fs/overlayfs/dir.c

   1 /*
   2  *
   3  * Copyright (C) 2011 Novell Inc.
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 as published by
   7  * the Free Software Foundation.
   8  */
   9
  10 #include <linux/fs.h>
  11 #include <linux/namei.h>
  12 #include <linux/xattr.h>
  13 #include <linux/security.h>
  14 #include <linux/cred.h>
  15 #include "overlayfs.h"
  16
  17 void ovl_cleanup(struct inode *wdir, struct dentry *wdentry)
  18 {
  19         int err;
  20
  21         dget(wdentry);
  22         if (d_is_dir(wdentry))
  23                 err = ovl_do_rmdir(wdir, wdentry);
  24         else
  25                 err = ovl_do_unlink(wdir, wdentry);
  26         dput(wdentry);
  27
  28         if (err) {
  29                 pr_err("overlayfs: cleanup of '%pd2' failed (%i)\n",
  30                        wdentry, err);
  31         }
  32 }
  33
  34 struct dentry *ovl_lookup_temp(struct dentry *workdir, struct dentry *dentry)
  35 {
  36         struct dentry *temp;
  37         char name[20];
  38
  39         snprintf(name, sizeof(name), "#%lx", (unsigned long) dentry);
  40
  41         temp = lookup_one_len(name, workdir, strlen(name));
  42         if (!IS_ERR(temp) && temp->d_inode) {
  43                 pr_err("overlayfs: workdir/%s already exists\n", name);
  44                 dput(temp);
  45                 temp = ERR_PTR(-EIO);
  46         }
  47
  48         return temp;
  49 }
  50
  51 /* caller holds i_mutex on workdir */
  52 static struct dentry *ovl_whiteout(struct dentry *workdir,
  53                                    struct dentry *dentry)
  54 {
  55         int err;
  56         struct dentry *whiteout;
  57         struct inode *wdir = workdir->d_inode;
  58
  59         whiteout = ovl_lookup_temp(workdir, dentry);
  60         if (IS_ERR(whiteout))
  61                 return whiteout;
  62
  63         err = ovl_do_whiteout(wdir, whiteout);
  64         if (err) {
  65                 dput(whiteout);
  66                 whiteout = ERR_PTR(err);
  67         }
  68
  69         return whiteout;
  70 }
  71
  72 int ovl_create_real(struct inode *dir, struct dentry *newdentry,
  73                     struct kstat *stat, const char *link,
  74                     struct dentry *hardlink, bool debug)
  75 {
  76         int err;
  77
  78         if (newdentry->d_inode)
  79                 return -ESTALE;
  80
  81         if (hardlink) {
  82                 err = ovl_do_link(hardlink, dir, newdentry, debug);
  83         } else {
  84                 switch (stat->mode & S_IFMT) {
  85                 case S_IFREG:
  86                         err = ovl_do_create(dir, newdentry, stat->mode, debug);
  87                         break;
  88
  89                 case S_IFDIR:
  90                         err = ovl_do_mkdir(dir, newdentry, stat->mode, debug);
  91                         break;
  92
  93                 case S_IFCHR:
  94                 case S_IFBLK:
  95                 case S_IFIFO:
  96                 case S_IFSOCK:
  97                         err = ovl_do_mknod(dir, newdentry,
  98                                            stat->mode, stat->rdev, debug);
  99                         break;
 100
 101                 case S_IFLNK:
 102                         err = ovl_do_symlink(dir, newdentry, link, debug);
 103                         break;
 104
 105                 default:
 106                         err = -EPERM;
 107                 }
 108         }
 109         if (!err && WARN_ON(!newdentry->d_inode)) {
 110                 /*
 111                  * Not quite sure if non-instantiated dentry is legal or not.
 112                  * VFS doesn't seem to care so check and warn here.
 113                  */
 114                 err = -ENOENT;
 115         }
 116         return err;
 117 }
 118
 119 static int ovl_set_opaque(struct dentry *upperdentry)
 120 {
 121         return ovl_do_setxattr(upperdentry, OVL_XATTR_OPAQUE, "y", 1, 0);
 122 }
 123
 124 static void ovl_remove_opaque(struct dentry *upperdentry)
 125 {
 126         int err;
 127
 128         err = ovl_do_removexattr(upperdentry, OVL_XATTR_OPAQUE);
 129         if (err) {
 130                 pr_warn("overlayfs: failed to remove opaque from '%s' (%i)\n",
 131                         upperdentry->d_name.name, err);
 132         }
 133 }
 134
 135 static int ovl_dir_getattr(struct vfsmount *mnt, struct dentry *dentry,
 136                          struct kstat *stat)
 137 {
 138         int err;
 139         enum ovl_path_type type;
 140         struct path realpath;
 141         const struct cred *old_cred;
 142
 143         type = ovl_path_real(dentry, &realpath);
 144         old_cred = ovl_override_creds(dentry->d_sb);
 145         err = vfs_getattr(&realpath, stat);
 146         revert_creds(old_cred);
 147         if (err)
 148                 return err;
 149
 150         stat->dev = dentry->d_sb->s_dev;
 151         stat->ino = dentry->d_inode->i_ino;
 152
 153         /*
 154          * It's probably not worth it to count subdirs to get the
 155          * correct link count.  nlink=1 seems to pacify 'find' and
 156          * other utilities.
 157          */
 158         if (OVL_TYPE_MERGE(type))
 159                 stat->nlink = 1;
 160
 161         return 0;
 162 }
 163
 164 /* Common operations required to be done after creation of file on upper */
 165 static void ovl_instantiate(struct dentry *dentry, struct inode *inode,
 166                             struct dentry *newdentry)
 167 {
 168         ovl_dentry_version_inc(dentry->d_parent);
 169         ovl_dentry_update(dentry, newdentry);
 170         ovl_copyattr(newdentry->d_inode, inode);
 171         d_instantiate(dentry, inode);
 172 }
 173
 174 static int ovl_create_upper(struct dentry *dentry, struct inode *inode,
 175                             struct kstat *stat, const char *link,
 176                             struct dentry *hardlink)
 177 {
 178         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 179         struct inode *udir = upperdir->d_inode;
 180         struct dentry *newdentry;
 181         int err;
 182
 183         inode_lock_nested(udir, I_MUTEX_PARENT);
 184         newdentry = lookup_one_len(dentry->d_name.name, upperdir,
 185                                    dentry->d_name.len);
 186         err = PTR_ERR(newdentry);
 187         if (IS_ERR(newdentry))
 188                 goto out_unlock;
 189         err = ovl_create_real(udir, newdentry, stat, link, hardlink, false);
 190         if (err)
 191                 goto out_dput;
 192
 193         ovl_instantiate(dentry, inode, newdentry);
 194         newdentry = NULL;
 195 out_dput:
 196         dput(newdentry);
 197 out_unlock:
 198         inode_unlock(udir);
 199         return err;
 200 }
 201
 202 static int ovl_lock_rename_workdir(struct dentry *workdir,
 203                                    struct dentry *upperdir)
 204 {
 205         /* Workdir should not be the same as upperdir */
 206         if (workdir == upperdir)
 207                 goto err;
 208
 209         /* Workdir should not be subdir of upperdir and vice versa */
 210         if (lock_rename(workdir, upperdir) != NULL)
 211                 goto err_unlock;
 212
 213         return 0;
 214
 215 err_unlock:
 216         unlock_rename(workdir, upperdir);
 217 err:
 218         pr_err("overlayfs: failed to lock workdir+upperdir\n");
 219         return -EIO;
 220 }
 221
 222 static struct dentry *ovl_clear_empty(struct dentry *dentry,
 223                                       struct list_head *list)
 224 {
 225         struct dentry *workdir = ovl_workdir(dentry);
 226         struct inode *wdir = workdir->d_inode;
 227         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 228         struct inode *udir = upperdir->d_inode;
 229         struct path upperpath;
 230         struct dentry *upper;
 231         struct dentry *opaquedir;
 232         struct kstat stat;
 233         int err;
 234
 235         if (WARN_ON(!workdir))
 236                 return ERR_PTR(-EROFS);
 237
 238         err = ovl_lock_rename_workdir(workdir, upperdir);
 239         if (err)
 240                 goto out;
 241
 242         ovl_path_upper(dentry, &upperpath);
 243         err = vfs_getattr(&upperpath, &stat);
 244         if (err)
 245                 goto out_unlock;
 246
 247         err = -ESTALE;
 248         if (!S_ISDIR(stat.mode))
 249                 goto out_unlock;
 250         upper = upperpath.dentry;
 251         if (upper->d_parent->d_inode != udir)
 252                 goto out_unlock;
 253
 254         opaquedir = ovl_lookup_temp(workdir, dentry);
 255         err = PTR_ERR(opaquedir);
 256         if (IS_ERR(opaquedir))
 257                 goto out_unlock;
 258
 259         err = ovl_create_real(wdir, opaquedir, &stat, NULL, NULL, true);
 260         if (err)
 261                 goto out_dput;
 262
 263         err = ovl_copy_xattr(upper, opaquedir);
 264         if (err)
 265                 goto out_cleanup;
 266
 267         err = ovl_set_opaque(opaquedir);
 268         if (err)
 269                 goto out_cleanup;
 270
 271         inode_lock(opaquedir->d_inode);
 272         err = ovl_set_attr(opaquedir, &stat);
 273         inode_unlock(opaquedir->d_inode);
 274         if (err)
 275                 goto out_cleanup;
 276
 277         err = ovl_do_rename(wdir, opaquedir, udir, upper, RENAME_EXCHANGE);
 278         if (err)
 279                 goto out_cleanup;
 280
 281         ovl_cleanup_whiteouts(upper, list);
 282         ovl_cleanup(wdir, upper);
 283         unlock_rename(workdir, upperdir);
 284
 285         /* dentry's upper doesn't match now, get rid of it */
 286         d_drop(dentry);
 287
 288         return opaquedir;
 289
 290 out_cleanup:
 291         ovl_cleanup(wdir, opaquedir);
 292 out_dput:
 293         dput(opaquedir);
 294 out_unlock:
 295         unlock_rename(workdir, upperdir);
 296 out:
 297         return ERR_PTR(err);
 298 }
 299
 300 static struct dentry *ovl_check_empty_and_clear(struct dentry *dentry)
 301 {
 302         int err;
 303         struct dentry *ret = NULL;
 304         LIST_HEAD(list);
 305
 306         err = ovl_check_empty_dir(dentry, &list);
 307         if (err)
 308                 ret = ERR_PTR(err);
 309         else {
 310                 /*
 311                  * If no upperdentry then skip clearing whiteouts.
 312                  *
 313                  * Can race with copy-up, since we don't hold the upperdir
 314                  * mutex.  Doesn't matter, since copy-up can't create a
 315                  * non-empty directory from an empty one.
 316                  */
 317                 if (ovl_dentry_upper(dentry))
 318                         ret = ovl_clear_empty(dentry, &list);
 319         }
 320
 321         ovl_cache_free(&list);
 322
 323         return ret;
 324 }
 325
 326 static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
 327                                     struct kstat *stat, const char *link,
 328                                     struct dentry *hardlink)
 329 {
 330         struct dentry *workdir = ovl_workdir(dentry);
 331         struct inode *wdir = workdir->d_inode;
 332         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 333         struct inode *udir = upperdir->d_inode;
 334         struct dentry *upper;
 335         struct dentry *newdentry;
 336         int err;
 337
 338         if (WARN_ON(!workdir))
 339                 return -EROFS;
 340
 341         err = ovl_lock_rename_workdir(workdir, upperdir);
 342         if (err)
 343                 goto out;
 344
 345         newdentry = ovl_lookup_temp(workdir, dentry);
 346         err = PTR_ERR(newdentry);
 347         if (IS_ERR(newdentry))
 348                 goto out_unlock;
 349
 350         upper = lookup_one_len(dentry->d_name.name, upperdir,
 351                                dentry->d_name.len);
 352         err = PTR_ERR(upper);
 353         if (IS_ERR(upper))
 354                 goto out_dput;
 355
 356         err = ovl_create_real(wdir, newdentry, stat, link, hardlink, true);
 357         if (err)
 358                 goto out_dput2;
 359
 360         /*
 361          * mode could have been mutilated due to umask (e.g. sgid directory)
 362          */
 363         if (!S_ISLNK(stat->mode) && newdentry->d_inode->i_mode != stat->mode) {
 364                 struct iattr attr = {
 365                         .ia_valid = ATTR_MODE,
 366                         .ia_mode = stat->mode,
 367                 };
 368                 inode_lock(newdentry->d_inode);
 369                 err = notify_change(newdentry, &attr, NULL);
 370                 inode_unlock(newdentry->d_inode);
 371                 if (err)
 372                         goto out_cleanup;
 373         }
 374
 375         if (S_ISDIR(stat->mode)) {
 376                 err = ovl_set_opaque(newdentry);
 377                 if (err)
 378                         goto out_cleanup;
 379
 380                 err = ovl_do_rename(wdir, newdentry, udir, upper,
 381                                     RENAME_EXCHANGE);
 382                 if (err)
 383                         goto out_cleanup;
 384
 385                 ovl_cleanup(wdir, upper);
 386         } else {
 387                 err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
 388                 if (err)
 389                         goto out_cleanup;
 390         }
 391         ovl_instantiate(dentry, inode, newdentry);
 392         newdentry = NULL;
 393 out_dput2:
 394         dput(upper);
 395 out_dput:
 396         dput(newdentry);
 397 out_unlock:
 398         unlock_rename(workdir, upperdir);
 399 out:
 400         return err;
 401
 402 out_cleanup:
 403         ovl_cleanup(wdir, newdentry);
 404         goto out_dput2;
 405 }
 406
 407 static int ovl_create_or_link(struct dentry *dentry, int mode, dev_t rdev,
 408                               const char *link, struct dentry *hardlink)
 409 {
 410         int err;
 411         struct inode *inode;
 412         const struct cred *old_cred;
 413         struct cred *override_cred;
 414         struct kstat stat = {
 415                 .rdev = rdev,
 416         };
 417
 418         err = -ENOMEM;
 419         inode = ovl_new_inode(dentry->d_sb, mode, dentry->d_fsdata);
 420         if (!inode)
 421                 goto out;
 422
 423         err = ovl_copy_up(dentry->d_parent);
 424         if (err)
 425                 goto out_iput;
 426
 427         inode_init_owner(inode, dentry->d_parent->d_inode, mode);
 428         stat.mode = inode->i_mode;
 429
 430         old_cred = ovl_override_creds(dentry->d_sb);
 431         err = -ENOMEM;
 432         override_cred = prepare_creds();
 433         if (override_cred) {
 434                 override_cred->fsuid = inode->i_uid;
 435                 override_cred->fsgid = inode->i_gid;
 436                 put_cred(override_creds(override_cred));
 437                 put_cred(override_cred);
 438
 439                 if (!ovl_dentry_is_opaque(dentry))
 440                         err = ovl_create_upper(dentry, inode, &stat, link,
 441                                                 hardlink);
 442                 else
 443                         err = ovl_create_over_whiteout(dentry, inode, &stat,
 444                                                         link, hardlink);
 445         }
 446         revert_creds(old_cred);
 447         if (!err) {
 448                 struct inode *realinode = d_inode(ovl_dentry_upper(dentry));
 449
 450                 WARN_ON(inode->i_mode != realinode->i_mode);
 451                 WARN_ON(!uid_eq(inode->i_uid, realinode->i_uid));
 452                 WARN_ON(!gid_eq(inode->i_gid, realinode->i_gid));
 453                 inode = NULL;
 454         }
 455 out_iput:
 456         iput(inode);
 457 out:
 458         return err;
 459 }
 460
 461 static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
 462                              const char *link)
 463 {
 464         int err;
 465
 466         err = ovl_want_write(dentry);
 467         if (!err) {
 468                 err = ovl_create_or_link(dentry, mode, rdev, link, NULL);
 469                 ovl_drop_write(dentry);
 470         }
 471
 472         return err;
 473 }
 474
 475 static int ovl_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 476                       bool excl)
 477 {
 478         return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL);
 479 }
 480
 481 static int ovl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 482 {
 483         return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL);
 484 }
 485
 486 static int ovl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
 487                      dev_t rdev)
 488 {
 489         /* Don't allow creation of "whiteout" on overlay */
 490         if (S_ISCHR(mode) && rdev == WHITEOUT_DEV)
 491                 return -EPERM;
 492
 493         return ovl_create_object(dentry, mode, rdev, NULL);
 494 }
 495
 496 static int ovl_symlink(struct inode *dir, struct dentry *dentry,
 497                        const char *link)
 498 {
 499         return ovl_create_object(dentry, S_IFLNK, 0, link);
 500 }
 501
 502 static int ovl_link(struct dentry *old, struct inode *newdir,
 503                     struct dentry *new)
 504 {
 505         int err;
 506         struct dentry *upper;
 507
 508         err = ovl_want_write(old);
 509         if (err)
 510                 goto out;
 511
 512         err = ovl_copy_up(old);
 513         if (err)
 514                 goto out_drop_write;
 515
 516         upper = ovl_dentry_upper(old);
 517         err = ovl_create_or_link(new, upper->d_inode->i_mode, 0, NULL, upper);
 518
 519 out_drop_write:
 520         ovl_drop_write(old);
 521 out:
 522         return err;
 523 }
 524
 525 static int ovl_remove_and_whiteout(struct dentry *dentry, bool is_dir)
 526 {
 527         struct dentry *workdir = ovl_workdir(dentry);
 528         struct inode *wdir = workdir->d_inode;
 529         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 530         struct inode *udir = upperdir->d_inode;
 531         struct dentry *whiteout;
 532         struct dentry *upper;
 533         struct dentry *opaquedir = NULL;
 534         int err;
 535         int flags = 0;
 536
 537         if (WARN_ON(!workdir))
 538                 return -EROFS;
 539
 540         if (is_dir) {
 541                 if (OVL_TYPE_MERGE_OR_LOWER(ovl_path_type(dentry))) {
 542                         opaquedir = ovl_check_empty_and_clear(dentry);
 543                         err = PTR_ERR(opaquedir);
 544                         if (IS_ERR(opaquedir))
 545                                 goto out;
 546                 } else {
 547                         LIST_HEAD(list);
 548
 549                         /*
 550                          * When removing an empty opaque directory, then it
 551                          * makes no sense to replace it with an exact replica of
 552                          * itself.  But emptiness still needs to be checked.
 553                          */
 554                         err = ovl_check_empty_dir(dentry, &list);
 555                         ovl_cache_free(&list);
 556                         if (err)
 557                                 goto out;
 558                 }
 559         }
 560
 561         err = ovl_lock_rename_workdir(workdir, upperdir);
 562         if (err)
 563                 goto out_dput;
 564
 565         upper = lookup_one_len(dentry->d_name.name, upperdir,
 566                                dentry->d_name.len);
 567         err = PTR_ERR(upper);
 568         if (IS_ERR(upper))
 569                 goto out_unlock;
 570
 571         err = -ESTALE;
 572         if ((opaquedir && upper != opaquedir) ||
 573             (!opaquedir && ovl_dentry_upper(dentry) &&
 574              upper != ovl_dentry_upper(dentry))) {
 575                 goto out_dput_upper;
 576         }
 577
 578         whiteout = ovl_whiteout(workdir, dentry);
 579         err = PTR_ERR(whiteout);
 580         if (IS_ERR(whiteout))
 581                 goto out_dput_upper;
 582
 583         if (d_is_dir(upper))
 584                 flags = RENAME_EXCHANGE;
 585
 586         err = ovl_do_rename(wdir, whiteout, udir, upper, flags);
 587         if (err)
 588                 goto kill_whiteout;
 589         if (flags)
 590                 ovl_cleanup(wdir, upper);
 591
 592         ovl_dentry_version_inc(dentry->d_parent);
 593 out_d_drop:
 594         d_drop(dentry);
 595         dput(whiteout);
 596 out_dput_upper:
 597         dput(upper);
 598 out_unlock:
 599         unlock_rename(workdir, upperdir);
 600 out_dput:
 601         dput(opaquedir);
 602 out:
 603         return err;
 604
 605 kill_whiteout:
 606         ovl_cleanup(wdir, whiteout);
 607         goto out_d_drop;
 608 }
 609
 610 static int ovl_remove_upper(struct dentry *dentry, bool is_dir)
 611 {
 612         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 613         struct inode *dir = upperdir->d_inode;
 614         struct dentry *upper;
 615         int err;
 616
 617         inode_lock_nested(dir, I_MUTEX_PARENT);
 618         upper = lookup_one_len(dentry->d_name.name, upperdir,
 619                                dentry->d_name.len);
 620         err = PTR_ERR(upper);
 621         if (IS_ERR(upper))
 622                 goto out_unlock;
 623
 624         err = -ESTALE;
 625         if (upper == ovl_dentry_upper(dentry)) {
 626                 if (is_dir)
 627                         err = vfs_rmdir(dir, upper);
 628                 else
 629                         err = vfs_unlink(dir, upper, NULL);
 630                 ovl_dentry_version_inc(dentry->d_parent);
 631         }
 632         dput(upper);
 633
 634         /*
 635          * Keeping this dentry hashed would mean having to release
 636          * upperpath/lowerpath, which could only be done if we are the
 637          * sole user of this dentry.  Too tricky...  Just unhash for
 638          * now.
 639          */
 640         if (!err)
 641                 d_drop(dentry);
 642 out_unlock:
 643         inode_unlock(dir);
 644
 645         return err;
 646 }
 647
 648 static inline int ovl_check_sticky(struct dentry *dentry)
 649 {
 650         struct inode *dir = ovl_dentry_real(dentry->d_parent)->d_inode;
 651         struct inode *inode = ovl_dentry_real(dentry)->d_inode;
 652
 653         if (check_sticky(dir, inode))
 654                 return -EPERM;
 655
 656         return 0;
 657 }
 658
 659 static int ovl_do_remove(struct dentry *dentry, bool is_dir)
 660 {
 661         enum ovl_path_type type;
 662         int err;
 663         const struct cred *old_cred;
 664
 665
 666         err = ovl_check_sticky(dentry);
 667         if (err)
 668                 goto out;
 669
 670         err = ovl_want_write(dentry);
 671         if (err)
 672                 goto out;
 673
 674         err = ovl_copy_up(dentry->d_parent);
 675         if (err)
 676                 goto out_drop_write;
 677
 678         type = ovl_path_type(dentry);
 679
 680         old_cred = ovl_override_creds(dentry->d_sb);
 681         if (OVL_TYPE_PURE_UPPER(type))
 682                 err = ovl_remove_upper(dentry, is_dir);
 683         else
 684                 err = ovl_remove_and_whiteout(dentry, is_dir);
 685         revert_creds(old_cred);
 686 out_drop_write:
 687         ovl_drop_write(dentry);
 688 out:
 689         return err;
 690 }
 691
 692 static int ovl_unlink(struct inode *dir, struct dentry *dentry)
 693 {
 694         return ovl_do_remove(dentry, false);
 695 }
 696
 697 static int ovl_rmdir(struct inode *dir, struct dentry *dentry)
 698 {
 699         return ovl_do_remove(dentry, true);
 700 }
 701
 702 static int ovl_rename2(struct inode *olddir, struct dentry *old,
 703                        struct inode *newdir, struct dentry *new,
 704                        unsigned int flags)
 705 {
 706         int err;
 707         enum ovl_path_type old_type;
 708         enum ovl_path_type new_type;
 709         struct dentry *old_upperdir;
 710         struct dentry *new_upperdir;
 711         struct dentry *olddentry;
 712         struct dentry *newdentry;
 713         struct dentry *trap;
 714         bool old_opaque;
 715         bool new_opaque;
 716         bool cleanup_whiteout = false;
 717         bool overwrite = !(flags & RENAME_EXCHANGE);
 718         bool is_dir = d_is_dir(old);
 719         bool new_is_dir = false;
 720         struct dentry *opaquedir = NULL;
 721         const struct cred *old_cred = NULL;
 722
 723         err = -EINVAL;
 724         if (flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE))
 725                 goto out;
 726
 727         flags &= ~RENAME_NOREPLACE;
 728
 729         err = ovl_check_sticky(old);
 730         if (err)
 731                 goto out;
 732
 733         /* Don't copy up directory trees */
 734         old_type = ovl_path_type(old);
 735         err = -EXDEV;
 736         if (OVL_TYPE_MERGE_OR_LOWER(old_type) && is_dir)
 737                 goto out;
 738
 739         if (new->d_inode) {
 740                 err = ovl_check_sticky(new);
 741                 if (err)
 742                         goto out;
 743
 744                 if (d_is_dir(new))
 745                         new_is_dir = true;
 746
 747                 new_type = ovl_path_type(new);
 748                 err = -EXDEV;
 749                 if (!overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir)
 750                         goto out;
 751
 752                 err = 0;
 753                 if (!OVL_TYPE_UPPER(new_type) && !OVL_TYPE_UPPER(old_type)) {
 754                         if (ovl_dentry_lower(old)->d_inode ==
 755                             ovl_dentry_lower(new)->d_inode)
 756                                 goto out;
 757                 }
 758                 if (OVL_TYPE_UPPER(new_type) && OVL_TYPE_UPPER(old_type)) {
 759                         if (ovl_dentry_upper(old)->d_inode ==
 760                             ovl_dentry_upper(new)->d_inode)
 761                                 goto out;
 762                 }
 763         } else {
 764                 if (ovl_dentry_is_opaque(new))
 765                         new_type = __OVL_PATH_UPPER;
 766                 else
 767                         new_type = __OVL_PATH_UPPER | __OVL_PATH_PURE;
 768         }
 769
 770         err = ovl_want_write(old);
 771         if (err)
 772                 goto out;
 773
 774         err = ovl_copy_up(old);
 775         if (err)
 776                 goto out_drop_write;
 777
 778         err = ovl_copy_up(new->d_parent);
 779         if (err)
 780                 goto out_drop_write;
 781         if (!overwrite) {
 782                 err = ovl_copy_up(new);
 783                 if (err)
 784                         goto out_drop_write;
 785         }
 786
 787         old_opaque = !OVL_TYPE_PURE_UPPER(old_type);
 788         new_opaque = !OVL_TYPE_PURE_UPPER(new_type);
 789
 790         old_cred = ovl_override_creds(old->d_sb);
 791
 792         if (overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir) {
 793                 opaquedir = ovl_check_empty_and_clear(new);
 794                 err = PTR_ERR(opaquedir);
 795                 if (IS_ERR(opaquedir)) {
 796                         opaquedir = NULL;
 797                         goto out_revert_creds;
 798                 }
 799         }
 800
 801         if (overwrite) {
 802                 if (old_opaque) {
 803                         if (new->d_inode || !new_opaque) {
 804                                 /* Whiteout source */
 805                                 flags |= RENAME_WHITEOUT;
 806                         } else {
 807                                 /* Switch whiteouts */
 808                                 flags |= RENAME_EXCHANGE;
 809                         }
 810                 } else if (is_dir && !new->d_inode && new_opaque) {
 811                         flags |= RENAME_EXCHANGE;
 812                         cleanup_whiteout = true;
 813                 }
 814         }
 815
 816         old_upperdir = ovl_dentry_upper(old->d_parent);
 817         new_upperdir = ovl_dentry_upper(new->d_parent);
 818
 819         trap = lock_rename(new_upperdir, old_upperdir);
 820
 821
 822         olddentry = lookup_one_len(old->d_name.name, old_upperdir,
 823                                    old->d_name.len);
 824         err = PTR_ERR(olddentry);
 825         if (IS_ERR(olddentry))
 826                 goto out_unlock;
 827
 828         err = -ESTALE;
 829         if (olddentry != ovl_dentry_upper(old))
 830                 goto out_dput_old;
 831
 832         newdentry = lookup_one_len(new->d_name.name, new_upperdir,
 833                                    new->d_name.len);
 834         err = PTR_ERR(newdentry);
 835         if (IS_ERR(newdentry))
 836                 goto out_dput_old;
 837
 838         err = -ESTALE;
 839         if (ovl_dentry_upper(new)) {
 840                 if (opaquedir) {
 841                         if (newdentry != opaquedir)
 842                                 goto out_dput;
 843                 } else {
 844                         if (newdentry != ovl_dentry_upper(new))
 845                                 goto out_dput;
 846                 }
 847         } else {
 848                 if (!d_is_negative(newdentry) &&
 849                     (!new_opaque || !ovl_is_whiteout(newdentry)))
 850                         goto out_dput;
 851         }
 852
 853         if (olddentry == trap)
 854                 goto out_dput;
 855         if (newdentry == trap)
 856                 goto out_dput;
 857
 858         if (is_dir && !old_opaque && new_opaque) {
 859                 err = ovl_set_opaque(olddentry);
 860                 if (err)
 861                         goto out_dput;
 862         }
 863         if (!overwrite && new_is_dir && old_opaque && !new_opaque) {
 864                 err = ovl_set_opaque(newdentry);
 865                 if (err)
 866                         goto out_dput;
 867         }
 868
 869         if (old_opaque || new_opaque) {
 870                 err = ovl_do_rename(old_upperdir->d_inode, olddentry,
 871                                     new_upperdir->d_inode, newdentry,
 872                                     flags);
 873         } else {
 874                 /* No debug for the plain case */
 875                 BUG_ON(flags & ~RENAME_EXCHANGE);
 876                 err = vfs_rename(old_upperdir->d_inode, olddentry,
 877                                  new_upperdir->d_inode, newdentry,
 878                                  NULL, flags);
 879         }
 880
 881         if (err) {
 882                 if (is_dir && !old_opaque && new_opaque)
 883                         ovl_remove_opaque(olddentry);
 884                 if (!overwrite && new_is_dir && old_opaque && !new_opaque)
 885                         ovl_remove_opaque(newdentry);
 886                 goto out_dput;
 887         }
 888
 889         if (is_dir && old_opaque && !new_opaque)
 890                 ovl_remove_opaque(olddentry);
 891         if (!overwrite && new_is_dir && !old_opaque && new_opaque)
 892                 ovl_remove_opaque(newdentry);
 893
 894         /*
 895          * Old dentry now lives in different location. Dentries in
 896          * lowerstack are stale. We cannot drop them here because
 897          * access to them is lockless. This could be only pure upper
 898          * or opaque directory - numlower is zero. Or upper non-dir
 899          * entry - its pureness is tracked by flag opaque.
 900          */
 901         if (old_opaque != new_opaque) {
 902                 ovl_dentry_set_opaque(old, new_opaque);
 903                 if (!overwrite)
 904                         ovl_dentry_set_opaque(new, old_opaque);
 905         }
 906
 907         if (cleanup_whiteout)
 908                 ovl_cleanup(old_upperdir->d_inode, newdentry);
 909
 910         ovl_dentry_version_inc(old->d_parent);
 911         ovl_dentry_version_inc(new->d_parent);
 912
 913 out_dput:
 914         dput(newdentry);
 915 out_dput_old:
 916         dput(olddentry);
 917 out_unlock:
 918         unlock_rename(new_upperdir, old_upperdir);
 919 out_revert_creds:
 920         revert_creds(old_cred);
 921 out_drop_write:
 922         ovl_drop_write(old);
 923 out:
 924         dput(opaquedir);
 925         return err;
 926 }
 927
 928 const struct inode_operations ovl_dir_inode_operations = {
 929         .lookup         = ovl_lookup,
 930         .mkdir          = ovl_mkdir,
 931         .symlink        = ovl_symlink,
 932         .unlink         = ovl_unlink,
 933         .rmdir          = ovl_rmdir,
 934         .rename2        = ovl_rename2,
 935         .link           = ovl_link,
 936         .setattr        = ovl_setattr,
 937         .create         = ovl_create,
 938         .mknod          = ovl_mknod,
 939         .permission     = ovl_permission,
 940         .getattr        = ovl_dir_getattr,
 941         .setxattr       = ovl_setxattr,
 942         .getxattr       = ovl_getxattr,
 943         .listxattr      = ovl_listxattr,
 944         .removexattr    = ovl_removexattr,
 945         .get_acl        = ovl_get_acl,
 946 };