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