xref: /freebsd/sys/ufs/ffs/ffs_inode.c (revision e4e9813eb92cd7c4d4b819a8fbed5cbd3d92f5d8)
1 /*-
2  * Copyright (c) 1982, 1986, 1989, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 4. Neither the name of the University nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  *
29  *	@(#)ffs_inode.c	8.13 (Berkeley) 4/21/95
30  */
31 
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
34 
35 #include "opt_quota.h"
36 
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/mount.h>
40 #include <sys/proc.h>
41 #include <sys/bio.h>
42 #include <sys/buf.h>
43 #include <sys/vnode.h>
44 #include <sys/malloc.h>
45 #include <sys/resourcevar.h>
46 #include <sys/vmmeter.h>
47 #include <sys/stat.h>
48 
49 #include <vm/vm.h>
50 #include <vm/vm_extern.h>
51 
52 #include <ufs/ufs/extattr.h>
53 #include <ufs/ufs/quota.h>
54 #include <ufs/ufs/ufsmount.h>
55 #include <ufs/ufs/inode.h>
56 #include <ufs/ufs/ufs_extern.h>
57 
58 #include <ufs/ffs/fs.h>
59 #include <ufs/ffs/ffs_extern.h>
60 
61 static int ffs_indirtrunc(struct inode *, ufs2_daddr_t, ufs2_daddr_t,
62 	    ufs2_daddr_t, int, ufs2_daddr_t *);
63 
64 /*
65  * Update the access, modified, and inode change times as specified by the
66  * IN_ACCESS, IN_UPDATE, and IN_CHANGE flags respectively.  Write the inode
67  * to disk if the IN_MODIFIED flag is set (it may be set initially, or by
68  * the timestamp update).  The IN_LAZYMOD flag is set to force a write
69  * later if not now.  If we write now, then clear both IN_MODIFIED and
70  * IN_LAZYMOD to reflect the presumably successful write, and if waitfor is
71  * set, then wait for the write to complete.
72  */
73 int
74 ffs_update(vp, waitfor)
75 	struct vnode *vp;
76 	int waitfor;
77 {
78 	struct fs *fs;
79 	struct buf *bp;
80 	struct inode *ip;
81 	int error;
82 
83 	ASSERT_VOP_LOCKED(vp, "ffs_update");
84 	ufs_itimes(vp);
85 	ip = VTOI(vp);
86 	if ((ip->i_flag & IN_MODIFIED) == 0 && waitfor == 0)
87 		return (0);
88 	ip->i_flag &= ~(IN_LAZYMOD | IN_MODIFIED);
89 	fs = ip->i_fs;
90 	if (fs->fs_ronly)
91 		return (0);
92 	/*
93 	 * Ensure that uid and gid are correct. This is a temporary
94 	 * fix until fsck has been changed to do the update.
95 	 */
96 	if (fs->fs_magic == FS_UFS1_MAGIC &&		/* XXX */
97 	    fs->fs_old_inodefmt < FS_44INODEFMT) {	/* XXX */
98 		ip->i_din1->di_ouid = ip->i_uid;	/* XXX */
99 		ip->i_din1->di_ogid = ip->i_gid;	/* XXX */
100 	}						/* XXX */
101 	error = bread(ip->i_devvp, fsbtodb(fs, ino_to_fsba(fs, ip->i_number)),
102 		(int)fs->fs_bsize, NOCRED, &bp);
103 	if (error) {
104 		brelse(bp);
105 		return (error);
106 	}
107 	if (DOINGSOFTDEP(vp))
108 		softdep_update_inodeblock(ip, bp, waitfor);
109 	else if (ip->i_effnlink != ip->i_nlink)
110 		panic("ffs_update: bad link cnt");
111 	if (ip->i_ump->um_fstype == UFS1)
112 		*((struct ufs1_dinode *)bp->b_data +
113 		    ino_to_fsbo(fs, ip->i_number)) = *ip->i_din1;
114 	else
115 		*((struct ufs2_dinode *)bp->b_data +
116 		    ino_to_fsbo(fs, ip->i_number)) = *ip->i_din2;
117 	if (waitfor && !DOINGASYNC(vp)) {
118 		return (bwrite(bp));
119 	} else if (vm_page_count_severe() || buf_dirty_count_severe()) {
120 		return (bwrite(bp));
121 	} else {
122 		if (bp->b_bufsize == fs->fs_bsize)
123 			bp->b_flags |= B_CLUSTEROK;
124 		bdwrite(bp);
125 		return (0);
126 	}
127 }
128 
129 #define	SINGLE	0	/* index of single indirect block */
130 #define	DOUBLE	1	/* index of double indirect block */
131 #define	TRIPLE	2	/* index of triple indirect block */
132 /*
133  * Truncate the inode ip to at most length size, freeing the
134  * disk blocks.
135  */
136 int
137 ffs_truncate(vp, length, flags, cred, td)
138 	struct vnode *vp;
139 	off_t length;
140 	int flags;
141 	struct ucred *cred;
142 	struct thread *td;
143 {
144 	struct inode *ip;
145 	ufs2_daddr_t bn, lbn, lastblock, lastiblock[NIADDR], indir_lbn[NIADDR];
146 	ufs2_daddr_t oldblks[NDADDR + NIADDR], newblks[NDADDR + NIADDR];
147 	ufs2_daddr_t count, blocksreleased = 0, datablocks;
148 	struct fs *fs;
149 	struct buf *bp;
150 	struct ufsmount *ump;
151 	int needextclean, softdepslowdown, extblocks;
152 	int offset, size, level, nblocks;
153 	int i, error, allerror;
154 	off_t osize;
155 
156 	ip = VTOI(vp);
157 	fs = ip->i_fs;
158 	ump = ip->i_ump;
159 
160 	ASSERT_VOP_LOCKED(vp, "ffs_truncate");
161 
162 	if (length < 0)
163 		return (EINVAL);
164 	/*
165 	 * Historically clients did not have to specify which data
166 	 * they were truncating. So, if not specified, we assume
167 	 * traditional behavior, e.g., just the normal data.
168 	 */
169 	if ((flags & (IO_EXT | IO_NORMAL)) == 0)
170 		flags |= IO_NORMAL;
171 	/*
172 	 * If we are truncating the extended-attributes, and cannot
173 	 * do it with soft updates, then do it slowly here. If we are
174 	 * truncating both the extended attributes and the file contents
175 	 * (e.g., the file is being unlinked), then pick it off with
176 	 * soft updates below.
177 	 */
178 	needextclean = 0;
179 	softdepslowdown = DOINGSOFTDEP(vp) && softdep_slowdown(vp);
180 	extblocks = 0;
181 	datablocks = DIP(ip, i_blocks);
182 	if (fs->fs_magic == FS_UFS2_MAGIC && ip->i_din2->di_extsize > 0) {
183 		extblocks = btodb(fragroundup(fs, ip->i_din2->di_extsize));
184 		datablocks -= extblocks;
185 	}
186 	if ((flags & IO_EXT) && extblocks > 0) {
187 		if (DOINGSOFTDEP(vp) && softdepslowdown == 0 && length == 0) {
188 			if ((flags & IO_NORMAL) == 0) {
189 				softdep_setup_freeblocks(ip, length, IO_EXT);
190 				return (0);
191 			}
192 			needextclean = 1;
193 		} else {
194 			if (length != 0)
195 				panic("ffs_truncate: partial trunc of extdata");
196 			if ((error = ffs_syncvnode(vp, MNT_WAIT)) != 0)
197 				return (error);
198 			osize = ip->i_din2->di_extsize;
199 			ip->i_din2->di_blocks -= extblocks;
200 #ifdef QUOTA
201 			(void) chkdq(ip, -extblocks, NOCRED, 0);
202 #endif
203 			vinvalbuf(vp, V_ALT, td, 0, 0);
204 			ip->i_din2->di_extsize = 0;
205 			for (i = 0; i < NXADDR; i++) {
206 				oldblks[i] = ip->i_din2->di_extb[i];
207 				ip->i_din2->di_extb[i] = 0;
208 			}
209 			ip->i_flag |= IN_CHANGE | IN_UPDATE;
210 			if ((error = ffs_update(vp, 1)))
211 				return (error);
212 			for (i = 0; i < NXADDR; i++) {
213 				if (oldblks[i] == 0)
214 					continue;
215 				ffs_blkfree(ump, fs, ip->i_devvp, oldblks[i],
216 				    sblksize(fs, osize, i), ip->i_number);
217 			}
218 		}
219 	}
220 	if ((flags & IO_NORMAL) == 0)
221 		return (0);
222 	if (length > fs->fs_maxfilesize)
223 		return (EFBIG);
224 	if (vp->v_type == VLNK &&
225 	    (ip->i_size < vp->v_mount->mnt_maxsymlinklen ||
226 	     datablocks == 0)) {
227 #ifdef DIAGNOSTIC
228 		if (length != 0)
229 			panic("ffs_truncate: partial truncate of symlink");
230 #endif
231 		bzero(SHORTLINK(ip), (u_int)ip->i_size);
232 		ip->i_size = 0;
233 		DIP_SET(ip, i_size, 0);
234 		ip->i_flag |= IN_CHANGE | IN_UPDATE;
235 		if (needextclean)
236 			softdep_setup_freeblocks(ip, length, IO_EXT);
237 		return (ffs_update(vp, 1));
238 	}
239 	if (ip->i_size == length) {
240 		ip->i_flag |= IN_CHANGE | IN_UPDATE;
241 		if (needextclean)
242 			softdep_setup_freeblocks(ip, length, IO_EXT);
243 		return (ffs_update(vp, 0));
244 	}
245 	if (fs->fs_ronly)
246 		panic("ffs_truncate: read-only filesystem");
247 #ifdef QUOTA
248 	error = getinoquota(ip);
249 	if (error)
250 		return (error);
251 #endif
252 	if ((ip->i_flags & SF_SNAPSHOT) != 0)
253 		ffs_snapremove(vp);
254 	vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0;
255 	if (DOINGSOFTDEP(vp)) {
256 		if (length > 0 || softdepslowdown) {
257 			/*
258 			 * If a file is only partially truncated, then
259 			 * we have to clean up the data structures
260 			 * describing the allocation past the truncation
261 			 * point. Finding and deallocating those structures
262 			 * is a lot of work. Since partial truncation occurs
263 			 * rarely, we solve the problem by syncing the file
264 			 * so that it will have no data structures left.
265 			 */
266 			if ((error = ffs_syncvnode(vp, MNT_WAIT)) != 0)
267 				return (error);
268 			UFS_LOCK(ump);
269 			if (ip->i_flag & IN_SPACECOUNTED)
270 				fs->fs_pendingblocks -= datablocks;
271 			UFS_UNLOCK(ump);
272 		} else {
273 #ifdef QUOTA
274 			(void) chkdq(ip, -datablocks, NOCRED, 0);
275 #endif
276 			softdep_setup_freeblocks(ip, length, needextclean ?
277 			    IO_EXT | IO_NORMAL : IO_NORMAL);
278 			ASSERT_VOP_LOCKED(vp, "ffs_truncate1");
279 			vinvalbuf(vp, needextclean ? 0 : V_NORMAL, td, 0, 0);
280 			vnode_pager_setsize(vp, 0);
281 			ip->i_flag |= IN_CHANGE | IN_UPDATE;
282 			return (ffs_update(vp, 0));
283 		}
284 	}
285 	osize = ip->i_size;
286 	/*
287 	 * Lengthen the size of the file. We must ensure that the
288 	 * last byte of the file is allocated. Since the smallest
289 	 * value of osize is 0, length will be at least 1.
290 	 */
291 	if (osize < length) {
292 		vnode_pager_setsize(vp, length);
293 		flags |= BA_CLRBUF;
294 		error = UFS_BALLOC(vp, length - 1, 1, cred, flags, &bp);
295 		if (error)
296 			return (error);
297 		ip->i_size = length;
298 		DIP_SET(ip, i_size, length);
299 		if (bp->b_bufsize == fs->fs_bsize)
300 			bp->b_flags |= B_CLUSTEROK;
301 		if (flags & IO_SYNC)
302 			bwrite(bp);
303 		else
304 			bawrite(bp);
305 		ip->i_flag |= IN_CHANGE | IN_UPDATE;
306 		return (ffs_update(vp, 1));
307 	}
308 	/*
309 	 * Shorten the size of the file. If the file is not being
310 	 * truncated to a block boundary, the contents of the
311 	 * partial block following the end of the file must be
312 	 * zero'ed in case it ever becomes accessible again because
313 	 * of subsequent file growth. Directories however are not
314 	 * zero'ed as they should grow back initialized to empty.
315 	 */
316 	offset = blkoff(fs, length);
317 	if (offset == 0) {
318 		ip->i_size = length;
319 		DIP_SET(ip, i_size, length);
320 	} else {
321 		lbn = lblkno(fs, length);
322 		flags |= BA_CLRBUF;
323 		error = UFS_BALLOC(vp, length - 1, 1, cred, flags, &bp);
324 		if (error) {
325 			return (error);
326 		}
327 		/*
328 		 * When we are doing soft updates and the UFS_BALLOC
329 		 * above fills in a direct block hole with a full sized
330 		 * block that will be truncated down to a fragment below,
331 		 * we must flush out the block dependency with an FSYNC
332 		 * so that we do not get a soft updates inconsistency
333 		 * when we create the fragment below.
334 		 */
335 		if (DOINGSOFTDEP(vp) && lbn < NDADDR &&
336 		    fragroundup(fs, blkoff(fs, length)) < fs->fs_bsize &&
337 		    (error = ffs_syncvnode(vp, MNT_WAIT)) != 0)
338 			return (error);
339 		ip->i_size = length;
340 		DIP_SET(ip, i_size, length);
341 		size = blksize(fs, ip, lbn);
342 		if (vp->v_type != VDIR)
343 			bzero((char *)bp->b_data + offset,
344 			    (u_int)(size - offset));
345 		/* Kirk's code has reallocbuf(bp, size, 1) here */
346 		allocbuf(bp, size);
347 		if (bp->b_bufsize == fs->fs_bsize)
348 			bp->b_flags |= B_CLUSTEROK;
349 		if (flags & IO_SYNC)
350 			bwrite(bp);
351 		else
352 			bawrite(bp);
353 	}
354 	/*
355 	 * Calculate index into inode's block list of
356 	 * last direct and indirect blocks (if any)
357 	 * which we want to keep.  Lastblock is -1 when
358 	 * the file is truncated to 0.
359 	 */
360 	lastblock = lblkno(fs, length + fs->fs_bsize - 1) - 1;
361 	lastiblock[SINGLE] = lastblock - NDADDR;
362 	lastiblock[DOUBLE] = lastiblock[SINGLE] - NINDIR(fs);
363 	lastiblock[TRIPLE] = lastiblock[DOUBLE] - NINDIR(fs) * NINDIR(fs);
364 	nblocks = btodb(fs->fs_bsize);
365 	/*
366 	 * Update file and block pointers on disk before we start freeing
367 	 * blocks.  If we crash before free'ing blocks below, the blocks
368 	 * will be returned to the free list.  lastiblock values are also
369 	 * normalized to -1 for calls to ffs_indirtrunc below.
370 	 */
371 	for (level = TRIPLE; level >= SINGLE; level--) {
372 		oldblks[NDADDR + level] = DIP(ip, i_ib[level]);
373 		if (lastiblock[level] < 0) {
374 			DIP_SET(ip, i_ib[level], 0);
375 			lastiblock[level] = -1;
376 		}
377 	}
378 	for (i = 0; i < NDADDR; i++) {
379 		oldblks[i] = DIP(ip, i_db[i]);
380 		if (i > lastblock)
381 			DIP_SET(ip, i_db[i], 0);
382 	}
383 	ip->i_flag |= IN_CHANGE | IN_UPDATE;
384 	allerror = ffs_update(vp, 1);
385 
386 	/*
387 	 * Having written the new inode to disk, save its new configuration
388 	 * and put back the old block pointers long enough to process them.
389 	 * Note that we save the new block configuration so we can check it
390 	 * when we are done.
391 	 */
392 	for (i = 0; i < NDADDR; i++) {
393 		newblks[i] = DIP(ip, i_db[i]);
394 		DIP_SET(ip, i_db[i], oldblks[i]);
395 	}
396 	for (i = 0; i < NIADDR; i++) {
397 		newblks[NDADDR + i] = DIP(ip, i_ib[i]);
398 		DIP_SET(ip, i_ib[i], oldblks[NDADDR + i]);
399 	}
400 	ip->i_size = osize;
401 	DIP_SET(ip, i_size, osize);
402 
403 	error = vtruncbuf(vp, cred, td, length, fs->fs_bsize);
404 	if (error && (allerror == 0))
405 		allerror = error;
406 
407 	/*
408 	 * Indirect blocks first.
409 	 */
410 	indir_lbn[SINGLE] = -NDADDR;
411 	indir_lbn[DOUBLE] = indir_lbn[SINGLE] - NINDIR(fs) - 1;
412 	indir_lbn[TRIPLE] = indir_lbn[DOUBLE] - NINDIR(fs) * NINDIR(fs) - 1;
413 	for (level = TRIPLE; level >= SINGLE; level--) {
414 		bn = DIP(ip, i_ib[level]);
415 		if (bn != 0) {
416 			error = ffs_indirtrunc(ip, indir_lbn[level],
417 			    fsbtodb(fs, bn), lastiblock[level], level, &count);
418 			if (error)
419 				allerror = error;
420 			blocksreleased += count;
421 			if (lastiblock[level] < 0) {
422 				DIP_SET(ip, i_ib[level], 0);
423 				ffs_blkfree(ump, fs, ip->i_devvp, bn,
424 				    fs->fs_bsize, ip->i_number);
425 				blocksreleased += nblocks;
426 			}
427 		}
428 		if (lastiblock[level] >= 0)
429 			goto done;
430 	}
431 
432 	/*
433 	 * All whole direct blocks or frags.
434 	 */
435 	for (i = NDADDR - 1; i > lastblock; i--) {
436 		long bsize;
437 
438 		bn = DIP(ip, i_db[i]);
439 		if (bn == 0)
440 			continue;
441 		DIP_SET(ip, i_db[i], 0);
442 		bsize = blksize(fs, ip, i);
443 		ffs_blkfree(ump, fs, ip->i_devvp, bn, bsize, ip->i_number);
444 		blocksreleased += btodb(bsize);
445 	}
446 	if (lastblock < 0)
447 		goto done;
448 
449 	/*
450 	 * Finally, look for a change in size of the
451 	 * last direct block; release any frags.
452 	 */
453 	bn = DIP(ip, i_db[lastblock]);
454 	if (bn != 0) {
455 		long oldspace, newspace;
456 
457 		/*
458 		 * Calculate amount of space we're giving
459 		 * back as old block size minus new block size.
460 		 */
461 		oldspace = blksize(fs, ip, lastblock);
462 		ip->i_size = length;
463 		DIP_SET(ip, i_size, length);
464 		newspace = blksize(fs, ip, lastblock);
465 		if (newspace == 0)
466 			panic("ffs_truncate: newspace");
467 		if (oldspace - newspace > 0) {
468 			/*
469 			 * Block number of space to be free'd is
470 			 * the old block # plus the number of frags
471 			 * required for the storage we're keeping.
472 			 */
473 			bn += numfrags(fs, newspace);
474 			ffs_blkfree(ump, fs, ip->i_devvp, bn,
475 			    oldspace - newspace, ip->i_number);
476 			blocksreleased += btodb(oldspace - newspace);
477 		}
478 	}
479 done:
480 #ifdef DIAGNOSTIC
481 	for (level = SINGLE; level <= TRIPLE; level++)
482 		if (newblks[NDADDR + level] != DIP(ip, i_ib[level]))
483 			panic("ffs_truncate1");
484 	for (i = 0; i < NDADDR; i++)
485 		if (newblks[i] != DIP(ip, i_db[i]))
486 			panic("ffs_truncate2");
487 	VI_LOCK(vp);
488 	if (length == 0 &&
489 	    (fs->fs_magic != FS_UFS2_MAGIC || ip->i_din2->di_extsize == 0) &&
490 	    (vp->v_bufobj.bo_dirty.bv_cnt > 0 ||
491 	     vp->v_bufobj.bo_clean.bv_cnt > 0))
492 		panic("ffs_truncate3");
493 	VI_UNLOCK(vp);
494 #endif /* DIAGNOSTIC */
495 	/*
496 	 * Put back the real size.
497 	 */
498 	ip->i_size = length;
499 	DIP_SET(ip, i_size, length);
500 	DIP_SET(ip, i_blocks, DIP(ip, i_blocks) - blocksreleased);
501 
502 	if (DIP(ip, i_blocks) < 0)			/* sanity */
503 		DIP_SET(ip, i_blocks, 0);
504 	ip->i_flag |= IN_CHANGE;
505 #ifdef QUOTA
506 	(void) chkdq(ip, -blocksreleased, NOCRED, 0);
507 #endif
508 	return (allerror);
509 }
510 
511 /*
512  * Release blocks associated with the inode ip and stored in the indirect
513  * block bn.  Blocks are free'd in LIFO order up to (but not including)
514  * lastbn.  If level is greater than SINGLE, the block is an indirect block
515  * and recursive calls to indirtrunc must be used to cleanse other indirect
516  * blocks.
517  */
518 static int
519 ffs_indirtrunc(ip, lbn, dbn, lastbn, level, countp)
520 	struct inode *ip;
521 	ufs2_daddr_t lbn, lastbn;
522 	ufs2_daddr_t dbn;
523 	int level;
524 	ufs2_daddr_t *countp;
525 {
526 	struct buf *bp;
527 	struct fs *fs = ip->i_fs;
528 	struct vnode *vp;
529 	caddr_t copy = NULL;
530 	int i, nblocks, error = 0, allerror = 0;
531 	ufs2_daddr_t nb, nlbn, last;
532 	ufs2_daddr_t blkcount, factor, blocksreleased = 0;
533 	ufs1_daddr_t *bap1 = NULL;
534 	ufs2_daddr_t *bap2 = NULL;
535 #	define BAP(ip, i) (((ip)->i_ump->um_fstype == UFS1) ? bap1[i] : bap2[i])
536 
537 	/*
538 	 * Calculate index in current block of last
539 	 * block to be kept.  -1 indicates the entire
540 	 * block so we need not calculate the index.
541 	 */
542 	factor = 1;
543 	for (i = SINGLE; i < level; i++)
544 		factor *= NINDIR(fs);
545 	last = lastbn;
546 	if (lastbn > 0)
547 		last /= factor;
548 	nblocks = btodb(fs->fs_bsize);
549 	/*
550 	 * Get buffer of block pointers, zero those entries corresponding
551 	 * to blocks to be free'd, and update on disk copy first.  Since
552 	 * double(triple) indirect before single(double) indirect, calls
553 	 * to bmap on these blocks will fail.  However, we already have
554 	 * the on disk address, so we have to set the b_blkno field
555 	 * explicitly instead of letting bread do everything for us.
556 	 */
557 	vp = ITOV(ip);
558 	bp = getblk(vp, lbn, (int)fs->fs_bsize, 0, 0, 0);
559 	if ((bp->b_flags & B_CACHE) == 0) {
560 		curproc->p_stats->p_ru.ru_inblock++;	/* pay for read */
561 		bp->b_iocmd = BIO_READ;
562 		bp->b_flags &= ~B_INVAL;
563 		bp->b_ioflags &= ~BIO_ERROR;
564 		if (bp->b_bcount > bp->b_bufsize)
565 			panic("ffs_indirtrunc: bad buffer size");
566 		bp->b_blkno = dbn;
567 		vfs_busy_pages(bp, 0);
568 		bp->b_iooffset = dbtob(bp->b_blkno);
569 		bstrategy(bp);
570 		error = bufwait(bp);
571 	}
572 	if (error) {
573 		brelse(bp);
574 		*countp = 0;
575 		return (error);
576 	}
577 
578 	if (ip->i_ump->um_fstype == UFS1)
579 		bap1 = (ufs1_daddr_t *)bp->b_data;
580 	else
581 		bap2 = (ufs2_daddr_t *)bp->b_data;
582 	if (lastbn != -1) {
583 		MALLOC(copy, caddr_t, fs->fs_bsize, M_TEMP, M_WAITOK);
584 		bcopy((caddr_t)bp->b_data, copy, (u_int)fs->fs_bsize);
585 		for (i = last + 1; i < NINDIR(fs); i++)
586 			if (ip->i_ump->um_fstype == UFS1)
587 				bap1[i] = 0;
588 			else
589 				bap2[i] = 0;
590 		if (DOINGASYNC(vp)) {
591 			bawrite(bp);
592 		} else {
593 			error = bwrite(bp);
594 			if (error)
595 				allerror = error;
596 		}
597 		if (ip->i_ump->um_fstype == UFS1)
598 			bap1 = (ufs1_daddr_t *)copy;
599 		else
600 			bap2 = (ufs2_daddr_t *)copy;
601 	}
602 
603 	/*
604 	 * Recursively free totally unused blocks.
605 	 */
606 	for (i = NINDIR(fs) - 1, nlbn = lbn + 1 - i * factor; i > last;
607 	    i--, nlbn += factor) {
608 		nb = BAP(ip, i);
609 		if (nb == 0)
610 			continue;
611 		if (level > SINGLE) {
612 			if ((error = ffs_indirtrunc(ip, nlbn, fsbtodb(fs, nb),
613 			    (ufs2_daddr_t)-1, level - 1, &blkcount)) != 0)
614 				allerror = error;
615 			blocksreleased += blkcount;
616 		}
617 		ffs_blkfree(ip->i_ump, fs, ip->i_devvp, nb, fs->fs_bsize,
618 		    ip->i_number);
619 		blocksreleased += nblocks;
620 	}
621 
622 	/*
623 	 * Recursively free last partial block.
624 	 */
625 	if (level > SINGLE && lastbn >= 0) {
626 		last = lastbn % factor;
627 		nb = BAP(ip, i);
628 		if (nb != 0) {
629 			error = ffs_indirtrunc(ip, nlbn, fsbtodb(fs, nb),
630 			    last, level - 1, &blkcount);
631 			if (error)
632 				allerror = error;
633 			blocksreleased += blkcount;
634 		}
635 	}
636 	if (copy != NULL) {
637 		FREE(copy, M_TEMP);
638 	} else {
639 		bp->b_flags |= B_INVAL | B_NOCACHE;
640 		brelse(bp);
641 	}
642 
643 	*countp = blocksreleased;
644 	return (allerror);
645 }
646