File: /usr/src/linux/fs/freevxfs/vxfs_lookup.c
1 /*
2 * Copyright (c) 2000-2001 Christoph Hellwig.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions, and the following disclaimer,
10 * without modification.
11 * 2. The name of the author may not be used to endorse or promote products
12 * derived from this software without specific prior written permission.
13 *
14 * Alternatively, this software may be distributed under the terms of the
15 * GNU General Public License ("GPL").
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
21 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30 #ident "$Id: vxfs_lookup.c,v 1.19 2001/05/30 19:50:20 hch Exp hch $"
31
32 /*
33 * Veritas filesystem driver - lookup and other directory related code.
34 */
35 #include <linux/fs.h>
36 #include <linux/sched.h>
37 #include <linux/mm.h>
38 #include <linux/highmem.h>
39 #include <linux/kernel.h>
40 #include <linux/pagemap.h>
41
42 #include "vxfs.h"
43 #include "vxfs_dir.h"
44 #include "vxfs_inode.h"
45 #include "vxfs_extern.h"
46
47 /*
48 * Number of VxFS blocks per page.
49 */
50 #define VXFS_BLOCK_PER_PAGE(sbp) ((PAGE_CACHE_SIZE / (sbp)->s_blocksize))
51
52
53 static struct dentry * vxfs_lookup(struct inode *, struct dentry *);
54 static int vxfs_readdir(struct file *, void *, filldir_t);
55
56 struct inode_operations vxfs_dir_inode_ops = {
57 .lookup = vxfs_lookup,
58 };
59
60 struct file_operations vxfs_dir_operations = {
61 .readdir = vxfs_readdir,
62 };
63
64
65 static __inline__ u_long
66 dir_pages(struct inode *inode)
67 {
68 return (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
69 }
70
71 static __inline__ u_long
72 dir_blocks(struct inode *ip)
73 {
74 u_long bsize = ip->i_sb->s_blocksize;
75 return (ip->i_size + bsize - 1) & ~(bsize - 1);
76 }
77
78 /*
79 * NOTE! unlike strncmp, vxfs_match returns 1 for success, 0 for failure.
80 *
81 * len <= VXFS_NAMELEN and de != NULL are guaranteed by caller.
82 */
83 static __inline__ int
84 vxfs_match(int len, const char * const name, struct vxfs_direct *de)
85 {
86 if (len != de->d_namelen)
87 return 0;
88 if (!de->d_ino)
89 return 0;
90 return !memcmp(name, de->d_name, len);
91 }
92
93 static __inline__ struct vxfs_direct *
94 vxfs_next_entry(struct vxfs_direct *de)
95 {
96 return ((struct vxfs_direct *)((char*)de + de->d_reclen));
97 }
98
99 /**
100 * vxfs_find_entry - find a mathing directory entry for a dentry
101 * @ip: directory inode
102 * @dp: dentry for which we want to find a direct
103 * @ppp: gets filled with the page the return value sits in
104 *
105 * Description:
106 * vxfs_find_entry finds a &struct vxfs_direct for the VFS directory
107 * cache entry @dp. @ppp will be filled with the page the return
108 * value resides in.
109 *
110 * Returns:
111 * The wanted direct on success, else a NULL pointer.
112 */
113 static struct vxfs_direct *
114 vxfs_find_entry(struct inode *ip, struct dentry *dp, struct page **ppp)
115 {
116 u_long npages, page, nblocks, pblocks, block;
117 u_long bsize = ip->i_sb->s_blocksize;
118 const char *name = dp->d_name.name;
119 int namelen = dp->d_name.len;
120
121 npages = dir_pages(ip);
122 nblocks = dir_blocks(ip);
123 pblocks = VXFS_BLOCK_PER_PAGE(ip->i_sb);
124
125 for (page = 0; page < npages; page++) {
126 caddr_t kaddr;
127 struct page *pp;
128
129 pp = vxfs_get_page(ip, page);
130 if (IS_ERR(pp))
131 continue;
132 kaddr = (caddr_t)page_address(pp);
133
134 for (block = 0; block <= nblocks && block <= pblocks; block++) {
135 caddr_t baddr, limit;
136 struct vxfs_dirblk *dbp;
137 struct vxfs_direct *de;
138
139 baddr = kaddr + (block * bsize);
140 limit = baddr + bsize - VXFS_DIRLEN(1);
141
142 dbp = (struct vxfs_dirblk *)baddr;
143 de = (struct vxfs_direct *)(baddr + VXFS_DIRBLKOV(dbp));
144
145 for (; (caddr_t)de <= limit; de = vxfs_next_entry(de)) {
146 if (!de->d_reclen)
147 break;
148 if (!de->d_ino)
149 continue;
150 if (vxfs_match(namelen, name, de)) {
151 *ppp = pp;
152 return (de);
153 }
154 }
155 }
156 vxfs_put_page(pp);
157 }
158
159 return NULL;
160 }
161
162 /**
163 * vxfs_inode_by_name - find inode number for dentry
164 * @dip: directory to search in
165 * @dp: dentry we seach for
166 *
167 * Description:
168 * vxfs_inode_by_name finds out the inode number of
169 * the path component described by @dp in @dip.
170 *
171 * Returns:
172 * The wanted inode number on success, else Zero.
173 */
174 static ino_t
175 vxfs_inode_by_name(struct inode *dip, struct dentry *dp)
176 {
177 struct vxfs_direct *de;
178 struct page *pp;
179 ino_t ino = 0;
180
181 de = vxfs_find_entry(dip, dp, &pp);
182 if (de) {
183 ino = de->d_ino;
184 kunmap(pp);
185 page_cache_release(pp);
186 }
187
188 return (ino);
189 }
190
191 /**
192 * vxfs_lookup - lookup pathname component
193 * @dip: dir in which we lookup
194 * @dp: dentry we lookup
195 *
196 * Description:
197 * vxfs_lookup tries to lookup the pathname component described
198 * by @dp in @dip.
199 *
200 * Returns:
201 * A NULL-pointer on success, else an negative error code encoded
202 * in the return pointer.
203 */
204 static struct dentry *
205 vxfs_lookup(struct inode *dip, struct dentry *dp)
206 {
207 struct inode *ip = NULL;
208 ino_t ino;
209
210 if (dp->d_name.len > VXFS_NAMELEN)
211 return ERR_PTR(-ENAMETOOLONG);
212
213 ino = vxfs_inode_by_name(dip, dp);
214 if (ino == 0)
215 return NULL;
216
217 ip = iget(dip->i_sb, ino);
218 if (!ip)
219 return ERR_PTR(-EACCES);
220 d_add(dp, ip);
221 return NULL;
222 }
223
224 /**
225 * vxfs_readdir - read a directory
226 * @fp: the directory to read
227 * @retp: return buffer
228 * @filler: filldir callback
229 *
230 * Description:
231 * vxfs_readdir fills @retp with directory entries from @fp
232 * using the VFS supplied callback @filler.
233 *
234 * Returns:
235 * Zero.
236 */
237 static int
238 vxfs_readdir(struct file *fp, void *retp, filldir_t filler)
239 {
240 struct inode *ip = fp->f_dentry->d_inode;
241 struct super_block *sbp = ip->i_sb;
242 u_long bsize = sbp->s_blocksize;
243 u_long page, npages, block, pblocks, nblocks, offset;
244 loff_t pos;
245
246 switch ((long)fp->f_pos) {
247 case 0:
248 if (filler(retp, ".", 1, fp->f_pos, ip->i_ino, DT_DIR) < 0)
249 goto out;
250 fp->f_pos++;
251 /* fallthrough */
252 case 1:
253 if (filler(retp, "..", 2, fp->f_pos, VXFS_INO(ip)->vii_dotdot, DT_DIR) < 0)
254 goto out;
255 fp->f_pos++;
256 /* fallthrough */
257 }
258
259 pos = fp->f_pos - 2;
260
261 if (pos > VXFS_DIRROUND(ip->i_size))
262 return 0;
263
264 npages = dir_pages(ip);
265 nblocks = dir_blocks(ip);
266 pblocks = VXFS_BLOCK_PER_PAGE(sbp);
267
268 page = pos >> PAGE_CACHE_SHIFT;
269 offset = pos & ~PAGE_CACHE_MASK;
270 block = (u_long)(pos >> sbp->s_blocksize_bits) % pblocks;
271
272 for (; page < npages; page++, block = 0) {
273 caddr_t kaddr;
274 struct page *pp;
275
276 pp = vxfs_get_page(ip, page);
277 if (IS_ERR(pp))
278 continue;
279 kaddr = (caddr_t)page_address(pp);
280
281 for (; block <= nblocks && block <= pblocks; block++) {
282 caddr_t baddr, limit;
283 struct vxfs_dirblk *dbp;
284 struct vxfs_direct *de;
285
286 baddr = kaddr + (block * bsize);
287 limit = baddr + bsize - VXFS_DIRLEN(1);
288
289 dbp = (struct vxfs_dirblk *)baddr;
290 de = (struct vxfs_direct *)
291 (offset ?
292 (kaddr + offset) :
293 (baddr + VXFS_DIRBLKOV(dbp)));
294
295 for (; (caddr_t)de <= limit; de = vxfs_next_entry(de)) {
296 int over;
297
298 if (!de->d_reclen)
299 break;
300 if (!de->d_ino)
301 continue;
302
303 offset = (caddr_t)de - kaddr;
304 over = filler(retp, de->d_name, de->d_namelen,
305 ((page << PAGE_CACHE_SHIFT) | offset) + 2,
306 de->d_ino, DT_UNKNOWN);
307 if (over) {
308 vxfs_put_page(pp);
309 goto done;
310 }
311 }
312 offset = 0;
313 }
314 vxfs_put_page(pp);
315 offset = 0;
316 }
317
318 done:
319 fp->f_pos = ((page << PAGE_CACHE_SHIFT) | offset) + 2;
320 out:
321 fp->f_version = ip->i_version;
322 return 0;
323 }
324