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 *, struct dir_context *); 20 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, 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 return page; 78 } 79 80 static inline void *minix_next_entry(void *de, struct minix_sb_info *sbi) 81 { 82 return (void*)((char*)de + sbi->s_dirsize); 83 } 84 85 static int minix_readdir(struct file *file, struct dir_context *ctx) 86 { 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; 93 unsigned offset; 94 unsigned long n; 95 96 ctx->pos = pos = ALIGN(pos, chunk_size); 97 if (pos >= inode->i_size) 98 return 0; 99 100 offset = pos & ~PAGE_CACHE_MASK; 101 n = pos >> PAGE_CACHE_SHIFT; 102 103 for ( ; n < npages; n++, offset = 0) { 104 char *p, *kaddr, *limit; 105 struct page *page = dir_get_page(inode, n); 106 107 if (IS_ERR(page)) 108 continue; 109 kaddr = (char *)page_address(page); 110 p = kaddr+offset; 111 limit = kaddr + minix_last_byte(inode, n) - chunk_size; 112 for ( ; p <= limit; p = minix_next_entry(p, sbi)) { 113 const char *name; 114 __u32 inumber; 115 if (sbi->s_version == MINIX_V3) { 116 minix3_dirent *de3 = (minix3_dirent *)p; 117 name = de3->name; 118 inumber = de3->inode; 119 } else { 120 minix_dirent *de = (minix_dirent *)p; 121 name = de->name; 122 inumber = de->inode; 123 } 124 if (inumber) { 125 unsigned l = strnlen(name, sbi->s_namelen); 126 if (!dir_emit(ctx, name, l, 127 inumber, DT_UNKNOWN)) { 128 dir_put_page(page); 129 return 0; 130 } 131 } 132 ctx->pos += chunk_size; 133 } 134 dir_put_page(page); 135 } 136 return 0; 137 } 138 139 static inline int namecompare(int len, int maxlen, 140 const char * name, const char * buffer) 141 { 142 if (len < maxlen && buffer[len]) 143 return 0; 144 return !memcmp(name, buffer, len); 145 } 146 147 /* 148 * minix_find_entry() 149 * 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. 154 */ 155 minix_dirent *minix_find_entry(struct dentry *dentry, struct page **res_page) 156 { 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); 162 unsigned long n; 163 unsigned long npages = dir_pages(dir); 164 struct page *page = NULL; 165 char *p; 166 167 char *namx; 168 __u32 inumber; 169 *res_page = NULL; 170 171 for (n = 0; n < npages; n++) { 172 char *kaddr, *limit; 173 174 page = dir_get_page(dir, n); 175 if (IS_ERR(page)) 176 continue; 177 178 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; 183 namx = de3->name; 184 inumber = de3->inode; 185 } else { 186 minix_dirent *de = (minix_dirent *)p; 187 namx = de->name; 188 inumber = de->inode; 189 } 190 if (!inumber) 191 continue; 192 if (namecompare(namelen, sbi->s_namelen, name, namx)) 193 goto found; 194 } 195 dir_put_page(page); 196 } 197 return NULL; 198 199 found: 200 *res_page = page; 201 return (minix_dirent *)p; 202 } 203 204 int minix_add_link(struct dentry *dentry, struct inode *inode) 205 { 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); 213 unsigned long n; 214 char *kaddr, *p; 215 minix_dirent *de; 216 minix3_dirent *de3; 217 loff_t pos; 218 int err; 219 char *namx = NULL; 220 __u32 inumber; 221 222 /* 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. 226 */ 227 for (n = 0; n <= npages; n++) { 228 char *limit, *dir_end; 229 230 page = dir_get_page(dir, n); 231 err = PTR_ERR(page); 232 if (IS_ERR(page)) 233 goto out; 234 lock_page(page); 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) { 242 namx = de3->name; 243 inumber = de3->inode; 244 } else { 245 namx = de->name; 246 inumber = de->inode; 247 } 248 if (p == dir_end) { 249 /* We hit i_size */ 250 if (sbi->s_version == MINIX_V3) 251 de3->inode = 0; 252 else 253 de->inode = 0; 254 goto got_it; 255 } 256 if (!inumber) 257 goto got_it; 258 err = -EEXIST; 259 if (namecompare(namelen, sbi->s_namelen, name, namx)) 260 goto out_unlock; 261 } 262 unlock_page(page); 263 dir_put_page(page); 264 } 265 BUG(); 266 return -EINVAL; 267 268 got_it: 269 pos = page_offset(page) + p - (char *)page_address(page); 270 err = minix_prepare_chunk(page, pos, sbi->s_dirsize); 271 if (err) 272 goto out_unlock; 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; 277 } else { 278 memset (namx + namelen, 0, sbi->s_dirsize - namelen - 2); 279 de->inode = inode->i_ino; 280 } 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); 284 out_put: 285 dir_put_page(page); 286 out: 287 return err; 288 out_unlock: 289 unlock_page(page); 290 goto out_put; 291 } 292 293 int minix_delete_entry(struct minix_dir_entry *de, struct page *page) 294 { 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; 300 int err; 301 302 lock_page(page); 303 err = minix_prepare_chunk(page, pos, len); 304 if (err == 0) { 305 if (sbi->s_version == MINIX_V3) 306 ((minix3_dirent *) de)->inode = 0; 307 else 308 de->inode = 0; 309 err = dir_commit_chunk(page, pos, len); 310 } else { 311 unlock_page(page); 312 } 313 dir_put_page(page); 314 inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC; 315 mark_inode_dirty(inode); 316 return err; 317 } 318 319 int minix_make_empty(struct inode *inode, struct inode *dir) 320 { 321 struct page *page = grab_cache_page(inode->i_mapping, 0); 322 struct minix_sb_info *sbi = minix_sb(inode->i_sb); 323 char *kaddr; 324 int err; 325 326 if (!page) 327 return -ENOMEM; 328 err = minix_prepare_chunk(page, 0, 2 * sbi->s_dirsize); 329 if (err) { 330 unlock_page(page); 331 goto fail; 332 } 333 334 kaddr = kmap_atomic(page); 335 memset(kaddr, 0, PAGE_CACHE_SIZE); 336 337 if (sbi->s_version == MINIX_V3) { 338 minix3_dirent *de3 = (minix3_dirent *)kaddr; 339 340 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, ".."); 345 } else { 346 minix_dirent *de = (minix_dirent *)kaddr; 347 348 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, ".."); 353 } 354 kunmap_atomic(kaddr); 355 356 err = dir_commit_chunk(page, 0, 2 * sbi->s_dirsize); 357 fail: 358 page_cache_release(page); 359 return err; 360 } 361 362 /* 363 * routine to check that the specified directory is empty (for rmdir) 364 */ 365 int minix_empty_dir(struct inode * inode) 366 { 367 struct page *page = NULL; 368 unsigned long i, npages = dir_pages(inode); 369 struct minix_sb_info *sbi = minix_sb(inode->i_sb); 370 char *name; 371 __u32 inumber; 372 373 for (i = 0; i < npages; i++) { 374 char *p, *kaddr, *limit; 375 376 page = dir_get_page(inode, i); 377 if (IS_ERR(page)) 378 continue; 379 380 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; 385 name = de3->name; 386 inumber = de3->inode; 387 } else { 388 minix_dirent *de = (minix_dirent *)p; 389 name = de->name; 390 inumber = de->inode; 391 } 392 393 if (inumber != 0) { 394 /* check for . and .. */ 395 if (name[0] != '.') 396 goto not_empty; 397 if (!name[1]) { 398 if (inumber != inode->i_ino) 399 goto not_empty; 400 } else if (name[1] != '.') 401 goto not_empty; 402 else if (name[2]) 403 goto not_empty; 404 } 405 } 406 dir_put_page(page); 407 } 408 return 1; 409 410 not_empty: 411 dir_put_page(page); 412 return 0; 413 } 414 415 /* Releases the page */ 416 void minix_set_link(struct minix_dir_entry *de, struct page *page, 417 struct inode *inode) 418 { 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); 423 int err; 424 425 lock_page(page); 426 427 err = minix_prepare_chunk(page, pos, sbi->s_dirsize); 428 if (err == 0) { 429 if (sbi->s_version == MINIX_V3) 430 ((minix3_dirent *) de)->inode = inode->i_ino; 431 else 432 de->inode = inode->i_ino; 433 err = dir_commit_chunk(page, pos, sbi->s_dirsize); 434 } else { 435 unlock_page(page); 436 } 437 dir_put_page(page); 438 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC; 439 mark_inode_dirty(dir); 440 } 441 442 struct minix_dir_entry * minix_dotdot (struct inode *dir, struct page **p) 443 { 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; 447 448 if (!IS_ERR(page)) { 449 de = minix_next_entry(page_address(page), sbi); 450 *p = page; 451 } 452 return de; 453 } 454 455 ino_t minix_inode_by_name(struct dentry *dentry) 456 { 457 struct page *page; 458 struct minix_dir_entry *de = minix_find_entry(dentry, &page); 459 ino_t res = 0; 460 461 if (de) { 462 struct address_space *mapping = page->mapping; 463 struct inode *inode = mapping->host; 464 struct minix_sb_info *sbi = minix_sb(inode->i_sb); 465 466 if (sbi->s_version == MINIX_V3) 467 res = ((minix3_dirent *) de)->inode; 468 else 469 res = de->inode; 470 dir_put_page(page); 471 } 472 return res; 473 } 474