1 /* 2 * OMFS (as used by RIO Karma) directory operations. 3 * Copyright (C) 2005 Bob Copeland <me@bobcopeland.com> 4 * Released under GPL v2. 5 */ 6 7 #include <linux/fs.h> 8 #include <linux/ctype.h> 9 #include <linux/buffer_head.h> 10 #include "omfs.h" 11 12 static int omfs_hash(const char *name, int namelen, int mod) 13 { 14 int i, hash = 0; 15 for (i = 0; i < namelen; i++) 16 hash ^= tolower(name[i]) << (i % 24); 17 return hash % mod; 18 } 19 20 /* 21 * Finds the bucket for a given name and reads the containing block; 22 * *ofs is set to the offset of the first list entry. 23 */ 24 static struct buffer_head *omfs_get_bucket(struct inode *dir, 25 const char *name, int namelen, int *ofs) 26 { 27 int nbuckets = (dir->i_size - OMFS_DIR_START)/8; 28 int bucket = omfs_hash(name, namelen, nbuckets); 29 30 *ofs = OMFS_DIR_START + bucket * 8; 31 return omfs_bread(dir->i_sb, dir->i_ino); 32 } 33 34 static struct buffer_head *omfs_scan_list(struct inode *dir, u64 block, 35 const char *name, int namelen, 36 u64 *prev_block) 37 { 38 struct buffer_head *bh; 39 struct omfs_inode *oi; 40 int err = -ENOENT; 41 *prev_block = ~0; 42 43 while (block != ~0) { 44 bh = omfs_bread(dir->i_sb, block); 45 if (!bh) { 46 err = -EIO; 47 goto err; 48 } 49 50 oi = (struct omfs_inode *) bh->b_data; 51 if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, block)) { 52 brelse(bh); 53 goto err; 54 } 55 56 if (strncmp(oi->i_name, name, namelen) == 0) 57 return bh; 58 59 *prev_block = block; 60 block = be64_to_cpu(oi->i_sibling); 61 brelse(bh); 62 } 63 err: 64 return ERR_PTR(err); 65 } 66 67 static struct buffer_head *omfs_find_entry(struct inode *dir, 68 const char *name, int namelen) 69 { 70 struct buffer_head *bh; 71 int ofs; 72 u64 block, dummy; 73 74 bh = omfs_get_bucket(dir, name, namelen, &ofs); 75 if (!bh) 76 return ERR_PTR(-EIO); 77 78 block = be64_to_cpu(*((__be64 *) &bh->b_data[ofs])); 79 brelse(bh); 80 81 return omfs_scan_list(dir, block, name, namelen, &dummy); 82 } 83 84 int omfs_make_empty(struct inode *inode, struct super_block *sb) 85 { 86 struct omfs_sb_info *sbi = OMFS_SB(sb); 87 struct buffer_head *bh; 88 struct omfs_inode *oi; 89 90 bh = omfs_bread(sb, inode->i_ino); 91 if (!bh) 92 return -ENOMEM; 93 94 memset(bh->b_data, 0, sizeof(struct omfs_inode)); 95 96 if (inode->i_mode & S_IFDIR) { 97 memset(&bh->b_data[OMFS_DIR_START], 0xff, 98 sbi->s_sys_blocksize - OMFS_DIR_START); 99 } else 100 omfs_make_empty_table(bh, OMFS_EXTENT_START); 101 102 oi = (struct omfs_inode *) bh->b_data; 103 oi->i_head.h_self = cpu_to_be64(inode->i_ino); 104 oi->i_sibling = ~cpu_to_be64(0ULL); 105 106 mark_buffer_dirty(bh); 107 brelse(bh); 108 return 0; 109 } 110 111 static int omfs_add_link(struct dentry *dentry, struct inode *inode) 112 { 113 struct inode *dir = dentry->d_parent->d_inode; 114 const char *name = dentry->d_name.name; 115 int namelen = dentry->d_name.len; 116 struct omfs_inode *oi; 117 struct buffer_head *bh; 118 u64 block; 119 __be64 *entry; 120 int ofs; 121 122 /* just prepend to head of queue in proper bucket */ 123 bh = omfs_get_bucket(dir, name, namelen, &ofs); 124 if (!bh) 125 goto out; 126 127 entry = (__be64 *) &bh->b_data[ofs]; 128 block = be64_to_cpu(*entry); 129 *entry = cpu_to_be64(inode->i_ino); 130 mark_buffer_dirty(bh); 131 brelse(bh); 132 133 /* now set the sibling and parent pointers on the new inode */ 134 bh = omfs_bread(dir->i_sb, inode->i_ino); 135 if (!bh) 136 goto out; 137 138 oi = (struct omfs_inode *) bh->b_data; 139 memcpy(oi->i_name, name, namelen); 140 memset(oi->i_name + namelen, 0, OMFS_NAMELEN - namelen); 141 oi->i_sibling = cpu_to_be64(block); 142 oi->i_parent = cpu_to_be64(dir->i_ino); 143 mark_buffer_dirty(bh); 144 brelse(bh); 145 146 dir->i_ctime = CURRENT_TIME_SEC; 147 148 /* mark affected inodes dirty to rebuild checksums */ 149 mark_inode_dirty(dir); 150 mark_inode_dirty(inode); 151 return 0; 152 out: 153 return -ENOMEM; 154 } 155 156 static int omfs_delete_entry(struct dentry *dentry) 157 { 158 struct inode *dir = dentry->d_parent->d_inode; 159 struct inode *dirty; 160 const char *name = dentry->d_name.name; 161 int namelen = dentry->d_name.len; 162 struct omfs_inode *oi; 163 struct buffer_head *bh, *bh2; 164 __be64 *entry, next; 165 u64 block, prev; 166 int ofs; 167 int err = -ENOMEM; 168 169 /* delete the proper node in the bucket's linked list */ 170 bh = omfs_get_bucket(dir, name, namelen, &ofs); 171 if (!bh) 172 goto out; 173 174 entry = (__be64 *) &bh->b_data[ofs]; 175 block = be64_to_cpu(*entry); 176 177 bh2 = omfs_scan_list(dir, block, name, namelen, &prev); 178 if (IS_ERR(bh2)) { 179 err = PTR_ERR(bh2); 180 goto out_free_bh; 181 } 182 183 oi = (struct omfs_inode *) bh2->b_data; 184 next = oi->i_sibling; 185 brelse(bh2); 186 187 if (prev != ~0) { 188 /* found in middle of list, get list ptr */ 189 brelse(bh); 190 bh = omfs_bread(dir->i_sb, prev); 191 if (!bh) 192 goto out; 193 194 oi = (struct omfs_inode *) bh->b_data; 195 entry = &oi->i_sibling; 196 } 197 198 *entry = next; 199 mark_buffer_dirty(bh); 200 201 if (prev != ~0) { 202 dirty = omfs_iget(dir->i_sb, prev); 203 if (!IS_ERR(dirty)) { 204 mark_inode_dirty(dirty); 205 iput(dirty); 206 } 207 } 208 209 err = 0; 210 out_free_bh: 211 brelse(bh); 212 out: 213 return err; 214 } 215 216 static int omfs_dir_is_empty(struct inode *inode) 217 { 218 int nbuckets = (inode->i_size - OMFS_DIR_START) / 8; 219 struct buffer_head *bh; 220 u64 *ptr; 221 int i; 222 223 bh = omfs_bread(inode->i_sb, inode->i_ino); 224 225 if (!bh) 226 return 0; 227 228 ptr = (u64 *) &bh->b_data[OMFS_DIR_START]; 229 230 for (i = 0; i < nbuckets; i++, ptr++) 231 if (*ptr != ~0) 232 break; 233 234 brelse(bh); 235 return *ptr != ~0; 236 } 237 238 static int omfs_remove(struct inode *dir, struct dentry *dentry) 239 { 240 struct inode *inode = dentry->d_inode; 241 int ret; 242 243 244 if (S_ISDIR(inode->i_mode)) { 245 dentry_unhash(dentry); 246 if (!omfs_dir_is_empty(inode)) 247 return -ENOTEMPTY; 248 } 249 250 ret = omfs_delete_entry(dentry); 251 if (ret) 252 return ret; 253 254 clear_nlink(inode); 255 mark_inode_dirty(inode); 256 mark_inode_dirty(dir); 257 return 0; 258 } 259 260 static int omfs_add_node(struct inode *dir, struct dentry *dentry, int mode) 261 { 262 int err; 263 struct inode *inode = omfs_new_inode(dir, mode); 264 265 if (IS_ERR(inode)) 266 return PTR_ERR(inode); 267 268 err = omfs_make_empty(inode, dir->i_sb); 269 if (err) 270 goto out_free_inode; 271 272 err = omfs_add_link(dentry, inode); 273 if (err) 274 goto out_free_inode; 275 276 d_instantiate(dentry, inode); 277 return 0; 278 279 out_free_inode: 280 iput(inode); 281 return err; 282 } 283 284 static int omfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) 285 { 286 return omfs_add_node(dir, dentry, mode | S_IFDIR); 287 } 288 289 static int omfs_create(struct inode *dir, struct dentry *dentry, int mode, 290 struct nameidata *nd) 291 { 292 return omfs_add_node(dir, dentry, mode | S_IFREG); 293 } 294 295 static struct dentry *omfs_lookup(struct inode *dir, struct dentry *dentry, 296 struct nameidata *nd) 297 { 298 struct buffer_head *bh; 299 struct inode *inode = NULL; 300 301 if (dentry->d_name.len > OMFS_NAMELEN) 302 return ERR_PTR(-ENAMETOOLONG); 303 304 bh = omfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len); 305 if (!IS_ERR(bh)) { 306 struct omfs_inode *oi = (struct omfs_inode *)bh->b_data; 307 ino_t ino = be64_to_cpu(oi->i_head.h_self); 308 brelse(bh); 309 inode = omfs_iget(dir->i_sb, ino); 310 if (IS_ERR(inode)) 311 return ERR_CAST(inode); 312 } 313 d_add(dentry, inode); 314 return NULL; 315 } 316 317 /* sanity check block's self pointer */ 318 int omfs_is_bad(struct omfs_sb_info *sbi, struct omfs_header *header, 319 u64 fsblock) 320 { 321 int is_bad; 322 u64 ino = be64_to_cpu(header->h_self); 323 is_bad = ((ino != fsblock) || (ino < sbi->s_root_ino) || 324 (ino > sbi->s_num_blocks)); 325 326 if (is_bad) 327 printk(KERN_WARNING "omfs: bad hash chain detected\n"); 328 329 return is_bad; 330 } 331 332 static int omfs_fill_chain(struct file *filp, void *dirent, filldir_t filldir, 333 u64 fsblock, int hindex) 334 { 335 struct inode *dir = filp->f_dentry->d_inode; 336 struct buffer_head *bh; 337 struct omfs_inode *oi; 338 u64 self; 339 int res = 0; 340 unsigned char d_type; 341 342 /* follow chain in this bucket */ 343 while (fsblock != ~0) { 344 bh = omfs_bread(dir->i_sb, fsblock); 345 if (!bh) 346 goto out; 347 348 oi = (struct omfs_inode *) bh->b_data; 349 if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, fsblock)) { 350 brelse(bh); 351 goto out; 352 } 353 354 self = fsblock; 355 fsblock = be64_to_cpu(oi->i_sibling); 356 357 /* skip visited nodes */ 358 if (hindex) { 359 hindex--; 360 brelse(bh); 361 continue; 362 } 363 364 d_type = (oi->i_type == OMFS_DIR) ? DT_DIR : DT_REG; 365 366 res = filldir(dirent, oi->i_name, strnlen(oi->i_name, 367 OMFS_NAMELEN), filp->f_pos, self, d_type); 368 brelse(bh); 369 if (res < 0) 370 break; 371 filp->f_pos++; 372 } 373 out: 374 return res; 375 } 376 377 static int omfs_rename(struct inode *old_dir, struct dentry *old_dentry, 378 struct inode *new_dir, struct dentry *new_dentry) 379 { 380 struct inode *new_inode = new_dentry->d_inode; 381 struct inode *old_inode = old_dentry->d_inode; 382 int err; 383 384 if (new_inode) { 385 /* overwriting existing file/dir */ 386 err = omfs_remove(new_dir, new_dentry); 387 if (err) 388 goto out; 389 } 390 391 /* since omfs locates files by name, we need to unlink _before_ 392 * adding the new link or we won't find the old one */ 393 err = omfs_delete_entry(old_dentry); 394 if (err) 395 goto out; 396 397 mark_inode_dirty(old_dir); 398 err = omfs_add_link(new_dentry, old_inode); 399 if (err) 400 goto out; 401 402 old_inode->i_ctime = CURRENT_TIME_SEC; 403 mark_inode_dirty(old_inode); 404 out: 405 return err; 406 } 407 408 static int omfs_readdir(struct file *filp, void *dirent, filldir_t filldir) 409 { 410 struct inode *dir = filp->f_dentry->d_inode; 411 struct buffer_head *bh; 412 loff_t offset, res; 413 unsigned int hchain, hindex; 414 int nbuckets; 415 u64 fsblock; 416 int ret = -EINVAL; 417 418 if (filp->f_pos >> 32) 419 goto success; 420 421 switch ((unsigned long) filp->f_pos) { 422 case 0: 423 if (filldir(dirent, ".", 1, 0, dir->i_ino, DT_DIR) < 0) 424 goto success; 425 filp->f_pos++; 426 /* fall through */ 427 case 1: 428 if (filldir(dirent, "..", 2, 1, 429 parent_ino(filp->f_dentry), DT_DIR) < 0) 430 goto success; 431 filp->f_pos = 1 << 20; 432 /* fall through */ 433 } 434 435 nbuckets = (dir->i_size - OMFS_DIR_START) / 8; 436 437 /* high 12 bits store bucket + 1 and low 20 bits store hash index */ 438 hchain = (filp->f_pos >> 20) - 1; 439 hindex = filp->f_pos & 0xfffff; 440 441 bh = omfs_bread(dir->i_sb, dir->i_ino); 442 if (!bh) 443 goto out; 444 445 offset = OMFS_DIR_START + hchain * 8; 446 447 for (; hchain < nbuckets; hchain++, offset += 8) { 448 fsblock = be64_to_cpu(*((__be64 *) &bh->b_data[offset])); 449 450 res = omfs_fill_chain(filp, dirent, filldir, fsblock, hindex); 451 hindex = 0; 452 if (res < 0) 453 break; 454 455 filp->f_pos = (hchain+2) << 20; 456 } 457 brelse(bh); 458 success: 459 ret = 0; 460 out: 461 return ret; 462 } 463 464 const struct inode_operations omfs_dir_inops = { 465 .lookup = omfs_lookup, 466 .mkdir = omfs_mkdir, 467 .rename = omfs_rename, 468 .create = omfs_create, 469 .unlink = omfs_remove, 470 .rmdir = omfs_remove, 471 }; 472 473 const struct file_operations omfs_dir_operations = { 474 .read = generic_read_dir, 475 .readdir = omfs_readdir, 476 .llseek = generic_file_llseek, 477 }; 478