aboutsummaryrefslogtreecommitdiffstats
path: root/fs/minix/dir.c
blob: 2b0a389d19874765585f3565102005f6facdc470 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
/*
 *  linux/fs/minix/dir.c
 *
 *  Copyright (C) 1991, 1992 Linus Torvalds
 *
 *  minix directory handling functions
 */

#include "minix.h"
#include <linux/highmem.h>
#include <linux/smp_lock.h>

typedef struct minix_dir_entry minix_dirent;

static int minix_readdir(struct file *, void *, filldir_t);

const struct file_operations minix_dir_operations = {
	.read		= generic_read_dir,
	.readdir	= minix_readdir,
	.fsync		= minix_sync_file,
};

static inline void dir_put_page(struct page *page)
{
	kunmap(page);
	page_cache_release(page);
}

/*
 * Return the offset into page `page_nr' of the last valid
 * byte in that page, plus one.
 */
static unsigned
minix_last_byte(struct inode *inode, unsigned long page_nr)
{
	unsigned last_byte = PAGE_CACHE_SIZE;

	if (page_nr == (inode->i_size >> PAGE_CACHE_SHIFT))
		last_byte = inode->i_size & (PAGE_CACHE_SIZE - 1);
	return last_byte;
}

static inline unsigned long dir_pages(struct inode *inode)
{
	return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
}

static int dir_commit_chunk(struct page *page, unsigned from, unsigned to)
{
	struct inode *dir = (struct inode *)page->mapping->host;
	int err = 0;
	page->mapping->a_ops->commit_write(NULL, page, from, to);
	if (IS_DIRSYNC(dir))
		err = write_one_page(page, 1);
	else
		unlock_page(page);
	return err;
}

static struct page * dir_get_page(struct inode *dir, unsigned long n)
{
	struct address_space *mapping = dir->i_mapping;
	struct page *page = read_mapping_page(mapping, n, NULL);
	if (!IS_ERR(page)) {
		wait_on_page_locked(page);
		kmap(page);
		if (!PageUptodate(page))
			goto fail;
	}
	return page;

fail:
	dir_put_page(page);
	return ERR_PTR(-EIO);
}

static inline void *minix_next_entry(void *de, struct minix_sb_info *sbi)
{
	return (void*)((char*)de + sbi->s_dirsize);
}

static int minix_readdir(struct file * filp, void * dirent, filldir_t filldir)
{
	unsigned long pos = filp->f_pos;
	struct inode *inode = filp->f_dentry->d_inode;
	struct super_block *sb = inode->i_sb;
	unsigned offset = pos & ~PAGE_CACHE_MASK;
	unsigned long n = pos >> PAGE_CACHE_SHIFT;
	unsigned long npages = dir_pages(inode);
	struct minix_sb_info *sbi = minix_sb(sb);
	unsigned chunk_size = sbi->s_dirsize;

	lock_kernel();

	pos = (pos + chunk_size-1) & ~(chunk_size-1);
	if (pos >= inode->i_size)
		goto done;

	for ( ; n < npages; n++, offset = 0) {
		char *p, *kaddr, *limit;
		struct page *page = dir_get_page(inode, n);

		if (IS_ERR(page))
			continue;
		kaddr = (char *)page_address(page);
		p = kaddr+offset;
		limit = kaddr + minix_last_byte(inode, n) - chunk_size;
		for ( ; p <= limit ; p = minix_next_entry(p, sbi)) {
			minix_dirent *de = (minix_dirent *)p;
			if (de->inode) {
				int over;
				unsigned l = strnlen(de->name,sbi->s_namelen);

				offset = p - kaddr;
				over = filldir(dirent, de->name, l,
						(n<<PAGE_CACHE_SHIFT) | offset,
						de->inode, DT_UNKNOWN);
				if (over) {
					dir_put_page(page);
					goto done;
				}
			}
		}
		dir_put_page(page);
	}

done:
	filp->f_pos = (n << PAGE_CACHE_SHIFT) | offset;
	unlock_kernel();
	return 0;
}

static inline int namecompare(int len, int maxlen,
	const char * name, const char * buffer)
{
	if (len < maxlen && buffer[len])
		return 0;
	return !memcmp(name, buffer, len);
}

/*
 *	minix_find_entry()
 *
 * finds an entry in the specified directory with the wanted name. It
 * returns the cache buffer in which the entry was found, and the entry
 * itself (as a parameter - res_dir). It does NOT read the inode of the
 * entry - you'll have to do that yourself if you want to.
 */
minix_dirent *minix_find_entry(struct dentry *dentry, struct page **res_page)
{
	const char * name = dentry->d_name.name;
	int namelen = dentry->d_name.len;
	struct inode * dir = dentry->d_parent->d_inode;
	struct super_block * sb = dir->i_sb;
	struct minix_sb_info * sbi = minix_sb(sb);
	unsigned long n;
	unsigned long npages = dir_pages(dir);
	struct page *page = NULL;
	struct minix_dir_entry *de;

	*res_page = NULL;

	for (n = 0; n < npages; n++) {
		char *kaddr;
		page = dir_get_page(dir, n);
		if (IS_ERR(page))
			continue;

		kaddr = (char*)page_address(page);
		de = (struct minix_dir_entry *) kaddr;
		kaddr += minix_last_byte(dir, n) - sbi->s_dirsize;
		for ( ; (char *) de <= kaddr ; de = minix_next_entry(de,sbi)) {
			if (!de->inode)
				continue;
			if (namecompare(namelen,sbi->s_namelen,name,de->name))
				goto found;
		}
		dir_put_page(page);
	}
	return NULL;

found:
	*res_page = page;
	return de;
}

int minix_add_link(struct dentry *dentry, struct inode *inode)
{
	struct inode *dir = dentry->d_parent->d_inode;
	const char * name = dentry->d_name.name;
	int namelen = dentry->d_name.len;
	struct super_block * sb = dir->i_sb;
	struct minix_sb_info * sbi = minix_sb(sb);
	struct page *page = NULL;
	struct minix_dir_entry * de;
	unsigned long npages = dir_pages(dir);
	unsigned long n;
	char *kaddr;
	unsigned from, to;
	int err;

	/*
	 * We take care of directory expansion in the same loop
	 * This code plays outside i_size, so it locks the page
	 * to protect that region.
	 */
	for (n = 0; n <= npages; n++) {
		char *dir_end;

		page = dir_get_page(dir, n);
		err = PTR_ERR(page);
		if (IS_ERR(page))
			goto out;
		lock_page(page);
		kaddr = (char*)page_address(page);
		dir_end = kaddr + minix_last_byte(dir, n);
		de = (minix_dirent *)kaddr;
		kaddr += PAGE_CACHE_SIZE - sbi->s_dirsize;
		while ((char *)de <= kaddr) {
			if ((char *)de == dir_end) {
				/* We hit i_size */
				de->inode = 0;
				goto got_it;
			}
			if (!de->inode)
				goto got_it;
			err = -EEXIST;
			if (namecompare(namelen,sbi->s_namelen,name,de->name))
				goto out_unlock;
			de = minix_next_entry(de, sbi);
		}
		unlock_page(page);
		dir_put_page(page);
	}
	BUG();
	return -EINVAL;

got_it:
	from = (char*)de - (char*)page_address(page);
	to = from + sbi->s_dirsize;
	err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
	if (err)
		goto out_unlock;
	memcpy (de->name, name, namelen);
	memset (de->name + namelen, 0, sbi->s_dirsize - namelen - 2);
	de->inode = inode->i_ino;
	err = dir_commit_chunk(page, from, to);
	dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
	mark_inode_dirty(dir);
out_put:
	dir_put_page(page);
out:
	return err;
out_unlock:
	unlock_page(page);
	goto out_put;
}

int minix_delete_entry(struct minix_dir_entry *de, struct page *page)
{
	struct address_space *mapping = page->mapping;
	struct inode *inode = (struct inode*)mapping->host;
	char *kaddr = page_address(page);
	unsigned from = (char*)de - kaddr;
	unsigned to = from + minix_sb(inode->i_sb)->s_dirsize;
	int err;

	lock_page(page);
	err = mapping->a_ops->prepare_write(NULL, page, from, to);
	if (err == 0) {
		de->inode = 0;
		err = dir_commit_chunk(page, from, to);
	} else {
		unlock_page(page);
	}
	dir_put_page(page);
	inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
	mark_inode_dirty(inode);
	return err;
}

int minix_make_empty(struct inode *inode, struct inode *dir)
{
	struct address_space *mapping = inode->i_mapping;
	struct page *page = grab_cache_page(mapping, 0);
	struct minix_sb_info * sbi = minix_sb(inode->i_sb);
	struct minix_dir_entry * de;
	char *kaddr;
	int err;

	if (!page)
		return -ENOMEM;
	err = mapping->a_ops->prepare_write(NULL, page, 0, 2 * sbi->s_dirsize);
	if (err) {
		unlock_page(page);
		goto fail;
	}

	kaddr = kmap_atomic(page, KM_USER0);
	memset(kaddr, 0, PAGE_CACHE_SIZE);

	de = (struct minix_dir_entry *)kaddr;
	de->inode = inode->i_ino;
	strcpy(de->name,".");
	de = minix_next_entry(de, sbi);
	de->inode = dir->i_ino;
	strcpy(de->name,"..");
	kunmap_atomic(kaddr, KM_USER0);

	err = dir_commit_chunk(page, 0, 2 * sbi->s_dirsize);
fail:
	page_cache_release(page);
	return err;
}

/*
 * routine to check that the specified directory is empty (for rmdir)
 */
int minix_empty_dir(struct inode * inode)
{
	struct page *page = NULL;
	unsigned long i, npages = dir_pages(inode);
	struct minix_sb_info *sbi = minix_sb(inode->i_sb);

	for (i = 0; i < npages; i++) {
		char *kaddr;
		minix_dirent * de;
		page = dir_get_page(inode, i);

		if (IS_ERR(page))
			continue;

		kaddr = (char *)page_address(page);
		de = (minix_dirent *)kaddr;
		kaddr += minix_last_byte(inode, i) - sbi->s_dirsize;

		while ((char *)de <= kaddr) {
			if (de->inode != 0) {
				/* check for . and .. */
				if (de->name[0] != '.')
					goto not_empty;
				if (!de->name[1]) {
					if (de->inode != inode->i_ino)
						goto not_empty;
				} else if (de->name[1] != '.')
					goto not_empty;
				else if (de->name[2])
					goto not_empty;
			}
			de = minix_next_entry(de, sbi);
		}
		dir_put_page(page);
	}
	return 1;

not_empty:
	dir_put_page(page);
	return 0;
}

/* Releases the page */
void minix_set_link(struct minix_dir_entry *de, struct page *page,
	struct inode *inode)
{
	struct inode *dir = (struct inode*)page->mapping->host;
	struct minix_sb_info *sbi = minix_sb(dir->i_sb);
	unsigned from = (char *)de-(char*)page_address(page);
	unsigned to = from + sbi->s_dirsize;
	int err;

	lock_page(page);
	err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
	if (err == 0) {
		de->inode = inode->i_ino;
		err = dir_commit_chunk(page, from, to);
	} else {
		unlock_page(page);
	}
	dir_put_page(page);
	dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
	mark_inode_dirty(dir);
}

struct minix_dir_entry * minix_dotdot (struct inode *dir, struct page **p)
{
	struct page *page = dir_get_page(dir, 0);
	struct minix_sb_info *sbi = minix_sb(dir->i_sb);
	struct minix_dir_entry *de = NULL;

	if (!IS_ERR(page)) {
		de = minix_next_entry(page_address(page), sbi);
		*p = page;
	}
	return de;
}

ino_t minix_inode_by_name(struct dentry *dentry)
{
	struct page *page;
	struct minix_dir_entry *de = minix_find_entry(dentry, &page);
	ino_t res = 0;

	if (de) {
		res = de->inode;
		dir_put_page(page);
	}
	return res;
}