blob: 732502aabc056320a714f34e2e23b0a4c555d2f6 [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
17struct file_operations minix_dir_operations = {
18 .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;
63 struct page *page = read_cache_page(mapping, n,
64 (filler_t*)mapping->a_ops->readpage, NULL);
65 if (!IS_ERR(page)) {
66 wait_on_page_locked(page);
67 kmap(page);
68 if (!PageUptodate(page))
69 goto fail;
70 }
71 return page;
72
73fail:
74 dir_put_page(page);
75 return ERR_PTR(-EIO);
76}
77
78static inline void *minix_next_entry(void *de, struct minix_sb_info *sbi)
79{
80 return (void*)((char*)de + sbi->s_dirsize);
81}
82
83static int minix_readdir(struct file * filp, void * dirent, filldir_t filldir)
84{
85 unsigned long pos = filp->f_pos;
86 struct inode *inode = filp->f_dentry->d_inode;
87 struct super_block *sb = inode->i_sb;
88 unsigned offset = pos & ~PAGE_CACHE_MASK;
89 unsigned long n = pos >> PAGE_CACHE_SHIFT;
90 unsigned long npages = dir_pages(inode);
91 struct minix_sb_info *sbi = minix_sb(sb);
92 unsigned chunk_size = sbi->s_dirsize;
93
94 lock_kernel();
95
96 pos = (pos + chunk_size-1) & ~(chunk_size-1);
97 if (pos >= inode->i_size)
98 goto done;
99
100 for ( ; n < npages; n++, offset = 0) {
101 char *p, *kaddr, *limit;
102 struct page *page = dir_get_page(inode, n);
103
104 if (IS_ERR(page))
105 continue;
106 kaddr = (char *)page_address(page);
107 p = kaddr+offset;
108 limit = kaddr + minix_last_byte(inode, n) - chunk_size;
109 for ( ; p <= limit ; p = minix_next_entry(p, sbi)) {
110 minix_dirent *de = (minix_dirent *)p;
111 if (de->inode) {
112 int over;
113 unsigned l = strnlen(de->name,sbi->s_namelen);
114
115 offset = p - kaddr;
116 over = filldir(dirent, de->name, l,
117 (n<<PAGE_CACHE_SHIFT) | offset,
118 de->inode, DT_UNKNOWN);
119 if (over) {
120 dir_put_page(page);
121 goto done;
122 }
123 }
124 }
125 dir_put_page(page);
126 }
127
128done:
129 filp->f_pos = (n << PAGE_CACHE_SHIFT) | offset;
130 unlock_kernel();
131 return 0;
132}
133
134static inline int namecompare(int len, int maxlen,
135 const char * name, const char * buffer)
136{
137 if (len < maxlen && buffer[len])
138 return 0;
139 return !memcmp(name, buffer, len);
140}
141
142/*
143 * minix_find_entry()
144 *
145 * finds an entry in the specified directory with the wanted name. It
146 * returns the cache buffer in which the entry was found, and the entry
147 * itself (as a parameter - res_dir). It does NOT read the inode of the
148 * entry - you'll have to do that yourself if you want to.
149 */
150minix_dirent *minix_find_entry(struct dentry *dentry, struct page **res_page)
151{
152 const char * name = dentry->d_name.name;
153 int namelen = dentry->d_name.len;
154 struct inode * dir = dentry->d_parent->d_inode;
155 struct super_block * sb = dir->i_sb;
156 struct minix_sb_info * sbi = minix_sb(sb);
157 unsigned long n;
158 unsigned long npages = dir_pages(dir);
159 struct page *page = NULL;
160 struct minix_dir_entry *de;
161
162 *res_page = NULL;
163
164 for (n = 0; n < npages; n++) {
165 char *kaddr;
166 page = dir_get_page(dir, n);
167 if (IS_ERR(page))
168 continue;
169
170 kaddr = (char*)page_address(page);
171 de = (struct minix_dir_entry *) kaddr;
172 kaddr += minix_last_byte(dir, n) - sbi->s_dirsize;
173 for ( ; (char *) de <= kaddr ; de = minix_next_entry(de,sbi)) {
174 if (!de->inode)
175 continue;
176 if (namecompare(namelen,sbi->s_namelen,name,de->name))
177 goto found;
178 }
179 dir_put_page(page);
180 }
181 return NULL;
182
183found:
184 *res_page = page;
185 return de;
186}
187
188int minix_add_link(struct dentry *dentry, struct inode *inode)
189{
190 struct inode *dir = dentry->d_parent->d_inode;
191 const char * name = dentry->d_name.name;
192 int namelen = dentry->d_name.len;
193 struct super_block * sb = dir->i_sb;
194 struct minix_sb_info * sbi = minix_sb(sb);
195 struct page *page = NULL;
196 struct minix_dir_entry * de;
197 unsigned long npages = dir_pages(dir);
198 unsigned long n;
199 char *kaddr;
200 unsigned from, to;
201 int err;
202
203 /*
204 * We take care of directory expansion in the same loop
205 * This code plays outside i_size, so it locks the page
206 * to protect that region.
207 */
208 for (n = 0; n <= npages; n++) {
209 char *dir_end;
210
211 page = dir_get_page(dir, n);
212 err = PTR_ERR(page);
213 if (IS_ERR(page))
214 goto out;
215 lock_page(page);
216 kaddr = (char*)page_address(page);
217 dir_end = kaddr + minix_last_byte(dir, n);
218 de = (minix_dirent *)kaddr;
219 kaddr += PAGE_CACHE_SIZE - sbi->s_dirsize;
220 while ((char *)de <= kaddr) {
221 if ((char *)de == dir_end) {
222 /* We hit i_size */
223 de->inode = 0;
224 goto got_it;
225 }
226 if (!de->inode)
227 goto got_it;
228 err = -EEXIST;
229 if (namecompare(namelen,sbi->s_namelen,name,de->name))
230 goto out_unlock;
231 de = minix_next_entry(de, sbi);
232 }
233 unlock_page(page);
234 dir_put_page(page);
235 }
236 BUG();
237 return -EINVAL;
238
239got_it:
240 from = (char*)de - (char*)page_address(page);
241 to = from + sbi->s_dirsize;
242 err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
243 if (err)
244 goto out_unlock;
245 memcpy (de->name, name, namelen);
246 memset (de->name + namelen, 0, sbi->s_dirsize - namelen - 2);
247 de->inode = inode->i_ino;
248 err = dir_commit_chunk(page, from, to);
249 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
250 mark_inode_dirty(dir);
251out_put:
252 dir_put_page(page);
253out:
254 return err;
255out_unlock:
256 unlock_page(page);
257 goto out_put;
258}
259
260int minix_delete_entry(struct minix_dir_entry *de, struct page *page)
261{
262 struct address_space *mapping = page->mapping;
263 struct inode *inode = (struct inode*)mapping->host;
264 char *kaddr = page_address(page);
265 unsigned from = (char*)de - kaddr;
266 unsigned to = from + minix_sb(inode->i_sb)->s_dirsize;
267 int err;
268
269 lock_page(page);
270 err = mapping->a_ops->prepare_write(NULL, page, from, to);
271 if (err == 0) {
272 de->inode = 0;
273 err = dir_commit_chunk(page, from, to);
274 } else {
275 unlock_page(page);
276 }
277 dir_put_page(page);
278 inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
279 mark_inode_dirty(inode);
280 return err;
281}
282
283int minix_make_empty(struct inode *inode, struct inode *dir)
284{
285 struct address_space *mapping = inode->i_mapping;
286 struct page *page = grab_cache_page(mapping, 0);
287 struct minix_sb_info * sbi = minix_sb(inode->i_sb);
288 struct minix_dir_entry * de;
289 char *kaddr;
290 int err;
291
292 if (!page)
293 return -ENOMEM;
294 err = mapping->a_ops->prepare_write(NULL, page, 0, 2 * sbi->s_dirsize);
295 if (err) {
296 unlock_page(page);
297 goto fail;
298 }
299
300 kaddr = kmap_atomic(page, KM_USER0);
301 memset(kaddr, 0, PAGE_CACHE_SIZE);
302
303 de = (struct minix_dir_entry *)kaddr;
304 de->inode = inode->i_ino;
305 strcpy(de->name,".");
306 de = minix_next_entry(de, sbi);
307 de->inode = dir->i_ino;
308 strcpy(de->name,"..");
309 kunmap_atomic(kaddr, KM_USER0);
310
311 err = dir_commit_chunk(page, 0, 2 * sbi->s_dirsize);
312fail:
313 page_cache_release(page);
314 return err;
315}
316
317/*
318 * routine to check that the specified directory is empty (for rmdir)
319 */
320int minix_empty_dir(struct inode * inode)
321{
322 struct page *page = NULL;
323 unsigned long i, npages = dir_pages(inode);
324 struct minix_sb_info *sbi = minix_sb(inode->i_sb);
325
326 for (i = 0; i < npages; i++) {
327 char *kaddr;
328 minix_dirent * de;
329 page = dir_get_page(inode, i);
330
331 if (IS_ERR(page))
332 continue;
333
334 kaddr = (char *)page_address(page);
335 de = (minix_dirent *)kaddr;
336 kaddr += minix_last_byte(inode, i) - sbi->s_dirsize;
337
338 while ((char *)de <= kaddr) {
339 if (de->inode != 0) {
340 /* check for . and .. */
341 if (de->name[0] != '.')
342 goto not_empty;
343 if (!de->name[1]) {
344 if (de->inode != inode->i_ino)
345 goto not_empty;
346 } else if (de->name[1] != '.')
347 goto not_empty;
348 else if (de->name[2])
349 goto not_empty;
350 }
351 de = minix_next_entry(de, sbi);
352 }
353 dir_put_page(page);
354 }
355 return 1;
356
357not_empty:
358 dir_put_page(page);
359 return 0;
360}
361
362/* Releases the page */
363void minix_set_link(struct minix_dir_entry *de, struct page *page,
364 struct inode *inode)
365{
366 struct inode *dir = (struct inode*)page->mapping->host;
367 struct minix_sb_info *sbi = minix_sb(dir->i_sb);
368 unsigned from = (char *)de-(char*)page_address(page);
369 unsigned to = from + sbi->s_dirsize;
370 int err;
371
372 lock_page(page);
373 err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
374 if (err == 0) {
375 de->inode = inode->i_ino;
376 err = dir_commit_chunk(page, from, to);
377 } else {
378 unlock_page(page);
379 }
380 dir_put_page(page);
381 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
382 mark_inode_dirty(dir);
383}
384
385struct minix_dir_entry * minix_dotdot (struct inode *dir, struct page **p)
386{
387 struct page *page = dir_get_page(dir, 0);
388 struct minix_sb_info *sbi = minix_sb(dir->i_sb);
389 struct minix_dir_entry *de = NULL;
390
391 if (!IS_ERR(page)) {
392 de = minix_next_entry(page_address(page), sbi);
393 *p = page;
394 }
395 return de;
396}
397
398ino_t minix_inode_by_name(struct dentry *dentry)
399{
400 struct page *page;
401 struct minix_dir_entry *de = minix_find_entry(dentry, &page);
402 ino_t res = 0;
403
404 if (de) {
405 res = de->inode;
406 dir_put_page(page);
407 }
408 return res;
409}