4 * Copyright (C) 1991, 1992 Linus Torvalds
6 * minix directory handling functions
8 * Updated to filesystem version 3 by Daniel Aragones
12 #include <linux/buffer_head.h>
13 #include <linux/highmem.h>
14 #include <linux/swap.h>
16 typedef struct minix_dir_entry minix_dirent;
17 typedef struct minix3_dir_entry minix3_dirent;
19 static int minix_readdir(struct file *, struct dir_context *);
21 const struct file_operations minix_dir_operations = {
22 .llseek = generic_file_llseek,
23 .read = generic_read_dir,
24 .iterate = minix_readdir,
25 .fsync = generic_file_fsync,
28 static inline void dir_put_page(struct page *page)
31 page_cache_release(page);
35 * Return the offset into page `page_nr' of the last valid
36 * byte in that page, plus one.
39 minix_last_byte(struct inode *inode, unsigned long page_nr)
41 unsigned last_byte = PAGE_CACHE_SIZE;
43 if (page_nr == (inode->i_size >> PAGE_CACHE_SHIFT))
44 last_byte = inode->i_size & (PAGE_CACHE_SIZE - 1);
48 static inline unsigned long dir_pages(struct inode *inode)
50 return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
53 static int dir_commit_chunk(struct page *page, loff_t pos, unsigned len)
55 struct address_space *mapping = page->mapping;
56 struct inode *dir = mapping->host;
58 block_write_end(NULL, mapping, pos, len, len, page, NULL);
60 if (pos+len > dir->i_size) {
61 i_size_write(dir, pos+len);
62 mark_inode_dirty(dir);
65 err = write_one_page(page, 1);
71 static struct page * dir_get_page(struct inode *dir, unsigned long n)
73 struct address_space *mapping = dir->i_mapping;
74 struct page *page = read_mapping_page(mapping, n, NULL);
80 static inline void *minix_next_entry(void *de, struct minix_sb_info *sbi)
82 return (void*)((char*)de + sbi->s_dirsize);
85 static int minix_readdir(struct file *file, struct dir_context *ctx)
87 struct inode *inode = file_inode(file);
88 struct super_block *sb = inode->i_sb;
89 struct minix_sb_info *sbi = minix_sb(sb);
90 unsigned chunk_size = sbi->s_dirsize;
91 unsigned long npages = dir_pages(inode);
92 unsigned long pos = ctx->pos;
96 ctx->pos = pos = ALIGN(pos, chunk_size);
97 if (pos >= inode->i_size)
100 offset = pos & ~PAGE_CACHE_MASK;
101 n = pos >> PAGE_CACHE_SHIFT;
103 for ( ; n < npages; n++, offset = 0) {
104 char *p, *kaddr, *limit;
105 struct page *page = dir_get_page(inode, n);
109 kaddr = (char *)page_address(page);
111 limit = kaddr + minix_last_byte(inode, n) - chunk_size;
112 for ( ; p <= limit; p = minix_next_entry(p, sbi)) {
115 if (sbi->s_version == MINIX_V3) {
116 minix3_dirent *de3 = (minix3_dirent *)p;
118 inumber = de3->inode;
120 minix_dirent *de = (minix_dirent *)p;
125 unsigned l = strnlen(name, sbi->s_namelen);
126 if (!dir_emit(ctx, name, l,
127 inumber, DT_UNKNOWN)) {
132 ctx->pos += chunk_size;
139 static inline int namecompare(int len, int maxlen,
140 const char * name, const char * buffer)
142 if (len < maxlen && buffer[len])
144 return !memcmp(name, buffer, len);
150 * finds an entry in the specified directory with the wanted name. It
151 * returns the cache buffer in which the entry was found, and the entry
152 * itself (as a parameter - res_dir). It does NOT read the inode of the
153 * entry - you'll have to do that yourself if you want to.
155 minix_dirent *minix_find_entry(struct dentry *dentry, struct page **res_page)
157 const char * name = dentry->d_name.name;
158 int namelen = dentry->d_name.len;
159 struct inode * dir = dentry->d_parent->d_inode;
160 struct super_block * sb = dir->i_sb;
161 struct minix_sb_info * sbi = minix_sb(sb);
163 unsigned long npages = dir_pages(dir);
164 struct page *page = NULL;
171 for (n = 0; n < npages; n++) {
174 page = dir_get_page(dir, n);
178 kaddr = (char*)page_address(page);
179 limit = kaddr + minix_last_byte(dir, n) - sbi->s_dirsize;
180 for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) {
181 if (sbi->s_version == MINIX_V3) {
182 minix3_dirent *de3 = (minix3_dirent *)p;
184 inumber = de3->inode;
186 minix_dirent *de = (minix_dirent *)p;
192 if (namecompare(namelen, sbi->s_namelen, name, namx))
201 return (minix_dirent *)p;
204 int minix_add_link(struct dentry *dentry, struct inode *inode)
206 struct inode *dir = dentry->d_parent->d_inode;
207 const char * name = dentry->d_name.name;
208 int namelen = dentry->d_name.len;
209 struct super_block * sb = dir->i_sb;
210 struct minix_sb_info * sbi = minix_sb(sb);
211 struct page *page = NULL;
212 unsigned long npages = dir_pages(dir);
223 * We take care of directory expansion in the same loop
224 * This code plays outside i_size, so it locks the page
225 * to protect that region.
227 for (n = 0; n <= npages; n++) {
228 char *limit, *dir_end;
230 page = dir_get_page(dir, n);
235 kaddr = (char*)page_address(page);
236 dir_end = kaddr + minix_last_byte(dir, n);
237 limit = kaddr + PAGE_CACHE_SIZE - sbi->s_dirsize;
238 for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) {
239 de = (minix_dirent *)p;
240 de3 = (minix3_dirent *)p;
241 if (sbi->s_version == MINIX_V3) {
243 inumber = de3->inode;
250 if (sbi->s_version == MINIX_V3)
259 if (namecompare(namelen, sbi->s_namelen, name, namx))
269 pos = page_offset(page) + p - (char *)page_address(page);
270 err = minix_prepare_chunk(page, pos, sbi->s_dirsize);
273 memcpy (namx, name, namelen);
274 if (sbi->s_version == MINIX_V3) {
275 memset (namx + namelen, 0, sbi->s_dirsize - namelen - 4);
276 de3->inode = inode->i_ino;
278 memset (namx + namelen, 0, sbi->s_dirsize - namelen - 2);
279 de->inode = inode->i_ino;
281 err = dir_commit_chunk(page, pos, sbi->s_dirsize);
282 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
283 mark_inode_dirty(dir);
293 int minix_delete_entry(struct minix_dir_entry *de, struct page *page)
295 struct inode *inode = page->mapping->host;
296 char *kaddr = page_address(page);
297 loff_t pos = page_offset(page) + (char*)de - kaddr;
298 struct minix_sb_info *sbi = minix_sb(inode->i_sb);
299 unsigned len = sbi->s_dirsize;
303 err = minix_prepare_chunk(page, pos, len);
305 if (sbi->s_version == MINIX_V3)
306 ((minix3_dirent *) de)->inode = 0;
309 err = dir_commit_chunk(page, pos, len);
314 inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
315 mark_inode_dirty(inode);
319 int minix_make_empty(struct inode *inode, struct inode *dir)
321 struct page *page = grab_cache_page(inode->i_mapping, 0);
322 struct minix_sb_info *sbi = minix_sb(inode->i_sb);
328 err = minix_prepare_chunk(page, 0, 2 * sbi->s_dirsize);
334 kaddr = kmap_atomic(page);
335 memset(kaddr, 0, PAGE_CACHE_SIZE);
337 if (sbi->s_version == MINIX_V3) {
338 minix3_dirent *de3 = (minix3_dirent *)kaddr;
340 de3->inode = inode->i_ino;
341 strcpy(de3->name, ".");
342 de3 = minix_next_entry(de3, sbi);
343 de3->inode = dir->i_ino;
344 strcpy(de3->name, "..");
346 minix_dirent *de = (minix_dirent *)kaddr;
348 de->inode = inode->i_ino;
349 strcpy(de->name, ".");
350 de = minix_next_entry(de, sbi);
351 de->inode = dir->i_ino;
352 strcpy(de->name, "..");
354 kunmap_atomic(kaddr);
356 err = dir_commit_chunk(page, 0, 2 * sbi->s_dirsize);
358 page_cache_release(page);
363 * routine to check that the specified directory is empty (for rmdir)
365 int minix_empty_dir(struct inode * inode)
367 struct page *page = NULL;
368 unsigned long i, npages = dir_pages(inode);
369 struct minix_sb_info *sbi = minix_sb(inode->i_sb);
373 for (i = 0; i < npages; i++) {
374 char *p, *kaddr, *limit;
376 page = dir_get_page(inode, i);
380 kaddr = (char *)page_address(page);
381 limit = kaddr + minix_last_byte(inode, i) - sbi->s_dirsize;
382 for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) {
383 if (sbi->s_version == MINIX_V3) {
384 minix3_dirent *de3 = (minix3_dirent *)p;
386 inumber = de3->inode;
388 minix_dirent *de = (minix_dirent *)p;
394 /* check for . and .. */
398 if (inumber != inode->i_ino)
400 } else if (name[1] != '.')
415 /* Releases the page */
416 void minix_set_link(struct minix_dir_entry *de, struct page *page,
419 struct inode *dir = page->mapping->host;
420 struct minix_sb_info *sbi = minix_sb(dir->i_sb);
421 loff_t pos = page_offset(page) +
422 (char *)de-(char*)page_address(page);
427 err = minix_prepare_chunk(page, pos, sbi->s_dirsize);
429 if (sbi->s_version == MINIX_V3)
430 ((minix3_dirent *) de)->inode = inode->i_ino;
432 de->inode = inode->i_ino;
433 err = dir_commit_chunk(page, pos, sbi->s_dirsize);
438 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
439 mark_inode_dirty(dir);
442 struct minix_dir_entry * minix_dotdot (struct inode *dir, struct page **p)
444 struct page *page = dir_get_page(dir, 0);
445 struct minix_sb_info *sbi = minix_sb(dir->i_sb);
446 struct minix_dir_entry *de = NULL;
449 de = minix_next_entry(page_address(page), sbi);
455 ino_t minix_inode_by_name(struct dentry *dentry)
458 struct minix_dir_entry *de = minix_find_entry(dentry, &page);
462 struct address_space *mapping = page->mapping;
463 struct inode *inode = mapping->host;
464 struct minix_sb_info *sbi = minix_sb(inode->i_sb);
466 if (sbi->s_version == MINIX_V3)
467 res = ((minix3_dirent *) de)->inode;