fs/overlayfs/dir.c

   1 /*
   2  *
   3  * Copyright (C) 2011 Novell Inc.
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 as published by
   7  * the Free Software Foundation.
   8  */
   9
  10 #include <linux/fs.h>
  11 #include <linux/namei.h>
  12 #include <linux/xattr.h>
  13 #include <linux/security.h>
  14 #include <linux/cred.h>
  15 #include "overlayfs.h"
  16
  17 void ovl_cleanup(struct inode *wdir, struct dentry *wdentry)
  18 {
  19         int err;
  20
  21         dget(wdentry);
  22         if (d_is_dir(wdentry))
  23                 err = ovl_do_rmdir(wdir, wdentry);
  24         else
  25                 err = ovl_do_unlink(wdir, wdentry);
  26         dput(wdentry);
  27
  28         if (err) {
  29                 pr_err("overlayfs: cleanup of '%pd2' failed (%i)\n",
  30                        wdentry, err);
  31         }
  32 }
  33
  34 struct dentry *ovl_lookup_temp(struct dentry *workdir, struct dentry *dentry)
  35 {
  36         struct dentry *temp;
  37         char name[20];
  38
  39         snprintf(name, sizeof(name), "#%lx", (unsigned long) dentry);
  40
  41         temp = lookup_one_len(name, workdir, strlen(name));
  42         if (!IS_ERR(temp) && temp->d_inode) {
  43                 pr_err("overlayfs: workdir/%s already exists\n", name);
  44                 dput(temp);
  45                 temp = ERR_PTR(-EIO);
  46         }
  47
  48         return temp;
  49 }
  50
  51 /* caller holds i_mutex on workdir */
  52 static struct dentry *ovl_whiteout(struct dentry *workdir,
  53                                    struct dentry *dentry)
  54 {
  55         int err;
  56         struct dentry *whiteout;
  57         struct inode *wdir = workdir->d_inode;
  58
  59         whiteout = ovl_lookup_temp(workdir, dentry);
  60         if (IS_ERR(whiteout))
  61                 return whiteout;
  62
  63         err = ovl_do_whiteout(wdir, whiteout);
  64         if (err) {
  65                 dput(whiteout);
  66                 whiteout = ERR_PTR(err);
  67         }
  68
  69         return whiteout;
  70 }
  71
  72 int ovl_create_real(struct inode *dir, struct dentry *newdentry,
  73                     struct kstat *stat, const char *link,
  74                     struct dentry *hardlink, bool debug)
  75 {
  76         int err;
  77
  78         if (newdentry->d_inode)
  79                 return -ESTALE;
  80
  81         if (hardlink) {
  82                 err = ovl_do_link(hardlink, dir, newdentry, debug);
  83         } else {
  84                 switch (stat->mode & S_IFMT) {
  85                 case S_IFREG:
  86                         err = ovl_do_create(dir, newdentry, stat->mode, debug);
  87                         break;
  88
  89                 case S_IFDIR:
  90                         err = ovl_do_mkdir(dir, newdentry, stat->mode, debug);
  91                         break;
  92
  93                 case S_IFCHR:
  94                 case S_IFBLK:
  95                 case S_IFIFO:
  96                 case S_IFSOCK:
  97                         err = ovl_do_mknod(dir, newdentry,
  98                                            stat->mode, stat->rdev, debug);
  99                         break;
 100
 101                 case S_IFLNK:
 102                         err = ovl_do_symlink(dir, newdentry, link, debug);
 103                         break;
 104
 105                 default:
 106                         err = -EPERM;
 107                 }
 108         }
 109         if (!err && WARN_ON(!newdentry->d_inode)) {
 110                 /*
 111                  * Not quite sure if non-instantiated dentry is legal or not.
 112                  * VFS doesn't seem to care so check and warn here.
 113                  */
 114                 err = -ENOENT;
 115         }
 116         return err;
 117 }
 118
 119 static int ovl_set_opaque(struct dentry *upperdentry)
 120 {
 121         return ovl_do_setxattr(upperdentry, OVL_XATTR_OPAQUE, "y", 1, 0);
 122 }
 123
 124 static void ovl_remove_opaque(struct dentry *upperdentry)
 125 {
 126         int err;
 127
 128         err = ovl_do_removexattr(upperdentry, OVL_XATTR_OPAQUE);
 129         if (err) {
 130                 pr_warn("overlayfs: failed to remove opaque from '%s' (%i)\n",
 131                         upperdentry->d_name.name, err);
 132         }
 133 }
 134
 135 static int ovl_dir_getattr(struct vfsmount *mnt, struct dentry *dentry,
 136                          struct kstat *stat)
 137 {
 138         int err;
 139         enum ovl_path_type type;
 140         struct path realpath;
 141         const struct cred *old_cred;
 142
 143         type = ovl_path_real(dentry, &realpath);
 144         old_cred = ovl_override_creds(dentry->d_sb);
 145         err = vfs_getattr(&realpath, stat);
 146         revert_creds(old_cred);
 147         if (err)
 148                 return err;
 149
 150         stat->dev = dentry->d_sb->s_dev;
 151         stat->ino = dentry->d_inode->i_ino;
 152
 153         /*
 154          * It's probably not worth it to count subdirs to get the
 155          * correct link count.  nlink=1 seems to pacify 'find' and
 156          * other utilities.
 157          */
 158         if (OVL_TYPE_MERGE(type))
 159                 stat->nlink = 1;
 160
 161         return 0;
 162 }
 163
 164 /* Common operations required to be done after creation of file on upper */
 165 static void ovl_instantiate(struct dentry *dentry, struct inode *inode,
 166                             struct dentry *newdentry, bool hardlink)
 167 {
 168         ovl_dentry_version_inc(dentry->d_parent);
 169         ovl_dentry_update(dentry, newdentry);
 170         if (!hardlink) {
 171                 ovl_inode_update(inode, d_inode(newdentry));
 172                 ovl_copyattr(newdentry->d_inode, inode);
 173         } else {
 174                 WARN_ON(ovl_inode_real(inode, NULL) != d_inode(newdentry));
 175                 inc_nlink(inode);
 176         }
 177         d_instantiate(dentry, inode);
 178 }
 179
 180 static int ovl_create_upper(struct dentry *dentry, struct inode *inode,
 181                             struct kstat *stat, const char *link,
 182                             struct dentry *hardlink)
 183 {
 184         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 185         struct inode *udir = upperdir->d_inode;
 186         struct dentry *newdentry;
 187         int err;
 188
 189         inode_lock_nested(udir, I_MUTEX_PARENT);
 190         newdentry = lookup_one_len(dentry->d_name.name, upperdir,
 191                                    dentry->d_name.len);
 192         err = PTR_ERR(newdentry);
 193         if (IS_ERR(newdentry))
 194                 goto out_unlock;
 195         err = ovl_create_real(udir, newdentry, stat, link, hardlink, false);
 196         if (err)
 197                 goto out_dput;
 198
 199         ovl_instantiate(dentry, inode, newdentry, !!hardlink);
 200         newdentry = NULL;
 201 out_dput:
 202         dput(newdentry);
 203 out_unlock:
 204         inode_unlock(udir);
 205         return err;
 206 }
 207
 208 static int ovl_lock_rename_workdir(struct dentry *workdir,
 209                                    struct dentry *upperdir)
 210 {
 211         /* Workdir should not be the same as upperdir */
 212         if (workdir == upperdir)
 213                 goto err;
 214
 215         /* Workdir should not be subdir of upperdir and vice versa */
 216         if (lock_rename(workdir, upperdir) != NULL)
 217                 goto err_unlock;
 218
 219         return 0;
 220
 221 err_unlock:
 222         unlock_rename(workdir, upperdir);
 223 err:
 224         pr_err("overlayfs: failed to lock workdir+upperdir\n");
 225         return -EIO;
 226 }
 227
 228 static struct dentry *ovl_clear_empty(struct dentry *dentry,
 229                                       struct list_head *list)
 230 {
 231         struct dentry *workdir = ovl_workdir(dentry);
 232         struct inode *wdir = workdir->d_inode;
 233         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 234         struct inode *udir = upperdir->d_inode;
 235         struct path upperpath;
 236         struct dentry *upper;
 237         struct dentry *opaquedir;
 238         struct kstat stat;
 239         int err;
 240
 241         if (WARN_ON(!workdir))
 242                 return ERR_PTR(-EROFS);
 243
 244         err = ovl_lock_rename_workdir(workdir, upperdir);
 245         if (err)
 246                 goto out;
 247
 248         ovl_path_upper(dentry, &upperpath);
 249         err = vfs_getattr(&upperpath, &stat);
 250         if (err)
 251                 goto out_unlock;
 252
 253         err = -ESTALE;
 254         if (!S_ISDIR(stat.mode))
 255                 goto out_unlock;
 256         upper = upperpath.dentry;
 257         if (upper->d_parent->d_inode != udir)
 258                 goto out_unlock;
 259
 260         opaquedir = ovl_lookup_temp(workdir, dentry);
 261         err = PTR_ERR(opaquedir);
 262         if (IS_ERR(opaquedir))
 263                 goto out_unlock;
 264
 265         err = ovl_create_real(wdir, opaquedir, &stat, NULL, NULL, true);
 266         if (err)
 267                 goto out_dput;
 268
 269         err = ovl_copy_xattr(upper, opaquedir);
 270         if (err)
 271                 goto out_cleanup;
 272
 273         err = ovl_set_opaque(opaquedir);
 274         if (err)
 275                 goto out_cleanup;
 276
 277         inode_lock(opaquedir->d_inode);
 278         err = ovl_set_attr(opaquedir, &stat);
 279         inode_unlock(opaquedir->d_inode);
 280         if (err)
 281                 goto out_cleanup;
 282
 283         err = ovl_do_rename(wdir, opaquedir, udir, upper, RENAME_EXCHANGE);
 284         if (err)
 285                 goto out_cleanup;
 286
 287         ovl_cleanup_whiteouts(upper, list);
 288         ovl_cleanup(wdir, upper);
 289         unlock_rename(workdir, upperdir);
 290
 291         /* dentry's upper doesn't match now, get rid of it */
 292         d_drop(dentry);
 293
 294         return opaquedir;
 295
 296 out_cleanup:
 297         ovl_cleanup(wdir, opaquedir);
 298 out_dput:
 299         dput(opaquedir);
 300 out_unlock:
 301         unlock_rename(workdir, upperdir);
 302 out:
 303         return ERR_PTR(err);
 304 }
 305
 306 static struct dentry *ovl_check_empty_and_clear(struct dentry *dentry)
 307 {
 308         int err;
 309         struct dentry *ret = NULL;
 310         enum ovl_path_type type = ovl_path_type(dentry);
 311         LIST_HEAD(list);
 312
 313         err = ovl_check_empty_dir(dentry, &list);
 314         if (err) {
 315                 ret = ERR_PTR(err);
 316                 goto out_free;
 317         }
 318
 319         /*
 320          * When removing an empty opaque directory, then it makes no sense to
 321          * replace it with an exact replica of itself.
 322          *
 323          * If no upperdentry then skip clearing whiteouts.
 324          *
 325          * Can race with copy-up, since we don't hold the upperdir mutex.
 326          * Doesn't matter, since copy-up can't create a non-empty directory
 327          * from an empty one.
 328          */
 329         if (OVL_TYPE_UPPER(type) && OVL_TYPE_MERGE(type))
 330                 ret = ovl_clear_empty(dentry, &list);
 331
 332 out_free:
 333         ovl_cache_free(&list);
 334
 335         return ret;
 336 }
 337
 338 static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
 339                                     struct kstat *stat, const char *link,
 340                                     struct dentry *hardlink)
 341 {
 342         struct dentry *workdir = ovl_workdir(dentry);
 343         struct inode *wdir = workdir->d_inode;
 344         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 345         struct inode *udir = upperdir->d_inode;
 346         struct dentry *upper;
 347         struct dentry *newdentry;
 348         int err;
 349
 350         if (WARN_ON(!workdir))
 351                 return -EROFS;
 352
 353         err = ovl_lock_rename_workdir(workdir, upperdir);
 354         if (err)
 355                 goto out;
 356
 357         newdentry = ovl_lookup_temp(workdir, dentry);
 358         err = PTR_ERR(newdentry);
 359         if (IS_ERR(newdentry))
 360                 goto out_unlock;
 361
 362         upper = lookup_one_len(dentry->d_name.name, upperdir,
 363                                dentry->d_name.len);
 364         err = PTR_ERR(upper);
 365         if (IS_ERR(upper))
 366                 goto out_dput;
 367
 368         err = ovl_create_real(wdir, newdentry, stat, link, hardlink, true);
 369         if (err)
 370                 goto out_dput2;
 371
 372         /*
 373          * mode could have been mutilated due to umask (e.g. sgid directory)
 374          */
 375         if (!hardlink &&
 376             !S_ISLNK(stat->mode) && newdentry->d_inode->i_mode != stat->mode) {
 377                 struct iattr attr = {
 378                         .ia_valid = ATTR_MODE,
 379                         .ia_mode = stat->mode,
 380                 };
 381                 inode_lock(newdentry->d_inode);
 382                 err = notify_change(newdentry, &attr, NULL);
 383                 inode_unlock(newdentry->d_inode);
 384                 if (err)
 385                         goto out_cleanup;
 386         }
 387
 388         if (!hardlink && S_ISDIR(stat->mode)) {
 389                 err = ovl_set_opaque(newdentry);
 390                 if (err)
 391                         goto out_cleanup;
 392
 393                 err = ovl_do_rename(wdir, newdentry, udir, upper,
 394                                     RENAME_EXCHANGE);
 395                 if (err)
 396                         goto out_cleanup;
 397
 398                 ovl_cleanup(wdir, upper);
 399         } else {
 400                 err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
 401                 if (err)
 402                         goto out_cleanup;
 403         }
 404         ovl_instantiate(dentry, inode, newdentry, !!hardlink);
 405         newdentry = NULL;
 406 out_dput2:
 407         dput(upper);
 408 out_dput:
 409         dput(newdentry);
 410 out_unlock:
 411         unlock_rename(workdir, upperdir);
 412 out:
 413         return err;
 414
 415 out_cleanup:
 416         ovl_cleanup(wdir, newdentry);
 417         goto out_dput2;
 418 }
 419
 420 static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
 421                               struct kstat *stat, const char *link,
 422                               struct dentry *hardlink)
 423 {
 424         int err;
 425         const struct cred *old_cred;
 426         struct cred *override_cred;
 427
 428         err = ovl_copy_up(dentry->d_parent);
 429         if (err)
 430                 return err;
 431
 432         old_cred = ovl_override_creds(dentry->d_sb);
 433         err = -ENOMEM;
 434         override_cred = prepare_creds();
 435         if (override_cred) {
 436                 override_cred->fsuid = inode->i_uid;
 437                 override_cred->fsgid = inode->i_gid;
 438                 put_cred(override_creds(override_cred));
 439                 put_cred(override_cred);
 440
 441                 if (!ovl_dentry_is_opaque(dentry))
 442                         err = ovl_create_upper(dentry, inode, stat, link,
 443                                                 hardlink);
 444                 else
 445                         err = ovl_create_over_whiteout(dentry, inode, stat,
 446                                                         link, hardlink);
 447         }
 448         revert_creds(old_cred);
 449         if (!err) {
 450                 struct inode *realinode = d_inode(ovl_dentry_upper(dentry));
 451
 452                 WARN_ON(inode->i_mode != realinode->i_mode);
 453                 WARN_ON(!uid_eq(inode->i_uid, realinode->i_uid));
 454                 WARN_ON(!gid_eq(inode->i_gid, realinode->i_gid));
 455         }
 456         return err;
 457 }
 458
 459 static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
 460                              const char *link)
 461 {
 462         int err;
 463         struct inode *inode;
 464         struct kstat stat = {
 465                 .rdev = rdev,
 466         };
 467
 468         err = ovl_want_write(dentry);
 469         if (err)
 470                 goto out;
 471
 472         err = -ENOMEM;
 473         inode = ovl_new_inode(dentry->d_sb, mode);
 474         if (!inode)
 475                 goto out_drop_write;
 476
 477         inode_init_owner(inode, dentry->d_parent->d_inode, mode);
 478         stat.mode = inode->i_mode;
 479
 480         err = ovl_create_or_link(dentry, inode, &stat, link, NULL);
 481         if (err)
 482                 iput(inode);
 483
 484 out_drop_write:
 485         ovl_drop_write(dentry);
 486 out:
 487         return err;
 488 }
 489
 490 static int ovl_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 491                       bool excl)
 492 {
 493         return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL);
 494 }
 495
 496 static int ovl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 497 {
 498         return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL);
 499 }
 500
 501 static int ovl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
 502                      dev_t rdev)
 503 {
 504         /* Don't allow creation of "whiteout" on overlay */
 505         if (S_ISCHR(mode) && rdev == WHITEOUT_DEV)
 506                 return -EPERM;
 507
 508         return ovl_create_object(dentry, mode, rdev, NULL);
 509 }
 510
 511 static int ovl_symlink(struct inode *dir, struct dentry *dentry,
 512                        const char *link)
 513 {
 514         return ovl_create_object(dentry, S_IFLNK, 0, link);
 515 }
 516
 517 static int ovl_link(struct dentry *old, struct inode *newdir,
 518                     struct dentry *new)
 519 {
 520         int err;
 521         struct inode *inode;
 522
 523         err = ovl_want_write(old);
 524         if (err)
 525                 goto out;
 526
 527         err = ovl_copy_up(old);
 528         if (err)
 529                 goto out_drop_write;
 530
 531         inode = d_inode(old);
 532         ihold(inode);
 533
 534         err = ovl_create_or_link(new, inode, NULL, NULL, ovl_dentry_upper(old));
 535         if (err)
 536                 iput(inode);
 537
 538 out_drop_write:
 539         ovl_drop_write(old);
 540 out:
 541         return err;
 542 }
 543
 544 static int ovl_remove_and_whiteout(struct dentry *dentry, bool is_dir)
 545 {
 546         struct dentry *workdir = ovl_workdir(dentry);
 547         struct inode *wdir = workdir->d_inode;
 548         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 549         struct inode *udir = upperdir->d_inode;
 550         struct dentry *whiteout;
 551         struct dentry *upper;
 552         struct dentry *opaquedir = NULL;
 553         int err;
 554         int flags = 0;
 555
 556         if (WARN_ON(!workdir))
 557                 return -EROFS;
 558
 559         if (is_dir) {
 560                 opaquedir = ovl_check_empty_and_clear(dentry);
 561                 err = PTR_ERR(opaquedir);
 562                 if (IS_ERR(opaquedir))
 563                         goto out;
 564         }
 565
 566         err = ovl_lock_rename_workdir(workdir, upperdir);
 567         if (err)
 568                 goto out_dput;
 569
 570         upper = lookup_one_len(dentry->d_name.name, upperdir,
 571                                dentry->d_name.len);
 572         err = PTR_ERR(upper);
 573         if (IS_ERR(upper))
 574                 goto out_unlock;
 575
 576         err = -ESTALE;
 577         if ((opaquedir && upper != opaquedir) ||
 578             (!opaquedir && ovl_dentry_upper(dentry) &&
 579              upper != ovl_dentry_upper(dentry))) {
 580                 goto out_dput_upper;
 581         }
 582
 583         whiteout = ovl_whiteout(workdir, dentry);
 584         err = PTR_ERR(whiteout);
 585         if (IS_ERR(whiteout))
 586                 goto out_dput_upper;
 587
 588         if (d_is_dir(upper))
 589                 flags = RENAME_EXCHANGE;
 590
 591         err = ovl_do_rename(wdir, whiteout, udir, upper, flags);
 592         if (err)
 593                 goto kill_whiteout;
 594         if (flags)
 595                 ovl_cleanup(wdir, upper);
 596
 597         ovl_dentry_version_inc(dentry->d_parent);
 598 out_d_drop:
 599         d_drop(dentry);
 600         dput(whiteout);
 601 out_dput_upper:
 602         dput(upper);
 603 out_unlock:
 604         unlock_rename(workdir, upperdir);
 605 out_dput:
 606         dput(opaquedir);
 607 out:
 608         return err;
 609
 610 kill_whiteout:
 611         ovl_cleanup(wdir, whiteout);
 612         goto out_d_drop;
 613 }
 614
 615 static int ovl_remove_upper(struct dentry *dentry, bool is_dir)
 616 {
 617         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 618         struct inode *dir = upperdir->d_inode;
 619         struct dentry *upper;
 620         int err;
 621
 622         inode_lock_nested(dir, I_MUTEX_PARENT);
 623         upper = lookup_one_len(dentry->d_name.name, upperdir,
 624                                dentry->d_name.len);
 625         err = PTR_ERR(upper);
 626         if (IS_ERR(upper))
 627                 goto out_unlock;
 628
 629         err = -ESTALE;
 630         if (upper == ovl_dentry_upper(dentry)) {
 631                 if (is_dir)
 632                         err = vfs_rmdir(dir, upper);
 633                 else
 634                         err = vfs_unlink(dir, upper, NULL);
 635                 ovl_dentry_version_inc(dentry->d_parent);
 636         }
 637         dput(upper);
 638
 639         /*
 640          * Keeping this dentry hashed would mean having to release
 641          * upperpath/lowerpath, which could only be done if we are the
 642          * sole user of this dentry.  Too tricky...  Just unhash for
 643          * now.
 644          */
 645         if (!err)
 646                 d_drop(dentry);
 647 out_unlock:
 648         inode_unlock(dir);
 649
 650         return err;
 651 }
 652
 653 static inline int ovl_check_sticky(struct dentry *dentry)
 654 {
 655         struct inode *dir = ovl_dentry_real(dentry->d_parent)->d_inode;
 656         struct inode *inode = ovl_dentry_real(dentry)->d_inode;
 657
 658         if (check_sticky(dir, inode))
 659                 return -EPERM;
 660
 661         return 0;
 662 }
 663
 664 static int ovl_do_remove(struct dentry *dentry, bool is_dir)
 665 {
 666         enum ovl_path_type type;
 667         int err;
 668         const struct cred *old_cred;
 669
 670
 671         err = ovl_check_sticky(dentry);
 672         if (err)
 673                 goto out;
 674
 675         err = ovl_want_write(dentry);
 676         if (err)
 677                 goto out;
 678
 679         err = ovl_copy_up(dentry->d_parent);
 680         if (err)
 681                 goto out_drop_write;
 682
 683         type = ovl_path_type(dentry);
 684
 685         old_cred = ovl_override_creds(dentry->d_sb);
 686         if (OVL_TYPE_PURE_UPPER(type))
 687                 err = ovl_remove_upper(dentry, is_dir);
 688         else
 689                 err = ovl_remove_and_whiteout(dentry, is_dir);
 690         revert_creds(old_cred);
 691         if (!err) {
 692                 if (is_dir)
 693                         clear_nlink(dentry->d_inode);
 694                 else
 695                         drop_nlink(dentry->d_inode);
 696         }
 697 out_drop_write:
 698         ovl_drop_write(dentry);
 699 out:
 700         return err;
 701 }
 702
 703 static int ovl_unlink(struct inode *dir, struct dentry *dentry)
 704 {
 705         return ovl_do_remove(dentry, false);
 706 }
 707
 708 static int ovl_rmdir(struct inode *dir, struct dentry *dentry)
 709 {
 710         return ovl_do_remove(dentry, true);
 711 }
 712
 713 static int ovl_rename2(struct inode *olddir, struct dentry *old,
 714                        struct inode *newdir, struct dentry *new,
 715                        unsigned int flags)
 716 {
 717         int err;
 718         enum ovl_path_type old_type;
 719         enum ovl_path_type new_type;
 720         struct dentry *old_upperdir;
 721         struct dentry *new_upperdir;
 722         struct dentry *olddentry;
 723         struct dentry *newdentry;
 724         struct dentry *trap;
 725         bool old_opaque;
 726         bool new_opaque;
 727         bool cleanup_whiteout = false;
 728         bool overwrite = !(flags & RENAME_EXCHANGE);
 729         bool is_dir = d_is_dir(old);
 730         bool new_is_dir = false;
 731         struct dentry *opaquedir = NULL;
 732         const struct cred *old_cred = NULL;
 733
 734         err = -EINVAL;
 735         if (flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE))
 736                 goto out;
 737
 738         flags &= ~RENAME_NOREPLACE;
 739
 740         err = ovl_check_sticky(old);
 741         if (err)
 742                 goto out;
 743
 744         /* Don't copy up directory trees */
 745         old_type = ovl_path_type(old);
 746         err = -EXDEV;
 747         if (OVL_TYPE_MERGE_OR_LOWER(old_type) && is_dir)
 748                 goto out;
 749
 750         if (new->d_inode) {
 751                 err = ovl_check_sticky(new);
 752                 if (err)
 753                         goto out;
 754
 755                 if (d_is_dir(new))
 756                         new_is_dir = true;
 757
 758                 new_type = ovl_path_type(new);
 759                 err = -EXDEV;
 760                 if (!overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir)
 761                         goto out;
 762
 763                 err = 0;
 764                 if (!OVL_TYPE_UPPER(new_type) && !OVL_TYPE_UPPER(old_type)) {
 765                         if (ovl_dentry_lower(old)->d_inode ==
 766                             ovl_dentry_lower(new)->d_inode)
 767                                 goto out;
 768                 }
 769                 if (OVL_TYPE_UPPER(new_type) && OVL_TYPE_UPPER(old_type)) {
 770                         if (ovl_dentry_upper(old)->d_inode ==
 771                             ovl_dentry_upper(new)->d_inode)
 772                                 goto out;
 773                 }
 774         } else {
 775                 if (ovl_dentry_is_opaque(new))
 776                         new_type = __OVL_PATH_UPPER;
 777                 else
 778                         new_type = __OVL_PATH_UPPER | __OVL_PATH_PURE;
 779         }
 780
 781         err = ovl_want_write(old);
 782         if (err)
 783                 goto out;
 784
 785         err = ovl_copy_up(old);
 786         if (err)
 787                 goto out_drop_write;
 788
 789         err = ovl_copy_up(new->d_parent);
 790         if (err)
 791                 goto out_drop_write;
 792         if (!overwrite) {
 793                 err = ovl_copy_up(new);
 794                 if (err)
 795                         goto out_drop_write;
 796         }
 797
 798         old_opaque = !OVL_TYPE_PURE_UPPER(old_type);
 799         new_opaque = !OVL_TYPE_PURE_UPPER(new_type);
 800
 801         old_cred = ovl_override_creds(old->d_sb);
 802
 803         if (overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir) {
 804                 opaquedir = ovl_check_empty_and_clear(new);
 805                 err = PTR_ERR(opaquedir);
 806                 if (IS_ERR(opaquedir)) {
 807                         opaquedir = NULL;
 808                         goto out_revert_creds;
 809                 }
 810         }
 811
 812         if (overwrite) {
 813                 if (old_opaque) {
 814                         if (new->d_inode || !new_opaque) {
 815                                 /* Whiteout source */
 816                                 flags |= RENAME_WHITEOUT;
 817                         } else {
 818                                 /* Switch whiteouts */
 819                                 flags |= RENAME_EXCHANGE;
 820                         }
 821                 } else if (is_dir && !new->d_inode && new_opaque) {
 822                         flags |= RENAME_EXCHANGE;
 823                         cleanup_whiteout = true;
 824                 }
 825         }
 826
 827         old_upperdir = ovl_dentry_upper(old->d_parent);
 828         new_upperdir = ovl_dentry_upper(new->d_parent);
 829
 830         trap = lock_rename(new_upperdir, old_upperdir);
 831
 832
 833         olddentry = lookup_one_len(old->d_name.name, old_upperdir,
 834                                    old->d_name.len);
 835         err = PTR_ERR(olddentry);
 836         if (IS_ERR(olddentry))
 837                 goto out_unlock;
 838
 839         err = -ESTALE;
 840         if (olddentry != ovl_dentry_upper(old))
 841                 goto out_dput_old;
 842
 843         newdentry = lookup_one_len(new->d_name.name, new_upperdir,
 844                                    new->d_name.len);
 845         err = PTR_ERR(newdentry);
 846         if (IS_ERR(newdentry))
 847                 goto out_dput_old;
 848
 849         err = -ESTALE;
 850         if (ovl_dentry_upper(new)) {
 851                 if (opaquedir) {
 852                         if (newdentry != opaquedir)
 853                                 goto out_dput;
 854                 } else {
 855                         if (newdentry != ovl_dentry_upper(new))
 856                                 goto out_dput;
 857                 }
 858         } else {
 859                 if (!d_is_negative(newdentry) &&
 860                     (!new_opaque || !ovl_is_whiteout(newdentry)))
 861                         goto out_dput;
 862         }
 863
 864         if (olddentry == trap)
 865                 goto out_dput;
 866         if (newdentry == trap)
 867                 goto out_dput;
 868
 869         if (is_dir && !old_opaque && new_opaque) {
 870                 err = ovl_set_opaque(olddentry);
 871                 if (err)
 872                         goto out_dput;
 873         }
 874         if (!overwrite && new_is_dir && old_opaque && !new_opaque) {
 875                 err = ovl_set_opaque(newdentry);
 876                 if (err)
 877                         goto out_dput;
 878         }
 879
 880         if (old_opaque || new_opaque) {
 881                 err = ovl_do_rename(old_upperdir->d_inode, olddentry,
 882                                     new_upperdir->d_inode, newdentry,
 883                                     flags);
 884         } else {
 885                 /* No debug for the plain case */
 886                 BUG_ON(flags & ~RENAME_EXCHANGE);
 887                 err = vfs_rename(old_upperdir->d_inode, olddentry,
 888                                  new_upperdir->d_inode, newdentry,
 889                                  NULL, flags);
 890         }
 891
 892         if (err) {
 893                 if (is_dir && !old_opaque && new_opaque)
 894                         ovl_remove_opaque(olddentry);
 895                 if (!overwrite && new_is_dir && old_opaque && !new_opaque)
 896                         ovl_remove_opaque(newdentry);
 897                 goto out_dput;
 898         }
 899
 900         if (is_dir && old_opaque && !new_opaque)
 901                 ovl_remove_opaque(olddentry);
 902         if (!overwrite && new_is_dir && !old_opaque && new_opaque)
 903                 ovl_remove_opaque(newdentry);
 904
 905         /*
 906          * Old dentry now lives in different location. Dentries in
 907          * lowerstack are stale. We cannot drop them here because
 908          * access to them is lockless. This could be only pure upper
 909          * or opaque directory - numlower is zero. Or upper non-dir
 910          * entry - its pureness is tracked by flag opaque.
 911          */
 912         if (old_opaque != new_opaque) {
 913                 ovl_dentry_set_opaque(old, new_opaque);
 914                 if (!overwrite)
 915                         ovl_dentry_set_opaque(new, old_opaque);
 916         }
 917
 918         if (cleanup_whiteout)
 919                 ovl_cleanup(old_upperdir->d_inode, newdentry);
 920
 921         ovl_dentry_version_inc(old->d_parent);
 922         ovl_dentry_version_inc(new->d_parent);
 923
 924 out_dput:
 925         dput(newdentry);
 926 out_dput_old:
 927         dput(olddentry);
 928 out_unlock:
 929         unlock_rename(new_upperdir, old_upperdir);
 930 out_revert_creds:
 931         revert_creds(old_cred);
 932 out_drop_write:
 933         ovl_drop_write(old);
 934 out:
 935         dput(opaquedir);
 936         return err;
 937 }
 938
 939 const struct inode_operations ovl_dir_inode_operations = {
 940         .lookup         = ovl_lookup,
 941         .mkdir          = ovl_mkdir,
 942         .symlink        = ovl_symlink,
 943         .unlink         = ovl_unlink,
 944         .rmdir          = ovl_rmdir,
 945         .rename2        = ovl_rename2,
 946         .link           = ovl_link,
 947         .setattr        = ovl_setattr,
 948         .create         = ovl_create,
 949         .mknod          = ovl_mknod,
 950         .permission     = ovl_permission,
 951         .getattr        = ovl_dir_getattr,
 952         .setxattr       = generic_setxattr,
 953         .getxattr       = ovl_getxattr,
 954         .listxattr      = ovl_listxattr,
 955         .removexattr    = ovl_removexattr,
 956         .get_acl        = ovl_get_acl,
 957         .update_time    = ovl_update_time,
 958 };