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 static int ovl_create_upper(struct dentry *dentry, struct inode *inode,
 162                             struct kstat *stat, const char *link,
 163                             struct dentry *hardlink)
 164 {
 165         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 166         struct inode *udir = upperdir->d_inode;
 167         struct dentry *newdentry;
 168         int err;
 169
 170         inode_lock_nested(udir, I_MUTEX_PARENT);
 171         newdentry = lookup_one_len(dentry->d_name.name, upperdir,
 172                                    dentry->d_name.len);
 173         err = PTR_ERR(newdentry);
 174         if (IS_ERR(newdentry))
 175                 goto out_unlock;
 176         err = ovl_create_real(udir, newdentry, stat, link, hardlink, false);
 177         if (err)
 178                 goto out_dput;
 179
 180         ovl_dentry_version_inc(dentry->d_parent);
 181         ovl_dentry_update(dentry, newdentry);
 182         ovl_copyattr(newdentry->d_inode, inode);
 183         d_instantiate(dentry, inode);
 184         newdentry = NULL;
 185 out_dput:
 186         dput(newdentry);
 187 out_unlock:
 188         inode_unlock(udir);
 189         return err;
 190 }
 191
 192 static int ovl_lock_rename_workdir(struct dentry *workdir,
 193                                    struct dentry *upperdir)
 194 {
 195         /* Workdir should not be the same as upperdir */
 196         if (workdir == upperdir)
 197                 goto err;
 198
 199         /* Workdir should not be subdir of upperdir and vice versa */
 200         if (lock_rename(workdir, upperdir) != NULL)
 201                 goto err_unlock;
 202
 203         return 0;
 204
 205 err_unlock:
 206         unlock_rename(workdir, upperdir);
 207 err:
 208         pr_err("overlayfs: failed to lock workdir+upperdir\n");
 209         return -EIO;
 210 }
 211
 212 static struct dentry *ovl_clear_empty(struct dentry *dentry,
 213                                       struct list_head *list)
 214 {
 215         struct dentry *workdir = ovl_workdir(dentry);
 216         struct inode *wdir = workdir->d_inode;
 217         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 218         struct inode *udir = upperdir->d_inode;
 219         struct path upperpath;
 220         struct dentry *upper;
 221         struct dentry *opaquedir;
 222         struct kstat stat;
 223         int err;
 224
 225         if (WARN_ON(!workdir))
 226                 return ERR_PTR(-EROFS);
 227
 228         err = ovl_lock_rename_workdir(workdir, upperdir);
 229         if (err)
 230                 goto out;
 231
 232         ovl_path_upper(dentry, &upperpath);
 233         err = vfs_getattr(&upperpath, &stat);
 234         if (err)
 235                 goto out_unlock;
 236
 237         err = -ESTALE;
 238         if (!S_ISDIR(stat.mode))
 239                 goto out_unlock;
 240         upper = upperpath.dentry;
 241         if (upper->d_parent->d_inode != udir)
 242                 goto out_unlock;
 243
 244         opaquedir = ovl_lookup_temp(workdir, dentry);
 245         err = PTR_ERR(opaquedir);
 246         if (IS_ERR(opaquedir))
 247                 goto out_unlock;
 248
 249         err = ovl_create_real(wdir, opaquedir, &stat, NULL, NULL, true);
 250         if (err)
 251                 goto out_dput;
 252
 253         err = ovl_copy_xattr(upper, opaquedir);
 254         if (err)
 255                 goto out_cleanup;
 256
 257         err = ovl_set_opaque(opaquedir);
 258         if (err)
 259                 goto out_cleanup;
 260
 261         inode_lock(opaquedir->d_inode);
 262         err = ovl_set_attr(opaquedir, &stat);
 263         inode_unlock(opaquedir->d_inode);
 264         if (err)
 265                 goto out_cleanup;
 266
 267         err = ovl_do_rename(wdir, opaquedir, udir, upper, RENAME_EXCHANGE);
 268         if (err)
 269                 goto out_cleanup;
 270
 271         ovl_cleanup_whiteouts(upper, list);
 272         ovl_cleanup(wdir, upper);
 273         unlock_rename(workdir, upperdir);
 274
 275         /* dentry's upper doesn't match now, get rid of it */
 276         d_drop(dentry);
 277
 278         return opaquedir;
 279
 280 out_cleanup:
 281         ovl_cleanup(wdir, opaquedir);
 282 out_dput:
 283         dput(opaquedir);
 284 out_unlock:
 285         unlock_rename(workdir, upperdir);
 286 out:
 287         return ERR_PTR(err);
 288 }
 289
 290 static struct dentry *ovl_check_empty_and_clear(struct dentry *dentry)
 291 {
 292         int err;
 293         struct dentry *ret = NULL;
 294         LIST_HEAD(list);
 295
 296         err = ovl_check_empty_dir(dentry, &list);
 297         if (err)
 298                 ret = ERR_PTR(err);
 299         else {
 300                 /*
 301                  * If no upperdentry then skip clearing whiteouts.
 302                  *
 303                  * Can race with copy-up, since we don't hold the upperdir
 304                  * mutex.  Doesn't matter, since copy-up can't create a
 305                  * non-empty directory from an empty one.
 306                  */
 307                 if (ovl_dentry_upper(dentry))
 308                         ret = ovl_clear_empty(dentry, &list);
 309         }
 310
 311         ovl_cache_free(&list);
 312
 313         return ret;
 314 }
 315
 316 static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
 317                                     struct kstat *stat, const char *link,
 318                                     struct dentry *hardlink)
 319 {
 320         struct dentry *workdir = ovl_workdir(dentry);
 321         struct inode *wdir = workdir->d_inode;
 322         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 323         struct inode *udir = upperdir->d_inode;
 324         struct dentry *upper;
 325         struct dentry *newdentry;
 326         int err;
 327
 328         if (WARN_ON(!workdir))
 329                 return -EROFS;
 330
 331         err = ovl_lock_rename_workdir(workdir, upperdir);
 332         if (err)
 333                 goto out;
 334
 335         newdentry = ovl_lookup_temp(workdir, dentry);
 336         err = PTR_ERR(newdentry);
 337         if (IS_ERR(newdentry))
 338                 goto out_unlock;
 339
 340         upper = lookup_one_len(dentry->d_name.name, upperdir,
 341                                dentry->d_name.len);
 342         err = PTR_ERR(upper);
 343         if (IS_ERR(upper))
 344                 goto out_dput;
 345
 346         err = ovl_create_real(wdir, newdentry, stat, link, hardlink, true);
 347         if (err)
 348                 goto out_dput2;
 349
 350         if (S_ISDIR(stat->mode)) {
 351                 err = ovl_set_opaque(newdentry);
 352                 if (err)
 353                         goto out_cleanup;
 354
 355                 err = ovl_do_rename(wdir, newdentry, udir, upper,
 356                                     RENAME_EXCHANGE);
 357                 if (err)
 358                         goto out_cleanup;
 359
 360                 ovl_cleanup(wdir, upper);
 361         } else {
 362                 err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
 363                 if (err)
 364                         goto out_cleanup;
 365         }
 366         ovl_dentry_version_inc(dentry->d_parent);
 367         ovl_dentry_update(dentry, newdentry);
 368         ovl_copyattr(newdentry->d_inode, inode);
 369         d_instantiate(dentry, inode);
 370         newdentry = NULL;
 371 out_dput2:
 372         dput(upper);
 373 out_dput:
 374         dput(newdentry);
 375 out_unlock:
 376         unlock_rename(workdir, upperdir);
 377 out:
 378         return err;
 379
 380 out_cleanup:
 381         ovl_cleanup(wdir, newdentry);
 382         goto out_dput2;
 383 }
 384
 385 static int ovl_create_or_link(struct dentry *dentry, int mode, dev_t rdev,
 386                               const char *link, struct dentry *hardlink)
 387 {
 388         int err;
 389         struct inode *inode;
 390         struct kstat stat = {
 391                 .mode = mode,
 392                 .rdev = rdev,
 393         };
 394
 395         err = -ENOMEM;
 396         inode = ovl_new_inode(dentry->d_sb, mode, dentry->d_fsdata);
 397         if (!inode)
 398                 goto out;
 399
 400         err = ovl_copy_up(dentry->d_parent);
 401         if (err)
 402                 goto out_iput;
 403
 404         if (!ovl_dentry_is_opaque(dentry)) {
 405                 err = ovl_create_upper(dentry, inode, &stat, link, hardlink);
 406         } else {
 407                 const struct cred *old_cred;
 408                 struct cred *override_cred;
 409
 410                 old_cred = ovl_override_creds(dentry->d_sb);
 411
 412                 err = -ENOMEM;
 413                 override_cred = prepare_creds();
 414                 if (override_cred) {
 415                         override_cred->fsuid = old_cred->fsuid;
 416                         override_cred->fsgid = old_cred->fsgid;
 417                         put_cred(override_creds(override_cred));
 418                         put_cred(override_cred);
 419
 420                         err = ovl_create_over_whiteout(dentry, inode, &stat,
 421                                                        link, hardlink);
 422                 }
 423                 revert_creds(old_cred);
 424         }
 425
 426         if (!err)
 427                 inode = NULL;
 428 out_iput:
 429         iput(inode);
 430 out:
 431         return err;
 432 }
 433
 434 static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
 435                              const char *link)
 436 {
 437         int err;
 438
 439         err = ovl_want_write(dentry);
 440         if (!err) {
 441                 err = ovl_create_or_link(dentry, mode, rdev, link, NULL);
 442                 ovl_drop_write(dentry);
 443         }
 444
 445         return err;
 446 }
 447
 448 static int ovl_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 449                       bool excl)
 450 {
 451         return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL);
 452 }
 453
 454 static int ovl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 455 {
 456         return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL);
 457 }
 458
 459 static int ovl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
 460                      dev_t rdev)
 461 {
 462         /* Don't allow creation of "whiteout" on overlay */
 463         if (S_ISCHR(mode) && rdev == WHITEOUT_DEV)
 464                 return -EPERM;
 465
 466         return ovl_create_object(dentry, mode, rdev, NULL);
 467 }
 468
 469 static int ovl_symlink(struct inode *dir, struct dentry *dentry,
 470                        const char *link)
 471 {
 472         return ovl_create_object(dentry, S_IFLNK, 0, link);
 473 }
 474
 475 static int ovl_link(struct dentry *old, struct inode *newdir,
 476                     struct dentry *new)
 477 {
 478         int err;
 479         struct dentry *upper;
 480
 481         err = ovl_want_write(old);
 482         if (err)
 483                 goto out;
 484
 485         err = ovl_copy_up(old);
 486         if (err)
 487                 goto out_drop_write;
 488
 489         upper = ovl_dentry_upper(old);
 490         err = ovl_create_or_link(new, upper->d_inode->i_mode, 0, NULL, upper);
 491
 492 out_drop_write:
 493         ovl_drop_write(old);
 494 out:
 495         return err;
 496 }
 497
 498 static int ovl_remove_and_whiteout(struct dentry *dentry, bool is_dir)
 499 {
 500         struct dentry *workdir = ovl_workdir(dentry);
 501         struct inode *wdir = workdir->d_inode;
 502         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 503         struct inode *udir = upperdir->d_inode;
 504         struct dentry *whiteout;
 505         struct dentry *upper;
 506         struct dentry *opaquedir = NULL;
 507         int err;
 508
 509         if (WARN_ON(!workdir))
 510                 return -EROFS;
 511
 512         if (is_dir) {
 513                 if (OVL_TYPE_MERGE_OR_LOWER(ovl_path_type(dentry))) {
 514                         opaquedir = ovl_check_empty_and_clear(dentry);
 515                         err = PTR_ERR(opaquedir);
 516                         if (IS_ERR(opaquedir))
 517                                 goto out;
 518                 } else {
 519                         LIST_HEAD(list);
 520
 521                         /*
 522                          * When removing an empty opaque directory, then it
 523                          * makes no sense to replace it with an exact replica of
 524                          * itself.  But emptiness still needs to be checked.
 525                          */
 526                         err = ovl_check_empty_dir(dentry, &list);
 527                         ovl_cache_free(&list);
 528                         if (err)
 529                                 goto out;
 530                 }
 531         }
 532
 533         err = ovl_lock_rename_workdir(workdir, upperdir);
 534         if (err)
 535                 goto out_dput;
 536
 537         whiteout = ovl_whiteout(workdir, dentry);
 538         err = PTR_ERR(whiteout);
 539         if (IS_ERR(whiteout))
 540                 goto out_unlock;
 541
 542         upper = ovl_dentry_upper(dentry);
 543         if (!upper) {
 544                 upper = lookup_one_len(dentry->d_name.name, upperdir,
 545                                        dentry->d_name.len);
 546                 err = PTR_ERR(upper);
 547                 if (IS_ERR(upper))
 548                         goto kill_whiteout;
 549
 550                 err = ovl_do_rename(wdir, whiteout, udir, upper, 0);
 551                 dput(upper);
 552                 if (err)
 553                         goto kill_whiteout;
 554         } else {
 555                 int flags = 0;
 556
 557                 if (opaquedir)
 558                         upper = opaquedir;
 559                 err = -ESTALE;
 560                 if (upper->d_parent != upperdir)
 561                         goto kill_whiteout;
 562
 563                 if (is_dir)
 564                         flags |= RENAME_EXCHANGE;
 565
 566                 err = ovl_do_rename(wdir, whiteout, udir, upper, flags);
 567                 if (err)
 568                         goto kill_whiteout;
 569
 570                 if (is_dir)
 571                         ovl_cleanup(wdir, upper);
 572         }
 573         ovl_dentry_version_inc(dentry->d_parent);
 574 out_d_drop:
 575         d_drop(dentry);
 576         dput(whiteout);
 577 out_unlock:
 578         unlock_rename(workdir, upperdir);
 579 out_dput:
 580         dput(opaquedir);
 581 out:
 582         return err;
 583
 584 kill_whiteout:
 585         ovl_cleanup(wdir, whiteout);
 586         goto out_d_drop;
 587 }
 588
 589 static int ovl_remove_upper(struct dentry *dentry, bool is_dir)
 590 {
 591         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 592         struct inode *dir = upperdir->d_inode;
 593         struct dentry *upper;
 594         int err;
 595
 596         inode_lock_nested(dir, I_MUTEX_PARENT);
 597         upper = lookup_one_len(dentry->d_name.name, upperdir,
 598                                dentry->d_name.len);
 599         err = PTR_ERR(upper);
 600         if (IS_ERR(upper))
 601                 goto out_unlock;
 602
 603         err = -ESTALE;
 604         if (upper == ovl_dentry_upper(dentry)) {
 605                 if (is_dir)
 606                         err = vfs_rmdir(dir, upper);
 607                 else
 608                         err = vfs_unlink(dir, upper, NULL);
 609                 ovl_dentry_version_inc(dentry->d_parent);
 610         }
 611         dput(upper);
 612
 613         /*
 614          * Keeping this dentry hashed would mean having to release
 615          * upperpath/lowerpath, which could only be done if we are the
 616          * sole user of this dentry.  Too tricky...  Just unhash for
 617          * now.
 618          */
 619         if (!err)
 620                 d_drop(dentry);
 621 out_unlock:
 622         inode_unlock(dir);
 623
 624         return err;
 625 }
 626
 627 static inline int ovl_check_sticky(struct dentry *dentry)
 628 {
 629         struct inode *dir = ovl_dentry_real(dentry->d_parent)->d_inode;
 630         struct inode *inode = ovl_dentry_real(dentry)->d_inode;
 631
 632         if (check_sticky(dir, inode))
 633                 return -EPERM;
 634
 635         return 0;
 636 }
 637
 638 static int ovl_do_remove(struct dentry *dentry, bool is_dir)
 639 {
 640         enum ovl_path_type type;
 641         int err;
 642
 643         err = ovl_check_sticky(dentry);
 644         if (err)
 645                 goto out;
 646
 647         err = ovl_want_write(dentry);
 648         if (err)
 649                 goto out;
 650
 651         err = ovl_copy_up(dentry->d_parent);
 652         if (err)
 653                 goto out_drop_write;
 654
 655         type = ovl_path_type(dentry);
 656         if (OVL_TYPE_PURE_UPPER(type)) {
 657                 err = ovl_remove_upper(dentry, is_dir);
 658         } else {
 659                 const struct cred *old_cred = ovl_override_creds(dentry->d_sb);
 660
 661                 err = ovl_remove_and_whiteout(dentry, is_dir);
 662
 663                 revert_creds(old_cred);
 664         }
 665 out_drop_write:
 666         ovl_drop_write(dentry);
 667 out:
 668         return err;
 669 }
 670
 671 static int ovl_unlink(struct inode *dir, struct dentry *dentry)
 672 {
 673         return ovl_do_remove(dentry, false);
 674 }
 675
 676 static int ovl_rmdir(struct inode *dir, struct dentry *dentry)
 677 {
 678         return ovl_do_remove(dentry, true);
 679 }
 680
 681 static int ovl_rename2(struct inode *olddir, struct dentry *old,
 682                        struct inode *newdir, struct dentry *new,
 683                        unsigned int flags)
 684 {
 685         int err;
 686         enum ovl_path_type old_type;
 687         enum ovl_path_type new_type;
 688         struct dentry *old_upperdir;
 689         struct dentry *new_upperdir;
 690         struct dentry *olddentry;
 691         struct dentry *newdentry;
 692         struct dentry *trap;
 693         bool old_opaque;
 694         bool new_opaque;
 695         bool cleanup_whiteout = false;
 696         bool overwrite = !(flags & RENAME_EXCHANGE);
 697         bool is_dir = d_is_dir(old);
 698         bool new_is_dir = false;
 699         struct dentry *opaquedir = NULL;
 700         const struct cred *old_cred = NULL;
 701
 702         err = -EINVAL;
 703         if (flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE))
 704                 goto out;
 705
 706         flags &= ~RENAME_NOREPLACE;
 707
 708         err = ovl_check_sticky(old);
 709         if (err)
 710                 goto out;
 711
 712         /* Don't copy up directory trees */
 713         old_type = ovl_path_type(old);
 714         err = -EXDEV;
 715         if (OVL_TYPE_MERGE_OR_LOWER(old_type) && is_dir)
 716                 goto out;
 717
 718         if (new->d_inode) {
 719                 err = ovl_check_sticky(new);
 720                 if (err)
 721                         goto out;
 722
 723                 if (d_is_dir(new))
 724                         new_is_dir = true;
 725
 726                 new_type = ovl_path_type(new);
 727                 err = -EXDEV;
 728                 if (!overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir)
 729                         goto out;
 730
 731                 err = 0;
 732                 if (!OVL_TYPE_UPPER(new_type) && !OVL_TYPE_UPPER(old_type)) {
 733                         if (ovl_dentry_lower(old)->d_inode ==
 734                             ovl_dentry_lower(new)->d_inode)
 735                                 goto out;
 736                 }
 737                 if (OVL_TYPE_UPPER(new_type) && OVL_TYPE_UPPER(old_type)) {
 738                         if (ovl_dentry_upper(old)->d_inode ==
 739                             ovl_dentry_upper(new)->d_inode)
 740                                 goto out;
 741                 }
 742         } else {
 743                 if (ovl_dentry_is_opaque(new))
 744                         new_type = __OVL_PATH_UPPER;
 745                 else
 746                         new_type = __OVL_PATH_UPPER | __OVL_PATH_PURE;
 747         }
 748
 749         err = ovl_want_write(old);
 750         if (err)
 751                 goto out;
 752
 753         err = ovl_copy_up(old);
 754         if (err)
 755                 goto out_drop_write;
 756
 757         err = ovl_copy_up(new->d_parent);
 758         if (err)
 759                 goto out_drop_write;
 760         if (!overwrite) {
 761                 err = ovl_copy_up(new);
 762                 if (err)
 763                         goto out_drop_write;
 764         }
 765
 766         old_opaque = !OVL_TYPE_PURE_UPPER(old_type);
 767         new_opaque = !OVL_TYPE_PURE_UPPER(new_type);
 768
 769         if (old_opaque || new_opaque)
 770                 old_cred = ovl_override_creds(old->d_sb);
 771
 772         if (overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir) {
 773                 opaquedir = ovl_check_empty_and_clear(new);
 774                 err = PTR_ERR(opaquedir);
 775                 if (IS_ERR(opaquedir)) {
 776                         opaquedir = NULL;
 777                         goto out_revert_creds;
 778                 }
 779         }
 780
 781         if (overwrite) {
 782                 if (old_opaque) {
 783                         if (new->d_inode || !new_opaque) {
 784                                 /* Whiteout source */
 785                                 flags |= RENAME_WHITEOUT;
 786                         } else {
 787                                 /* Switch whiteouts */
 788                                 flags |= RENAME_EXCHANGE;
 789                         }
 790                 } else if (is_dir && !new->d_inode && new_opaque) {
 791                         flags |= RENAME_EXCHANGE;
 792                         cleanup_whiteout = true;
 793                 }
 794         }
 795
 796         old_upperdir = ovl_dentry_upper(old->d_parent);
 797         new_upperdir = ovl_dentry_upper(new->d_parent);
 798
 799         trap = lock_rename(new_upperdir, old_upperdir);
 800
 801
 802         olddentry = lookup_one_len(old->d_name.name, old_upperdir,
 803                                    old->d_name.len);
 804         err = PTR_ERR(olddentry);
 805         if (IS_ERR(olddentry))
 806                 goto out_unlock;
 807
 808         err = -ESTALE;
 809         if (olddentry != ovl_dentry_upper(old))
 810                 goto out_dput_old;
 811
 812         newdentry = lookup_one_len(new->d_name.name, new_upperdir,
 813                                    new->d_name.len);
 814         err = PTR_ERR(newdentry);
 815         if (IS_ERR(newdentry))
 816                 goto out_dput_old;
 817
 818         err = -ESTALE;
 819         if (ovl_dentry_upper(new)) {
 820                 if (opaquedir) {
 821                         if (newdentry != opaquedir)
 822                                 goto out_dput;
 823                 } else {
 824                         if (newdentry != ovl_dentry_upper(new))
 825                                 goto out_dput;
 826                 }
 827         } else {
 828                 if (!d_is_negative(newdentry) &&
 829                     (!new_opaque || !ovl_is_whiteout(newdentry)))
 830                         goto out_dput;
 831         }
 832
 833         if (olddentry == trap)
 834                 goto out_dput;
 835         if (newdentry == trap)
 836                 goto out_dput;
 837
 838         if (is_dir && !old_opaque && new_opaque) {
 839                 err = ovl_set_opaque(olddentry);
 840                 if (err)
 841                         goto out_dput;
 842         }
 843         if (!overwrite && new_is_dir && old_opaque && !new_opaque) {
 844                 err = ovl_set_opaque(newdentry);
 845                 if (err)
 846                         goto out_dput;
 847         }
 848
 849         if (old_opaque || new_opaque) {
 850                 err = ovl_do_rename(old_upperdir->d_inode, olddentry,
 851                                     new_upperdir->d_inode, newdentry,
 852                                     flags);
 853         } else {
 854                 /* No debug for the plain case */
 855                 BUG_ON(flags & ~RENAME_EXCHANGE);
 856                 err = vfs_rename(old_upperdir->d_inode, olddentry,
 857                                  new_upperdir->d_inode, newdentry,
 858                                  NULL, flags);
 859         }
 860
 861         if (err) {
 862                 if (is_dir && !old_opaque && new_opaque)
 863                         ovl_remove_opaque(olddentry);
 864                 if (!overwrite && new_is_dir && old_opaque && !new_opaque)
 865                         ovl_remove_opaque(newdentry);
 866                 goto out_dput;
 867         }
 868
 869         if (is_dir && old_opaque && !new_opaque)
 870                 ovl_remove_opaque(olddentry);
 871         if (!overwrite && new_is_dir && !old_opaque && new_opaque)
 872                 ovl_remove_opaque(newdentry);
 873
 874         /*
 875          * Old dentry now lives in different location. Dentries in
 876          * lowerstack are stale. We cannot drop them here because
 877          * access to them is lockless. This could be only pure upper
 878          * or opaque directory - numlower is zero. Or upper non-dir
 879          * entry - its pureness is tracked by flag opaque.
 880          */
 881         if (old_opaque != new_opaque) {
 882                 ovl_dentry_set_opaque(old, new_opaque);
 883                 if (!overwrite)
 884                         ovl_dentry_set_opaque(new, old_opaque);
 885         }
 886
 887         if (cleanup_whiteout)
 888                 ovl_cleanup(old_upperdir->d_inode, newdentry);
 889
 890         ovl_dentry_version_inc(old->d_parent);
 891         ovl_dentry_version_inc(new->d_parent);
 892
 893 out_dput:
 894         dput(newdentry);
 895 out_dput_old:
 896         dput(olddentry);
 897 out_unlock:
 898         unlock_rename(new_upperdir, old_upperdir);
 899 out_revert_creds:
 900         if (old_opaque || new_opaque)
 901                 revert_creds(old_cred);
 902 out_drop_write:
 903         ovl_drop_write(old);
 904 out:
 905         dput(opaquedir);
 906         return err;
 907 }
 908
 909 const struct inode_operations ovl_dir_inode_operations = {
 910         .lookup         = ovl_lookup,
 911         .mkdir          = ovl_mkdir,
 912         .symlink        = ovl_symlink,
 913         .unlink         = ovl_unlink,
 914         .rmdir          = ovl_rmdir,
 915         .rename2        = ovl_rename2,
 916         .link           = ovl_link,
 917         .setattr        = ovl_setattr,
 918         .create         = ovl_create,
 919         .mknod          = ovl_mknod,
 920         .permission     = ovl_permission,
 921         .getattr        = ovl_dir_getattr,
 922         .setxattr       = ovl_setxattr,
 923         .getxattr       = ovl_getxattr,
 924         .listxattr      = ovl_listxattr,
 925         .removexattr    = ovl_removexattr,
 926 };