xref: /freebsd/sys/fs/ext2fs/ext2_lookup.c (revision 8d20be1e22095c27faf8fe8b2f0d089739cc742e)
1 /*-
2  *  modified for Lites 1.1
3  *
4  *  Aug 1995, Godmar Back (gback@cs.utah.edu)
5  *  University of Utah, Department of Computer Science
6  */
7 /*-
8  * Copyright (c) 1989, 1993
9  *	The Regents of the University of California.  All rights reserved.
10  * (c) UNIX System Laboratories, Inc.
11  * All or some portions of this file are derived from material licensed
12  * to the University of California by American Telephone and Telegraph
13  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
14  * the permission of UNIX System Laboratories, Inc.
15  *
16  * Redistribution and use in source and binary forms, with or without
17  * modification, are permitted provided that the following conditions
18  * are met:
19  * 1. Redistributions of source code must retain the above copyright
20  *    notice, this list of conditions and the following disclaimer.
21  * 2. Redistributions in binary form must reproduce the above copyright
22  *    notice, this list of conditions and the following disclaimer in the
23  *    documentation and/or other materials provided with the distribution.
24  * 4. Neither the name of the University nor the names of its contributors
25  *    may be used to endorse or promote products derived from this software
26  *    without specific prior written permission.
27  *
28  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38  * SUCH DAMAGE.
39  *
40  *	@(#)ufs_lookup.c	8.6 (Berkeley) 4/1/94
41  * $FreeBSD$
42  */
43 
44 #include <sys/param.h>
45 #include <sys/systm.h>
46 #include <sys/namei.h>
47 #include <sys/bio.h>
48 #include <sys/buf.h>
49 #include <sys/endian.h>
50 #include <sys/mount.h>
51 #include <sys/vnode.h>
52 #include <sys/malloc.h>
53 #include <sys/dirent.h>
54 #include <sys/sysctl.h>
55 
56 #include <ufs/ufs/dir.h>
57 
58 #include <fs/ext2fs/inode.h>
59 #include <fs/ext2fs/ext2_mount.h>
60 #include <fs/ext2fs/ext2fs.h>
61 #include <fs/ext2fs/ext2_dinode.h>
62 #include <fs/ext2fs/ext2_dir.h>
63 #include <fs/ext2fs/ext2_extern.h>
64 
65 #ifdef INVARIANTS
66 static int dirchk = 1;
67 #else
68 static int dirchk = 0;
69 #endif
70 
71 static SYSCTL_NODE(_vfs, OID_AUTO, e2fs, CTLFLAG_RD, 0, "EXT2FS filesystem");
72 SYSCTL_INT(_vfs_e2fs, OID_AUTO, dircheck, CTLFLAG_RW, &dirchk, 0, "");
73 
74 /*
75    DIRBLKSIZE in ffs is DEV_BSIZE (in most cases 512)
76    while it is the native blocksize in ext2fs - thus, a #define
77    is no longer appropriate
78 */
79 #undef  DIRBLKSIZ
80 
81 static u_char ext2_ft_to_dt[] = {
82 	DT_UNKNOWN,		/* EXT2_FT_UNKNOWN */
83 	DT_REG,			/* EXT2_FT_REG_FILE */
84 	DT_DIR,			/* EXT2_FT_DIR */
85 	DT_CHR,			/* EXT2_FT_CHRDEV */
86 	DT_BLK,			/* EXT2_FT_BLKDEV */
87 	DT_FIFO,		/* EXT2_FT_FIFO */
88 	DT_SOCK,		/* EXT2_FT_SOCK */
89 	DT_LNK,			/* EXT2_FT_SYMLINK */
90 };
91 #define	FTTODT(ft) \
92     ((ft) < nitems(ext2_ft_to_dt) ? ext2_ft_to_dt[(ft)] : DT_UNKNOWN)
93 
94 static u_char dt_to_ext2_ft[] = {
95 	EXT2_FT_UNKNOWN,	/* DT_UNKNOWN */
96 	EXT2_FT_FIFO,		/* DT_FIFO */
97 	EXT2_FT_CHRDEV,		/* DT_CHR */
98 	EXT2_FT_UNKNOWN,	/* unused */
99 	EXT2_FT_DIR,		/* DT_DIR */
100 	EXT2_FT_UNKNOWN,	/* unused */
101 	EXT2_FT_BLKDEV,		/* DT_BLK */
102 	EXT2_FT_UNKNOWN,	/* unused */
103 	EXT2_FT_REG_FILE,	/* DT_REG */
104 	EXT2_FT_UNKNOWN,	/* unused */
105 	EXT2_FT_SYMLINK,	/* DT_LNK */
106 	EXT2_FT_UNKNOWN,	/* unused */
107 	EXT2_FT_SOCK,		/* DT_SOCK */
108 	EXT2_FT_UNKNOWN,	/* unused */
109 	EXT2_FT_UNKNOWN,	/* DT_WHT */
110 };
111 #define	DTTOFT(dt) \
112     ((dt) < nitems(dt_to_ext2_ft) ? dt_to_ext2_ft[(dt)] : EXT2_FT_UNKNOWN)
113 
114 static int	ext2_dirbadentry(struct vnode *dp, struct ext2fs_direct_2 *de,
115 		    int entryoffsetinblock);
116 static int	ext2_is_dot_entry(struct componentname *cnp);
117 static int	ext2_lookup_ino(struct vnode *vdp, struct vnode **vpp,
118 		    struct componentname *cnp, ino_t *dd_ino);
119 
120 static int
121 ext2_is_dot_entry(struct componentname *cnp)
122 {
123 	if (cnp->cn_namelen <= 2 && cnp->cn_nameptr[0] == '.' &&
124 	    (cnp->cn_nameptr[1] == '.' || cnp->cn_nameptr[1] == '0'))
125 		return (1);
126 	return (0);
127 }
128 
129 /*
130  * Vnode op for reading directories.
131  */
132 int
133 ext2_readdir(struct vop_readdir_args *ap)
134 {
135 	struct vnode *vp = ap->a_vp;
136 	struct uio *uio = ap->a_uio;
137 	struct buf *bp;
138 	struct inode *ip;
139 	struct ext2fs_direct_2 *dp, *edp;
140 	u_long *cookies;
141 	struct dirent dstdp;
142 	off_t offset, startoffset;
143 	size_t readcnt, skipcnt;
144 	ssize_t startresid;
145 	int ncookies;
146 	int DIRBLKSIZ = VTOI(ap->a_vp)->i_e2fs->e2fs_bsize;
147 	int error;
148 
149 	if (uio->uio_offset < 0)
150 		return (EINVAL);
151 	ip = VTOI(vp);
152 	if (ap->a_ncookies != NULL) {
153 		ncookies = uio->uio_resid;
154 		if (uio->uio_offset >= ip->i_size)
155 			ncookies = 0;
156 		else if (ip->i_size - uio->uio_offset < ncookies)
157 			ncookies = ip->i_size - uio->uio_offset;
158 		ncookies = ncookies / (offsetof(struct ext2fs_direct_2,
159 		    e2d_namlen) + 4) + 1;
160 		cookies = malloc(ncookies * sizeof(*cookies), M_TEMP, M_WAITOK);
161 		*ap->a_ncookies = ncookies;
162 		*ap->a_cookies = cookies;
163 	} else {
164 		ncookies = 0;
165 		cookies = NULL;
166 	}
167 	offset = startoffset = uio->uio_offset;
168 	startresid = uio->uio_resid;
169 	error = 0;
170 	while (error == 0 && uio->uio_resid > 0 &&
171 	    uio->uio_offset < ip->i_size) {
172 		error = ext2_blkatoff(vp, uio->uio_offset, NULL, &bp);
173 		if (error)
174 			break;
175 		if (bp->b_offset + bp->b_bcount > ip->i_size)
176 			readcnt = ip->i_size - bp->b_offset;
177 		else
178 			readcnt = bp->b_bcount;
179 		skipcnt = (size_t)(uio->uio_offset - bp->b_offset) &
180 		    ~(size_t)(DIRBLKSIZ - 1);
181 		offset = bp->b_offset + skipcnt;
182 		dp = (struct ext2fs_direct_2 *)&bp->b_data[skipcnt];
183 		edp = (struct ext2fs_direct_2 *)&bp->b_data[readcnt];
184 		while (error == 0 && uio->uio_resid > 0 && dp < edp) {
185 			if (dp->e2d_reclen <= offsetof(struct ext2fs_direct_2,
186 			    e2d_namlen) || (caddr_t)dp + dp->e2d_reclen >
187 			    (caddr_t)edp) {
188 				error = EIO;
189 				break;
190 			}
191 			/*-
192 			 * "New" ext2fs directory entries differ in 3 ways
193 			 * from ufs on-disk ones:
194 			 * - the name is not necessarily NUL-terminated.
195 			 * - the file type field always exists and always
196 			 *   follows the name length field.
197 			 * - the file type is encoded in a different way.
198 			 *
199 			 * "Old" ext2fs directory entries need no special
200 			 * conversions, since they are binary compatible
201 			 * with "new" entries having a file type of 0 (i.e.,
202 			 * EXT2_FT_UNKNOWN).  Splitting the old name length
203 			 * field didn't make a mess like it did in ufs,
204 			 * because ext2fs uses a machine-independent disk
205 			 * layout.
206 			 */
207 			dstdp.d_namlen = dp->e2d_namlen;
208 			dstdp.d_type = FTTODT(dp->e2d_type);
209 			if (offsetof(struct ext2fs_direct_2, e2d_namlen) +
210 			    dstdp.d_namlen > dp->e2d_reclen) {
211 				error = EIO;
212 				break;
213 			}
214 			if (offset < startoffset || dp->e2d_ino == 0)
215 				goto nextentry;
216 			dstdp.d_fileno = dp->e2d_ino;
217 			dstdp.d_reclen = GENERIC_DIRSIZ(&dstdp);
218 			bcopy(dp->e2d_name, dstdp.d_name, dstdp.d_namlen);
219 			dstdp.d_name[dstdp.d_namlen] = '\0';
220 			if (dstdp.d_reclen > uio->uio_resid) {
221 				if (uio->uio_resid == startresid)
222 					error = EINVAL;
223 				else
224 					error = EJUSTRETURN;
225 				break;
226 			}
227 			/* Advance dp. */
228 			error = uiomove((caddr_t)&dstdp, dstdp.d_reclen, uio);
229 			if (error)
230 				break;
231 			if (cookies != NULL) {
232 				KASSERT(ncookies > 0,
233 				    ("ext2_readdir: cookies buffer too small"));
234 				*cookies = offset + dp->e2d_reclen;
235 				cookies++;
236 				ncookies--;
237 			}
238 nextentry:
239 			offset += dp->e2d_reclen;
240 			dp = (struct ext2fs_direct_2 *)((caddr_t)dp +
241 			   dp->e2d_reclen);
242 		}
243 		bqrelse(bp);
244 		uio->uio_offset = offset;
245 	}
246 	/* We need to correct uio_offset. */
247 	uio->uio_offset = offset;
248 	if (error == EJUSTRETURN)
249 		error = 0;
250 	if (ap->a_ncookies != NULL) {
251 		if (error == 0) {
252 			ap->a_ncookies -= ncookies;
253 		} else {
254 			free(*ap->a_cookies, M_TEMP);
255 			*ap->a_ncookies = 0;
256 			*ap->a_cookies = NULL;
257 		}
258 	}
259 	if (error == 0 && ap->a_eofflag)
260 		*ap->a_eofflag = ip->i_size <= uio->uio_offset;
261 	return (error);
262 }
263 
264 /*
265  * Convert a component of a pathname into a pointer to a locked inode.
266  * This is a very central and rather complicated routine.
267  * If the file system is not maintained in a strict tree hierarchy,
268  * this can result in a deadlock situation (see comments in code below).
269  *
270  * The cnp->cn_nameiop argument is LOOKUP, CREATE, RENAME, or DELETE depending
271  * on whether the name is to be looked up, created, renamed, or deleted.
272  * When CREATE, RENAME, or DELETE is specified, information usable in
273  * creating, renaming, or deleting a directory entry may be calculated.
274  * If flag has LOCKPARENT or'ed into it and the target of the pathname
275  * exists, lookup returns both the target and its parent directory locked.
276  * When creating or renaming and LOCKPARENT is specified, the target may
277  * not be ".".  When deleting and LOCKPARENT is specified, the target may
278  * be "."., but the caller must check to ensure it does an vrele and vput
279  * instead of two vputs.
280  *
281  * Overall outline of ext2_lookup:
282  *
283  *	search for name in directory, to found or notfound
284  * notfound:
285  *	if creating, return locked directory, leaving info on available slots
286  *	else return error
287  * found:
288  *	if at end of path and deleting, return information to allow delete
289  *	if at end of path and rewriting (RENAME and LOCKPARENT), lock target
290  *	  inode and return info to allow rewrite
291  *	if not at end, add name to cache; if at end and neither creating
292  *	  nor deleting, add name to cache
293  */
294 int
295 ext2_lookup(struct vop_cachedlookup_args *ap)
296 {
297 
298 	return (ext2_lookup_ino(ap->a_dvp, ap->a_vpp, ap->a_cnp, NULL));
299 }
300 
301 static int
302 ext2_lookup_ino(struct vnode *vdp, struct vnode **vpp, struct componentname *cnp,
303     ino_t *dd_ino)
304 {
305 	struct inode *dp;		/* inode for directory being searched */
306 	struct buf *bp;			/* a buffer of directory entries */
307 	struct ext2fs_direct_2 *ep;	/* the current directory entry */
308 	int entryoffsetinblock;		/* offset of ep in bp's buffer */
309 	struct ext2fs_searchslot ss;
310 	doff_t i_diroff;		/* cached i_diroff value */
311 	doff_t i_offset;		/* cached i_offset value */
312 	int numdirpasses;		/* strategy for directory search */
313 	doff_t endsearch;		/* offset to end directory search */
314 	doff_t prevoff;			/* prev entry dp->i_offset */
315 	struct vnode *pdp;		/* saved dp during symlink work */
316 	struct vnode *tdp;		/* returned by VFS_VGET */
317 	doff_t enduseful;		/* pointer past last used dir slot */
318 	u_long bmask;			/* block offset mask */
319 	int error;
320 	struct ucred *cred = cnp->cn_cred;
321 	int flags = cnp->cn_flags;
322 	int nameiop = cnp->cn_nameiop;
323 	ino_t ino, ino1;
324 	int ltype;
325 	int entry_found = 0;
326 
327 	int	DIRBLKSIZ = VTOI(vdp)->i_e2fs->e2fs_bsize;
328 
329 	if (vpp != NULL)
330 		*vpp = NULL;
331 
332 	dp = VTOI(vdp);
333 	bmask = VFSTOEXT2(vdp->v_mount)->um_mountp->mnt_stat.f_iosize - 1;
334 restart:
335 	bp = NULL;
336 	ss.slotoffset = -1;
337 
338 	/*
339 	 * We now have a segment name to search for, and a directory to search.
340 	 *
341 	 * Suppress search for slots unless creating
342 	 * file and at end of pathname, in which case
343 	 * we watch for a place to put the new file in
344 	 * case it doesn't already exist.
345 	 */
346 	ino = 0;
347 	i_diroff = dp->i_diroff;
348 	ss.slotstatus = FOUND;
349 	ss.slotfreespace = ss.slotsize = ss.slotneeded = 0;
350 	if ((nameiop == CREATE || nameiop == RENAME) &&
351 	    (flags & ISLASTCN)) {
352 		ss.slotstatus = NONE;
353 		ss.slotneeded = EXT2_DIR_REC_LEN(cnp->cn_namelen);
354 		/* was
355 		ss.slotneeded = (sizeof(struct direct) - MAXNAMLEN +
356 			cnp->cn_namelen + 3) &~ 3; */
357 	}
358 
359 	/*
360 	 * Try to lookup dir entry using htree directory index.
361 	 *
362 	 * If we got an error or we want to find '.' or '..' entry,
363 	 * we will fall back to linear search.
364 	 */
365 	if (!ext2_is_dot_entry(cnp) && ext2_htree_has_idx(dp)) {
366 		numdirpasses = 1;
367 		entryoffsetinblock = 0;
368 		switch (ext2_htree_lookup(dp, cnp->cn_nameptr, cnp->cn_namelen,
369 				&bp, &entryoffsetinblock, &i_offset, &prevoff,
370 				&enduseful, &ss)) {
371 		case 0:
372 			ep = (struct ext2fs_direct_2 *)((char *)bp->b_data +
373 				(i_offset & bmask));
374 			goto foundentry;
375 		case ENOENT:
376 			i_offset = roundup2(dp->i_size, DIRBLKSIZ);
377 			goto notfound;
378 		default:
379 			/*
380 			 * Something failed; just fallback to do a linear
381 			 * search.
382 			 */
383 			break;
384 		}
385 	}
386 
387 	/*
388 	 * If there is cached information on a previous search of
389 	 * this directory, pick up where we last left off.
390 	 * We cache only lookups as these are the most common
391 	 * and have the greatest payoff. Caching CREATE has little
392 	 * benefit as it usually must search the entire directory
393 	 * to determine that the entry does not exist. Caching the
394 	 * location of the last DELETE or RENAME has not reduced
395 	 * profiling time and hence has been removed in the interest
396 	 * of simplicity.
397 	 */
398 	if (nameiop != LOOKUP || i_diroff == 0 ||
399 	    i_diroff > dp->i_size) {
400 		entryoffsetinblock = 0;
401 		i_offset = 0;
402 		numdirpasses = 1;
403 	} else {
404 		i_offset = i_diroff;
405 		if ((entryoffsetinblock = i_offset & bmask) &&
406 		    (error = ext2_blkatoff(vdp, (off_t)i_offset, NULL,
407 		    &bp)))
408 			return (error);
409 		numdirpasses = 2;
410 		nchstats.ncs_2passes++;
411 	}
412 	prevoff = i_offset;
413 	endsearch = roundup2(dp->i_size, DIRBLKSIZ);
414 	enduseful = 0;
415 
416 searchloop:
417 	while (i_offset < endsearch) {
418 		/*
419 		 * If necessary, get the next directory block.
420 		 */
421 		if (bp != NULL)
422 			brelse(bp);
423 		error = ext2_blkatoff(vdp, (off_t)i_offset, NULL, &bp);
424 		if (error != 0)
425 			return (error);
426 		entryoffsetinblock = 0;
427 		/*
428 		 * If still looking for a slot, and at a DIRBLKSIZE
429 		 * boundary, have to start looking for free space again.
430 		 */
431 		if (ss.slotstatus == NONE &&
432 		    (entryoffsetinblock & (DIRBLKSIZ - 1)) == 0) {
433 			ss.slotoffset = -1;
434 			ss.slotfreespace = 0;
435 		}
436 		error = ext2_search_dirblock(dp, bp->b_data, &entry_found,
437 				cnp->cn_nameptr, cnp->cn_namelen,
438 				&entryoffsetinblock, &i_offset, &prevoff,
439 				&enduseful, &ss);
440 		if (error != 0) {
441 			brelse(bp);
442 			return (error);
443 		}
444 		if (entry_found) {
445 			ep = (struct ext2fs_direct_2 *)((char *)bp->b_data +
446 				(entryoffsetinblock & bmask));
447 foundentry:
448 			ino = ep->e2d_ino;
449 			goto found;
450 		}
451 	}
452 notfound:
453 	/*
454 	 * If we started in the middle of the directory and failed
455 	 * to find our target, we must check the beginning as well.
456 	 */
457 	if (numdirpasses == 2) {
458 		numdirpasses--;
459 		i_offset = 0;
460 		endsearch = i_diroff;
461 		goto searchloop;
462 	}
463 	if (bp != NULL)
464 		brelse(bp);
465 	/*
466 	 * If creating, and at end of pathname and current
467 	 * directory has not been removed, then can consider
468 	 * allowing file to be created.
469 	 */
470 	if ((nameiop == CREATE || nameiop == RENAME) &&
471 	    (flags & ISLASTCN) && dp->i_nlink != 0) {
472 		/*
473 		 * Access for write is interpreted as allowing
474 		 * creation of files in the directory.
475 		 */
476 		if ((error = VOP_ACCESS(vdp, VWRITE, cred, cnp->cn_thread)) != 0)
477 			return (error);
478 		/*
479 		 * Return an indication of where the new directory
480 		 * entry should be put.  If we didn't find a slot,
481 		 * then set dp->i_count to 0 indicating
482 		 * that the new slot belongs at the end of the
483 		 * directory. If we found a slot, then the new entry
484 		 * can be put in the range from dp->i_offset to
485 		 * dp->i_offset + dp->i_count.
486 		 */
487 		if (ss.slotstatus == NONE) {
488 			dp->i_offset = roundup2(dp->i_size, DIRBLKSIZ);
489 			dp->i_count = 0;
490 			enduseful = dp->i_offset;
491 		} else {
492 			dp->i_offset = ss.slotoffset;
493 			dp->i_count = ss.slotsize;
494 			if (enduseful < ss.slotoffset + ss.slotsize)
495 				enduseful = ss.slotoffset + ss.slotsize;
496 		}
497 		dp->i_endoff = roundup2(enduseful, DIRBLKSIZ);
498 		/*
499 		 * We return with the directory locked, so that
500 		 * the parameters we set up above will still be
501 		 * valid if we actually decide to do a direnter().
502 		 * We return ni_vp == NULL to indicate that the entry
503 		 * does not currently exist; we leave a pointer to
504 		 * the (locked) directory inode in ndp->ni_dvp.
505 		 * The pathname buffer is saved so that the name
506 		 * can be obtained later.
507 		 *
508 		 * NB - if the directory is unlocked, then this
509 		 * information cannot be used.
510 		 */
511 		cnp->cn_flags |= SAVENAME;
512 		return (EJUSTRETURN);
513 	}
514 	/*
515 	 * Insert name into cache (as non-existent) if appropriate.
516 	 */
517 	if ((cnp->cn_flags & MAKEENTRY) && nameiop != CREATE)
518 		cache_enter(vdp, NULL, cnp);
519 	return (ENOENT);
520 
521 found:
522 	if (dd_ino != NULL)
523 		*dd_ino = ino;
524 	if (numdirpasses == 2)
525 		nchstats.ncs_pass2++;
526 	/*
527 	 * Check that directory length properly reflects presence
528 	 * of this entry.
529 	 */
530 	if (entryoffsetinblock + EXT2_DIR_REC_LEN(ep->e2d_namlen)
531 		> dp->i_size) {
532 		ext2_dirbad(dp, i_offset, "i_size too small");
533 		dp->i_size = entryoffsetinblock+EXT2_DIR_REC_LEN(ep->e2d_namlen);
534 		dp->i_flag |= IN_CHANGE | IN_UPDATE;
535 	}
536 	brelse(bp);
537 
538 	/*
539 	 * Found component in pathname.
540 	 * If the final component of path name, save information
541 	 * in the cache as to where the entry was found.
542 	 */
543 	if ((flags & ISLASTCN) && nameiop == LOOKUP)
544 		dp->i_diroff = i_offset &~ (DIRBLKSIZ - 1);
545 	/*
546 	 * If deleting, and at end of pathname, return
547 	 * parameters which can be used to remove file.
548 	 */
549 	if (nameiop == DELETE && (flags & ISLASTCN)) {
550 		if (flags & LOCKPARENT)
551 			ASSERT_VOP_ELOCKED(vdp, __FUNCTION__);
552 		/*
553 		 * Write access to directory required to delete files.
554 		 */
555 		if ((error = VOP_ACCESS(vdp, VWRITE, cred, cnp->cn_thread)) != 0)
556 			return (error);
557 		/*
558 		 * Return pointer to current entry in dp->i_offset,
559 		 * and distance past previous entry (if there
560 		 * is a previous entry in this block) in dp->i_count.
561 		 * Save directory inode pointer in ndp->ni_dvp for dirremove().
562 		 *
563 		 * Technically we shouldn't be setting these in the
564 		 * WANTPARENT case (first lookup in rename()), but any
565 		 * lookups that will result in directory changes will
566 		 * overwrite these.
567 		 */
568 		dp->i_offset = i_offset;
569 		if ((dp->i_offset & (DIRBLKSIZ - 1)) == 0)
570 			dp->i_count = 0;
571 		else
572 			dp->i_count = dp->i_offset - prevoff;
573 		if (dd_ino != NULL)
574 			return (0);
575 		if (dp->i_number == ino) {
576 			VREF(vdp);
577 			*vpp = vdp;
578 			return (0);
579 		}
580 		if ((error = VFS_VGET(vdp->v_mount, ino, LK_EXCLUSIVE,
581 		    &tdp)) != 0)
582 			return (error);
583 		/*
584 		 * If directory is "sticky", then user must own
585 		 * the directory, or the file in it, else she
586 		 * may not delete it (unless she's root). This
587 		 * implements append-only directories.
588 		 */
589 		if ((dp->i_mode & ISVTX) &&
590 		    cred->cr_uid != 0 &&
591 		    cred->cr_uid != dp->i_uid &&
592 		    VTOI(tdp)->i_uid != cred->cr_uid) {
593 			vput(tdp);
594 			return (EPERM);
595 		}
596 		*vpp = tdp;
597 		return (0);
598 	}
599 
600 	/*
601 	 * If rewriting (RENAME), return the inode and the
602 	 * information required to rewrite the present directory
603 	 * Must get inode of directory entry to verify it's a
604 	 * regular file, or empty directory.
605 	 */
606 	if (nameiop == RENAME && (flags & ISLASTCN)) {
607 		if ((error = VOP_ACCESS(vdp, VWRITE, cred, cnp->cn_thread)) != 0)
608 			return (error);
609 		/*
610 		 * Careful about locking second inode.
611 		 * This can only occur if the target is ".".
612 		 */
613 		dp->i_offset = i_offset;
614 		if (dp->i_number == ino)
615 			return (EISDIR);
616 		if (dd_ino != NULL)
617 			return (0);
618 		if ((error = VFS_VGET(vdp->v_mount, ino, LK_EXCLUSIVE,
619 		    &tdp)) != 0)
620 			return (error);
621 		*vpp = tdp;
622 		cnp->cn_flags |= SAVENAME;
623 		return (0);
624 	}
625 	if (dd_ino != NULL)
626 		return (0);
627 
628 	/*
629 	 * Step through the translation in the name.  We do not `vput' the
630 	 * directory because we may need it again if a symbolic link
631 	 * is relative to the current directory.  Instead we save it
632 	 * unlocked as "pdp".  We must get the target inode before unlocking
633 	 * the directory to insure that the inode will not be removed
634 	 * before we get it.  We prevent deadlock by always fetching
635 	 * inodes from the root, moving down the directory tree. Thus
636 	 * when following backward pointers ".." we must unlock the
637 	 * parent directory before getting the requested directory.
638 	 * There is a potential race condition here if both the current
639 	 * and parent directories are removed before the VFS_VGET for the
640 	 * inode associated with ".." returns.  We hope that this occurs
641 	 * infrequently since we cannot avoid this race condition without
642 	 * implementing a sophisticated deadlock detection algorithm.
643 	 * Note also that this simple deadlock detection scheme will not
644 	 * work if the file system has any hard links other than ".."
645 	 * that point backwards in the directory structure.
646 	 */
647 	pdp = vdp;
648 	if (flags & ISDOTDOT) {
649 		error = vn_vget_ino(pdp, ino, cnp->cn_lkflags, &tdp);
650 		if (pdp->v_iflag & VI_DOOMED) {
651 			if (error == 0)
652 				vput(tdp);
653 			error = ENOENT;
654 		}
655 		if (error)
656 			return (error);
657 		/*
658 		 * Recheck that ".." entry in the vdp directory points
659 		 * to the inode we looked up before vdp lock was
660 		 * dropped.
661 		 */
662 		error = ext2_lookup_ino(pdp, NULL, cnp, &ino1);
663 		if (error) {
664 			vput(tdp);
665 			return (error);
666 		}
667 		if (ino1 != ino) {
668 			vput(tdp);
669 			goto restart;
670 		}
671 		*vpp = tdp;
672 	} else if (dp->i_number == ino) {
673 		VREF(vdp);	/* we want ourself, ie "." */
674 		/*
675 		 * When we lookup "." we still can be asked to lock it
676 		 * differently.
677 		 */
678 		ltype = cnp->cn_lkflags & LK_TYPE_MASK;
679 		if (ltype != VOP_ISLOCKED(vdp)) {
680 			if (ltype == LK_EXCLUSIVE)
681 				vn_lock(vdp, LK_UPGRADE | LK_RETRY);
682 			else /* if (ltype == LK_SHARED) */
683 				vn_lock(vdp, LK_DOWNGRADE | LK_RETRY);
684 		}
685 		*vpp = vdp;
686 	} else {
687 		if ((error = VFS_VGET(vdp->v_mount, ino, cnp->cn_lkflags,
688 		    &tdp)) != 0)
689 			return (error);
690 		*vpp = tdp;
691 	}
692 
693 	/*
694 	 * Insert name into cache if appropriate.
695 	 */
696 	if (cnp->cn_flags & MAKEENTRY)
697 		cache_enter(vdp, *vpp, cnp);
698 	return (0);
699 }
700 
701 int
702 ext2_search_dirblock(struct inode *ip, void *data, int *foundp,
703 	const char *name, int namelen, int *entryoffsetinblockp,
704 	doff_t *offp, doff_t *prevoffp, doff_t *endusefulp,
705 	struct ext2fs_searchslot *ssp)
706 {
707 	struct vnode *vdp;
708 	struct ext2fs_direct_2 *ep, *top;
709 	uint32_t bsize = ip->i_e2fs->e2fs_bsize;
710 	int offset = *entryoffsetinblockp;
711 	int namlen;
712 
713 	vdp = ITOV(ip);
714 
715 	ep = (struct ext2fs_direct_2 *)((char *)data + offset);
716 	top = (struct ext2fs_direct_2 *)((char *)data +
717 		bsize - EXT2_DIR_REC_LEN(0));
718 
719 	while (ep < top) {
720 		/*
721 		 * Full validation checks are slow, so we only check
722 		 * enough to insure forward progress through the
723 		 * directory. Complete checks can be run by setting
724 		 * "vfs.e2fs.dirchk" to be true.
725 		 */
726 		if (ep->e2d_reclen == 0 ||
727 		    (dirchk && ext2_dirbadentry(vdp, ep, offset))) {
728 			int i;
729 			ext2_dirbad(ip, *offp, "mangled entry");
730 			i = bsize - (offset & (bsize - 1));
731 			*offp += i;
732 			offset += i;
733 			continue;
734 		}
735 
736 		/*
737 		 * If an appropriate sized slot has not yet been found,
738 		 * check to see if one is available. Also accumulate space
739 		 * in the current block so that we can determine if
740 		 * compaction is viable.
741 		 */
742 		if (ssp->slotstatus != FOUND) {
743 			int size = ep->e2d_reclen;
744 
745 			if (ep->e2d_ino != 0)
746 				size -= EXT2_DIR_REC_LEN(ep->e2d_namlen);
747 			if (size > 0) {
748 				if (size >= ssp->slotneeded) {
749 					ssp->slotstatus = FOUND;
750 					ssp->slotoffset = *offp;
751 					ssp->slotsize = ep->e2d_reclen;
752 				} else if (ssp->slotstatus == NONE) {
753 					ssp->slotfreespace += size;
754 					if (ssp->slotoffset == -1)
755 						ssp->slotoffset = *offp;
756 					if (ssp->slotfreespace >= ssp->slotneeded) {
757 						ssp->slotstatus = COMPACT;
758 						ssp->slotsize = *offp +
759 							ep->e2d_reclen -
760 							ssp->slotoffset;
761 					}
762 				}
763 			}
764 		}
765 
766 		/*
767 		 * Check for a name match.
768 		 */
769 		if (ep->e2d_ino) {
770 			namlen = ep->e2d_namlen;
771 			if (namlen == namelen &&
772 			    !bcmp(name, ep->e2d_name, (unsigned)namlen)) {
773 				/*
774 				 * Save directory entry's inode number and
775 				 * reclen in ndp->ni_ufs area, and release
776 				 * directory buffer.
777 				 */
778 				*foundp = 1;
779 				return (0);
780 			}
781 		}
782 		*prevoffp = *offp;
783 		*offp += ep->e2d_reclen;
784 		offset += ep->e2d_reclen;
785 		*entryoffsetinblockp = offset;
786 		if (ep->e2d_ino)
787 			*endusefulp = *offp;
788 		/*
789 		 * Get pointer to the next entry.
790 		 */
791 		ep = (struct ext2fs_direct_2 *)((char *)data + offset);
792 	}
793 
794 	return (0);
795 }
796 
797 void
798 ext2_dirbad(struct inode *ip, doff_t offset, char *how)
799 {
800 	struct mount *mp;
801 
802 	mp = ITOV(ip)->v_mount;
803 	if ((mp->mnt_flag & MNT_RDONLY) == 0)
804 		panic("ext2_dirbad: %s: bad dir ino %lu at offset %ld: %s\n",
805 			mp->mnt_stat.f_mntonname, (u_long)ip->i_number,(long)offset, how);
806 	else
807 	(void)printf("%s: bad dir ino %lu at offset %ld: %s\n",
808             mp->mnt_stat.f_mntonname, (u_long)ip->i_number, (long)offset, how);
809 
810 }
811 
812 /*
813  * Do consistency checking on a directory entry:
814  *	record length must be multiple of 4
815  *	entry must fit in rest of its DIRBLKSIZ block
816  *	record must be large enough to contain entry
817  *	name is not longer than MAXNAMLEN
818  *	name must be as long as advertised, and null terminated
819  */
820 /*
821  *	changed so that it confirms to ext2_check_dir_entry
822  */
823 static int
824 ext2_dirbadentry(struct vnode *dp, struct ext2fs_direct_2 *de,
825     int entryoffsetinblock)
826 {
827 	int	DIRBLKSIZ = VTOI(dp)->i_e2fs->e2fs_bsize;
828 
829 	char * error_msg = NULL;
830 
831 	if (de->e2d_reclen < EXT2_DIR_REC_LEN(1))
832 		error_msg = "rec_len is smaller than minimal";
833 	else if (de->e2d_reclen % 4 != 0)
834 		error_msg = "rec_len % 4 != 0";
835 	else if (de->e2d_reclen < EXT2_DIR_REC_LEN(de->e2d_namlen))
836 		error_msg = "reclen is too small for name_len";
837 	else if (entryoffsetinblock + de->e2d_reclen > DIRBLKSIZ)
838 		error_msg = "directory entry across blocks";
839 	/* else LATER
840 	     if (de->inode > dir->i_sb->u.ext2_sb.s_es->s_inodes_count)
841 		error_msg = "inode out of bounds";
842 	*/
843 
844 	if (error_msg != NULL) {
845 		printf("bad directory entry: %s\n", error_msg);
846 		printf("offset=%d, inode=%lu, rec_len=%u, name_len=%u\n",
847 			entryoffsetinblock, (unsigned long)de->e2d_ino,
848 			de->e2d_reclen, de->e2d_namlen);
849 	}
850 	return error_msg == NULL ? 0 : 1;
851 }
852 
853 /*
854  * Write a directory entry after a call to namei, using the parameters
855  * that it left in nameidata.  The argument ip is the inode which the new
856  * directory entry will refer to.  Dvp is a pointer to the directory to
857  * be written, which was left locked by namei. Remaining parameters
858  * (dp->i_offset, dp->i_count) indicate how the space for the new
859  * entry is to be obtained.
860  */
861 int
862 ext2_direnter(struct inode *ip, struct vnode *dvp, struct componentname *cnp)
863 {
864 	struct inode *dp;
865 	struct ext2fs_direct_2 newdir;
866 	struct iovec aiov;
867 	struct uio auio;
868 	int error, newentrysize;
869 	int DIRBLKSIZ = ip->i_e2fs->e2fs_bsize;
870 
871 
872 #ifdef INVARIANTS
873 	if ((cnp->cn_flags & SAVENAME) == 0)
874 		panic("ext2_direnter: missing name");
875 #endif
876 	dp = VTOI(dvp);
877 	newdir.e2d_ino = ip->i_number;
878 	newdir.e2d_namlen = cnp->cn_namelen;
879 	if (EXT2_HAS_INCOMPAT_FEATURE(ip->i_e2fs,
880 	    EXT2F_INCOMPAT_FTYPE))
881 		newdir.e2d_type = DTTOFT(IFTODT(ip->i_mode));
882 	else
883 		newdir.e2d_type = EXT2_FT_UNKNOWN;
884 	bcopy(cnp->cn_nameptr, newdir.e2d_name, (unsigned)cnp->cn_namelen + 1);
885 	newentrysize = EXT2_DIR_REC_LEN(newdir.e2d_namlen);
886 
887 #ifdef EXT2FS_HTREE
888 	if (ext2_htree_has_idx(dp)) {
889 		error = ext2_htree_add_entry(dvp, &newdir, cnp);
890 		if (error) {
891 			dp->i_flags &= ~EXT4_INDEX;
892 			dp->i_flags |= IN_CHANGE | IN_UPDATE;
893 		}
894 		return (error);
895 	}
896 
897 	if (EXT2_HAS_COMPAT_FEATURE(ip->i_e2fs, EXT2F_COMPAT_DIRHASHINDEX) &&
898 	    !ext2_htree_has_idx(dp)) {
899 		if ((dp->i_size / DIRBLKSIZ) == 1 &&
900 		    dp->i_offset == DIRBLKSIZ) {
901 			/*
902 			 * Making indexed directory when one block is not
903 			 * enough to save all entries.
904 			 */
905 			return ext2_htree_create_index(dvp, cnp, &newdir);
906 		}
907 	}
908 #endif	/* EXT2FS_HTREE */
909 
910 	if (dp->i_count == 0) {
911 		/*
912 		 * If dp->i_count is 0, then namei could find no
913 		 * space in the directory. Here, dp->i_offset will
914 		 * be on a directory block boundary and we will write the
915 		 * new entry into a fresh block.
916 		 */
917 		if (dp->i_offset & (DIRBLKSIZ - 1))
918 			panic("ext2_direnter: newblk");
919 		auio.uio_offset = dp->i_offset;
920 		newdir.e2d_reclen = DIRBLKSIZ;
921 		auio.uio_resid = newentrysize;
922 		aiov.iov_len = newentrysize;
923 		aiov.iov_base = (caddr_t)&newdir;
924 		auio.uio_iov = &aiov;
925 		auio.uio_iovcnt = 1;
926 		auio.uio_rw = UIO_WRITE;
927 		auio.uio_segflg = UIO_SYSSPACE;
928 		auio.uio_td = (struct thread *)0;
929 		error = VOP_WRITE(dvp, &auio, IO_SYNC, cnp->cn_cred);
930 		if (DIRBLKSIZ >
931 		    VFSTOEXT2(dvp->v_mount)->um_mountp->mnt_stat.f_bsize)
932 			/* XXX should grow with balloc() */
933 			panic("ext2_direnter: frag size");
934 		else if (!error) {
935 			dp->i_size = roundup2(dp->i_size, DIRBLKSIZ);
936 			dp->i_flag |= IN_CHANGE;
937 		}
938 		return (error);
939 	}
940 
941 	error = ext2_add_entry(dvp, &newdir);
942 	if (!error && dp->i_endoff && dp->i_endoff < dp->i_size)
943 		error = ext2_truncate(dvp, (off_t)dp->i_endoff, IO_SYNC,
944 		    cnp->cn_cred, cnp->cn_thread);
945 	return (error);
946 }
947 
948 /*
949  * Insert an entry into the directory block.
950  * Compact the contents.
951  */
952 int
953 ext2_add_entry(struct vnode *dvp, struct ext2fs_direct_2 *entry)
954 {
955 	struct ext2fs_direct_2 *ep, *nep;
956 	struct inode *dp;
957 	struct buf *bp;
958 	u_int dsize;
959 	int error, loc, newentrysize, spacefree;
960 	char *dirbuf;
961 
962 	dp = VTOI(dvp);
963 
964 	/*
965 	 * If dp->i_count is non-zero, then namei found space
966 	 * for the new entry in the range dp->i_offset to
967 	 * dp->i_offset + dp->i_count in the directory.
968 	 * To use this space, we may have to compact the entries located
969 	 * there, by copying them together towards the beginning of the
970 	 * block, leaving the free space in one usable chunk at the end.
971 	 */
972 
973 	/*
974 	 * Increase size of directory if entry eats into new space.
975 	 * This should never push the size past a new multiple of
976 	 * DIRBLKSIZE.
977 	 *
978 	 * N.B. - THIS IS AN ARTIFACT OF 4.2 AND SHOULD NEVER HAPPEN.
979 	 */
980 	if (dp->i_offset + dp->i_count > dp->i_size)
981 		dp->i_size = dp->i_offset + dp->i_count;
982 	/*
983 	 * Get the block containing the space for the new directory entry.
984 	 */
985 	if ((error = ext2_blkatoff(dvp, (off_t)dp->i_offset, &dirbuf,
986 	    &bp)) != 0)
987 		return (error);
988 	/*
989 	 * Find space for the new entry. In the simple case, the entry at
990 	 * offset base will have the space. If it does not, then namei
991 	 * arranged that compacting the region dp->i_offset to
992 	 * dp->i_offset + dp->i_count would yield the
993 	 * space.
994 	 */
995 	newentrysize = EXT2_DIR_REC_LEN(entry->e2d_namlen);
996 	ep = (struct ext2fs_direct_2 *)dirbuf;
997 	dsize = EXT2_DIR_REC_LEN(ep->e2d_namlen);
998 	spacefree = ep->e2d_reclen - dsize;
999 	for (loc = ep->e2d_reclen; loc < dp->i_count; ) {
1000 		nep = (struct ext2fs_direct_2 *)(dirbuf + loc);
1001 		if (ep->e2d_ino) {
1002 			/* trim the existing slot */
1003 			ep->e2d_reclen = dsize;
1004 			ep = (struct ext2fs_direct_2 *)((char *)ep + dsize);
1005 		} else {
1006 			/* overwrite; nothing there; header is ours */
1007 			spacefree += dsize;
1008 		}
1009 		dsize = EXT2_DIR_REC_LEN(nep->e2d_namlen);
1010 		spacefree += nep->e2d_reclen - dsize;
1011 		loc += nep->e2d_reclen;
1012 		bcopy((caddr_t)nep, (caddr_t)ep, dsize);
1013 	}
1014 	/*
1015 	 * Update the pointer fields in the previous entry (if any),
1016 	 * copy in the new entry, and write out the block.
1017 	 */
1018 	if (ep->e2d_ino == 0) {
1019 		if (spacefree + dsize < newentrysize)
1020 			panic("ext2_direnter: compact1");
1021 		entry->e2d_reclen = spacefree + dsize;
1022 	} else {
1023 		if (spacefree < newentrysize)
1024 			panic("ext2_direnter: compact2");
1025 		entry->e2d_reclen = spacefree;
1026 		ep->e2d_reclen = dsize;
1027 		ep = (struct ext2fs_direct_2 *)((char *)ep + dsize);
1028 	}
1029 	bcopy((caddr_t)entry, (caddr_t)ep, (u_int)newentrysize);
1030 	if (DOINGASYNC(dvp)) {
1031 		bdwrite(bp);
1032 		error = 0;
1033 	} else {
1034 		error = bwrite(bp);
1035 	}
1036 	dp->i_flag |= IN_CHANGE | IN_UPDATE;
1037 	return (error);
1038 }
1039 
1040 /*
1041  * Remove a directory entry after a call to namei, using
1042  * the parameters which it left in nameidata. The entry
1043  * dp->i_offset contains the offset into the directory of the
1044  * entry to be eliminated.  The dp->i_count field contains the
1045  * size of the previous record in the directory.  If this
1046  * is 0, the first entry is being deleted, so we need only
1047  * zero the inode number to mark the entry as free.  If the
1048  * entry is not the first in the directory, we must reclaim
1049  * the space of the now empty record by adding the record size
1050  * to the size of the previous entry.
1051  */
1052 int
1053 ext2_dirremove(struct vnode *dvp, struct componentname *cnp)
1054 {
1055 	struct inode *dp;
1056 	struct ext2fs_direct_2 *ep, *rep;
1057 	struct buf *bp;
1058 	int error;
1059 
1060 	dp = VTOI(dvp);
1061 	if (dp->i_count == 0) {
1062 		/*
1063 		 * First entry in block: set d_ino to zero.
1064 		 */
1065 		if ((error =
1066 		    ext2_blkatoff(dvp, (off_t)dp->i_offset, (char **)&ep,
1067 		    &bp)) != 0)
1068 			return (error);
1069 		ep->e2d_ino = 0;
1070 		error = bwrite(bp);
1071 		dp->i_flag |= IN_CHANGE | IN_UPDATE;
1072 		return (error);
1073 	}
1074 	/*
1075 	 * Collapse new free space into previous entry.
1076 	 */
1077 	if ((error = ext2_blkatoff(dvp, (off_t)(dp->i_offset - dp->i_count),
1078 	    (char **)&ep, &bp)) != 0)
1079 		return (error);
1080 
1081 	/* Set 'rep' to the entry being removed. */
1082 	if (dp->i_count == 0)
1083 		rep = ep;
1084 	else
1085 		rep = (struct ext2fs_direct_2 *)((char *)ep + ep->e2d_reclen);
1086 	ep->e2d_reclen += rep->e2d_reclen;
1087 	if (DOINGASYNC(dvp) && dp->i_count != 0)
1088 		bdwrite(bp);
1089 	else
1090 		error = bwrite(bp);
1091 	dp->i_flag |= IN_CHANGE | IN_UPDATE;
1092 	return (error);
1093 }
1094 
1095 /*
1096  * Rewrite an existing directory entry to point at the inode
1097  * supplied.  The parameters describing the directory entry are
1098  * set up by a call to namei.
1099  */
1100 int
1101 ext2_dirrewrite(struct inode *dp, struct inode *ip, struct componentname *cnp)
1102 {
1103 	struct buf *bp;
1104 	struct ext2fs_direct_2 *ep;
1105 	struct vnode *vdp = ITOV(dp);
1106 	int error;
1107 
1108 	if ((error = ext2_blkatoff(vdp, (off_t)dp->i_offset, (char **)&ep,
1109 	    &bp)) != 0)
1110 		return (error);
1111 	ep->e2d_ino = ip->i_number;
1112 	if (EXT2_HAS_INCOMPAT_FEATURE(ip->i_e2fs,
1113 	    EXT2F_INCOMPAT_FTYPE))
1114 		ep->e2d_type = DTTOFT(IFTODT(ip->i_mode));
1115 	else
1116 		ep->e2d_type = EXT2_FT_UNKNOWN;
1117 	error = bwrite(bp);
1118 	dp->i_flag |= IN_CHANGE | IN_UPDATE;
1119 	return (error);
1120 }
1121 
1122 /*
1123  * Check if a directory is empty or not.
1124  * Inode supplied must be locked.
1125  *
1126  * Using a struct dirtemplate here is not precisely
1127  * what we want, but better than using a struct direct.
1128  *
1129  * NB: does not handle corrupted directories.
1130  */
1131 int
1132 ext2_dirempty(struct inode *ip, ino_t parentino, struct ucred *cred)
1133 {
1134 	off_t off;
1135 	struct dirtemplate dbuf;
1136 	struct ext2fs_direct_2 *dp = (struct ext2fs_direct_2 *)&dbuf;
1137 	int error, namlen;
1138 	ssize_t count;
1139 #define	MINDIRSIZ (sizeof(struct dirtemplate) / 2)
1140 
1141 	for (off = 0; off < ip->i_size; off += dp->e2d_reclen) {
1142 		error = vn_rdwr(UIO_READ, ITOV(ip), (caddr_t)dp, MINDIRSIZ,
1143 		    off, UIO_SYSSPACE, IO_NODELOCKED | IO_NOMACCHECK, cred,
1144 		    NOCRED, &count, (struct thread *)0);
1145 		/*
1146 		 * Since we read MINDIRSIZ, residual must
1147 		 * be 0 unless we're at end of file.
1148 		 */
1149 		if (error || count != 0)
1150 			return (0);
1151 		/* avoid infinite loops */
1152 		if (dp->e2d_reclen == 0)
1153 			return (0);
1154 		/* skip empty entries */
1155 		if (dp->e2d_ino == 0)
1156 			continue;
1157 		/* accept only "." and ".." */
1158 		namlen = dp->e2d_namlen;
1159 		if (namlen > 2)
1160 			return (0);
1161 		if (dp->e2d_name[0] != '.')
1162 			return (0);
1163 		/*
1164 		 * At this point namlen must be 1 or 2.
1165 		 * 1 implies ".", 2 implies ".." if second
1166 		 * char is also "."
1167 		 */
1168 		if (namlen == 1)
1169 			continue;
1170 		if (dp->e2d_name[1] == '.' && dp->e2d_ino == parentino)
1171 			continue;
1172 		return (0);
1173 	}
1174 	return (1);
1175 }
1176 
1177 /*
1178  * Check if source directory is in the path of the target directory.
1179  * Target is supplied locked, source is unlocked.
1180  * The target is always vput before returning.
1181  */
1182 int
1183 ext2_checkpath(struct inode *source, struct inode *target, struct ucred *cred)
1184 {
1185 	struct vnode *vp;
1186 	int error, namlen;
1187 	struct dirtemplate dirbuf;
1188 
1189 	vp = ITOV(target);
1190 	if (target->i_number == source->i_number) {
1191 		error = EEXIST;
1192 		goto out;
1193 	}
1194 	if (target->i_number == EXT2_ROOTINO) {
1195 		error = 0;
1196 		goto out;
1197 	}
1198 
1199 	for (;;) {
1200 		if (vp->v_type != VDIR) {
1201 			error = ENOTDIR;
1202 			break;
1203 		}
1204 		error = vn_rdwr(UIO_READ, vp, (caddr_t)&dirbuf,
1205 			sizeof(struct dirtemplate), (off_t)0, UIO_SYSSPACE,
1206 			IO_NODELOCKED | IO_NOMACCHECK, cred, NOCRED, NULL,
1207 			NULL);
1208 		if (error != 0)
1209 			break;
1210 		namlen = dirbuf.dotdot_type;	/* like ufs little-endian */
1211 		if (namlen != 2 ||
1212 		    dirbuf.dotdot_name[0] != '.' ||
1213 		    dirbuf.dotdot_name[1] != '.') {
1214 			error = ENOTDIR;
1215 			break;
1216 		}
1217 		if (dirbuf.dotdot_ino == source->i_number) {
1218 			error = EINVAL;
1219 			break;
1220 		}
1221 		if (dirbuf.dotdot_ino == EXT2_ROOTINO)
1222 			break;
1223 		vput(vp);
1224 		if ((error = VFS_VGET(vp->v_mount, dirbuf.dotdot_ino,
1225 		    LK_EXCLUSIVE, &vp)) != 0) {
1226 			vp = NULL;
1227 			break;
1228 		}
1229 	}
1230 
1231 out:
1232 	if (error == ENOTDIR)
1233 		printf("checkpath: .. not a directory\n");
1234 	if (vp != NULL)
1235 		vput(vp);
1236 	return (error);
1237 }
1238