blob: 2b0a389d19874765585f3565102005f6facdc470 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/fs/minix/dir.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 *
6 * minix directory handling functions
7 */
8
9#include "minix.h"
10#include <linux/highmem.h>
11#include <linux/smp_lock.h>
12
13typedef struct minix_dir_entry minix_dirent;
14
15static int minix_readdir(struct file *, void *, filldir_t);
16
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -080017const struct file_operations minix_dir_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -070018 .read = generic_read_dir,
19 .readdir = minix_readdir,
20 .fsync = minix_sync_file,
21};
22
23static inline void dir_put_page(struct page *page)
24{
25 kunmap(page);
26 page_cache_release(page);
27}
28
29/*
30 * Return the offset into page `page_nr' of the last valid
31 * byte in that page, plus one.
32 */
33static unsigned
34minix_last_byte(struct inode *inode, unsigned long page_nr)
35{
36 unsigned last_byte = PAGE_CACHE_SIZE;
37
38 if (page_nr == (inode->i_size >> PAGE_CACHE_SHIFT))
39 last_byte = inode->i_size & (PAGE_CACHE_SIZE - 1);
40 return last_byte;
41}
42
43static inline unsigned long dir_pages(struct inode *inode)
44{
45 return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
46}
47
48static int dir_commit_chunk(struct page *page, unsigned from, unsigned to)
49{
50 struct inode *dir = (struct inode *)page->mapping->host;
51 int err = 0;
52 page->mapping->a_ops->commit_write(NULL, page, from, to);
53 if (IS_DIRSYNC(dir))
54 err = write_one_page(page, 1);
55 else
56 unlock_page(page);
57 return err;
58}
59
60static struct page * dir_get_page(struct inode *dir, unsigned long n)
61{
62 struct address_space *mapping = dir->i_mapping;
Pekka Enberg090d2b12006-06-23 02:05:08 -070063 struct page *page = read_mapping_page(mapping, n, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -070064 if (!IS_ERR(page)) {
65 wait_on_page_locked(page);
66 kmap(page);
67 if (!PageUptodate(page))
68 goto fail;
69 }
70 return page;
71
72fail:
73 dir_put_page(page);
74 return ERR_PTR(-EIO);
75}
76
77static inline void *minix_next_entry(void *de, struct minix_sb_info *sbi)
78{
79 return (void*)((char*)de + sbi->s_dirsize);
80}
81
82static int minix_readdir(struct file * filp, void * dirent, filldir_t filldir)
83{
84 unsigned long pos = filp->f_pos;
85 struct inode *inode = filp->f_dentry->d_inode;
86 struct super_block *sb = inode->i_sb;
87 unsigned offset = pos & ~PAGE_CACHE_MASK;
88 unsigned long n = pos >> PAGE_CACHE_SHIFT;
89 unsigned long npages = dir_pages(inode);
90 struct minix_sb_info *sbi = minix_sb(sb);
91 unsigned chunk_size = sbi->s_dirsize;
92
93 lock_kernel();
94
95 pos = (pos + chunk_size-1) & ~(chunk_size-1);
96 if (pos >= inode->i_size)
97 goto done;
98
99 for ( ; n < npages; n++, offset = 0) {
100 char *p, *kaddr, *limit;
101 struct page *page = dir_get_page(inode, n);
102
103 if (IS_ERR(page))
104 continue;
105 kaddr = (char *)page_address(page);
106 p = kaddr+offset;
107 limit = kaddr + minix_last_byte(inode, n) - chunk_size;
108 for ( ; p <= limit ; p = minix_next_entry(p, sbi)) {
109 minix_dirent *de = (minix_dirent *)p;
110 if (de->inode) {
111 int over;
112 unsigned l = strnlen(de->name,sbi->s_namelen);
113
114 offset = p - kaddr;
115 over = filldir(dirent, de->name, l,
116 (n<<PAGE_CACHE_SHIFT) | offset,
117 de->inode, DT_UNKNOWN);
118 if (over) {
119 dir_put_page(page);
120 goto done;
121 }
122 }
123 }
124 dir_put_page(page);
125 }
126
127done:
128 filp->f_pos = (n << PAGE_CACHE_SHIFT) | offset;
129 unlock_kernel();
130 return 0;
131}
132
133static inline int namecompare(int len, int maxlen,
134 const char * name, const char * buffer)
135{
136 if (len < maxlen && buffer[len])
137 return 0;
138 return !memcmp(name, buffer, len);
139}
140
141/*
142 * minix_find_entry()
143 *
144 * finds an entry in the specified directory with the wanted name. It
145 * returns the cache buffer in which the entry was found, and the entry
146 * itself (as a parameter - res_dir). It does NOT read the inode of the
147 * entry - you'll have to do that yourself if you want to.
148 */
149minix_dirent *minix_find_entry(struct dentry *dentry, struct page **res_page)
150{
151 const char * name = dentry->d_name.name;
152 int namelen = dentry->d_name.len;
153 struct inode * dir = dentry->d_parent->d_inode;
154 struct super_block * sb = dir->i_sb;
155 struct minix_sb_info * sbi = minix_sb(sb);
156 unsigned long n;
157 unsigned long npages = dir_pages(dir);
158 struct page *page = NULL;
159 struct minix_dir_entry *de;
160
161 *res_page = NULL;
162
163 for (n = 0; n < npages; n++) {
164 char *kaddr;
165 page = dir_get_page(dir, n);
166 if (IS_ERR(page))
167 continue;
168
169 kaddr = (char*)page_address(page);
170 de = (struct minix_dir_entry *) kaddr;
171 kaddr += minix_last_byte(dir, n) - sbi->s_dirsize;
172 for ( ; (char *) de <= kaddr ; de = minix_next_entry(de,sbi)) {
173 if (!de->inode)
174 continue;
175 if (namecompare(namelen,sbi->s_namelen,name,de->name))
176 goto found;
177 }
178 dir_put_page(page);
179 }
180 return NULL;
181
182found:
183 *res_page = page;
184 return de;
185}
186
187int minix_add_link(struct dentry *dentry, struct inode *inode)
188{
189 struct inode *dir = dentry->d_parent->d_inode;
190 const char * name = dentry->d_name.name;
191 int namelen = dentry->d_name.len;
192 struct super_block * sb = dir->i_sb;
193 struct minix_sb_info * sbi = minix_sb(sb);
194 struct page *page = NULL;
195 struct minix_dir_entry * de;
196 unsigned long npages = dir_pages(dir);
197 unsigned long n;
198 char *kaddr;
199 unsigned from, to;
200 int err;
201
202 /*
203 * We take care of directory expansion in the same loop
204 * This code plays outside i_size, so it locks the page
205 * to protect that region.
206 */
207 for (n = 0; n <= npages; n++) {
208 char *dir_end;
209
210 page = dir_get_page(dir, n);
211 err = PTR_ERR(page);
212 if (IS_ERR(page))
213 goto out;
214 lock_page(page);
215 kaddr = (char*)page_address(page);
216 dir_end = kaddr + minix_last_byte(dir, n);
217 de = (minix_dirent *)kaddr;
218 kaddr += PAGE_CACHE_SIZE - sbi->s_dirsize;
219 while ((char *)de <= kaddr) {
220 if ((char *)de == dir_end) {
221 /* We hit i_size */
222 de->inode = 0;
223 goto got_it;
224 }
225 if (!de->inode)
226 goto got_it;
227 err = -EEXIST;
228 if (namecompare(namelen,sbi->s_namelen,name,de->name))
229 goto out_unlock;
230 de = minix_next_entry(de, sbi);
231 }
232 unlock_page(page);
233 dir_put_page(page);
234 }
235 BUG();
236 return -EINVAL;
237
238got_it:
239 from = (char*)de - (char*)page_address(page);
240 to = from + sbi->s_dirsize;
241 err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
242 if (err)
243 goto out_unlock;
244 memcpy (de->name, name, namelen);
245 memset (de->name + namelen, 0, sbi->s_dirsize - namelen - 2);
246 de->inode = inode->i_ino;
247 err = dir_commit_chunk(page, from, to);
248 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
249 mark_inode_dirty(dir);
250out_put:
251 dir_put_page(page);
252out:
253 return err;
254out_unlock:
255 unlock_page(page);
256 goto out_put;
257}
258
259int minix_delete_entry(struct minix_dir_entry *de, struct page *page)
260{
261 struct address_space *mapping = page->mapping;
262 struct inode *inode = (struct inode*)mapping->host;
263 char *kaddr = page_address(page);
264 unsigned from = (char*)de - kaddr;
265 unsigned to = from + minix_sb(inode->i_sb)->s_dirsize;
266 int err;
267
268 lock_page(page);
269 err = mapping->a_ops->prepare_write(NULL, page, from, to);
270 if (err == 0) {
271 de->inode = 0;
272 err = dir_commit_chunk(page, from, to);
273 } else {
274 unlock_page(page);
275 }
276 dir_put_page(page);
277 inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
278 mark_inode_dirty(inode);
279 return err;
280}
281
282int minix_make_empty(struct inode *inode, struct inode *dir)
283{
284 struct address_space *mapping = inode->i_mapping;
285 struct page *page = grab_cache_page(mapping, 0);
286 struct minix_sb_info * sbi = minix_sb(inode->i_sb);
287 struct minix_dir_entry * de;
288 char *kaddr;
289 int err;
290
291 if (!page)
292 return -ENOMEM;
293 err = mapping->a_ops->prepare_write(NULL, page, 0, 2 * sbi->s_dirsize);
294 if (err) {
295 unlock_page(page);
296 goto fail;
297 }
298
299 kaddr = kmap_atomic(page, KM_USER0);
300 memset(kaddr, 0, PAGE_CACHE_SIZE);
301
302 de = (struct minix_dir_entry *)kaddr;
303 de->inode = inode->i_ino;
304 strcpy(de->name,".");
305 de = minix_next_entry(de, sbi);
306 de->inode = dir->i_ino;
307 strcpy(de->name,"..");
308 kunmap_atomic(kaddr, KM_USER0);
309
310 err = dir_commit_chunk(page, 0, 2 * sbi->s_dirsize);
311fail:
312 page_cache_release(page);
313 return err;
314}
315
316/*
317 * routine to check that the specified directory is empty (for rmdir)
318 */
319int minix_empty_dir(struct inode * inode)
320{
321 struct page *page = NULL;
322 unsigned long i, npages = dir_pages(inode);
323 struct minix_sb_info *sbi = minix_sb(inode->i_sb);
324
325 for (i = 0; i < npages; i++) {
326 char *kaddr;
327 minix_dirent * de;
328 page = dir_get_page(inode, i);
329
330 if (IS_ERR(page))
331 continue;
332
333 kaddr = (char *)page_address(page);
334 de = (minix_dirent *)kaddr;
335 kaddr += minix_last_byte(inode, i) - sbi->s_dirsize;
336
337 while ((char *)de <= kaddr) {
338 if (de->inode != 0) {
339 /* check for . and .. */
340 if (de->name[0] != '.')
341 goto not_empty;
342 if (!de->name[1]) {
343 if (de->inode != inode->i_ino)
344 goto not_empty;
345 } else if (de->name[1] != '.')
346 goto not_empty;
347 else if (de->name[2])
348 goto not_empty;
349 }
350 de = minix_next_entry(de, sbi);
351 }
352 dir_put_page(page);
353 }
354 return 1;
355
356not_empty:
357 dir_put_page(page);
358 return 0;
359}
360
361/* Releases the page */
362void minix_set_link(struct minix_dir_entry *de, struct page *page,
363 struct inode *inode)
364{
365 struct inode *dir = (struct inode*)page->mapping->host;
366 struct minix_sb_info *sbi = minix_sb(dir->i_sb);
367 unsigned from = (char *)de-(char*)page_address(page);
368 unsigned to = from + sbi->s_dirsize;
369 int err;
370
371 lock_page(page);
372 err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
373 if (err == 0) {
374 de->inode = inode->i_ino;
375 err = dir_commit_chunk(page, from, to);
376 } else {
377 unlock_page(page);
378 }
379 dir_put_page(page);
380 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
381 mark_inode_dirty(dir);
382}
383
384struct minix_dir_entry * minix_dotdot (struct inode *dir, struct page **p)
385{
386 struct page *page = dir_get_page(dir, 0);
387 struct minix_sb_info *sbi = minix_sb(dir->i_sb);
388 struct minix_dir_entry *de = NULL;
389
390 if (!IS_ERR(page)) {
391 de = minix_next_entry(page_address(page), sbi);
392 *p = page;
393 }
394 return de;
395}
396
397ino_t minix_inode_by_name(struct dentry *dentry)
398{
399 struct page *page;
400 struct minix_dir_entry *de = minix_find_entry(dentry, &page);
401 ino_t res = 0;
402
403 if (de) {
404 res = de->inode;
405 dir_put_page(page);
406 }
407 return res;
408}