1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * OMFS (as used by RIO Karma) directory operations. 4 * Copyright (C) 2005 Bob Copeland <me@bobcopeland.com> 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 (S_ISDIR(inode->i_mode)) { 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 = d_inode(dentry->d_parent); 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 inode_set_ctime_current(dir); 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 = d_inode(dentry->d_parent); 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 = d_inode(dentry); 241 int ret; 242 243 244 if (S_ISDIR(inode->i_mode) && 245 !omfs_dir_is_empty(inode)) 246 return -ENOTEMPTY; 247 248 ret = omfs_delete_entry(dentry); 249 if (ret) 250 return ret; 251 252 clear_nlink(inode); 253 mark_inode_dirty(inode); 254 mark_inode_dirty(dir); 255 return 0; 256 } 257 258 static int omfs_add_node(struct inode *dir, struct dentry *dentry, umode_t mode) 259 { 260 int err; 261 struct inode *inode = omfs_new_inode(dir, mode); 262 263 if (IS_ERR(inode)) 264 return PTR_ERR(inode); 265 266 err = omfs_make_empty(inode, dir->i_sb); 267 if (err) 268 goto out_free_inode; 269 270 err = omfs_add_link(dentry, inode); 271 if (err) 272 goto out_free_inode; 273 274 d_instantiate(dentry, inode); 275 return 0; 276 277 out_free_inode: 278 iput(inode); 279 return err; 280 } 281 282 static int omfs_mkdir(struct mnt_idmap *idmap, struct inode *dir, 283 struct dentry *dentry, umode_t mode) 284 { 285 return omfs_add_node(dir, dentry, mode | S_IFDIR); 286 } 287 288 static int omfs_create(struct mnt_idmap *idmap, struct inode *dir, 289 struct dentry *dentry, umode_t mode, bool excl) 290 { 291 return omfs_add_node(dir, dentry, mode | S_IFREG); 292 } 293 294 static struct dentry *omfs_lookup(struct inode *dir, struct dentry *dentry, 295 unsigned int flags) 296 { 297 struct buffer_head *bh; 298 struct inode *inode = NULL; 299 300 if (dentry->d_name.len > OMFS_NAMELEN) 301 return ERR_PTR(-ENAMETOOLONG); 302 303 bh = omfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len); 304 if (!IS_ERR(bh)) { 305 struct omfs_inode *oi = (struct omfs_inode *)bh->b_data; 306 ino_t ino = be64_to_cpu(oi->i_head.h_self); 307 brelse(bh); 308 inode = omfs_iget(dir->i_sb, ino); 309 } else if (bh != ERR_PTR(-ENOENT)) { 310 inode = ERR_CAST(bh); 311 } 312 return d_splice_alias(inode, dentry); 313 } 314 315 /* sanity check block's self pointer */ 316 int omfs_is_bad(struct omfs_sb_info *sbi, struct omfs_header *header, 317 u64 fsblock) 318 { 319 int is_bad; 320 u64 ino = be64_to_cpu(header->h_self); 321 is_bad = ((ino != fsblock) || (ino < sbi->s_root_ino) || 322 (ino > sbi->s_num_blocks)); 323 324 if (is_bad) 325 printk(KERN_WARNING "omfs: bad hash chain detected\n"); 326 327 return is_bad; 328 } 329 330 static bool omfs_fill_chain(struct inode *dir, struct dir_context *ctx, 331 u64 fsblock, int hindex) 332 { 333 /* follow chain in this bucket */ 334 while (fsblock != ~0) { 335 struct buffer_head *bh = omfs_bread(dir->i_sb, fsblock); 336 struct omfs_inode *oi; 337 u64 self; 338 unsigned char d_type; 339 340 if (!bh) 341 return true; 342 343 oi = (struct omfs_inode *) bh->b_data; 344 if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, fsblock)) { 345 brelse(bh); 346 return true; 347 } 348 349 self = fsblock; 350 fsblock = be64_to_cpu(oi->i_sibling); 351 352 /* skip visited nodes */ 353 if (hindex) { 354 hindex--; 355 brelse(bh); 356 continue; 357 } 358 359 d_type = (oi->i_type == OMFS_DIR) ? DT_DIR : DT_REG; 360 361 if (!dir_emit(ctx, oi->i_name, 362 strnlen(oi->i_name, OMFS_NAMELEN), 363 self, d_type)) { 364 brelse(bh); 365 return false; 366 } 367 brelse(bh); 368 ctx->pos++; 369 } 370 return true; 371 } 372 373 static int omfs_rename(struct mnt_idmap *idmap, struct inode *old_dir, 374 struct dentry *old_dentry, struct inode *new_dir, 375 struct dentry *new_dentry, unsigned int flags) 376 { 377 struct inode *new_inode = d_inode(new_dentry); 378 struct inode *old_inode = d_inode(old_dentry); 379 int err; 380 381 if (flags & ~RENAME_NOREPLACE) 382 return -EINVAL; 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 inode_set_ctime_current(old_inode); 403 mark_inode_dirty(old_inode); 404 out: 405 return err; 406 } 407 408 static int omfs_readdir(struct file *file, struct dir_context *ctx) 409 { 410 struct inode *dir = file_inode(file); 411 struct buffer_head *bh; 412 __be64 *p; 413 unsigned int hchain, hindex; 414 int nbuckets; 415 416 if (ctx->pos >> 32) 417 return -EINVAL; 418 419 if (ctx->pos < 1 << 20) { 420 if (!dir_emit_dots(file, ctx)) 421 return 0; 422 ctx->pos = 1 << 20; 423 } 424 425 nbuckets = (dir->i_size - OMFS_DIR_START) / 8; 426 427 /* high 12 bits store bucket + 1 and low 20 bits store hash index */ 428 hchain = (ctx->pos >> 20) - 1; 429 hindex = ctx->pos & 0xfffff; 430 431 bh = omfs_bread(dir->i_sb, dir->i_ino); 432 if (!bh) 433 return -EINVAL; 434 435 p = (__be64 *)(bh->b_data + OMFS_DIR_START) + hchain; 436 437 for (; hchain < nbuckets; hchain++) { 438 __u64 fsblock = be64_to_cpu(*p++); 439 if (!omfs_fill_chain(dir, ctx, fsblock, hindex)) 440 break; 441 hindex = 0; 442 ctx->pos = (hchain+2) << 20; 443 } 444 brelse(bh); 445 return 0; 446 } 447 448 const struct inode_operations omfs_dir_inops = { 449 .lookup = omfs_lookup, 450 .mkdir = omfs_mkdir, 451 .rename = omfs_rename, 452 .create = omfs_create, 453 .unlink = omfs_remove, 454 .rmdir = omfs_remove, 455 }; 456 457 const struct file_operations omfs_dir_operations = { 458 .read = generic_read_dir, 459 .iterate_shared = omfs_readdir, 460 .llseek = generic_file_llseek, 461 }; 462