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