1 /* $NetBSD: filecore_lookup.c,v 1.23 2024/09/08 09:36:51 rillig Exp $ */
2
3 /*-
4 * Copyright (c) 1989, 1993, 1994 The Regents of the University of California.
5 * 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 * filecore_lookup.c 1.1 1998/6/26
32 */
33
34 /*-
35 * Copyright (c) 1998 Andrew McMurry
36 *
37 * Redistribution and use in source and binary forms, with or without
38 * modification, are permitted provided that the following conditions
39 * are met:
40 * 1. Redistributions of source code must retain the above copyright
41 * notice, this list of conditions and the following disclaimer.
42 * 2. Redistributions in binary form must reproduce the above copyright
43 * notice, this list of conditions and the following disclaimer in the
44 * documentation and/or other materials provided with the distribution.
45 * 3. All advertising materials mentioning features or use of this software
46 * must display the following acknowledgement:
47 * This product includes software developed by the University of
48 * California, Berkeley and its contributors.
49 * 4. Neither the name of the University nor the names of its contributors
50 * may be used to endorse or promote products derived from this software
51 * without specific prior written permission.
52 *
53 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
54 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
55 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
56 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
57 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
58 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
59 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
60 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
61 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
62 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
63 * SUCH DAMAGE.
64 *
65 * filecore_lookup.c 1.1 1998/6/26
66 */
67
68 #include <sys/cdefs.h>
69 __KERNEL_RCSID(0, "$NetBSD: filecore_lookup.c,v 1.23 2024/09/08 09:36:51 rillig Exp $");
70
71 #include <sys/param.h>
72 #include <sys/namei.h>
73 #include <sys/buf.h>
74 #include <sys/file.h>
75 #include <sys/vnode.h>
76 #include <sys/mount.h>
77 #include <sys/systm.h>
78
79 #include <fs/filecorefs/filecore.h>
80 #include <fs/filecorefs/filecore_extern.h>
81 #include <fs/filecorefs/filecore_node.h>
82
83 /*
84 * Convert a component of a pathname into a pointer to a locked inode.
85 * This is a very central and rather complicated routine.
86 * If the file system is not maintained in a strict tree hierarchy,
87 * this can result in a deadlock situation (see comments in code below).
88 *
89 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on
90 * whether the name is to be looked up, created, renamed, or deleted.
91 * When CREATE, RENAME, or DELETE is specified, information usable in
92 * creating, renaming, or deleting a directory entry may be calculated.
93 * If flag has LOCKPARENT or'ed into it and the target of the pathname
94 * exists, lookup returns both the target and its parent directory locked.
95 * When creating or renaming and LOCKPARENT is specified, the target may
96 * not be ".". When deleting and LOCKPARENT is specified, the target may
97 * be ".", but the caller must check to ensure it does a vrele and iput
98 * instead of two iputs.
99 *
100 * Overall outline of ufs_lookup:
101 *
102 * check accessibility of directory
103 * look for name in cache, if found, then if at end of path
104 * and deleting or creating, drop it, else return name
105 * search for name in directory, to found or notfound
106 * notfound:
107 * if creating, return locked directory, leaving info on available slots
108 * else return error
109 * found:
110 * if at end of path and deleting, return information to allow delete
111 * if at end of path and rewriting (RENAME and LOCKPARENT), lock target
112 * inode and return info to allow rewrite
113 * if not at end, add name to cache; if at end and neither creating
114 * nor deleting, add name to cache
115 *
116 * NOTE: (LOOKUP | LOCKPARENT) currently returns the parent inode unlocked.
117 */
118 int
filecore_lookup(void * v)119 filecore_lookup(void *v)
120 {
121 struct vop_lookup_v2_args /* {
122 struct vnode *a_dvp;
123 struct vnode **a_vpp;
124 struct componentname *a_cnp;
125 } */ *ap = v;
126 struct vnode *vdp; /* vnode for directory being searched */
127 struct filecore_node *dp; /* inode for directory being searched */
128 struct buf *bp; /* a buffer of directory entries */
129 struct filecore_direntry *de;
130 int numdirpasses; /* strategy for directory search */
131 int error;
132 u_short namelen;
133 int res;
134 const char *name;
135 struct vnode **vpp = ap->a_vpp;
136 struct componentname *cnp = ap->a_cnp;
137 kauth_cred_t cred = cnp->cn_cred;
138 int flags;
139 int nameiop = cnp->cn_nameiop;
140 int i, endsearch;
141
142 flags = cnp->cn_flags;
143
144 bp = NULL;
145 *vpp = NULL;
146 vdp = ap->a_dvp;
147 dp = VTOI(vdp);
148
149 /*
150 * Check accessibility of directory.
151 */
152 if ((error = VOP_ACCESS(vdp, VEXEC, cred)) != 0)
153 return (error);
154
155 if ((flags & ISLASTCN) && (vdp->v_mount->mnt_flag & MNT_RDONLY) &&
156 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME))
157 return (EROFS);
158
159 /*
160 * We now have a segment name to search for, and a directory to search.
161 *
162 * Before tediously performing a linear scan of the directory,
163 * check the name cache to see if the directory/name pair
164 * we are looking for is known already.
165 */
166 if (cache_lookup(vdp, cnp->cn_nameptr, cnp->cn_namelen,
167 cnp->cn_nameiop, cnp->cn_flags, NULL, vpp)) {
168 return *vpp == NULLVP ? ENOENT : 0;
169 }
170
171 name = cnp->cn_nameptr;
172 namelen = cnp->cn_namelen;
173
174 /*
175 * If there is cached information on a previous search of
176 * this directory, pick up where we last left off.
177 * We cache only lookups as these are the most common
178 * and have the greatest payoff. Caching CREATE has little
179 * benefit as it usually must search the entire directory
180 * to determine that the entry does not exist. Caching the
181 * location of the last DELETE or RENAME has not reduced
182 * profiling time and hence has been removed in the interest
183 * of simplicity.
184 */
185 if (nameiop != LOOKUP || dp->i_diroff == 0 ||
186 dp->i_diroff >= FILECORE_MAXDIRENTS) {
187 i = 0;
188 numdirpasses = 1;
189 } else {
190 i = dp->i_diroff;
191 numdirpasses = 2;
192 namecache_count_2passes();
193 }
194 endsearch = FILECORE_MAXDIRENTS;
195
196 if ((flags & ISDOTDOT) || (name[0] == '.' && namelen == 1))
197 goto found;
198
199 error = filecore_dbread(dp, &bp);
200 if (error) {
201 return error;
202 }
203
204 de = fcdirentry(bp->b_data, i);
205
206 searchloop:
207 while (de->name[0] != 0 && i < endsearch) {
208 /*
209 * Check for a name match.
210 */
211 res = filecore_fncmp(de->name, name, namelen);
212
213 if (res == 0)
214 goto found;
215 if (res < 0)
216 goto notfound;
217
218 i++;
219 de++;
220 }
221
222 notfound:
223 /*
224 * If we started in the middle of the directory and failed
225 * to find our target, we must check the beginning as well.
226 */
227 if (numdirpasses == 2) {
228 numdirpasses--;
229 i = 0;
230 de = fcdirentry(bp->b_data, i);
231 endsearch = dp->i_diroff;
232 goto searchloop;
233 }
234 if (bp != NULL) {
235 #ifdef FILECORE_DEBUG_BR
236 printf("brelse(%p) lo1\n", bp);
237 #endif
238 brelse(bp, 0);
239 }
240
241 /*
242 * Insert name into cache (as non-existent) if appropriate.
243 */
244 cache_enter(vdp, *vpp, cnp->cn_nameptr, cnp->cn_namelen,
245 cnp->cn_flags);
246 return (nameiop == CREATE || nameiop == RENAME) ? EROFS : ENOENT;
247
248 found:
249 if (numdirpasses == 2)
250 namecache_count_pass2();
251
252 /*
253 * Found component in pathname.
254 * If the final component of path name, save information
255 * in the cache as to where the entry was found.
256 */
257 if ((flags & ISLASTCN) && nameiop == LOOKUP)
258 dp->i_diroff = i;
259
260 if (name[0] == '.' && namelen == 1) {
261 vref(vdp); /* we want ourself, ie "." */
262 *vpp = vdp;
263 } else {
264 ino_t ino;
265
266 if (flags & ISDOTDOT) {
267 ino = filecore_getparent(dp);
268 } else {
269 ino = dp->i_dirent.addr | (i << FILECORE_INO_INDEX);
270 #ifdef FILECORE_DEBUG_BR
271 printf("brelse(%p) lo4\n", bp);
272 #endif
273 brelse(bp, 0);
274 }
275 error = vcache_get(vdp->v_mount, &ino, sizeof(ino), vpp);
276 if (error)
277 return error;
278 }
279
280 /*
281 * Insert name into cache if appropriate.
282 */
283 cache_enter(vdp, *vpp, cnp->cn_nameptr, cnp->cn_namelen,
284 cnp->cn_flags);
285 return 0;
286 }
287