1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2011 Novell Inc. 4 * Copyright (C) 2016 Red Hat, Inc. 5 */ 6 7 #include <linux/fs.h> 8 #include <linux/mount.h> 9 #include <linux/slab.h> 10 #include <linux/cred.h> 11 #include <linux/xattr.h> 12 #include <linux/exportfs.h> 13 #include <linux/uuid.h> 14 #include <linux/namei.h> 15 #include <linux/ratelimit.h> 16 #include "overlayfs.h" 17 18 int ovl_want_write(struct dentry *dentry) 19 { 20 struct ovl_fs *ofs = dentry->d_sb->s_fs_info; 21 return mnt_want_write(ofs->upper_mnt); 22 } 23 24 void ovl_drop_write(struct dentry *dentry) 25 { 26 struct ovl_fs *ofs = dentry->d_sb->s_fs_info; 27 mnt_drop_write(ofs->upper_mnt); 28 } 29 30 struct dentry *ovl_workdir(struct dentry *dentry) 31 { 32 struct ovl_fs *ofs = dentry->d_sb->s_fs_info; 33 return ofs->workdir; 34 } 35 36 const struct cred *ovl_override_creds(struct super_block *sb) 37 { 38 struct ovl_fs *ofs = sb->s_fs_info; 39 40 return override_creds(ofs->creator_cred); 41 } 42 43 /* 44 * Check if underlying fs supports file handles and try to determine encoding 45 * type, in order to deduce maximum inode number used by fs. 46 * 47 * Return 0 if file handles are not supported. 48 * Return 1 (FILEID_INO32_GEN) if fs uses the default 32bit inode encoding. 49 * Return -1 if fs uses a non default encoding with unknown inode size. 50 */ 51 int ovl_can_decode_fh(struct super_block *sb) 52 { 53 if (!sb->s_export_op || !sb->s_export_op->fh_to_dentry) 54 return 0; 55 56 return sb->s_export_op->encode_fh ? -1 : FILEID_INO32_GEN; 57 } 58 59 struct dentry *ovl_indexdir(struct super_block *sb) 60 { 61 struct ovl_fs *ofs = sb->s_fs_info; 62 63 return ofs->indexdir; 64 } 65 66 /* Index all files on copy up. For now only enabled for NFS export */ 67 bool ovl_index_all(struct super_block *sb) 68 { 69 struct ovl_fs *ofs = sb->s_fs_info; 70 71 return ofs->config.nfs_export && ofs->config.index; 72 } 73 74 /* Verify lower origin on lookup. For now only enabled for NFS export */ 75 bool ovl_verify_lower(struct super_block *sb) 76 { 77 struct ovl_fs *ofs = sb->s_fs_info; 78 79 return ofs->config.nfs_export && ofs->config.index; 80 } 81 82 struct ovl_entry *ovl_alloc_entry(unsigned int numlower) 83 { 84 size_t size = offsetof(struct ovl_entry, lowerstack[numlower]); 85 struct ovl_entry *oe = kzalloc(size, GFP_KERNEL); 86 87 if (oe) 88 oe->numlower = numlower; 89 90 return oe; 91 } 92 93 bool ovl_dentry_remote(struct dentry *dentry) 94 { 95 return dentry->d_flags & 96 (DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE | 97 DCACHE_OP_REAL); 98 } 99 100 bool ovl_dentry_weird(struct dentry *dentry) 101 { 102 return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT | 103 DCACHE_MANAGE_TRANSIT | 104 DCACHE_OP_HASH | 105 DCACHE_OP_COMPARE); 106 } 107 108 enum ovl_path_type ovl_path_type(struct dentry *dentry) 109 { 110 struct ovl_entry *oe = dentry->d_fsdata; 111 enum ovl_path_type type = 0; 112 113 if (ovl_dentry_upper(dentry)) { 114 type = __OVL_PATH_UPPER; 115 116 /* 117 * Non-dir dentry can hold lower dentry of its copy up origin. 118 */ 119 if (oe->numlower) { 120 if (ovl_test_flag(OVL_CONST_INO, d_inode(dentry))) 121 type |= __OVL_PATH_ORIGIN; 122 if (d_is_dir(dentry) || 123 !ovl_has_upperdata(d_inode(dentry))) 124 type |= __OVL_PATH_MERGE; 125 } 126 } else { 127 if (oe->numlower > 1) 128 type |= __OVL_PATH_MERGE; 129 } 130 return type; 131 } 132 133 void ovl_path_upper(struct dentry *dentry, struct path *path) 134 { 135 struct ovl_fs *ofs = dentry->d_sb->s_fs_info; 136 137 path->mnt = ofs->upper_mnt; 138 path->dentry = ovl_dentry_upper(dentry); 139 } 140 141 void ovl_path_lower(struct dentry *dentry, struct path *path) 142 { 143 struct ovl_entry *oe = dentry->d_fsdata; 144 145 if (oe->numlower) { 146 path->mnt = oe->lowerstack[0].layer->mnt; 147 path->dentry = oe->lowerstack[0].dentry; 148 } else { 149 *path = (struct path) { }; 150 } 151 } 152 153 void ovl_path_lowerdata(struct dentry *dentry, struct path *path) 154 { 155 struct ovl_entry *oe = dentry->d_fsdata; 156 157 if (oe->numlower) { 158 path->mnt = oe->lowerstack[oe->numlower - 1].layer->mnt; 159 path->dentry = oe->lowerstack[oe->numlower - 1].dentry; 160 } else { 161 *path = (struct path) { }; 162 } 163 } 164 165 enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path) 166 { 167 enum ovl_path_type type = ovl_path_type(dentry); 168 169 if (!OVL_TYPE_UPPER(type)) 170 ovl_path_lower(dentry, path); 171 else 172 ovl_path_upper(dentry, path); 173 174 return type; 175 } 176 177 struct dentry *ovl_dentry_upper(struct dentry *dentry) 178 { 179 return ovl_upperdentry_dereference(OVL_I(d_inode(dentry))); 180 } 181 182 struct dentry *ovl_dentry_lower(struct dentry *dentry) 183 { 184 struct ovl_entry *oe = dentry->d_fsdata; 185 186 return oe->numlower ? oe->lowerstack[0].dentry : NULL; 187 } 188 189 const struct ovl_layer *ovl_layer_lower(struct dentry *dentry) 190 { 191 struct ovl_entry *oe = dentry->d_fsdata; 192 193 return oe->numlower ? oe->lowerstack[0].layer : NULL; 194 } 195 196 /* 197 * ovl_dentry_lower() could return either a data dentry or metacopy dentry 198 * dependig on what is stored in lowerstack[0]. At times we need to find 199 * lower dentry which has data (and not metacopy dentry). This helper 200 * returns the lower data dentry. 201 */ 202 struct dentry *ovl_dentry_lowerdata(struct dentry *dentry) 203 { 204 struct ovl_entry *oe = dentry->d_fsdata; 205 206 return oe->numlower ? oe->lowerstack[oe->numlower - 1].dentry : NULL; 207 } 208 209 struct dentry *ovl_dentry_real(struct dentry *dentry) 210 { 211 return ovl_dentry_upper(dentry) ?: ovl_dentry_lower(dentry); 212 } 213 214 struct dentry *ovl_i_dentry_upper(struct inode *inode) 215 { 216 return ovl_upperdentry_dereference(OVL_I(inode)); 217 } 218 219 struct inode *ovl_inode_upper(struct inode *inode) 220 { 221 struct dentry *upperdentry = ovl_i_dentry_upper(inode); 222 223 return upperdentry ? d_inode(upperdentry) : NULL; 224 } 225 226 struct inode *ovl_inode_lower(struct inode *inode) 227 { 228 return OVL_I(inode)->lower; 229 } 230 231 struct inode *ovl_inode_real(struct inode *inode) 232 { 233 return ovl_inode_upper(inode) ?: ovl_inode_lower(inode); 234 } 235 236 /* Return inode which contains lower data. Do not return metacopy */ 237 struct inode *ovl_inode_lowerdata(struct inode *inode) 238 { 239 if (WARN_ON(!S_ISREG(inode->i_mode))) 240 return NULL; 241 242 return OVL_I(inode)->lowerdata ?: ovl_inode_lower(inode); 243 } 244 245 /* Return real inode which contains data. Does not return metacopy inode */ 246 struct inode *ovl_inode_realdata(struct inode *inode) 247 { 248 struct inode *upperinode; 249 250 upperinode = ovl_inode_upper(inode); 251 if (upperinode && ovl_has_upperdata(inode)) 252 return upperinode; 253 254 return ovl_inode_lowerdata(inode); 255 } 256 257 struct ovl_dir_cache *ovl_dir_cache(struct inode *inode) 258 { 259 return OVL_I(inode)->cache; 260 } 261 262 void ovl_set_dir_cache(struct inode *inode, struct ovl_dir_cache *cache) 263 { 264 OVL_I(inode)->cache = cache; 265 } 266 267 void ovl_dentry_set_flag(unsigned long flag, struct dentry *dentry) 268 { 269 set_bit(flag, &OVL_E(dentry)->flags); 270 } 271 272 void ovl_dentry_clear_flag(unsigned long flag, struct dentry *dentry) 273 { 274 clear_bit(flag, &OVL_E(dentry)->flags); 275 } 276 277 bool ovl_dentry_test_flag(unsigned long flag, struct dentry *dentry) 278 { 279 return test_bit(flag, &OVL_E(dentry)->flags); 280 } 281 282 bool ovl_dentry_is_opaque(struct dentry *dentry) 283 { 284 return ovl_dentry_test_flag(OVL_E_OPAQUE, dentry); 285 } 286 287 bool ovl_dentry_is_whiteout(struct dentry *dentry) 288 { 289 return !dentry->d_inode && ovl_dentry_is_opaque(dentry); 290 } 291 292 void ovl_dentry_set_opaque(struct dentry *dentry) 293 { 294 ovl_dentry_set_flag(OVL_E_OPAQUE, dentry); 295 } 296 297 /* 298 * For hard links and decoded file handles, it's possible for ovl_dentry_upper() 299 * to return positive, while there's no actual upper alias for the inode. 300 * Copy up code needs to know about the existence of the upper alias, so it 301 * can't use ovl_dentry_upper(). 302 */ 303 bool ovl_dentry_has_upper_alias(struct dentry *dentry) 304 { 305 return ovl_dentry_test_flag(OVL_E_UPPER_ALIAS, dentry); 306 } 307 308 void ovl_dentry_set_upper_alias(struct dentry *dentry) 309 { 310 ovl_dentry_set_flag(OVL_E_UPPER_ALIAS, dentry); 311 } 312 313 static bool ovl_should_check_upperdata(struct inode *inode) 314 { 315 if (!S_ISREG(inode->i_mode)) 316 return false; 317 318 if (!ovl_inode_lower(inode)) 319 return false; 320 321 return true; 322 } 323 324 bool ovl_has_upperdata(struct inode *inode) 325 { 326 if (!ovl_should_check_upperdata(inode)) 327 return true; 328 329 if (!ovl_test_flag(OVL_UPPERDATA, inode)) 330 return false; 331 /* 332 * Pairs with smp_wmb() in ovl_set_upperdata(). Main user of 333 * ovl_has_upperdata() is ovl_copy_up_meta_inode_data(). Make sure 334 * if setting of OVL_UPPERDATA is visible, then effects of writes 335 * before that are visible too. 336 */ 337 smp_rmb(); 338 return true; 339 } 340 341 void ovl_set_upperdata(struct inode *inode) 342 { 343 /* 344 * Pairs with smp_rmb() in ovl_has_upperdata(). Make sure 345 * if OVL_UPPERDATA flag is visible, then effects of write operations 346 * before it are visible as well. 347 */ 348 smp_wmb(); 349 ovl_set_flag(OVL_UPPERDATA, inode); 350 } 351 352 /* Caller should hold ovl_inode->lock */ 353 bool ovl_dentry_needs_data_copy_up_locked(struct dentry *dentry, int flags) 354 { 355 if (!ovl_open_flags_need_copy_up(flags)) 356 return false; 357 358 return !ovl_test_flag(OVL_UPPERDATA, d_inode(dentry)); 359 } 360 361 bool ovl_dentry_needs_data_copy_up(struct dentry *dentry, int flags) 362 { 363 if (!ovl_open_flags_need_copy_up(flags)) 364 return false; 365 366 return !ovl_has_upperdata(d_inode(dentry)); 367 } 368 369 bool ovl_redirect_dir(struct super_block *sb) 370 { 371 struct ovl_fs *ofs = sb->s_fs_info; 372 373 return ofs->config.redirect_dir && !ofs->noxattr; 374 } 375 376 const char *ovl_dentry_get_redirect(struct dentry *dentry) 377 { 378 return OVL_I(d_inode(dentry))->redirect; 379 } 380 381 void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect) 382 { 383 struct ovl_inode *oi = OVL_I(d_inode(dentry)); 384 385 kfree(oi->redirect); 386 oi->redirect = redirect; 387 } 388 389 void ovl_inode_init(struct inode *inode, struct dentry *upperdentry, 390 struct dentry *lowerdentry, struct dentry *lowerdata) 391 { 392 struct inode *realinode = d_inode(upperdentry ?: lowerdentry); 393 394 if (upperdentry) 395 OVL_I(inode)->__upperdentry = upperdentry; 396 if (lowerdentry) 397 OVL_I(inode)->lower = igrab(d_inode(lowerdentry)); 398 if (lowerdata) 399 OVL_I(inode)->lowerdata = igrab(d_inode(lowerdata)); 400 401 ovl_copyattr(realinode, inode); 402 ovl_copyflags(realinode, inode); 403 if (!inode->i_ino) 404 inode->i_ino = realinode->i_ino; 405 } 406 407 void ovl_inode_update(struct inode *inode, struct dentry *upperdentry) 408 { 409 struct inode *upperinode = d_inode(upperdentry); 410 411 WARN_ON(OVL_I(inode)->__upperdentry); 412 413 /* 414 * Make sure upperdentry is consistent before making it visible 415 */ 416 smp_wmb(); 417 OVL_I(inode)->__upperdentry = upperdentry; 418 if (inode_unhashed(inode)) { 419 if (!inode->i_ino) 420 inode->i_ino = upperinode->i_ino; 421 inode->i_private = upperinode; 422 __insert_inode_hash(inode, (unsigned long) upperinode); 423 } 424 } 425 426 static void ovl_dentry_version_inc(struct dentry *dentry, bool impurity) 427 { 428 struct inode *inode = d_inode(dentry); 429 430 WARN_ON(!inode_is_locked(inode)); 431 /* 432 * Version is used by readdir code to keep cache consistent. For merge 433 * dirs all changes need to be noted. For non-merge dirs, cache only 434 * contains impure (ones which have been copied up and have origins) 435 * entries, so only need to note changes to impure entries. 436 */ 437 if (OVL_TYPE_MERGE(ovl_path_type(dentry)) || impurity) 438 OVL_I(inode)->version++; 439 } 440 441 void ovl_dir_modified(struct dentry *dentry, bool impurity) 442 { 443 /* Copy mtime/ctime */ 444 ovl_copyattr(d_inode(ovl_dentry_upper(dentry)), d_inode(dentry)); 445 446 ovl_dentry_version_inc(dentry, impurity); 447 } 448 449 u64 ovl_dentry_version_get(struct dentry *dentry) 450 { 451 struct inode *inode = d_inode(dentry); 452 453 WARN_ON(!inode_is_locked(inode)); 454 return OVL_I(inode)->version; 455 } 456 457 bool ovl_is_whiteout(struct dentry *dentry) 458 { 459 struct inode *inode = dentry->d_inode; 460 461 return inode && IS_WHITEOUT(inode); 462 } 463 464 struct file *ovl_path_open(struct path *path, int flags) 465 { 466 return dentry_open(path, flags | O_NOATIME, current_cred()); 467 } 468 469 /* Caller should hold ovl_inode->lock */ 470 static bool ovl_already_copied_up_locked(struct dentry *dentry, int flags) 471 { 472 bool disconnected = dentry->d_flags & DCACHE_DISCONNECTED; 473 474 if (ovl_dentry_upper(dentry) && 475 (ovl_dentry_has_upper_alias(dentry) || disconnected) && 476 !ovl_dentry_needs_data_copy_up_locked(dentry, flags)) 477 return true; 478 479 return false; 480 } 481 482 bool ovl_already_copied_up(struct dentry *dentry, int flags) 483 { 484 bool disconnected = dentry->d_flags & DCACHE_DISCONNECTED; 485 486 /* 487 * Check if copy-up has happened as well as for upper alias (in 488 * case of hard links) is there. 489 * 490 * Both checks are lockless: 491 * - false negatives: will recheck under oi->lock 492 * - false positives: 493 * + ovl_dentry_upper() uses memory barriers to ensure the 494 * upper dentry is up-to-date 495 * + ovl_dentry_has_upper_alias() relies on locking of 496 * upper parent i_rwsem to prevent reordering copy-up 497 * with rename. 498 */ 499 if (ovl_dentry_upper(dentry) && 500 (ovl_dentry_has_upper_alias(dentry) || disconnected) && 501 !ovl_dentry_needs_data_copy_up(dentry, flags)) 502 return true; 503 504 return false; 505 } 506 507 int ovl_copy_up_start(struct dentry *dentry, int flags) 508 { 509 struct inode *inode = d_inode(dentry); 510 int err; 511 512 err = ovl_inode_lock(inode); 513 if (!err && ovl_already_copied_up_locked(dentry, flags)) { 514 err = 1; /* Already copied up */ 515 ovl_inode_unlock(inode); 516 } 517 518 return err; 519 } 520 521 void ovl_copy_up_end(struct dentry *dentry) 522 { 523 ovl_inode_unlock(d_inode(dentry)); 524 } 525 526 bool ovl_check_origin_xattr(struct dentry *dentry) 527 { 528 int res; 529 530 res = vfs_getxattr(dentry, OVL_XATTR_ORIGIN, NULL, 0); 531 532 /* Zero size value means "copied up but origin unknown" */ 533 if (res >= 0) 534 return true; 535 536 return false; 537 } 538 539 bool ovl_check_dir_xattr(struct dentry *dentry, const char *name) 540 { 541 int res; 542 char val; 543 544 if (!d_is_dir(dentry)) 545 return false; 546 547 res = vfs_getxattr(dentry, name, &val, 1); 548 if (res == 1 && val == 'y') 549 return true; 550 551 return false; 552 } 553 554 int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry, 555 const char *name, const void *value, size_t size, 556 int xerr) 557 { 558 int err; 559 struct ovl_fs *ofs = dentry->d_sb->s_fs_info; 560 561 if (ofs->noxattr) 562 return xerr; 563 564 err = ovl_do_setxattr(upperdentry, name, value, size, 0); 565 566 if (err == -EOPNOTSUPP) { 567 pr_warn("cannot set %s xattr on upper\n", name); 568 ofs->noxattr = true; 569 return xerr; 570 } 571 572 return err; 573 } 574 575 int ovl_set_impure(struct dentry *dentry, struct dentry *upperdentry) 576 { 577 int err; 578 579 if (ovl_test_flag(OVL_IMPURE, d_inode(dentry))) 580 return 0; 581 582 /* 583 * Do not fail when upper doesn't support xattrs. 584 * Upper inodes won't have origin nor redirect xattr anyway. 585 */ 586 err = ovl_check_setxattr(dentry, upperdentry, OVL_XATTR_IMPURE, 587 "y", 1, 0); 588 if (!err) 589 ovl_set_flag(OVL_IMPURE, d_inode(dentry)); 590 591 return err; 592 } 593 594 void ovl_set_flag(unsigned long flag, struct inode *inode) 595 { 596 set_bit(flag, &OVL_I(inode)->flags); 597 } 598 599 void ovl_clear_flag(unsigned long flag, struct inode *inode) 600 { 601 clear_bit(flag, &OVL_I(inode)->flags); 602 } 603 604 bool ovl_test_flag(unsigned long flag, struct inode *inode) 605 { 606 return test_bit(flag, &OVL_I(inode)->flags); 607 } 608 609 /** 610 * Caller must hold a reference to inode to prevent it from being freed while 611 * it is marked inuse. 612 */ 613 bool ovl_inuse_trylock(struct dentry *dentry) 614 { 615 struct inode *inode = d_inode(dentry); 616 bool locked = false; 617 618 spin_lock(&inode->i_lock); 619 if (!(inode->i_state & I_OVL_INUSE)) { 620 inode->i_state |= I_OVL_INUSE; 621 locked = true; 622 } 623 spin_unlock(&inode->i_lock); 624 625 return locked; 626 } 627 628 void ovl_inuse_unlock(struct dentry *dentry) 629 { 630 if (dentry) { 631 struct inode *inode = d_inode(dentry); 632 633 spin_lock(&inode->i_lock); 634 WARN_ON(!(inode->i_state & I_OVL_INUSE)); 635 inode->i_state &= ~I_OVL_INUSE; 636 spin_unlock(&inode->i_lock); 637 } 638 } 639 640 bool ovl_is_inuse(struct dentry *dentry) 641 { 642 struct inode *inode = d_inode(dentry); 643 bool inuse; 644 645 spin_lock(&inode->i_lock); 646 inuse = (inode->i_state & I_OVL_INUSE); 647 spin_unlock(&inode->i_lock); 648 649 return inuse; 650 } 651 652 /* 653 * Does this overlay dentry need to be indexed on copy up? 654 */ 655 bool ovl_need_index(struct dentry *dentry) 656 { 657 struct dentry *lower = ovl_dentry_lower(dentry); 658 659 if (!lower || !ovl_indexdir(dentry->d_sb)) 660 return false; 661 662 /* Index all files for NFS export and consistency verification */ 663 if (ovl_index_all(dentry->d_sb)) 664 return true; 665 666 /* Index only lower hardlinks on copy up */ 667 if (!d_is_dir(lower) && d_inode(lower)->i_nlink > 1) 668 return true; 669 670 return false; 671 } 672 673 /* Caller must hold OVL_I(inode)->lock */ 674 static void ovl_cleanup_index(struct dentry *dentry) 675 { 676 struct dentry *indexdir = ovl_indexdir(dentry->d_sb); 677 struct inode *dir = indexdir->d_inode; 678 struct dentry *lowerdentry = ovl_dentry_lower(dentry); 679 struct dentry *upperdentry = ovl_dentry_upper(dentry); 680 struct dentry *index = NULL; 681 struct inode *inode; 682 struct qstr name = { }; 683 int err; 684 685 err = ovl_get_index_name(lowerdentry, &name); 686 if (err) 687 goto fail; 688 689 inode = d_inode(upperdentry); 690 if (!S_ISDIR(inode->i_mode) && inode->i_nlink != 1) { 691 pr_warn_ratelimited("cleanup linked index (%pd2, ino=%lu, nlink=%u)\n", 692 upperdentry, inode->i_ino, inode->i_nlink); 693 /* 694 * We either have a bug with persistent union nlink or a lower 695 * hardlink was added while overlay is mounted. Adding a lower 696 * hardlink and then unlinking all overlay hardlinks would drop 697 * overlay nlink to zero before all upper inodes are unlinked. 698 * As a safety measure, when that situation is detected, set 699 * the overlay nlink to the index inode nlink minus one for the 700 * index entry itself. 701 */ 702 set_nlink(d_inode(dentry), inode->i_nlink - 1); 703 ovl_set_nlink_upper(dentry); 704 goto out; 705 } 706 707 inode_lock_nested(dir, I_MUTEX_PARENT); 708 index = lookup_one_len(name.name, indexdir, name.len); 709 err = PTR_ERR(index); 710 if (IS_ERR(index)) { 711 index = NULL; 712 } else if (ovl_index_all(dentry->d_sb)) { 713 /* Whiteout orphan index to block future open by handle */ 714 err = ovl_cleanup_and_whiteout(indexdir, dir, index); 715 } else { 716 /* Cleanup orphan index entries */ 717 err = ovl_cleanup(dir, index); 718 } 719 720 inode_unlock(dir); 721 if (err) 722 goto fail; 723 724 out: 725 kfree(name.name); 726 dput(index); 727 return; 728 729 fail: 730 pr_err("cleanup index of '%pd2' failed (%i)\n", dentry, err); 731 goto out; 732 } 733 734 /* 735 * Operations that change overlay inode and upper inode nlink need to be 736 * synchronized with copy up for persistent nlink accounting. 737 */ 738 int ovl_nlink_start(struct dentry *dentry) 739 { 740 struct inode *inode = d_inode(dentry); 741 const struct cred *old_cred; 742 int err; 743 744 if (WARN_ON(!inode)) 745 return -ENOENT; 746 747 /* 748 * With inodes index is enabled, we store the union overlay nlink 749 * in an xattr on the index inode. When whiting out an indexed lower, 750 * we need to decrement the overlay persistent nlink, but before the 751 * first copy up, we have no upper index inode to store the xattr. 752 * 753 * As a workaround, before whiteout/rename over an indexed lower, 754 * copy up to create the upper index. Creating the upper index will 755 * initialize the overlay nlink, so it could be dropped if unlink 756 * or rename succeeds. 757 * 758 * TODO: implement metadata only index copy up when called with 759 * ovl_copy_up_flags(dentry, O_PATH). 760 */ 761 if (ovl_need_index(dentry) && !ovl_dentry_has_upper_alias(dentry)) { 762 err = ovl_copy_up(dentry); 763 if (err) 764 return err; 765 } 766 767 err = ovl_inode_lock(inode); 768 if (err) 769 return err; 770 771 if (d_is_dir(dentry) || !ovl_test_flag(OVL_INDEX, inode)) 772 goto out; 773 774 old_cred = ovl_override_creds(dentry->d_sb); 775 /* 776 * The overlay inode nlink should be incremented/decremented IFF the 777 * upper operation succeeds, along with nlink change of upper inode. 778 * Therefore, before link/unlink/rename, we store the union nlink 779 * value relative to the upper inode nlink in an upper inode xattr. 780 */ 781 err = ovl_set_nlink_upper(dentry); 782 revert_creds(old_cred); 783 784 out: 785 if (err) 786 ovl_inode_unlock(inode); 787 788 return err; 789 } 790 791 void ovl_nlink_end(struct dentry *dentry) 792 { 793 struct inode *inode = d_inode(dentry); 794 795 if (ovl_test_flag(OVL_INDEX, inode) && inode->i_nlink == 0) { 796 const struct cred *old_cred; 797 798 old_cred = ovl_override_creds(dentry->d_sb); 799 ovl_cleanup_index(dentry); 800 revert_creds(old_cred); 801 } 802 803 ovl_inode_unlock(inode); 804 } 805 806 int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir) 807 { 808 /* Workdir should not be the same as upperdir */ 809 if (workdir == upperdir) 810 goto err; 811 812 /* Workdir should not be subdir of upperdir and vice versa */ 813 if (lock_rename(workdir, upperdir) != NULL) 814 goto err_unlock; 815 816 return 0; 817 818 err_unlock: 819 unlock_rename(workdir, upperdir); 820 err: 821 pr_err("failed to lock workdir+upperdir\n"); 822 return -EIO; 823 } 824 825 /* err < 0, 0 if no metacopy xattr, 1 if metacopy xattr found */ 826 int ovl_check_metacopy_xattr(struct dentry *dentry) 827 { 828 int res; 829 830 /* Only regular files can have metacopy xattr */ 831 if (!S_ISREG(d_inode(dentry)->i_mode)) 832 return 0; 833 834 res = vfs_getxattr(dentry, OVL_XATTR_METACOPY, NULL, 0); 835 if (res < 0) { 836 if (res == -ENODATA || res == -EOPNOTSUPP) 837 return 0; 838 goto out; 839 } 840 841 return 1; 842 out: 843 pr_warn_ratelimited("failed to get metacopy (%i)\n", res); 844 return res; 845 } 846 847 bool ovl_is_metacopy_dentry(struct dentry *dentry) 848 { 849 struct ovl_entry *oe = dentry->d_fsdata; 850 851 if (!d_is_reg(dentry)) 852 return false; 853 854 if (ovl_dentry_upper(dentry)) { 855 if (!ovl_has_upperdata(d_inode(dentry))) 856 return true; 857 return false; 858 } 859 860 return (oe->numlower > 1); 861 } 862 863 ssize_t ovl_getxattr(struct dentry *dentry, char *name, char **value, 864 size_t padding) 865 { 866 ssize_t res; 867 char *buf = NULL; 868 869 res = vfs_getxattr(dentry, name, NULL, 0); 870 if (res < 0) { 871 if (res == -ENODATA || res == -EOPNOTSUPP) 872 return -ENODATA; 873 goto fail; 874 } 875 876 if (res != 0) { 877 buf = kzalloc(res + padding, GFP_KERNEL); 878 if (!buf) 879 return -ENOMEM; 880 881 res = vfs_getxattr(dentry, name, buf, res); 882 if (res < 0) 883 goto fail; 884 } 885 *value = buf; 886 887 return res; 888 889 fail: 890 pr_warn_ratelimited("failed to get xattr %s: err=%zi)\n", 891 name, res); 892 kfree(buf); 893 return res; 894 } 895 896 char *ovl_get_redirect_xattr(struct dentry *dentry, int padding) 897 { 898 int res; 899 char *s, *next, *buf = NULL; 900 901 res = ovl_getxattr(dentry, OVL_XATTR_REDIRECT, &buf, padding + 1); 902 if (res == -ENODATA) 903 return NULL; 904 if (res < 0) 905 return ERR_PTR(res); 906 if (res == 0) 907 goto invalid; 908 909 if (buf[0] == '/') { 910 for (s = buf; *s++ == '/'; s = next) { 911 next = strchrnul(s, '/'); 912 if (s == next) 913 goto invalid; 914 } 915 } else { 916 if (strchr(buf, '/') != NULL) 917 goto invalid; 918 } 919 920 return buf; 921 invalid: 922 pr_warn_ratelimited("invalid redirect (%s)\n", buf); 923 res = -EINVAL; 924 kfree(buf); 925 return ERR_PTR(res); 926 } 927