xref: /titanic_50/usr/src/uts/common/fs/ufs/ufs_filio.c (revision c77a61a72b5ecdc507d6cf104142edd371a16c84)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License, Version 1.0 only
6  * (the "License").  You may not use this file except in compliance
7  * with the License.
8  *
9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10  * or http://www.opensolaris.org/os/licensing.
11  * See the License for the specific language governing permissions
12  * and limitations under the License.
13  *
14  * When distributing Covered Code, include this CDDL HEADER in each
15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16  * If applicable, add the following below this CDDL HEADER, with the
17  * fields enclosed by brackets "[]" replaced with your own identifying
18  * information: Portions Copyright [yyyy] [name of copyright owner]
19  *
20  * CDDL HEADER END
21  */
22 /*
23  * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 #pragma ident	"%Z%%M%	%I%	%E% SMI"
28 
29 #include <sys/types.h>
30 #include <sys/t_lock.h>
31 #include <sys/param.h>
32 #include <sys/time.h>
33 #include <sys/systm.h>
34 #include <sys/sysmacros.h>
35 #include <sys/resource.h>
36 #include <sys/signal.h>
37 #include <sys/cred.h>
38 #include <sys/user.h>
39 #include <sys/buf.h>
40 #include <sys/vfs.h>
41 #include <sys/vnode.h>
42 #include <sys/proc.h>
43 #include <sys/disp.h>
44 #include <sys/file.h>
45 #include <sys/fcntl.h>
46 #include <sys/flock.h>
47 #include <sys/atomic.h>
48 #include <sys/kmem.h>
49 #include <sys/uio.h>
50 #include <sys/conf.h>
51 #include <sys/mman.h>
52 #include <sys/pathname.h>
53 #include <sys/debug.h>
54 #include <sys/vmmeter.h>
55 #include <sys/vmsystm.h>
56 #include <sys/cmn_err.h>
57 #include <sys/vtrace.h>
58 #include <sys/filio.h>
59 #include <sys/dnlc.h>
60 
61 #include <sys/fs/ufs_filio.h>
62 #include <sys/fs/ufs_lockfs.h>
63 #include <sys/fs/ufs_fs.h>
64 #include <sys/fs/ufs_inode.h>
65 #include <sys/fs/ufs_fsdir.h>
66 #include <sys/fs/ufs_quota.h>
67 #include <sys/fs/ufs_trans.h>
68 #include <sys/fs/ufs_log.h>
69 #include <sys/dirent.h>		/* must be AFTER <sys/fs/fsdir.h>! */
70 #include <sys/errno.h>
71 #include <sys/sysinfo.h>
72 
73 #include <vm/hat.h>
74 #include <vm/page.h>
75 #include <vm/pvn.h>
76 #include <vm/as.h>
77 #include <vm/seg.h>
78 #include <vm/seg_map.h>
79 #include <vm/seg_vn.h>
80 #include <vm/rm.h>
81 #include <sys/swap.h>
82 #include <sys/model.h>
83 #include <sys/policy.h>
84 
85 #include "fs/fs_subr.h"
86 
87 /*
88  * ufs_fioio is the ufs equivalent of NFS_CNVT and is tailored to
89  * metamucil's needs.  It may change at any time.
90  */
91 /* ARGSUSED */
92 int
93 ufs_fioio(
94 	struct vnode	*vp,		/* any file on the fs */
95 	struct fioio	*fiou,		/* fioio struct in userland */
96 	int		flag,		/* flag from VOP_IOCTL() */
97 	struct cred	*cr)		/* credentials from ufs_ioctl */
98 {
99 	int		error	= 0;
100 	struct vnode	*vpio	= NULL;	/* vnode for inode open */
101 	struct inode	*ipio	= NULL;	/* inode for inode open */
102 	struct file	*fpio	= NULL;	/* file  for inode open */
103 	struct inode	*ip;		/* inode for file system */
104 	struct fs	*fs;		/* fs    for file system */
105 	STRUCT_DECL(fioio, fio);	/* copy of user's fioio struct */
106 
107 	/*
108 	 * must be privileged
109 	 */
110 	if (secpolicy_fs_config(cr, vp->v_vfsp) != 0)
111 		return (EPERM);
112 
113 	STRUCT_INIT(fio, flag & DATAMODEL_MASK);
114 
115 	/*
116 	 * get user's copy of fioio struct
117 	 */
118 	if (copyin(fiou, STRUCT_BUF(fio), STRUCT_SIZE(fio)))
119 		return (EFAULT);
120 
121 	ip = VTOI(vp);
122 	fs = ip->i_fs;
123 
124 	/*
125 	 * check the inode number against the fs's inode number bounds
126 	 */
127 	if (STRUCT_FGET(fio, fio_ino) < UFSROOTINO)
128 		return (ESRCH);
129 	if (STRUCT_FGET(fio, fio_ino) >= fs->fs_ncg * fs->fs_ipg)
130 		return (ESRCH);
131 
132 	rw_enter(&ip->i_ufsvfs->vfs_dqrwlock, RW_READER);
133 
134 	/*
135 	 * get the inode
136 	 */
137 	error = ufs_iget(ip->i_vfs, STRUCT_FGET(fio, fio_ino), &ipio, cr);
138 
139 	rw_exit(&ip->i_ufsvfs->vfs_dqrwlock);
140 
141 	if (error)
142 		return (error);
143 
144 	/*
145 	 * check the generation number
146 	 */
147 	rw_enter(&ipio->i_contents, RW_READER);
148 	if (ipio->i_gen != STRUCT_FGET(fio, fio_gen)) {
149 		error = ESTALE;
150 		rw_exit(&ipio->i_contents);
151 		goto errout;
152 	}
153 
154 	/*
155 	 * check if the inode is free
156 	 */
157 	if (ipio->i_mode == 0) {
158 		error = ENOENT;
159 		rw_exit(&ipio->i_contents);
160 		goto errout;
161 	}
162 	rw_exit(&ipio->i_contents);
163 
164 	/*
165 	 *	Adapted from copen: get a file struct
166 	 *	Large Files: We open this file descriptor with FOFFMAX flag
167 	 *	set so that it will be like a large file open.
168 	 */
169 	if (falloc(NULL, (FREAD|FOFFMAX), &fpio, STRUCT_FADDR(fio, fio_fd)))
170 		goto errout;
171 
172 	/*
173 	 *	Adapted from vn_open: check access and then open the file
174 	 */
175 	vpio = ITOV(ipio);
176 	if (error = VOP_ACCESS(vpio, VREAD, 0, cr))
177 		goto errout;
178 
179 	if (error = VOP_OPEN(&vpio, FREAD, cr))
180 		goto errout;
181 
182 	/*
183 	 *	Adapted from copen: initialize the file struct
184 	 */
185 	fpio->f_vnode = vpio;
186 
187 	/*
188 	 * return the fd
189 	 */
190 	if (copyout(STRUCT_BUF(fio), fiou, STRUCT_SIZE(fio))) {
191 		error = EFAULT;
192 		goto errout;
193 	}
194 	setf(STRUCT_FGET(fio, fio_fd), fpio);
195 	mutex_exit(&fpio->f_tlock);
196 	return (0);
197 errout:
198 	/*
199 	 * free the file struct and fd
200 	 */
201 	if (fpio) {
202 		setf(STRUCT_FGET(fio, fio_fd), NULL);
203 		unfalloc(fpio);
204 	}
205 
206 	/*
207 	 * release the hold on the inode
208 	 */
209 	if (ipio)
210 		VN_RELE(ITOV(ipio));
211 	return (error);
212 }
213 
214 /*
215  * ufs_fiosatime
216  *	set access time w/o altering change time.  This ioctl is tailored
217  *	to metamucil's needs and may change at any time.
218  */
219 int
220 ufs_fiosatime(
221 	struct vnode	*vp,		/* file's vnode */
222 	struct timeval	*tvu,		/* struct timeval in userland */
223 	int		flag,		/* flag from VOP_IOCTL() */
224 	struct cred	*cr)		/* credentials from ufs_ioctl */
225 {
226 	struct inode	*ip;		/* inode for vp */
227 	struct timeval32 tv;		/* copy of user's timeval */
228 	int now = 0;
229 
230 	/*
231 	 * must have sufficient privileges
232 	 */
233 	if (secpolicy_fs_config(cr, vp->v_vfsp) != 0)
234 		return (EPERM);
235 
236 	/*
237 	 * get user's copy of timeval struct and check values
238 	 * if input is NULL, will set time to now
239 	 */
240 	if (tvu == NULL) {
241 		now = 1;
242 	} else {
243 		if ((flag & DATAMODEL_MASK) == DATAMODEL_ILP32) {
244 			if (copyin(tvu, &tv, sizeof (tv)))
245 				return (EFAULT);
246 		} else {
247 			struct timeval tv64;
248 
249 			if (copyin(tvu, &tv64, sizeof (tv64)))
250 				return (EFAULT);
251 			if (TIMEVAL_OVERFLOW(&tv64))
252 				return (EOVERFLOW);
253 			TIMEVAL_TO_TIMEVAL32(&tv, &tv64);
254 		}
255 
256 		if (tv.tv_usec < 0 || tv.tv_usec >= 1000000)
257 			return (EINVAL);
258 	}
259 
260 	/*
261 	 * update access time
262 	 */
263 	ip = VTOI(vp);
264 	rw_enter(&ip->i_contents, RW_WRITER);
265 	ITIMES_NOLOCK(ip);
266 	if (now) {
267 		mutex_enter(&ufs_iuniqtime_lock);
268 		ip->i_atime = iuniqtime;
269 		mutex_exit(&ufs_iuniqtime_lock);
270 	} else {
271 		ip->i_atime = tv;
272 	}
273 	ip->i_flag |= IMODACC;
274 	rw_exit(&ip->i_contents);
275 
276 	return (0);
277 }
278 
279 /*
280  * ufs_fiogdio
281  *	Get delayed-io state.  This ioctl is tailored
282  *	to metamucil's needs and may change at any time.
283  */
284 /* ARGSUSED */
285 int
286 ufs_fiogdio(
287 	struct vnode	*vp,		/* file's vnode */
288 	uint_t		*diop,		/* dio state returned here */
289 	int		flag,		/* flag from ufs_ioctl */
290 	struct cred	*cr)		/* credentials from ufs_ioctl */
291 {
292 	struct ufsvfs	*ufsvfsp	= VTOI(vp)->i_ufsvfs;
293 
294 	/*
295 	 * forcibly unmounted
296 	 */
297 	if (ufsvfsp == NULL)
298 		return (EIO);
299 
300 	if (suword32(diop, ufsvfsp->vfs_dio))
301 		return (EFAULT);
302 	return (0);
303 }
304 
305 /*
306  * ufs_fiosdio
307  *	Set delayed-io state.  This ioctl is tailored
308  *	to metamucil's needs and may change at any time.
309  */
310 int
311 ufs_fiosdio(
312 	struct vnode	*vp,		/* file's vnode */
313 	uint_t		*diop,		/* dio flag */
314 	int		flag,		/* flag from ufs_ioctl */
315 	struct cred	*cr)		/* credentials from ufs_ioctl */
316 {
317 	uint_t		dio;		/* copy of user's dio */
318 	struct inode	*ip;		/* inode for vp */
319 	struct ufsvfs	*ufsvfsp;
320 	struct fs	*fs;
321 	struct ulockfs	*ulp;
322 	int		error = 0;
323 
324 #ifdef lint
325 	flag = flag;
326 #endif
327 
328 	/* check input conditions */
329 	if (secpolicy_fs_config(cr, vp->v_vfsp) != 0)
330 		return (EPERM);
331 
332 	if (copyin(diop, &dio, sizeof (dio)))
333 		return (EFAULT);
334 
335 	if (dio > 1)
336 		return (EINVAL);
337 
338 	/* file system has been forcibly unmounted */
339 	if (VTOI(vp)->i_ufsvfs == NULL)
340 		return (EIO);
341 
342 	ip = VTOI(vp);
343 	ufsvfsp = ip->i_ufsvfs;
344 	ulp = &ufsvfsp->vfs_ulockfs;
345 
346 	/* logging file system; dio ignored */
347 	if (TRANS_ISTRANS(ufsvfsp))
348 		return (error);
349 
350 	/* hold the mutex to prevent race with a lockfs request */
351 	vfs_lock_wait(vp->v_vfsp);
352 	mutex_enter(&ulp->ul_lock);
353 	atomic_add_long(&ufs_quiesce_pend, 1);
354 
355 	if (ULOCKFS_IS_HLOCK(ulp)) {
356 		error = EIO;
357 		goto out;
358 	}
359 
360 	if (ULOCKFS_IS_ELOCK(ulp)) {
361 		error = EBUSY;
362 		goto out;
363 	}
364 	/* wait for outstanding accesses to finish */
365 	if (error = ufs_quiesce(ulp))
366 		goto out;
367 
368 	/* flush w/invalidate */
369 	if (error = ufs_flush(vp->v_vfsp))
370 		goto out;
371 
372 	/*
373 	 * update dio
374 	 */
375 	mutex_enter(&ufsvfsp->vfs_lock);
376 	ufsvfsp->vfs_dio = dio;
377 
378 	/*
379 	 * enable/disable clean flag processing
380 	 */
381 	fs = ip->i_fs;
382 	if (fs->fs_ronly == 0 &&
383 	    fs->fs_clean != FSBAD &&
384 	    fs->fs_clean != FSLOG) {
385 		if (dio)
386 			fs->fs_clean = FSSUSPEND;
387 		else
388 			fs->fs_clean = FSACTIVE;
389 		ufs_sbwrite(ufsvfsp);
390 		mutex_exit(&ufsvfsp->vfs_lock);
391 	} else
392 		mutex_exit(&ufsvfsp->vfs_lock);
393 out:
394 	/*
395 	 * we need this broadcast because of the ufs_quiesce call above
396 	 */
397 	atomic_add_long(&ufs_quiesce_pend, -1);
398 	cv_broadcast(&ulp->ul_cv);
399 	mutex_exit(&ulp->ul_lock);
400 	vfs_unlock(vp->v_vfsp);
401 	return (error);
402 }
403 
404 /*
405  * ufs_fioffs - ioctl handler for flushing file system
406  */
407 /* ARGSUSED */
408 int
409 ufs_fioffs(
410 	struct vnode	*vp,
411 	char 		*vap,		/* must be NULL - reserved */
412 	struct cred	*cr)		/* credentials from ufs_ioctl */
413 {
414 	int error;
415 	struct ufsvfs	*ufsvfsp;
416 	struct ulockfs	*ulp;
417 
418 	/* file system has been forcibly unmounted */
419 	ufsvfsp = VTOI(vp)->i_ufsvfs;
420 	if (ufsvfsp == NULL)
421 		return (EIO);
422 
423 	ulp = &ufsvfsp->vfs_ulockfs;
424 
425 	/*
426 	 * suspend the delete thread
427 	 *	this must be done outside the lockfs locking protocol
428 	 */
429 	ufs_thread_suspend(&ufsvfsp->vfs_delete);
430 
431 	vfs_lock_wait(vp->v_vfsp);
432 	/* hold the mutex to prevent race with a lockfs request */
433 	mutex_enter(&ulp->ul_lock);
434 	atomic_add_long(&ufs_quiesce_pend, 1);
435 
436 	if (ULOCKFS_IS_HLOCK(ulp)) {
437 		error = EIO;
438 		goto out;
439 	}
440 	if (ULOCKFS_IS_ELOCK(ulp)) {
441 		error = EBUSY;
442 		goto out;
443 	}
444 	/* wait for outstanding accesses to finish */
445 	if (error = ufs_quiesce(ulp))
446 		goto out;
447 
448 	/*
449 	 * If logging, and the logmap was marked as not rollable,
450 	 * make it rollable now, and start the trans_roll thread and
451 	 * the reclaim thread.  The log at this point is safe to write to.
452 	 */
453 	if (ufsvfsp->vfs_log) {
454 		ml_unit_t	*ul = ufsvfsp->vfs_log;
455 		struct fs	*fsp = ufsvfsp->vfs_fs;
456 		int		err;
457 
458 		if (ul->un_flags & LDL_NOROLL) {
459 			ul->un_flags &= ~LDL_NOROLL;
460 			logmap_start_roll(ul);
461 			if (!fsp->fs_ronly && (fsp->fs_reclaim &
462 				(FS_RECLAIM|FS_RECLAIMING))) {
463 				fsp->fs_reclaim &= ~FS_RECLAIM;
464 				fsp->fs_reclaim |= FS_RECLAIMING;
465 				ufs_thread_start(&ufsvfsp->vfs_reclaim,
466 					ufs_thread_reclaim,
467 					vp->v_vfsp);
468 				if (!fsp->fs_ronly) {
469 					TRANS_SBWRITE(ufsvfsp,
470 						TOP_SBUPDATE_UPDATE);
471 					if (err =
472 					    geterror(ufsvfsp->vfs_bufp)) {
473 						refstr_t	*mntpt;
474 						mntpt = vfs_getmntpoint(
475 							vp->v_vfsp);
476 						cmn_err(CE_NOTE,
477 							"Filesystem Flush "
478 							"Failed to update "
479 							"Reclaim Status for "
480 							" %s, Write failed to "
481 							"update superblock, "
482 							"error %d",
483 							refstr_value(mntpt),
484 							err);
485 						refstr_rele(mntpt);
486 					}
487 				}
488 			}
489 		}
490 	}
491 
492 	/* synchronously flush dirty data and metadata */
493 	error = ufs_flush(vp->v_vfsp);
494 
495 out:
496 	atomic_add_long(&ufs_quiesce_pend, -1);
497 	cv_broadcast(&ulp->ul_cv);
498 	mutex_exit(&ulp->ul_lock);
499 	vfs_unlock(vp->v_vfsp);
500 
501 	/*
502 	 * allow the delete thread to continue
503 	 */
504 	ufs_thread_continue(&ufsvfsp->vfs_delete);
505 	return (error);
506 }
507 
508 /*
509  * ufs_fioisbusy
510  *	Get number of references on this vnode.
511  *	Contract-private interface for Legato's NetWorker product.
512  */
513 /* ARGSUSED */
514 int
515 ufs_fioisbusy(struct vnode *vp, int *isbusy, struct cred *cr)
516 {
517 	int is_it_busy;
518 
519 	/*
520 	 * The caller holds one reference, there may be one in the dnlc
521 	 * so we need to flush it.
522 	 */
523 	if (vp->v_count > 1)
524 		dnlc_purge_vp(vp);
525 	/*
526 	 * Since we've just flushed the dnlc and we hold a reference
527 	 * to this vnode, then anything but 1 means busy (this had
528 	 * BETTER not be zero!). Also, it's possible for someone to
529 	 * have this file mmap'ed with no additional reference count.
530 	 */
531 	ASSERT(vp->v_count > 0);
532 	if ((vp->v_count == 1) && (VTOI(vp)->i_mapcnt == 0))
533 		is_it_busy = 0;
534 	else
535 		is_it_busy = 1;
536 
537 	if (suword32(isbusy, is_it_busy))
538 		return (EFAULT);
539 	return (0);
540 }
541 
542 /* ARGSUSED */
543 int
544 ufs_fiodirectio(struct vnode *vp, int cmd, struct cred *cr)
545 {
546 	int		error	= 0;
547 	struct inode	*ip	= VTOI(vp);
548 
549 	/*
550 	 * Acquire reader lock and set/reset direct mode
551 	 */
552 	rw_enter(&ip->i_contents, RW_READER);
553 	mutex_enter(&ip->i_tlock);
554 	if (cmd == DIRECTIO_ON)
555 		ip->i_flag |= IDIRECTIO;	/* enable direct mode */
556 	else if (cmd == DIRECTIO_OFF)
557 		ip->i_flag &= ~IDIRECTIO;	/* disable direct mode */
558 	else
559 		error = EINVAL;
560 	mutex_exit(&ip->i_tlock);
561 	rw_exit(&ip->i_contents);
562 	return (error);
563 }
564 
565 /*
566  * ufs_fiotune
567  *	Allow some tunables to be set on a mounted fs
568  */
569 int
570 ufs_fiotune(struct vnode *vp, struct fiotune *uftp, struct cred *cr)
571 {
572 	struct fiotune	ftp;
573 	struct fs	*fs;
574 	struct ufsvfs	*ufsvfsp;
575 
576 	/*
577 	 * must have sufficient privileges
578 	 */
579 	if (secpolicy_fs_config(cr, vp->v_vfsp) != 0)
580 		return (EPERM);
581 
582 	/*
583 	 * get user's copy
584 	 */
585 	if (copyin(uftp, &ftp, sizeof (ftp)))
586 		return (EFAULT);
587 
588 	/*
589 	 * some minimal sanity checks
590 	 */
591 	if ((ftp.maxcontig <= 0) ||
592 	    (ftp.rotdelay != 0) ||
593 	    (ftp.maxbpg <= 0) ||
594 	    (ftp.minfree < 0) ||
595 	    (ftp.minfree > 99) ||
596 	    ((ftp.optim != FS_OPTTIME) && (ftp.optim != FS_OPTSPACE)))
597 		return (EINVAL);
598 
599 	/*
600 	 * update superblock but don't write it!  If it gets out, fine.
601 	 */
602 	fs = VTOI(vp)->i_fs;
603 
604 	fs->fs_maxcontig = ftp.maxcontig;
605 	fs->fs_rotdelay = ftp.rotdelay;
606 	fs->fs_maxbpg = ftp.maxbpg;
607 	fs->fs_minfree = ftp.minfree;
608 	fs->fs_optim = ftp.optim;
609 
610 	/*
611 	 * Adjust cluster based on the new maxcontig. The cluster size
612 	 * can be any positive value. The check for this is done above.
613 	 */
614 	ufsvfsp = VTOI(vp)->i_ufsvfs;
615 	ufsvfsp->vfs_ioclustsz = fs->fs_bsize * fs->fs_maxcontig;
616 
617 	/*
618 	 * Adjust minfrags from minfree
619 	 */
620 	ufsvfsp->vfs_minfrags = (int)((int64_t)fs->fs_dsize *
621 							fs->fs_minfree / 100);
622 
623 	/*
624 	 * Write the superblock
625 	 */
626 	if (fs->fs_ronly == 0) {
627 		TRANS_BEGIN_ASYNC(ufsvfsp, TOP_SBUPDATE_UPDATE,
628 		    TOP_SBWRITE_SIZE);
629 		TRANS_SBWRITE(ufsvfsp, TOP_SBUPDATE_UPDATE);
630 		TRANS_END_ASYNC(ufsvfsp, TOP_SBUPDATE_UPDATE, TOP_SBWRITE_SIZE);
631 	}
632 
633 	return (0);
634 }
635 
636 /*
637  * Lseek support for finding holes (cmd == _FIO_SEEK_HOLE) and
638  * data (cmd == _FIO_SEEK_DATA). "off" is an in/out parameter.
639  */
640 int
641 ufs_fio_holey(vnode_t *vp, int cmd, offset_t *off)
642 {
643 	inode_t	*ip = VTOI(vp);
644 	u_offset_t noff = (u_offset_t)*off; /* new offset */
645 	u_offset_t isz;
646 	int error;
647 	boolean_t hole;
648 
649 	rw_enter(&ip->i_contents, RW_READER);
650 	isz = ip->i_size;
651 	if (noff >= isz)  {
652 		rw_exit(&ip->i_contents);
653 		return (ENXIO);
654 	}
655 
656 	/*
657 	 * Check for the usual case where a file has no holes.
658 	 * If so we can optimise to set the end of the file as the first
659 	 * (virtual) hole. This avoids bmap_find() searching through
660 	 * every block in the file for a (non-existent) hole.
661 	 */
662 	if (!bmap_has_holes(ip)) {
663 		rw_exit(&ip->i_contents);
664 		if (cmd == _FIO_SEEK_HOLE) {
665 			*off = isz;
666 			return (0);
667 		}
668 		/* *off must already point to valid data (non hole) */
669 		return (0);
670 	}
671 
672 	/*
673 	 * Calling bmap_read() one block at a time on a 1TB file takes forever,
674 	 * so we use a special function to search for holes or blocks.
675 	 */
676 	if (cmd == _FIO_SEEK_HOLE)
677 		hole = B_TRUE;
678 	else
679 		hole = B_FALSE;
680 	error = bmap_find(ip, hole, &noff);
681 	rw_exit(&ip->i_contents);
682 
683 	/* end of file? */
684 	if (error == ENXIO) {
685 		/*
686 		 * Handle the virtual hole at the end of file.
687 		 */
688 		if (cmd == _FIO_SEEK_HOLE) {
689 			*off = isz;
690 			return (0);
691 		}
692 		return (ENXIO);
693 	}
694 	if (noff < *off)
695 		return (error);
696 	*off = noff;
697 	return (error);
698 }
699