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1da177e4 LT |
1 | /* |
2 | * linux/fs/sysv/dir.c | |
3 | * | |
4 | * minix/dir.c | |
5 | * Copyright (C) 1991, 1992 Linus Torvalds | |
6 | * | |
7 | * coh/dir.c | |
8 | * Copyright (C) 1993 Pascal Haible, Bruno Haible | |
9 | * | |
10 | * sysv/dir.c | |
11 | * Copyright (C) 1993 Bruno Haible | |
12 | * | |
13 | * SystemV/Coherent directory handling functions | |
14 | */ | |
15 | ||
16 | #include <linux/pagemap.h> | |
17 | #include <linux/highmem.h> | |
18 | #include <linux/smp_lock.h> | |
19 | #include "sysv.h" | |
20 | ||
21 | static int sysv_readdir(struct file *, void *, filldir_t); | |
22 | ||
4b6f5d20 | 23 | const struct file_operations sysv_dir_operations = { |
1da177e4 LT |
24 | .read = generic_read_dir, |
25 | .readdir = sysv_readdir, | |
26 | .fsync = sysv_sync_file, | |
27 | }; | |
28 | ||
29 | static inline void dir_put_page(struct page *page) | |
30 | { | |
31 | kunmap(page); | |
32 | page_cache_release(page); | |
33 | } | |
34 | ||
35 | static inline unsigned long dir_pages(struct inode *inode) | |
36 | { | |
37 | return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT; | |
38 | } | |
39 | ||
40 | static int dir_commit_chunk(struct page *page, unsigned from, unsigned to) | |
41 | { | |
42 | struct inode *dir = (struct inode *)page->mapping->host; | |
43 | int err = 0; | |
44 | ||
45 | page->mapping->a_ops->commit_write(NULL, page, from, to); | |
46 | if (IS_DIRSYNC(dir)) | |
47 | err = write_one_page(page, 1); | |
48 | else | |
49 | unlock_page(page); | |
50 | return err; | |
51 | } | |
52 | ||
53 | static struct page * dir_get_page(struct inode *dir, unsigned long n) | |
54 | { | |
55 | struct address_space *mapping = dir->i_mapping; | |
090d2b18 | 56 | struct page *page = read_mapping_page(mapping, n, NULL); |
6fe6900e | 57 | if (!IS_ERR(page)) |
1da177e4 | 58 | kmap(page); |
1da177e4 | 59 | return page; |
1da177e4 LT |
60 | } |
61 | ||
62 | static int sysv_readdir(struct file * filp, void * dirent, filldir_t filldir) | |
63 | { | |
64 | unsigned long pos = filp->f_pos; | |
5495ca65 | 65 | struct inode *inode = filp->f_path.dentry->d_inode; |
1da177e4 LT |
66 | struct super_block *sb = inode->i_sb; |
67 | unsigned offset = pos & ~PAGE_CACHE_MASK; | |
68 | unsigned long n = pos >> PAGE_CACHE_SHIFT; | |
69 | unsigned long npages = dir_pages(inode); | |
70 | ||
71 | lock_kernel(); | |
72 | ||
73 | pos = (pos + SYSV_DIRSIZE-1) & ~(SYSV_DIRSIZE-1); | |
74 | if (pos >= inode->i_size) | |
75 | goto done; | |
76 | ||
77 | for ( ; n < npages; n++, offset = 0) { | |
78 | char *kaddr, *limit; | |
79 | struct sysv_dir_entry *de; | |
80 | struct page *page = dir_get_page(inode, n); | |
81 | ||
82 | if (IS_ERR(page)) | |
83 | continue; | |
84 | kaddr = (char *)page_address(page); | |
85 | de = (struct sysv_dir_entry *)(kaddr+offset); | |
86 | limit = kaddr + PAGE_CACHE_SIZE - SYSV_DIRSIZE; | |
87 | for ( ;(char*)de <= limit; de++) { | |
88 | char *name = de->name; | |
89 | int over; | |
90 | ||
91 | if (!de->inode) | |
92 | continue; | |
93 | ||
94 | offset = (char *)de - kaddr; | |
95 | ||
96 | over = filldir(dirent, name, strnlen(name,SYSV_NAMELEN), | |
54b21a79 | 97 | ((loff_t)n<<PAGE_CACHE_SHIFT) | offset, |
1da177e4 LT |
98 | fs16_to_cpu(SYSV_SB(sb), de->inode), |
99 | DT_UNKNOWN); | |
100 | if (over) { | |
101 | dir_put_page(page); | |
102 | goto done; | |
103 | } | |
104 | } | |
105 | dir_put_page(page); | |
106 | } | |
107 | ||
108 | done: | |
54b21a79 | 109 | filp->f_pos = ((loff_t)n << PAGE_CACHE_SHIFT) | offset; |
1da177e4 LT |
110 | unlock_kernel(); |
111 | return 0; | |
112 | } | |
113 | ||
114 | /* compare strings: name[0..len-1] (not zero-terminated) and | |
115 | * buffer[0..] (filled with zeroes up to buffer[0..maxlen-1]) | |
116 | */ | |
117 | static inline int namecompare(int len, int maxlen, | |
118 | const char * name, const char * buffer) | |
119 | { | |
120 | if (len < maxlen && buffer[len]) | |
121 | return 0; | |
122 | return !memcmp(name, buffer, len); | |
123 | } | |
124 | ||
125 | /* | |
126 | * sysv_find_entry() | |
127 | * | |
128 | * finds an entry in the specified directory with the wanted name. It | |
129 | * returns the cache buffer in which the entry was found, and the entry | |
130 | * itself (as a parameter - res_dir). It does NOT read the inode of the | |
131 | * entry - you'll have to do that yourself if you want to. | |
132 | */ | |
133 | struct sysv_dir_entry *sysv_find_entry(struct dentry *dentry, struct page **res_page) | |
134 | { | |
135 | const char * name = dentry->d_name.name; | |
136 | int namelen = dentry->d_name.len; | |
137 | struct inode * dir = dentry->d_parent->d_inode; | |
138 | unsigned long start, n; | |
139 | unsigned long npages = dir_pages(dir); | |
140 | struct page *page = NULL; | |
141 | struct sysv_dir_entry *de; | |
142 | ||
143 | *res_page = NULL; | |
144 | ||
145 | start = SYSV_I(dir)->i_dir_start_lookup; | |
146 | if (start >= npages) | |
147 | start = 0; | |
148 | n = start; | |
149 | ||
150 | do { | |
151 | char *kaddr; | |
152 | page = dir_get_page(dir, n); | |
153 | if (!IS_ERR(page)) { | |
154 | kaddr = (char*)page_address(page); | |
155 | de = (struct sysv_dir_entry *) kaddr; | |
156 | kaddr += PAGE_CACHE_SIZE - SYSV_DIRSIZE; | |
157 | for ( ; (char *) de <= kaddr ; de++) { | |
158 | if (!de->inode) | |
159 | continue; | |
160 | if (namecompare(namelen, SYSV_NAMELEN, | |
161 | name, de->name)) | |
162 | goto found; | |
163 | } | |
164 | } | |
165 | dir_put_page(page); | |
166 | ||
167 | if (++n >= npages) | |
168 | n = 0; | |
169 | } while (n != start); | |
170 | ||
171 | return NULL; | |
172 | ||
173 | found: | |
174 | SYSV_I(dir)->i_dir_start_lookup = n; | |
175 | *res_page = page; | |
176 | return de; | |
177 | } | |
178 | ||
179 | int sysv_add_link(struct dentry *dentry, struct inode *inode) | |
180 | { | |
181 | struct inode *dir = dentry->d_parent->d_inode; | |
182 | const char * name = dentry->d_name.name; | |
183 | int namelen = dentry->d_name.len; | |
184 | struct page *page = NULL; | |
185 | struct sysv_dir_entry * de; | |
186 | unsigned long npages = dir_pages(dir); | |
187 | unsigned long n; | |
188 | char *kaddr; | |
189 | unsigned from, to; | |
190 | int err; | |
191 | ||
192 | /* We take care of directory expansion in the same loop */ | |
193 | for (n = 0; n <= npages; n++) { | |
194 | page = dir_get_page(dir, n); | |
195 | err = PTR_ERR(page); | |
196 | if (IS_ERR(page)) | |
197 | goto out; | |
198 | kaddr = (char*)page_address(page); | |
199 | de = (struct sysv_dir_entry *)kaddr; | |
200 | kaddr += PAGE_CACHE_SIZE - SYSV_DIRSIZE; | |
201 | while ((char *)de <= kaddr) { | |
202 | if (!de->inode) | |
203 | goto got_it; | |
204 | err = -EEXIST; | |
205 | if (namecompare(namelen, SYSV_NAMELEN, name, de->name)) | |
206 | goto out_page; | |
207 | de++; | |
208 | } | |
209 | dir_put_page(page); | |
210 | } | |
211 | BUG(); | |
212 | return -EINVAL; | |
213 | ||
214 | got_it: | |
215 | from = (char*)de - (char*)page_address(page); | |
216 | to = from + SYSV_DIRSIZE; | |
217 | lock_page(page); | |
218 | err = page->mapping->a_ops->prepare_write(NULL, page, from, to); | |
219 | if (err) | |
220 | goto out_unlock; | |
221 | memcpy (de->name, name, namelen); | |
222 | memset (de->name + namelen, 0, SYSV_DIRSIZE - namelen - 2); | |
223 | de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino); | |
224 | err = dir_commit_chunk(page, from, to); | |
225 | dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC; | |
226 | mark_inode_dirty(dir); | |
227 | out_page: | |
228 | dir_put_page(page); | |
229 | out: | |
230 | return err; | |
231 | out_unlock: | |
232 | unlock_page(page); | |
233 | goto out_page; | |
234 | } | |
235 | ||
236 | int sysv_delete_entry(struct sysv_dir_entry *de, struct page *page) | |
237 | { | |
238 | struct address_space *mapping = page->mapping; | |
239 | struct inode *inode = (struct inode*)mapping->host; | |
240 | char *kaddr = (char*)page_address(page); | |
241 | unsigned from = (char*)de - kaddr; | |
242 | unsigned to = from + SYSV_DIRSIZE; | |
243 | int err; | |
244 | ||
245 | lock_page(page); | |
246 | err = mapping->a_ops->prepare_write(NULL, page, from, to); | |
d6735bfc | 247 | BUG_ON(err); |
1da177e4 LT |
248 | de->inode = 0; |
249 | err = dir_commit_chunk(page, from, to); | |
250 | dir_put_page(page); | |
251 | inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC; | |
252 | mark_inode_dirty(inode); | |
253 | return err; | |
254 | } | |
255 | ||
256 | int sysv_make_empty(struct inode *inode, struct inode *dir) | |
257 | { | |
258 | struct address_space *mapping = inode->i_mapping; | |
259 | struct page *page = grab_cache_page(mapping, 0); | |
260 | struct sysv_dir_entry * de; | |
261 | char *base; | |
262 | int err; | |
263 | ||
264 | if (!page) | |
265 | return -ENOMEM; | |
266 | kmap(page); | |
267 | err = mapping->a_ops->prepare_write(NULL, page, 0, 2 * SYSV_DIRSIZE); | |
268 | if (err) { | |
269 | unlock_page(page); | |
270 | goto fail; | |
271 | } | |
272 | ||
273 | base = (char*)page_address(page); | |
274 | memset(base, 0, PAGE_CACHE_SIZE); | |
275 | ||
276 | de = (struct sysv_dir_entry *) base; | |
277 | de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino); | |
278 | strcpy(de->name,"."); | |
279 | de++; | |
280 | de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), dir->i_ino); | |
281 | strcpy(de->name,".."); | |
282 | ||
283 | err = dir_commit_chunk(page, 0, 2 * SYSV_DIRSIZE); | |
284 | fail: | |
285 | kunmap(page); | |
286 | page_cache_release(page); | |
287 | return err; | |
288 | } | |
289 | ||
290 | /* | |
291 | * routine to check that the specified directory is empty (for rmdir) | |
292 | */ | |
293 | int sysv_empty_dir(struct inode * inode) | |
294 | { | |
295 | struct super_block *sb = inode->i_sb; | |
296 | struct page *page = NULL; | |
297 | unsigned long i, npages = dir_pages(inode); | |
298 | ||
299 | for (i = 0; i < npages; i++) { | |
300 | char *kaddr; | |
301 | struct sysv_dir_entry * de; | |
302 | page = dir_get_page(inode, i); | |
303 | ||
304 | if (IS_ERR(page)) | |
305 | continue; | |
306 | ||
307 | kaddr = (char *)page_address(page); | |
308 | de = (struct sysv_dir_entry *)kaddr; | |
309 | kaddr += PAGE_CACHE_SIZE-SYSV_DIRSIZE; | |
310 | ||
311 | for ( ;(char *)de <= kaddr; de++) { | |
312 | if (!de->inode) | |
313 | continue; | |
314 | /* check for . and .. */ | |
315 | if (de->name[0] != '.') | |
316 | goto not_empty; | |
317 | if (!de->name[1]) { | |
318 | if (de->inode == cpu_to_fs16(SYSV_SB(sb), | |
319 | inode->i_ino)) | |
320 | continue; | |
321 | goto not_empty; | |
322 | } | |
323 | if (de->name[1] != '.' || de->name[2]) | |
324 | goto not_empty; | |
325 | } | |
326 | dir_put_page(page); | |
327 | } | |
328 | return 1; | |
329 | ||
330 | not_empty: | |
331 | dir_put_page(page); | |
332 | return 0; | |
333 | } | |
334 | ||
335 | /* Releases the page */ | |
336 | void sysv_set_link(struct sysv_dir_entry *de, struct page *page, | |
337 | struct inode *inode) | |
338 | { | |
339 | struct inode *dir = (struct inode*)page->mapping->host; | |
340 | unsigned from = (char *)de-(char*)page_address(page); | |
341 | unsigned to = from + SYSV_DIRSIZE; | |
342 | int err; | |
343 | ||
344 | lock_page(page); | |
345 | err = page->mapping->a_ops->prepare_write(NULL, page, from, to); | |
d6735bfc | 346 | BUG_ON(err); |
1da177e4 LT |
347 | de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino); |
348 | err = dir_commit_chunk(page, from, to); | |
349 | dir_put_page(page); | |
350 | dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC; | |
351 | mark_inode_dirty(dir); | |
352 | } | |
353 | ||
354 | struct sysv_dir_entry * sysv_dotdot (struct inode *dir, struct page **p) | |
355 | { | |
356 | struct page *page = dir_get_page(dir, 0); | |
357 | struct sysv_dir_entry *de = NULL; | |
358 | ||
359 | if (!IS_ERR(page)) { | |
360 | de = (struct sysv_dir_entry*) page_address(page) + 1; | |
361 | *p = page; | |
362 | } | |
363 | return de; | |
364 | } | |
365 | ||
366 | ino_t sysv_inode_by_name(struct dentry *dentry) | |
367 | { | |
368 | struct page *page; | |
369 | struct sysv_dir_entry *de = sysv_find_entry (dentry, &page); | |
370 | ino_t res = 0; | |
371 | ||
372 | if (de) { | |
373 | res = fs16_to_cpu(SYSV_SB(dentry->d_sb), de->inode); | |
374 | dir_put_page(page); | |
375 | } | |
376 | return res; | |
377 | } |