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 = 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 fail: 80 dir_put_page(page); 81 return ERR_PTR(-EIO); 82 } 83 84 static inline void *minix_next_entry(void *de, struct minix_sb_info *sbi) 85 { 86 return (void*)((char*)de + sbi->s_dirsize); 87 } 88 89 static int minix_readdir(struct file * filp, void * dirent, filldir_t filldir) 90 { 91 unsigned long pos = filp->f_pos; 92 struct inode *inode = filp->f_path.dentry->d_inode; 93 struct super_block *sb = inode->i_sb; 94 unsigned offset = pos & ~PAGE_CACHE_MASK; 95 unsigned long n = pos >> PAGE_CACHE_SHIFT; 96 unsigned long npages = dir_pages(inode); 97 struct minix_sb_info *sbi = minix_sb(sb); 98 unsigned chunk_size = sbi->s_dirsize; 99 char *name; 100 __u32 inumber; 101 102 pos = (pos + chunk_size-1) & ~(chunk_size-1); 103 if (pos >= inode->i_size) 104 goto done; 105 106 for ( ; n < npages; n++, offset = 0) { 107 char *p, *kaddr, *limit; 108 struct page *page = dir_get_page(inode, n); 109 110 if (IS_ERR(page)) 111 continue; 112 kaddr = (char *)page_address(page); 113 p = kaddr+offset; 114 limit = kaddr + minix_last_byte(inode, n) - chunk_size; 115 for ( ; p <= limit; p = minix_next_entry(p, sbi)) { 116 if (sbi->s_version == MINIX_V3) { 117 minix3_dirent *de3 = (minix3_dirent *)p; 118 name = de3->name; 119 inumber = de3->inode; 120 } else { 121 minix_dirent *de = (minix_dirent *)p; 122 name = de->name; 123 inumber = de->inode; 124 } 125 if (inumber) { 126 int over; 127 128 unsigned l = strnlen(name, sbi->s_namelen); 129 offset = p - kaddr; 130 over = filldir(dirent, name, l, 131 (n << PAGE_CACHE_SHIFT) | offset, 132 inumber, DT_UNKNOWN); 133 if (over) { 134 dir_put_page(page); 135 goto done; 136 } 137 } 138 } 139 dir_put_page(page); 140 } 141 142 done: 143 filp->f_pos = (n << PAGE_CACHE_SHIFT) | offset; 144 return 0; 145 } 146 147 static inline int namecompare(int len, int maxlen, 148 const char * name, const char * buffer) 149 { 150 if (len < maxlen && buffer[len]) 151 return 0; 152 return !memcmp(name, buffer, len); 153 } 154 155 /* 156 * minix_find_entry() 157 * 158 * finds an entry in the specified directory with the wanted name. It 159 * returns the cache buffer in which the entry was found, and the entry 160 * itself (as a parameter - res_dir). It does NOT read the inode of the 161 * entry - you'll have to do that yourself if you want to. 162 */ 163 minix_dirent *minix_find_entry(struct dentry *dentry, struct page **res_page) 164 { 165 const char * name = dentry->d_name.name; 166 int namelen = dentry->d_name.len; 167 struct inode * dir = dentry->d_parent->d_inode; 168 struct super_block * sb = dir->i_sb; 169 struct minix_sb_info * sbi = minix_sb(sb); 170 unsigned long n; 171 unsigned long npages = dir_pages(dir); 172 struct page *page = NULL; 173 char *p; 174 175 char *namx; 176 __u32 inumber; 177 *res_page = NULL; 178 179 for (n = 0; n < npages; n++) { 180 char *kaddr, *limit; 181 182 page = dir_get_page(dir, n); 183 if (IS_ERR(page)) 184 continue; 185 186 kaddr = (char*)page_address(page); 187 limit = kaddr + minix_last_byte(dir, n) - sbi->s_dirsize; 188 for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) { 189 if (sbi->s_version == MINIX_V3) { 190 minix3_dirent *de3 = (minix3_dirent *)p; 191 namx = de3->name; 192 inumber = de3->inode; 193 } else { 194 minix_dirent *de = (minix_dirent *)p; 195 namx = de->name; 196 inumber = de->inode; 197 } 198 if (!inumber) 199 continue; 200 if (namecompare(namelen, sbi->s_namelen, name, namx)) 201 goto found; 202 } 203 dir_put_page(page); 204 } 205 return NULL; 206 207 found: 208 *res_page = page; 209 return (minix_dirent *)p; 210 } 211 212 int minix_add_link(struct dentry *dentry, struct inode *inode) 213 { 214 struct inode *dir = dentry->d_parent->d_inode; 215 const char * name = dentry->d_name.name; 216 int namelen = dentry->d_name.len; 217 struct super_block * sb = dir->i_sb; 218 struct minix_sb_info * sbi = minix_sb(sb); 219 struct page *page = NULL; 220 unsigned long npages = dir_pages(dir); 221 unsigned long n; 222 char *kaddr, *p; 223 minix_dirent *de; 224 minix3_dirent *de3; 225 loff_t pos; 226 int err; 227 char *namx = NULL; 228 __u32 inumber; 229 230 /* 231 * We take care of directory expansion in the same loop 232 * This code plays outside i_size, so it locks the page 233 * to protect that region. 234 */ 235 for (n = 0; n <= npages; n++) { 236 char *limit, *dir_end; 237 238 page = dir_get_page(dir, n); 239 err = PTR_ERR(page); 240 if (IS_ERR(page)) 241 goto out; 242 lock_page(page); 243 kaddr = (char*)page_address(page); 244 dir_end = kaddr + minix_last_byte(dir, n); 245 limit = kaddr + PAGE_CACHE_SIZE - sbi->s_dirsize; 246 for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) { 247 de = (minix_dirent *)p; 248 de3 = (minix3_dirent *)p; 249 if (sbi->s_version == MINIX_V3) { 250 namx = de3->name; 251 inumber = de3->inode; 252 } else { 253 namx = de->name; 254 inumber = de->inode; 255 } 256 if (p == dir_end) { 257 /* We hit i_size */ 258 if (sbi->s_version == MINIX_V3) 259 de3->inode = 0; 260 else 261 de->inode = 0; 262 goto got_it; 263 } 264 if (!inumber) 265 goto got_it; 266 err = -EEXIST; 267 if (namecompare(namelen, sbi->s_namelen, name, namx)) 268 goto out_unlock; 269 } 270 unlock_page(page); 271 dir_put_page(page); 272 } 273 BUG(); 274 return -EINVAL; 275 276 got_it: 277 pos = page_offset(page) + p - (char *)page_address(page); 278 err = __minix_write_begin(NULL, page->mapping, pos, sbi->s_dirsize, 279 AOP_FLAG_UNINTERRUPTIBLE, &page, NULL); 280 if (err) 281 goto out_unlock; 282 memcpy (namx, name, namelen); 283 if (sbi->s_version == MINIX_V3) { 284 memset (namx + namelen, 0, sbi->s_dirsize - namelen - 4); 285 de3->inode = inode->i_ino; 286 } else { 287 memset (namx + namelen, 0, sbi->s_dirsize - namelen - 2); 288 de->inode = inode->i_ino; 289 } 290 err = dir_commit_chunk(page, pos, sbi->s_dirsize); 291 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC; 292 mark_inode_dirty(dir); 293 out_put: 294 dir_put_page(page); 295 out: 296 return err; 297 out_unlock: 298 unlock_page(page); 299 goto out_put; 300 } 301 302 int minix_delete_entry(struct minix_dir_entry *de, struct page *page) 303 { 304 struct address_space *mapping = page->mapping; 305 struct inode *inode = (struct inode*)mapping->host; 306 char *kaddr = page_address(page); 307 loff_t pos = page_offset(page) + (char*)de - kaddr; 308 struct minix_sb_info *sbi = minix_sb(inode->i_sb); 309 unsigned len = sbi->s_dirsize; 310 int err; 311 312 lock_page(page); 313 err = __minix_write_begin(NULL, mapping, pos, len, 314 AOP_FLAG_UNINTERRUPTIBLE, &page, NULL); 315 if (err == 0) { 316 if (sbi->s_version == MINIX_V3) 317 ((minix3_dirent *) de)->inode = 0; 318 else 319 de->inode = 0; 320 err = dir_commit_chunk(page, pos, len); 321 } else { 322 unlock_page(page); 323 } 324 dir_put_page(page); 325 inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC; 326 mark_inode_dirty(inode); 327 return err; 328 } 329 330 int minix_make_empty(struct inode *inode, struct inode *dir) 331 { 332 struct address_space *mapping = inode->i_mapping; 333 struct page *page = grab_cache_page(mapping, 0); 334 struct minix_sb_info *sbi = minix_sb(inode->i_sb); 335 char *kaddr; 336 int err; 337 338 if (!page) 339 return -ENOMEM; 340 err = __minix_write_begin(NULL, mapping, 0, 2 * sbi->s_dirsize, 341 AOP_FLAG_UNINTERRUPTIBLE, &page, NULL); 342 if (err) { 343 unlock_page(page); 344 goto fail; 345 } 346 347 kaddr = kmap_atomic(page, KM_USER0); 348 memset(kaddr, 0, PAGE_CACHE_SIZE); 349 350 if (sbi->s_version == MINIX_V3) { 351 minix3_dirent *de3 = (minix3_dirent *)kaddr; 352 353 de3->inode = inode->i_ino; 354 strcpy(de3->name, "."); 355 de3 = minix_next_entry(de3, sbi); 356 de3->inode = dir->i_ino; 357 strcpy(de3->name, ".."); 358 } else { 359 minix_dirent *de = (minix_dirent *)kaddr; 360 361 de->inode = inode->i_ino; 362 strcpy(de->name, "."); 363 de = minix_next_entry(de, sbi); 364 de->inode = dir->i_ino; 365 strcpy(de->name, ".."); 366 } 367 kunmap_atomic(kaddr, KM_USER0); 368 369 err = dir_commit_chunk(page, 0, 2 * sbi->s_dirsize); 370 fail: 371 page_cache_release(page); 372 return err; 373 } 374 375 /* 376 * routine to check that the specified directory is empty (for rmdir) 377 */ 378 int minix_empty_dir(struct inode * inode) 379 { 380 struct page *page = NULL; 381 unsigned long i, npages = dir_pages(inode); 382 struct minix_sb_info *sbi = minix_sb(inode->i_sb); 383 char *name; 384 __u32 inumber; 385 386 for (i = 0; i < npages; i++) { 387 char *p, *kaddr, *limit; 388 389 page = dir_get_page(inode, i); 390 if (IS_ERR(page)) 391 continue; 392 393 kaddr = (char *)page_address(page); 394 limit = kaddr + minix_last_byte(inode, i) - sbi->s_dirsize; 395 for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) { 396 if (sbi->s_version == MINIX_V3) { 397 minix3_dirent *de3 = (minix3_dirent *)p; 398 name = de3->name; 399 inumber = de3->inode; 400 } else { 401 minix_dirent *de = (minix_dirent *)p; 402 name = de->name; 403 inumber = de->inode; 404 } 405 406 if (inumber != 0) { 407 /* check for . and .. */ 408 if (name[0] != '.') 409 goto not_empty; 410 if (!name[1]) { 411 if (inumber != inode->i_ino) 412 goto not_empty; 413 } else if (name[1] != '.') 414 goto not_empty; 415 else if (name[2]) 416 goto not_empty; 417 } 418 } 419 dir_put_page(page); 420 } 421 return 1; 422 423 not_empty: 424 dir_put_page(page); 425 return 0; 426 } 427 428 /* Releases the page */ 429 void minix_set_link(struct minix_dir_entry *de, struct page *page, 430 struct inode *inode) 431 { 432 struct address_space *mapping = page->mapping; 433 struct inode *dir = mapping->host; 434 struct minix_sb_info *sbi = minix_sb(dir->i_sb); 435 loff_t pos = page_offset(page) + 436 (char *)de-(char*)page_address(page); 437 int err; 438 439 lock_page(page); 440 441 err = __minix_write_begin(NULL, mapping, pos, sbi->s_dirsize, 442 AOP_FLAG_UNINTERRUPTIBLE, &page, NULL); 443 if (err == 0) { 444 if (sbi->s_version == MINIX_V3) 445 ((minix3_dirent *) de)->inode = inode->i_ino; 446 else 447 de->inode = inode->i_ino; 448 err = dir_commit_chunk(page, pos, sbi->s_dirsize); 449 } else { 450 unlock_page(page); 451 } 452 dir_put_page(page); 453 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC; 454 mark_inode_dirty(dir); 455 } 456 457 struct minix_dir_entry * minix_dotdot (struct inode *dir, struct page **p) 458 { 459 struct page *page = dir_get_page(dir, 0); 460 struct minix_sb_info *sbi = minix_sb(dir->i_sb); 461 struct minix_dir_entry *de = NULL; 462 463 if (!IS_ERR(page)) { 464 de = minix_next_entry(page_address(page), sbi); 465 *p = page; 466 } 467 return de; 468 } 469 470 ino_t minix_inode_by_name(struct dentry *dentry) 471 { 472 struct page *page; 473 struct minix_dir_entry *de = minix_find_entry(dentry, &page); 474 ino_t res = 0; 475 476 if (de) { 477 struct address_space *mapping = page->mapping; 478 struct inode *inode = mapping->host; 479 struct minix_sb_info *sbi = minix_sb(inode->i_sb); 480 481 if (sbi->s_version == MINIX_V3) 482 res = ((minix3_dirent *) de)->inode; 483 else 484 res = de->inode; 485 dir_put_page(page); 486 } 487 return res; 488 } 489