xref: /freebsd/sys/fs/devfs/devfs_vnops.c (revision 79ac3c12a714bcd3f2354c52d948aed9575c46d6)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3  *
4  * Copyright (c) 2000-2004
5  *	Poul-Henning Kamp.  All rights reserved.
6  * Copyright (c) 1989, 1992-1993, 1995
7  *	The Regents of the University of California.  All rights reserved.
8  *
9  * This code is derived from software donated to Berkeley by
10  * Jan-Simon Pendry.
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. 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  *	@(#)kernfs_vnops.c	8.15 (Berkeley) 5/21/95
34  * From: FreeBSD: src/sys/miscfs/kernfs/kernfs_vnops.c 1.43
35  *
36  * $FreeBSD$
37  */
38 
39 /*
40  * TODO:
41  *	mkdir: want it ?
42  */
43 
44 #include <sys/param.h>
45 #include <sys/systm.h>
46 #include <sys/conf.h>
47 #include <sys/dirent.h>
48 #include <sys/eventhandler.h>
49 #include <sys/fcntl.h>
50 #include <sys/file.h>
51 #include <sys/filedesc.h>
52 #include <sys/filio.h>
53 #include <sys/jail.h>
54 #include <sys/kernel.h>
55 #include <sys/limits.h>
56 #include <sys/lock.h>
57 #include <sys/malloc.h>
58 #include <sys/mman.h>
59 #include <sys/mount.h>
60 #include <sys/namei.h>
61 #include <sys/priv.h>
62 #include <sys/proc.h>
63 #include <sys/stat.h>
64 #include <sys/sx.h>
65 #include <sys/sysctl.h>
66 #include <sys/time.h>
67 #include <sys/ttycom.h>
68 #include <sys/unistd.h>
69 #include <sys/vnode.h>
70 
71 static struct vop_vector devfs_vnodeops;
72 static struct vop_vector devfs_specops;
73 static struct fileops devfs_ops_f;
74 
75 #include <fs/devfs/devfs.h>
76 #include <fs/devfs/devfs_int.h>
77 
78 #include <security/mac/mac_framework.h>
79 
80 #include <vm/vm.h>
81 #include <vm/vm_extern.h>
82 #include <vm/vm_object.h>
83 
84 static MALLOC_DEFINE(M_CDEVPDATA, "DEVFSP", "Metainfo for cdev-fp data");
85 
86 struct mtx	devfs_de_interlock;
87 MTX_SYSINIT(devfs_de_interlock, &devfs_de_interlock, "devfs interlock", MTX_DEF);
88 struct sx	clone_drain_lock;
89 SX_SYSINIT(clone_drain_lock, &clone_drain_lock, "clone events drain lock");
90 struct mtx	cdevpriv_mtx;
91 MTX_SYSINIT(cdevpriv_mtx, &cdevpriv_mtx, "cdevpriv lock", MTX_DEF);
92 
93 SYSCTL_DECL(_vfs_devfs);
94 
95 static int devfs_dotimes;
96 SYSCTL_INT(_vfs_devfs, OID_AUTO, dotimes, CTLFLAG_RW,
97     &devfs_dotimes, 0, "Update timestamps on DEVFS with default precision");
98 
99 /*
100  * Update devfs node timestamp.  Note that updates are unlocked and
101  * stat(2) could see partially updated times.
102  */
103 static void
104 devfs_timestamp(struct timespec *tsp)
105 {
106 	time_t ts;
107 
108 	if (devfs_dotimes) {
109 		vfs_timestamp(tsp);
110 	} else {
111 		ts = time_second;
112 		if (tsp->tv_sec != ts) {
113 			tsp->tv_sec = ts;
114 			tsp->tv_nsec = 0;
115 		}
116 	}
117 }
118 
119 static int
120 devfs_fp_check(struct file *fp, struct cdev **devp, struct cdevsw **dswp,
121     int *ref)
122 {
123 	*dswp = devvn_refthread(fp->f_vnode, devp, ref);
124 	if (*dswp == NULL || *devp != fp->f_data) {
125 		if (*dswp != NULL)
126 			dev_relthread(*devp, *ref);
127 		return (ENXIO);
128 	}
129 	KASSERT((*devp)->si_refcount > 0,
130 	    ("devfs: un-referenced struct cdev *(%s)", devtoname(*devp)));
131 	if (*dswp == NULL)
132 		return (ENXIO);
133 	curthread->td_fpop = fp;
134 	return (0);
135 }
136 
137 int
138 devfs_get_cdevpriv(void **datap)
139 {
140 	struct file *fp;
141 	struct cdev_privdata *p;
142 	int error;
143 
144 	fp = curthread->td_fpop;
145 	if (fp == NULL)
146 		return (EBADF);
147 	p = fp->f_cdevpriv;
148 	if (p != NULL) {
149 		error = 0;
150 		*datap = p->cdpd_data;
151 	} else
152 		error = ENOENT;
153 	return (error);
154 }
155 
156 int
157 devfs_set_cdevpriv(void *priv, d_priv_dtor_t *priv_dtr)
158 {
159 	struct file *fp;
160 	struct cdev_priv *cdp;
161 	struct cdev_privdata *p;
162 	int error;
163 
164 	fp = curthread->td_fpop;
165 	if (fp == NULL)
166 		return (ENOENT);
167 	cdp = cdev2priv((struct cdev *)fp->f_data);
168 	p = malloc(sizeof(struct cdev_privdata), M_CDEVPDATA, M_WAITOK);
169 	p->cdpd_data = priv;
170 	p->cdpd_dtr = priv_dtr;
171 	p->cdpd_fp = fp;
172 	mtx_lock(&cdevpriv_mtx);
173 	if (fp->f_cdevpriv == NULL) {
174 		LIST_INSERT_HEAD(&cdp->cdp_fdpriv, p, cdpd_list);
175 		fp->f_cdevpriv = p;
176 		mtx_unlock(&cdevpriv_mtx);
177 		error = 0;
178 	} else {
179 		mtx_unlock(&cdevpriv_mtx);
180 		free(p, M_CDEVPDATA);
181 		error = EBUSY;
182 	}
183 	return (error);
184 }
185 
186 void
187 devfs_destroy_cdevpriv(struct cdev_privdata *p)
188 {
189 
190 	mtx_assert(&cdevpriv_mtx, MA_OWNED);
191 	KASSERT(p->cdpd_fp->f_cdevpriv == p,
192 	    ("devfs_destoy_cdevpriv %p != %p", p->cdpd_fp->f_cdevpriv, p));
193 	p->cdpd_fp->f_cdevpriv = NULL;
194 	LIST_REMOVE(p, cdpd_list);
195 	mtx_unlock(&cdevpriv_mtx);
196 	(p->cdpd_dtr)(p->cdpd_data);
197 	free(p, M_CDEVPDATA);
198 }
199 
200 static void
201 devfs_fpdrop(struct file *fp)
202 {
203 	struct cdev_privdata *p;
204 
205 	mtx_lock(&cdevpriv_mtx);
206 	if ((p = fp->f_cdevpriv) == NULL) {
207 		mtx_unlock(&cdevpriv_mtx);
208 		return;
209 	}
210 	devfs_destroy_cdevpriv(p);
211 }
212 
213 void
214 devfs_clear_cdevpriv(void)
215 {
216 	struct file *fp;
217 
218 	fp = curthread->td_fpop;
219 	if (fp == NULL)
220 		return;
221 	devfs_fpdrop(fp);
222 }
223 
224 static void
225 devfs_usecount_add(struct vnode *vp)
226 {
227 	struct devfs_dirent *de;
228 	struct cdev *dev;
229 
230 	mtx_lock(&devfs_de_interlock);
231 	VI_LOCK(vp);
232 	VNPASS(vp->v_type == VCHR || vp->v_type == VBAD, vp);
233 	if (VN_IS_DOOMED(vp)) {
234 		goto out_unlock;
235 	}
236 
237 	de = vp->v_data;
238 	dev = vp->v_rdev;
239 	MPASS(de != NULL);
240 	MPASS(dev != NULL);
241 	dev->si_usecount++;
242 	de->de_usecount++;
243 out_unlock:
244 	VI_UNLOCK(vp);
245 	mtx_unlock(&devfs_de_interlock);
246 }
247 
248 static void
249 devfs_usecount_subl(struct vnode *vp)
250 {
251 	struct devfs_dirent *de;
252 	struct cdev *dev;
253 
254 	mtx_assert(&devfs_de_interlock, MA_OWNED);
255 	ASSERT_VI_LOCKED(vp, __func__);
256 	VNPASS(vp->v_type == VCHR || vp->v_type == VBAD, vp);
257 
258 	de = vp->v_data;
259 	dev = vp->v_rdev;
260 	if (de == NULL)
261 		return;
262 	if (dev == NULL) {
263 		MPASS(de->de_usecount == 0);
264 		return;
265 	}
266 	if (dev->si_usecount < de->de_usecount)
267 		panic("%s: si_usecount underflow for dev %p "
268 		    "(has %ld, dirent has %d)\n",
269 		    __func__, dev, dev->si_usecount, de->de_usecount);
270 	if (VN_IS_DOOMED(vp)) {
271 		dev->si_usecount -= de->de_usecount;
272 		de->de_usecount = 0;
273 	} else {
274 		if (de->de_usecount == 0)
275 			panic("%s: de_usecount underflow for dev %p\n",
276 			    __func__, dev);
277 		dev->si_usecount--;
278 		de->de_usecount--;
279 	}
280 }
281 
282 static void
283 devfs_usecount_sub(struct vnode *vp)
284 {
285 
286 	mtx_lock(&devfs_de_interlock);
287 	VI_LOCK(vp);
288 	devfs_usecount_subl(vp);
289 	VI_UNLOCK(vp);
290 	mtx_unlock(&devfs_de_interlock);
291 }
292 
293 static int
294 devfs_usecountl(struct vnode *vp)
295 {
296 
297 	VNPASS(vp->v_type == VCHR, vp);
298 	mtx_assert(&devfs_de_interlock, MA_OWNED);
299 	ASSERT_VI_LOCKED(vp, __func__);
300 	return (vp->v_rdev->si_usecount);
301 }
302 
303 int
304 devfs_usecount(struct vnode *vp)
305 {
306 	int count;
307 
308 	VNPASS(vp->v_type == VCHR, vp);
309 	mtx_lock(&devfs_de_interlock);
310 	VI_LOCK(vp);
311 	count = devfs_usecountl(vp);
312 	VI_UNLOCK(vp);
313 	mtx_unlock(&devfs_de_interlock);
314 	return (count);
315 }
316 
317 void
318 devfs_ctty_ref(struct vnode *vp)
319 {
320 
321 	vrefact(vp);
322 	devfs_usecount_add(vp);
323 }
324 
325 void
326 devfs_ctty_unref(struct vnode *vp)
327 {
328 
329 	devfs_usecount_sub(vp);
330 	vrele(vp);
331 }
332 
333 /*
334  * On success devfs_populate_vp() returns with dmp->dm_lock held.
335  */
336 static int
337 devfs_populate_vp(struct vnode *vp)
338 {
339 	struct devfs_dirent *de;
340 	struct devfs_mount *dmp;
341 	int locked;
342 
343 	ASSERT_VOP_LOCKED(vp, "devfs_populate_vp");
344 
345 	dmp = VFSTODEVFS(vp->v_mount);
346 	if (!devfs_populate_needed(dmp)) {
347 		sx_xlock(&dmp->dm_lock);
348 		goto out_nopopulate;
349 	}
350 
351 	locked = VOP_ISLOCKED(vp);
352 
353 	sx_xlock(&dmp->dm_lock);
354 	DEVFS_DMP_HOLD(dmp);
355 
356 	/* Can't call devfs_populate() with the vnode lock held. */
357 	VOP_UNLOCK(vp);
358 	devfs_populate(dmp);
359 
360 	sx_xunlock(&dmp->dm_lock);
361 	vn_lock(vp, locked | LK_RETRY);
362 	sx_xlock(&dmp->dm_lock);
363 	if (DEVFS_DMP_DROP(dmp)) {
364 		sx_xunlock(&dmp->dm_lock);
365 		devfs_unmount_final(dmp);
366 		return (ERESTART);
367 	}
368 out_nopopulate:
369 	if (VN_IS_DOOMED(vp)) {
370 		sx_xunlock(&dmp->dm_lock);
371 		return (ERESTART);
372 	}
373 	de = vp->v_data;
374 	KASSERT(de != NULL,
375 	    ("devfs_populate_vp: vp->v_data == NULL but vnode not doomed"));
376 	if ((de->de_flags & DE_DOOMED) != 0) {
377 		sx_xunlock(&dmp->dm_lock);
378 		return (ERESTART);
379 	}
380 
381 	return (0);
382 }
383 
384 static int
385 devfs_vptocnp(struct vop_vptocnp_args *ap)
386 {
387 	struct vnode *vp = ap->a_vp;
388 	struct vnode **dvp = ap->a_vpp;
389 	struct devfs_mount *dmp;
390 	char *buf = ap->a_buf;
391 	size_t *buflen = ap->a_buflen;
392 	struct devfs_dirent *dd, *de;
393 	int i, error;
394 
395 	dmp = VFSTODEVFS(vp->v_mount);
396 
397 	error = devfs_populate_vp(vp);
398 	if (error != 0)
399 		return (error);
400 
401 	if (vp->v_type != VCHR && vp->v_type != VDIR) {
402 		error = ENOENT;
403 		goto finished;
404 	}
405 
406 	dd = vp->v_data;
407 	if (vp->v_type == VDIR && dd == dmp->dm_rootdir) {
408 		*dvp = vp;
409 		vref(*dvp);
410 		goto finished;
411 	}
412 
413 	i = *buflen;
414 	i -= dd->de_dirent->d_namlen;
415 	if (i < 0) {
416 		error = ENOMEM;
417 		goto finished;
418 	}
419 	bcopy(dd->de_dirent->d_name, buf + i, dd->de_dirent->d_namlen);
420 	*buflen = i;
421 	de = devfs_parent_dirent(dd);
422 	if (de == NULL) {
423 		error = ENOENT;
424 		goto finished;
425 	}
426 	mtx_lock(&devfs_de_interlock);
427 	*dvp = de->de_vnode;
428 	if (*dvp != NULL) {
429 		VI_LOCK(*dvp);
430 		mtx_unlock(&devfs_de_interlock);
431 		vholdl(*dvp);
432 		VI_UNLOCK(*dvp);
433 		vref(*dvp);
434 		vdrop(*dvp);
435 	} else {
436 		mtx_unlock(&devfs_de_interlock);
437 		error = ENOENT;
438 	}
439 finished:
440 	sx_xunlock(&dmp->dm_lock);
441 	return (error);
442 }
443 
444 /*
445  * Construct the fully qualified path name relative to the mountpoint.
446  * If a NULL cnp is provided, no '/' is appended to the resulting path.
447  */
448 char *
449 devfs_fqpn(char *buf, struct devfs_mount *dmp, struct devfs_dirent *dd,
450     struct componentname *cnp)
451 {
452 	int i;
453 	struct devfs_dirent *de;
454 
455 	sx_assert(&dmp->dm_lock, SA_LOCKED);
456 
457 	i = SPECNAMELEN;
458 	buf[i] = '\0';
459 	if (cnp != NULL)
460 		i -= cnp->cn_namelen;
461 	if (i < 0)
462 		 return (NULL);
463 	if (cnp != NULL)
464 		bcopy(cnp->cn_nameptr, buf + i, cnp->cn_namelen);
465 	de = dd;
466 	while (de != dmp->dm_rootdir) {
467 		if (cnp != NULL || i < SPECNAMELEN) {
468 			i--;
469 			if (i < 0)
470 				 return (NULL);
471 			buf[i] = '/';
472 		}
473 		i -= de->de_dirent->d_namlen;
474 		if (i < 0)
475 			 return (NULL);
476 		bcopy(de->de_dirent->d_name, buf + i,
477 		    de->de_dirent->d_namlen);
478 		de = devfs_parent_dirent(de);
479 		if (de == NULL)
480 			return (NULL);
481 	}
482 	return (buf + i);
483 }
484 
485 static int
486 devfs_allocv_drop_refs(int drop_dm_lock, struct devfs_mount *dmp,
487 	struct devfs_dirent *de)
488 {
489 	int not_found;
490 
491 	not_found = 0;
492 	if (de->de_flags & DE_DOOMED)
493 		not_found = 1;
494 	if (DEVFS_DE_DROP(de)) {
495 		KASSERT(not_found == 1, ("DEVFS de dropped but not doomed"));
496 		devfs_dirent_free(de);
497 	}
498 	if (DEVFS_DMP_DROP(dmp)) {
499 		KASSERT(not_found == 1,
500 			("DEVFS mount struct freed before dirent"));
501 		not_found = 2;
502 		sx_xunlock(&dmp->dm_lock);
503 		devfs_unmount_final(dmp);
504 	}
505 	if (not_found == 1 || (drop_dm_lock && not_found != 2))
506 		sx_unlock(&dmp->dm_lock);
507 	return (not_found);
508 }
509 
510 static void
511 devfs_insmntque_dtr(struct vnode *vp, void *arg)
512 {
513 	struct devfs_dirent *de;
514 
515 	de = (struct devfs_dirent *)arg;
516 	mtx_lock(&devfs_de_interlock);
517 	vp->v_data = NULL;
518 	de->de_vnode = NULL;
519 	mtx_unlock(&devfs_de_interlock);
520 	vgone(vp);
521 	vput(vp);
522 }
523 
524 /*
525  * devfs_allocv shall be entered with dmp->dm_lock held, and it drops
526  * it on return.
527  */
528 int
529 devfs_allocv(struct devfs_dirent *de, struct mount *mp, int lockmode,
530     struct vnode **vpp)
531 {
532 	int error;
533 	struct vnode *vp;
534 	struct cdev *dev;
535 	struct devfs_mount *dmp;
536 	struct cdevsw *dsw;
537 	enum vgetstate vs;
538 
539 	dmp = VFSTODEVFS(mp);
540 	if (de->de_flags & DE_DOOMED) {
541 		sx_xunlock(&dmp->dm_lock);
542 		return (ENOENT);
543 	}
544 loop:
545 	DEVFS_DE_HOLD(de);
546 	DEVFS_DMP_HOLD(dmp);
547 	mtx_lock(&devfs_de_interlock);
548 	vp = de->de_vnode;
549 	if (vp != NULL) {
550 		vs = vget_prep(vp);
551 		mtx_unlock(&devfs_de_interlock);
552 		sx_xunlock(&dmp->dm_lock);
553 		vget_finish(vp, lockmode | LK_RETRY, vs);
554 		sx_xlock(&dmp->dm_lock);
555 		if (devfs_allocv_drop_refs(0, dmp, de)) {
556 			vput(vp);
557 			return (ENOENT);
558 		}
559 		else if (VN_IS_DOOMED(vp)) {
560 			mtx_lock(&devfs_de_interlock);
561 			if (de->de_vnode == vp) {
562 				de->de_vnode = NULL;
563 				vp->v_data = NULL;
564 			}
565 			mtx_unlock(&devfs_de_interlock);
566 			vput(vp);
567 			goto loop;
568 		}
569 		sx_xunlock(&dmp->dm_lock);
570 		*vpp = vp;
571 		return (0);
572 	}
573 	mtx_unlock(&devfs_de_interlock);
574 	if (de->de_dirent->d_type == DT_CHR) {
575 		if (!(de->de_cdp->cdp_flags & CDP_ACTIVE)) {
576 			devfs_allocv_drop_refs(1, dmp, de);
577 			return (ENOENT);
578 		}
579 		dev = &de->de_cdp->cdp_c;
580 	} else {
581 		dev = NULL;
582 	}
583 	error = getnewvnode("devfs", mp, &devfs_vnodeops, &vp);
584 	if (error != 0) {
585 		devfs_allocv_drop_refs(1, dmp, de);
586 		printf("devfs_allocv: failed to allocate new vnode\n");
587 		return (error);
588 	}
589 
590 	if (de->de_dirent->d_type == DT_CHR) {
591 		vp->v_type = VCHR;
592 		VI_LOCK(vp);
593 		dev_lock();
594 		dev_refl(dev);
595 		/* XXX: v_rdev should be protect by vnode lock */
596 		vp->v_rdev = dev;
597 		VNPASS(vp->v_usecount == 1, vp);
598 		/* Special casing of ttys for deadfs.  Probably redundant. */
599 		dsw = dev->si_devsw;
600 		if (dsw != NULL && (dsw->d_flags & D_TTY) != 0)
601 			vp->v_vflag |= VV_ISTTY;
602 		dev_unlock();
603 		VI_UNLOCK(vp);
604 		if ((dev->si_flags & SI_ETERNAL) != 0)
605 			vp->v_vflag |= VV_ETERNALDEV;
606 		vp->v_op = &devfs_specops;
607 	} else if (de->de_dirent->d_type == DT_DIR) {
608 		vp->v_type = VDIR;
609 	} else if (de->de_dirent->d_type == DT_LNK) {
610 		vp->v_type = VLNK;
611 	} else {
612 		vp->v_type = VBAD;
613 	}
614 	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY | LK_NOWITNESS);
615 	VN_LOCK_ASHARE(vp);
616 	mtx_lock(&devfs_de_interlock);
617 	vp->v_data = de;
618 	de->de_vnode = vp;
619 	mtx_unlock(&devfs_de_interlock);
620 	error = insmntque1(vp, mp, devfs_insmntque_dtr, de);
621 	if (error != 0) {
622 		(void) devfs_allocv_drop_refs(1, dmp, de);
623 		return (error);
624 	}
625 	if (devfs_allocv_drop_refs(0, dmp, de)) {
626 		vput(vp);
627 		return (ENOENT);
628 	}
629 #ifdef MAC
630 	mac_devfs_vnode_associate(mp, de, vp);
631 #endif
632 	sx_xunlock(&dmp->dm_lock);
633 	*vpp = vp;
634 	return (0);
635 }
636 
637 static int
638 devfs_access(struct vop_access_args *ap)
639 {
640 	struct vnode *vp = ap->a_vp;
641 	struct devfs_dirent *de;
642 	struct proc *p;
643 	int error;
644 
645 	de = vp->v_data;
646 	if (vp->v_type == VDIR)
647 		de = de->de_dir;
648 
649 	error = vaccess(vp->v_type, de->de_mode, de->de_uid, de->de_gid,
650 	    ap->a_accmode, ap->a_cred);
651 	if (error == 0)
652 		return (0);
653 	if (error != EACCES)
654 		return (error);
655 	p = ap->a_td->td_proc;
656 	/* We do, however, allow access to the controlling terminal */
657 	PROC_LOCK(p);
658 	if (!(p->p_flag & P_CONTROLT)) {
659 		PROC_UNLOCK(p);
660 		return (error);
661 	}
662 	if (p->p_session->s_ttydp == de->de_cdp)
663 		error = 0;
664 	PROC_UNLOCK(p);
665 	return (error);
666 }
667 
668 _Static_assert(((FMASK | FCNTLFLAGS) & (FLASTCLOSE | FREVOKE)) == 0,
669     "devfs-only flag reuse failed");
670 
671 static int
672 devfs_close(struct vop_close_args *ap)
673 {
674 	struct vnode *vp = ap->a_vp, *oldvp;
675 	struct thread *td = ap->a_td;
676 	struct proc *p;
677 	struct cdev *dev = vp->v_rdev;
678 	struct cdevsw *dsw;
679 	struct devfs_dirent *de = vp->v_data;
680 	int dflags, error, ref, vp_locked;
681 
682 	/*
683 	 * XXX: Don't call d_close() if we were called because of
684 	 * XXX: insmntque1() failure.
685 	 */
686 	if (vp->v_data == NULL)
687 		return (0);
688 
689 	/*
690 	 * Hack: a tty device that is a controlling terminal
691 	 * has a reference from the session structure.
692 	 * We cannot easily tell that a character device is
693 	 * a controlling terminal, unless it is the closing
694 	 * process' controlling terminal.  In that case,
695 	 * if the reference count is 2 (this last descriptor
696 	 * plus the session), release the reference from the session.
697 	 */
698 	if (de->de_usecount == 2 && td != NULL) {
699 		p = td->td_proc;
700 		PROC_LOCK(p);
701 		if (vp == p->p_session->s_ttyvp) {
702 			PROC_UNLOCK(p);
703 			oldvp = NULL;
704 			sx_xlock(&proctree_lock);
705 			if (vp == p->p_session->s_ttyvp) {
706 				SESS_LOCK(p->p_session);
707 				mtx_lock(&devfs_de_interlock);
708 				VI_LOCK(vp);
709 				if (devfs_usecountl(vp) == 2 && !VN_IS_DOOMED(vp)) {
710 					p->p_session->s_ttyvp = NULL;
711 					p->p_session->s_ttydp = NULL;
712 					oldvp = vp;
713 				}
714 				VI_UNLOCK(vp);
715 				mtx_unlock(&devfs_de_interlock);
716 				SESS_UNLOCK(p->p_session);
717 			}
718 			sx_xunlock(&proctree_lock);
719 			if (oldvp != NULL)
720 				devfs_ctty_unref(oldvp);
721 		} else
722 			PROC_UNLOCK(p);
723 	}
724 	/*
725 	 * We do not want to really close the device if it
726 	 * is still in use unless we are trying to close it
727 	 * forcibly. Since every use (buffer, vnode, swap, cmap)
728 	 * holds a reference to the vnode, and because we mark
729 	 * any other vnodes that alias this device, when the
730 	 * sum of the reference counts on all the aliased
731 	 * vnodes descends to one, we are on last close.
732 	 */
733 	dsw = dev_refthread(dev, &ref);
734 	if (dsw == NULL)
735 		return (ENXIO);
736 	dflags = 0;
737 	mtx_lock(&devfs_de_interlock);
738 	VI_LOCK(vp);
739 	if (devfs_usecountl(vp) == 1)
740 		dflags |= FLASTCLOSE;
741 	devfs_usecount_subl(vp);
742 	mtx_unlock(&devfs_de_interlock);
743 	if (VN_IS_DOOMED(vp)) {
744 		/* Forced close. */
745 		dflags |= FREVOKE | FNONBLOCK;
746 	} else if (dsw->d_flags & D_TRACKCLOSE) {
747 		/* Keep device updated on status. */
748 	} else if ((dflags & FLASTCLOSE) == 0) {
749 		VI_UNLOCK(vp);
750 		dev_relthread(dev, ref);
751 		return (0);
752 	}
753 	vholdnz(vp);
754 	VI_UNLOCK(vp);
755 	vp_locked = VOP_ISLOCKED(vp);
756 	VOP_UNLOCK(vp);
757 	KASSERT(dev->si_refcount > 0,
758 	    ("devfs_close() on un-referenced struct cdev *(%s)", devtoname(dev)));
759 	error = dsw->d_close(dev, ap->a_fflag | dflags, S_IFCHR, td);
760 	dev_relthread(dev, ref);
761 	vn_lock(vp, vp_locked | LK_RETRY);
762 	vdrop(vp);
763 	return (error);
764 }
765 
766 static int
767 devfs_close_f(struct file *fp, struct thread *td)
768 {
769 	int error;
770 	struct file *fpop;
771 
772 	/*
773 	 * NB: td may be NULL if this descriptor is closed due to
774 	 * garbage collection from a closed UNIX domain socket.
775 	 */
776 	fpop = curthread->td_fpop;
777 	curthread->td_fpop = fp;
778 	error = vnops.fo_close(fp, td);
779 	curthread->td_fpop = fpop;
780 
781 	/*
782 	 * The f_cdevpriv cannot be assigned non-NULL value while we
783 	 * are destroying the file.
784 	 */
785 	if (fp->f_cdevpriv != NULL)
786 		devfs_fpdrop(fp);
787 	return (error);
788 }
789 
790 static int
791 devfs_getattr(struct vop_getattr_args *ap)
792 {
793 	struct vnode *vp = ap->a_vp;
794 	struct vattr *vap = ap->a_vap;
795 	struct devfs_dirent *de;
796 	struct devfs_mount *dmp;
797 	struct cdev *dev;
798 	struct timeval boottime;
799 	int error;
800 
801 	error = devfs_populate_vp(vp);
802 	if (error != 0)
803 		return (error);
804 
805 	dmp = VFSTODEVFS(vp->v_mount);
806 	sx_xunlock(&dmp->dm_lock);
807 
808 	de = vp->v_data;
809 	KASSERT(de != NULL, ("Null dirent in devfs_getattr vp=%p", vp));
810 	if (vp->v_type == VDIR) {
811 		de = de->de_dir;
812 		KASSERT(de != NULL,
813 		    ("Null dir dirent in devfs_getattr vp=%p", vp));
814 	}
815 	vap->va_uid = de->de_uid;
816 	vap->va_gid = de->de_gid;
817 	vap->va_mode = de->de_mode;
818 	if (vp->v_type == VLNK)
819 		vap->va_size = strlen(de->de_symlink);
820 	else if (vp->v_type == VDIR)
821 		vap->va_size = vap->va_bytes = DEV_BSIZE;
822 	else
823 		vap->va_size = 0;
824 	if (vp->v_type != VDIR)
825 		vap->va_bytes = 0;
826 	vap->va_blocksize = DEV_BSIZE;
827 	vap->va_type = vp->v_type;
828 
829 	getboottime(&boottime);
830 #define fix(aa)							\
831 	do {							\
832 		if ((aa).tv_sec <= 3600) {			\
833 			(aa).tv_sec = boottime.tv_sec;		\
834 			(aa).tv_nsec = boottime.tv_usec * 1000; \
835 		}						\
836 	} while (0)
837 
838 	if (vp->v_type != VCHR)  {
839 		fix(de->de_atime);
840 		vap->va_atime = de->de_atime;
841 		fix(de->de_mtime);
842 		vap->va_mtime = de->de_mtime;
843 		fix(de->de_ctime);
844 		vap->va_ctime = de->de_ctime;
845 	} else {
846 		dev = vp->v_rdev;
847 		fix(dev->si_atime);
848 		vap->va_atime = dev->si_atime;
849 		fix(dev->si_mtime);
850 		vap->va_mtime = dev->si_mtime;
851 		fix(dev->si_ctime);
852 		vap->va_ctime = dev->si_ctime;
853 
854 		vap->va_rdev = cdev2priv(dev)->cdp_inode;
855 	}
856 	vap->va_gen = 0;
857 	vap->va_flags = 0;
858 	vap->va_filerev = 0;
859 	vap->va_nlink = de->de_links;
860 	vap->va_fileid = de->de_inode;
861 
862 	return (error);
863 }
864 
865 /* ARGSUSED */
866 static int
867 devfs_ioctl_f(struct file *fp, u_long com, void *data, struct ucred *cred, struct thread *td)
868 {
869 	struct file *fpop;
870 	int error;
871 
872 	fpop = td->td_fpop;
873 	td->td_fpop = fp;
874 	error = vnops.fo_ioctl(fp, com, data, cred, td);
875 	td->td_fpop = fpop;
876 	return (error);
877 }
878 
879 void *
880 fiodgname_buf_get_ptr(void *fgnp, u_long com)
881 {
882 	union {
883 		struct fiodgname_arg	fgn;
884 #ifdef COMPAT_FREEBSD32
885 		struct fiodgname_arg32	fgn32;
886 #endif
887 	} *fgnup;
888 
889 	fgnup = fgnp;
890 	switch (com) {
891 	case FIODGNAME:
892 		return (fgnup->fgn.buf);
893 #ifdef COMPAT_FREEBSD32
894 	case FIODGNAME_32:
895 		return ((void *)(uintptr_t)fgnup->fgn32.buf);
896 #endif
897 	default:
898 		panic("Unhandled ioctl command %ld", com);
899 	}
900 }
901 
902 static int
903 devfs_ioctl(struct vop_ioctl_args *ap)
904 {
905 	struct fiodgname_arg *fgn;
906 	struct vnode *vpold, *vp;
907 	struct cdevsw *dsw;
908 	struct thread *td;
909 	struct session *sess;
910 	struct cdev *dev;
911 	int error, ref, i;
912 	const char *p;
913 	u_long com;
914 
915 	vp = ap->a_vp;
916 	com = ap->a_command;
917 	td = ap->a_td;
918 
919 	dsw = devvn_refthread(vp, &dev, &ref);
920 	if (dsw == NULL)
921 		return (ENXIO);
922 	KASSERT(dev->si_refcount > 0,
923 	    ("devfs: un-referenced struct cdev *(%s)", devtoname(dev)));
924 
925 	switch (com) {
926 	case FIODTYPE:
927 		*(int *)ap->a_data = dsw->d_flags & D_TYPEMASK;
928 		error = 0;
929 		break;
930 	case FIODGNAME:
931 #ifdef	COMPAT_FREEBSD32
932 	case FIODGNAME_32:
933 #endif
934 		fgn = ap->a_data;
935 		p = devtoname(dev);
936 		i = strlen(p) + 1;
937 		if (i > fgn->len)
938 			error = EINVAL;
939 		else
940 			error = copyout(p, fiodgname_buf_get_ptr(fgn, com), i);
941 		break;
942 	default:
943 		error = dsw->d_ioctl(dev, com, ap->a_data, ap->a_fflag, td);
944 	}
945 
946 	dev_relthread(dev, ref);
947 	if (error == ENOIOCTL)
948 		error = ENOTTY;
949 
950 	if (error == 0 && com == TIOCSCTTY) {
951 		/*
952 		 * Do nothing if reassigning same control tty, or if the
953 		 * control tty has already disappeared.  If it disappeared,
954 		 * it's because we were racing with TIOCNOTTY.  TIOCNOTTY
955 		 * already took care of releasing the old vnode and we have
956 		 * nothing left to do.
957 		 */
958 		sx_slock(&proctree_lock);
959 		sess = td->td_proc->p_session;
960 		if (sess->s_ttyvp == vp || sess->s_ttyp == NULL) {
961 			sx_sunlock(&proctree_lock);
962 			return (0);
963 		}
964 
965 		devfs_ctty_ref(vp);
966 		SESS_LOCK(sess);
967 		vpold = sess->s_ttyvp;
968 		sess->s_ttyvp = vp;
969 		sess->s_ttydp = cdev2priv(dev);
970 		SESS_UNLOCK(sess);
971 
972 		sx_sunlock(&proctree_lock);
973 
974 		/* Get rid of reference to old control tty */
975 		if (vpold)
976 			devfs_ctty_unref(vpold);
977 	}
978 	return (error);
979 }
980 
981 /* ARGSUSED */
982 static int
983 devfs_kqfilter_f(struct file *fp, struct knote *kn)
984 {
985 	struct cdev *dev;
986 	struct cdevsw *dsw;
987 	int error, ref;
988 	struct file *fpop;
989 	struct thread *td;
990 
991 	td = curthread;
992 	fpop = td->td_fpop;
993 	error = devfs_fp_check(fp, &dev, &dsw, &ref);
994 	if (error)
995 		return (error);
996 	error = dsw->d_kqfilter(dev, kn);
997 	td->td_fpop = fpop;
998 	dev_relthread(dev, ref);
999 	return (error);
1000 }
1001 
1002 static inline int
1003 devfs_prison_check(struct devfs_dirent *de, struct thread *td)
1004 {
1005 	struct cdev_priv *cdp;
1006 	struct ucred *dcr;
1007 	struct proc *p;
1008 	int error;
1009 
1010 	cdp = de->de_cdp;
1011 	if (cdp == NULL)
1012 		return (0);
1013 	dcr = cdp->cdp_c.si_cred;
1014 	if (dcr == NULL)
1015 		return (0);
1016 
1017 	error = prison_check(td->td_ucred, dcr);
1018 	if (error == 0)
1019 		return (0);
1020 	/* We do, however, allow access to the controlling terminal */
1021 	p = td->td_proc;
1022 	PROC_LOCK(p);
1023 	if (!(p->p_flag & P_CONTROLT)) {
1024 		PROC_UNLOCK(p);
1025 		return (error);
1026 	}
1027 	if (p->p_session->s_ttydp == cdp)
1028 		error = 0;
1029 	PROC_UNLOCK(p);
1030 	return (error);
1031 }
1032 
1033 static int
1034 devfs_lookupx(struct vop_lookup_args *ap, int *dm_unlock)
1035 {
1036 	struct componentname *cnp;
1037 	struct vnode *dvp, **vpp;
1038 	struct thread *td;
1039 	struct devfs_dirent *de, *dd;
1040 	struct devfs_dirent **dde;
1041 	struct devfs_mount *dmp;
1042 	struct mount *mp;
1043 	struct cdev *cdev;
1044 	int error, flags, nameiop, dvplocked;
1045 	char specname[SPECNAMELEN + 1], *pname;
1046 
1047 	cnp = ap->a_cnp;
1048 	vpp = ap->a_vpp;
1049 	dvp = ap->a_dvp;
1050 	pname = cnp->cn_nameptr;
1051 	td = cnp->cn_thread;
1052 	flags = cnp->cn_flags;
1053 	nameiop = cnp->cn_nameiop;
1054 	mp = dvp->v_mount;
1055 	dmp = VFSTODEVFS(mp);
1056 	dd = dvp->v_data;
1057 	*vpp = NULLVP;
1058 
1059 	if ((flags & ISLASTCN) && nameiop == RENAME)
1060 		return (EOPNOTSUPP);
1061 
1062 	if (dvp->v_type != VDIR)
1063 		return (ENOTDIR);
1064 
1065 	if ((flags & ISDOTDOT) && (dvp->v_vflag & VV_ROOT))
1066 		return (EIO);
1067 
1068 	error = vn_dir_check_exec(dvp, cnp);
1069 	if (error != 0)
1070 		return (error);
1071 
1072 	if (cnp->cn_namelen == 1 && *pname == '.') {
1073 		if ((flags & ISLASTCN) && nameiop != LOOKUP)
1074 			return (EINVAL);
1075 		*vpp = dvp;
1076 		VREF(dvp);
1077 		return (0);
1078 	}
1079 
1080 	if (flags & ISDOTDOT) {
1081 		if ((flags & ISLASTCN) && nameiop != LOOKUP)
1082 			return (EINVAL);
1083 		de = devfs_parent_dirent(dd);
1084 		if (de == NULL)
1085 			return (ENOENT);
1086 		dvplocked = VOP_ISLOCKED(dvp);
1087 		VOP_UNLOCK(dvp);
1088 		error = devfs_allocv(de, mp, cnp->cn_lkflags & LK_TYPE_MASK,
1089 		    vpp);
1090 		*dm_unlock = 0;
1091 		vn_lock(dvp, dvplocked | LK_RETRY);
1092 		return (error);
1093 	}
1094 
1095 	dd = dvp->v_data;
1096 	de = devfs_find(dd, cnp->cn_nameptr, cnp->cn_namelen, 0);
1097 	while (de == NULL) {	/* While(...) so we can use break */
1098 
1099 		if (nameiop == DELETE)
1100 			return (ENOENT);
1101 
1102 		/*
1103 		 * OK, we didn't have an entry for the name we were asked for
1104 		 * so we try to see if anybody can create it on demand.
1105 		 */
1106 		pname = devfs_fqpn(specname, dmp, dd, cnp);
1107 		if (pname == NULL)
1108 			break;
1109 
1110 		cdev = NULL;
1111 		DEVFS_DMP_HOLD(dmp);
1112 		sx_xunlock(&dmp->dm_lock);
1113 		sx_slock(&clone_drain_lock);
1114 		EVENTHANDLER_INVOKE(dev_clone,
1115 		    td->td_ucred, pname, strlen(pname), &cdev);
1116 		sx_sunlock(&clone_drain_lock);
1117 
1118 		if (cdev == NULL)
1119 			sx_xlock(&dmp->dm_lock);
1120 		else if (devfs_populate_vp(dvp) != 0) {
1121 			*dm_unlock = 0;
1122 			sx_xlock(&dmp->dm_lock);
1123 			if (DEVFS_DMP_DROP(dmp)) {
1124 				sx_xunlock(&dmp->dm_lock);
1125 				devfs_unmount_final(dmp);
1126 			} else
1127 				sx_xunlock(&dmp->dm_lock);
1128 			dev_rel(cdev);
1129 			return (ENOENT);
1130 		}
1131 		if (DEVFS_DMP_DROP(dmp)) {
1132 			*dm_unlock = 0;
1133 			sx_xunlock(&dmp->dm_lock);
1134 			devfs_unmount_final(dmp);
1135 			if (cdev != NULL)
1136 				dev_rel(cdev);
1137 			return (ENOENT);
1138 		}
1139 
1140 		if (cdev == NULL)
1141 			break;
1142 
1143 		dev_lock();
1144 		dde = &cdev2priv(cdev)->cdp_dirents[dmp->dm_idx];
1145 		if (dde != NULL && *dde != NULL)
1146 			de = *dde;
1147 		dev_unlock();
1148 		dev_rel(cdev);
1149 		break;
1150 	}
1151 
1152 	if (de == NULL || de->de_flags & DE_WHITEOUT) {
1153 		if ((nameiop == CREATE || nameiop == RENAME) &&
1154 		    (flags & (LOCKPARENT | WANTPARENT)) && (flags & ISLASTCN)) {
1155 			cnp->cn_flags |= SAVENAME;
1156 			return (EJUSTRETURN);
1157 		}
1158 		return (ENOENT);
1159 	}
1160 
1161 	if (devfs_prison_check(de, td))
1162 		return (ENOENT);
1163 
1164 	if ((cnp->cn_nameiop == DELETE) && (flags & ISLASTCN)) {
1165 		error = VOP_ACCESS(dvp, VWRITE, cnp->cn_cred, td);
1166 		if (error)
1167 			return (error);
1168 		if (*vpp == dvp) {
1169 			VREF(dvp);
1170 			*vpp = dvp;
1171 			return (0);
1172 		}
1173 	}
1174 	error = devfs_allocv(de, mp, cnp->cn_lkflags & LK_TYPE_MASK, vpp);
1175 	*dm_unlock = 0;
1176 	return (error);
1177 }
1178 
1179 static int
1180 devfs_lookup(struct vop_lookup_args *ap)
1181 {
1182 	int j;
1183 	struct devfs_mount *dmp;
1184 	int dm_unlock;
1185 
1186 	if (devfs_populate_vp(ap->a_dvp) != 0)
1187 		return (ENOTDIR);
1188 
1189 	dmp = VFSTODEVFS(ap->a_dvp->v_mount);
1190 	dm_unlock = 1;
1191 	j = devfs_lookupx(ap, &dm_unlock);
1192 	if (dm_unlock == 1)
1193 		sx_xunlock(&dmp->dm_lock);
1194 	return (j);
1195 }
1196 
1197 static int
1198 devfs_mknod(struct vop_mknod_args *ap)
1199 {
1200 	struct componentname *cnp;
1201 	struct vnode *dvp, **vpp;
1202 	struct devfs_dirent *dd, *de;
1203 	struct devfs_mount *dmp;
1204 	int error;
1205 
1206 	/*
1207 	 * The only type of node we should be creating here is a
1208 	 * character device, for anything else return EOPNOTSUPP.
1209 	 */
1210 	if (ap->a_vap->va_type != VCHR)
1211 		return (EOPNOTSUPP);
1212 	dvp = ap->a_dvp;
1213 	dmp = VFSTODEVFS(dvp->v_mount);
1214 
1215 	cnp = ap->a_cnp;
1216 	vpp = ap->a_vpp;
1217 	dd = dvp->v_data;
1218 
1219 	error = ENOENT;
1220 	sx_xlock(&dmp->dm_lock);
1221 	TAILQ_FOREACH(de, &dd->de_dlist, de_list) {
1222 		if (cnp->cn_namelen != de->de_dirent->d_namlen)
1223 			continue;
1224 		if (de->de_dirent->d_type == DT_CHR &&
1225 		    (de->de_cdp->cdp_flags & CDP_ACTIVE) == 0)
1226 			continue;
1227 		if (bcmp(cnp->cn_nameptr, de->de_dirent->d_name,
1228 		    de->de_dirent->d_namlen) != 0)
1229 			continue;
1230 		if (de->de_flags & DE_WHITEOUT)
1231 			break;
1232 		goto notfound;
1233 	}
1234 	if (de == NULL)
1235 		goto notfound;
1236 	de->de_flags &= ~DE_WHITEOUT;
1237 	error = devfs_allocv(de, dvp->v_mount, LK_EXCLUSIVE, vpp);
1238 	return (error);
1239 notfound:
1240 	sx_xunlock(&dmp->dm_lock);
1241 	return (error);
1242 }
1243 
1244 /* ARGSUSED */
1245 static int
1246 devfs_open(struct vop_open_args *ap)
1247 {
1248 	struct thread *td = ap->a_td;
1249 	struct vnode *vp = ap->a_vp;
1250 	struct cdev *dev = vp->v_rdev;
1251 	struct file *fp = ap->a_fp;
1252 	int error, ref, vlocked;
1253 	struct cdevsw *dsw;
1254 	struct file *fpop;
1255 
1256 	if (vp->v_type == VBLK)
1257 		return (ENXIO);
1258 
1259 	if (dev == NULL)
1260 		return (ENXIO);
1261 
1262 	/* Make this field valid before any I/O in d_open. */
1263 	if (dev->si_iosize_max == 0)
1264 		dev->si_iosize_max = DFLTPHYS;
1265 
1266 	dsw = dev_refthread(dev, &ref);
1267 	if (dsw == NULL)
1268 		return (ENXIO);
1269 	if (fp == NULL && dsw->d_fdopen != NULL) {
1270 		dev_relthread(dev, ref);
1271 		return (ENXIO);
1272 	}
1273 
1274 	if (vp->v_type == VCHR)
1275 		devfs_usecount_add(vp);
1276 
1277 	vlocked = VOP_ISLOCKED(vp);
1278 	VOP_UNLOCK(vp);
1279 
1280 	fpop = td->td_fpop;
1281 	td->td_fpop = fp;
1282 	if (fp != NULL) {
1283 		fp->f_data = dev;
1284 		fp->f_vnode = vp;
1285 	}
1286 	if (dsw->d_fdopen != NULL)
1287 		error = dsw->d_fdopen(dev, ap->a_mode, td, fp);
1288 	else
1289 		error = dsw->d_open(dev, ap->a_mode, S_IFCHR, td);
1290 	/* Clean up any cdevpriv upon error. */
1291 	if (error != 0)
1292 		devfs_clear_cdevpriv();
1293 	td->td_fpop = fpop;
1294 
1295 	vn_lock(vp, vlocked | LK_RETRY);
1296 	if (error != 0 && vp->v_type == VCHR)
1297 		devfs_usecount_sub(vp);
1298 
1299 	dev_relthread(dev, ref);
1300 	if (error != 0) {
1301 		if (error == ERESTART)
1302 			error = EINTR;
1303 		return (error);
1304 	}
1305 
1306 #if 0	/* /dev/console */
1307 	KASSERT(fp != NULL, ("Could not vnode bypass device on NULL fp"));
1308 #else
1309 	if (fp == NULL)
1310 		return (error);
1311 #endif
1312 	if (fp->f_ops == &badfileops)
1313 		finit(fp, fp->f_flag, DTYPE_VNODE, dev, &devfs_ops_f);
1314 	return (error);
1315 }
1316 
1317 static int
1318 devfs_pathconf(struct vop_pathconf_args *ap)
1319 {
1320 
1321 	switch (ap->a_name) {
1322 	case _PC_FILESIZEBITS:
1323 		*ap->a_retval = 64;
1324 		return (0);
1325 	case _PC_NAME_MAX:
1326 		*ap->a_retval = NAME_MAX;
1327 		return (0);
1328 	case _PC_LINK_MAX:
1329 		*ap->a_retval = INT_MAX;
1330 		return (0);
1331 	case _PC_SYMLINK_MAX:
1332 		*ap->a_retval = MAXPATHLEN;
1333 		return (0);
1334 	case _PC_MAX_CANON:
1335 		if (ap->a_vp->v_vflag & VV_ISTTY) {
1336 			*ap->a_retval = MAX_CANON;
1337 			return (0);
1338 		}
1339 		return (EINVAL);
1340 	case _PC_MAX_INPUT:
1341 		if (ap->a_vp->v_vflag & VV_ISTTY) {
1342 			*ap->a_retval = MAX_INPUT;
1343 			return (0);
1344 		}
1345 		return (EINVAL);
1346 	case _PC_VDISABLE:
1347 		if (ap->a_vp->v_vflag & VV_ISTTY) {
1348 			*ap->a_retval = _POSIX_VDISABLE;
1349 			return (0);
1350 		}
1351 		return (EINVAL);
1352 	case _PC_MAC_PRESENT:
1353 #ifdef MAC
1354 		/*
1355 		 * If MAC is enabled, devfs automatically supports
1356 		 * trivial non-persistant label storage.
1357 		 */
1358 		*ap->a_retval = 1;
1359 #else
1360 		*ap->a_retval = 0;
1361 #endif
1362 		return (0);
1363 	case _PC_CHOWN_RESTRICTED:
1364 		*ap->a_retval = 1;
1365 		return (0);
1366 	default:
1367 		return (vop_stdpathconf(ap));
1368 	}
1369 	/* NOTREACHED */
1370 }
1371 
1372 /* ARGSUSED */
1373 static int
1374 devfs_poll_f(struct file *fp, int events, struct ucred *cred, struct thread *td)
1375 {
1376 	struct cdev *dev;
1377 	struct cdevsw *dsw;
1378 	int error, ref;
1379 	struct file *fpop;
1380 
1381 	fpop = td->td_fpop;
1382 	error = devfs_fp_check(fp, &dev, &dsw, &ref);
1383 	if (error != 0) {
1384 		error = vnops.fo_poll(fp, events, cred, td);
1385 		return (error);
1386 	}
1387 	error = dsw->d_poll(dev, events, td);
1388 	td->td_fpop = fpop;
1389 	dev_relthread(dev, ref);
1390 	return(error);
1391 }
1392 
1393 /*
1394  * Print out the contents of a special device vnode.
1395  */
1396 static int
1397 devfs_print(struct vop_print_args *ap)
1398 {
1399 
1400 	printf("\tdev %s\n", devtoname(ap->a_vp->v_rdev));
1401 	return (0);
1402 }
1403 
1404 static int
1405 devfs_read_f(struct file *fp, struct uio *uio, struct ucred *cred,
1406     int flags, struct thread *td)
1407 {
1408 	struct cdev *dev;
1409 	int ioflag, error, ref;
1410 	ssize_t resid;
1411 	struct cdevsw *dsw;
1412 	struct file *fpop;
1413 
1414 	if (uio->uio_resid > DEVFS_IOSIZE_MAX)
1415 		return (EINVAL);
1416 	fpop = td->td_fpop;
1417 	error = devfs_fp_check(fp, &dev, &dsw, &ref);
1418 	if (error != 0) {
1419 		error = vnops.fo_read(fp, uio, cred, flags, td);
1420 		return (error);
1421 	}
1422 	resid = uio->uio_resid;
1423 	ioflag = fp->f_flag & (O_NONBLOCK | O_DIRECT);
1424 	if (ioflag & O_DIRECT)
1425 		ioflag |= IO_DIRECT;
1426 
1427 	foffset_lock_uio(fp, uio, flags | FOF_NOLOCK);
1428 	error = dsw->d_read(dev, uio, ioflag);
1429 	if (uio->uio_resid != resid || (error == 0 && resid != 0))
1430 		devfs_timestamp(&dev->si_atime);
1431 	td->td_fpop = fpop;
1432 	dev_relthread(dev, ref);
1433 
1434 	foffset_unlock_uio(fp, uio, flags | FOF_NOLOCK | FOF_NEXTOFF_R);
1435 	return (error);
1436 }
1437 
1438 static int
1439 devfs_readdir(struct vop_readdir_args *ap)
1440 {
1441 	int error;
1442 	struct uio *uio;
1443 	struct dirent *dp;
1444 	struct devfs_dirent *dd;
1445 	struct devfs_dirent *de;
1446 	struct devfs_mount *dmp;
1447 	off_t off;
1448 	int *tmp_ncookies = NULL;
1449 
1450 	if (ap->a_vp->v_type != VDIR)
1451 		return (ENOTDIR);
1452 
1453 	uio = ap->a_uio;
1454 	if (uio->uio_offset < 0)
1455 		return (EINVAL);
1456 
1457 	/*
1458 	 * XXX: This is a temporary hack to get around this filesystem not
1459 	 * supporting cookies. We store the location of the ncookies pointer
1460 	 * in a temporary variable before calling vfs_subr.c:vfs_read_dirent()
1461 	 * and set the number of cookies to 0. We then set the pointer to
1462 	 * NULL so that vfs_read_dirent doesn't try to call realloc() on
1463 	 * ap->a_cookies. Later in this function, we restore the ap->a_ncookies
1464 	 * pointer to its original location before returning to the caller.
1465 	 */
1466 	if (ap->a_ncookies != NULL) {
1467 		tmp_ncookies = ap->a_ncookies;
1468 		*ap->a_ncookies = 0;
1469 		ap->a_ncookies = NULL;
1470 	}
1471 
1472 	dmp = VFSTODEVFS(ap->a_vp->v_mount);
1473 	if (devfs_populate_vp(ap->a_vp) != 0) {
1474 		if (tmp_ncookies != NULL)
1475 			ap->a_ncookies = tmp_ncookies;
1476 		return (EIO);
1477 	}
1478 	error = 0;
1479 	de = ap->a_vp->v_data;
1480 	off = 0;
1481 	TAILQ_FOREACH(dd, &de->de_dlist, de_list) {
1482 		KASSERT(dd->de_cdp != (void *)0xdeadc0de, ("%s %d\n", __func__, __LINE__));
1483 		if (dd->de_flags & (DE_COVERED | DE_WHITEOUT))
1484 			continue;
1485 		if (devfs_prison_check(dd, uio->uio_td))
1486 			continue;
1487 		if (dd->de_dirent->d_type == DT_DIR)
1488 			de = dd->de_dir;
1489 		else
1490 			de = dd;
1491 		dp = dd->de_dirent;
1492 		MPASS(dp->d_reclen == GENERIC_DIRSIZ(dp));
1493 		if (dp->d_reclen > uio->uio_resid)
1494 			break;
1495 		dp->d_fileno = de->de_inode;
1496 		/* NOTE: d_off is the offset for the *next* entry. */
1497 		dp->d_off = off + dp->d_reclen;
1498 		if (off >= uio->uio_offset) {
1499 			error = vfs_read_dirent(ap, dp, off);
1500 			if (error)
1501 				break;
1502 		}
1503 		off += dp->d_reclen;
1504 	}
1505 	sx_xunlock(&dmp->dm_lock);
1506 	uio->uio_offset = off;
1507 
1508 	/*
1509 	 * Restore ap->a_ncookies if it wasn't originally NULL in the first
1510 	 * place.
1511 	 */
1512 	if (tmp_ncookies != NULL)
1513 		ap->a_ncookies = tmp_ncookies;
1514 
1515 	return (error);
1516 }
1517 
1518 static int
1519 devfs_readlink(struct vop_readlink_args *ap)
1520 {
1521 	struct devfs_dirent *de;
1522 
1523 	de = ap->a_vp->v_data;
1524 	return (uiomove(de->de_symlink, strlen(de->de_symlink), ap->a_uio));
1525 }
1526 
1527 static void
1528 devfs_reclaiml(struct vnode *vp)
1529 {
1530 	struct devfs_dirent *de;
1531 
1532 	mtx_assert(&devfs_de_interlock, MA_OWNED);
1533 	de = vp->v_data;
1534 	if (de != NULL) {
1535 		MPASS(de->de_usecount == 0);
1536 		de->de_vnode = NULL;
1537 		vp->v_data = NULL;
1538 	}
1539 }
1540 
1541 static int
1542 devfs_reclaim(struct vop_reclaim_args *ap)
1543 {
1544 	struct vnode *vp;
1545 
1546 	vp = ap->a_vp;
1547 	mtx_lock(&devfs_de_interlock);
1548 	devfs_reclaiml(vp);
1549 	mtx_unlock(&devfs_de_interlock);
1550 	return (0);
1551 }
1552 
1553 static int
1554 devfs_reclaim_vchr(struct vop_reclaim_args *ap)
1555 {
1556 	struct vnode *vp;
1557 	struct cdev *dev;
1558 
1559 	vp = ap->a_vp;
1560 	MPASS(vp->v_type == VCHR);
1561 
1562 	mtx_lock(&devfs_de_interlock);
1563 	VI_LOCK(vp);
1564 	devfs_usecount_subl(vp);
1565 	devfs_reclaiml(vp);
1566 	mtx_unlock(&devfs_de_interlock);
1567 	dev_lock();
1568 	dev = vp->v_rdev;
1569 	vp->v_rdev = NULL;
1570 	dev_unlock();
1571 	VI_UNLOCK(vp);
1572 	if (dev != NULL)
1573 		dev_rel(dev);
1574 	return (0);
1575 }
1576 
1577 static int
1578 devfs_remove(struct vop_remove_args *ap)
1579 {
1580 	struct vnode *dvp = ap->a_dvp;
1581 	struct vnode *vp = ap->a_vp;
1582 	struct devfs_dirent *dd;
1583 	struct devfs_dirent *de, *de_covered;
1584 	struct devfs_mount *dmp = VFSTODEVFS(vp->v_mount);
1585 
1586 	ASSERT_VOP_ELOCKED(dvp, "devfs_remove");
1587 	ASSERT_VOP_ELOCKED(vp, "devfs_remove");
1588 
1589 	sx_xlock(&dmp->dm_lock);
1590 	dd = ap->a_dvp->v_data;
1591 	de = vp->v_data;
1592 	if (de->de_cdp == NULL) {
1593 		TAILQ_REMOVE(&dd->de_dlist, de, de_list);
1594 		if (de->de_dirent->d_type == DT_LNK) {
1595 			de_covered = devfs_find(dd, de->de_dirent->d_name,
1596 			    de->de_dirent->d_namlen, 0);
1597 			if (de_covered != NULL)
1598 				de_covered->de_flags &= ~DE_COVERED;
1599 		}
1600 		/* We need to unlock dvp because devfs_delete() may lock it. */
1601 		VOP_UNLOCK(vp);
1602 		if (dvp != vp)
1603 			VOP_UNLOCK(dvp);
1604 		devfs_delete(dmp, de, 0);
1605 		sx_xunlock(&dmp->dm_lock);
1606 		if (dvp != vp)
1607 			vn_lock(dvp, LK_EXCLUSIVE | LK_RETRY);
1608 		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
1609 	} else {
1610 		de->de_flags |= DE_WHITEOUT;
1611 		sx_xunlock(&dmp->dm_lock);
1612 	}
1613 	return (0);
1614 }
1615 
1616 /*
1617  * Revoke is called on a tty when a terminal session ends.  The vnode
1618  * is orphaned by setting v_op to deadfs so we need to let go of it
1619  * as well so that we create a new one next time around.
1620  *
1621  */
1622 static int
1623 devfs_revoke(struct vop_revoke_args *ap)
1624 {
1625 	struct vnode *vp = ap->a_vp, *vp2;
1626 	struct cdev *dev;
1627 	struct cdev_priv *cdp;
1628 	struct devfs_dirent *de;
1629 	enum vgetstate vs;
1630 	u_int i;
1631 
1632 	KASSERT((ap->a_flags & REVOKEALL) != 0, ("devfs_revoke !REVOKEALL"));
1633 
1634 	dev = vp->v_rdev;
1635 	cdp = cdev2priv(dev);
1636 
1637 	dev_lock();
1638 	cdp->cdp_inuse++;
1639 	dev_unlock();
1640 
1641 	vhold(vp);
1642 	vgone(vp);
1643 	vdrop(vp);
1644 
1645 	VOP_UNLOCK(vp);
1646  loop:
1647 	for (;;) {
1648 		mtx_lock(&devfs_de_interlock);
1649 		dev_lock();
1650 		vp2 = NULL;
1651 		for (i = 0; i <= cdp->cdp_maxdirent; i++) {
1652 			de = cdp->cdp_dirents[i];
1653 			if (de == NULL)
1654 				continue;
1655 
1656 			vp2 = de->de_vnode;
1657 			if (vp2 != NULL) {
1658 				dev_unlock();
1659 				vs = vget_prep(vp2);
1660 				mtx_unlock(&devfs_de_interlock);
1661 				if (vget_finish(vp2, LK_EXCLUSIVE, vs) != 0)
1662 					goto loop;
1663 				vhold(vp2);
1664 				vgone(vp2);
1665 				vdrop(vp2);
1666 				vput(vp2);
1667 				break;
1668 			}
1669 		}
1670 		if (vp2 != NULL) {
1671 			continue;
1672 		}
1673 		dev_unlock();
1674 		mtx_unlock(&devfs_de_interlock);
1675 		break;
1676 	}
1677 	dev_lock();
1678 	cdp->cdp_inuse--;
1679 	if (!(cdp->cdp_flags & CDP_ACTIVE) && cdp->cdp_inuse == 0) {
1680 		TAILQ_REMOVE(&cdevp_list, cdp, cdp_list);
1681 		dev_unlock();
1682 		dev_rel(&cdp->cdp_c);
1683 	} else
1684 		dev_unlock();
1685 
1686 	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
1687 	return (0);
1688 }
1689 
1690 static int
1691 devfs_rioctl(struct vop_ioctl_args *ap)
1692 {
1693 	struct vnode *vp;
1694 	struct devfs_mount *dmp;
1695 	int error;
1696 
1697 	vp = ap->a_vp;
1698 	vn_lock(vp, LK_SHARED | LK_RETRY);
1699 	if (VN_IS_DOOMED(vp)) {
1700 		VOP_UNLOCK(vp);
1701 		return (EBADF);
1702 	}
1703 	dmp = VFSTODEVFS(vp->v_mount);
1704 	sx_xlock(&dmp->dm_lock);
1705 	VOP_UNLOCK(vp);
1706 	DEVFS_DMP_HOLD(dmp);
1707 	devfs_populate(dmp);
1708 	if (DEVFS_DMP_DROP(dmp)) {
1709 		sx_xunlock(&dmp->dm_lock);
1710 		devfs_unmount_final(dmp);
1711 		return (ENOENT);
1712 	}
1713 	error = devfs_rules_ioctl(dmp, ap->a_command, ap->a_data, ap->a_td);
1714 	sx_xunlock(&dmp->dm_lock);
1715 	return (error);
1716 }
1717 
1718 static int
1719 devfs_rread(struct vop_read_args *ap)
1720 {
1721 
1722 	if (ap->a_vp->v_type != VDIR)
1723 		return (EINVAL);
1724 	return (VOP_READDIR(ap->a_vp, ap->a_uio, ap->a_cred, NULL, NULL, NULL));
1725 }
1726 
1727 static int
1728 devfs_setattr(struct vop_setattr_args *ap)
1729 {
1730 	struct devfs_dirent *de;
1731 	struct vattr *vap;
1732 	struct vnode *vp;
1733 	struct thread *td;
1734 	int c, error;
1735 	uid_t uid;
1736 	gid_t gid;
1737 
1738 	vap = ap->a_vap;
1739 	vp = ap->a_vp;
1740 	td = curthread;
1741 	if ((vap->va_type != VNON) ||
1742 	    (vap->va_nlink != VNOVAL) ||
1743 	    (vap->va_fsid != VNOVAL) ||
1744 	    (vap->va_fileid != VNOVAL) ||
1745 	    (vap->va_blocksize != VNOVAL) ||
1746 	    (vap->va_flags != VNOVAL && vap->va_flags != 0) ||
1747 	    (vap->va_rdev != VNOVAL) ||
1748 	    ((int)vap->va_bytes != VNOVAL) ||
1749 	    (vap->va_gen != VNOVAL)) {
1750 		return (EINVAL);
1751 	}
1752 
1753 	error = devfs_populate_vp(vp);
1754 	if (error != 0)
1755 		return (error);
1756 
1757 	de = vp->v_data;
1758 	if (vp->v_type == VDIR)
1759 		de = de->de_dir;
1760 
1761 	c = 0;
1762 	if (vap->va_uid == (uid_t)VNOVAL)
1763 		uid = de->de_uid;
1764 	else
1765 		uid = vap->va_uid;
1766 	if (vap->va_gid == (gid_t)VNOVAL)
1767 		gid = de->de_gid;
1768 	else
1769 		gid = vap->va_gid;
1770 	if (uid != de->de_uid || gid != de->de_gid) {
1771 		if ((ap->a_cred->cr_uid != de->de_uid) || uid != de->de_uid ||
1772 		    (gid != de->de_gid && !groupmember(gid, ap->a_cred))) {
1773 			error = priv_check(td, PRIV_VFS_CHOWN);
1774 			if (error != 0)
1775 				goto ret;
1776 		}
1777 		de->de_uid = uid;
1778 		de->de_gid = gid;
1779 		c = 1;
1780 	}
1781 
1782 	if (vap->va_mode != (mode_t)VNOVAL) {
1783 		if (ap->a_cred->cr_uid != de->de_uid) {
1784 			error = priv_check(td, PRIV_VFS_ADMIN);
1785 			if (error != 0)
1786 				goto ret;
1787 		}
1788 		de->de_mode = vap->va_mode;
1789 		c = 1;
1790 	}
1791 
1792 	if (vap->va_atime.tv_sec != VNOVAL || vap->va_mtime.tv_sec != VNOVAL) {
1793 		error = vn_utimes_perm(vp, vap, ap->a_cred, td);
1794 		if (error != 0)
1795 			goto ret;
1796 		if (vap->va_atime.tv_sec != VNOVAL) {
1797 			if (vp->v_type == VCHR)
1798 				vp->v_rdev->si_atime = vap->va_atime;
1799 			else
1800 				de->de_atime = vap->va_atime;
1801 		}
1802 		if (vap->va_mtime.tv_sec != VNOVAL) {
1803 			if (vp->v_type == VCHR)
1804 				vp->v_rdev->si_mtime = vap->va_mtime;
1805 			else
1806 				de->de_mtime = vap->va_mtime;
1807 		}
1808 		c = 1;
1809 	}
1810 
1811 	if (c) {
1812 		if (vp->v_type == VCHR)
1813 			vfs_timestamp(&vp->v_rdev->si_ctime);
1814 		else
1815 			vfs_timestamp(&de->de_mtime);
1816 	}
1817 
1818 ret:
1819 	sx_xunlock(&VFSTODEVFS(vp->v_mount)->dm_lock);
1820 	return (error);
1821 }
1822 
1823 #ifdef MAC
1824 static int
1825 devfs_setlabel(struct vop_setlabel_args *ap)
1826 {
1827 	struct vnode *vp;
1828 	struct devfs_dirent *de;
1829 
1830 	vp = ap->a_vp;
1831 	de = vp->v_data;
1832 
1833 	mac_vnode_relabel(ap->a_cred, vp, ap->a_label);
1834 	mac_devfs_update(vp->v_mount, de, vp);
1835 
1836 	return (0);
1837 }
1838 #endif
1839 
1840 static int
1841 devfs_stat_f(struct file *fp, struct stat *sb, struct ucred *cred, struct thread *td)
1842 {
1843 
1844 	return (vnops.fo_stat(fp, sb, cred, td));
1845 }
1846 
1847 static int
1848 devfs_symlink(struct vop_symlink_args *ap)
1849 {
1850 	int i, error;
1851 	struct devfs_dirent *dd;
1852 	struct devfs_dirent *de, *de_covered, *de_dotdot;
1853 	struct devfs_mount *dmp;
1854 
1855 	error = priv_check(curthread, PRIV_DEVFS_SYMLINK);
1856 	if (error)
1857 		return(error);
1858 	dmp = VFSTODEVFS(ap->a_dvp->v_mount);
1859 	if (devfs_populate_vp(ap->a_dvp) != 0)
1860 		return (ENOENT);
1861 
1862 	dd = ap->a_dvp->v_data;
1863 	de = devfs_newdirent(ap->a_cnp->cn_nameptr, ap->a_cnp->cn_namelen);
1864 	de->de_flags = DE_USER;
1865 	de->de_uid = 0;
1866 	de->de_gid = 0;
1867 	de->de_mode = 0755;
1868 	de->de_inode = alloc_unr(devfs_inos);
1869 	de->de_dir = dd;
1870 	de->de_dirent->d_type = DT_LNK;
1871 	i = strlen(ap->a_target) + 1;
1872 	de->de_symlink = malloc(i, M_DEVFS, M_WAITOK);
1873 	bcopy(ap->a_target, de->de_symlink, i);
1874 #ifdef MAC
1875 	mac_devfs_create_symlink(ap->a_cnp->cn_cred, dmp->dm_mount, dd, de);
1876 #endif
1877 	de_covered = devfs_find(dd, de->de_dirent->d_name,
1878 	    de->de_dirent->d_namlen, 0);
1879 	if (de_covered != NULL) {
1880 		if ((de_covered->de_flags & DE_USER) != 0) {
1881 			devfs_delete(dmp, de, DEVFS_DEL_NORECURSE);
1882 			sx_xunlock(&dmp->dm_lock);
1883 			return (EEXIST);
1884 		}
1885 		KASSERT((de_covered->de_flags & DE_COVERED) == 0,
1886 		    ("devfs_symlink: entry %p already covered", de_covered));
1887 		de_covered->de_flags |= DE_COVERED;
1888 	}
1889 
1890 	de_dotdot = TAILQ_FIRST(&dd->de_dlist);		/* "." */
1891 	de_dotdot = TAILQ_NEXT(de_dotdot, de_list);	/* ".." */
1892 	TAILQ_INSERT_AFTER(&dd->de_dlist, de_dotdot, de, de_list);
1893 	devfs_dir_ref_de(dmp, dd);
1894 	devfs_rules_apply(dmp, de);
1895 
1896 	return (devfs_allocv(de, ap->a_dvp->v_mount, LK_EXCLUSIVE, ap->a_vpp));
1897 }
1898 
1899 static int
1900 devfs_truncate_f(struct file *fp, off_t length, struct ucred *cred, struct thread *td)
1901 {
1902 
1903 	return (vnops.fo_truncate(fp, length, cred, td));
1904 }
1905 
1906 static int
1907 devfs_write_f(struct file *fp, struct uio *uio, struct ucred *cred,
1908     int flags, struct thread *td)
1909 {
1910 	struct cdev *dev;
1911 	int error, ioflag, ref;
1912 	ssize_t resid;
1913 	struct cdevsw *dsw;
1914 	struct file *fpop;
1915 
1916 	if (uio->uio_resid > DEVFS_IOSIZE_MAX)
1917 		return (EINVAL);
1918 	fpop = td->td_fpop;
1919 	error = devfs_fp_check(fp, &dev, &dsw, &ref);
1920 	if (error != 0) {
1921 		error = vnops.fo_write(fp, uio, cred, flags, td);
1922 		return (error);
1923 	}
1924 	KASSERT(uio->uio_td == td, ("uio_td %p is not td %p", uio->uio_td, td));
1925 	ioflag = fp->f_flag & (O_NONBLOCK | O_DIRECT | O_FSYNC);
1926 	if (ioflag & O_DIRECT)
1927 		ioflag |= IO_DIRECT;
1928 	foffset_lock_uio(fp, uio, flags | FOF_NOLOCK);
1929 
1930 	resid = uio->uio_resid;
1931 
1932 	error = dsw->d_write(dev, uio, ioflag);
1933 	if (uio->uio_resid != resid || (error == 0 && resid != 0)) {
1934 		devfs_timestamp(&dev->si_ctime);
1935 		dev->si_mtime = dev->si_ctime;
1936 	}
1937 	td->td_fpop = fpop;
1938 	dev_relthread(dev, ref);
1939 
1940 	foffset_unlock_uio(fp, uio, flags | FOF_NOLOCK | FOF_NEXTOFF_W);
1941 	return (error);
1942 }
1943 
1944 static int
1945 devfs_mmap_f(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t size,
1946     vm_prot_t prot, vm_prot_t cap_maxprot, int flags, vm_ooffset_t foff,
1947     struct thread *td)
1948 {
1949 	struct cdev *dev;
1950 	struct cdevsw *dsw;
1951 	struct mount *mp;
1952 	struct vnode *vp;
1953 	struct file *fpop;
1954 	vm_object_t object;
1955 	vm_prot_t maxprot;
1956 	int error, ref;
1957 
1958 	vp = fp->f_vnode;
1959 
1960 	/*
1961 	 * Ensure that file and memory protections are
1962 	 * compatible.
1963 	 */
1964 	mp = vp->v_mount;
1965 	if (mp != NULL && (mp->mnt_flag & MNT_NOEXEC) != 0) {
1966 		maxprot = VM_PROT_NONE;
1967 		if ((prot & VM_PROT_EXECUTE) != 0)
1968 			return (EACCES);
1969 	} else
1970 		maxprot = VM_PROT_EXECUTE;
1971 	if ((fp->f_flag & FREAD) != 0)
1972 		maxprot |= VM_PROT_READ;
1973 	else if ((prot & VM_PROT_READ) != 0)
1974 		return (EACCES);
1975 
1976 	/*
1977 	 * If we are sharing potential changes via MAP_SHARED and we
1978 	 * are trying to get write permission although we opened it
1979 	 * without asking for it, bail out.
1980 	 *
1981 	 * Note that most character devices always share mappings.
1982 	 * The one exception is that D_MMAP_ANON devices
1983 	 * (i.e. /dev/zero) permit private writable mappings.
1984 	 *
1985 	 * Rely on vm_mmap_cdev() to fail invalid MAP_PRIVATE requests
1986 	 * as well as updating maxprot to permit writing for
1987 	 * D_MMAP_ANON devices rather than doing that here.
1988 	 */
1989 	if ((flags & MAP_SHARED) != 0) {
1990 		if ((fp->f_flag & FWRITE) != 0)
1991 			maxprot |= VM_PROT_WRITE;
1992 		else if ((prot & VM_PROT_WRITE) != 0)
1993 			return (EACCES);
1994 	}
1995 	maxprot &= cap_maxprot;
1996 
1997 	fpop = td->td_fpop;
1998 	error = devfs_fp_check(fp, &dev, &dsw, &ref);
1999 	if (error != 0)
2000 		return (error);
2001 
2002 	error = vm_mmap_cdev(td, size, prot, &maxprot, &flags, dev, dsw, &foff,
2003 	    &object);
2004 	td->td_fpop = fpop;
2005 	dev_relthread(dev, ref);
2006 	if (error != 0)
2007 		return (error);
2008 
2009 	error = vm_mmap_object(map, addr, size, prot, maxprot, flags, object,
2010 	    foff, FALSE, td);
2011 	if (error != 0)
2012 		vm_object_deallocate(object);
2013 	return (error);
2014 }
2015 
2016 dev_t
2017 dev2udev(struct cdev *x)
2018 {
2019 	if (x == NULL)
2020 		return (NODEV);
2021 	return (cdev2priv(x)->cdp_inode);
2022 }
2023 
2024 static struct fileops devfs_ops_f = {
2025 	.fo_read =	devfs_read_f,
2026 	.fo_write =	devfs_write_f,
2027 	.fo_truncate =	devfs_truncate_f,
2028 	.fo_ioctl =	devfs_ioctl_f,
2029 	.fo_poll =	devfs_poll_f,
2030 	.fo_kqfilter =	devfs_kqfilter_f,
2031 	.fo_stat =	devfs_stat_f,
2032 	.fo_close =	devfs_close_f,
2033 	.fo_chmod =	vn_chmod,
2034 	.fo_chown =	vn_chown,
2035 	.fo_sendfile =	vn_sendfile,
2036 	.fo_seek =	vn_seek,
2037 	.fo_fill_kinfo = vn_fill_kinfo,
2038 	.fo_mmap =	devfs_mmap_f,
2039 	.fo_flags =	DFLAG_PASSABLE | DFLAG_SEEKABLE
2040 };
2041 
2042 /* Vops for non-CHR vnodes in /dev. */
2043 static struct vop_vector devfs_vnodeops = {
2044 	.vop_default =		&default_vnodeops,
2045 
2046 	.vop_access =		devfs_access,
2047 	.vop_getattr =		devfs_getattr,
2048 	.vop_ioctl =		devfs_rioctl,
2049 	.vop_lookup =		devfs_lookup,
2050 	.vop_mknod =		devfs_mknod,
2051 	.vop_pathconf =		devfs_pathconf,
2052 	.vop_read =		devfs_rread,
2053 	.vop_readdir =		devfs_readdir,
2054 	.vop_readlink =		devfs_readlink,
2055 	.vop_reclaim =		devfs_reclaim,
2056 	.vop_remove =		devfs_remove,
2057 	.vop_revoke =		devfs_revoke,
2058 	.vop_setattr =		devfs_setattr,
2059 #ifdef MAC
2060 	.vop_setlabel =		devfs_setlabel,
2061 #endif
2062 	.vop_symlink =		devfs_symlink,
2063 	.vop_vptocnp =		devfs_vptocnp,
2064 	.vop_lock1 =		vop_lock,
2065 	.vop_unlock =		vop_unlock,
2066 	.vop_islocked =		vop_islocked,
2067 };
2068 VFS_VOP_VECTOR_REGISTER(devfs_vnodeops);
2069 
2070 /* Vops for VCHR vnodes in /dev. */
2071 static struct vop_vector devfs_specops = {
2072 	.vop_default =		&default_vnodeops,
2073 
2074 	.vop_access =		devfs_access,
2075 	.vop_bmap =		VOP_PANIC,
2076 	.vop_close =		devfs_close,
2077 	.vop_create =		VOP_PANIC,
2078 	.vop_fsync =		vop_stdfsync,
2079 	.vop_getattr =		devfs_getattr,
2080 	.vop_ioctl =		devfs_ioctl,
2081 	.vop_link =		VOP_PANIC,
2082 	.vop_mkdir =		VOP_PANIC,
2083 	.vop_mknod =		VOP_PANIC,
2084 	.vop_open =		devfs_open,
2085 	.vop_pathconf =		devfs_pathconf,
2086 	.vop_poll =		dead_poll,
2087 	.vop_print =		devfs_print,
2088 	.vop_read =		dead_read,
2089 	.vop_readdir =		VOP_PANIC,
2090 	.vop_readlink =		VOP_PANIC,
2091 	.vop_reallocblks =	VOP_PANIC,
2092 	.vop_reclaim =		devfs_reclaim_vchr,
2093 	.vop_remove =		devfs_remove,
2094 	.vop_rename =		VOP_PANIC,
2095 	.vop_revoke =		devfs_revoke,
2096 	.vop_rmdir =		VOP_PANIC,
2097 	.vop_setattr =		devfs_setattr,
2098 #ifdef MAC
2099 	.vop_setlabel =		devfs_setlabel,
2100 #endif
2101 	.vop_strategy =		VOP_PANIC,
2102 	.vop_symlink =		VOP_PANIC,
2103 	.vop_vptocnp =		devfs_vptocnp,
2104 	.vop_write =		dead_write,
2105 	.vop_lock1 =		vop_lock,
2106 	.vop_unlock =		vop_unlock,
2107 	.vop_islocked =		vop_islocked,
2108 };
2109 VFS_VOP_VECTOR_REGISTER(devfs_specops);
2110 
2111 /*
2112  * Our calling convention to the device drivers used to be that we passed
2113  * vnode.h IO_* flags to read()/write(), but we're moving to fcntl.h O_
2114  * flags instead since that's what open(), close() and ioctl() takes and
2115  * we don't really want vnode.h in device drivers.
2116  * We solved the source compatibility by redefining some vnode flags to
2117  * be the same as the fcntl ones and by sending down the bitwise OR of
2118  * the respective fcntl/vnode flags.  These CTASSERTS make sure nobody
2119  * pulls the rug out under this.
2120  */
2121 CTASSERT(O_NONBLOCK == IO_NDELAY);
2122 CTASSERT(O_FSYNC == IO_SYNC);
2123