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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/swap.h>
19#include "sysv.h"
20
21static int sysv_readdir(struct file *, void *, filldir_t);
22
23const struct file_operations sysv_dir_operations = {
24 .llseek = generic_file_llseek,
25 .read = generic_read_dir,
26 .readdir = 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 * 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 pos = (pos + SYSV_DIRSIZE-1) & ~(SYSV_DIRSIZE-1);
78 if (pos >= inode->i_size)
79 goto done;
80
81 for ( ; n < npages; n++, offset = 0) {
82 char *kaddr, *limit;
83 struct sysv_dir_entry *de;
84 struct page *page = dir_get_page(inode, n);
85
86 if (IS_ERR(page))
87 continue;
88 kaddr = (char *)page_address(page);
89 de = (struct sysv_dir_entry *)(kaddr+offset);
90 limit = kaddr + PAGE_CACHE_SIZE - SYSV_DIRSIZE;
91 for ( ;(char*)de <= limit; de++) {
92 char *name = de->name;
93 int over;
94
95 if (!de->inode)
96 continue;
97
98 offset = (char *)de - kaddr;
99
100 over = filldir(dirent, name, strnlen(name,SYSV_NAMELEN),
101 ((loff_t)n<<PAGE_CACHE_SHIFT) | offset,
102 fs16_to_cpu(SYSV_SB(sb), de->inode),
103 DT_UNKNOWN);
104 if (over) {
105 dir_put_page(page);
106 goto done;
107 }
108 }
109 dir_put_page(page);
110 }
111
112done:
113 filp->f_pos = ((loff_t)n << PAGE_CACHE_SHIFT) | offset;
114 return 0;
115}
116
117/* compare strings: name[0..len-1] (not zero-terminated) and
118 * buffer[0..] (filled with zeroes up to buffer[0..maxlen-1])
119 */
120static inline int namecompare(int len, int maxlen,
121 const char * name, const char * buffer)
122{
123 if (len < maxlen && buffer[len])
124 return 0;
125 return !memcmp(name, buffer, len);
126}
127
128/*
129 * sysv_find_entry()
130 *
131 * finds an entry in the specified directory with the wanted name. It
132 * returns the cache buffer in which the entry was found, and the entry
133 * itself (as a parameter - res_dir). It does NOT read the inode of the
134 * entry - you'll have to do that yourself if you want to.
135 */
136struct sysv_dir_entry *sysv_find_entry(struct dentry *dentry, struct page **res_page)
137{
138 const char * name = dentry->d_name.name;
139 int namelen = dentry->d_name.len;
140 struct inode * dir = dentry->d_parent->d_inode;
141 unsigned long start, n;
142 unsigned long npages = dir_pages(dir);
143 struct page *page = NULL;
144 struct sysv_dir_entry *de;
145
146 *res_page = NULL;
147
148 start = SYSV_I(dir)->i_dir_start_lookup;
149 if (start >= npages)
150 start = 0;
151 n = start;
152
153 do {
154 char *kaddr;
155 page = dir_get_page(dir, n);
156 if (!IS_ERR(page)) {
157 kaddr = (char*)page_address(page);
158 de = (struct sysv_dir_entry *) kaddr;
159 kaddr += PAGE_CACHE_SIZE - SYSV_DIRSIZE;
160 for ( ; (char *) de <= kaddr ; de++) {
161 if (!de->inode)
162 continue;
163 if (namecompare(namelen, SYSV_NAMELEN,
164 name, de->name))
165 goto found;
166 }
167 dir_put_page(page);
168 }
169
170 if (++n >= npages)
171 n = 0;
172 } while (n != start);
173
174 return NULL;
175
176found:
177 SYSV_I(dir)->i_dir_start_lookup = n;
178 *res_page = page;
179 return de;
180}
181
182int sysv_add_link(struct dentry *dentry, struct inode *inode)
183{
184 struct inode *dir = dentry->d_parent->d_inode;
185 const char * name = dentry->d_name.name;
186 int namelen = dentry->d_name.len;
187 struct page *page = NULL;
188 struct sysv_dir_entry * de;
189 unsigned long npages = dir_pages(dir);
190 unsigned long n;
191 char *kaddr;
192 loff_t pos;
193 int err;
194
195 /* We take care of directory expansion in the same loop */
196 for (n = 0; n <= npages; n++) {
197 page = dir_get_page(dir, n);
198 err = PTR_ERR(page);
199 if (IS_ERR(page))
200 goto out;
201 kaddr = (char*)page_address(page);
202 de = (struct sysv_dir_entry *)kaddr;
203 kaddr += PAGE_CACHE_SIZE - SYSV_DIRSIZE;
204 while ((char *)de <= kaddr) {
205 if (!de->inode)
206 goto got_it;
207 err = -EEXIST;
208 if (namecompare(namelen, SYSV_NAMELEN, name, de->name))
209 goto out_page;
210 de++;
211 }
212 dir_put_page(page);
213 }
214 BUG();
215 return -EINVAL;
216
217got_it:
218 pos = page_offset(page) +
219 (char*)de - (char*)page_address(page);
220 lock_page(page);
221 err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
222 if (err)
223 goto out_unlock;
224 memcpy (de->name, name, namelen);
225 memset (de->name + namelen, 0, SYSV_DIRSIZE - namelen - 2);
226 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
227 err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
228 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
229 mark_inode_dirty(dir);
230out_page:
231 dir_put_page(page);
232out:
233 return err;
234out_unlock:
235 unlock_page(page);
236 goto out_page;
237}
238
239int sysv_delete_entry(struct sysv_dir_entry *de, struct page *page)
240{
241 struct inode *inode = page->mapping->host;
242 char *kaddr = (char*)page_address(page);
243 loff_t pos = page_offset(page) + (char *)de - kaddr;
244 int err;
245
246 lock_page(page);
247 err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
248 BUG_ON(err);
249 de->inode = 0;
250 err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
251 dir_put_page(page);
252 inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
253 mark_inode_dirty(inode);
254 return err;
255}
256
257int sysv_make_empty(struct inode *inode, struct inode *dir)
258{
259 struct page *page = grab_cache_page(inode->i_mapping, 0);
260 struct sysv_dir_entry * de;
261 char *base;
262 int err;
263
264 if (!page)
265 return -ENOMEM;
266 err = sysv_prepare_chunk(page, 0, 2 * SYSV_DIRSIZE);
267 if (err) {
268 unlock_page(page);
269 goto fail;
270 }
271 kmap(page);
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 kunmap(page);
284 err = dir_commit_chunk(page, 0, 2 * SYSV_DIRSIZE);
285fail:
286 page_cache_release(page);
287 return err;
288}
289
290/*
291 * routine to check that the specified directory is empty (for rmdir)
292 */
293int 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
330not_empty:
331 dir_put_page(page);
332 return 0;
333}
334
335/* Releases the page */
336void sysv_set_link(struct sysv_dir_entry *de, struct page *page,
337 struct inode *inode)
338{
339 struct inode *dir = page->mapping->host;
340 loff_t pos = page_offset(page) +
341 (char *)de-(char*)page_address(page);
342 int err;
343
344 lock_page(page);
345 err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
346 BUG_ON(err);
347 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
348 err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
349 dir_put_page(page);
350 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
351 mark_inode_dirty(dir);
352}
353
354struct 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
366ino_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}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/fs/sysv/dir.c
4 *
5 * minix/dir.c
6 * Copyright (C) 1991, 1992 Linus Torvalds
7 *
8 * coh/dir.c
9 * Copyright (C) 1993 Pascal Haible, Bruno Haible
10 *
11 * sysv/dir.c
12 * Copyright (C) 1993 Bruno Haible
13 *
14 * SystemV/Coherent directory handling functions
15 */
16
17#include <linux/pagemap.h>
18#include <linux/highmem.h>
19#include <linux/swap.h>
20#include "sysv.h"
21
22static int sysv_readdir(struct file *, struct dir_context *);
23
24const struct file_operations sysv_dir_operations = {
25 .llseek = generic_file_llseek,
26 .read = generic_read_dir,
27 .iterate_shared = sysv_readdir,
28 .fsync = generic_file_fsync,
29};
30
31static inline void dir_put_page(struct page *page)
32{
33 kunmap(page);
34 put_page(page);
35}
36
37static int dir_commit_chunk(struct page *page, loff_t pos, unsigned len)
38{
39 struct address_space *mapping = page->mapping;
40 struct inode *dir = mapping->host;
41 int err = 0;
42
43 block_write_end(NULL, mapping, pos, len, len, page, NULL);
44 if (pos+len > dir->i_size) {
45 i_size_write(dir, pos+len);
46 mark_inode_dirty(dir);
47 }
48 if (IS_DIRSYNC(dir))
49 err = write_one_page(page);
50 else
51 unlock_page(page);
52 return err;
53}
54
55static struct page * dir_get_page(struct inode *dir, unsigned long n)
56{
57 struct address_space *mapping = dir->i_mapping;
58 struct page *page = read_mapping_page(mapping, n, NULL);
59 if (!IS_ERR(page))
60 kmap(page);
61 return page;
62}
63
64static int sysv_readdir(struct file *file, struct dir_context *ctx)
65{
66 unsigned long pos = ctx->pos;
67 struct inode *inode = file_inode(file);
68 struct super_block *sb = inode->i_sb;
69 unsigned long npages = dir_pages(inode);
70 unsigned offset;
71 unsigned long n;
72
73 ctx->pos = pos = (pos + SYSV_DIRSIZE-1) & ~(SYSV_DIRSIZE-1);
74 if (pos >= inode->i_size)
75 return 0;
76
77 offset = pos & ~PAGE_MASK;
78 n = pos >> PAGE_SHIFT;
79
80 for ( ; n < npages; n++, offset = 0) {
81 char *kaddr, *limit;
82 struct sysv_dir_entry *de;
83 struct page *page = dir_get_page(inode, n);
84
85 if (IS_ERR(page))
86 continue;
87 kaddr = (char *)page_address(page);
88 de = (struct sysv_dir_entry *)(kaddr+offset);
89 limit = kaddr + PAGE_SIZE - SYSV_DIRSIZE;
90 for ( ;(char*)de <= limit; de++, ctx->pos += sizeof(*de)) {
91 char *name = de->name;
92
93 if (!de->inode)
94 continue;
95
96 if (!dir_emit(ctx, name, strnlen(name,SYSV_NAMELEN),
97 fs16_to_cpu(SYSV_SB(sb), de->inode),
98 DT_UNKNOWN)) {
99 dir_put_page(page);
100 return 0;
101 }
102 }
103 dir_put_page(page);
104 }
105 return 0;
106}
107
108/* compare strings: name[0..len-1] (not zero-terminated) and
109 * buffer[0..] (filled with zeroes up to buffer[0..maxlen-1])
110 */
111static inline int namecompare(int len, int maxlen,
112 const char * name, const char * buffer)
113{
114 if (len < maxlen && buffer[len])
115 return 0;
116 return !memcmp(name, buffer, len);
117}
118
119/*
120 * sysv_find_entry()
121 *
122 * finds an entry in the specified directory with the wanted name. It
123 * returns the cache buffer in which the entry was found, and the entry
124 * itself (as a parameter - res_dir). It does NOT read the inode of the
125 * entry - you'll have to do that yourself if you want to.
126 */
127struct sysv_dir_entry *sysv_find_entry(struct dentry *dentry, struct page **res_page)
128{
129 const char * name = dentry->d_name.name;
130 int namelen = dentry->d_name.len;
131 struct inode * dir = d_inode(dentry->d_parent);
132 unsigned long start, n;
133 unsigned long npages = dir_pages(dir);
134 struct page *page = NULL;
135 struct sysv_dir_entry *de;
136
137 *res_page = NULL;
138
139 start = SYSV_I(dir)->i_dir_start_lookup;
140 if (start >= npages)
141 start = 0;
142 n = start;
143
144 do {
145 char *kaddr;
146 page = dir_get_page(dir, n);
147 if (!IS_ERR(page)) {
148 kaddr = (char*)page_address(page);
149 de = (struct sysv_dir_entry *) kaddr;
150 kaddr += PAGE_SIZE - SYSV_DIRSIZE;
151 for ( ; (char *) de <= kaddr ; de++) {
152 if (!de->inode)
153 continue;
154 if (namecompare(namelen, SYSV_NAMELEN,
155 name, de->name))
156 goto found;
157 }
158 dir_put_page(page);
159 }
160
161 if (++n >= npages)
162 n = 0;
163 } while (n != start);
164
165 return NULL;
166
167found:
168 SYSV_I(dir)->i_dir_start_lookup = n;
169 *res_page = page;
170 return de;
171}
172
173int sysv_add_link(struct dentry *dentry, struct inode *inode)
174{
175 struct inode *dir = d_inode(dentry->d_parent);
176 const char * name = dentry->d_name.name;
177 int namelen = dentry->d_name.len;
178 struct page *page = NULL;
179 struct sysv_dir_entry * de;
180 unsigned long npages = dir_pages(dir);
181 unsigned long n;
182 char *kaddr;
183 loff_t pos;
184 int err;
185
186 /* We take care of directory expansion in the same loop */
187 for (n = 0; n <= npages; n++) {
188 page = dir_get_page(dir, n);
189 err = PTR_ERR(page);
190 if (IS_ERR(page))
191 goto out;
192 kaddr = (char*)page_address(page);
193 de = (struct sysv_dir_entry *)kaddr;
194 kaddr += PAGE_SIZE - SYSV_DIRSIZE;
195 while ((char *)de <= kaddr) {
196 if (!de->inode)
197 goto got_it;
198 err = -EEXIST;
199 if (namecompare(namelen, SYSV_NAMELEN, name, de->name))
200 goto out_page;
201 de++;
202 }
203 dir_put_page(page);
204 }
205 BUG();
206 return -EINVAL;
207
208got_it:
209 pos = page_offset(page) +
210 (char*)de - (char*)page_address(page);
211 lock_page(page);
212 err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
213 if (err)
214 goto out_unlock;
215 memcpy (de->name, name, namelen);
216 memset (de->name + namelen, 0, SYSV_DIRSIZE - namelen - 2);
217 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
218 err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
219 dir->i_mtime = dir->i_ctime = current_time(dir);
220 mark_inode_dirty(dir);
221out_page:
222 dir_put_page(page);
223out:
224 return err;
225out_unlock:
226 unlock_page(page);
227 goto out_page;
228}
229
230int sysv_delete_entry(struct sysv_dir_entry *de, struct page *page)
231{
232 struct inode *inode = page->mapping->host;
233 char *kaddr = (char*)page_address(page);
234 loff_t pos = page_offset(page) + (char *)de - kaddr;
235 int err;
236
237 lock_page(page);
238 err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
239 BUG_ON(err);
240 de->inode = 0;
241 err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
242 dir_put_page(page);
243 inode->i_ctime = inode->i_mtime = current_time(inode);
244 mark_inode_dirty(inode);
245 return err;
246}
247
248int sysv_make_empty(struct inode *inode, struct inode *dir)
249{
250 struct page *page = grab_cache_page(inode->i_mapping, 0);
251 struct sysv_dir_entry * de;
252 char *base;
253 int err;
254
255 if (!page)
256 return -ENOMEM;
257 err = sysv_prepare_chunk(page, 0, 2 * SYSV_DIRSIZE);
258 if (err) {
259 unlock_page(page);
260 goto fail;
261 }
262 kmap(page);
263
264 base = (char*)page_address(page);
265 memset(base, 0, PAGE_SIZE);
266
267 de = (struct sysv_dir_entry *) base;
268 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
269 strcpy(de->name,".");
270 de++;
271 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), dir->i_ino);
272 strcpy(de->name,"..");
273
274 kunmap(page);
275 err = dir_commit_chunk(page, 0, 2 * SYSV_DIRSIZE);
276fail:
277 put_page(page);
278 return err;
279}
280
281/*
282 * routine to check that the specified directory is empty (for rmdir)
283 */
284int sysv_empty_dir(struct inode * inode)
285{
286 struct super_block *sb = inode->i_sb;
287 struct page *page = NULL;
288 unsigned long i, npages = dir_pages(inode);
289
290 for (i = 0; i < npages; i++) {
291 char *kaddr;
292 struct sysv_dir_entry * de;
293 page = dir_get_page(inode, i);
294
295 if (IS_ERR(page))
296 continue;
297
298 kaddr = (char *)page_address(page);
299 de = (struct sysv_dir_entry *)kaddr;
300 kaddr += PAGE_SIZE-SYSV_DIRSIZE;
301
302 for ( ;(char *)de <= kaddr; de++) {
303 if (!de->inode)
304 continue;
305 /* check for . and .. */
306 if (de->name[0] != '.')
307 goto not_empty;
308 if (!de->name[1]) {
309 if (de->inode == cpu_to_fs16(SYSV_SB(sb),
310 inode->i_ino))
311 continue;
312 goto not_empty;
313 }
314 if (de->name[1] != '.' || de->name[2])
315 goto not_empty;
316 }
317 dir_put_page(page);
318 }
319 return 1;
320
321not_empty:
322 dir_put_page(page);
323 return 0;
324}
325
326/* Releases the page */
327void sysv_set_link(struct sysv_dir_entry *de, struct page *page,
328 struct inode *inode)
329{
330 struct inode *dir = page->mapping->host;
331 loff_t pos = page_offset(page) +
332 (char *)de-(char*)page_address(page);
333 int err;
334
335 lock_page(page);
336 err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
337 BUG_ON(err);
338 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
339 err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
340 dir_put_page(page);
341 dir->i_mtime = dir->i_ctime = current_time(dir);
342 mark_inode_dirty(dir);
343}
344
345struct sysv_dir_entry * sysv_dotdot (struct inode *dir, struct page **p)
346{
347 struct page *page = dir_get_page(dir, 0);
348 struct sysv_dir_entry *de = NULL;
349
350 if (!IS_ERR(page)) {
351 de = (struct sysv_dir_entry*) page_address(page) + 1;
352 *p = page;
353 }
354 return de;
355}
356
357ino_t sysv_inode_by_name(struct dentry *dentry)
358{
359 struct page *page;
360 struct sysv_dir_entry *de = sysv_find_entry (dentry, &page);
361 ino_t res = 0;
362
363 if (de) {
364 res = fs16_to_cpu(SYSV_SB(dentry->d_sb), de->inode);
365 dir_put_page(page);
366 }
367 return res;
368}