop_stdvptofh(struct vop_vptofh_args *ap)
799 {
800 	return (EOPNOTSUPP);
801 }
802 
803 int
804 vop_stdvptocnp(struct vop_vptocnp_args *ap)
805 {
806 	struct vnode *vp = ap->a_vp;
807 	struct vnode **dvp = ap->a_vpp;
808 	struct ucred *cred = ap->a_cred;
809 	char *buf = ap->a_buf;
810 	size_t *buflen = ap->a_buflen;
811 	char *dirbuf, *cpos;
812 	int i, error, eofflag, dirbuflen, flags, locked, len, covered;
813 	off_t off;
814 	ino_t fileno;
815 	struct vattr va;
816 	struct nameidata nd;
817 	struct thread *td;
818 	struct dirent *dp;
819 	struct vnode *mvp;
820 
821 	i = *buflen;
822 	error = 0;
823 	covered = 0;
824 	td = curthread;
825 
826 	if (vp->v_type != VDIR)
827 		return (ENOENT);
828 
829 	error = VOP_GETATTR(vp, &va, cred);
830 	if (error)
831 		return (error);
832 
833 	VREF(vp);
834 	locked = VOP_ISLOCKED(vp);
835 	VOP_UNLOCK(vp);
836 	NDINIT_ATVP(&nd, LOOKUP, FOLLOW | LOCKSHARED | LOCKLEAF, UIO_SYSSPACE,
837 	    "..", vp, td);
838 	flags = FREAD;
839 	error = vn_open_cred(&nd, &flags, 0, VN_OPEN_NOAUDIT, cred, NULL);
840 	if (error) {
841 		vn_lock(vp, locked | LK_RETRY);
842 		return (error);
843 	}
844 	NDFREE(&nd, NDF_ONLY_PNBUF);
845 
846 	mvp = *dvp = nd.ni_vp;
847 
848 	if (vp->v_mount != (*dvp)->v_mount &&
849 	    ((*dvp)->v_vflag & VV_ROOT) &&
850 	    ((*dvp)->v_mount->mnt_flag & MNT_UNION)) {
851 		*dvp = (*dvp)->v_mount->mnt_vnodecovered;
852 		VREF(mvp);
853 		VOP_UNLOCK(mvp);
854 		vn_close(mvp, FREAD, cred, td);
855 		VREF(*dvp);
856 		vn_lock(*dvp, LK_SHARED | LK_RETRY);
857 		covered = 1;
858 	}
859 
860 	fileno = va.va_fileid;
861 
862 	dirbuflen = DEV_BSIZE;
863 	if (dirbuflen < va.va_blocksize)
864 		dirbuflen = va.va_blocksize;
865 	dirbuf = (char *)malloc(dirbuflen, M_TEMP, M_WAITOK);
866 
867 	if ((*dvp)->v_type != VDIR) {
868 		error = ENOENT;
869 		goto out;
870 	}
871 
872 	off = 0;
873 	len = 0;
874 	do {
875 		/* call VOP_READDIR of parent */
876 		error = get_next_dirent(*dvp, &dp, dirbuf, dirbuflen, &off,
877 					&cpos, &len, &eofflag, td);
878 		if (error)
879 			goto out;
880 
881 		if ((dp->d_type != DT_WHT) &&
882 		    (dp->d_fileno == fileno)) {
883 			if (covered) {
884 				VOP_UNLOCK(*dvp);
885 				vn_lock(mvp, LK_SHARED | LK_RETRY);
886 				if (dirent_exists(mvp, dp->d_name, td)) {
887 					error = ENOENT;
888 					VOP_UNLOCK(mvp);
889 					vn_lock(*dvp, LK_SHARED | LK_RETRY);
890 					goto out;
891 				}
892 				VOP_UNLOCK(mvp);
893 				vn_lock(*dvp, LK_SHARED | LK_RETRY);
894 			}
895 			i -= dp->d_namlen;
896 
897 			if (i < 0) {
898 				error = ENOMEM;
899 				goto out;
900 			}
901 			if (dp->d_namlen == 1 && dp->d_name[0] == '.') {
902 				error = ENOENT;
903 			} else {
904 				bcopy(dp->d_name, buf + i, dp->d_namlen);
905 				error = 0;
906 			}
907 			goto out;
908 		}
909 	} while (len > 0 || !eofflag);
910 	error = ENOENT;
911 
912 out:
913 	free(dirbuf, M_TEMP);
914 	if (!error) {
915 		*buflen = i;
916 		vref(*dvp);
917 	}
918 	if (covered) {
919 		vput(*dvp);
920 		vrele(mvp);
921 	} else {
922 		VOP_UNLOCK(mvp);
923 		vn_close(mvp, FREAD, cred, td);
924 	}
925 	vn_lock(vp, locked | LK_RETRY);
926 	return (error);
927 }
928 
929 int
930 vop_stdallocate(struct vop_allocate_args *ap)
931 {
932 #ifdef __notyet__
933 	struct statfs *sfs;
934 	off_t maxfilesize = 0;
935 #endif
936 	struct iovec aiov;
937 	struct vattr vattr, *vap;
938 	struct uio auio;
939 	off_t fsize, len, cur, offset;
940 	uint8_t *buf;
941 	struct thread *td;
942 	struct vnode *vp;
943 	size_t iosize;
944 	int error;
945 
946 	buf = NULL;
947 	error = 0;
948 	td = curthread;
949 	vap = &vattr;
950 	vp = ap->a_vp;
951 	len = *ap->a_len;
952 	offset = *ap->a_offset;
953 
954 	error = VOP_GETATTR(vp, vap, td->td_ucred);
955 	if (error != 0)
956 		goto out;
957 	fsize = vap->va_size;
958 	iosize = vap->va_blocksize;
959 	if (iosize == 0)
960 		iosize = BLKDEV_IOSIZE;
961 	if (iosize > MAXPHYS)
962 		iosize = MAXPHYS;
963 	buf = malloc(iosize, M_TEMP, M_WAITOK);
964 
965 #ifdef __notyet__
966 	/*
967 	 * Check if the filesystem sets f_maxfilesize; if not use
968 	 * VOP_SETATTR to perform the check.
969 	 */
970 	sfs = malloc(sizeof(struct statfs), M_STATFS, M_WAITOK);
971 	error = VFS_STATFS(vp->v_mount, sfs, td);
972 	if (error == 0)
973 		maxfilesize = sfs->f_maxfilesize;
974 	free(sfs, M_STATFS);
975 	if (error != 0)
976 		goto out;
977 	if (maxfilesize) {
978 		if (offset > maxfilesize || len > maxfilesize ||
979 		    offset + len > maxfilesize) {
980 			error = EFBIG;
981 			goto out;
982 		}
983 	} else
984 #endif
985 	if (offset + len > vap->va_size) {
986 		/*
987 		 * Test offset + len against the filesystem's maxfilesize.
988 		 */
989 		VATTR_NULL(vap);
990 		vap->va_size = offset + len;
991 		error = VOP_SETATTR(vp, vap, td->td_ucred);
992 		if (error != 0)
993 			goto out;
994 		VATTR_NULL(vap);
995 		vap->va_size = fsize;
996 		error = VOP_SETATTR(vp, vap, td->td_ucred);
997 		if (error != 0)
998 			goto out;
999 	}
1000 
1001 	for (;;) {
1002 		/*
1003 		 * Read and write back anything below the nominal file
1004 		 * size.  There's currently no way outside the filesystem
1005 		 * to know whether this area is sparse or not.
1006 		 */
1007 		cur = iosize;
1008 		if ((offset % iosize) != 0)
1009 			cur -= (offset % iosize);
1010 		if (cur > len)
1011 			cur = len;
1012 		if (offset < fsize) {
1013 			aiov.iov_base = buf;
1014 			aiov.iov_len = cur;
1015 			auio.uio_iov = &aiov;
1016 			auio.uio_iovcnt = 1;
1017 			auio.uio_offset = offset;
1018 			auio.uio_resid = cur;
1019 			auio.uio_segflg = UIO_SYSSPACE;
1020 			auio.uio_rw = UIO_READ;
1021 			auio.uio_td = td;
1022 			error = VOP_READ(vp, &auio, 0, td->td_ucred);
1023 			if (error != 0)
1024 				break;
1025 			if (auio.uio_resid > 0) {
1026 				bzero(buf + cur - auio.uio_resid,
1027 				    auio.uio_resid);
1028 			}
1029 		} else {
1030 			bzero(buf, cur);
1031 		}
1032 
1033 		aiov.iov_base = buf;
1034 		aiov.iov_len = cur;
1035 		auio.uio_iov = &aiov;
1036 		auio.uio_iovcnt = 1;
1037 		auio.uio_offset = offset;
1038 		auio.uio_resid = cur;
1039 		auio.uio_segflg = UIO_SYSSPACE;
1040 		auio.uio_rw = UIO_WRITE;
1041 		auio.uio_td = td;
1042 
1043 		error = VOP_WRITE(vp, &auio, 0, td->td_ucred);
1044 		if (error != 0)
1045 			break;
1046 
1047 		len -= cur;
1048 		offset += cur;
1049 		if (len == 0)
1050 			break;
1051 		if (should_yield())
1052 			break;
1053 	}
1054 
1055  out:
1056 	*ap->a_len = len;
1057 	*ap->a_offset = offset;
1058 	free(buf, M_TEMP);
1059 	return (error);
1060 }
1061 
1062 int
1063 vop_stdadvise(struct vop_advise_args *ap)
1064 {
1065 	struct vnode *vp;
1066 	struct bufobj *bo;
1067 	daddr_t startn, endn;
1068 	off_t bstart, bend, start, end;
1069 	int bsize, error;
1070 
1071 	vp = ap->a_vp;
1072 	switch (ap->a_advice) {
1073 	case POSIX_FADV_WILLNEED:
1074 		/*
1075 		 * Do nothing for now.  Filesystems should provide a
1076 		 * custom method which starts an asynchronous read of
1077 		 * the requested region.
1078 		 */
1079 		error = 0;
1080 		break;
1081 	case POSIX_FADV_DONTNEED:
1082 		error = 0;
1083 		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
1084 		if (VN_IS_DOOMED(vp)) {
1085 			VOP_UNLOCK(vp);
1086 			break;
1087 		}
1088 
1089 		/*
1090 		 * Round to block boundaries (and later possibly further to
1091 		 * page boundaries).  Applications cannot reasonably be aware
1092 		 * of the boundaries, and the rounding must be to expand at
1093 		 * both extremities to cover enough.  It still doesn't cover
1094 		 * read-ahead.  For partial blocks, this gives unnecessary
1095 		 * discarding of buffers but is efficient enough since the
1096 		 * pages usually remain in VMIO for some time.
1097 		 */
1098 		bsize = vp->v_bufobj.bo_bsize;
1099 		bstart = rounddown(ap->a_start, bsize);
1100 		bend = roundup(ap->a_end, bsize);
1101 
1102 		/*
1103 		 * Deactivate pages in the specified range from the backing VM
1104 		 * object.  Pages that are resident in the buffer cache will
1105 		 * remain wired until their corresponding buffers are released
1106 		 * below.
1107 		 */
1108 		if (vp->v_object != NULL) {
1109 			start = trunc_page(bstart);
1110 			end = round_page(bend);
1111 			VM_OBJECT_RLOCK(vp->v_object);
1112 			vm_object_page_noreuse(vp->v_object, OFF_TO_IDX(start),
1113 			    OFF_TO_IDX(end));
1114 			VM_OBJECT_RUNLOCK(vp->v_object);
1115 		}
1116 
1117 		bo = &vp->v_bufobj;
1118 		BO_RLOCK(bo);
1119 		startn = bstart / bsize;
1120 		endn = bend / bsize;
1121 		error = bnoreuselist(&bo->bo_clean, bo, startn, endn);
1122 		if (error == 0)
1123 			error = bnoreuselist(&bo->bo_dirty, bo, startn, endn);
1124 		BO_RUNLOCK(bo);
1125 		VOP_UNLOCK(vp);
1126 		break;
1127 	default:
1128 		error = EINVAL;
1129 		break;
1130 	}
1131 	return (error);
1132 }
1133 
1134 int
1135 vop_stdunp_bind(struct vop_unp_bind_args *ap)
1136 {
1137 
1138 	ap->a_vp->v_unpcb = ap->a_unpcb;
1139 	return (0);
1140 }
1141 
1142 int
1143 vop_stdunp_connect(struct vop_unp_connect_args *ap)
1144 {
1145 
1146 	*ap->a_unpcb = ap->a_vp->v_unpcb;
1147 	return (0);
1148 }
1149 
1150 int
1151 vop_stdunp_detach(struct vop_unp_detach_args *ap)
1152 {
1153 
1154 	ap->a_vp->v_unpcb = NULL;
1155 	return (0);
1156 }
1157 
1158 static int
1159 vop_stdis_text(struct vop_is_text_args *ap)
1160 {
1161 
1162 	return (ap->a_vp->v_writecount < 0);
1163 }
1164 
1165 int
1166 vop_stdset_text(struct vop_set_text_args *ap)
1167 {
1168 	struct vnode *vp;
1169 	struct mount *mp;
1170 	int error;
1171 
1172 	vp = ap->a_vp;
1173 	VI_LOCK(vp);
1174 	if (vp->v_writecount > 0) {
1175 		error = ETXTBSY;
1176 	} else {
1177 		/*
1178 		 * If requested by fs, keep a use reference to the
1179 		 * vnode until the last text reference is released.
1180 		 */
1181 		mp = vp->v_mount;
1182 		if (mp != NULL && (mp->mnt_kern_flag & MNTK_TEXT_REFS) != 0 &&
1183 		    vp->v_writecount == 0) {
1184 			vp->v_iflag |= VI_TEXT_REF;
1185 			vrefl(vp);
1186 		}
1187 
1188 		vp->v_writecount--;
1189 		error = 0;
1190 	}
1191 	VI_UNLOCK(vp);
1192 	return (error);
1193 }
1194 
1195 static int
1196 vop_stdunset_text(struct vop_unset_text_args *ap)
1197 {
1198 	struct vnode *vp;
1199 	int error;
1200 	bool last;
1201 
1202 	vp = ap->a_vp;
1203 	last = false;
1204 	VI_LOCK(vp);
1205 	if (vp->v_writecount < 0) {
1206 		if ((vp->v_iflag & VI_TEXT_REF) != 0 &&
1207 		    vp->v_writecount == -1) {
1208 			last = true;
1209 			vp->v_iflag &= ~VI_TEXT_REF;
1210 		}
1211 		vp->v_writecount++;
1212 		error = 0;
1213 	} else {
1214 		error = EINVAL;
1215 	}
1216 	VI_UNLOCK(vp);
1217 	if (last)
1218 		vunref(vp);
1219 	return (error);
1220 }
1221 
1222 static int
1223 vop_stdadd_writecount(struct vop_add_writecount_args *ap)
1224 {
1225 	struct vnode *vp;
1226 	struct mount *mp;
1227 	int error;
1228 
1229 	vp = ap->a_vp;
1230 	VI_LOCK_FLAGS(vp, MTX_DUPOK);
1231 	if (vp->v_writecount < 0) {
1232 		error = ETXTBSY;
1233 	} else {
1234 		VNASSERT(vp->v_writecount + ap->a_inc >= 0, vp,
1235 		    ("neg writecount increment %d", ap->a_inc));
1236 		if (vp->v_writecount == 0) {
1237 			mp = vp->v_mount;
1238 			if (mp != NULL && (mp->mnt_kern_flag & MNTK_NOMSYNC) == 0)
1239 				vlazy(vp);
1240 		}
1241 		vp->v_writecount += ap->a_inc;
1242 		error = 0;
1243 	}
1244 	VI_UNLOCK(vp);
1245 	return (error);
1246 }
1247 
1248 int
1249 vop_stdneed_inactive(struct vop_need_inactive_args *ap)
1250 {
1251 
1252 	return (1);
1253 }
1254 
1255 int
1256 vop_stdioctl(struct vop_ioctl_args *ap)
1257 {
1258 	struct vnode *vp;
1259 	struct vattr va;
1260 	off_t *offp;
1261 	int error;
1262 
1263 	switch (ap->a_command) {
1264 	case FIOSEEKDATA:
1265 	case FIOSEEKHOLE:
1266 		vp = ap->a_vp;
1267 		error = vn_lock(vp, LK_SHARED);
1268 		if (error != 0)
1269 			return (EBADF);
1270 		if (vp->v_type == VREG)
1271 			error = VOP_GETATTR(vp, &va, ap->a_cred);
1272 		else
1273 			error = ENOTTY;
1274 		if (error == 0) {
1275 			offp = ap->a_data;
1276 			if (*offp < 0 || *offp >= va.va_size)
1277 				error = ENXIO;
1278 			else if (ap->a_command == FIOSEEKHOLE)
1279 				*offp = va.va_size;
1280 		}
1281 		VOP_UNLOCK(vp);
1282 		break;
1283 	default:
1284 		error = ENOTTY;
1285 		break;
1286 	}
1287 	return (error);
1288 }
1289 
1290 /*
1291  * vfs default ops
1292  * used to fill the vfs function table to get reasonable default return values.
1293  */
1294 int
1295 vfs_stdroot (mp, flags, vpp)
1296 	struct mount *mp;
1297 	int flags;
1298 	struct vnode **vpp;
1299 {
1300 
1301 	return (EOPNOTSUPP);
1302 }
1303 
1304 int
1305 vfs_stdstatfs (mp, sbp)
1306 	struct mount *mp;
1307 	struct statfs *sbp;
1308 {
1309 
1310 	return (EOPNOTSUPP);
1311 }
1312 
1313 int
1314 vfs_stdquotactl (mp, cmds, uid, arg)
1315 	struct mount *mp;
1316 	int cmds;
1317 	uid_t uid;
1318 	void *arg;
1319 {
1320 
1321 	return (EOPNOTSUPP);
1322 }
1323 
1324 int
1325 vfs_stdsync(mp, waitfor)
1326 	struct mount *mp;
1327 	int waitfor;
1328 {
1329 	struct vnode *vp, *mvp;
1330 	struct thread *td;
1331 	int error, lockreq, allerror = 0;
1332 
1333 	td = curthread;
1334 	lockreq = LK_EXCLUSIVE | LK_INTERLOCK;
1335 	if (waitfor != MNT_WAIT)
1336 		lockreq |= LK_NOWAIT;
1337 	/*
1338 	 * Force stale buffer cache information to be flushed.
1339 	 */
1340 loop:
1341 	MNT_VNODE_FOREACH_ALL(vp, mp, mvp) {
1342 		if (vp->v_bufobj.bo_dirty.bv_cnt == 0) {
1343 			VI_UNLOCK(vp);
1344 			continue;
1345 		}
1346 		if ((error = vget(vp, lockreq, td)) != 0) {
1347 			if (error == ENOENT) {
1348 				MNT_VNODE_FOREACH_ALL_ABORT(mp, mvp);
1349 				goto loop;
1350 			}
1351 			continue;
1352 		}
1353 		error = VOP_FSYNC(vp, waitfor, td);
1354 		if (error)
1355 			allerror = error;
1356 		vput(vp);
1357 	}
1358 	return (allerror);
1359 }
1360 
1361 int
1362 vfs_stdnosync (mp, waitfor)
1363 	struct mount *mp;
1364 	int waitfor;
1365 {
1366 
1367 	return (0);
1368 }
1369 
1370 static int
1371 vop_stdcopy_file_range(struct vop_copy_file_range_args *ap)
1372 {
1373 	int error;
1374 
1375 	error = vn_generic_copy_file_range(ap->a_invp, ap->a_inoffp,
1376 	    ap->a_outvp, ap->a_outoffp, ap->a_lenp, ap->a_flags, ap->a_incred,
1377 	    ap->a_outcred, ap->a_fsizetd);
1378 	return (error);
1379 }
1380 
1381 int
1382 vfs_stdvget (mp, ino, flags, vpp)
1383 	struct mount *mp;
1384 	ino_t ino;
1385 	int flags;
1386 	struct vnode **vpp;
1387 {
1388 
1389 	return (EOPNOTSUPP);
1390 }
1391 
1392 int
1393 vfs_stdfhtovp (mp, fhp, flags, vpp)
1394 	struct mount *mp;
1395 	struct fid *fhp;
1396 	int flags;
1397 	struct vnode **vpp;
1398 {
1399 
1400 	return (EOPNOTSUPP);
1401 }
1402 
1403 int
1404 vfs_stdinit (vfsp)
1405 	struct vfsconf *vfsp;
1406 {
1407 
1408 	return (0);
1409 }
1410 
1411 int
1412 vfs_stduninit (vfsp)
1413 	struct vfsconf *vfsp;
1414 {
1415 
1416 	return(0);
1417 }
1418 
1419 int
1420 vfs_stdextattrctl(mp, cmd, filename_vp, attrnamespace, attrname)
1421 	struct mount *mp;
1422 	int cmd;
1423 	struct vnode *filename_vp;
1424 	int attrnamespace;
1425 	const char *attrname;
1426 {
1427 
1428 	if (filename_vp != NULL)
1429 		VOP_UNLOCK(filename_vp);
1430 	return (EOPNOTSUPP);
1431 }
1432 
1433 int
1434 vfs_stdsysctl(mp, op, req)
1435 	struct mount *mp;
1436 	fsctlop_t op;
1437 	struct sysctl_req *req;
1438 {
1439 
1440 	return (EOPNOTSUPP);
1441 }
1442 
1443 static vop_bypass_t *
1444 bp_by_off(struct vop_vector *vop, struct vop_generic_args *a)
1445 {
1446 
1447 	return (*(vop_bypass_t **)((char *)vop + a->a_desc->vdesc_vop_offset));
1448 }
1449 
1450 int
1451 vop_sigdefer(struct vop_vector *vop, struct vop_generic_args *a)
1452 {
1453 	vop_bypass_t *bp;
1454 	int prev_stops, rc;
1455 
1456 	bp = bp_by_off(vop, a);
1457 	MPASS(bp != NULL);
1458 
1459 	prev_stops = sigdeferstop(SIGDEFERSTOP_SILENT);
1460 	rc = bp(a);
1461 	sigallowstop(prev_stops);
1462 	return (rc);
1463 }
1464