1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * 4 * Copyright (C) 2011 Novell Inc. 5 */ 6 7 #include <uapi/linux/magic.h> 8 #include <linux/fs.h> 9 #include <linux/namei.h> 10 #include <linux/xattr.h> 11 #include <linux/mount.h> 12 #include <linux/parser.h> 13 #include <linux/module.h> 14 #include <linux/statfs.h> 15 #include <linux/seq_file.h> 16 #include <linux/posix_acl_xattr.h> 17 #include <linux/exportfs.h> 18 #include <linux/file.h> 19 #include "overlayfs.h" 20 21 MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>"); 22 MODULE_DESCRIPTION("Overlay filesystem"); 23 MODULE_LICENSE("GPL"); 24 25 26 struct ovl_dir_cache; 27 28 #define OVL_MAX_STACK 500 29 30 static bool ovl_redirect_dir_def = IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_DIR); 31 module_param_named(redirect_dir, ovl_redirect_dir_def, bool, 0644); 32 MODULE_PARM_DESC(redirect_dir, 33 "Default to on or off for the redirect_dir feature"); 34 35 static bool ovl_redirect_always_follow = 36 IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_ALWAYS_FOLLOW); 37 module_param_named(redirect_always_follow, ovl_redirect_always_follow, 38 bool, 0644); 39 MODULE_PARM_DESC(redirect_always_follow, 40 "Follow redirects even if redirect_dir feature is turned off"); 41 42 static bool ovl_index_def = IS_ENABLED(CONFIG_OVERLAY_FS_INDEX); 43 module_param_named(index, ovl_index_def, bool, 0644); 44 MODULE_PARM_DESC(index, 45 "Default to on or off for the inodes index feature"); 46 47 static bool ovl_nfs_export_def = IS_ENABLED(CONFIG_OVERLAY_FS_NFS_EXPORT); 48 module_param_named(nfs_export, ovl_nfs_export_def, bool, 0644); 49 MODULE_PARM_DESC(nfs_export, 50 "Default to on or off for the NFS export feature"); 51 52 static bool ovl_xino_auto_def = IS_ENABLED(CONFIG_OVERLAY_FS_XINO_AUTO); 53 module_param_named(xino_auto, ovl_xino_auto_def, bool, 0644); 54 MODULE_PARM_DESC(xino_auto, 55 "Auto enable xino feature"); 56 57 static void ovl_entry_stack_free(struct ovl_entry *oe) 58 { 59 unsigned int i; 60 61 for (i = 0; i < oe->numlower; i++) 62 dput(oe->lowerstack[i].dentry); 63 } 64 65 static bool ovl_metacopy_def = IS_ENABLED(CONFIG_OVERLAY_FS_METACOPY); 66 module_param_named(metacopy, ovl_metacopy_def, bool, 0644); 67 MODULE_PARM_DESC(metacopy, 68 "Default to on or off for the metadata only copy up feature"); 69 70 static void ovl_dentry_release(struct dentry *dentry) 71 { 72 struct ovl_entry *oe = dentry->d_fsdata; 73 74 if (oe) { 75 ovl_entry_stack_free(oe); 76 kfree_rcu(oe, rcu); 77 } 78 } 79 80 static struct dentry *ovl_d_real(struct dentry *dentry, 81 const struct inode *inode) 82 { 83 struct dentry *real = NULL, *lower; 84 85 /* It's an overlay file */ 86 if (inode && d_inode(dentry) == inode) 87 return dentry; 88 89 if (!d_is_reg(dentry)) { 90 if (!inode || inode == d_inode(dentry)) 91 return dentry; 92 goto bug; 93 } 94 95 real = ovl_dentry_upper(dentry); 96 if (real && (inode == d_inode(real))) 97 return real; 98 99 if (real && !inode && ovl_has_upperdata(d_inode(dentry))) 100 return real; 101 102 lower = ovl_dentry_lowerdata(dentry); 103 if (!lower) 104 goto bug; 105 real = lower; 106 107 /* Handle recursion */ 108 real = d_real(real, inode); 109 110 if (!inode || inode == d_inode(real)) 111 return real; 112 bug: 113 WARN(1, "%s(%pd4, %s:%lu): real dentry (%p/%lu) not found\n", 114 __func__, dentry, inode ? inode->i_sb->s_id : "NULL", 115 inode ? inode->i_ino : 0, real, 116 real && d_inode(real) ? d_inode(real)->i_ino : 0); 117 return dentry; 118 } 119 120 static int ovl_revalidate_real(struct dentry *d, unsigned int flags, bool weak) 121 { 122 int ret = 1; 123 124 if (weak) { 125 if (d->d_flags & DCACHE_OP_WEAK_REVALIDATE) 126 ret = d->d_op->d_weak_revalidate(d, flags); 127 } else if (d->d_flags & DCACHE_OP_REVALIDATE) { 128 ret = d->d_op->d_revalidate(d, flags); 129 if (!ret) { 130 if (!(flags & LOOKUP_RCU)) 131 d_invalidate(d); 132 ret = -ESTALE; 133 } 134 } 135 return ret; 136 } 137 138 static int ovl_dentry_revalidate_common(struct dentry *dentry, 139 unsigned int flags, bool weak) 140 { 141 struct ovl_entry *oe = dentry->d_fsdata; 142 struct inode *inode = d_inode_rcu(dentry); 143 struct dentry *upper; 144 unsigned int i; 145 int ret = 1; 146 147 /* Careful in RCU mode */ 148 if (!inode) 149 return -ECHILD; 150 151 upper = ovl_i_dentry_upper(inode); 152 if (upper) 153 ret = ovl_revalidate_real(upper, flags, weak); 154 155 for (i = 0; ret > 0 && i < oe->numlower; i++) { 156 ret = ovl_revalidate_real(oe->lowerstack[i].dentry, flags, 157 weak); 158 } 159 return ret; 160 } 161 162 static int ovl_dentry_revalidate(struct dentry *dentry, unsigned int flags) 163 { 164 return ovl_dentry_revalidate_common(dentry, flags, false); 165 } 166 167 static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags) 168 { 169 return ovl_dentry_revalidate_common(dentry, flags, true); 170 } 171 172 static const struct dentry_operations ovl_dentry_operations = { 173 .d_release = ovl_dentry_release, 174 .d_real = ovl_d_real, 175 .d_revalidate = ovl_dentry_revalidate, 176 .d_weak_revalidate = ovl_dentry_weak_revalidate, 177 }; 178 179 static struct kmem_cache *ovl_inode_cachep; 180 181 static struct inode *ovl_alloc_inode(struct super_block *sb) 182 { 183 struct ovl_inode *oi = alloc_inode_sb(sb, ovl_inode_cachep, GFP_KERNEL); 184 185 if (!oi) 186 return NULL; 187 188 oi->cache = NULL; 189 oi->redirect = NULL; 190 oi->version = 0; 191 oi->flags = 0; 192 oi->__upperdentry = NULL; 193 oi->lowerpath.dentry = NULL; 194 oi->lowerpath.layer = NULL; 195 oi->lowerdata = NULL; 196 mutex_init(&oi->lock); 197 198 return &oi->vfs_inode; 199 } 200 201 static void ovl_free_inode(struct inode *inode) 202 { 203 struct ovl_inode *oi = OVL_I(inode); 204 205 kfree(oi->redirect); 206 mutex_destroy(&oi->lock); 207 kmem_cache_free(ovl_inode_cachep, oi); 208 } 209 210 static void ovl_destroy_inode(struct inode *inode) 211 { 212 struct ovl_inode *oi = OVL_I(inode); 213 214 dput(oi->__upperdentry); 215 dput(oi->lowerpath.dentry); 216 if (S_ISDIR(inode->i_mode)) 217 ovl_dir_cache_free(inode); 218 else 219 iput(oi->lowerdata); 220 } 221 222 static void ovl_free_fs(struct ovl_fs *ofs) 223 { 224 struct vfsmount **mounts; 225 unsigned i; 226 227 iput(ofs->workbasedir_trap); 228 iput(ofs->indexdir_trap); 229 iput(ofs->workdir_trap); 230 dput(ofs->whiteout); 231 dput(ofs->indexdir); 232 dput(ofs->workdir); 233 if (ofs->workdir_locked) 234 ovl_inuse_unlock(ofs->workbasedir); 235 dput(ofs->workbasedir); 236 if (ofs->upperdir_locked) 237 ovl_inuse_unlock(ovl_upper_mnt(ofs)->mnt_root); 238 239 /* Hack! Reuse ofs->layers as a vfsmount array before freeing it */ 240 mounts = (struct vfsmount **) ofs->layers; 241 for (i = 0; i < ofs->numlayer; i++) { 242 iput(ofs->layers[i].trap); 243 mounts[i] = ofs->layers[i].mnt; 244 } 245 kern_unmount_array(mounts, ofs->numlayer); 246 kfree(ofs->layers); 247 for (i = 0; i < ofs->numfs; i++) 248 free_anon_bdev(ofs->fs[i].pseudo_dev); 249 kfree(ofs->fs); 250 251 kfree(ofs->config.lowerdir); 252 kfree(ofs->config.upperdir); 253 kfree(ofs->config.workdir); 254 kfree(ofs->config.redirect_mode); 255 if (ofs->creator_cred) 256 put_cred(ofs->creator_cred); 257 kfree(ofs); 258 } 259 260 static void ovl_put_super(struct super_block *sb) 261 { 262 struct ovl_fs *ofs = sb->s_fs_info; 263 264 ovl_free_fs(ofs); 265 } 266 267 /* Sync real dirty inodes in upper filesystem (if it exists) */ 268 static int ovl_sync_fs(struct super_block *sb, int wait) 269 { 270 struct ovl_fs *ofs = sb->s_fs_info; 271 struct super_block *upper_sb; 272 int ret; 273 274 ret = ovl_sync_status(ofs); 275 /* 276 * We have to always set the err, because the return value isn't 277 * checked in syncfs, and instead indirectly return an error via 278 * the sb's writeback errseq, which VFS inspects after this call. 279 */ 280 if (ret < 0) { 281 errseq_set(&sb->s_wb_err, -EIO); 282 return -EIO; 283 } 284 285 if (!ret) 286 return ret; 287 288 /* 289 * Not called for sync(2) call or an emergency sync (SB_I_SKIP_SYNC). 290 * All the super blocks will be iterated, including upper_sb. 291 * 292 * If this is a syncfs(2) call, then we do need to call 293 * sync_filesystem() on upper_sb, but enough if we do it when being 294 * called with wait == 1. 295 */ 296 if (!wait) 297 return 0; 298 299 upper_sb = ovl_upper_mnt(ofs)->mnt_sb; 300 301 down_read(&upper_sb->s_umount); 302 ret = sync_filesystem(upper_sb); 303 up_read(&upper_sb->s_umount); 304 305 return ret; 306 } 307 308 /** 309 * ovl_statfs 310 * @dentry: The dentry to query 311 * @buf: The struct kstatfs to fill in with stats 312 * 313 * Get the filesystem statistics. As writes always target the upper layer 314 * filesystem pass the statfs to the upper filesystem (if it exists) 315 */ 316 static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf) 317 { 318 struct ovl_fs *ofs = dentry->d_sb->s_fs_info; 319 struct dentry *root_dentry = dentry->d_sb->s_root; 320 struct path path; 321 int err; 322 323 ovl_path_real(root_dentry, &path); 324 325 err = vfs_statfs(&path, buf); 326 if (!err) { 327 buf->f_namelen = ofs->namelen; 328 buf->f_type = OVERLAYFS_SUPER_MAGIC; 329 } 330 331 return err; 332 } 333 334 /* Will this overlay be forced to mount/remount ro? */ 335 static bool ovl_force_readonly(struct ovl_fs *ofs) 336 { 337 return (!ovl_upper_mnt(ofs) || !ofs->workdir); 338 } 339 340 static const char *ovl_redirect_mode_def(void) 341 { 342 return ovl_redirect_dir_def ? "on" : "off"; 343 } 344 345 static const char * const ovl_xino_str[] = { 346 "off", 347 "auto", 348 "on", 349 }; 350 351 static inline int ovl_xino_def(void) 352 { 353 return ovl_xino_auto_def ? OVL_XINO_AUTO : OVL_XINO_OFF; 354 } 355 356 /** 357 * ovl_show_options 358 * @m: the seq_file handle 359 * @dentry: The dentry to query 360 * 361 * Prints the mount options for a given superblock. 362 * Returns zero; does not fail. 363 */ 364 static int ovl_show_options(struct seq_file *m, struct dentry *dentry) 365 { 366 struct super_block *sb = dentry->d_sb; 367 struct ovl_fs *ofs = sb->s_fs_info; 368 369 seq_show_option(m, "lowerdir", ofs->config.lowerdir); 370 if (ofs->config.upperdir) { 371 seq_show_option(m, "upperdir", ofs->config.upperdir); 372 seq_show_option(m, "workdir", ofs->config.workdir); 373 } 374 if (ofs->config.default_permissions) 375 seq_puts(m, ",default_permissions"); 376 if (strcmp(ofs->config.redirect_mode, ovl_redirect_mode_def()) != 0) 377 seq_printf(m, ",redirect_dir=%s", ofs->config.redirect_mode); 378 if (ofs->config.index != ovl_index_def) 379 seq_printf(m, ",index=%s", ofs->config.index ? "on" : "off"); 380 if (!ofs->config.uuid) 381 seq_puts(m, ",uuid=off"); 382 if (ofs->config.nfs_export != ovl_nfs_export_def) 383 seq_printf(m, ",nfs_export=%s", ofs->config.nfs_export ? 384 "on" : "off"); 385 if (ofs->config.xino != ovl_xino_def() && !ovl_same_fs(sb)) 386 seq_printf(m, ",xino=%s", ovl_xino_str[ofs->config.xino]); 387 if (ofs->config.metacopy != ovl_metacopy_def) 388 seq_printf(m, ",metacopy=%s", 389 ofs->config.metacopy ? "on" : "off"); 390 if (ofs->config.ovl_volatile) 391 seq_puts(m, ",volatile"); 392 if (ofs->config.userxattr) 393 seq_puts(m, ",userxattr"); 394 return 0; 395 } 396 397 static int ovl_remount(struct super_block *sb, int *flags, char *data) 398 { 399 struct ovl_fs *ofs = sb->s_fs_info; 400 struct super_block *upper_sb; 401 int ret = 0; 402 403 if (!(*flags & SB_RDONLY) && ovl_force_readonly(ofs)) 404 return -EROFS; 405 406 if (*flags & SB_RDONLY && !sb_rdonly(sb)) { 407 upper_sb = ovl_upper_mnt(ofs)->mnt_sb; 408 if (ovl_should_sync(ofs)) { 409 down_read(&upper_sb->s_umount); 410 ret = sync_filesystem(upper_sb); 411 up_read(&upper_sb->s_umount); 412 } 413 } 414 415 return ret; 416 } 417 418 static const struct super_operations ovl_super_operations = { 419 .alloc_inode = ovl_alloc_inode, 420 .free_inode = ovl_free_inode, 421 .destroy_inode = ovl_destroy_inode, 422 .drop_inode = generic_delete_inode, 423 .put_super = ovl_put_super, 424 .sync_fs = ovl_sync_fs, 425 .statfs = ovl_statfs, 426 .show_options = ovl_show_options, 427 .remount_fs = ovl_remount, 428 }; 429 430 enum { 431 OPT_LOWERDIR, 432 OPT_UPPERDIR, 433 OPT_WORKDIR, 434 OPT_DEFAULT_PERMISSIONS, 435 OPT_REDIRECT_DIR, 436 OPT_INDEX_ON, 437 OPT_INDEX_OFF, 438 OPT_UUID_ON, 439 OPT_UUID_OFF, 440 OPT_NFS_EXPORT_ON, 441 OPT_USERXATTR, 442 OPT_NFS_EXPORT_OFF, 443 OPT_XINO_ON, 444 OPT_XINO_OFF, 445 OPT_XINO_AUTO, 446 OPT_METACOPY_ON, 447 OPT_METACOPY_OFF, 448 OPT_VOLATILE, 449 OPT_ERR, 450 }; 451 452 static const match_table_t ovl_tokens = { 453 {OPT_LOWERDIR, "lowerdir=%s"}, 454 {OPT_UPPERDIR, "upperdir=%s"}, 455 {OPT_WORKDIR, "workdir=%s"}, 456 {OPT_DEFAULT_PERMISSIONS, "default_permissions"}, 457 {OPT_REDIRECT_DIR, "redirect_dir=%s"}, 458 {OPT_INDEX_ON, "index=on"}, 459 {OPT_INDEX_OFF, "index=off"}, 460 {OPT_USERXATTR, "userxattr"}, 461 {OPT_UUID_ON, "uuid=on"}, 462 {OPT_UUID_OFF, "uuid=off"}, 463 {OPT_NFS_EXPORT_ON, "nfs_export=on"}, 464 {OPT_NFS_EXPORT_OFF, "nfs_export=off"}, 465 {OPT_XINO_ON, "xino=on"}, 466 {OPT_XINO_OFF, "xino=off"}, 467 {OPT_XINO_AUTO, "xino=auto"}, 468 {OPT_METACOPY_ON, "metacopy=on"}, 469 {OPT_METACOPY_OFF, "metacopy=off"}, 470 {OPT_VOLATILE, "volatile"}, 471 {OPT_ERR, NULL} 472 }; 473 474 static char *ovl_next_opt(char **s) 475 { 476 char *sbegin = *s; 477 char *p; 478 479 if (sbegin == NULL) 480 return NULL; 481 482 for (p = sbegin; *p; p++) { 483 if (*p == '\\') { 484 p++; 485 if (!*p) 486 break; 487 } else if (*p == ',') { 488 *p = '\0'; 489 *s = p + 1; 490 return sbegin; 491 } 492 } 493 *s = NULL; 494 return sbegin; 495 } 496 497 static int ovl_parse_redirect_mode(struct ovl_config *config, const char *mode) 498 { 499 if (strcmp(mode, "on") == 0) { 500 config->redirect_dir = true; 501 /* 502 * Does not make sense to have redirect creation without 503 * redirect following. 504 */ 505 config->redirect_follow = true; 506 } else if (strcmp(mode, "follow") == 0) { 507 config->redirect_follow = true; 508 } else if (strcmp(mode, "off") == 0) { 509 if (ovl_redirect_always_follow) 510 config->redirect_follow = true; 511 } else if (strcmp(mode, "nofollow") != 0) { 512 pr_err("bad mount option \"redirect_dir=%s\"\n", 513 mode); 514 return -EINVAL; 515 } 516 517 return 0; 518 } 519 520 static int ovl_parse_opt(char *opt, struct ovl_config *config) 521 { 522 char *p; 523 int err; 524 bool metacopy_opt = false, redirect_opt = false; 525 bool nfs_export_opt = false, index_opt = false; 526 527 config->redirect_mode = kstrdup(ovl_redirect_mode_def(), GFP_KERNEL); 528 if (!config->redirect_mode) 529 return -ENOMEM; 530 531 while ((p = ovl_next_opt(&opt)) != NULL) { 532 int token; 533 substring_t args[MAX_OPT_ARGS]; 534 535 if (!*p) 536 continue; 537 538 token = match_token(p, ovl_tokens, args); 539 switch (token) { 540 case OPT_UPPERDIR: 541 kfree(config->upperdir); 542 config->upperdir = match_strdup(&args[0]); 543 if (!config->upperdir) 544 return -ENOMEM; 545 break; 546 547 case OPT_LOWERDIR: 548 kfree(config->lowerdir); 549 config->lowerdir = match_strdup(&args[0]); 550 if (!config->lowerdir) 551 return -ENOMEM; 552 break; 553 554 case OPT_WORKDIR: 555 kfree(config->workdir); 556 config->workdir = match_strdup(&args[0]); 557 if (!config->workdir) 558 return -ENOMEM; 559 break; 560 561 case OPT_DEFAULT_PERMISSIONS: 562 config->default_permissions = true; 563 break; 564 565 case OPT_REDIRECT_DIR: 566 kfree(config->redirect_mode); 567 config->redirect_mode = match_strdup(&args[0]); 568 if (!config->redirect_mode) 569 return -ENOMEM; 570 redirect_opt = true; 571 break; 572 573 case OPT_INDEX_ON: 574 config->index = true; 575 index_opt = true; 576 break; 577 578 case OPT_INDEX_OFF: 579 config->index = false; 580 index_opt = true; 581 break; 582 583 case OPT_UUID_ON: 584 config->uuid = true; 585 break; 586 587 case OPT_UUID_OFF: 588 config->uuid = false; 589 break; 590 591 case OPT_NFS_EXPORT_ON: 592 config->nfs_export = true; 593 nfs_export_opt = true; 594 break; 595 596 case OPT_NFS_EXPORT_OFF: 597 config->nfs_export = false; 598 nfs_export_opt = true; 599 break; 600 601 case OPT_XINO_ON: 602 config->xino = OVL_XINO_ON; 603 break; 604 605 case OPT_XINO_OFF: 606 config->xino = OVL_XINO_OFF; 607 break; 608 609 case OPT_XINO_AUTO: 610 config->xino = OVL_XINO_AUTO; 611 break; 612 613 case OPT_METACOPY_ON: 614 config->metacopy = true; 615 metacopy_opt = true; 616 break; 617 618 case OPT_METACOPY_OFF: 619 config->metacopy = false; 620 metacopy_opt = true; 621 break; 622 623 case OPT_VOLATILE: 624 config->ovl_volatile = true; 625 break; 626 627 case OPT_USERXATTR: 628 config->userxattr = true; 629 break; 630 631 default: 632 pr_err("unrecognized mount option \"%s\" or missing value\n", 633 p); 634 return -EINVAL; 635 } 636 } 637 638 /* Workdir/index are useless in non-upper mount */ 639 if (!config->upperdir) { 640 if (config->workdir) { 641 pr_info("option \"workdir=%s\" is useless in a non-upper mount, ignore\n", 642 config->workdir); 643 kfree(config->workdir); 644 config->workdir = NULL; 645 } 646 if (config->index && index_opt) { 647 pr_info("option \"index=on\" is useless in a non-upper mount, ignore\n"); 648 index_opt = false; 649 } 650 config->index = false; 651 } 652 653 if (!config->upperdir && config->ovl_volatile) { 654 pr_info("option \"volatile\" is meaningless in a non-upper mount, ignoring it.\n"); 655 config->ovl_volatile = false; 656 } 657 658 err = ovl_parse_redirect_mode(config, config->redirect_mode); 659 if (err) 660 return err; 661 662 /* 663 * This is to make the logic below simpler. It doesn't make any other 664 * difference, since config->redirect_dir is only used for upper. 665 */ 666 if (!config->upperdir && config->redirect_follow) 667 config->redirect_dir = true; 668 669 /* Resolve metacopy -> redirect_dir dependency */ 670 if (config->metacopy && !config->redirect_dir) { 671 if (metacopy_opt && redirect_opt) { 672 pr_err("conflicting options: metacopy=on,redirect_dir=%s\n", 673 config->redirect_mode); 674 return -EINVAL; 675 } 676 if (redirect_opt) { 677 /* 678 * There was an explicit redirect_dir=... that resulted 679 * in this conflict. 680 */ 681 pr_info("disabling metacopy due to redirect_dir=%s\n", 682 config->redirect_mode); 683 config->metacopy = false; 684 } else { 685 /* Automatically enable redirect otherwise. */ 686 config->redirect_follow = config->redirect_dir = true; 687 } 688 } 689 690 /* Resolve nfs_export -> index dependency */ 691 if (config->nfs_export && !config->index) { 692 if (!config->upperdir && config->redirect_follow) { 693 pr_info("NFS export requires \"redirect_dir=nofollow\" on non-upper mount, falling back to nfs_export=off.\n"); 694 config->nfs_export = false; 695 } else if (nfs_export_opt && index_opt) { 696 pr_err("conflicting options: nfs_export=on,index=off\n"); 697 return -EINVAL; 698 } else if (index_opt) { 699 /* 700 * There was an explicit index=off that resulted 701 * in this conflict. 702 */ 703 pr_info("disabling nfs_export due to index=off\n"); 704 config->nfs_export = false; 705 } else { 706 /* Automatically enable index otherwise. */ 707 config->index = true; 708 } 709 } 710 711 /* Resolve nfs_export -> !metacopy dependency */ 712 if (config->nfs_export && config->metacopy) { 713 if (nfs_export_opt && metacopy_opt) { 714 pr_err("conflicting options: nfs_export=on,metacopy=on\n"); 715 return -EINVAL; 716 } 717 if (metacopy_opt) { 718 /* 719 * There was an explicit metacopy=on that resulted 720 * in this conflict. 721 */ 722 pr_info("disabling nfs_export due to metacopy=on\n"); 723 config->nfs_export = false; 724 } else { 725 /* 726 * There was an explicit nfs_export=on that resulted 727 * in this conflict. 728 */ 729 pr_info("disabling metacopy due to nfs_export=on\n"); 730 config->metacopy = false; 731 } 732 } 733 734 735 /* Resolve userxattr -> !redirect && !metacopy dependency */ 736 if (config->userxattr) { 737 if (config->redirect_follow && redirect_opt) { 738 pr_err("conflicting options: userxattr,redirect_dir=%s\n", 739 config->redirect_mode); 740 return -EINVAL; 741 } 742 if (config->metacopy && metacopy_opt) { 743 pr_err("conflicting options: userxattr,metacopy=on\n"); 744 return -EINVAL; 745 } 746 /* 747 * Silently disable default setting of redirect and metacopy. 748 * This shall be the default in the future as well: these 749 * options must be explicitly enabled if used together with 750 * userxattr. 751 */ 752 config->redirect_dir = config->redirect_follow = false; 753 config->metacopy = false; 754 } 755 756 return 0; 757 } 758 759 #define OVL_WORKDIR_NAME "work" 760 #define OVL_INDEXDIR_NAME "index" 761 762 static struct dentry *ovl_workdir_create(struct ovl_fs *ofs, 763 const char *name, bool persist) 764 { 765 struct inode *dir = ofs->workbasedir->d_inode; 766 struct vfsmount *mnt = ovl_upper_mnt(ofs); 767 struct dentry *work; 768 int err; 769 bool retried = false; 770 771 inode_lock_nested(dir, I_MUTEX_PARENT); 772 retry: 773 work = ovl_lookup_upper(ofs, name, ofs->workbasedir, strlen(name)); 774 775 if (!IS_ERR(work)) { 776 struct iattr attr = { 777 .ia_valid = ATTR_MODE, 778 .ia_mode = S_IFDIR | 0, 779 }; 780 781 if (work->d_inode) { 782 err = -EEXIST; 783 if (retried) 784 goto out_dput; 785 786 if (persist) 787 goto out_unlock; 788 789 retried = true; 790 err = ovl_workdir_cleanup(ofs, dir, mnt, work, 0); 791 dput(work); 792 if (err == -EINVAL) { 793 work = ERR_PTR(err); 794 goto out_unlock; 795 } 796 goto retry; 797 } 798 799 err = ovl_mkdir_real(ofs, dir, &work, attr.ia_mode); 800 if (err) 801 goto out_dput; 802 803 /* Weird filesystem returning with hashed negative (kernfs)? */ 804 err = -EINVAL; 805 if (d_really_is_negative(work)) 806 goto out_dput; 807 808 /* 809 * Try to remove POSIX ACL xattrs from workdir. We are good if: 810 * 811 * a) success (there was a POSIX ACL xattr and was removed) 812 * b) -ENODATA (there was no POSIX ACL xattr) 813 * c) -EOPNOTSUPP (POSIX ACL xattrs are not supported) 814 * 815 * There are various other error values that could effectively 816 * mean that the xattr doesn't exist (e.g. -ERANGE is returned 817 * if the xattr name is too long), but the set of filesystems 818 * allowed as upper are limited to "normal" ones, where checking 819 * for the above two errors is sufficient. 820 */ 821 err = ovl_do_remove_acl(ofs, work, XATTR_NAME_POSIX_ACL_DEFAULT); 822 if (err && err != -ENODATA && err != -EOPNOTSUPP) 823 goto out_dput; 824 825 err = ovl_do_remove_acl(ofs, work, XATTR_NAME_POSIX_ACL_ACCESS); 826 if (err && err != -ENODATA && err != -EOPNOTSUPP) 827 goto out_dput; 828 829 /* Clear any inherited mode bits */ 830 inode_lock(work->d_inode); 831 err = ovl_do_notify_change(ofs, work, &attr); 832 inode_unlock(work->d_inode); 833 if (err) 834 goto out_dput; 835 } else { 836 err = PTR_ERR(work); 837 goto out_err; 838 } 839 out_unlock: 840 inode_unlock(dir); 841 return work; 842 843 out_dput: 844 dput(work); 845 out_err: 846 pr_warn("failed to create directory %s/%s (errno: %i); mounting read-only\n", 847 ofs->config.workdir, name, -err); 848 work = NULL; 849 goto out_unlock; 850 } 851 852 static void ovl_unescape(char *s) 853 { 854 char *d = s; 855 856 for (;; s++, d++) { 857 if (*s == '\\') 858 s++; 859 *d = *s; 860 if (!*s) 861 break; 862 } 863 } 864 865 static int ovl_mount_dir_noesc(const char *name, struct path *path) 866 { 867 int err = -EINVAL; 868 869 if (!*name) { 870 pr_err("empty lowerdir\n"); 871 goto out; 872 } 873 err = kern_path(name, LOOKUP_FOLLOW, path); 874 if (err) { 875 pr_err("failed to resolve '%s': %i\n", name, err); 876 goto out; 877 } 878 err = -EINVAL; 879 if (ovl_dentry_weird(path->dentry)) { 880 pr_err("filesystem on '%s' not supported\n", name); 881 goto out_put; 882 } 883 if (!d_is_dir(path->dentry)) { 884 pr_err("'%s' not a directory\n", name); 885 goto out_put; 886 } 887 return 0; 888 889 out_put: 890 path_put_init(path); 891 out: 892 return err; 893 } 894 895 static int ovl_mount_dir(const char *name, struct path *path) 896 { 897 int err = -ENOMEM; 898 char *tmp = kstrdup(name, GFP_KERNEL); 899 900 if (tmp) { 901 ovl_unescape(tmp); 902 err = ovl_mount_dir_noesc(tmp, path); 903 904 if (!err && path->dentry->d_flags & DCACHE_OP_REAL) { 905 pr_err("filesystem on '%s' not supported as upperdir\n", 906 tmp); 907 path_put_init(path); 908 err = -EINVAL; 909 } 910 kfree(tmp); 911 } 912 return err; 913 } 914 915 static int ovl_check_namelen(const struct path *path, struct ovl_fs *ofs, 916 const char *name) 917 { 918 struct kstatfs statfs; 919 int err = vfs_statfs(path, &statfs); 920 921 if (err) 922 pr_err("statfs failed on '%s'\n", name); 923 else 924 ofs->namelen = max(ofs->namelen, statfs.f_namelen); 925 926 return err; 927 } 928 929 static int ovl_lower_dir(const char *name, struct path *path, 930 struct ovl_fs *ofs, int *stack_depth) 931 { 932 int fh_type; 933 int err; 934 935 err = ovl_mount_dir_noesc(name, path); 936 if (err) 937 return err; 938 939 err = ovl_check_namelen(path, ofs, name); 940 if (err) 941 return err; 942 943 *stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth); 944 945 /* 946 * The inodes index feature and NFS export need to encode and decode 947 * file handles, so they require that all layers support them. 948 */ 949 fh_type = ovl_can_decode_fh(path->dentry->d_sb); 950 if ((ofs->config.nfs_export || 951 (ofs->config.index && ofs->config.upperdir)) && !fh_type) { 952 ofs->config.index = false; 953 ofs->config.nfs_export = false; 954 pr_warn("fs on '%s' does not support file handles, falling back to index=off,nfs_export=off.\n", 955 name); 956 } 957 /* 958 * Decoding origin file handle is required for persistent st_ino. 959 * Without persistent st_ino, xino=auto falls back to xino=off. 960 */ 961 if (ofs->config.xino == OVL_XINO_AUTO && 962 ofs->config.upperdir && !fh_type) { 963 ofs->config.xino = OVL_XINO_OFF; 964 pr_warn("fs on '%s' does not support file handles, falling back to xino=off.\n", 965 name); 966 } 967 968 /* Check if lower fs has 32bit inode numbers */ 969 if (fh_type != FILEID_INO32_GEN) 970 ofs->xino_mode = -1; 971 972 return 0; 973 } 974 975 /* Workdir should not be subdir of upperdir and vice versa */ 976 static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir) 977 { 978 bool ok = false; 979 980 if (workdir != upperdir) { 981 ok = (lock_rename(workdir, upperdir) == NULL); 982 unlock_rename(workdir, upperdir); 983 } 984 return ok; 985 } 986 987 static unsigned int ovl_split_lowerdirs(char *str) 988 { 989 unsigned int ctr = 1; 990 char *s, *d; 991 992 for (s = d = str;; s++, d++) { 993 if (*s == '\\') { 994 s++; 995 } else if (*s == ':') { 996 *d = '\0'; 997 ctr++; 998 continue; 999 } 1000 *d = *s; 1001 if (!*s) 1002 break; 1003 } 1004 return ctr; 1005 } 1006 1007 static int ovl_own_xattr_get(const struct xattr_handler *handler, 1008 struct dentry *dentry, struct inode *inode, 1009 const char *name, void *buffer, size_t size) 1010 { 1011 return -EOPNOTSUPP; 1012 } 1013 1014 static int ovl_own_xattr_set(const struct xattr_handler *handler, 1015 struct user_namespace *mnt_userns, 1016 struct dentry *dentry, struct inode *inode, 1017 const char *name, const void *value, 1018 size_t size, int flags) 1019 { 1020 return -EOPNOTSUPP; 1021 } 1022 1023 static int ovl_other_xattr_get(const struct xattr_handler *handler, 1024 struct dentry *dentry, struct inode *inode, 1025 const char *name, void *buffer, size_t size) 1026 { 1027 return ovl_xattr_get(dentry, inode, name, buffer, size); 1028 } 1029 1030 static int ovl_other_xattr_set(const struct xattr_handler *handler, 1031 struct user_namespace *mnt_userns, 1032 struct dentry *dentry, struct inode *inode, 1033 const char *name, const void *value, 1034 size_t size, int flags) 1035 { 1036 return ovl_xattr_set(dentry, inode, name, value, size, flags); 1037 } 1038 1039 static const struct xattr_handler ovl_own_trusted_xattr_handler = { 1040 .prefix = OVL_XATTR_TRUSTED_PREFIX, 1041 .get = ovl_own_xattr_get, 1042 .set = ovl_own_xattr_set, 1043 }; 1044 1045 static const struct xattr_handler ovl_own_user_xattr_handler = { 1046 .prefix = OVL_XATTR_USER_PREFIX, 1047 .get = ovl_own_xattr_get, 1048 .set = ovl_own_xattr_set, 1049 }; 1050 1051 static const struct xattr_handler ovl_other_xattr_handler = { 1052 .prefix = "", /* catch all */ 1053 .get = ovl_other_xattr_get, 1054 .set = ovl_other_xattr_set, 1055 }; 1056 1057 static const struct xattr_handler *ovl_trusted_xattr_handlers[] = { 1058 #ifdef CONFIG_FS_POSIX_ACL 1059 &posix_acl_access_xattr_handler, 1060 &posix_acl_default_xattr_handler, 1061 #endif 1062 &ovl_own_trusted_xattr_handler, 1063 &ovl_other_xattr_handler, 1064 NULL 1065 }; 1066 1067 static const struct xattr_handler *ovl_user_xattr_handlers[] = { 1068 #ifdef CONFIG_FS_POSIX_ACL 1069 &posix_acl_access_xattr_handler, 1070 &posix_acl_default_xattr_handler, 1071 #endif 1072 &ovl_own_user_xattr_handler, 1073 &ovl_other_xattr_handler, 1074 NULL 1075 }; 1076 1077 static int ovl_setup_trap(struct super_block *sb, struct dentry *dir, 1078 struct inode **ptrap, const char *name) 1079 { 1080 struct inode *trap; 1081 int err; 1082 1083 trap = ovl_get_trap_inode(sb, dir); 1084 err = PTR_ERR_OR_ZERO(trap); 1085 if (err) { 1086 if (err == -ELOOP) 1087 pr_err("conflicting %s path\n", name); 1088 return err; 1089 } 1090 1091 *ptrap = trap; 1092 return 0; 1093 } 1094 1095 /* 1096 * Determine how we treat concurrent use of upperdir/workdir based on the 1097 * index feature. This is papering over mount leaks of container runtimes, 1098 * for example, an old overlay mount is leaked and now its upperdir is 1099 * attempted to be used as a lower layer in a new overlay mount. 1100 */ 1101 static int ovl_report_in_use(struct ovl_fs *ofs, const char *name) 1102 { 1103 if (ofs->config.index) { 1104 pr_err("%s is in-use as upperdir/workdir of another mount, mount with '-o index=off' to override exclusive upperdir protection.\n", 1105 name); 1106 return -EBUSY; 1107 } else { 1108 pr_warn("%s is in-use as upperdir/workdir of another mount, accessing files from both mounts will result in undefined behavior.\n", 1109 name); 1110 return 0; 1111 } 1112 } 1113 1114 static int ovl_get_upper(struct super_block *sb, struct ovl_fs *ofs, 1115 struct ovl_layer *upper_layer, struct path *upperpath) 1116 { 1117 struct vfsmount *upper_mnt; 1118 int err; 1119 1120 err = ovl_mount_dir(ofs->config.upperdir, upperpath); 1121 if (err) 1122 goto out; 1123 1124 /* Upperdir path should not be r/o */ 1125 if (__mnt_is_readonly(upperpath->mnt)) { 1126 pr_err("upper fs is r/o, try multi-lower layers mount\n"); 1127 err = -EINVAL; 1128 goto out; 1129 } 1130 1131 err = ovl_check_namelen(upperpath, ofs, ofs->config.upperdir); 1132 if (err) 1133 goto out; 1134 1135 err = ovl_setup_trap(sb, upperpath->dentry, &upper_layer->trap, 1136 "upperdir"); 1137 if (err) 1138 goto out; 1139 1140 upper_mnt = clone_private_mount(upperpath); 1141 err = PTR_ERR(upper_mnt); 1142 if (IS_ERR(upper_mnt)) { 1143 pr_err("failed to clone upperpath\n"); 1144 goto out; 1145 } 1146 1147 /* Don't inherit atime flags */ 1148 upper_mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME); 1149 upper_layer->mnt = upper_mnt; 1150 upper_layer->idx = 0; 1151 upper_layer->fsid = 0; 1152 1153 /* 1154 * Inherit SB_NOSEC flag from upperdir. 1155 * 1156 * This optimization changes behavior when a security related attribute 1157 * (suid/sgid/security.*) is changed on an underlying layer. This is 1158 * okay because we don't yet have guarantees in that case, but it will 1159 * need careful treatment once we want to honour changes to underlying 1160 * filesystems. 1161 */ 1162 if (upper_mnt->mnt_sb->s_flags & SB_NOSEC) 1163 sb->s_flags |= SB_NOSEC; 1164 1165 if (ovl_inuse_trylock(ovl_upper_mnt(ofs)->mnt_root)) { 1166 ofs->upperdir_locked = true; 1167 } else { 1168 err = ovl_report_in_use(ofs, "upperdir"); 1169 if (err) 1170 goto out; 1171 } 1172 1173 err = 0; 1174 out: 1175 return err; 1176 } 1177 1178 /* 1179 * Returns 1 if RENAME_WHITEOUT is supported, 0 if not supported and 1180 * negative values if error is encountered. 1181 */ 1182 static int ovl_check_rename_whiteout(struct ovl_fs *ofs) 1183 { 1184 struct dentry *workdir = ofs->workdir; 1185 struct inode *dir = d_inode(workdir); 1186 struct dentry *temp; 1187 struct dentry *dest; 1188 struct dentry *whiteout; 1189 struct name_snapshot name; 1190 int err; 1191 1192 inode_lock_nested(dir, I_MUTEX_PARENT); 1193 1194 temp = ovl_create_temp(ofs, workdir, OVL_CATTR(S_IFREG | 0)); 1195 err = PTR_ERR(temp); 1196 if (IS_ERR(temp)) 1197 goto out_unlock; 1198 1199 dest = ovl_lookup_temp(ofs, workdir); 1200 err = PTR_ERR(dest); 1201 if (IS_ERR(dest)) { 1202 dput(temp); 1203 goto out_unlock; 1204 } 1205 1206 /* Name is inline and stable - using snapshot as a copy helper */ 1207 take_dentry_name_snapshot(&name, temp); 1208 err = ovl_do_rename(ofs, dir, temp, dir, dest, RENAME_WHITEOUT); 1209 if (err) { 1210 if (err == -EINVAL) 1211 err = 0; 1212 goto cleanup_temp; 1213 } 1214 1215 whiteout = ovl_lookup_upper(ofs, name.name.name, workdir, name.name.len); 1216 err = PTR_ERR(whiteout); 1217 if (IS_ERR(whiteout)) 1218 goto cleanup_temp; 1219 1220 err = ovl_is_whiteout(whiteout); 1221 1222 /* Best effort cleanup of whiteout and temp file */ 1223 if (err) 1224 ovl_cleanup(ofs, dir, whiteout); 1225 dput(whiteout); 1226 1227 cleanup_temp: 1228 ovl_cleanup(ofs, dir, temp); 1229 release_dentry_name_snapshot(&name); 1230 dput(temp); 1231 dput(dest); 1232 1233 out_unlock: 1234 inode_unlock(dir); 1235 1236 return err; 1237 } 1238 1239 static struct dentry *ovl_lookup_or_create(struct ovl_fs *ofs, 1240 struct dentry *parent, 1241 const char *name, umode_t mode) 1242 { 1243 size_t len = strlen(name); 1244 struct dentry *child; 1245 1246 inode_lock_nested(parent->d_inode, I_MUTEX_PARENT); 1247 child = ovl_lookup_upper(ofs, name, parent, len); 1248 if (!IS_ERR(child) && !child->d_inode) 1249 child = ovl_create_real(ofs, parent->d_inode, child, 1250 OVL_CATTR(mode)); 1251 inode_unlock(parent->d_inode); 1252 dput(parent); 1253 1254 return child; 1255 } 1256 1257 /* 1258 * Creates $workdir/work/incompat/volatile/dirty file if it is not already 1259 * present. 1260 */ 1261 static int ovl_create_volatile_dirty(struct ovl_fs *ofs) 1262 { 1263 unsigned int ctr; 1264 struct dentry *d = dget(ofs->workbasedir); 1265 static const char *const volatile_path[] = { 1266 OVL_WORKDIR_NAME, "incompat", "volatile", "dirty" 1267 }; 1268 const char *const *name = volatile_path; 1269 1270 for (ctr = ARRAY_SIZE(volatile_path); ctr; ctr--, name++) { 1271 d = ovl_lookup_or_create(ofs, d, *name, ctr > 1 ? S_IFDIR : S_IFREG); 1272 if (IS_ERR(d)) 1273 return PTR_ERR(d); 1274 } 1275 dput(d); 1276 return 0; 1277 } 1278 1279 static int ovl_make_workdir(struct super_block *sb, struct ovl_fs *ofs, 1280 const struct path *workpath) 1281 { 1282 struct vfsmount *mnt = ovl_upper_mnt(ofs); 1283 struct dentry *workdir; 1284 struct file *tmpfile; 1285 bool rename_whiteout; 1286 bool d_type; 1287 int fh_type; 1288 int err; 1289 1290 err = mnt_want_write(mnt); 1291 if (err) 1292 return err; 1293 1294 workdir = ovl_workdir_create(ofs, OVL_WORKDIR_NAME, false); 1295 err = PTR_ERR(workdir); 1296 if (IS_ERR_OR_NULL(workdir)) 1297 goto out; 1298 1299 ofs->workdir = workdir; 1300 1301 err = ovl_setup_trap(sb, ofs->workdir, &ofs->workdir_trap, "workdir"); 1302 if (err) 1303 goto out; 1304 1305 /* 1306 * Upper should support d_type, else whiteouts are visible. Given 1307 * workdir and upper are on same fs, we can do iterate_dir() on 1308 * workdir. This check requires successful creation of workdir in 1309 * previous step. 1310 */ 1311 err = ovl_check_d_type_supported(workpath); 1312 if (err < 0) 1313 goto out; 1314 1315 d_type = err; 1316 if (!d_type) 1317 pr_warn("upper fs needs to support d_type.\n"); 1318 1319 /* Check if upper/work fs supports O_TMPFILE */ 1320 tmpfile = ovl_do_tmpfile(ofs, ofs->workdir, S_IFREG | 0); 1321 ofs->tmpfile = !IS_ERR(tmpfile); 1322 if (ofs->tmpfile) 1323 fput(tmpfile); 1324 else 1325 pr_warn("upper fs does not support tmpfile.\n"); 1326 1327 1328 /* Check if upper/work fs supports RENAME_WHITEOUT */ 1329 err = ovl_check_rename_whiteout(ofs); 1330 if (err < 0) 1331 goto out; 1332 1333 rename_whiteout = err; 1334 if (!rename_whiteout) 1335 pr_warn("upper fs does not support RENAME_WHITEOUT.\n"); 1336 1337 /* 1338 * Check if upper/work fs supports (trusted|user).overlay.* xattr 1339 */ 1340 err = ovl_setxattr(ofs, ofs->workdir, OVL_XATTR_OPAQUE, "0", 1); 1341 if (err) { 1342 pr_warn("failed to set xattr on upper\n"); 1343 ofs->noxattr = true; 1344 if (ofs->config.index || ofs->config.metacopy) { 1345 ofs->config.index = false; 1346 ofs->config.metacopy = false; 1347 pr_warn("...falling back to index=off,metacopy=off.\n"); 1348 } 1349 /* 1350 * xattr support is required for persistent st_ino. 1351 * Without persistent st_ino, xino=auto falls back to xino=off. 1352 */ 1353 if (ofs->config.xino == OVL_XINO_AUTO) { 1354 ofs->config.xino = OVL_XINO_OFF; 1355 pr_warn("...falling back to xino=off.\n"); 1356 } 1357 if (err == -EPERM && !ofs->config.userxattr) 1358 pr_info("try mounting with 'userxattr' option\n"); 1359 err = 0; 1360 } else { 1361 ovl_removexattr(ofs, ofs->workdir, OVL_XATTR_OPAQUE); 1362 } 1363 1364 /* 1365 * We allowed sub-optimal upper fs configuration and don't want to break 1366 * users over kernel upgrade, but we never allowed remote upper fs, so 1367 * we can enforce strict requirements for remote upper fs. 1368 */ 1369 if (ovl_dentry_remote(ofs->workdir) && 1370 (!d_type || !rename_whiteout || ofs->noxattr)) { 1371 pr_err("upper fs missing required features.\n"); 1372 err = -EINVAL; 1373 goto out; 1374 } 1375 1376 /* 1377 * For volatile mount, create a incompat/volatile/dirty file to keep 1378 * track of it. 1379 */ 1380 if (ofs->config.ovl_volatile) { 1381 err = ovl_create_volatile_dirty(ofs); 1382 if (err < 0) { 1383 pr_err("Failed to create volatile/dirty file.\n"); 1384 goto out; 1385 } 1386 } 1387 1388 /* Check if upper/work fs supports file handles */ 1389 fh_type = ovl_can_decode_fh(ofs->workdir->d_sb); 1390 if (ofs->config.index && !fh_type) { 1391 ofs->config.index = false; 1392 pr_warn("upper fs does not support file handles, falling back to index=off.\n"); 1393 } 1394 1395 /* Check if upper fs has 32bit inode numbers */ 1396 if (fh_type != FILEID_INO32_GEN) 1397 ofs->xino_mode = -1; 1398 1399 /* NFS export of r/w mount depends on index */ 1400 if (ofs->config.nfs_export && !ofs->config.index) { 1401 pr_warn("NFS export requires \"index=on\", falling back to nfs_export=off.\n"); 1402 ofs->config.nfs_export = false; 1403 } 1404 out: 1405 mnt_drop_write(mnt); 1406 return err; 1407 } 1408 1409 static int ovl_get_workdir(struct super_block *sb, struct ovl_fs *ofs, 1410 const struct path *upperpath) 1411 { 1412 int err; 1413 struct path workpath = { }; 1414 1415 err = ovl_mount_dir(ofs->config.workdir, &workpath); 1416 if (err) 1417 goto out; 1418 1419 err = -EINVAL; 1420 if (upperpath->mnt != workpath.mnt) { 1421 pr_err("workdir and upperdir must reside under the same mount\n"); 1422 goto out; 1423 } 1424 if (!ovl_workdir_ok(workpath.dentry, upperpath->dentry)) { 1425 pr_err("workdir and upperdir must be separate subtrees\n"); 1426 goto out; 1427 } 1428 1429 ofs->workbasedir = dget(workpath.dentry); 1430 1431 if (ovl_inuse_trylock(ofs->workbasedir)) { 1432 ofs->workdir_locked = true; 1433 } else { 1434 err = ovl_report_in_use(ofs, "workdir"); 1435 if (err) 1436 goto out; 1437 } 1438 1439 err = ovl_setup_trap(sb, ofs->workbasedir, &ofs->workbasedir_trap, 1440 "workdir"); 1441 if (err) 1442 goto out; 1443 1444 err = ovl_make_workdir(sb, ofs, &workpath); 1445 1446 out: 1447 path_put(&workpath); 1448 1449 return err; 1450 } 1451 1452 static int ovl_get_indexdir(struct super_block *sb, struct ovl_fs *ofs, 1453 struct ovl_entry *oe, const struct path *upperpath) 1454 { 1455 struct vfsmount *mnt = ovl_upper_mnt(ofs); 1456 struct dentry *indexdir; 1457 int err; 1458 1459 err = mnt_want_write(mnt); 1460 if (err) 1461 return err; 1462 1463 /* Verify lower root is upper root origin */ 1464 err = ovl_verify_origin(ofs, upperpath->dentry, 1465 oe->lowerstack[0].dentry, true); 1466 if (err) { 1467 pr_err("failed to verify upper root origin\n"); 1468 goto out; 1469 } 1470 1471 /* index dir will act also as workdir */ 1472 iput(ofs->workdir_trap); 1473 ofs->workdir_trap = NULL; 1474 dput(ofs->workdir); 1475 ofs->workdir = NULL; 1476 indexdir = ovl_workdir_create(ofs, OVL_INDEXDIR_NAME, true); 1477 if (IS_ERR(indexdir)) { 1478 err = PTR_ERR(indexdir); 1479 } else if (indexdir) { 1480 ofs->indexdir = indexdir; 1481 ofs->workdir = dget(indexdir); 1482 1483 err = ovl_setup_trap(sb, ofs->indexdir, &ofs->indexdir_trap, 1484 "indexdir"); 1485 if (err) 1486 goto out; 1487 1488 /* 1489 * Verify upper root is exclusively associated with index dir. 1490 * Older kernels stored upper fh in ".overlay.origin" 1491 * xattr. If that xattr exists, verify that it is a match to 1492 * upper dir file handle. In any case, verify or set xattr 1493 * ".overlay.upper" to indicate that index may have 1494 * directory entries. 1495 */ 1496 if (ovl_check_origin_xattr(ofs, ofs->indexdir)) { 1497 err = ovl_verify_set_fh(ofs, ofs->indexdir, 1498 OVL_XATTR_ORIGIN, 1499 upperpath->dentry, true, false); 1500 if (err) 1501 pr_err("failed to verify index dir 'origin' xattr\n"); 1502 } 1503 err = ovl_verify_upper(ofs, ofs->indexdir, upperpath->dentry, 1504 true); 1505 if (err) 1506 pr_err("failed to verify index dir 'upper' xattr\n"); 1507 1508 /* Cleanup bad/stale/orphan index entries */ 1509 if (!err) 1510 err = ovl_indexdir_cleanup(ofs); 1511 } 1512 if (err || !ofs->indexdir) 1513 pr_warn("try deleting index dir or mounting with '-o index=off' to disable inodes index.\n"); 1514 1515 out: 1516 mnt_drop_write(mnt); 1517 return err; 1518 } 1519 1520 static bool ovl_lower_uuid_ok(struct ovl_fs *ofs, const uuid_t *uuid) 1521 { 1522 unsigned int i; 1523 1524 if (!ofs->config.nfs_export && !ovl_upper_mnt(ofs)) 1525 return true; 1526 1527 /* 1528 * We allow using single lower with null uuid for index and nfs_export 1529 * for example to support those features with single lower squashfs. 1530 * To avoid regressions in setups of overlay with re-formatted lower 1531 * squashfs, do not allow decoding origin with lower null uuid unless 1532 * user opted-in to one of the new features that require following the 1533 * lower inode of non-dir upper. 1534 */ 1535 if (ovl_allow_offline_changes(ofs) && uuid_is_null(uuid)) 1536 return false; 1537 1538 for (i = 0; i < ofs->numfs; i++) { 1539 /* 1540 * We use uuid to associate an overlay lower file handle with a 1541 * lower layer, so we can accept lower fs with null uuid as long 1542 * as all lower layers with null uuid are on the same fs. 1543 * if we detect multiple lower fs with the same uuid, we 1544 * disable lower file handle decoding on all of them. 1545 */ 1546 if (ofs->fs[i].is_lower && 1547 uuid_equal(&ofs->fs[i].sb->s_uuid, uuid)) { 1548 ofs->fs[i].bad_uuid = true; 1549 return false; 1550 } 1551 } 1552 return true; 1553 } 1554 1555 /* Get a unique fsid for the layer */ 1556 static int ovl_get_fsid(struct ovl_fs *ofs, const struct path *path) 1557 { 1558 struct super_block *sb = path->mnt->mnt_sb; 1559 unsigned int i; 1560 dev_t dev; 1561 int err; 1562 bool bad_uuid = false; 1563 bool warn = false; 1564 1565 for (i = 0; i < ofs->numfs; i++) { 1566 if (ofs->fs[i].sb == sb) 1567 return i; 1568 } 1569 1570 if (!ovl_lower_uuid_ok(ofs, &sb->s_uuid)) { 1571 bad_uuid = true; 1572 if (ofs->config.xino == OVL_XINO_AUTO) { 1573 ofs->config.xino = OVL_XINO_OFF; 1574 warn = true; 1575 } 1576 if (ofs->config.index || ofs->config.nfs_export) { 1577 ofs->config.index = false; 1578 ofs->config.nfs_export = false; 1579 warn = true; 1580 } 1581 if (warn) { 1582 pr_warn("%s uuid detected in lower fs '%pd2', falling back to xino=%s,index=off,nfs_export=off.\n", 1583 uuid_is_null(&sb->s_uuid) ? "null" : 1584 "conflicting", 1585 path->dentry, ovl_xino_str[ofs->config.xino]); 1586 } 1587 } 1588 1589 err = get_anon_bdev(&dev); 1590 if (err) { 1591 pr_err("failed to get anonymous bdev for lowerpath\n"); 1592 return err; 1593 } 1594 1595 ofs->fs[ofs->numfs].sb = sb; 1596 ofs->fs[ofs->numfs].pseudo_dev = dev; 1597 ofs->fs[ofs->numfs].bad_uuid = bad_uuid; 1598 1599 return ofs->numfs++; 1600 } 1601 1602 static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs, 1603 struct path *stack, unsigned int numlower, 1604 struct ovl_layer *layers) 1605 { 1606 int err; 1607 unsigned int i; 1608 1609 err = -ENOMEM; 1610 ofs->fs = kcalloc(numlower + 1, sizeof(struct ovl_sb), GFP_KERNEL); 1611 if (ofs->fs == NULL) 1612 goto out; 1613 1614 /* idx/fsid 0 are reserved for upper fs even with lower only overlay */ 1615 ofs->numfs++; 1616 1617 /* 1618 * All lower layers that share the same fs as upper layer, use the same 1619 * pseudo_dev as upper layer. Allocate fs[0].pseudo_dev even for lower 1620 * only overlay to simplify ovl_fs_free(). 1621 * is_lower will be set if upper fs is shared with a lower layer. 1622 */ 1623 err = get_anon_bdev(&ofs->fs[0].pseudo_dev); 1624 if (err) { 1625 pr_err("failed to get anonymous bdev for upper fs\n"); 1626 goto out; 1627 } 1628 1629 if (ovl_upper_mnt(ofs)) { 1630 ofs->fs[0].sb = ovl_upper_mnt(ofs)->mnt_sb; 1631 ofs->fs[0].is_lower = false; 1632 } 1633 1634 for (i = 0; i < numlower; i++) { 1635 struct vfsmount *mnt; 1636 struct inode *trap; 1637 int fsid; 1638 1639 err = fsid = ovl_get_fsid(ofs, &stack[i]); 1640 if (err < 0) 1641 goto out; 1642 1643 /* 1644 * Check if lower root conflicts with this overlay layers before 1645 * checking if it is in-use as upperdir/workdir of "another" 1646 * mount, because we do not bother to check in ovl_is_inuse() if 1647 * the upperdir/workdir is in fact in-use by our 1648 * upperdir/workdir. 1649 */ 1650 err = ovl_setup_trap(sb, stack[i].dentry, &trap, "lowerdir"); 1651 if (err) 1652 goto out; 1653 1654 if (ovl_is_inuse(stack[i].dentry)) { 1655 err = ovl_report_in_use(ofs, "lowerdir"); 1656 if (err) { 1657 iput(trap); 1658 goto out; 1659 } 1660 } 1661 1662 mnt = clone_private_mount(&stack[i]); 1663 err = PTR_ERR(mnt); 1664 if (IS_ERR(mnt)) { 1665 pr_err("failed to clone lowerpath\n"); 1666 iput(trap); 1667 goto out; 1668 } 1669 1670 /* 1671 * Make lower layers R/O. That way fchmod/fchown on lower file 1672 * will fail instead of modifying lower fs. 1673 */ 1674 mnt->mnt_flags |= MNT_READONLY | MNT_NOATIME; 1675 1676 layers[ofs->numlayer].trap = trap; 1677 layers[ofs->numlayer].mnt = mnt; 1678 layers[ofs->numlayer].idx = ofs->numlayer; 1679 layers[ofs->numlayer].fsid = fsid; 1680 layers[ofs->numlayer].fs = &ofs->fs[fsid]; 1681 ofs->numlayer++; 1682 ofs->fs[fsid].is_lower = true; 1683 } 1684 1685 /* 1686 * When all layers on same fs, overlay can use real inode numbers. 1687 * With mount option "xino=<on|auto>", mounter declares that there are 1688 * enough free high bits in underlying fs to hold the unique fsid. 1689 * If overlayfs does encounter underlying inodes using the high xino 1690 * bits reserved for fsid, it emits a warning and uses the original 1691 * inode number or a non persistent inode number allocated from a 1692 * dedicated range. 1693 */ 1694 if (ofs->numfs - !ovl_upper_mnt(ofs) == 1) { 1695 if (ofs->config.xino == OVL_XINO_ON) 1696 pr_info("\"xino=on\" is useless with all layers on same fs, ignore.\n"); 1697 ofs->xino_mode = 0; 1698 } else if (ofs->config.xino == OVL_XINO_OFF) { 1699 ofs->xino_mode = -1; 1700 } else if (ofs->xino_mode < 0) { 1701 /* 1702 * This is a roundup of number of bits needed for encoding 1703 * fsid, where fsid 0 is reserved for upper fs (even with 1704 * lower only overlay) +1 extra bit is reserved for the non 1705 * persistent inode number range that is used for resolving 1706 * xino lower bits overflow. 1707 */ 1708 BUILD_BUG_ON(ilog2(OVL_MAX_STACK) > 30); 1709 ofs->xino_mode = ilog2(ofs->numfs - 1) + 2; 1710 } 1711 1712 if (ofs->xino_mode > 0) { 1713 pr_info("\"xino\" feature enabled using %d upper inode bits.\n", 1714 ofs->xino_mode); 1715 } 1716 1717 err = 0; 1718 out: 1719 return err; 1720 } 1721 1722 static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb, 1723 const char *lower, unsigned int numlower, 1724 struct ovl_fs *ofs, struct ovl_layer *layers) 1725 { 1726 int err; 1727 struct path *stack = NULL; 1728 unsigned int i; 1729 struct ovl_entry *oe; 1730 1731 if (!ofs->config.upperdir && numlower == 1) { 1732 pr_err("at least 2 lowerdir are needed while upperdir nonexistent\n"); 1733 return ERR_PTR(-EINVAL); 1734 } 1735 1736 stack = kcalloc(numlower, sizeof(struct path), GFP_KERNEL); 1737 if (!stack) 1738 return ERR_PTR(-ENOMEM); 1739 1740 err = -EINVAL; 1741 for (i = 0; i < numlower; i++) { 1742 err = ovl_lower_dir(lower, &stack[i], ofs, &sb->s_stack_depth); 1743 if (err) 1744 goto out_err; 1745 1746 lower = strchr(lower, '\0') + 1; 1747 } 1748 1749 err = -EINVAL; 1750 sb->s_stack_depth++; 1751 if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) { 1752 pr_err("maximum fs stacking depth exceeded\n"); 1753 goto out_err; 1754 } 1755 1756 err = ovl_get_layers(sb, ofs, stack, numlower, layers); 1757 if (err) 1758 goto out_err; 1759 1760 err = -ENOMEM; 1761 oe = ovl_alloc_entry(numlower); 1762 if (!oe) 1763 goto out_err; 1764 1765 for (i = 0; i < numlower; i++) { 1766 oe->lowerstack[i].dentry = dget(stack[i].dentry); 1767 oe->lowerstack[i].layer = &ofs->layers[i+1]; 1768 } 1769 1770 out: 1771 for (i = 0; i < numlower; i++) 1772 path_put(&stack[i]); 1773 kfree(stack); 1774 1775 return oe; 1776 1777 out_err: 1778 oe = ERR_PTR(err); 1779 goto out; 1780 } 1781 1782 /* 1783 * Check if this layer root is a descendant of: 1784 * - another layer of this overlayfs instance 1785 * - upper/work dir of any overlayfs instance 1786 */ 1787 static int ovl_check_layer(struct super_block *sb, struct ovl_fs *ofs, 1788 struct dentry *dentry, const char *name, 1789 bool is_lower) 1790 { 1791 struct dentry *next = dentry, *parent; 1792 int err = 0; 1793 1794 if (!dentry) 1795 return 0; 1796 1797 parent = dget_parent(next); 1798 1799 /* Walk back ancestors to root (inclusive) looking for traps */ 1800 while (!err && parent != next) { 1801 if (is_lower && ovl_lookup_trap_inode(sb, parent)) { 1802 err = -ELOOP; 1803 pr_err("overlapping %s path\n", name); 1804 } else if (ovl_is_inuse(parent)) { 1805 err = ovl_report_in_use(ofs, name); 1806 } 1807 next = parent; 1808 parent = dget_parent(next); 1809 dput(next); 1810 } 1811 1812 dput(parent); 1813 1814 return err; 1815 } 1816 1817 /* 1818 * Check if any of the layers or work dirs overlap. 1819 */ 1820 static int ovl_check_overlapping_layers(struct super_block *sb, 1821 struct ovl_fs *ofs) 1822 { 1823 int i, err; 1824 1825 if (ovl_upper_mnt(ofs)) { 1826 err = ovl_check_layer(sb, ofs, ovl_upper_mnt(ofs)->mnt_root, 1827 "upperdir", false); 1828 if (err) 1829 return err; 1830 1831 /* 1832 * Checking workbasedir avoids hitting ovl_is_inuse(parent) of 1833 * this instance and covers overlapping work and index dirs, 1834 * unless work or index dir have been moved since created inside 1835 * workbasedir. In that case, we already have their traps in 1836 * inode cache and we will catch that case on lookup. 1837 */ 1838 err = ovl_check_layer(sb, ofs, ofs->workbasedir, "workdir", 1839 false); 1840 if (err) 1841 return err; 1842 } 1843 1844 for (i = 1; i < ofs->numlayer; i++) { 1845 err = ovl_check_layer(sb, ofs, 1846 ofs->layers[i].mnt->mnt_root, 1847 "lowerdir", true); 1848 if (err) 1849 return err; 1850 } 1851 1852 return 0; 1853 } 1854 1855 static struct dentry *ovl_get_root(struct super_block *sb, 1856 struct dentry *upperdentry, 1857 struct ovl_entry *oe) 1858 { 1859 struct dentry *root; 1860 struct ovl_path *lowerpath = &oe->lowerstack[0]; 1861 unsigned long ino = d_inode(lowerpath->dentry)->i_ino; 1862 int fsid = lowerpath->layer->fsid; 1863 struct ovl_inode_params oip = { 1864 .upperdentry = upperdentry, 1865 .lowerpath = lowerpath, 1866 }; 1867 1868 root = d_make_root(ovl_new_inode(sb, S_IFDIR, 0)); 1869 if (!root) 1870 return NULL; 1871 1872 root->d_fsdata = oe; 1873 1874 if (upperdentry) { 1875 /* Root inode uses upper st_ino/i_ino */ 1876 ino = d_inode(upperdentry)->i_ino; 1877 fsid = 0; 1878 ovl_dentry_set_upper_alias(root); 1879 if (ovl_is_impuredir(sb, upperdentry)) 1880 ovl_set_flag(OVL_IMPURE, d_inode(root)); 1881 } 1882 1883 /* Root is always merge -> can have whiteouts */ 1884 ovl_set_flag(OVL_WHITEOUTS, d_inode(root)); 1885 ovl_dentry_set_flag(OVL_E_CONNECTED, root); 1886 ovl_set_upperdata(d_inode(root)); 1887 ovl_inode_init(d_inode(root), &oip, ino, fsid); 1888 ovl_dentry_update_reval(root, upperdentry, DCACHE_OP_WEAK_REVALIDATE); 1889 1890 return root; 1891 } 1892 1893 static int ovl_fill_super(struct super_block *sb, void *data, int silent) 1894 { 1895 struct path upperpath = { }; 1896 struct dentry *root_dentry; 1897 struct ovl_entry *oe; 1898 struct ovl_fs *ofs; 1899 struct ovl_layer *layers; 1900 struct cred *cred; 1901 char *splitlower = NULL; 1902 unsigned int numlower; 1903 int err; 1904 1905 err = -EIO; 1906 if (WARN_ON(sb->s_user_ns != current_user_ns())) 1907 goto out; 1908 1909 sb->s_d_op = &ovl_dentry_operations; 1910 1911 err = -ENOMEM; 1912 ofs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL); 1913 if (!ofs) 1914 goto out; 1915 1916 err = -ENOMEM; 1917 ofs->creator_cred = cred = prepare_creds(); 1918 if (!cred) 1919 goto out_err; 1920 1921 /* Is there a reason anyone would want not to share whiteouts? */ 1922 ofs->share_whiteout = true; 1923 1924 ofs->config.index = ovl_index_def; 1925 ofs->config.uuid = true; 1926 ofs->config.nfs_export = ovl_nfs_export_def; 1927 ofs->config.xino = ovl_xino_def(); 1928 ofs->config.metacopy = ovl_metacopy_def; 1929 err = ovl_parse_opt((char *) data, &ofs->config); 1930 if (err) 1931 goto out_err; 1932 1933 err = -EINVAL; 1934 if (!ofs->config.lowerdir) { 1935 if (!silent) 1936 pr_err("missing 'lowerdir'\n"); 1937 goto out_err; 1938 } 1939 1940 err = -ENOMEM; 1941 splitlower = kstrdup(ofs->config.lowerdir, GFP_KERNEL); 1942 if (!splitlower) 1943 goto out_err; 1944 1945 err = -EINVAL; 1946 numlower = ovl_split_lowerdirs(splitlower); 1947 if (numlower > OVL_MAX_STACK) { 1948 pr_err("too many lower directories, limit is %d\n", 1949 OVL_MAX_STACK); 1950 goto out_err; 1951 } 1952 1953 err = -ENOMEM; 1954 layers = kcalloc(numlower + 1, sizeof(struct ovl_layer), GFP_KERNEL); 1955 if (!layers) 1956 goto out_err; 1957 1958 ofs->layers = layers; 1959 /* Layer 0 is reserved for upper even if there's no upper */ 1960 ofs->numlayer = 1; 1961 1962 sb->s_stack_depth = 0; 1963 sb->s_maxbytes = MAX_LFS_FILESIZE; 1964 atomic_long_set(&ofs->last_ino, 1); 1965 /* Assume underlying fs uses 32bit inodes unless proven otherwise */ 1966 if (ofs->config.xino != OVL_XINO_OFF) { 1967 ofs->xino_mode = BITS_PER_LONG - 32; 1968 if (!ofs->xino_mode) { 1969 pr_warn("xino not supported on 32bit kernel, falling back to xino=off.\n"); 1970 ofs->config.xino = OVL_XINO_OFF; 1971 } 1972 } 1973 1974 /* alloc/destroy_inode needed for setting up traps in inode cache */ 1975 sb->s_op = &ovl_super_operations; 1976 1977 if (ofs->config.upperdir) { 1978 struct super_block *upper_sb; 1979 1980 err = -EINVAL; 1981 if (!ofs->config.workdir) { 1982 pr_err("missing 'workdir'\n"); 1983 goto out_err; 1984 } 1985 1986 err = ovl_get_upper(sb, ofs, &layers[0], &upperpath); 1987 if (err) 1988 goto out_err; 1989 1990 upper_sb = ovl_upper_mnt(ofs)->mnt_sb; 1991 if (!ovl_should_sync(ofs)) { 1992 ofs->errseq = errseq_sample(&upper_sb->s_wb_err); 1993 if (errseq_check(&upper_sb->s_wb_err, ofs->errseq)) { 1994 err = -EIO; 1995 pr_err("Cannot mount volatile when upperdir has an unseen error. Sync upperdir fs to clear state.\n"); 1996 goto out_err; 1997 } 1998 } 1999 2000 err = ovl_get_workdir(sb, ofs, &upperpath); 2001 if (err) 2002 goto out_err; 2003 2004 if (!ofs->workdir) 2005 sb->s_flags |= SB_RDONLY; 2006 2007 sb->s_stack_depth = upper_sb->s_stack_depth; 2008 sb->s_time_gran = upper_sb->s_time_gran; 2009 } 2010 oe = ovl_get_lowerstack(sb, splitlower, numlower, ofs, layers); 2011 err = PTR_ERR(oe); 2012 if (IS_ERR(oe)) 2013 goto out_err; 2014 2015 /* If the upper fs is nonexistent, we mark overlayfs r/o too */ 2016 if (!ovl_upper_mnt(ofs)) 2017 sb->s_flags |= SB_RDONLY; 2018 2019 if (!ofs->config.uuid && ofs->numfs > 1) { 2020 pr_warn("The uuid=off requires a single fs for lower and upper, falling back to uuid=on.\n"); 2021 ofs->config.uuid = true; 2022 } 2023 2024 if (!ovl_force_readonly(ofs) && ofs->config.index) { 2025 err = ovl_get_indexdir(sb, ofs, oe, &upperpath); 2026 if (err) 2027 goto out_free_oe; 2028 2029 /* Force r/o mount with no index dir */ 2030 if (!ofs->indexdir) 2031 sb->s_flags |= SB_RDONLY; 2032 } 2033 2034 err = ovl_check_overlapping_layers(sb, ofs); 2035 if (err) 2036 goto out_free_oe; 2037 2038 /* Show index=off in /proc/mounts for forced r/o mount */ 2039 if (!ofs->indexdir) { 2040 ofs->config.index = false; 2041 if (ovl_upper_mnt(ofs) && ofs->config.nfs_export) { 2042 pr_warn("NFS export requires an index dir, falling back to nfs_export=off.\n"); 2043 ofs->config.nfs_export = false; 2044 } 2045 } 2046 2047 if (ofs->config.metacopy && ofs->config.nfs_export) { 2048 pr_warn("NFS export is not supported with metadata only copy up, falling back to nfs_export=off.\n"); 2049 ofs->config.nfs_export = false; 2050 } 2051 2052 if (ofs->config.nfs_export) 2053 sb->s_export_op = &ovl_export_operations; 2054 2055 /* Never override disk quota limits or use reserved space */ 2056 cap_lower(cred->cap_effective, CAP_SYS_RESOURCE); 2057 2058 sb->s_magic = OVERLAYFS_SUPER_MAGIC; 2059 sb->s_xattr = ofs->config.userxattr ? ovl_user_xattr_handlers : 2060 ovl_trusted_xattr_handlers; 2061 sb->s_fs_info = ofs; 2062 sb->s_flags |= SB_POSIXACL; 2063 sb->s_iflags |= SB_I_SKIP_SYNC; 2064 2065 err = -ENOMEM; 2066 root_dentry = ovl_get_root(sb, upperpath.dentry, oe); 2067 if (!root_dentry) 2068 goto out_free_oe; 2069 2070 mntput(upperpath.mnt); 2071 kfree(splitlower); 2072 2073 sb->s_root = root_dentry; 2074 2075 return 0; 2076 2077 out_free_oe: 2078 ovl_entry_stack_free(oe); 2079 kfree(oe); 2080 out_err: 2081 kfree(splitlower); 2082 path_put(&upperpath); 2083 ovl_free_fs(ofs); 2084 out: 2085 return err; 2086 } 2087 2088 static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags, 2089 const char *dev_name, void *raw_data) 2090 { 2091 return mount_nodev(fs_type, flags, raw_data, ovl_fill_super); 2092 } 2093 2094 static struct file_system_type ovl_fs_type = { 2095 .owner = THIS_MODULE, 2096 .name = "overlay", 2097 .fs_flags = FS_USERNS_MOUNT, 2098 .mount = ovl_mount, 2099 .kill_sb = kill_anon_super, 2100 }; 2101 MODULE_ALIAS_FS("overlay"); 2102 2103 static void ovl_inode_init_once(void *foo) 2104 { 2105 struct ovl_inode *oi = foo; 2106 2107 inode_init_once(&oi->vfs_inode); 2108 } 2109 2110 static int __init ovl_init(void) 2111 { 2112 int err; 2113 2114 ovl_inode_cachep = kmem_cache_create("ovl_inode", 2115 sizeof(struct ovl_inode), 0, 2116 (SLAB_RECLAIM_ACCOUNT| 2117 SLAB_MEM_SPREAD|SLAB_ACCOUNT), 2118 ovl_inode_init_once); 2119 if (ovl_inode_cachep == NULL) 2120 return -ENOMEM; 2121 2122 err = ovl_aio_request_cache_init(); 2123 if (!err) { 2124 err = register_filesystem(&ovl_fs_type); 2125 if (!err) 2126 return 0; 2127 2128 ovl_aio_request_cache_destroy(); 2129 } 2130 kmem_cache_destroy(ovl_inode_cachep); 2131 2132 return err; 2133 } 2134 2135 static void __exit ovl_exit(void) 2136 { 2137 unregister_filesystem(&ovl_fs_type); 2138 2139 /* 2140 * Make sure all delayed rcu free inodes are flushed before we 2141 * destroy cache. 2142 */ 2143 rcu_barrier(); 2144 kmem_cache_destroy(ovl_inode_cachep); 2145 ovl_aio_request_cache_destroy(); 2146 } 2147 2148 module_init(ovl_init); 2149 module_exit(ovl_exit); 2150