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 if (S_ISDIR(inode->i_mode) && !omfs_dir_is_empty(inode)) 244 return -ENOTEMPTY; 245 246 ret = omfs_delete_entry(dentry); 247 if (ret) 248 return ret; 249 250 clear_nlink(inode); 251 mark_inode_dirty(inode); 252 mark_inode_dirty(dir); 253 return 0; 254 } 255 256 static int omfs_add_node(struct inode *dir, struct dentry *dentry, int mode) 257 { 258 int err; 259 struct inode *inode = omfs_new_inode(dir, mode); 260 261 if (IS_ERR(inode)) 262 return PTR_ERR(inode); 263 264 err = omfs_make_empty(inode, dir->i_sb); 265 if (err) 266 goto out_free_inode; 267 268 err = omfs_add_link(dentry, inode); 269 if (err) 270 goto out_free_inode; 271 272 d_instantiate(dentry, inode); 273 return 0; 274 275 out_free_inode: 276 iput(inode); 277 return err; 278 } 279 280 static int omfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) 281 { 282 return omfs_add_node(dir, dentry, mode | S_IFDIR); 283 } 284 285 static int omfs_create(struct inode *dir, struct dentry *dentry, int mode, 286 struct nameidata *nd) 287 { 288 return omfs_add_node(dir, dentry, mode | S_IFREG); 289 } 290 291 static struct dentry *omfs_lookup(struct inode *dir, struct dentry *dentry, 292 struct nameidata *nd) 293 { 294 struct buffer_head *bh; 295 struct inode *inode = NULL; 296 297 if (dentry->d_name.len > OMFS_NAMELEN) 298 return ERR_PTR(-ENAMETOOLONG); 299 300 bh = omfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len); 301 if (!IS_ERR(bh)) { 302 struct omfs_inode *oi = (struct omfs_inode *)bh->b_data; 303 ino_t ino = be64_to_cpu(oi->i_head.h_self); 304 brelse(bh); 305 inode = omfs_iget(dir->i_sb, ino); 306 if (IS_ERR(inode)) 307 return ERR_CAST(inode); 308 } 309 d_add(dentry, inode); 310 return NULL; 311 } 312 313 /* sanity check block's self pointer */ 314 int omfs_is_bad(struct omfs_sb_info *sbi, struct omfs_header *header, 315 u64 fsblock) 316 { 317 int is_bad; 318 u64 ino = be64_to_cpu(header->h_self); 319 is_bad = ((ino != fsblock) || (ino < sbi->s_root_ino) || 320 (ino > sbi->s_num_blocks)); 321 322 if (is_bad) 323 printk(KERN_WARNING "omfs: bad hash chain detected\n"); 324 325 return is_bad; 326 } 327 328 static int omfs_fill_chain(struct file *filp, void *dirent, filldir_t filldir, 329 u64 fsblock, int hindex) 330 { 331 struct inode *dir = filp->f_dentry->d_inode; 332 struct buffer_head *bh; 333 struct omfs_inode *oi; 334 u64 self; 335 int res = 0; 336 unsigned char d_type; 337 338 /* follow chain in this bucket */ 339 while (fsblock != ~0) { 340 bh = omfs_bread(dir->i_sb, fsblock); 341 if (!bh) 342 goto out; 343 344 oi = (struct omfs_inode *) bh->b_data; 345 if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, fsblock)) { 346 brelse(bh); 347 goto out; 348 } 349 350 self = fsblock; 351 fsblock = be64_to_cpu(oi->i_sibling); 352 353 /* skip visited nodes */ 354 if (hindex) { 355 hindex--; 356 brelse(bh); 357 continue; 358 } 359 360 d_type = (oi->i_type == OMFS_DIR) ? DT_DIR : DT_REG; 361 362 res = filldir(dirent, oi->i_name, strnlen(oi->i_name, 363 OMFS_NAMELEN), filp->f_pos, self, d_type); 364 if (res == 0) 365 filp->f_pos++; 366 brelse(bh); 367 } 368 out: 369 return res; 370 } 371 372 static int omfs_rename(struct inode *old_dir, struct dentry *old_dentry, 373 struct inode *new_dir, struct dentry *new_dentry) 374 { 375 struct inode *new_inode = new_dentry->d_inode; 376 struct inode *old_inode = old_dentry->d_inode; 377 int err; 378 379 if (new_inode) { 380 /* overwriting existing file/dir */ 381 err = omfs_remove(new_dir, new_dentry); 382 if (err) 383 goto out; 384 } 385 386 /* since omfs locates files by name, we need to unlink _before_ 387 * adding the new link or we won't find the old one */ 388 err = omfs_delete_entry(old_dentry); 389 if (err) 390 goto out; 391 392 mark_inode_dirty(old_dir); 393 err = omfs_add_link(new_dentry, old_inode); 394 if (err) 395 goto out; 396 397 old_inode->i_ctime = CURRENT_TIME_SEC; 398 mark_inode_dirty(old_inode); 399 out: 400 return err; 401 } 402 403 static int omfs_readdir(struct file *filp, void *dirent, filldir_t filldir) 404 { 405 struct inode *dir = filp->f_dentry->d_inode; 406 struct buffer_head *bh; 407 loff_t offset, res; 408 unsigned int hchain, hindex; 409 int nbuckets; 410 u64 fsblock; 411 int ret = -EINVAL; 412 413 if (filp->f_pos >> 32) 414 goto success; 415 416 switch ((unsigned long) filp->f_pos) { 417 case 0: 418 if (filldir(dirent, ".", 1, 0, dir->i_ino, DT_DIR) < 0) 419 goto success; 420 filp->f_pos++; 421 /* fall through */ 422 case 1: 423 if (filldir(dirent, "..", 2, 1, 424 parent_ino(filp->f_dentry), DT_DIR) < 0) 425 goto success; 426 filp->f_pos = 1 << 20; 427 /* fall through */ 428 } 429 430 nbuckets = (dir->i_size - OMFS_DIR_START) / 8; 431 432 /* high 12 bits store bucket + 1 and low 20 bits store hash index */ 433 hchain = (filp->f_pos >> 20) - 1; 434 hindex = filp->f_pos & 0xfffff; 435 436 bh = omfs_bread(dir->i_sb, dir->i_ino); 437 if (!bh) 438 goto out; 439 440 offset = OMFS_DIR_START + hchain * 8; 441 442 for (; hchain < nbuckets; hchain++, offset += 8) { 443 fsblock = be64_to_cpu(*((__be64 *) &bh->b_data[offset])); 444 445 res = omfs_fill_chain(filp, dirent, filldir, fsblock, hindex); 446 hindex = 0; 447 if (res < 0) 448 break; 449 450 filp->f_pos = (hchain+2) << 20; 451 } 452 brelse(bh); 453 success: 454 ret = 0; 455 out: 456 return ret; 457 } 458 459 const struct inode_operations omfs_dir_inops = { 460 .lookup = omfs_lookup, 461 .mkdir = omfs_mkdir, 462 .rename = omfs_rename, 463 .create = omfs_create, 464 .unlink = omfs_remove, 465 .rmdir = omfs_remove, 466 }; 467 468 const struct file_operations omfs_dir_operations = { 469 .read = generic_read_dir, 470 .readdir = omfs_readdir, 471 .llseek = generic_file_llseek, 472 }; 473