1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16#include <linux/pagemap.h>
17#include <linux/highmem.h>
18#include <linux/swap.h>
19#include "sysv.h"
20
21static int sysv_readdir(struct file *, struct dir_context *);
22
23const struct file_operations sysv_dir_operations = {
24 .llseek = generic_file_llseek,
25 .read = generic_read_dir,
26 .iterate = sysv_readdir,
27 .fsync = generic_file_fsync,
28};
29
30static inline void dir_put_page(struct page *page)
31{
32 kunmap(page);
33 page_cache_release(page);
34}
35
36static inline unsigned long dir_pages(struct inode *inode)
37{
38 return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
39}
40
41static 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
59static 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
68static int sysv_readdir(struct file *file, struct dir_context *ctx)
69{
70 unsigned long pos = ctx->pos;
71 struct inode *inode = file_inode(file);
72 struct super_block *sb = inode->i_sb;
73 unsigned long npages = dir_pages(inode);
74 unsigned offset;
75 unsigned long n;
76
77 ctx->pos = pos = (pos + SYSV_DIRSIZE-1) & ~(SYSV_DIRSIZE-1);
78 if (pos >= inode->i_size)
79 return 0;
80
81 offset = pos & ~PAGE_CACHE_MASK;
82 n = pos >> PAGE_CACHE_SHIFT;
83
84 for ( ; n < npages; n++, offset = 0) {
85 char *kaddr, *limit;
86 struct sysv_dir_entry *de;
87 struct page *page = dir_get_page(inode, n);
88
89 if (IS_ERR(page))
90 continue;
91 kaddr = (char *)page_address(page);
92 de = (struct sysv_dir_entry *)(kaddr+offset);
93 limit = kaddr + PAGE_CACHE_SIZE - SYSV_DIRSIZE;
94 for ( ;(char*)de <= limit; de++, ctx->pos += sizeof(*de)) {
95 char *name = de->name;
96
97 if (!de->inode)
98 continue;
99
100 if (!dir_emit(ctx, name, strnlen(name,SYSV_NAMELEN),
101 fs16_to_cpu(SYSV_SB(sb), de->inode),
102 DT_UNKNOWN)) {
103 dir_put_page(page);
104 return 0;
105 }
106 }
107 dir_put_page(page);
108 }
109 return 0;
110}
111
112
113
114
115static inline int namecompare(int len, int maxlen,
116 const char * name, const char * buffer)
117{
118 if (len < maxlen && buffer[len])
119 return 0;
120 return !memcmp(name, buffer, len);
121}
122
123
124
125
126
127
128
129
130
131struct sysv_dir_entry *sysv_find_entry(struct dentry *dentry, struct page **res_page)
132{
133 const char * name = dentry->d_name.name;
134 int namelen = dentry->d_name.len;
135 struct inode * dir = dentry->d_parent->d_inode;
136 unsigned long start, n;
137 unsigned long npages = dir_pages(dir);
138 struct page *page = NULL;
139 struct sysv_dir_entry *de;
140
141 *res_page = NULL;
142
143 start = SYSV_I(dir)->i_dir_start_lookup;
144 if (start >= npages)
145 start = 0;
146 n = start;
147
148 do {
149 char *kaddr;
150 page = dir_get_page(dir, n);
151 if (!IS_ERR(page)) {
152 kaddr = (char*)page_address(page);
153 de = (struct sysv_dir_entry *) kaddr;
154 kaddr += PAGE_CACHE_SIZE - SYSV_DIRSIZE;
155 for ( ; (char *) de <= kaddr ; de++) {
156 if (!de->inode)
157 continue;
158 if (namecompare(namelen, SYSV_NAMELEN,
159 name, de->name))
160 goto found;
161 }
162 dir_put_page(page);
163 }
164
165 if (++n >= npages)
166 n = 0;
167 } while (n != start);
168
169 return NULL;
170
171found:
172 SYSV_I(dir)->i_dir_start_lookup = n;
173 *res_page = page;
174 return de;
175}
176
177int sysv_add_link(struct dentry *dentry, struct inode *inode)
178{
179 struct inode *dir = dentry->d_parent->d_inode;
180 const char * name = dentry->d_name.name;
181 int namelen = dentry->d_name.len;
182 struct page *page = NULL;
183 struct sysv_dir_entry * de;
184 unsigned long npages = dir_pages(dir);
185 unsigned long n;
186 char *kaddr;
187 loff_t pos;
188 int err;
189
190
191 for (n = 0; n <= npages; n++) {
192 page = dir_get_page(dir, n);
193 err = PTR_ERR(page);
194 if (IS_ERR(page))
195 goto out;
196 kaddr = (char*)page_address(page);
197 de = (struct sysv_dir_entry *)kaddr;
198 kaddr += PAGE_CACHE_SIZE - SYSV_DIRSIZE;
199 while ((char *)de <= kaddr) {
200 if (!de->inode)
201 goto got_it;
202 err = -EEXIST;
203 if (namecompare(namelen, SYSV_NAMELEN, name, de->name))
204 goto out_page;
205 de++;
206 }
207 dir_put_page(page);
208 }
209 BUG();
210 return -EINVAL;
211
212got_it:
213 pos = page_offset(page) +
214 (char*)de - (char*)page_address(page);
215 lock_page(page);
216 err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
217 if (err)
218 goto out_unlock;
219 memcpy (de->name, name, namelen);
220 memset (de->name + namelen, 0, SYSV_DIRSIZE - namelen - 2);
221 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
222 err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
223 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
224 mark_inode_dirty(dir);
225out_page:
226 dir_put_page(page);
227out:
228 return err;
229out_unlock:
230 unlock_page(page);
231 goto out_page;
232}
233
234int sysv_delete_entry(struct sysv_dir_entry *de, struct page *page)
235{
236 struct inode *inode = page->mapping->host;
237 char *kaddr = (char*)page_address(page);
238 loff_t pos = page_offset(page) + (char *)de - kaddr;
239 int err;
240
241 lock_page(page);
242 err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
243 BUG_ON(err);
244 de->inode = 0;
245 err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
246 dir_put_page(page);
247 inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
248 mark_inode_dirty(inode);
249 return err;
250}
251
252int sysv_make_empty(struct inode *inode, struct inode *dir)
253{
254 struct page *page = grab_cache_page(inode->i_mapping, 0);
255 struct sysv_dir_entry * de;
256 char *base;
257 int err;
258
259 if (!page)
260 return -ENOMEM;
261 err = sysv_prepare_chunk(page, 0, 2 * SYSV_DIRSIZE);
262 if (err) {
263 unlock_page(page);
264 goto fail;
265 }
266 kmap(page);
267
268 base = (char*)page_address(page);
269 memset(base, 0, PAGE_CACHE_SIZE);
270
271 de = (struct sysv_dir_entry *) base;
272 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
273 strcpy(de->name,".");
274 de++;
275 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), dir->i_ino);
276 strcpy(de->name,"..");
277
278 kunmap(page);
279 err = dir_commit_chunk(page, 0, 2 * SYSV_DIRSIZE);
280fail:
281 page_cache_release(page);
282 return err;
283}
284
285
286
287
288int sysv_empty_dir(struct inode * inode)
289{
290 struct super_block *sb = inode->i_sb;
291 struct page *page = NULL;
292 unsigned long i, npages = dir_pages(inode);
293
294 for (i = 0; i < npages; i++) {
295 char *kaddr;
296 struct sysv_dir_entry * de;
297 page = dir_get_page(inode, i);
298
299 if (IS_ERR(page))
300 continue;
301
302 kaddr = (char *)page_address(page);
303 de = (struct sysv_dir_entry *)kaddr;
304 kaddr += PAGE_CACHE_SIZE-SYSV_DIRSIZE;
305
306 for ( ;(char *)de <= kaddr; de++) {
307 if (!de->inode)
308 continue;
309
310 if (de->name[0] != '.')
311 goto not_empty;
312 if (!de->name[1]) {
313 if (de->inode == cpu_to_fs16(SYSV_SB(sb),
314 inode->i_ino))
315 continue;
316 goto not_empty;
317 }
318 if (de->name[1] != '.' || de->name[2])
319 goto not_empty;
320 }
321 dir_put_page(page);
322 }
323 return 1;
324
325not_empty:
326 dir_put_page(page);
327 return 0;
328}
329
330
331void sysv_set_link(struct sysv_dir_entry *de, struct page *page,
332 struct inode *inode)
333{
334 struct inode *dir = page->mapping->host;
335 loff_t pos = page_offset(page) +
336 (char *)de-(char*)page_address(page);
337 int err;
338
339 lock_page(page);
340 err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
341 BUG_ON(err);
342 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
343 err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
344 dir_put_page(page);
345 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
346 mark_inode_dirty(dir);
347}
348
349struct sysv_dir_entry * sysv_dotdot (struct inode *dir, struct page **p)
350{
351 struct page *page = dir_get_page(dir, 0);
352 struct sysv_dir_entry *de = NULL;
353
354 if (!IS_ERR(page)) {
355 de = (struct sysv_dir_entry*) page_address(page) + 1;
356 *p = page;
357 }
358 return de;
359}
360
361ino_t sysv_inode_by_name(struct dentry *dentry)
362{
363 struct page *page;
364 struct sysv_dir_entry *de = sysv_find_entry (dentry, &page);
365 ino_t res = 0;
366
367 if (de) {
368 res = fs16_to_cpu(SYSV_SB(dentry->d_sb), de->inode);
369 dir_put_page(page);
370 }
371 return res;
372}
373
