1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * Copyright (c) 2000-2001 Christoph Hellwig. |
4 | * Copyright (c) 2016 Krzysztof Blaszkowski |
5 | */ |
6 | |
7 | /* |
8 | * Veritas filesystem driver - lookup and other directory related code. |
9 | */ |
10 | #include <linux/fs.h> |
11 | #include <linux/time.h> |
12 | #include <linux/mm.h> |
13 | #include <linux/highmem.h> |
14 | #include <linux/kernel.h> |
15 | #include <linux/pagemap.h> |
16 | |
17 | #include "vxfs.h" |
18 | #include "vxfs_dir.h" |
19 | #include "vxfs_inode.h" |
20 | #include "vxfs_extern.h" |
21 | |
22 | /* |
23 | * Number of VxFS blocks per page. |
24 | */ |
25 | #define VXFS_BLOCK_PER_PAGE(sbp) ((PAGE_SIZE / (sbp)->s_blocksize)) |
26 | |
27 | |
28 | static struct dentry * vxfs_lookup(struct inode *, struct dentry *, unsigned int); |
29 | static int vxfs_readdir(struct file *, struct dir_context *); |
30 | |
31 | const struct inode_operations vxfs_dir_inode_ops = { |
32 | .lookup = vxfs_lookup, |
33 | }; |
34 | |
35 | const struct file_operations vxfs_dir_operations = { |
36 | .llseek = generic_file_llseek, |
37 | .read = generic_read_dir, |
38 | .iterate_shared = vxfs_readdir, |
39 | }; |
40 | |
41 | |
42 | /** |
43 | * vxfs_find_entry - find a mathing directory entry for a dentry |
44 | * @ip: directory inode |
45 | * @dp: dentry for which we want to find a direct |
46 | * @ppp: gets filled with the page the return value sits in |
47 | * |
48 | * Description: |
49 | * vxfs_find_entry finds a &struct vxfs_direct for the VFS directory |
50 | * cache entry @dp. @ppp will be filled with the page the return |
51 | * value resides in. |
52 | * |
53 | * Returns: |
54 | * The wanted direct on success, else a NULL pointer. |
55 | */ |
56 | static struct vxfs_direct * |
57 | vxfs_find_entry(struct inode *ip, struct dentry *dp, struct page **ppp) |
58 | { |
59 | u_long bsize = ip->i_sb->s_blocksize; |
60 | const char *name = dp->d_name.name; |
61 | int namelen = dp->d_name.len; |
62 | loff_t limit = VXFS_DIRROUND(ip->i_size); |
63 | struct vxfs_direct *de_exit = NULL; |
64 | loff_t pos = 0; |
65 | struct vxfs_sb_info *sbi = VXFS_SBI(ip->i_sb); |
66 | |
67 | while (pos < limit) { |
68 | struct page *pp; |
69 | char *kaddr; |
70 | int pg_ofs = pos & ~PAGE_MASK; |
71 | |
72 | pp = vxfs_get_page(ip->i_mapping, pos >> PAGE_SHIFT); |
73 | if (IS_ERR(ptr: pp)) |
74 | return NULL; |
75 | kaddr = (char *)page_address(pp); |
76 | |
77 | while (pg_ofs < PAGE_SIZE && pos < limit) { |
78 | struct vxfs_direct *de; |
79 | |
80 | if ((pos & (bsize - 1)) < 4) { |
81 | struct vxfs_dirblk *dbp = |
82 | (struct vxfs_dirblk *) |
83 | (kaddr + (pos & ~PAGE_MASK)); |
84 | int overhead = VXFS_DIRBLKOV(sbi, dbp); |
85 | |
86 | pos += overhead; |
87 | pg_ofs += overhead; |
88 | } |
89 | de = (struct vxfs_direct *)(kaddr + pg_ofs); |
90 | |
91 | if (!de->d_reclen) { |
92 | pos += bsize - 1; |
93 | pos &= ~(bsize - 1); |
94 | break; |
95 | } |
96 | |
97 | pg_ofs += fs16_to_cpu(sbi, a: de->d_reclen); |
98 | pos += fs16_to_cpu(sbi, a: de->d_reclen); |
99 | if (!de->d_ino) |
100 | continue; |
101 | |
102 | if (namelen != fs16_to_cpu(sbi, a: de->d_namelen)) |
103 | continue; |
104 | if (!memcmp(p: name, q: de->d_name, size: namelen)) { |
105 | *ppp = pp; |
106 | de_exit = de; |
107 | break; |
108 | } |
109 | } |
110 | if (!de_exit) |
111 | vxfs_put_page(pp); |
112 | else |
113 | break; |
114 | } |
115 | |
116 | return de_exit; |
117 | } |
118 | |
119 | /** |
120 | * vxfs_inode_by_name - find inode number for dentry |
121 | * @dip: directory to search in |
122 | * @dp: dentry we search for |
123 | * |
124 | * Description: |
125 | * vxfs_inode_by_name finds out the inode number of |
126 | * the path component described by @dp in @dip. |
127 | * |
128 | * Returns: |
129 | * The wanted inode number on success, else Zero. |
130 | */ |
131 | static ino_t |
132 | vxfs_inode_by_name(struct inode *dip, struct dentry *dp) |
133 | { |
134 | struct vxfs_direct *de; |
135 | struct page *pp; |
136 | ino_t ino = 0; |
137 | |
138 | de = vxfs_find_entry(ip: dip, dp, ppp: &pp); |
139 | if (de) { |
140 | ino = fs32_to_cpu(VXFS_SBI(dip->i_sb), a: de->d_ino); |
141 | kunmap(page: pp); |
142 | put_page(page: pp); |
143 | } |
144 | |
145 | return (ino); |
146 | } |
147 | |
148 | /** |
149 | * vxfs_lookup - lookup pathname component |
150 | * @dip: dir in which we lookup |
151 | * @dp: dentry we lookup |
152 | * @flags: lookup flags |
153 | * |
154 | * Description: |
155 | * vxfs_lookup tries to lookup the pathname component described |
156 | * by @dp in @dip. |
157 | * |
158 | * Returns: |
159 | * A NULL-pointer on success, else a negative error code encoded |
160 | * in the return pointer. |
161 | */ |
162 | static struct dentry * |
163 | vxfs_lookup(struct inode *dip, struct dentry *dp, unsigned int flags) |
164 | { |
165 | struct inode *ip = NULL; |
166 | ino_t ino; |
167 | |
168 | if (dp->d_name.len > VXFS_NAMELEN) |
169 | return ERR_PTR(error: -ENAMETOOLONG); |
170 | |
171 | ino = vxfs_inode_by_name(dip, dp); |
172 | if (ino) |
173 | ip = vxfs_iget(dip->i_sb, ino); |
174 | return d_splice_alias(ip, dp); |
175 | } |
176 | |
177 | /** |
178 | * vxfs_readdir - read a directory |
179 | * @fp: the directory to read |
180 | * @retp: return buffer |
181 | * @filler: filldir callback |
182 | * |
183 | * Description: |
184 | * vxfs_readdir fills @retp with directory entries from @fp |
185 | * using the VFS supplied callback @filler. |
186 | * |
187 | * Returns: |
188 | * Zero. |
189 | */ |
190 | static int |
191 | vxfs_readdir(struct file *fp, struct dir_context *ctx) |
192 | { |
193 | struct inode *ip = file_inode(f: fp); |
194 | struct super_block *sbp = ip->i_sb; |
195 | u_long bsize = sbp->s_blocksize; |
196 | loff_t pos, limit; |
197 | struct vxfs_sb_info *sbi = VXFS_SBI(sbp); |
198 | |
199 | if (ctx->pos == 0) { |
200 | if (!dir_emit_dot(file: fp, ctx)) |
201 | goto out; |
202 | ctx->pos++; |
203 | } |
204 | if (ctx->pos == 1) { |
205 | if (!dir_emit(ctx, name: ".." , namelen: 2, ino: VXFS_INO(inode: ip)->vii_dotdot, DT_DIR)) |
206 | goto out; |
207 | ctx->pos++; |
208 | } |
209 | |
210 | limit = VXFS_DIRROUND(ip->i_size); |
211 | if (ctx->pos > limit) |
212 | goto out; |
213 | |
214 | pos = ctx->pos & ~3L; |
215 | |
216 | while (pos < limit) { |
217 | struct page *pp; |
218 | char *kaddr; |
219 | int pg_ofs = pos & ~PAGE_MASK; |
220 | int rc = 0; |
221 | |
222 | pp = vxfs_get_page(ip->i_mapping, pos >> PAGE_SHIFT); |
223 | if (IS_ERR(ptr: pp)) |
224 | return -ENOMEM; |
225 | |
226 | kaddr = (char *)page_address(pp); |
227 | |
228 | while (pg_ofs < PAGE_SIZE && pos < limit) { |
229 | struct vxfs_direct *de; |
230 | |
231 | if ((pos & (bsize - 1)) < 4) { |
232 | struct vxfs_dirblk *dbp = |
233 | (struct vxfs_dirblk *) |
234 | (kaddr + (pos & ~PAGE_MASK)); |
235 | int overhead = VXFS_DIRBLKOV(sbi, dbp); |
236 | |
237 | pos += overhead; |
238 | pg_ofs += overhead; |
239 | } |
240 | de = (struct vxfs_direct *)(kaddr + pg_ofs); |
241 | |
242 | if (!de->d_reclen) { |
243 | pos += bsize - 1; |
244 | pos &= ~(bsize - 1); |
245 | break; |
246 | } |
247 | |
248 | pg_ofs += fs16_to_cpu(sbi, a: de->d_reclen); |
249 | pos += fs16_to_cpu(sbi, a: de->d_reclen); |
250 | if (!de->d_ino) |
251 | continue; |
252 | |
253 | rc = dir_emit(ctx, name: de->d_name, |
254 | namelen: fs16_to_cpu(sbi, a: de->d_namelen), |
255 | ino: fs32_to_cpu(sbi, a: de->d_ino), |
256 | DT_UNKNOWN); |
257 | if (!rc) { |
258 | /* the dir entry was not read, fix pos. */ |
259 | pos -= fs16_to_cpu(sbi, a: de->d_reclen); |
260 | break; |
261 | } |
262 | } |
263 | vxfs_put_page(pp); |
264 | if (!rc) |
265 | break; |
266 | } |
267 | |
268 | ctx->pos = pos | 2; |
269 | |
270 | out: |
271 | return 0; |
272 | } |
273 | |