xref: /openbmc/linux/fs/minix/dir.c (revision fd589a8f) 
1 /*
2  *  linux/fs/minix/dir.c
3  *
4  *  Copyright (C) 1991, 1992 Linus Torvalds
5  *
6  *  minix directory handling functions
7  *
8  *  Updated to filesystem version 3 by Daniel Aragones
9  */
10 
11 #include "minix.h"
12 #include <linux/buffer_head.h>
13 #include <linux/highmem.h>
14 #include <linux/swap.h>
15 
16 typedef struct minix_dir_entry minix_dirent;
17 typedef struct minix3_dir_entry minix3_dirent;
18 
19 static int minix_readdir(struct file *, void *, filldir_t);
20 
21 const struct file_operations minix_dir_operations = {
22 	.llseek		= generic_file_llseek,
23 	.read		= generic_read_dir,
24 	.readdir	= minix_readdir,
25 	.fsync		= simple_fsync,
26 };
27 
28 static inline void dir_put_page(struct page *page)
29 {
30 	kunmap(page);
31 	page_cache_release(page);
32 }
33 
34 /*
35  * Return the offset into page `page_nr' of the last valid
36  * byte in that page, plus one.
37  */
38 static unsigned
39 minix_last_byte(struct inode *inode, unsigned long page_nr)
40 {
41 	unsigned last_byte = PAGE_CACHE_SIZE;
42 
43 	if (page_nr == (inode->i_size >> PAGE_CACHE_SHIFT))
44 		last_byte = inode->i_size & (PAGE_CACHE_SIZE - 1);
45 	return last_byte;
46 }
47 
48 static inline unsigned long dir_pages(struct inode *inode)
49 {
50 	return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
51 }
52 
53 static int dir_commit_chunk(struct page *page, loff_t pos, unsigned len)
54 {
55 	struct address_space *mapping = page->mapping;
56 	struct inode *dir = mapping->host;
57 	int err = 0;
58 	block_write_end(NULL, mapping, pos, len, len, page, NULL);
59 
60 	if (pos+len > dir->i_size) {
61 		i_size_write(dir, pos+len);
62 		mark_inode_dirty(dir);
63 	}
64 	if (IS_DIRSYNC(dir))
65 		err = write_one_page(page, 1);
66 	else
67 		unlock_page(page);
68 	return err;
69 }
70 
71 static struct page * dir_get_page(struct inode *dir, unsigned long n)
72 {
73 	struct address_space *mapping = dir->i_mapping;
74 	struct page *page = read_mapping_page(mapping, n, NULL);
75 	if (!IS_ERR(page)) {
76 		kmap(page);
77 		if (!PageUptodate(page))
78 			goto fail;
79 	}
80 	return page;
81 
82 fail:
83 	dir_put_page(page);
84 	return ERR_PTR(-EIO);
85 }
86 
87 static inline void *minix_next_entry(void *de, struct minix_sb_info *sbi)
88 {
89 	return (void*)((char*)de + sbi->s_dirsize);
90 }
91 
92 static int minix_readdir(struct file * filp, void * dirent, filldir_t filldir)
93 {
94 	unsigned long pos = filp->f_pos;
95 	struct inode *inode = filp->f_path.dentry->d_inode;
96 	struct super_block *sb = inode->i_sb;
97 	unsigned offset = pos & ~PAGE_CACHE_MASK;
98 	unsigned long n = pos >> PAGE_CACHE_SHIFT;
99 	unsigned long npages = dir_pages(inode);
100 	struct minix_sb_info *sbi = minix_sb(sb);
101 	unsigned chunk_size = sbi->s_dirsize;
102 	char *name;
103 	__u32 inumber;
104 
105 	pos = (pos + chunk_size-1) & ~(chunk_size-1);
106 	if (pos >= inode->i_size)
107 		goto done;
108 
109 	for ( ; n < npages; n++, offset = 0) {
110 		char *p, *kaddr, *limit;
111 		struct page *page = dir_get_page(inode, n);
112 
113 		if (IS_ERR(page))
114 			continue;
115 		kaddr = (char *)page_address(page);
116 		p = kaddr+offset;
117 		limit = kaddr + minix_last_byte(inode, n) - chunk_size;
118 		for ( ; p <= limit; p = minix_next_entry(p, sbi)) {
119 			if (sbi->s_version == MINIX_V3) {
120 				minix3_dirent *de3 = (minix3_dirent *)p;
121 				name = de3->name;
122 				inumber = de3->inode;
123 	 		} else {
124 				minix_dirent *de = (minix_dirent *)p;
125 				name = de->name;
126 				inumber = de->inode;
127 			}
128 			if (inumber) {
129 				int over;
130 
131 				unsigned l = strnlen(name, sbi->s_namelen);
132 				offset = p - kaddr;
133 				over = filldir(dirent, name, l,
134 					(n << PAGE_CACHE_SHIFT) | offset,
135 					inumber, DT_UNKNOWN);
136 				if (over) {
137 					dir_put_page(page);
138 					goto done;
139 				}
140 			}
141 		}
142 		dir_put_page(page);
143 	}
144 
145 done:
146 	filp->f_pos = (n << PAGE_CACHE_SHIFT) | offset;
147 	return 0;
148 }
149 
150 static inline int namecompare(int len, int maxlen,
151 	const char * name, const char * buffer)
152 {
153 	if (len < maxlen && buffer[len])
154 		return 0;
155 	return !memcmp(name, buffer, len);
156 }
157 
158 /*
159  *	minix_find_entry()
160  *
161  * finds an entry in the specified directory with the wanted name. It
162  * returns the cache buffer in which the entry was found, and the entry
163  * itself (as a parameter - res_dir). It does NOT read the inode of the
164  * entry - you'll have to do that yourself if you want to.
165  */
166 minix_dirent *minix_find_entry(struct dentry *dentry, struct page **res_page)
167 {
168 	const char * name = dentry->d_name.name;
169 	int namelen = dentry->d_name.len;
170 	struct inode * dir = dentry->d_parent->d_inode;
171 	struct super_block * sb = dir->i_sb;
172 	struct minix_sb_info * sbi = minix_sb(sb);
173 	unsigned long n;
174 	unsigned long npages = dir_pages(dir);
175 	struct page *page = NULL;
176 	char *p;
177 
178 	char *namx;
179 	__u32 inumber;
180 	*res_page = NULL;
181 
182 	for (n = 0; n < npages; n++) {
183 		char *kaddr, *limit;
184 
185 		page = dir_get_page(dir, n);
186 		if (IS_ERR(page))
187 			continue;
188 
189 		kaddr = (char*)page_address(page);
190 		limit = kaddr + minix_last_byte(dir, n) - sbi->s_dirsize;
191 		for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) {
192 			if (sbi->s_version == MINIX_V3) {
193 				minix3_dirent *de3 = (minix3_dirent *)p;
194 				namx = de3->name;
195 				inumber = de3->inode;
196  			} else {
197 				minix_dirent *de = (minix_dirent *)p;
198 				namx = de->name;
199 				inumber = de->inode;
200 			}
201 			if (!inumber)
202 				continue;
203 			if (namecompare(namelen, sbi->s_namelen, name, namx))
204 				goto found;
205 		}
206 		dir_put_page(page);
207 	}
208 	return NULL;
209 
210 found:
211 	*res_page = page;
212 	return (minix_dirent *)p;
213 }
214 
215 int minix_add_link(struct dentry *dentry, struct inode *inode)
216 {
217 	struct inode *dir = dentry->d_parent->d_inode;
218 	const char * name = dentry->d_name.name;
219 	int namelen = dentry->d_name.len;
220 	struct super_block * sb = dir->i_sb;
221 	struct minix_sb_info * sbi = minix_sb(sb);
222 	struct page *page = NULL;
223 	unsigned long npages = dir_pages(dir);
224 	unsigned long n;
225 	char *kaddr, *p;
226 	minix_dirent *de;
227 	minix3_dirent *de3;
228 	loff_t pos;
229 	int err;
230 	char *namx = NULL;
231 	__u32 inumber;
232 
233 	/*
234 	 * We take care of directory expansion in the same loop
235 	 * This code plays outside i_size, so it locks the page
236 	 * to protect that region.
237 	 */
238 	for (n = 0; n <= npages; n++) {
239 		char *limit, *dir_end;
240 
241 		page = dir_get_page(dir, n);
242 		err = PTR_ERR(page);
243 		if (IS_ERR(page))
244 			goto out;
245 		lock_page(page);
246 		kaddr = (char*)page_address(page);
247 		dir_end = kaddr + minix_last_byte(dir, n);
248 		limit = kaddr + PAGE_CACHE_SIZE - sbi->s_dirsize;
249 		for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) {
250 			de = (minix_dirent *)p;
251 			de3 = (minix3_dirent *)p;
252 			if (sbi->s_version == MINIX_V3) {
253 				namx = de3->name;
254 				inumber = de3->inode;
255 		 	} else {
256   				namx = de->name;
257 				inumber = de->inode;
258 			}
259 			if (p == dir_end) {
260 				/* We hit i_size */
261 				if (sbi->s_version == MINIX_V3)
262 					de3->inode = 0;
263 		 		else
264 					de->inode = 0;
265 				goto got_it;
266 			}
267 			if (!inumber)
268 				goto got_it;
269 			err = -EEXIST;
270 			if (namecompare(namelen, sbi->s_namelen, name, namx))
271 				goto out_unlock;
272 		}
273 		unlock_page(page);
274 		dir_put_page(page);
275 	}
276 	BUG();
277 	return -EINVAL;
278 
279 got_it:
280 	pos = page_offset(page) + p - (char *)page_address(page);
281 	err = __minix_write_begin(NULL, page->mapping, pos, sbi->s_dirsize,
282 					AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
283 	if (err)
284 		goto out_unlock;
285 	memcpy (namx, name, namelen);
286 	if (sbi->s_version == MINIX_V3) {
287 		memset (namx + namelen, 0, sbi->s_dirsize - namelen - 4);
288 		de3->inode = inode->i_ino;
289 	} else {
290 		memset (namx + namelen, 0, sbi->s_dirsize - namelen - 2);
291 		de->inode = inode->i_ino;
292 	}
293 	err = dir_commit_chunk(page, pos, sbi->s_dirsize);
294 	dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
295 	mark_inode_dirty(dir);
296 out_put:
297 	dir_put_page(page);
298 out:
299 	return err;
300 out_unlock:
301 	unlock_page(page);
302 	goto out_put;
303 }
304 
305 int minix_delete_entry(struct minix_dir_entry *de, struct page *page)
306 {
307 	struct address_space *mapping = page->mapping;
308 	struct inode *inode = (struct inode*)mapping->host;
309 	char *kaddr = page_address(page);
310 	loff_t pos = page_offset(page) + (char*)de - kaddr;
311 	unsigned len = minix_sb(inode->i_sb)->s_dirsize;
312 	int err;
313 
314 	lock_page(page);
315 	err = __minix_write_begin(NULL, mapping, pos, len,
316 					AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
317 	if (err == 0) {
318 		de->inode = 0;
319 		err = dir_commit_chunk(page, pos, len);
320 	} else {
321 		unlock_page(page);
322 	}
323 	dir_put_page(page);
324 	inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
325 	mark_inode_dirty(inode);
326 	return err;
327 }
328 
329 int minix_make_empty(struct inode *inode, struct inode *dir)
330 {
331 	struct address_space *mapping = inode->i_mapping;
332 	struct page *page = grab_cache_page(mapping, 0);
333 	struct minix_sb_info *sbi = minix_sb(inode->i_sb);
334 	char *kaddr;
335 	int err;
336 
337 	if (!page)
338 		return -ENOMEM;
339 	err = __minix_write_begin(NULL, mapping, 0, 2 * sbi->s_dirsize,
340 					AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
341 	if (err) {
342 		unlock_page(page);
343 		goto fail;
344 	}
345 
346 	kaddr = kmap_atomic(page, KM_USER0);
347 	memset(kaddr, 0, PAGE_CACHE_SIZE);
348 
349 	if (sbi->s_version == MINIX_V3) {
350 		minix3_dirent *de3 = (minix3_dirent *)kaddr;
351 
352 		de3->inode = inode->i_ino;
353 		strcpy(de3->name, ".");
354 		de3 = minix_next_entry(de3, sbi);
355 		de3->inode = dir->i_ino;
356 		strcpy(de3->name, "..");
357 	} else {
358 		minix_dirent *de = (minix_dirent *)kaddr;
359 
360 		de->inode = inode->i_ino;
361 		strcpy(de->name, ".");
362 		de = minix_next_entry(de, sbi);
363 		de->inode = dir->i_ino;
364 		strcpy(de->name, "..");
365 	}
366 	kunmap_atomic(kaddr, KM_USER0);
367 
368 	err = dir_commit_chunk(page, 0, 2 * sbi->s_dirsize);
369 fail:
370 	page_cache_release(page);
371 	return err;
372 }
373 
374 /*
375  * routine to check that the specified directory is empty (for rmdir)
376  */
377 int minix_empty_dir(struct inode * inode)
378 {
379 	struct page *page = NULL;
380 	unsigned long i, npages = dir_pages(inode);
381 	struct minix_sb_info *sbi = minix_sb(inode->i_sb);
382 	char *name;
383 	__u32 inumber;
384 
385 	for (i = 0; i < npages; i++) {
386 		char *p, *kaddr, *limit;
387 
388 		page = dir_get_page(inode, i);
389 		if (IS_ERR(page))
390 			continue;
391 
392 		kaddr = (char *)page_address(page);
393 		limit = kaddr + minix_last_byte(inode, i) - sbi->s_dirsize;
394 		for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) {
395 			if (sbi->s_version == MINIX_V3) {
396 				minix3_dirent *de3 = (minix3_dirent *)p;
397 				name = de3->name;
398 				inumber = de3->inode;
399 			} else {
400 				minix_dirent *de = (minix_dirent *)p;
401 				name = de->name;
402 				inumber = de->inode;
403 			}
404 
405 			if (inumber != 0) {
406 				/* check for . and .. */
407 				if (name[0] != '.')
408 					goto not_empty;
409 				if (!name[1]) {
410 					if (inumber != inode->i_ino)
411 						goto not_empty;
412 				} else if (name[1] != '.')
413 					goto not_empty;
414 				else if (name[2])
415 					goto not_empty;
416 			}
417 		}
418 		dir_put_page(page);
419 	}
420 	return 1;
421 
422 not_empty:
423 	dir_put_page(page);
424 	return 0;
425 }
426 
427 /* Releases the page */
428 void minix_set_link(struct minix_dir_entry *de, struct page *page,
429 	struct inode *inode)
430 {
431 	struct address_space *mapping = page->mapping;
432 	struct inode *dir = mapping->host;
433 	struct minix_sb_info *sbi = minix_sb(dir->i_sb);
434 	loff_t pos = page_offset(page) +
435 			(char *)de-(char*)page_address(page);
436 	int err;
437 
438 	lock_page(page);
439 
440 	err = __minix_write_begin(NULL, mapping, pos, sbi->s_dirsize,
441 					AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
442 	if (err == 0) {
443 		de->inode = inode->i_ino;
444 		err = dir_commit_chunk(page, pos, sbi->s_dirsize);
445 	} else {
446 		unlock_page(page);
447 	}
448 	dir_put_page(page);
449 	dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
450 	mark_inode_dirty(dir);
451 }
452 
453 struct minix_dir_entry * minix_dotdot (struct inode *dir, struct page **p)
454 {
455 	struct page *page = dir_get_page(dir, 0);
456 	struct minix_sb_info *sbi = minix_sb(dir->i_sb);
457 	struct minix_dir_entry *de = NULL;
458 
459 	if (!IS_ERR(page)) {
460 		de = minix_next_entry(page_address(page), sbi);
461 		*p = page;
462 	}
463 	return de;
464 }
465 
466 ino_t minix_inode_by_name(struct dentry *dentry)
467 {
468 	struct page *page;
469 	struct minix_dir_entry *de = minix_find_entry(dentry, &page);
470 	ino_t res = 0;
471 
472 	if (de) {
473 		res = de->inode;
474 		dir_put_page(page);
475 	}
476 	return res;
477 }
478