xref: /dflybsd-src/sys/vfs/devfs/devfs_vnops.c (revision 65c62024e97be0964ff6de261081aec59a904f78)
1 /*
2  * Copyright (c) 2009 The DragonFly Project.  All rights reserved.
3  *
4  * This code is derived from software contributed to The DragonFly Project
5  * by Alex Hornung <ahornung@gmail.com>
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  *
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in
15  *    the documentation and/or other materials provided with the
16  *    distribution.
17  * 3. Neither the name of The DragonFly Project nor the names of its
18  *    contributors may be used to endorse or promote products derived
19  *    from this software without specific, prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  */
34 #include <sys/param.h>
35 #include <sys/systm.h>
36 #include <sys/time.h>
37 #include <sys/kernel.h>
38 #include <sys/lock.h>
39 #include <sys/fcntl.h>
40 #include <sys/proc.h>
41 #include <sys/priv.h>
42 #include <sys/signalvar.h>
43 #include <sys/vnode.h>
44 #include <sys/uio.h>
45 #include <sys/mount.h>
46 #include <sys/file.h>
47 #include <sys/fcntl.h>
48 #include <sys/namei.h>
49 #include <sys/dirent.h>
50 #include <sys/malloc.h>
51 #include <sys/stat.h>
52 #include <sys/reg.h>
53 #include <vm/vm_pager.h>
54 #include <vm/vm_zone.h>
55 #include <vm/vm_object.h>
56 #include <sys/filio.h>
57 #include <sys/ttycom.h>
58 #include <sys/tty.h>
59 #include <sys/devfs.h>
60 #include <sys/pioctl.h>
61 
62 #include <machine/limits.h>
63 #include <vm/vm_page2.h>
64 #include <sys/buf2.h>
65 #include <sys/sysref2.h>
66 
67 MALLOC_DECLARE(M_DEVFS);
68 #define DEVFS_BADOP	(void *)devfs_badop
69 
70 static int devfs_badop(struct vop_generic_args *);
71 static int devfs_access(struct vop_access_args *);
72 static int devfs_inactive(struct vop_inactive_args *);
73 static int devfs_reclaim(struct vop_reclaim_args *);
74 static int devfs_readdir(struct vop_readdir_args *);
75 static int devfs_getattr(struct vop_getattr_args *);
76 static int devfs_setattr(struct vop_setattr_args *);
77 static int devfs_readlink(struct vop_readlink_args *);
78 static int devfs_print(struct vop_print_args *);
79 
80 static int devfs_nresolve(struct vop_nresolve_args *);
81 static int devfs_nlookupdotdot(struct vop_nlookupdotdot_args *);
82 static int devfs_nsymlink(struct vop_nsymlink_args *);
83 static int devfs_nremove(struct vop_nremove_args *);
84 
85 static int devfs_spec_open(struct vop_open_args *);
86 static int devfs_spec_close(struct vop_close_args *);
87 static int devfs_spec_fsync(struct vop_fsync_args *);
88 
89 static int devfs_spec_read(struct vop_read_args *);
90 static int devfs_spec_write(struct vop_write_args *);
91 static int devfs_spec_ioctl(struct vop_ioctl_args *);
92 static int devfs_spec_poll(struct vop_poll_args *);
93 static int devfs_spec_kqfilter(struct vop_kqfilter_args *);
94 static int devfs_spec_strategy(struct vop_strategy_args *);
95 static void devfs_spec_strategy_done(struct bio *);
96 static int devfs_spec_freeblks(struct vop_freeblks_args *);
97 static int devfs_spec_bmap(struct vop_bmap_args *);
98 static int devfs_spec_advlock(struct vop_advlock_args *);
99 static void devfs_spec_getpages_iodone(struct bio *);
100 static int devfs_spec_getpages(struct vop_getpages_args *);
101 
102 
103 static int devfs_specf_close(struct file *);
104 static int devfs_specf_read(struct file *, struct uio *, struct ucred *, int);
105 static int devfs_specf_write(struct file *, struct uio *, struct ucred *, int);
106 static int devfs_specf_stat(struct file *, struct stat *, struct ucred *);
107 static int devfs_specf_kqfilter(struct file *, struct knote *);
108 static int devfs_specf_poll(struct file *, int, struct ucred *);
109 static int devfs_specf_ioctl(struct file *, u_long, caddr_t,
110 				struct ucred *, struct sysmsg *);
111 static __inline int sequential_heuristic(struct uio *, struct file *);
112 
113 extern struct lock devfs_lock;
114 
115 /*
116  * devfs vnode operations for regular files
117  */
118 struct vop_ops devfs_vnode_norm_vops = {
119 	.vop_default =		vop_defaultop,
120 	.vop_access =		devfs_access,
121 	.vop_advlock =		DEVFS_BADOP,
122 	.vop_bmap =			DEVFS_BADOP,
123 	.vop_close =		vop_stdclose,
124 	.vop_getattr =		devfs_getattr,
125 	.vop_inactive =		devfs_inactive,
126 	.vop_ncreate =		DEVFS_BADOP,
127 	.vop_nresolve =		devfs_nresolve,
128 	.vop_nlookupdotdot =	devfs_nlookupdotdot,
129 	.vop_nlink =		DEVFS_BADOP,
130 	.vop_nmkdir =		DEVFS_BADOP,
131 	.vop_nmknod =		DEVFS_BADOP,
132 	.vop_nremove =		devfs_nremove,
133 	.vop_nrename =		DEVFS_BADOP,
134 	.vop_nrmdir =		DEVFS_BADOP,
135 	.vop_nsymlink =		devfs_nsymlink,
136 	.vop_open =			vop_stdopen,
137 	.vop_pathconf =		vop_stdpathconf,
138 	.vop_print =		devfs_print,
139 	.vop_read =			DEVFS_BADOP,
140 	.vop_readdir =		devfs_readdir,
141 	.vop_readlink =		devfs_readlink,
142 	.vop_reclaim =		devfs_reclaim,
143 	.vop_setattr =		devfs_setattr,
144 	.vop_write =		DEVFS_BADOP,
145 	.vop_ioctl =		DEVFS_BADOP
146 };
147 
148 /*
149  * devfs vnode operations for character devices
150  */
151 struct vop_ops devfs_vnode_dev_vops = {
152 	.vop_default =		vop_defaultop,
153 	.vop_access =		devfs_access,
154 	.vop_advlock =		devfs_spec_advlock,
155 	.vop_bmap =			devfs_spec_bmap,
156 	.vop_close =		devfs_spec_close,
157 	.vop_freeblks =		devfs_spec_freeblks,
158 	.vop_fsync =		devfs_spec_fsync,
159 	.vop_getattr =		devfs_getattr,
160 	.vop_getpages =		devfs_spec_getpages,
161 	.vop_inactive =		devfs_inactive,
162 	.vop_open =			devfs_spec_open,
163 	.vop_pathconf =		vop_stdpathconf,
164 	.vop_print =		devfs_print,
165 	.vop_poll =			devfs_spec_poll,
166 	.vop_kqfilter =		devfs_spec_kqfilter,
167 	.vop_read =			devfs_spec_read,
168 	.vop_readdir =		DEVFS_BADOP,
169 	.vop_readlink =		DEVFS_BADOP,
170 	.vop_reclaim =		devfs_reclaim,
171 	.vop_setattr =		devfs_setattr,
172 	.vop_strategy =		devfs_spec_strategy,
173 	.vop_write =		devfs_spec_write,
174 	.vop_ioctl =		devfs_spec_ioctl
175 };
176 
177 struct vop_ops *devfs_vnode_dev_vops_p = &devfs_vnode_dev_vops;
178 
179 struct fileops devfs_dev_fileops = {
180 	.fo_read = devfs_specf_read,
181 	.fo_write = devfs_specf_write,
182 	.fo_ioctl = devfs_specf_ioctl,
183 	.fo_poll = devfs_specf_poll,
184 	.fo_kqfilter = devfs_specf_kqfilter,
185 	.fo_stat = devfs_specf_stat,
186 	.fo_close = devfs_specf_close,
187 	.fo_shutdown = nofo_shutdown
188 };
189 
190 /*
191  * These two functions are possibly temporary hacks for
192  * devices (aka the pty code) which want to control the
193  * node attributes themselves.
194  *
195  * XXX we may ultimately desire to simply remove the uid/gid/mode
196  * from the node entirely.
197  */
198 static __inline void
199 node_sync_dev_get(struct devfs_node *node)
200 {
201 	cdev_t dev;
202 
203 	if ((dev = node->d_dev) && (dev->si_flags & SI_OVERRIDE)) {
204 		node->uid = dev->si_uid;
205 		node->gid = dev->si_gid;
206 		node->mode = dev->si_perms;
207 	}
208 }
209 
210 static __inline void
211 node_sync_dev_set(struct devfs_node *node)
212 {
213 	cdev_t dev;
214 
215 	if ((dev = node->d_dev) && (dev->si_flags & SI_OVERRIDE)) {
216 		dev->si_uid = node->uid;
217 		dev->si_gid = node->gid;
218 		dev->si_perms = node->mode;
219 	}
220 }
221 
222 /*
223  * generic entry point for unsupported operations
224  */
225 static int
226 devfs_badop(struct vop_generic_args *ap)
227 {
228 	return (EIO);
229 }
230 
231 
232 static int
233 devfs_access(struct vop_access_args *ap)
234 {
235 	struct devfs_node *node = DEVFS_NODE(ap->a_vp);
236 	int error;
237 
238 	if (!devfs_node_is_accessible(node))
239 		return ENOENT;
240 	node_sync_dev_get(node);
241 	error = vop_helper_access(ap, node->uid, node->gid,
242 				  node->mode, node->flags);
243 
244 	return error;
245 }
246 
247 
248 static int
249 devfs_inactive(struct vop_inactive_args *ap)
250 {
251 	struct devfs_node *node = DEVFS_NODE(ap->a_vp);
252 
253 	if (node == NULL || (node->flags & DEVFS_NODE_LINKED) == 0)
254 		vrecycle(ap->a_vp);
255 	return 0;
256 }
257 
258 
259 static int
260 devfs_reclaim(struct vop_reclaim_args *ap)
261 {
262 	struct devfs_node *node;
263 	struct vnode *vp;
264 	int locked;
265 
266 	/*
267 	 * Check if it is locked already. if not, we acquire the devfs lock
268 	 */
269 	if (!(lockstatus(&devfs_lock, curthread)) == LK_EXCLUSIVE) {
270 		lockmgr(&devfs_lock, LK_EXCLUSIVE);
271 		locked = 1;
272 	} else {
273 		locked = 0;
274 	}
275 
276 	/*
277 	 * Get rid of the devfs_node if it is no longer linked into the
278 	 * topology.
279 	 */
280 	vp = ap->a_vp;
281 	if ((node = DEVFS_NODE(vp)) != NULL) {
282 		node->v_node = NULL;
283 		if ((node->flags & DEVFS_NODE_LINKED) == 0)
284 			devfs_freep(node);
285 	}
286 
287 	if (locked)
288 		lockmgr(&devfs_lock, LK_RELEASE);
289 
290 	/*
291 	 * v_rdev needs to be properly released using v_release_rdev
292 	 * Make sure v_data is NULL as well.
293 	 */
294 	vp->v_data = NULL;
295 	v_release_rdev(vp);
296 	return 0;
297 }
298 
299 
300 static int
301 devfs_readdir(struct vop_readdir_args *ap)
302 {
303 	struct devfs_node *dnode = DEVFS_NODE(ap->a_vp);
304 	struct devfs_node *node;
305 	int cookie_index;
306 	int ncookies;
307 	int error2;
308 	int error;
309 	int r;
310 	off_t *cookies;
311 	off_t saveoff;
312 
313 	devfs_debug(DEVFS_DEBUG_DEBUG, "devfs_readdir() called!\n");
314 
315 	if (ap->a_uio->uio_offset < 0 || ap->a_uio->uio_offset > INT_MAX)
316 		return (EINVAL);
317 	if ((error = vn_lock(ap->a_vp, LK_EXCLUSIVE | LK_RETRY)) != 0)
318 		return (error);
319 
320 	if (!devfs_node_is_accessible(dnode))
321 		return ENOENT;
322 
323 	lockmgr(&devfs_lock, LK_EXCLUSIVE);
324 
325 	saveoff = ap->a_uio->uio_offset;
326 
327 	if (ap->a_ncookies) {
328 		ncookies = ap->a_uio->uio_resid / 16 + 1; /* Why / 16 ?? */
329 		if (ncookies > 256)
330 			ncookies = 256;
331 		cookies = kmalloc(256 * sizeof(off_t), M_TEMP, M_WAITOK);
332 		cookie_index = 0;
333 	} else {
334 		ncookies = -1;
335 		cookies = NULL;
336 		cookie_index = 0;
337 	}
338 
339 	nanotime(&dnode->atime);
340 
341 	if (saveoff == 0) {
342 		r = vop_write_dirent(&error, ap->a_uio, dnode->d_dir.d_ino,
343 				     DT_DIR, 1, ".");
344 		if (r)
345 			goto done;
346 		if (cookies)
347 			cookies[cookie_index] = saveoff;
348 		saveoff++;
349 		cookie_index++;
350 		if (cookie_index == ncookies)
351 			goto done;
352 	}
353 
354 	if (saveoff == 1) {
355 		if (dnode->parent) {
356 			r = vop_write_dirent(&error, ap->a_uio,
357 					     dnode->parent->d_dir.d_ino,
358 					     DT_DIR, 2, "..");
359 		} else {
360 			r = vop_write_dirent(&error, ap->a_uio,
361 					     dnode->d_dir.d_ino,
362 					     DT_DIR, 2, "..");
363 		}
364 		if (r)
365 			goto done;
366 		if (cookies)
367 			cookies[cookie_index] = saveoff;
368 		saveoff++;
369 		cookie_index++;
370 		if (cookie_index == ncookies)
371 			goto done;
372 	}
373 
374 	TAILQ_FOREACH(node, DEVFS_DENODE_HEAD(dnode), link) {
375 		if ((node->flags & DEVFS_HIDDEN) ||
376 		    (node->flags & DEVFS_INVISIBLE)) {
377 			continue;
378 		}
379 
380 		/*
381 		 * If the node type is a valid devfs alias, then we make sure that the
382 		 * target isn't hidden. If it is, we don't show the link in the
383 		 * directory listing.
384 		 */
385 		if ((node->node_type == Plink) && (node->link_target != NULL) &&
386 			(node->link_target->flags & DEVFS_HIDDEN))
387 			continue;
388 
389 		if (node->cookie < saveoff)
390 			continue;
391 
392 		saveoff = node->cookie;
393 
394 		error2 = vop_write_dirent(&error, ap->a_uio, node->d_dir.d_ino,
395 					  node->d_dir.d_type,
396 					  node->d_dir.d_namlen,
397 					  node->d_dir.d_name);
398 
399 		if (error2)
400 			break;
401 
402 		saveoff++;
403 
404 		if (cookies)
405 			cookies[cookie_index] = node->cookie;
406 		++cookie_index;
407 		if (cookie_index == ncookies)
408 			break;
409 	}
410 
411 done:
412 	lockmgr(&devfs_lock, LK_RELEASE);
413 	vn_unlock(ap->a_vp);
414 
415 	ap->a_uio->uio_offset = saveoff;
416 	if (error && cookie_index == 0) {
417 		if (cookies) {
418 			kfree(cookies, M_TEMP);
419 			*ap->a_ncookies = 0;
420 			*ap->a_cookies = NULL;
421 		}
422 	} else {
423 		if (cookies) {
424 			*ap->a_ncookies = cookie_index;
425 			*ap->a_cookies = cookies;
426 		}
427 	}
428 	return (error);
429 }
430 
431 
432 static int
433 devfs_nresolve(struct vop_nresolve_args *ap)
434 {
435 	struct devfs_node *dnode = DEVFS_NODE(ap->a_dvp);
436 	struct devfs_node *node, *found = NULL;
437 	struct namecache *ncp;
438 	struct vnode *vp = NULL;
439 	int error = 0;
440 	int len;
441 	int hidden = 0;
442 	int depth;
443 
444 	ncp = ap->a_nch->ncp;
445 	len = ncp->nc_nlen;
446 
447 	if (!devfs_node_is_accessible(dnode))
448 		return ENOENT;
449 
450 	lockmgr(&devfs_lock, LK_EXCLUSIVE);
451 
452 	if ((dnode->node_type != Proot) && (dnode->node_type != Pdir)) {
453 		error = ENOENT;
454 		cache_setvp(ap->a_nch, NULL);
455 		goto out;
456 	}
457 
458 	TAILQ_FOREACH(node, DEVFS_DENODE_HEAD(dnode), link) {
459 		if (len == node->d_dir.d_namlen) {
460 			if (!memcmp(ncp->nc_name, node->d_dir.d_name, len)) {
461 				found = node;
462 				break;
463 			}
464 		}
465 	}
466 
467 	if (found) {
468 		depth = 0;
469 		while ((found->node_type == Plink) && (found->link_target)) {
470 			if (depth >= 8) {
471 				devfs_debug(DEVFS_DEBUG_SHOW, "Recursive link or depth >= 8");
472 				break;
473 			}
474 
475 			found = found->link_target;
476 			++depth;
477 		}
478 
479 		if (!(found->flags & DEVFS_HIDDEN))
480 			devfs_allocv(/*ap->a_dvp->v_mount, */ &vp, found);
481 		else
482 			hidden = 1;
483 	}
484 
485 	if (vp == NULL) {
486 		error = ENOENT;
487 		cache_setvp(ap->a_nch, NULL);
488 		goto out;
489 
490 	}
491 	KKASSERT(vp);
492 	vn_unlock(vp);
493 	cache_setvp(ap->a_nch, vp);
494 	vrele(vp);
495 out:
496 	lockmgr(&devfs_lock, LK_RELEASE);
497 
498 	return error;
499 }
500 
501 
502 static int
503 devfs_nlookupdotdot(struct vop_nlookupdotdot_args *ap)
504 {
505 	struct devfs_node *dnode = DEVFS_NODE(ap->a_dvp);
506 
507 	*ap->a_vpp = NULL;
508 	if (!devfs_node_is_accessible(dnode))
509 		return ENOENT;
510 
511 	lockmgr(&devfs_lock, LK_EXCLUSIVE);
512 	if (dnode->parent != NULL) {
513 		devfs_allocv(ap->a_vpp, dnode->parent);
514 		vn_unlock(*ap->a_vpp);
515 	}
516 	lockmgr(&devfs_lock, LK_RELEASE);
517 
518 	return ((*ap->a_vpp == NULL) ? ENOENT : 0);
519 }
520 
521 
522 static int
523 devfs_getattr(struct vop_getattr_args *ap)
524 {
525 	struct devfs_node *node = DEVFS_NODE(ap->a_vp);
526 	struct vattr *vap = ap->a_vap;
527 	int error = 0;
528 
529 #if 0
530 	if (!devfs_node_is_accessible(node))
531 		return ENOENT;
532 #endif
533 	node_sync_dev_get(node);
534 
535 	lockmgr(&devfs_lock, LK_EXCLUSIVE);
536 
537 	/* start by zeroing out the attributes */
538 	VATTR_NULL(vap);
539 
540 	/* next do all the common fields */
541 	vap->va_type = ap->a_vp->v_type;
542 	vap->va_mode = node->mode;
543 	vap->va_fileid = DEVFS_NODE(ap->a_vp)->d_dir.d_ino ;
544 	vap->va_flags = 0; /* XXX: what should this be? */
545 	vap->va_blocksize = DEV_BSIZE;
546 	vap->va_bytes = vap->va_size = sizeof(struct devfs_node);
547 
548 	vap->va_fsid = ap->a_vp->v_mount->mnt_stat.f_fsid.val[0];
549 
550 	vap->va_atime = node->atime;
551 	vap->va_mtime = node->mtime;
552 	vap->va_ctime = node->ctime;
553 
554 	vap->va_nlink = 1; /* number of references to file */
555 
556 	vap->va_uid = node->uid;
557 	vap->va_gid = node->gid;
558 
559 	vap->va_rmajor = 0;
560 	vap->va_rminor = 0;
561 
562 	if ((node->node_type == Pdev) && node->d_dev)  {
563 		reference_dev(node->d_dev);
564 		vap->va_rminor = node->d_dev->si_uminor;
565 		release_dev(node->d_dev);
566 	}
567 
568 	/* For a softlink the va_size is the length of the softlink */
569 	if (node->symlink_name != 0) {
570 		vap->va_size = node->symlink_namelen;
571 	}
572 	lockmgr(&devfs_lock, LK_RELEASE);
573 
574 	return (error);
575 }
576 
577 
578 static int
579 devfs_setattr(struct vop_setattr_args *ap)
580 {
581 	struct devfs_node *node = DEVFS_NODE(ap->a_vp);
582 	struct vattr *vap;
583 	int error = 0;
584 
585 	if (!devfs_node_is_accessible(node))
586 		return ENOENT;
587 	node_sync_dev_get(node);
588 
589 	lockmgr(&devfs_lock, LK_EXCLUSIVE);
590 
591 	vap = ap->a_vap;
592 
593 	if (vap->va_uid != (uid_t)VNOVAL) {
594 		if ((ap->a_cred->cr_uid != node->uid) &&
595 		    (!groupmember(node->gid, ap->a_cred))) {
596 			error = priv_check(curthread, PRIV_VFS_CHOWN);
597 			if (error)
598 				goto out;
599 		}
600 		node->uid = vap->va_uid;
601 	}
602 
603 	if (vap->va_gid != (uid_t)VNOVAL) {
604 		if ((ap->a_cred->cr_uid != node->uid) &&
605 		    (!groupmember(node->gid, ap->a_cred))) {
606 			error = priv_check(curthread, PRIV_VFS_CHOWN);
607 			if (error)
608 				goto out;
609 		}
610 		node->gid = vap->va_gid;
611 	}
612 
613 	if (vap->va_mode != (mode_t)VNOVAL) {
614 		if (ap->a_cred->cr_uid != node->uid) {
615 			error = priv_check(curthread, PRIV_VFS_ADMIN);
616 			if (error)
617 				goto out;
618 		}
619 		node->mode = vap->va_mode;
620 	}
621 
622 out:
623 	node_sync_dev_set(node);
624 	nanotime(&node->ctime);
625 	lockmgr(&devfs_lock, LK_RELEASE);
626 
627 	return error;
628 }
629 
630 
631 static int
632 devfs_readlink(struct vop_readlink_args *ap)
633 {
634 	struct devfs_node *node = DEVFS_NODE(ap->a_vp);
635 	int ret;
636 
637 	if (!devfs_node_is_accessible(node))
638 		return ENOENT;
639 
640 	lockmgr(&devfs_lock, LK_EXCLUSIVE);
641 	ret = uiomove(node->symlink_name, node->symlink_namelen, ap->a_uio);
642 	lockmgr(&devfs_lock, LK_RELEASE);
643 
644 	return ret;
645 }
646 
647 
648 static int
649 devfs_print(struct vop_print_args *ap)
650 {
651 	return (0);
652 }
653 
654 
655 static int
656 devfs_nsymlink(struct vop_nsymlink_args *ap)
657 {
658 	struct devfs_node *dnode = DEVFS_NODE(ap->a_dvp);
659 	struct devfs_node *node;
660 	size_t targetlen;
661 
662 	if (!devfs_node_is_accessible(dnode))
663 		return ENOENT;
664 
665 	ap->a_vap->va_type = VLNK;
666 
667 	if ((dnode->node_type != Proot) && (dnode->node_type != Pdir))
668 		goto out;
669 
670 	lockmgr(&devfs_lock, LK_EXCLUSIVE);
671 	devfs_allocvp(ap->a_dvp->v_mount, ap->a_vpp, Plink,
672 		      ap->a_nch->ncp->nc_name, dnode, NULL);
673 
674 	targetlen = strlen(ap->a_target);
675 	if (*ap->a_vpp) {
676 		node = DEVFS_NODE(*ap->a_vpp);
677 		node->flags |= DEVFS_USER_CREATED;
678 		node->symlink_namelen = targetlen;
679 		node->symlink_name = kmalloc(targetlen + 1, M_DEVFS, M_WAITOK);
680 		memcpy(node->symlink_name, ap->a_target, targetlen);
681 		node->symlink_name[targetlen] = '\0';
682 		cache_setunresolved(ap->a_nch);
683 		cache_setvp(ap->a_nch, *ap->a_vpp);
684 	}
685 	lockmgr(&devfs_lock, LK_RELEASE);
686 out:
687 	return ((*ap->a_vpp == NULL) ? ENOTDIR : 0);
688 }
689 
690 
691 static int
692 devfs_nremove(struct vop_nremove_args *ap)
693 {
694 	struct devfs_node *dnode = DEVFS_NODE(ap->a_dvp);
695 	struct devfs_node *node;
696 	struct namecache *ncp;
697 	int error = ENOENT;
698 
699 	ncp = ap->a_nch->ncp;
700 
701 	if (!devfs_node_is_accessible(dnode))
702 		return ENOENT;
703 
704 	lockmgr(&devfs_lock, LK_EXCLUSIVE);
705 
706 	if ((dnode->node_type != Proot) && (dnode->node_type != Pdir))
707 		goto out;
708 
709 	TAILQ_FOREACH(node, DEVFS_DENODE_HEAD(dnode), link) {
710 		if (ncp->nc_nlen != node->d_dir.d_namlen)
711 			continue;
712 		if (memcmp(ncp->nc_name, node->d_dir.d_name, ncp->nc_nlen))
713 			continue;
714 
715 		/*
716 		 * only allow removal of user created stuff (e.g. symlinks)
717 		 */
718 		if ((node->flags & DEVFS_USER_CREATED) == 0) {
719 			error = EPERM;
720 			goto out;
721 		} else {
722 			if (node->v_node)
723 				cache_inval_vp(node->v_node, CINV_DESTROY);
724 			devfs_unlinkp(node);
725 			error = 0;
726 			break;
727 		}
728 	}
729 
730 	cache_setunresolved(ap->a_nch);
731 	cache_setvp(ap->a_nch, NULL);
732 
733 out:
734 	lockmgr(&devfs_lock, LK_RELEASE);
735 	return error;
736 }
737 
738 
739 static int
740 devfs_spec_open(struct vop_open_args *ap)
741 {
742 	struct vnode *vp = ap->a_vp;
743 	struct vnode *orig_vp = NULL;
744 	struct devfs_node *node = DEVFS_NODE(vp);
745 	struct devfs_node *newnode;
746 	cdev_t dev, ndev = NULL;
747 	int error = 0;
748 
749 	if (node) {
750 		if (node->d_dev == NULL)
751 			return ENXIO;
752 		if (!devfs_node_is_accessible(node))
753 			return ENOENT;
754 	}
755 
756 	if ((dev = vp->v_rdev) == NULL)
757 		return ENXIO;
758 
759 	if (node && ap->a_fp) {
760 		devfs_debug(DEVFS_DEBUG_DEBUG, "devfs_spec_open: -1.1-\n");
761 		lockmgr(&devfs_lock, LK_EXCLUSIVE);
762 
763 		ndev = devfs_clone(dev, node->d_dir.d_name, node->d_dir.d_namlen,
764 						ap->a_mode, ap->a_cred);
765 		if (ndev != NULL) {
766 			newnode = devfs_create_device_node(
767 					DEVFS_MNTDATA(vp->v_mount)->root_node,
768 					ndev, NULL, NULL);
769 			/* XXX: possibly destroy device if this happens */
770 
771 			if (newnode != NULL) {
772 				dev = ndev;
773 				devfs_link_dev(dev);
774 
775 				devfs_debug(DEVFS_DEBUG_DEBUG,
776 						"parent here is: %s, node is: |%s|\n",
777 						((node->parent->node_type == Proot) ?
778 						"ROOT!" : node->parent->d_dir.d_name),
779 						newnode->d_dir.d_name);
780 				devfs_debug(DEVFS_DEBUG_DEBUG,
781 						"test: %s\n",
782 						((struct devfs_node *)(TAILQ_LAST(DEVFS_DENODE_HEAD(node->parent), devfs_node_head)))->d_dir.d_name);
783 
784 				/*
785 				 * orig_vp is set to the original vp if we cloned.
786 				 */
787 				/* node->flags |= DEVFS_CLONED; */
788 				devfs_allocv(&vp, newnode);
789 				orig_vp = ap->a_vp;
790 				ap->a_vp = vp;
791 			}
792 		}
793 		lockmgr(&devfs_lock, LK_RELEASE);
794 	}
795 
796 	devfs_debug(DEVFS_DEBUG_DEBUG,
797 		    "devfs_spec_open() called on %s! \n",
798 		    dev->si_name);
799 
800 	/*
801 	 * Make this field valid before any I/O in ->d_open
802 	 */
803 	if (!dev->si_iosize_max)
804 		dev->si_iosize_max = DFLTPHYS;
805 
806 	if (dev_dflags(dev) & D_TTY)
807 		vp->v_flag |= VISTTY;
808 
809 	vn_unlock(vp);
810 	error = dev_dopen(dev, ap->a_mode, S_IFCHR, ap->a_cred);
811 	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
812 
813 	/*
814 	 * Clean up any cloned vp if we error out.
815 	 */
816 	if (error) {
817 		if (orig_vp) {
818 			vput(vp);
819 			ap->a_vp = orig_vp;
820 			/* orig_vp = NULL; */
821 		}
822 		return error;
823 	}
824 
825 
826 	if (dev_dflags(dev) & D_TTY) {
827 		if (dev->si_tty) {
828 			struct tty *tp;
829 			tp = dev->si_tty;
830 			if (!tp->t_stop) {
831 				devfs_debug(DEVFS_DEBUG_DEBUG,
832 					    "devfs: no t_stop\n");
833 				tp->t_stop = nottystop;
834 			}
835 		}
836 	}
837 
838 
839 	if (vn_isdisk(vp, NULL)) {
840 		if (!dev->si_bsize_phys)
841 			dev->si_bsize_phys = DEV_BSIZE;
842 		vinitvmio(vp, IDX_TO_OFF(INT_MAX));
843 	}
844 
845 	vop_stdopen(ap);
846 #if 0
847 	if (node)
848 		nanotime(&node->atime);
849 #endif
850 
851 	if (orig_vp)
852 		vn_unlock(vp);
853 
854 	/* Ugly pty magic, to make pty devices appear once they are opened */
855 	if (node && (node->flags & DEVFS_PTY) == DEVFS_PTY)
856 		node->flags &= ~DEVFS_INVISIBLE;
857 
858 	if (ap->a_fp) {
859 		ap->a_fp->f_type = DTYPE_VNODE;
860 		ap->a_fp->f_flag = ap->a_mode & FMASK;
861 		ap->a_fp->f_ops = &devfs_dev_fileops;
862 		ap->a_fp->f_data = vp;
863 	}
864 
865 	return 0;
866 }
867 
868 
869 static int
870 devfs_spec_close(struct vop_close_args *ap)
871 {
872 	struct devfs_node *node = DEVFS_NODE(ap->a_vp);
873 	struct proc *p = curproc;
874 	struct vnode *vp = ap->a_vp;
875 	cdev_t dev = vp->v_rdev;
876 	int error = 0;
877 	int needrelock;
878 
879 	devfs_debug(DEVFS_DEBUG_DEBUG,
880 		    "devfs_spec_close() called on %s! \n",
881 		    dev->si_name);
882 
883 	/*
884 	 * A couple of hacks for devices and tty devices.  The
885 	 * vnode ref count cannot be used to figure out the
886 	 * last close, but we can use v_opencount now that
887 	 * revoke works properly.
888 	 *
889 	 * Detect the last close on a controlling terminal and clear
890 	 * the session (half-close).
891 	 */
892 	if (dev)
893 		reference_dev(dev);
894 
895 	if (p && vp->v_opencount <= 1 && vp == p->p_session->s_ttyvp) {
896 		p->p_session->s_ttyvp = NULL;
897 		vrele(vp);
898 	}
899 
900 	/*
901 	 * Vnodes can be opened and closed multiple times.  Do not really
902 	 * close the device unless (1) it is being closed forcibly,
903 	 * (2) the device wants to track closes, or (3) this is the last
904 	 * vnode doing its last close on the device.
905 	 *
906 	 * XXX the VXLOCK (force close) case can leave vnodes referencing
907 	 * a closed device.  This might not occur now that our revoke is
908 	 * fixed.
909 	 */
910 	devfs_debug(DEVFS_DEBUG_DEBUG, "devfs_spec_close() -1- \n");
911 	if (dev && ((vp->v_flag & VRECLAIMED) ||
912 	    (dev_dflags(dev) & D_TRACKCLOSE) ||
913 	    (vp->v_opencount == 1))) {
914 		/*
915 		 * Unlock around dev_dclose()
916 		 */
917 		needrelock = 0;
918 		if (vn_islocked(vp)) {
919 			needrelock = 1;
920 			vn_unlock(vp);
921 		}
922 		error = dev_dclose(dev, ap->a_fflag, S_IFCHR);
923 
924 		/*
925 		 * Ugly pty magic, to make pty devices disappear again once
926 		 * they are closed
927 		 */
928 		if (node && (node->flags & DEVFS_PTY) == DEVFS_PTY)
929 			node->flags |= DEVFS_INVISIBLE;
930 
931 		if (needrelock)
932 			vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
933 	} else {
934 		error = 0;
935 	}
936 	devfs_debug(DEVFS_DEBUG_DEBUG, "devfs_spec_close() -2- \n");
937 
938 	/*
939 	 * Track the actual opens and closes on the vnode.  The last close
940 	 * disassociates the rdev.  If the rdev is already disassociated or
941 	 * the opencount is already 0, the vnode might have been revoked
942 	 * and no further opencount tracking occurs.
943 	 */
944 	if (dev)
945 		release_dev(dev);
946 	if (vp->v_opencount > 0)
947 		vop_stdclose(ap);
948 	return(error);
949 
950 }
951 
952 
953 static int
954 devfs_specf_close(struct file *fp)
955 {
956 	struct vnode *vp = (struct vnode *)fp->f_data;
957 	int error;
958 
959 	get_mplock();
960 	fp->f_ops = &badfileops;
961 	error = vn_close(vp, fp->f_flag);
962 	rel_mplock();
963 
964 	return (error);
965 }
966 
967 
968 /*
969  * Device-optimized file table vnode read routine.
970  *
971  * This bypasses the VOP table and talks directly to the device.  Most
972  * filesystems just route to specfs and can make this optimization.
973  *
974  * MPALMOSTSAFE - acquires mplock
975  */
976 static int
977 devfs_specf_read(struct file *fp, struct uio *uio,
978 		 struct ucred *cred, int flags)
979 {
980 	struct devfs_node *node;
981 	struct vnode *vp;
982 	int ioflag;
983 	int error;
984 	cdev_t dev;
985 
986 	get_mplock();
987 	KASSERT(uio->uio_td == curthread,
988 		("uio_td %p is not td %p", uio->uio_td, curthread));
989 
990 	vp = (struct vnode *)fp->f_data;
991 	if (vp == NULL || vp->v_type == VBAD) {
992 		error = EBADF;
993 		goto done;
994 	}
995 	node = DEVFS_NODE(vp);
996 
997 	if ((dev = vp->v_rdev) == NULL) {
998 		error = EBADF;
999 		goto done;
1000 	}
1001 
1002 	reference_dev(dev);
1003 
1004 	if (uio->uio_resid == 0) {
1005 		error = 0;
1006 		goto done;
1007 	}
1008 	if ((flags & O_FOFFSET) == 0)
1009 		uio->uio_offset = fp->f_offset;
1010 
1011 	ioflag = 0;
1012 	if (flags & O_FBLOCKING) {
1013 		/* ioflag &= ~IO_NDELAY; */
1014 	} else if (flags & O_FNONBLOCKING) {
1015 		ioflag |= IO_NDELAY;
1016 	} else if (fp->f_flag & FNONBLOCK) {
1017 		ioflag |= IO_NDELAY;
1018 	}
1019 	if (flags & O_FBUFFERED) {
1020 		/* ioflag &= ~IO_DIRECT; */
1021 	} else if (flags & O_FUNBUFFERED) {
1022 		ioflag |= IO_DIRECT;
1023 	} else if (fp->f_flag & O_DIRECT) {
1024 		ioflag |= IO_DIRECT;
1025 	}
1026 	ioflag |= sequential_heuristic(uio, fp);
1027 
1028 	error = dev_dread(dev, uio, ioflag);
1029 
1030 	release_dev(dev);
1031 	if (node)
1032 		nanotime(&node->atime);
1033 	if ((flags & O_FOFFSET) == 0)
1034 		fp->f_offset = uio->uio_offset;
1035 	fp->f_nextoff = uio->uio_offset;
1036 done:
1037 	rel_mplock();
1038 	return (error);
1039 }
1040 
1041 
1042 static int
1043 devfs_specf_write(struct file *fp, struct uio *uio,
1044 		  struct ucred *cred, int flags)
1045 {
1046 	struct devfs_node *node;
1047 	struct vnode *vp;
1048 	int ioflag;
1049 	int error;
1050 	cdev_t dev;
1051 
1052 	get_mplock();
1053 	KASSERT(uio->uio_td == curthread,
1054 		("uio_td %p is not p %p", uio->uio_td, curthread));
1055 
1056 	vp = (struct vnode *)fp->f_data;
1057 	if (vp == NULL || vp->v_type == VBAD) {
1058 		error = EBADF;
1059 		goto done;
1060 	}
1061 	node = DEVFS_NODE(vp);
1062 	if (vp->v_type == VREG)
1063 		bwillwrite(uio->uio_resid);
1064 	vp = (struct vnode *)fp->f_data;
1065 
1066 	if ((dev = vp->v_rdev) == NULL) {
1067 		error = EBADF;
1068 		goto done;
1069 	}
1070 	reference_dev(dev);
1071 
1072 	if ((flags & O_FOFFSET) == 0)
1073 		uio->uio_offset = fp->f_offset;
1074 
1075 	ioflag = IO_UNIT;
1076 	if (vp->v_type == VREG &&
1077 	   ((fp->f_flag & O_APPEND) || (flags & O_FAPPEND))) {
1078 		ioflag |= IO_APPEND;
1079 	}
1080 
1081 	if (flags & O_FBLOCKING) {
1082 		/* ioflag &= ~IO_NDELAY; */
1083 	} else if (flags & O_FNONBLOCKING) {
1084 		ioflag |= IO_NDELAY;
1085 	} else if (fp->f_flag & FNONBLOCK) {
1086 		ioflag |= IO_NDELAY;
1087 	}
1088 	if (flags & O_FBUFFERED) {
1089 		/* ioflag &= ~IO_DIRECT; */
1090 	} else if (flags & O_FUNBUFFERED) {
1091 		ioflag |= IO_DIRECT;
1092 	} else if (fp->f_flag & O_DIRECT) {
1093 		ioflag |= IO_DIRECT;
1094 	}
1095 	if (flags & O_FASYNCWRITE) {
1096 		/* ioflag &= ~IO_SYNC; */
1097 	} else if (flags & O_FSYNCWRITE) {
1098 		ioflag |= IO_SYNC;
1099 	} else if (fp->f_flag & O_FSYNC) {
1100 		ioflag |= IO_SYNC;
1101 	}
1102 
1103 	if (vp->v_mount && (vp->v_mount->mnt_flag & MNT_SYNCHRONOUS))
1104 		ioflag |= IO_SYNC;
1105 	ioflag |= sequential_heuristic(uio, fp);
1106 
1107 	error = dev_dwrite(dev, uio, ioflag);
1108 
1109 	release_dev(dev);
1110 	if (node) {
1111 		nanotime(&node->atime);
1112 		nanotime(&node->mtime);
1113 	}
1114 
1115 	if ((flags & O_FOFFSET) == 0)
1116 		fp->f_offset = uio->uio_offset;
1117 	fp->f_nextoff = uio->uio_offset;
1118 done:
1119 	rel_mplock();
1120 	return (error);
1121 }
1122 
1123 
1124 static int
1125 devfs_specf_stat(struct file *fp, struct stat *sb, struct ucred *cred)
1126 {
1127 	struct vnode *vp;
1128 	int error;
1129 
1130 	get_mplock();
1131 	vp = (struct vnode *)fp->f_data;
1132 	error = vn_stat(vp, sb, cred);
1133 	if (error) {
1134 		rel_mplock();
1135 		return (error);
1136 	}
1137 
1138 	struct vattr vattr;
1139 	struct vattr *vap;
1140 	u_short mode;
1141 	cdev_t dev;
1142 
1143 	vap = &vattr;
1144 	error = VOP_GETATTR(vp, vap);
1145 	if (error) {
1146 		rel_mplock();
1147 		return (error);
1148 	}
1149 
1150 	/*
1151 	 * Zero the spare stat fields
1152 	 */
1153 	sb->st_lspare = 0;
1154 	sb->st_qspare = 0;
1155 
1156 	/*
1157 	 * Copy from vattr table ... or not in case it's a cloned device
1158 	 */
1159 	if (vap->va_fsid != VNOVAL)
1160 		sb->st_dev = vap->va_fsid;
1161 	else
1162 		sb->st_dev = vp->v_mount->mnt_stat.f_fsid.val[0];
1163 
1164 	sb->st_ino = vap->va_fileid;
1165 
1166 	mode = vap->va_mode;
1167 	mode |= S_IFCHR;
1168 	sb->st_mode = mode;
1169 
1170 	if (vap->va_nlink > (nlink_t)-1)
1171 		sb->st_nlink = (nlink_t)-1;
1172 	else
1173 		sb->st_nlink = vap->va_nlink;
1174 	sb->st_uid = vap->va_uid;
1175 	sb->st_gid = vap->va_gid;
1176 	sb->st_rdev = dev2udev(DEVFS_NODE(vp)->d_dev);
1177 	sb->st_size = vap->va_size;
1178 	sb->st_atimespec = vap->va_atime;
1179 	sb->st_mtimespec = vap->va_mtime;
1180 	sb->st_ctimespec = vap->va_ctime;
1181 
1182 	/*
1183 	 * A VCHR and VBLK device may track the last access and last modified
1184 	 * time independantly of the filesystem.  This is particularly true
1185 	 * because device read and write calls may bypass the filesystem.
1186 	 */
1187 	if (vp->v_type == VCHR || vp->v_type == VBLK) {
1188 		dev = vp->v_rdev;
1189 		if (dev != NULL) {
1190 			if (dev->si_lastread) {
1191 				sb->st_atimespec.tv_sec = dev->si_lastread;
1192 				sb->st_atimespec.tv_nsec = 0;
1193 			}
1194 			if (dev->si_lastwrite) {
1195 				sb->st_atimespec.tv_sec = dev->si_lastwrite;
1196 				sb->st_atimespec.tv_nsec = 0;
1197 			}
1198 		}
1199 	}
1200 
1201         /*
1202 	 * According to www.opengroup.org, the meaning of st_blksize is
1203 	 *   "a filesystem-specific preferred I/O block size for this
1204 	 *    object.  In some filesystem types, this may vary from file
1205 	 *    to file"
1206 	 * Default to PAGE_SIZE after much discussion.
1207 	 */
1208 
1209 	sb->st_blksize = PAGE_SIZE;
1210 
1211 	sb->st_flags = vap->va_flags;
1212 
1213 	error = priv_check_cred(cred, PRIV_VFS_GENERATION, 0);
1214 	if (error)
1215 		sb->st_gen = 0;
1216 	else
1217 		sb->st_gen = (u_int32_t)vap->va_gen;
1218 
1219 	sb->st_blocks = vap->va_bytes / S_BLKSIZE;
1220 	sb->st_fsmid = vap->va_fsmid;
1221 
1222 	rel_mplock();
1223 	return (0);
1224 }
1225 
1226 
1227 static int
1228 devfs_specf_kqfilter(struct file *fp, struct knote *kn)
1229 {
1230 	struct devfs_node *node;
1231 	struct vnode *vp;
1232 	int error;
1233 	cdev_t dev;
1234 
1235 	get_mplock();
1236 
1237 	vp = (struct vnode *)fp->f_data;
1238 	if (vp == NULL || vp->v_type == VBAD) {
1239 		error = EBADF;
1240 		goto done;
1241 	}
1242 	node = DEVFS_NODE(vp);
1243 
1244 	if ((dev = vp->v_rdev) == NULL) {
1245 		error = EBADF;
1246 		goto done;
1247 	}
1248 	reference_dev(dev);
1249 
1250 	error = dev_dkqfilter(dev, kn);
1251 
1252 	release_dev(dev);
1253 
1254 done:
1255 	rel_mplock();
1256 	return (error);
1257 }
1258 
1259 
1260 static int
1261 devfs_specf_poll(struct file *fp, int events, struct ucred *cred)
1262 {
1263 	struct devfs_node *node;
1264 	struct vnode *vp;
1265 	int error;
1266 	cdev_t dev;
1267 
1268 	get_mplock();
1269 
1270 	vp = (struct vnode *)fp->f_data;
1271 	if (vp == NULL || vp->v_type == VBAD) {
1272 		error = EBADF;
1273 		goto done;
1274 	}
1275 	node = DEVFS_NODE(vp);
1276 
1277 	if ((dev = vp->v_rdev) == NULL) {
1278 		error = EBADF;
1279 		goto done;
1280 	}
1281 	reference_dev(dev);
1282 	error = dev_dpoll(dev, events);
1283 
1284 	release_dev(dev);
1285 
1286 #if 0
1287 	if (node)
1288 		nanotime(&node->atime);
1289 #endif
1290 done:
1291 	rel_mplock();
1292 	return (error);
1293 }
1294 
1295 
1296 /*
1297  * MPALMOSTSAFE - acquires mplock
1298  */
1299 static int
1300 devfs_specf_ioctl(struct file *fp, u_long com, caddr_t data,
1301 		  struct ucred *ucred, struct sysmsg *msg)
1302 {
1303 	struct devfs_node *node;
1304 	struct vnode *vp;
1305 	struct vnode *ovp;
1306 	cdev_t	dev;
1307 	int error;
1308 	struct fiodname_args *name_args;
1309 	size_t namlen;
1310 	const char *name;
1311 
1312 	get_mplock();
1313 	vp = ((struct vnode *)fp->f_data);
1314 	if ((dev = vp->v_rdev) == NULL) {
1315 		error = EBADF;		/* device was revoked */
1316 		goto out;
1317 	}
1318 
1319 	node = DEVFS_NODE(vp);
1320 
1321 	devfs_debug(DEVFS_DEBUG_DEBUG,
1322 		    "devfs_specf_ioctl() called! for dev %s\n",
1323 		    dev->si_name);
1324 
1325 	if (com == FIODTYPE) {
1326 		*(int *)data = dev_dflags(dev) & D_TYPEMASK;
1327 		error = 0;
1328 		goto out;
1329 	} else if (com == FIODNAME) {
1330 		name_args = (struct fiodname_args *)data;
1331 		name = dev->si_name;
1332 		namlen = strlen(name) + 1;
1333 
1334 		devfs_debug(DEVFS_DEBUG_DEBUG,
1335 			    "ioctl, got: FIODNAME for %s\n", name);
1336 
1337 		if (namlen <= name_args->len)
1338 			error = copyout(dev->si_name, name_args->name, namlen);
1339 		else
1340 			error = EINVAL;
1341 
1342 		devfs_debug(DEVFS_DEBUG_DEBUG,
1343 			    "ioctl stuff: error: %d\n", error);
1344 		goto out;
1345 	}
1346 	reference_dev(dev);
1347 	error = dev_dioctl(dev, com, data, fp->f_flag, ucred, msg);
1348 	release_dev(dev);
1349 #if 0
1350 	if (node) {
1351 		nanotime(&node->atime);
1352 		nanotime(&node->mtime);
1353 	}
1354 #endif
1355 
1356 	if (com == TIOCSCTTY) {
1357 		devfs_debug(DEVFS_DEBUG_DEBUG,
1358 			    "devfs_specf_ioctl: got TIOCSCTTY on %s\n",
1359 			    dev->si_name);
1360 	}
1361 	if (error == 0 && com == TIOCSCTTY) {
1362 		struct proc *p = curthread->td_proc;
1363 		struct session *sess;
1364 
1365 		devfs_debug(DEVFS_DEBUG_DEBUG,
1366 			    "devfs_specf_ioctl: dealing with TIOCSCTTY on %s\n",
1367 			    dev->si_name);
1368 		if (p == NULL) {
1369 			error = ENOTTY;
1370 			goto out;
1371 		}
1372 		sess = p->p_session;
1373 
1374 		/*
1375 		 * Do nothing if reassigning same control tty
1376 		 */
1377 		if (sess->s_ttyvp == vp) {
1378 			error = 0;
1379 			goto out;
1380 		}
1381 
1382 		/*
1383 		 * Get rid of reference to old control tty
1384 		 */
1385 		ovp = sess->s_ttyvp;
1386 		vref(vp);
1387 		sess->s_ttyvp = vp;
1388 		if (ovp)
1389 			vrele(ovp);
1390 	}
1391 
1392 out:
1393 	rel_mplock();
1394 	devfs_debug(DEVFS_DEBUG_DEBUG, "devfs_specf_ioctl() finished! \n");
1395 	return (error);
1396 }
1397 
1398 
1399 static int
1400 devfs_spec_fsync(struct vop_fsync_args *ap)
1401 {
1402 	struct vnode *vp = ap->a_vp;
1403 	int error;
1404 
1405 	if (!vn_isdisk(vp, NULL))
1406 		return (0);
1407 
1408 	/*
1409 	 * Flush all dirty buffers associated with a block device.
1410 	 */
1411 	error = vfsync(vp, ap->a_waitfor, 10000, NULL, NULL);
1412 	return (error);
1413 }
1414 
1415 static int
1416 devfs_spec_read(struct vop_read_args *ap)
1417 {
1418 	struct devfs_node *node;
1419 	struct vnode *vp;
1420 	struct uio *uio;
1421 	cdev_t dev;
1422 	int error;
1423 
1424 	vp = ap->a_vp;
1425 	dev = vp->v_rdev;
1426 	uio = ap->a_uio;
1427 	node = DEVFS_NODE(vp);
1428 
1429 	if (dev == NULL)		/* device was revoked */
1430 		return (EBADF);
1431 	if (uio->uio_resid == 0)
1432 		return (0);
1433 
1434 	vn_unlock(vp);
1435 	error = dev_dread(dev, uio, ap->a_ioflag);
1436 	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
1437 
1438 	if (node)
1439 		nanotime(&node->atime);
1440 
1441 	return (error);
1442 }
1443 
1444 /*
1445  * Vnode op for write
1446  *
1447  * spec_write(struct vnode *a_vp, struct uio *a_uio, int a_ioflag,
1448  *	      struct ucred *a_cred)
1449  */
1450 static int
1451 devfs_spec_write(struct vop_write_args *ap)
1452 {
1453 	struct devfs_node *node;
1454 	struct vnode *vp;
1455 	struct uio *uio;
1456 	cdev_t dev;
1457 	int error;
1458 
1459 	vp = ap->a_vp;
1460 	dev = vp->v_rdev;
1461 	uio = ap->a_uio;
1462 	node = DEVFS_NODE(vp);
1463 
1464 	KKASSERT(uio->uio_segflg != UIO_NOCOPY);
1465 
1466 	if (dev == NULL)		/* device was revoked */
1467 		return (EBADF);
1468 
1469 	vn_unlock(vp);
1470 	error = dev_dwrite(dev, uio, ap->a_ioflag);
1471 	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
1472 
1473 	if (node) {
1474 		nanotime(&node->atime);
1475 		nanotime(&node->mtime);
1476 	}
1477 
1478 	return (error);
1479 }
1480 
1481 /*
1482  * Device ioctl operation.
1483  *
1484  * spec_ioctl(struct vnode *a_vp, int a_command, caddr_t a_data,
1485  *	      int a_fflag, struct ucred *a_cred, struct sysmsg *msg)
1486  */
1487 static int
1488 devfs_spec_ioctl(struct vop_ioctl_args *ap)
1489 {
1490 	struct vnode *vp = ap->a_vp;
1491 	struct devfs_node *node;
1492 	cdev_t dev;
1493 
1494 	if ((dev = vp->v_rdev) == NULL)
1495 		return (EBADF);		/* device was revoked */
1496 	node = DEVFS_NODE(vp);
1497 
1498 #if 0
1499 	if (node) {
1500 		nanotime(&node->atime);
1501 		nanotime(&node->mtime);
1502 	}
1503 #endif
1504 
1505 	return (dev_dioctl(dev, ap->a_command, ap->a_data, ap->a_fflag,
1506 			   ap->a_cred, ap->a_sysmsg));
1507 }
1508 
1509 /*
1510  * spec_poll(struct vnode *a_vp, int a_events, struct ucred *a_cred)
1511  */
1512 /* ARGSUSED */
1513 static int
1514 devfs_spec_poll(struct vop_poll_args *ap)
1515 {
1516 	struct vnode *vp = ap->a_vp;
1517 	struct devfs_node *node;
1518 	cdev_t dev;
1519 
1520 	if ((dev = vp->v_rdev) == NULL)
1521 		return (EBADF);		/* device was revoked */
1522 	node = DEVFS_NODE(vp);
1523 
1524 #if 0
1525 	if (node)
1526 		nanotime(&node->atime);
1527 #endif
1528 
1529 	return (dev_dpoll(dev, ap->a_events));
1530 }
1531 
1532 /*
1533  * spec_kqfilter(struct vnode *a_vp, struct knote *a_kn)
1534  */
1535 /* ARGSUSED */
1536 static int
1537 devfs_spec_kqfilter(struct vop_kqfilter_args *ap)
1538 {
1539 	struct vnode *vp = ap->a_vp;
1540 	struct devfs_node *node;
1541 	cdev_t dev;
1542 
1543 	if ((dev = vp->v_rdev) == NULL)
1544 		return (EBADF);		/* device was revoked */
1545 	node = DEVFS_NODE(vp);
1546 
1547 #if 0
1548 	if (node)
1549 		nanotime(&node->atime);
1550 #endif
1551 
1552 	return (dev_dkqfilter(dev, ap->a_kn));
1553 }
1554 
1555 /*
1556  * Convert a vnode strategy call into a device strategy call.  Vnode strategy
1557  * calls are not limited to device DMA limits so we have to deal with the
1558  * case.
1559  *
1560  * spec_strategy(struct vnode *a_vp, struct bio *a_bio)
1561  */
1562 static int
1563 devfs_spec_strategy(struct vop_strategy_args *ap)
1564 {
1565 	struct bio *bio = ap->a_bio;
1566 	struct buf *bp = bio->bio_buf;
1567 	struct buf *nbp;
1568 	struct vnode *vp;
1569 	struct mount *mp;
1570 	int chunksize;
1571 	int maxiosize;
1572 
1573 	if (bp->b_cmd != BUF_CMD_READ && LIST_FIRST(&bp->b_dep) != NULL)
1574 		buf_start(bp);
1575 
1576 	/*
1577 	 * Collect statistics on synchronous and asynchronous read
1578 	 * and write counts for disks that have associated filesystems.
1579 	 */
1580 	vp = ap->a_vp;
1581 	KKASSERT(vp->v_rdev != NULL);	/* XXX */
1582 	if (vn_isdisk(vp, NULL) && (mp = vp->v_rdev->si_mountpoint) != NULL) {
1583 		if (bp->b_cmd == BUF_CMD_READ) {
1584 			if (bp->b_flags & BIO_SYNC)
1585 				mp->mnt_stat.f_syncreads++;
1586 			else
1587 				mp->mnt_stat.f_asyncreads++;
1588 		} else {
1589 			if (bp->b_flags & BIO_SYNC)
1590 				mp->mnt_stat.f_syncwrites++;
1591 			else
1592 				mp->mnt_stat.f_asyncwrites++;
1593 		}
1594 	}
1595 
1596         /*
1597          * Device iosize limitations only apply to read and write.  Shortcut
1598          * the I/O if it fits.
1599          */
1600 	if ((maxiosize = vp->v_rdev->si_iosize_max) == 0) {
1601 		devfs_debug(DEVFS_DEBUG_DEBUG,
1602 			    "%s: si_iosize_max not set!\n",
1603 			    dev_dname(vp->v_rdev));
1604 		maxiosize = MAXPHYS;
1605 	}
1606 #if SPEC_CHAIN_DEBUG & 2
1607 	maxiosize = 4096;
1608 #endif
1609         if (bp->b_bcount <= maxiosize ||
1610             (bp->b_cmd != BUF_CMD_READ && bp->b_cmd != BUF_CMD_WRITE)) {
1611                 dev_dstrategy_chain(vp->v_rdev, bio);
1612                 return (0);
1613         }
1614 
1615 	/*
1616 	 * Clone the buffer and set up an I/O chain to chunk up the I/O.
1617 	 */
1618 	nbp = kmalloc(sizeof(*bp), M_DEVBUF, M_INTWAIT|M_ZERO);
1619 	initbufbio(nbp);
1620 	buf_dep_init(nbp);
1621 	BUF_LOCKINIT(nbp);
1622 	BUF_LOCK(nbp, LK_EXCLUSIVE);
1623 	BUF_KERNPROC(nbp);
1624 	nbp->b_vp = vp;
1625 	nbp->b_flags = B_PAGING | (bp->b_flags & B_BNOCLIP);
1626 	nbp->b_data = bp->b_data;
1627 	nbp->b_bio1.bio_done = devfs_spec_strategy_done;
1628 	nbp->b_bio1.bio_offset = bio->bio_offset;
1629 	nbp->b_bio1.bio_caller_info1.ptr = bio;
1630 
1631 	/*
1632 	 * Start the first transfer
1633 	 */
1634 	if (vn_isdisk(vp, NULL))
1635 		chunksize = vp->v_rdev->si_bsize_phys;
1636 	else
1637 		chunksize = DEV_BSIZE;
1638 	chunksize = maxiosize / chunksize * chunksize;
1639 #if SPEC_CHAIN_DEBUG & 1
1640 	devfs_debug(DEVFS_DEBUG_DEBUG,
1641 		    "spec_strategy chained I/O chunksize=%d\n",
1642 		    chunksize);
1643 #endif
1644 	nbp->b_cmd = bp->b_cmd;
1645 	nbp->b_bcount = chunksize;
1646 	nbp->b_bufsize = chunksize;	/* used to detect a short I/O */
1647 	nbp->b_bio1.bio_caller_info2.index = chunksize;
1648 
1649 #if SPEC_CHAIN_DEBUG & 1
1650 	devfs_debug(DEVFS_DEBUG_DEBUG,
1651 		    "spec_strategy: chain %p offset %d/%d bcount %d\n",
1652 		    bp, 0, bp->b_bcount, nbp->b_bcount);
1653 #endif
1654 
1655 	dev_dstrategy(vp->v_rdev, &nbp->b_bio1);
1656 
1657 	if (DEVFS_NODE(vp)) {
1658 		nanotime(&DEVFS_NODE(vp)->atime);
1659 		nanotime(&DEVFS_NODE(vp)->mtime);
1660 	}
1661 
1662 	return (0);
1663 }
1664 
1665 /*
1666  * Chunked up transfer completion routine - chain transfers until done
1667  */
1668 static
1669 void
1670 devfs_spec_strategy_done(struct bio *nbio)
1671 {
1672 	struct buf *nbp = nbio->bio_buf;
1673 	struct bio *bio = nbio->bio_caller_info1.ptr;	/* original bio */
1674 	struct buf *bp = bio->bio_buf;			/* original bp */
1675 	int chunksize = nbio->bio_caller_info2.index;	/* chunking */
1676 	int boffset = nbp->b_data - bp->b_data;
1677 
1678 	if (nbp->b_flags & B_ERROR) {
1679 		/*
1680 		 * An error terminates the chain, propogate the error back
1681 		 * to the original bp
1682 		 */
1683 		bp->b_flags |= B_ERROR;
1684 		bp->b_error = nbp->b_error;
1685 		bp->b_resid = bp->b_bcount - boffset +
1686 			      (nbp->b_bcount - nbp->b_resid);
1687 #if SPEC_CHAIN_DEBUG & 1
1688 		devfs_debug(DEVFS_DEBUG_DEBUG,
1689 			    "spec_strategy: chain %p error %d bcount %d/%d\n",
1690 			    bp, bp->b_error, bp->b_bcount,
1691 			    bp->b_bcount - bp->b_resid);
1692 #endif
1693 		kfree(nbp, M_DEVBUF);
1694 		biodone(bio);
1695 	} else if (nbp->b_resid) {
1696 		/*
1697 		 * A short read or write terminates the chain
1698 		 */
1699 		bp->b_error = nbp->b_error;
1700 		bp->b_resid = bp->b_bcount - boffset +
1701 			      (nbp->b_bcount - nbp->b_resid);
1702 #if SPEC_CHAIN_DEBUG & 1
1703 		devfs_debug(DEVFS_DEBUG_DEBUG,
1704 			    "spec_strategy: chain %p short read(1) "
1705 			    "bcount %d/%d\n",
1706 			    bp, bp->b_bcount - bp->b_resid, bp->b_bcount);
1707 #endif
1708 		kfree(nbp, M_DEVBUF);
1709 		biodone(bio);
1710 	} else if (nbp->b_bcount != nbp->b_bufsize) {
1711 		/*
1712 		 * A short read or write can also occur by truncating b_bcount
1713 		 */
1714 #if SPEC_CHAIN_DEBUG & 1
1715 		devfs_debug(DEVFS_DEBUG_DEBUG,
1716 			    "spec_strategy: chain %p short read(2) "
1717 			    "bcount %d/%d\n",
1718 			    bp, nbp->b_bcount + boffset, bp->b_bcount);
1719 #endif
1720 		bp->b_error = 0;
1721 		bp->b_bcount = nbp->b_bcount + boffset;
1722 		bp->b_resid = nbp->b_resid;
1723 		kfree(nbp, M_DEVBUF);
1724 		biodone(bio);
1725 	} else if (nbp->b_bcount + boffset == bp->b_bcount) {
1726 		/*
1727 		 * No more data terminates the chain
1728 		 */
1729 #if SPEC_CHAIN_DEBUG & 1
1730 		devfs_debug(DEVFS_DEBUG_DEBUG,
1731 			    "spec_strategy: chain %p finished bcount %d\n",
1732 			    bp, bp->b_bcount);
1733 #endif
1734 		bp->b_error = 0;
1735 		bp->b_resid = 0;
1736 		kfree(nbp, M_DEVBUF);
1737 		biodone(bio);
1738 	} else {
1739 		/*
1740 		 * Continue the chain
1741 		 */
1742 		boffset += nbp->b_bcount;
1743 		nbp->b_data = bp->b_data + boffset;
1744 		nbp->b_bcount = bp->b_bcount - boffset;
1745 		if (nbp->b_bcount > chunksize)
1746 			nbp->b_bcount = chunksize;
1747 		nbp->b_bio1.bio_done = devfs_spec_strategy_done;
1748 		nbp->b_bio1.bio_offset = bio->bio_offset + boffset;
1749 
1750 #if SPEC_CHAIN_DEBUG & 1
1751 		devfs_debug(DEVFS_DEBUG_DEBUG,
1752 			    "spec_strategy: chain %p offset %d/%d bcount %d\n",
1753 			    bp, boffset, bp->b_bcount, nbp->b_bcount);
1754 #endif
1755 
1756 		dev_dstrategy(nbp->b_vp->v_rdev, &nbp->b_bio1);
1757 	}
1758 }
1759 
1760 /*
1761  * spec_freeblks(struct vnode *a_vp, daddr_t a_addr, daddr_t a_length)
1762  */
1763 static int
1764 devfs_spec_freeblks(struct vop_freeblks_args *ap)
1765 {
1766 	struct buf *bp;
1767 
1768 	/*
1769 	 * XXX: This assumes that strategy does the deed right away.
1770 	 * XXX: this may not be TRTTD.
1771 	 */
1772 	KKASSERT(ap->a_vp->v_rdev != NULL);
1773 	if ((dev_dflags(ap->a_vp->v_rdev) & D_CANFREE) == 0)
1774 		return (0);
1775 	bp = geteblk(ap->a_length);
1776 	bp->b_cmd = BUF_CMD_FREEBLKS;
1777 	bp->b_bio1.bio_offset = ap->a_offset;
1778 	bp->b_bcount = ap->a_length;
1779 	dev_dstrategy(ap->a_vp->v_rdev, &bp->b_bio1);
1780 	return (0);
1781 }
1782 
1783 /*
1784  * Implement degenerate case where the block requested is the block
1785  * returned, and assume that the entire device is contiguous in regards
1786  * to the contiguous block range (runp and runb).
1787  *
1788  * spec_bmap(struct vnode *a_vp, off_t a_loffset,
1789  *	     off_t *a_doffsetp, int *a_runp, int *a_runb)
1790  */
1791 static int
1792 devfs_spec_bmap(struct vop_bmap_args *ap)
1793 {
1794 	if (ap->a_doffsetp != NULL)
1795 		*ap->a_doffsetp = ap->a_loffset;
1796 	if (ap->a_runp != NULL)
1797 		*ap->a_runp = MAXBSIZE;
1798 	if (ap->a_runb != NULL) {
1799 		if (ap->a_loffset < MAXBSIZE)
1800 			*ap->a_runb = (int)ap->a_loffset;
1801 		else
1802 			*ap->a_runb = MAXBSIZE;
1803 	}
1804 	return (0);
1805 }
1806 
1807 
1808 /*
1809  * Special device advisory byte-level locks.
1810  *
1811  * spec_advlock(struct vnode *a_vp, caddr_t a_id, int a_op,
1812  *		struct flock *a_fl, int a_flags)
1813  */
1814 /* ARGSUSED */
1815 static int
1816 devfs_spec_advlock(struct vop_advlock_args *ap)
1817 {
1818 	return ((ap->a_flags & F_POSIX) ? EINVAL : EOPNOTSUPP);
1819 }
1820 
1821 static void
1822 devfs_spec_getpages_iodone(struct bio *bio)
1823 {
1824 	bio->bio_buf->b_cmd = BUF_CMD_DONE;
1825 	wakeup(bio->bio_buf);
1826 }
1827 
1828 /*
1829  * spec_getpages() - get pages associated with device vnode.
1830  *
1831  * Note that spec_read and spec_write do not use the buffer cache, so we
1832  * must fully implement getpages here.
1833  */
1834 static int
1835 devfs_spec_getpages(struct vop_getpages_args *ap)
1836 {
1837 	vm_offset_t kva;
1838 	int error;
1839 	int i, pcount, size;
1840 	struct buf *bp;
1841 	vm_page_t m;
1842 	vm_ooffset_t offset;
1843 	int toff, nextoff, nread;
1844 	struct vnode *vp = ap->a_vp;
1845 	int blksiz;
1846 	int gotreqpage;
1847 
1848 	error = 0;
1849 	pcount = round_page(ap->a_count) / PAGE_SIZE;
1850 
1851 	/*
1852 	 * Calculate the offset of the transfer and do sanity check.
1853 	 */
1854 	offset = IDX_TO_OFF(ap->a_m[0]->pindex) + ap->a_offset;
1855 
1856 	/*
1857 	 * Round up physical size for real devices.  We cannot round using
1858 	 * v_mount's block size data because v_mount has nothing to do with
1859 	 * the device.  i.e. it's usually '/dev'.  We need the physical block
1860 	 * size for the device itself.
1861 	 *
1862 	 * We can't use v_rdev->si_mountpoint because it only exists when the
1863 	 * block device is mounted.  However, we can use v_rdev.
1864 	 */
1865 	if (vn_isdisk(vp, NULL))
1866 		blksiz = vp->v_rdev->si_bsize_phys;
1867 	else
1868 		blksiz = DEV_BSIZE;
1869 
1870 	size = (ap->a_count + blksiz - 1) & ~(blksiz - 1);
1871 
1872 	bp = getpbuf(NULL);
1873 	kva = (vm_offset_t)bp->b_data;
1874 
1875 	/*
1876 	 * Map the pages to be read into the kva.
1877 	 */
1878 	pmap_qenter(kva, ap->a_m, pcount);
1879 
1880 	/* Build a minimal buffer header. */
1881 	bp->b_cmd = BUF_CMD_READ;
1882 	bp->b_bcount = size;
1883 	bp->b_resid = 0;
1884 	bp->b_runningbufspace = size;
1885 	if (size) {
1886 		runningbufspace += bp->b_runningbufspace;
1887 		++runningbufcount;
1888 	}
1889 
1890 	bp->b_bio1.bio_offset = offset;
1891 	bp->b_bio1.bio_done = devfs_spec_getpages_iodone;
1892 
1893 	mycpu->gd_cnt.v_vnodein++;
1894 	mycpu->gd_cnt.v_vnodepgsin += pcount;
1895 
1896 	/* Do the input. */
1897 	vn_strategy(ap->a_vp, &bp->b_bio1);
1898 
1899 	crit_enter();
1900 
1901 	/* We definitely need to be at splbio here. */
1902 	while (bp->b_cmd != BUF_CMD_DONE)
1903 		tsleep(bp, 0, "spread", 0);
1904 
1905 	crit_exit();
1906 
1907 	if (bp->b_flags & B_ERROR) {
1908 		if (bp->b_error)
1909 			error = bp->b_error;
1910 		else
1911 			error = EIO;
1912 	}
1913 
1914 	/*
1915 	 * If EOF is encountered we must zero-extend the result in order
1916 	 * to ensure that the page does not contain garabge.  When no
1917 	 * error occurs, an early EOF is indicated if b_bcount got truncated.
1918 	 * b_resid is relative to b_bcount and should be 0, but some devices
1919 	 * might indicate an EOF with b_resid instead of truncating b_bcount.
1920 	 */
1921 	nread = bp->b_bcount - bp->b_resid;
1922 	if (nread < ap->a_count)
1923 		bzero((caddr_t)kva + nread, ap->a_count - nread);
1924 	pmap_qremove(kva, pcount);
1925 
1926 	gotreqpage = 0;
1927 	for (i = 0, toff = 0; i < pcount; i++, toff = nextoff) {
1928 		nextoff = toff + PAGE_SIZE;
1929 		m = ap->a_m[i];
1930 
1931 		m->flags &= ~PG_ZERO;
1932 
1933 		/*
1934 		 * NOTE: vm_page_undirty/clear_dirty etc do not clear the
1935 		 *	 pmap modified bit.  pmap modified bit should have
1936 		 *	 already been cleared.
1937 		 */
1938 		if (nextoff <= nread) {
1939 			m->valid = VM_PAGE_BITS_ALL;
1940 			vm_page_undirty(m);
1941 		} else if (toff < nread) {
1942 			/*
1943 			 * Since this is a VM request, we have to supply the
1944 			 * unaligned offset to allow vm_page_set_valid()
1945 			 * to zero sub-DEV_BSIZE'd portions of the page.
1946 			 */
1947 			vm_page_set_valid(m, 0, nread - toff);
1948 			vm_page_clear_dirty_end_nonincl(m, 0, nread - toff);
1949 		} else {
1950 			m->valid = 0;
1951 			vm_page_undirty(m);
1952 		}
1953 
1954 		if (i != ap->a_reqpage) {
1955 			/*
1956 			 * Just in case someone was asking for this page we
1957 			 * now tell them that it is ok to use.
1958 			 */
1959 			if (!error || (m->valid == VM_PAGE_BITS_ALL)) {
1960 				if (m->valid) {
1961 					if (m->flags & PG_WANTED) {
1962 						vm_page_activate(m);
1963 					} else {
1964 						vm_page_deactivate(m);
1965 					}
1966 					vm_page_wakeup(m);
1967 				} else {
1968 					vm_page_free(m);
1969 				}
1970 			} else {
1971 				vm_page_free(m);
1972 			}
1973 		} else if (m->valid) {
1974 			gotreqpage = 1;
1975 			/*
1976 			 * Since this is a VM request, we need to make the
1977 			 * entire page presentable by zeroing invalid sections.
1978 			 */
1979 			if (m->valid != VM_PAGE_BITS_ALL)
1980 			    vm_page_zero_invalid(m, FALSE);
1981 		}
1982 	}
1983 	if (!gotreqpage) {
1984 		m = ap->a_m[ap->a_reqpage];
1985 		devfs_debug(DEVFS_DEBUG_WARNING,
1986 	    "spec_getpages:(%s) I/O read failure: (error=%d) bp %p vp %p\n",
1987 			devtoname(vp->v_rdev), error, bp, bp->b_vp);
1988 		devfs_debug(DEVFS_DEBUG_WARNING,
1989 	    "               size: %d, resid: %d, a_count: %d, valid: 0x%x\n",
1990 		    size, bp->b_resid, ap->a_count, m->valid);
1991 		devfs_debug(DEVFS_DEBUG_WARNING,
1992 	    "               nread: %d, reqpage: %d, pindex: %lu, pcount: %d\n",
1993 		    nread, ap->a_reqpage, (u_long)m->pindex, pcount);
1994 		/*
1995 		 * Free the buffer header back to the swap buffer pool.
1996 		 */
1997 		relpbuf(bp, NULL);
1998 		return VM_PAGER_ERROR;
1999 	}
2000 	/*
2001 	 * Free the buffer header back to the swap buffer pool.
2002 	 */
2003 	relpbuf(bp, NULL);
2004 	if (DEVFS_NODE(ap->a_vp))
2005 		nanotime(&DEVFS_NODE(ap->a_vp)->mtime);
2006 	return VM_PAGER_OK;
2007 }
2008 
2009 static __inline
2010 int
2011 sequential_heuristic(struct uio *uio, struct file *fp)
2012 {
2013 	/*
2014 	 * Sequential heuristic - detect sequential operation
2015 	 */
2016 	if ((uio->uio_offset == 0 && fp->f_seqcount > 0) ||
2017 	    uio->uio_offset == fp->f_nextoff) {
2018 		/*
2019 		 * XXX we assume that the filesystem block size is
2020 		 * the default.  Not true, but still gives us a pretty
2021 		 * good indicator of how sequential the read operations
2022 		 * are.
2023 		 */
2024 		int tmpseq = fp->f_seqcount;
2025 
2026 		tmpseq += (uio->uio_resid + BKVASIZE - 1) / BKVASIZE;
2027 		if (tmpseq > IO_SEQMAX)
2028 			tmpseq = IO_SEQMAX;
2029 		fp->f_seqcount = tmpseq;
2030 		return(fp->f_seqcount << IO_SEQSHIFT);
2031 	}
2032 
2033 	/*
2034 	 * Not sequential, quick draw-down of seqcount
2035 	 */
2036 	if (fp->f_seqcount > 1)
2037 		fp->f_seqcount = 1;
2038 	else
2039 		fp->f_seqcount = 0;
2040 	return(0);
2041 }
2042