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 <linux/swap.h>
20 #include "sysv.h"
21
22 static int sysv_readdir(struct file *, void *, filldir_t);
23
24 const struct file_operations sysv_dir_operations = {
25 .read = generic_read_dir,
26 .readdir = sysv_readdir,
27 .fsync = sysv_sync_file,
28 };
29
30 static inline void dir_put_page(struct page *page)
31 {
32 kunmap(page);
33 page_cache_release(page);
34 }
35
36 static inline unsigned long dir_pages(struct inode *inode)
37 {
38 return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
39 }
40
41 static int dir_commit_chunk(struct page *page, loff_t pos, unsigned len)
42 {
43 struct address_space *mapping = page->mapping;
44 struct inode *dir = mapping->host;
45 int err = 0;
46
47 block_write_end(NULL, mapping, pos, len, len, page, NULL);
48 if (pos+len > dir->i_size) {
49 i_size_write(dir, pos+len);
50 mark_inode_dirty(dir);
51 }
52 if (IS_DIRSYNC(dir))
53 err = write_one_page(page, 1);
54 else
55 unlock_page(page);
56 return err;
57 }
58
59 static struct page * dir_get_page(struct inode *dir, unsigned long n)
60 {
61 struct address_space *mapping = dir->i_mapping;
62 struct page *page = read_mapping_page(mapping, n, NULL);
63 if (!IS_ERR(page))
64 kmap(page);
65 return page;
66 }
67
68 static int sysv_readdir(struct file * filp, void * dirent, filldir_t filldir)
69 {
70 unsigned long pos = filp->f_pos;
71 struct inode *inode = filp->f_path.dentry->d_inode;
72 struct super_block *sb = inode->i_sb;
73 unsigned offset = pos & ~PAGE_CACHE_MASK;
74 unsigned long n = pos >> PAGE_CACHE_SHIFT;
75 unsigned long npages = dir_pages(inode);
76
77 lock_kernel();
78
79 pos = (pos + SYSV_DIRSIZE-1) & ~(SYSV_DIRSIZE-1);
80 if (pos >= inode->i_size)
81 goto done;
82
83 for ( ; n < npages; n++, offset = 0) {
84 char *kaddr, *limit;
85 struct sysv_dir_entry *de;
86 struct page *page = dir_get_page(inode, n);
87
88 if (IS_ERR(page))
89 continue;
90 kaddr = (char *)page_address(page);
91 de = (struct sysv_dir_entry *)(kaddr+offset);
92 limit = kaddr + PAGE_CACHE_SIZE - SYSV_DIRSIZE;
93 for ( ;(char*)de <= limit; de++) {
94 char *name = de->name;
95 int over;
96
97 if (!de->inode)
98 continue;
99
100 offset = (char *)de - kaddr;
101
102 over = filldir(dirent, name, strnlen(name,SYSV_NAMELEN),
103 ((loff_t)n<<PAGE_CACHE_SHIFT) | offset,
104 fs16_to_cpu(SYSV_SB(sb), de->inode),
105 DT_UNKNOWN);
106 if (over) {
107 dir_put_page(page);
108 goto done;
109 }
110 }
111 dir_put_page(page);
112 }
113
114 done:
115 filp->f_pos = ((loff_t)n << PAGE_CACHE_SHIFT) | offset;
116 unlock_kernel();
117 return 0;
118 }
119
120 /* compare strings: name[0..len-1] (not zero-terminated) and
121 * buffer[0..] (filled with zeroes up to buffer[0..maxlen-1])
122 */
123 static inline int namecompare(int len, int maxlen,
124 const char * name, const char * buffer)
125 {
126 if (len < maxlen && buffer[len])
127 return 0;
128 return !memcmp(name, buffer, len);
129 }
130
131 /*
132 * sysv_find_entry()
133 *
134 * finds an entry in the specified directory with the wanted name. It
135 * returns the cache buffer in which the entry was found, and the entry
136 * itself (as a parameter - res_dir). It does NOT read the inode of the
137 * entry - you'll have to do that yourself if you want to.
138 */
139 struct sysv_dir_entry *sysv_find_entry(struct dentry *dentry, struct page **res_page)
140 {
141 const char * name = dentry->d_name.name;
142 int namelen = dentry->d_name.len;
143 struct inode * dir = dentry->d_parent->d_inode;
144 unsigned long start, n;
145 unsigned long npages = dir_pages(dir);
146 struct page *page = NULL;
147 struct sysv_dir_entry *de;
148
149 *res_page = NULL;
150
151 start = SYSV_I(dir)->i_dir_start_lookup;
152 if (start >= npages)
153 start = 0;
154 n = start;
155
156 do {
157 char *kaddr;
158 page = dir_get_page(dir, n);
159 if (!IS_ERR(page)) {
160 kaddr = (char*)page_address(page);
161 de = (struct sysv_dir_entry *) kaddr;
162 kaddr += PAGE_CACHE_SIZE - SYSV_DIRSIZE;
163 for ( ; (char *) de <= kaddr ; de++) {
164 if (!de->inode)
165 continue;
166 if (namecompare(namelen, SYSV_NAMELEN,
167 name, de->name))
168 goto found;
169 }
170 }
171 dir_put_page(page);
172
173 if (++n >= npages)
174 n = 0;
175 } while (n != start);
176
177 return NULL;
178
179 found:
180 SYSV_I(dir)->i_dir_start_lookup = n;
181 *res_page = page;
182 return de;
183 }
184
185 int sysv_add_link(struct dentry *dentry, struct inode *inode)
186 {
187 struct inode *dir = dentry->d_parent->d_inode;
188 const char * name = dentry->d_name.name;
189 int namelen = dentry->d_name.len;
190 struct page *page = NULL;
191 struct sysv_dir_entry * de;
192 unsigned long npages = dir_pages(dir);
193 unsigned long n;
194 char *kaddr;
195 loff_t pos;
196 int err;
197
198 /* We take care of directory expansion in the same loop */
199 for (n = 0; n <= npages; n++) {
200 page = dir_get_page(dir, n);
201 err = PTR_ERR(page);
202 if (IS_ERR(page))
203 goto out;
204 kaddr = (char*)page_address(page);
205 de = (struct sysv_dir_entry *)kaddr;
206 kaddr += PAGE_CACHE_SIZE - SYSV_DIRSIZE;
207 while ((char *)de <= kaddr) {
208 if (!de->inode)
209 goto got_it;
210 err = -EEXIST;
211 if (namecompare(namelen, SYSV_NAMELEN, name, de->name))
212 goto out_page;
213 de++;
214 }
215 dir_put_page(page);
216 }
217 BUG();
218 return -EINVAL;
219
220 got_it:
221 pos = page_offset(page) +
222 (char*)de - (char*)page_address(page);
223 lock_page(page);
224 err = __sysv_write_begin(NULL, page->mapping, pos, SYSV_DIRSIZE,
225 AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
226 if (err)
227 goto out_unlock;
228 memcpy (de->name, name, namelen);
229 memset (de->name + namelen, 0, SYSV_DIRSIZE - namelen - 2);
230 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
231 err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
232 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
233 mark_inode_dirty(dir);
234 out_page:
235 dir_put_page(page);
236 out:
237 return err;
238 out_unlock:
239 unlock_page(page);
240 goto out_page;
241 }
242
243 int sysv_delete_entry(struct sysv_dir_entry *de, struct page *page)
244 {
245 struct address_space *mapping = page->mapping;
246 struct inode *inode = (struct inode*)mapping->host;
247 char *kaddr = (char*)page_address(page);
248 loff_t pos = page_offset(page) + (char *)de - kaddr;
249 int err;
250
251 lock_page(page);
252 err = __sysv_write_begin(NULL, mapping, pos, SYSV_DIRSIZE,
253 AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
254 BUG_ON(err);
255 de->inode = 0;
256 err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
257 dir_put_page(page);
258 inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
259 mark_inode_dirty(inode);
260 return err;
261 }
262
263 int sysv_make_empty(struct inode *inode, struct inode *dir)
264 {
265 struct address_space *mapping = inode->i_mapping;
266 struct page *page = grab_cache_page(mapping, 0);
267 struct sysv_dir_entry * de;
268 char *base;
269 int err;
270
271 if (!page)
272 return -ENOMEM;
273 err = __sysv_write_begin(NULL, mapping, 0, 2 * SYSV_DIRSIZE,
274 AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
275 if (err) {
276 unlock_page(page);
277 goto fail;
278 }
279 kmap(page);
280
281 base = (char*)page_address(page);
282 memset(base, 0, PAGE_CACHE_SIZE);
283
284 de = (struct sysv_dir_entry *) base;
285 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
286 strcpy(de->name,".");
287 de++;
288 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), dir->i_ino);
289 strcpy(de->name,"..");
290
291 kunmap(page);
292 err = dir_commit_chunk(page, 0, 2 * SYSV_DIRSIZE);
293 fail:
294 page_cache_release(page);
295 return err;
296 }
297
298 /*
299 * routine to check that the specified directory is empty (for rmdir)
300 */
301 int sysv_empty_dir(struct inode * inode)
302 {
303 struct super_block *sb = inode->i_sb;
304 struct page *page = NULL;
305 unsigned long i, npages = dir_pages(inode);
306
307 for (i = 0; i < npages; i++) {
308 char *kaddr;
309 struct sysv_dir_entry * de;
310 page = dir_get_page(inode, i);
311
312 if (IS_ERR(page))
313 continue;
314
315 kaddr = (char *)page_address(page);
316 de = (struct sysv_dir_entry *)kaddr;
317 kaddr += PAGE_CACHE_SIZE-SYSV_DIRSIZE;
318
319 for ( ;(char *)de <= kaddr; de++) {
320 if (!de->inode)
321 continue;
322 /* check for . and .. */
323 if (de->name[0] != '.')
324 goto not_empty;
325 if (!de->name[1]) {
326 if (de->inode == cpu_to_fs16(SYSV_SB(sb),
327 inode->i_ino))
328 continue;
329 goto not_empty;
330 }
331 if (de->name[1] != '.' || de->name[2])
332 goto not_empty;
333 }
334 dir_put_page(page);
335 }
336 return 1;
337
338 not_empty:
339 dir_put_page(page);
340 return 0;
341 }
342
343 /* Releases the page */
344 void sysv_set_link(struct sysv_dir_entry *de, struct page *page,
345 struct inode *inode)
346 {
347 struct address_space *mapping = page->mapping;
348 struct inode *dir = mapping->host;
349 loff_t pos = page_offset(page) +
350 (char *)de-(char*)page_address(page);
351 int err;
352
353 lock_page(page);
354 err = __sysv_write_begin(NULL, mapping, pos, SYSV_DIRSIZE,
355 AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
356 BUG_ON(err);
357 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
358 err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
359 dir_put_page(page);
360 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
361 mark_inode_dirty(dir);
362 }
363
364 struct sysv_dir_entry * sysv_dotdot (struct inode *dir, struct page **p)
365 {
366 struct page *page = dir_get_page(dir, 0);
367 struct sysv_dir_entry *de = NULL;
368
369 if (!IS_ERR(page)) {
370 de = (struct sysv_dir_entry*) page_address(page) + 1;
371 *p = page;
372 }
373 return de;
374 }
375
376 ino_t sysv_inode_by_name(struct dentry *dentry)
377 {
378 struct page *page;
379 struct sysv_dir_entry *de = sysv_find_entry (dentry, &page);
380 ino_t res = 0;
381
382 if (de) {
383 res = fs16_to_cpu(SYSV_SB(dentry->d_sb), de->inode);
384 dir_put_page(page);
385 }
386 return res;
387 }
388
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