1 /*
2 * Copyright (c) 2000-2001 Christoph Hellwig.
3 * Copyright (c) 2016 Krzysztof Blaszkowski
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions, and the following disclaimer,
11 * without modification.
12 * 2. The name of the author may not be used to endorse or promote products
13 * derived from this software without specific prior written permission.
14 *
15 * Alternatively, this software may be distributed under the terms of the
16 * GNU General Public License ("GPL").
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
22 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31 /*
32 * Veritas filesystem driver - lookup and other directory related code.
33 */
34 #include <linux/fs.h>
35 #include <linux/time.h>
36 #include <linux/mm.h>
37 #include <linux/highmem.h>
38 #include <linux/kernel.h>
39 #include <linux/pagemap.h>
40
41 #include "vxfs.h"
42 #include "vxfs_dir.h"
43 #include "vxfs_inode.h"
44 #include "vxfs_extern.h"
45
46 /*
47 * Number of VxFS blocks per page.
48 */
49 #define VXFS_BLOCK_PER_PAGE(sbp) ((PAGE_SIZE / (sbp)->s_blocksize))
50
51
52 static struct dentry * vxfs_lookup(struct inode *, struct dentry *, unsigned int);
53 static int vxfs_readdir(struct file *, struct dir_context *);
54
55 const struct inode_operations vxfs_dir_inode_ops = {
56 .lookup = vxfs_lookup,
57 };
58
59 const struct file_operations vxfs_dir_operations = {
60 .llseek = generic_file_llseek,
61 .read = generic_read_dir,
62 .iterate_shared = vxfs_readdir,
63 };
64
65
66 /**
67 * vxfs_find_entry - find a mathing directory entry for a dentry
68 * @ip: directory inode
69 * @dp: dentry for which we want to find a direct
70 * @ppp: gets filled with the page the return value sits in
71 *
72 * Description:
73 * vxfs_find_entry finds a &struct vxfs_direct for the VFS directory
74 * cache entry @dp. @ppp will be filled with the page the return
75 * value resides in.
76 *
77 * Returns:
78 * The wanted direct on success, else a NULL pointer.
79 */
80 static struct vxfs_direct *
81 vxfs_find_entry(struct inode *ip, struct dentry *dp, struct page **ppp)
82 {
83 u_long bsize = ip->i_sb->s_blocksize;
84 const char *name = dp->d_name.name;
85 int namelen = dp->d_name.len;
86 loff_t limit = VXFS_DIRROUND(ip->i_size);
87 struct vxfs_direct *de_exit = NULL;
88 loff_t pos = 0;
89 struct vxfs_sb_info *sbi = VXFS_SBI(ip->i_sb);
90
91 while (pos < limit) {
92 struct page *pp;
93 char *kaddr;
94 int pg_ofs = pos & ~PAGE_MASK;
95
96 pp = vxfs_get_page(ip->i_mapping, pos >> PAGE_SHIFT);
97 if (IS_ERR(pp))
98 return NULL;
99 kaddr = (char *)page_address(pp);
100
101 while (pg_ofs < PAGE_SIZE && pos < limit) {
102 struct vxfs_direct *de;
103
104 if ((pos & (bsize - 1)) < 4) {
105 struct vxfs_dirblk *dbp =
106 (struct vxfs_dirblk *)
107 (kaddr + (pos & ~PAGE_MASK));
108 int overhead = VXFS_DIRBLKOV(sbi, dbp);
109
110 pos += overhead;
111 pg_ofs += overhead;
112 }
113 de = (struct vxfs_direct *)(kaddr + pg_ofs);
114
115 if (!de->d_reclen) {
116 pos += bsize - 1;
117 pos &= ~(bsize - 1);
118 break;
119 }
120
121 pg_ofs += fs16_to_cpu(sbi, de->d_reclen);
122 pos += fs16_to_cpu(sbi, de->d_reclen);
123 if (!de->d_ino)
124 continue;
125
126 if (namelen != fs16_to_cpu(sbi, de->d_namelen))
127 continue;
128 if (!memcmp(name, de->d_name, namelen)) {
129 *ppp = pp;
130 de_exit = de;
131 break;
132 }
133 }
134 if (!de_exit)
135 vxfs_put_page(pp);
136 else
137 break;
138 }
139
140 return de_exit;
141 }
142
143 /**
144 * vxfs_inode_by_name - find inode number for dentry
145 * @dip: directory to search in
146 * @dp: dentry we search for
147 *
148 * Description:
149 * vxfs_inode_by_name finds out the inode number of
150 * the path component described by @dp in @dip.
151 *
152 * Returns:
153 * The wanted inode number on success, else Zero.
154 */
155 static ino_t
156 vxfs_inode_by_name(struct inode *dip, struct dentry *dp)
157 {
158 struct vxfs_direct *de;
159 struct page *pp;
160 ino_t ino = 0;
161
162 de = vxfs_find_entry(dip, dp, &pp);
163 if (de) {
164 ino = fs32_to_cpu(VXFS_SBI(dip->i_sb), de->d_ino);
165 kunmap(pp);
166 put_page(pp);
167 }
168
169 return (ino);
170 }
171
172 /**
173 * vxfs_lookup - lookup pathname component
174 * @dip: dir in which we lookup
175 * @dp: dentry we lookup
176 * @flags: lookup flags
177 *
178 * Description:
179 * vxfs_lookup tries to lookup the pathname component described
180 * by @dp in @dip.
181 *
182 * Returns:
183 * A NULL-pointer on success, else a negative error code encoded
184 * in the return pointer.
185 */
186 static struct dentry *
187 vxfs_lookup(struct inode *dip, struct dentry *dp, unsigned int flags)
188 {
189 struct inode *ip = NULL;
190 ino_t ino;
191
192 if (dp->d_name.len > VXFS_NAMELEN)
193 return ERR_PTR(-ENAMETOOLONG);
194
195 ino = vxfs_inode_by_name(dip, dp);
196 if (ino)
197 ip = vxfs_iget(dip->i_sb, ino);
198 return d_splice_alias(ip, dp);
199 }
200
201 /**
202 * vxfs_readdir - read a directory
203 * @fp: the directory to read
204 * @retp: return buffer
205 * @filler: filldir callback
206 *
207 * Description:
208 * vxfs_readdir fills @retp with directory entries from @fp
209 * using the VFS supplied callback @filler.
210 *
211 * Returns:
212 * Zero.
213 */
214 static int
215 vxfs_readdir(struct file *fp, struct dir_context *ctx)
216 {
217 struct inode *ip = file_inode(fp);
218 struct super_block *sbp = ip->i_sb;
219 u_long bsize = sbp->s_blocksize;
220 loff_t pos, limit;
221 struct vxfs_sb_info *sbi = VXFS_SBI(sbp);
222
223 if (ctx->pos == 0) {
224 if (!dir_emit_dot(fp, ctx))
225 goto out;
226 ctx->pos++;
227 }
228 if (ctx->pos == 1) {
229 if (!dir_emit(ctx, "..", 2, VXFS_INO(ip)->vii_dotdot, DT_DIR))
230 goto out;
231 ctx->pos++;
232 }
233
234 limit = VXFS_DIRROUND(ip->i_size);
235 if (ctx->pos > limit)
236 goto out;
237
238 pos = ctx->pos & ~3L;
239
240 while (pos < limit) {
241 struct page *pp;
242 char *kaddr;
243 int pg_ofs = pos & ~PAGE_MASK;
244 int rc = 0;
245
246 pp = vxfs_get_page(ip->i_mapping, pos >> PAGE_SHIFT);
247 if (IS_ERR(pp))
248 return -ENOMEM;
249
250 kaddr = (char *)page_address(pp);
251
252 while (pg_ofs < PAGE_SIZE && pos < limit) {
253 struct vxfs_direct *de;
254
255 if ((pos & (bsize - 1)) < 4) {
256 struct vxfs_dirblk *dbp =
257 (struct vxfs_dirblk *)
258 (kaddr + (pos & ~PAGE_MASK));
259 int overhead = VXFS_DIRBLKOV(sbi, dbp);
260
261 pos += overhead;
262 pg_ofs += overhead;
263 }
264 de = (struct vxfs_direct *)(kaddr + pg_ofs);
265
266 if (!de->d_reclen) {
267 pos += bsize - 1;
268 pos &= ~(bsize - 1);
269 break;
270 }
271
272 pg_ofs += fs16_to_cpu(sbi, de->d_reclen);
273 pos += fs16_to_cpu(sbi, de->d_reclen);
274 if (!de->d_ino)
275 continue;
276
277 rc = dir_emit(ctx, de->d_name,
278 fs16_to_cpu(sbi, de->d_namelen),
279 fs32_to_cpu(sbi, de->d_ino),
280 DT_UNKNOWN);
281 if (!rc) {
282 /* the dir entry was not read, fix pos. */
283 pos -= fs16_to_cpu(sbi, de->d_reclen);
284 break;
285 }
286 }
287 vxfs_put_page(pp);
288 if (!rc)
289 break;
290 }
291
292 ctx->pos = pos | 2;
293
294 out:
295 return 0;
296 }