xref: /netbsd-src/sys/ufs/ext2fs/ext2fs_alloc.c (revision 404fbe5fb94ca1e054339640cabb2801ce52dd30)
1 /*	$NetBSD: ext2fs_alloc.c,v 1.38 2009/01/11 02:45:56 christos 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 1.38 2009/01/11 02:45:56 christos 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_generic(cred, KAUTH_GENERIC_ISSUSER, NULL) != 0 &&
132 	    freespace(fs) <= 0)
133 		goto nospace;
134 	if (bpref >= fs->e2fs.e2fs_bcount)
135 		bpref = 0;
136 	if (bpref == 0)
137 		cg = ino_to_cg(fs, ip->i_number);
138 	else
139 		cg = dtog(fs, bpref);
140 	bno = (daddr_t)ext2fs_hashalloc(ip, cg, bpref, fs->e2fs_bsize,
141 						 ext2fs_alloccg);
142 	if (bno > 0) {
143 		ip->i_e2fs_nblock += btodb(fs->e2fs_bsize);
144 		ip->i_flag |= IN_CHANGE | IN_UPDATE;
145 		*bnp = bno;
146 		return (0);
147 	}
148 nospace:
149 	ext2fs_fserr(fs, kauth_cred_geteuid(cred), "file system full");
150 	uprintf("\n%s: write failed, file system is full\n", fs->e2fs_fsmnt);
151 	return (ENOSPC);
152 }
153 
154 /*
155  * Allocate an inode in the file system.
156  *
157  * If allocating a directory, use ext2fs_dirpref to select the inode.
158  * If allocating in a directory, the following hierarchy is followed:
159  *   1) allocate the preferred inode.
160  *   2) allocate an inode in the same cylinder group.
161  *   3) quadradically rehash into other cylinder groups, until an
162  *	  available inode is located.
163  * If no inode preference is given the following hierarchy is used
164  * to allocate an inode:
165  *   1) allocate an inode in cylinder group 0.
166  *   2) quadradically rehash into other cylinder groups, until an
167  *	  available inode is located.
168  */
169 int
170 ext2fs_valloc(struct vnode *pvp, int mode, kauth_cred_t cred,
171     struct vnode **vpp)
172 {
173 	struct inode *pip;
174 	struct m_ext2fs *fs;
175 	struct inode *ip;
176 	ino_t ino, ipref;
177 	int cg, error;
178 
179 	*vpp = NULL;
180 	pip = VTOI(pvp);
181 	fs = pip->i_e2fs;
182 	if (fs->e2fs.e2fs_ficount == 0)
183 		goto noinodes;
184 
185 	if ((mode & IFMT) == IFDIR)
186 		cg = ext2fs_dirpref(fs);
187 	else
188 		cg = ino_to_cg(fs, pip->i_number);
189 	ipref = cg * fs->e2fs.e2fs_ipg + 1;
190 	ino = (ino_t)ext2fs_hashalloc(pip, cg, (long)ipref, mode, ext2fs_nodealloccg);
191 	if (ino == 0)
192 		goto noinodes;
193 	error = VFS_VGET(pvp->v_mount, ino, vpp);
194 	if (error) {
195 		ext2fs_vfree(pvp, ino, mode);
196 		return (error);
197 	}
198 	ip = VTOI(*vpp);
199 	if (ip->i_e2fs_mode && ip->i_e2fs_nlink != 0) {
200 		printf("mode = 0%o, nlinks %d, inum = %llu, fs = %s\n",
201 		    ip->i_e2fs_mode, ip->i_e2fs_nlink,
202 		    (unsigned long long)ip->i_number, fs->e2fs_fsmnt);
203 		panic("ext2fs_valloc: dup alloc");
204 	}
205 
206 	memset(ip->i_din.e2fs_din, 0, sizeof(struct ext2fs_dinode));
207 
208 	/*
209 	 * Set up a new generation number for this inode.
210 	 */
211 	if (++ext2gennumber < time_second)
212 		ext2gennumber = time_second;
213 	ip->i_e2fs_gen = ext2gennumber;
214 	return (0);
215 noinodes:
216 	ext2fs_fserr(fs, kauth_cred_geteuid(cred), "out of inodes");
217 	uprintf("\n%s: create/symlink failed, no inodes free\n", fs->e2fs_fsmnt);
218 	return (ENOSPC);
219 }
220 
221 /*
222  * Find a cylinder to place a directory.
223  *
224  * The policy implemented by this algorithm is to select from
225  * among those cylinder groups with above the average number of
226  * free inodes, the one with the smallest number of directories.
227  */
228 static u_long
229 ext2fs_dirpref(struct m_ext2fs *fs)
230 {
231 	int cg, maxspace, mincg, avgifree;
232 
233 	avgifree = fs->e2fs.e2fs_ficount / fs->e2fs_ncg;
234 	maxspace = 0;
235 	mincg = -1;
236 	for (cg = 0; cg < fs->e2fs_ncg; cg++)
237 		if ( fs->e2fs_gd[cg].ext2bgd_nifree >= avgifree) {
238 			if (mincg == -1 || fs->e2fs_gd[cg].ext2bgd_nbfree > maxspace) {
239 				mincg = cg;
240 				maxspace = fs->e2fs_gd[cg].ext2bgd_nbfree;
241 			}
242 		}
243 	return mincg;
244 }
245 
246 /*
247  * Select the desired position for the next block in a file.  The file is
248  * logically divided into sections. The first section is composed of the
249  * direct blocks. Each additional section contains fs_maxbpg blocks.
250  *
251  * If no blocks have been allocated in the first section, the policy is to
252  * request a block in the same cylinder group as the inode that describes
253  * the file. Otherwise, the policy is to try to allocate the blocks
254  * contigously. The two fields of the ext2 inode extension (see
255  * ufs/ufs/inode.h) help this.
256  */
257 daddr_t
258 ext2fs_blkpref(struct inode *ip, daddr_t lbn, int indx,
259 		int32_t *bap /* XXX ondisk32 */)
260 {
261 	struct m_ext2fs *fs;
262 	int cg, i;
263 
264 	fs = ip->i_e2fs;
265 	/*
266 	 * if we are doing contigous lbn allocation, try to alloc blocks
267 	 * contigously on disk
268 	 */
269 
270 	if ( ip->i_e2fs_last_blk && lbn == ip->i_e2fs_last_lblk + 1) {
271 		return ip->i_e2fs_last_blk + 1;
272 	}
273 
274 	/*
275 	 * bap, if provided, gives us a list of blocks to which we want to
276 	 * stay close
277 	 */
278 
279 	if (bap) {
280 		for (i = indx; i >= 0 ; i--) {
281 			if (bap[i]) {
282 				return fs2h32(bap[i]) + 1;
283 			}
284 		}
285 	}
286 
287 	/* fall back to the first block of the cylinder containing the inode */
288 
289 	cg = ino_to_cg(fs, ip->i_number);
290 	return fs->e2fs.e2fs_bpg * cg + fs->e2fs.e2fs_first_dblock + 1;
291 }
292 
293 /*
294  * Implement the cylinder overflow algorithm.
295  *
296  * The policy implemented by this algorithm is:
297  *   1) allocate the block in its requested cylinder group.
298  *   2) quadradically rehash on the cylinder group number.
299  *   3) brute force search for a free block.
300  */
301 static u_long
302 ext2fs_hashalloc(struct inode *ip, int cg, long pref, int size,
303 		daddr_t (*allocator)(struct inode *, int, daddr_t, int))
304 {
305 	struct m_ext2fs *fs;
306 	long result;
307 	int i, icg = cg;
308 
309 	fs = ip->i_e2fs;
310 	/*
311 	 * 1: preferred cylinder group
312 	 */
313 	result = (*allocator)(ip, cg, pref, size);
314 	if (result)
315 		return (result);
316 	/*
317 	 * 2: quadratic rehash
318 	 */
319 	for (i = 1; i < fs->e2fs_ncg; i *= 2) {
320 		cg += i;
321 		if (cg >= fs->e2fs_ncg)
322 			cg -= fs->e2fs_ncg;
323 		result = (*allocator)(ip, cg, 0, size);
324 		if (result)
325 			return (result);
326 	}
327 	/*
328 	 * 3: brute force search
329 	 * Note that we start at i == 2, since 0 was checked initially,
330 	 * and 1 is always checked in the quadratic rehash.
331 	 */
332 	cg = (icg + 2) % fs->e2fs_ncg;
333 	for (i = 2; i < fs->e2fs_ncg; i++) {
334 		result = (*allocator)(ip, cg, 0, size);
335 		if (result)
336 			return (result);
337 		cg++;
338 		if (cg == fs->e2fs_ncg)
339 			cg = 0;
340 	}
341 	return (0);
342 }
343 
344 /*
345  * Determine whether a block can be allocated.
346  *
347  * Check to see if a block of the appropriate size is available,
348  * and if it is, allocate it.
349  */
350 
351 static daddr_t
352 ext2fs_alloccg(struct inode *ip, int cg, daddr_t bpref, int size)
353 {
354 	struct m_ext2fs *fs;
355 	char *bbp;
356 	struct buf *bp;
357 	/* XXX ondisk32 */
358 	int error, bno, start, end, loc;
359 
360 	fs = ip->i_e2fs;
361 	if (fs->e2fs_gd[cg].ext2bgd_nbfree == 0)
362 		return (0);
363 	error = bread(ip->i_devvp, fsbtodb(fs,
364 		fs->e2fs_gd[cg].ext2bgd_b_bitmap),
365 		(int)fs->e2fs_bsize, NOCRED, B_MODIFY, &bp);
366 	if (error) {
367 		brelse(bp, 0);
368 		return (0);
369 	}
370 	bbp = (char *)bp->b_data;
371 
372 	if (dtog(fs, bpref) != cg)
373 		bpref = 0;
374 	if (bpref != 0) {
375 		bpref = dtogd(fs, bpref);
376 		/*
377 		 * if the requested block is available, use it
378 		 */
379 		if (isclr(bbp, bpref)) {
380 			bno = bpref;
381 			goto gotit;
382 		}
383 	}
384 	/*
385 	 * no blocks in the requested cylinder, so take next
386 	 * available one in this cylinder group.
387 	 * first try to get 8 contigous blocks, then fall back to a single
388 	 * block.
389 	 */
390 	if (bpref)
391 		start = dtogd(fs, bpref) / NBBY;
392 	else
393 		start = 0;
394 	end = howmany(fs->e2fs.e2fs_fpg, NBBY) - start;
395 	for (loc = start; loc < end; loc++) {
396 		if (bbp[loc] == 0) {
397 			bno = loc * NBBY;
398 			goto gotit;
399 		}
400 	}
401 	for (loc = 0; loc < start; loc++) {
402 		if (bbp[loc] == 0) {
403 			bno = loc * NBBY;
404 			goto gotit;
405 		}
406 	}
407 
408 	bno = ext2fs_mapsearch(fs, bbp, bpref);
409 	if (bno < 0)
410 		return (0);
411 gotit:
412 #ifdef DIAGNOSTIC
413 	if (isset(bbp, (daddr_t)bno)) {
414 		printf("ext2fs_alloccgblk: cg=%d bno=%d fs=%s\n",
415 			cg, bno, fs->e2fs_fsmnt);
416 		panic("ext2fs_alloccg: dup alloc");
417 	}
418 #endif
419 	setbit(bbp, (daddr_t)bno);
420 	fs->e2fs.e2fs_fbcount--;
421 	fs->e2fs_gd[cg].ext2bgd_nbfree--;
422 	fs->e2fs_fmod = 1;
423 	bdwrite(bp);
424 	return (cg * fs->e2fs.e2fs_fpg + fs->e2fs.e2fs_first_dblock + bno);
425 }
426 
427 /*
428  * Determine whether an inode can be allocated.
429  *
430  * Check to see if an inode is available, and if it is,
431  * allocate it using the following policy:
432  *   1) allocate the requested inode.
433  *   2) allocate the next available inode after the requested
434  *	  inode in the specified cylinder group.
435  */
436 static daddr_t
437 ext2fs_nodealloccg(struct inode *ip, int cg, daddr_t ipref, int mode)
438 {
439 	struct m_ext2fs *fs;
440 	char *ibp;
441 	struct buf *bp;
442 	int error, start, len, loc, map, i;
443 
444 	ipref--; /* to avoid a lot of (ipref -1) */
445 	if (ipref == -1)
446 		ipref = 0;
447 	fs = ip->i_e2fs;
448 	if (fs->e2fs_gd[cg].ext2bgd_nifree == 0)
449 		return (0);
450 	error = bread(ip->i_devvp, fsbtodb(fs,
451 		fs->e2fs_gd[cg].ext2bgd_i_bitmap),
452 		(int)fs->e2fs_bsize, NOCRED, B_MODIFY, &bp);
453 	if (error) {
454 		brelse(bp, 0);
455 		return (0);
456 	}
457 	ibp = (char *)bp->b_data;
458 	if (ipref) {
459 		ipref %= fs->e2fs.e2fs_ipg;
460 		if (isclr(ibp, ipref))
461 			goto gotit;
462 	}
463 	start = ipref / NBBY;
464 	len = howmany(fs->e2fs.e2fs_ipg - ipref, NBBY);
465 	loc = skpc(0xff, len, &ibp[start]);
466 	if (loc == 0) {
467 		len = start + 1;
468 		start = 0;
469 		loc = skpc(0xff, len, &ibp[0]);
470 		if (loc == 0) {
471 			printf("cg = %d, ipref = %lld, fs = %s\n",
472 				cg, (long long)ipref, fs->e2fs_fsmnt);
473 			panic("ext2fs_nodealloccg: map corrupted");
474 			/* NOTREACHED */
475 		}
476 	}
477 	i = start + len - loc;
478 	map = ibp[i];
479 	ipref = i * NBBY;
480 	for (i = 1; i < (1 << NBBY); i <<= 1, ipref++) {
481 		if ((map & i) == 0) {
482 			goto gotit;
483 		}
484 	}
485 	printf("fs = %s\n", fs->e2fs_fsmnt);
486 	panic("ext2fs_nodealloccg: block not in map");
487 	/* NOTREACHED */
488 gotit:
489 	setbit(ibp, ipref);
490 	fs->e2fs.e2fs_ficount--;
491 	fs->e2fs_gd[cg].ext2bgd_nifree--;
492 	fs->e2fs_fmod = 1;
493 	if ((mode & IFMT) == IFDIR) {
494 		fs->e2fs_gd[cg].ext2bgd_ndirs++;
495 	}
496 	bdwrite(bp);
497 	return (cg * fs->e2fs.e2fs_ipg + ipref +1);
498 }
499 
500 /*
501  * Free a block.
502  *
503  * The specified block is placed back in the
504  * free map.
505  */
506 void
507 ext2fs_blkfree(struct inode *ip, daddr_t bno)
508 {
509 	struct m_ext2fs *fs;
510 	char *bbp;
511 	struct buf *bp;
512 	int error, cg;
513 
514 	fs = ip->i_e2fs;
515 	cg = dtog(fs, bno);
516 	if ((u_int)bno >= fs->e2fs.e2fs_bcount) {
517 		printf("bad block %lld, ino %llu\n", (long long)bno,
518 		    (unsigned long long)ip->i_number);
519 		ext2fs_fserr(fs, ip->i_uid, "bad block");
520 		return;
521 	}
522 	error = bread(ip->i_devvp,
523 		fsbtodb(fs, fs->e2fs_gd[cg].ext2bgd_b_bitmap),
524 		(int)fs->e2fs_bsize, NOCRED, B_MODIFY, &bp);
525 	if (error) {
526 		brelse(bp, 0);
527 		return;
528 	}
529 	bbp = (char *)bp->b_data;
530 	bno = dtogd(fs, bno);
531 	if (isclr(bbp, bno)) {
532 		printf("dev = 0x%llx, block = %lld, fs = %s\n",
533 		    (unsigned long long)ip->i_dev, (long long)bno,
534 		    fs->e2fs_fsmnt);
535 		panic("blkfree: freeing free block");
536 	}
537 	clrbit(bbp, bno);
538 	fs->e2fs.e2fs_fbcount++;
539 	fs->e2fs_gd[cg].ext2bgd_nbfree++;
540 
541 	fs->e2fs_fmod = 1;
542 	bdwrite(bp);
543 }
544 
545 /*
546  * Free an inode.
547  *
548  * The specified inode is placed back in the free map.
549  */
550 int
551 ext2fs_vfree(struct vnode *pvp, ino_t ino, int mode)
552 {
553 	struct m_ext2fs *fs;
554 	char *ibp;
555 	struct inode *pip;
556 	struct buf *bp;
557 	int error, cg;
558 
559 	pip = VTOI(pvp);
560 	fs = pip->i_e2fs;
561 	if ((u_int)ino > fs->e2fs.e2fs_icount || (u_int)ino < EXT2_FIRSTINO)
562 		panic("ifree: range: dev = 0x%llx, ino = %llu, fs = %s",
563 		    (unsigned long long)pip->i_dev, (unsigned long long)ino,
564 		    fs->e2fs_fsmnt);
565 	cg = ino_to_cg(fs, ino);
566 	error = bread(pip->i_devvp,
567 		fsbtodb(fs, fs->e2fs_gd[cg].ext2bgd_i_bitmap),
568 		(int)fs->e2fs_bsize, NOCRED, B_MODIFY, &bp);
569 	if (error) {
570 		brelse(bp, 0);
571 		return (0);
572 	}
573 	ibp = (char *)bp->b_data;
574 	ino = (ino - 1) % fs->e2fs.e2fs_ipg;
575 	if (isclr(ibp, ino)) {
576 		printf("dev = 0x%llx, ino = %llu, fs = %s\n",
577 		    (unsigned long long)pip->i_dev,
578 		    (unsigned long long)ino, fs->e2fs_fsmnt);
579 		if (fs->e2fs_ronly == 0)
580 			panic("ifree: freeing free inode");
581 	}
582 	clrbit(ibp, ino);
583 	fs->e2fs.e2fs_ficount++;
584 	fs->e2fs_gd[cg].ext2bgd_nifree++;
585 	if ((mode & IFMT) == IFDIR) {
586 		fs->e2fs_gd[cg].ext2bgd_ndirs--;
587 	}
588 	fs->e2fs_fmod = 1;
589 	bdwrite(bp);
590 	return (0);
591 }
592 
593 /*
594  * Find a block in the specified cylinder group.
595  *
596  * It is a panic if a request is made to find a block if none are
597  * available.
598  */
599 
600 static daddr_t
601 ext2fs_mapsearch(struct m_ext2fs *fs, char *bbp, daddr_t bpref)
602 {
603 	daddr_t bno;
604 	int start, len, loc, i, map;
605 
606 	/*
607 	 * find the fragment by searching through the free block
608 	 * map for an appropriate bit pattern
609 	 */
610 	if (bpref)
611 		start = dtogd(fs, bpref) / NBBY;
612 	else
613 		start = 0;
614 	len = howmany(fs->e2fs.e2fs_fpg, NBBY) - start;
615 	loc = skpc(0xff, len, &bbp[start]);
616 	if (loc == 0) {
617 		len = start + 1;
618 		start = 0;
619 		loc = skpc(0xff, len, &bbp[start]);
620 		if (loc == 0) {
621 			printf("start = %d, len = %d, fs = %s\n",
622 				start, len, fs->e2fs_fsmnt);
623 			panic("ext2fs_alloccg: map corrupted");
624 			/* NOTREACHED */
625 		}
626 	}
627 	i = start + len - loc;
628 	map = bbp[i];
629 	bno = i * NBBY;
630 	for (i = 1; i < (1 << NBBY); i <<= 1, bno++) {
631 		if ((map & i) == 0)
632 			return (bno);
633 	}
634 	printf("fs = %s\n", fs->e2fs_fsmnt);
635 	panic("ext2fs_mapsearch: block not in map");
636 	/* NOTREACHED */
637 }
638 
639 /*
640  * Fserr prints the name of a file system with an error diagnostic.
641  *
642  * The form of the error message is:
643  *	fs: error message
644  */
645 static void
646 ext2fs_fserr(struct m_ext2fs *fs, u_int uid, const char *cp)
647 {
648 
649 	log(LOG_ERR, "uid %d on %s: %s\n", uid, fs->e2fs_fsmnt, cp);
650 }
651