xref: /netbsd-src/sys/ufs/ext2fs/ext2fs_alloc.c (revision da9817918ec7e88db2912a2882967c7570a83f47)
1 /*	$NetBSD: ext2fs_alloc.c,v 1.39 2009/05/07 19:26:08 elad Exp $	*/
2 
3 /*
4  * Copyright (c) 1982, 1986, 1989, 1993
5  *	The Regents of the University of California.  All rights reserved.
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  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. Neither the name of the University nor the names of its contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  *
31  *	@(#)ffs_alloc.c	8.11 (Berkeley) 10/27/94
32  *  Modified for ext2fs by Manuel Bouyer.
33  */
34 
35 /*
36  * Copyright (c) 1997 Manuel Bouyer.
37  *
38  * Redistribution and use in source and binary forms, with or without
39  * modification, are permitted provided that the following conditions
40  * are met:
41  * 1. Redistributions of source code must retain the above copyright
42  *    notice, this list of conditions and the following disclaimer.
43  * 2. Redistributions in binary form must reproduce the above copyright
44  *    notice, this list of conditions and the following disclaimer in the
45  *    documentation and/or other materials provided with the distribution.
46  * 3. All advertising materials mentioning features or use of this software
47  *    must display the following acknowledgement:
48  *	This product includes software developed by Manuel Bouyer.
49  * 4. The name of the author may not be used to endorse or promote products
50  *    derived from this software without specific prior written permission.
51  *
52  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
53  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
54  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
55  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
56  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
57  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
58  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
59  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
60  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
61  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
62  *
63  *	@(#)ffs_alloc.c	8.11 (Berkeley) 10/27/94
64  *  Modified for ext2fs by Manuel Bouyer.
65  */
66 
67 #include <sys/cdefs.h>
68 __KERNEL_RCSID(0, "$NetBSD: ext2fs_alloc.c,v 1.39 2009/05/07 19:26:08 elad Exp $");
69 
70 #include <sys/param.h>
71 #include <sys/systm.h>
72 #include <sys/buf.h>
73 #include <sys/proc.h>
74 #include <sys/vnode.h>
75 #include <sys/mount.h>
76 #include <sys/kernel.h>
77 #include <sys/syslog.h>
78 #include <sys/kauth.h>
79 
80 #include <ufs/ufs/inode.h>
81 #include <ufs/ufs/ufs_extern.h>
82 #include <ufs/ufs/ufsmount.h>
83 
84 #include <ufs/ext2fs/ext2fs.h>
85 #include <ufs/ext2fs/ext2fs_extern.h>
86 
87 u_long ext2gennumber;
88 
89 static daddr_t	ext2fs_alloccg(struct inode *, int, daddr_t, int);
90 static u_long	ext2fs_dirpref(struct m_ext2fs *);
91 static void	ext2fs_fserr(struct m_ext2fs *, u_int, const char *);
92 static u_long	ext2fs_hashalloc(struct inode *, int, long, int,
93 				   daddr_t (*)(struct inode *, int, daddr_t,
94 						   int));
95 static daddr_t	ext2fs_nodealloccg(struct inode *, int, daddr_t, int);
96 static daddr_t	ext2fs_mapsearch(struct m_ext2fs *, char *, daddr_t);
97 
98 /*
99  * Allocate a block in the file system.
100  *
101  * A preference may be optionally specified. If a preference is given
102  * the following hierarchy is used to allocate a block:
103  *   1) allocate the requested block.
104  *   2) allocate a rotationally optimal block in the same cylinder.
105  *   3) allocate a block in the same cylinder group.
106  *   4) quadradically rehash into other cylinder groups, until an
107  *	  available block is located.
108  * If no block preference is given the following hierarchy is used
109  * to allocate a block:
110  *   1) allocate a block in the cylinder group that contains the
111  *	  inode for the file.
112  *   2) quadradically rehash into other cylinder groups, until an
113  *	  available block is located.
114  */
115 int
116 ext2fs_alloc(struct inode *ip, daddr_t lbn, daddr_t bpref,
117     kauth_cred_t cred, daddr_t *bnp)
118 {
119 	struct m_ext2fs *fs;
120 	daddr_t bno;
121 	int cg;
122 
123 	*bnp = 0;
124 	fs = ip->i_e2fs;
125 #ifdef DIAGNOSTIC
126 	if (cred == NOCRED)
127 		panic("ext2fs_alloc: missing credential");
128 #endif /* DIAGNOSTIC */
129 	if (fs->e2fs.e2fs_fbcount == 0)
130 		goto nospace;
131 	if (kauth_authorize_system(cred, KAUTH_SYSTEM_FS_RESERVEDSPACE, 0, NULL,
132 	    NULL, NULL) != 0 &&
133 	    freespace(fs) <= 0)
134 		goto nospace;
135 	if (bpref >= fs->e2fs.e2fs_bcount)
136 		bpref = 0;
137 	if (bpref == 0)
138 		cg = ino_to_cg(fs, ip->i_number);
139 	else
140 		cg = dtog(fs, bpref);
141 	bno = (daddr_t)ext2fs_hashalloc(ip, cg, bpref, fs->e2fs_bsize,
142 						 ext2fs_alloccg);
143 	if (bno > 0) {
144 		ip->i_e2fs_nblock += btodb(fs->e2fs_bsize);
145 		ip->i_flag |= IN_CHANGE | IN_UPDATE;
146 		*bnp = bno;
147 		return (0);
148 	}
149 nospace:
150 	ext2fs_fserr(fs, kauth_cred_geteuid(cred), "file system full");
151 	uprintf("\n%s: write failed, file system is full\n", fs->e2fs_fsmnt);
152 	return (ENOSPC);
153 }
154 
155 /*
156  * Allocate an inode in the file system.
157  *
158  * If allocating a directory, use ext2fs_dirpref to select the inode.
159  * If allocating in a directory, the following hierarchy is followed:
160  *   1) allocate the preferred inode.
161  *   2) allocate an inode in the same cylinder group.
162  *   3) quadradically rehash into other cylinder groups, until an
163  *	  available inode is located.
164  * If no inode preference is given the following hierarchy is used
165  * to allocate an inode:
166  *   1) allocate an inode in cylinder group 0.
167  *   2) quadradically rehash into other cylinder groups, until an
168  *	  available inode is located.
169  */
170 int
171 ext2fs_valloc(struct vnode *pvp, int mode, kauth_cred_t cred,
172     struct vnode **vpp)
173 {
174 	struct inode *pip;
175 	struct m_ext2fs *fs;
176 	struct inode *ip;
177 	ino_t ino, ipref;
178 	int cg, error;
179 
180 	*vpp = NULL;
181 	pip = VTOI(pvp);
182 	fs = pip->i_e2fs;
183 	if (fs->e2fs.e2fs_ficount == 0)
184 		goto noinodes;
185 
186 	if ((mode & IFMT) == IFDIR)
187 		cg = ext2fs_dirpref(fs);
188 	else
189 		cg = ino_to_cg(fs, pip->i_number);
190 	ipref = cg * fs->e2fs.e2fs_ipg + 1;
191 	ino = (ino_t)ext2fs_hashalloc(pip, cg, (long)ipref, mode, ext2fs_nodealloccg);
192 	if (ino == 0)
193 		goto noinodes;
194 	error = VFS_VGET(pvp->v_mount, ino, vpp);
195 	if (error) {
196 		ext2fs_vfree(pvp, ino, mode);
197 		return (error);
198 	}
199 	ip = VTOI(*vpp);
200 	if (ip->i_e2fs_mode && ip->i_e2fs_nlink != 0) {
201 		printf("mode = 0%o, nlinks %d, inum = %llu, fs = %s\n",
202 		    ip->i_e2fs_mode, ip->i_e2fs_nlink,
203 		    (unsigned long long)ip->i_number, fs->e2fs_fsmnt);
204 		panic("ext2fs_valloc: dup alloc");
205 	}
206 
207 	memset(ip->i_din.e2fs_din, 0, sizeof(struct ext2fs_dinode));
208 
209 	/*
210 	 * Set up a new generation number for this inode.
211 	 */
212 	if (++ext2gennumber < time_second)
213 		ext2gennumber = time_second;
214 	ip->i_e2fs_gen = ext2gennumber;
215 	return (0);
216 noinodes:
217 	ext2fs_fserr(fs, kauth_cred_geteuid(cred), "out of inodes");
218 	uprintf("\n%s: create/symlink failed, no inodes free\n", fs->e2fs_fsmnt);
219 	return (ENOSPC);
220 }
221 
222 /*
223  * Find a cylinder to place a directory.
224  *
225  * The policy implemented by this algorithm is to select from
226  * among those cylinder groups with above the average number of
227  * free inodes, the one with the smallest number of directories.
228  */
229 static u_long
230 ext2fs_dirpref(struct m_ext2fs *fs)
231 {
232 	int cg, maxspace, mincg, avgifree;
233 
234 	avgifree = fs->e2fs.e2fs_ficount / fs->e2fs_ncg;
235 	maxspace = 0;
236 	mincg = -1;
237 	for (cg = 0; cg < fs->e2fs_ncg; cg++)
238 		if ( fs->e2fs_gd[cg].ext2bgd_nifree >= avgifree) {
239 			if (mincg == -1 || fs->e2fs_gd[cg].ext2bgd_nbfree > maxspace) {
240 				mincg = cg;
241 				maxspace = fs->e2fs_gd[cg].ext2bgd_nbfree;
242 			}
243 		}
244 	return mincg;
245 }
246 
247 /*
248  * Select the desired position for the next block in a file.  The file is
249  * logically divided into sections. The first section is composed of the
250  * direct blocks. Each additional section contains fs_maxbpg blocks.
251  *
252  * If no blocks have been allocated in the first section, the policy is to
253  * request a block in the same cylinder group as the inode that describes
254  * the file. Otherwise, the policy is to try to allocate the blocks
255  * contigously. The two fields of the ext2 inode extension (see
256  * ufs/ufs/inode.h) help this.
257  */
258 daddr_t
259 ext2fs_blkpref(struct inode *ip, daddr_t lbn, int indx,
260 		int32_t *bap /* XXX ondisk32 */)
261 {
262 	struct m_ext2fs *fs;
263 	int cg, i;
264 
265 	fs = ip->i_e2fs;
266 	/*
267 	 * if we are doing contigous lbn allocation, try to alloc blocks
268 	 * contigously on disk
269 	 */
270 
271 	if ( ip->i_e2fs_last_blk && lbn == ip->i_e2fs_last_lblk + 1) {
272 		return ip->i_e2fs_last_blk + 1;
273 	}
274 
275 	/*
276 	 * bap, if provided, gives us a list of blocks to which we want to
277 	 * stay close
278 	 */
279 
280 	if (bap) {
281 		for (i = indx; i >= 0 ; i--) {
282 			if (bap[i]) {
283 				return fs2h32(bap[i]) + 1;
284 			}
285 		}
286 	}
287 
288 	/* fall back to the first block of the cylinder containing the inode */
289 
290 	cg = ino_to_cg(fs, ip->i_number);
291 	return fs->e2fs.e2fs_bpg * cg + fs->e2fs.e2fs_first_dblock + 1;
292 }
293 
294 /*
295  * Implement the cylinder overflow algorithm.
296  *
297  * The policy implemented by this algorithm is:
298  *   1) allocate the block in its requested cylinder group.
299  *   2) quadradically rehash on the cylinder group number.
300  *   3) brute force search for a free block.
301  */
302 static u_long
303 ext2fs_hashalloc(struct inode *ip, int cg, long pref, int size,
304 		daddr_t (*allocator)(struct inode *, int, daddr_t, int))
305 {
306 	struct m_ext2fs *fs;
307 	long result;
308 	int i, icg = cg;
309 
310 	fs = ip->i_e2fs;
311 	/*
312 	 * 1: preferred cylinder group
313 	 */
314 	result = (*allocator)(ip, cg, pref, size);
315 	if (result)
316 		return (result);
317 	/*
318 	 * 2: quadratic rehash
319 	 */
320 	for (i = 1; i < fs->e2fs_ncg; i *= 2) {
321 		cg += i;
322 		if (cg >= fs->e2fs_ncg)
323 			cg -= fs->e2fs_ncg;
324 		result = (*allocator)(ip, cg, 0, size);
325 		if (result)
326 			return (result);
327 	}
328 	/*
329 	 * 3: brute force search
330 	 * Note that we start at i == 2, since 0 was checked initially,
331 	 * and 1 is always checked in the quadratic rehash.
332 	 */
333 	cg = (icg + 2) % fs->e2fs_ncg;
334 	for (i = 2; i < fs->e2fs_ncg; i++) {
335 		result = (*allocator)(ip, cg, 0, size);
336 		if (result)
337 			return (result);
338 		cg++;
339 		if (cg == fs->e2fs_ncg)
340 			cg = 0;
341 	}
342 	return (0);
343 }
344 
345 /*
346  * Determine whether a block can be allocated.
347  *
348  * Check to see if a block of the appropriate size is available,
349  * and if it is, allocate it.
350  */
351 
352 static daddr_t
353 ext2fs_alloccg(struct inode *ip, int cg, daddr_t bpref, int size)
354 {
355 	struct m_ext2fs *fs;
356 	char *bbp;
357 	struct buf *bp;
358 	/* XXX ondisk32 */
359 	int error, bno, start, end, loc;
360 
361 	fs = ip->i_e2fs;
362 	if (fs->e2fs_gd[cg].ext2bgd_nbfree == 0)
363 		return (0);
364 	error = bread(ip->i_devvp, fsbtodb(fs,
365 		fs->e2fs_gd[cg].ext2bgd_b_bitmap),
366 		(int)fs->e2fs_bsize, NOCRED, B_MODIFY, &bp);
367 	if (error) {
368 		brelse(bp, 0);
369 		return (0);
370 	}
371 	bbp = (char *)bp->b_data;
372 
373 	if (dtog(fs, bpref) != cg)
374 		bpref = 0;
375 	if (bpref != 0) {
376 		bpref = dtogd(fs, bpref);
377 		/*
378 		 * if the requested block is available, use it
379 		 */
380 		if (isclr(bbp, bpref)) {
381 			bno = bpref;
382 			goto gotit;
383 		}
384 	}
385 	/*
386 	 * no blocks in the requested cylinder, so take next
387 	 * available one in this cylinder group.
388 	 * first try to get 8 contigous blocks, then fall back to a single
389 	 * block.
390 	 */
391 	if (bpref)
392 		start = dtogd(fs, bpref) / NBBY;
393 	else
394 		start = 0;
395 	end = howmany(fs->e2fs.e2fs_fpg, NBBY) - start;
396 	for (loc = start; loc < end; loc++) {
397 		if (bbp[loc] == 0) {
398 			bno = loc * NBBY;
399 			goto gotit;
400 		}
401 	}
402 	for (loc = 0; loc < start; loc++) {
403 		if (bbp[loc] == 0) {
404 			bno = loc * NBBY;
405 			goto gotit;
406 		}
407 	}
408 
409 	bno = ext2fs_mapsearch(fs, bbp, bpref);
410 	if (bno < 0)
411 		return (0);
412 gotit:
413 #ifdef DIAGNOSTIC
414 	if (isset(bbp, (daddr_t)bno)) {
415 		printf("ext2fs_alloccgblk: cg=%d bno=%d fs=%s\n",
416 			cg, bno, fs->e2fs_fsmnt);
417 		panic("ext2fs_alloccg: dup alloc");
418 	}
419 #endif
420 	setbit(bbp, (daddr_t)bno);
421 	fs->e2fs.e2fs_fbcount--;
422 	fs->e2fs_gd[cg].ext2bgd_nbfree--;
423 	fs->e2fs_fmod = 1;
424 	bdwrite(bp);
425 	return (cg * fs->e2fs.e2fs_fpg + fs->e2fs.e2fs_first_dblock + bno);
426 }
427 
428 /*
429  * Determine whether an inode can be allocated.
430  *
431  * Check to see if an inode is available, and if it is,
432  * allocate it using the following policy:
433  *   1) allocate the requested inode.
434  *   2) allocate the next available inode after the requested
435  *	  inode in the specified cylinder group.
436  */
437 static daddr_t
438 ext2fs_nodealloccg(struct inode *ip, int cg, daddr_t ipref, int mode)
439 {
440 	struct m_ext2fs *fs;
441 	char *ibp;
442 	struct buf *bp;
443 	int error, start, len, loc, map, i;
444 
445 	ipref--; /* to avoid a lot of (ipref -1) */
446 	if (ipref == -1)
447 		ipref = 0;
448 	fs = ip->i_e2fs;
449 	if (fs->e2fs_gd[cg].ext2bgd_nifree == 0)
450 		return (0);
451 	error = bread(ip->i_devvp, fsbtodb(fs,
452 		fs->e2fs_gd[cg].ext2bgd_i_bitmap),
453 		(int)fs->e2fs_bsize, NOCRED, B_MODIFY, &bp);
454 	if (error) {
455 		brelse(bp, 0);
456 		return (0);
457 	}
458 	ibp = (char *)bp->b_data;
459 	if (ipref) {
460 		ipref %= fs->e2fs.e2fs_ipg;
461 		if (isclr(ibp, ipref))
462 			goto gotit;
463 	}
464 	start = ipref / NBBY;
465 	len = howmany(fs->e2fs.e2fs_ipg - ipref, NBBY);
466 	loc = skpc(0xff, len, &ibp[start]);
467 	if (loc == 0) {
468 		len = start + 1;
469 		start = 0;
470 		loc = skpc(0xff, len, &ibp[0]);
471 		if (loc == 0) {
472 			printf("cg = %d, ipref = %lld, fs = %s\n",
473 				cg, (long long)ipref, fs->e2fs_fsmnt);
474 			panic("ext2fs_nodealloccg: map corrupted");
475 			/* NOTREACHED */
476 		}
477 	}
478 	i = start + len - loc;
479 	map = ibp[i];
480 	ipref = i * NBBY;
481 	for (i = 1; i < (1 << NBBY); i <<= 1, ipref++) {
482 		if ((map & i) == 0) {
483 			goto gotit;
484 		}
485 	}
486 	printf("fs = %s\n", fs->e2fs_fsmnt);
487 	panic("ext2fs_nodealloccg: block not in map");
488 	/* NOTREACHED */
489 gotit:
490 	setbit(ibp, ipref);
491 	fs->e2fs.e2fs_ficount--;
492 	fs->e2fs_gd[cg].ext2bgd_nifree--;
493 	fs->e2fs_fmod = 1;
494 	if ((mode & IFMT) == IFDIR) {
495 		fs->e2fs_gd[cg].ext2bgd_ndirs++;
496 	}
497 	bdwrite(bp);
498 	return (cg * fs->e2fs.e2fs_ipg + ipref +1);
499 }
500 
501 /*
502  * Free a block.
503  *
504  * The specified block is placed back in the
505  * free map.
506  */
507 void
508 ext2fs_blkfree(struct inode *ip, daddr_t bno)
509 {
510 	struct m_ext2fs *fs;
511 	char *bbp;
512 	struct buf *bp;
513 	int error, cg;
514 
515 	fs = ip->i_e2fs;
516 	cg = dtog(fs, bno);
517 	if ((u_int)bno >= fs->e2fs.e2fs_bcount) {
518 		printf("bad block %lld, ino %llu\n", (long long)bno,
519 		    (unsigned long long)ip->i_number);
520 		ext2fs_fserr(fs, ip->i_uid, "bad block");
521 		return;
522 	}
523 	error = bread(ip->i_devvp,
524 		fsbtodb(fs, fs->e2fs_gd[cg].ext2bgd_b_bitmap),
525 		(int)fs->e2fs_bsize, NOCRED, B_MODIFY, &bp);
526 	if (error) {
527 		brelse(bp, 0);
528 		return;
529 	}
530 	bbp = (char *)bp->b_data;
531 	bno = dtogd(fs, bno);
532 	if (isclr(bbp, bno)) {
533 		printf("dev = 0x%llx, block = %lld, fs = %s\n",
534 		    (unsigned long long)ip->i_dev, (long long)bno,
535 		    fs->e2fs_fsmnt);
536 		panic("blkfree: freeing free block");
537 	}
538 	clrbit(bbp, bno);
539 	fs->e2fs.e2fs_fbcount++;
540 	fs->e2fs_gd[cg].ext2bgd_nbfree++;
541 
542 	fs->e2fs_fmod = 1;
543 	bdwrite(bp);
544 }
545 
546 /*
547  * Free an inode.
548  *
549  * The specified inode is placed back in the free map.
550  */
551 int
552 ext2fs_vfree(struct vnode *pvp, ino_t ino, int mode)
553 {
554 	struct m_ext2fs *fs;
555 	char *ibp;
556 	struct inode *pip;
557 	struct buf *bp;
558 	int error, cg;
559 
560 	pip = VTOI(pvp);
561 	fs = pip->i_e2fs;
562 	if ((u_int)ino > fs->e2fs.e2fs_icount || (u_int)ino < EXT2_FIRSTINO)
563 		panic("ifree: range: dev = 0x%llx, ino = %llu, fs = %s",
564 		    (unsigned long long)pip->i_dev, (unsigned long long)ino,
565 		    fs->e2fs_fsmnt);
566 	cg = ino_to_cg(fs, ino);
567 	error = bread(pip->i_devvp,
568 		fsbtodb(fs, fs->e2fs_gd[cg].ext2bgd_i_bitmap),
569 		(int)fs->e2fs_bsize, NOCRED, B_MODIFY, &bp);
570 	if (error) {
571 		brelse(bp, 0);
572 		return (0);
573 	}
574 	ibp = (char *)bp->b_data;
575 	ino = (ino - 1) % fs->e2fs.e2fs_ipg;
576 	if (isclr(ibp, ino)) {
577 		printf("dev = 0x%llx, ino = %llu, fs = %s\n",
578 		    (unsigned long long)pip->i_dev,
579 		    (unsigned long long)ino, fs->e2fs_fsmnt);
580 		if (fs->e2fs_ronly == 0)
581 			panic("ifree: freeing free inode");
582 	}
583 	clrbit(ibp, ino);
584 	fs->e2fs.e2fs_ficount++;
585 	fs->e2fs_gd[cg].ext2bgd_nifree++;
586 	if ((mode & IFMT) == IFDIR) {
587 		fs->e2fs_gd[cg].ext2bgd_ndirs--;
588 	}
589 	fs->e2fs_fmod = 1;
590 	bdwrite(bp);
591 	return (0);
592 }
593 
594 /*
595  * Find a block in the specified cylinder group.
596  *
597  * It is a panic if a request is made to find a block if none are
598  * available.
599  */
600 
601 static daddr_t
602 ext2fs_mapsearch(struct m_ext2fs *fs, char *bbp, daddr_t bpref)
603 {
604 	daddr_t bno;
605 	int start, len, loc, i, map;
606 
607 	/*
608 	 * find the fragment by searching through the free block
609 	 * map for an appropriate bit pattern
610 	 */
611 	if (bpref)
612 		start = dtogd(fs, bpref) / NBBY;
613 	else
614 		start = 0;
615 	len = howmany(fs->e2fs.e2fs_fpg, NBBY) - start;
616 	loc = skpc(0xff, len, &bbp[start]);
617 	if (loc == 0) {
618 		len = start + 1;
619 		start = 0;
620 		loc = skpc(0xff, len, &bbp[start]);
621 		if (loc == 0) {
622 			printf("start = %d, len = %d, fs = %s\n",
623 				start, len, fs->e2fs_fsmnt);
624 			panic("ext2fs_alloccg: map corrupted");
625 			/* NOTREACHED */
626 		}
627 	}
628 	i = start + len - loc;
629 	map = bbp[i];
630 	bno = i * NBBY;
631 	for (i = 1; i < (1 << NBBY); i <<= 1, bno++) {
632 		if ((map & i) == 0)
633 			return (bno);
634 	}
635 	printf("fs = %s\n", fs->e2fs_fsmnt);
636 	panic("ext2fs_mapsearch: block not in map");
637 	/* NOTREACHED */
638 }
639 
640 /*
641  * Fserr prints the name of a file system with an error diagnostic.
642  *
643  * The form of the error message is:
644  *	fs: error message
645  */
646 static void
647 ext2fs_fserr(struct m_ext2fs *fs, u_int uid, const char *cp)
648 {
649 
650 	log(LOG_ERR, "uid %d on %s: %s\n", uid, fs->e2fs_fsmnt, cp);
651 }
652