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                 if (!hardlink) {
 439                         err = security_dentry_create_files_as(dentry,
 440                                         stat->mode, &dentry->d_name, old_cred,
 441                                         override_cred);
 442                         if (err) {
 443                                 put_cred(override_cred);
 444                                 goto out_revert_creds;
 445                         }
 446                 }
 447                 put_cred(override_creds(override_cred));
 448                 put_cred(override_cred);
 449
 450                 if (!ovl_dentry_is_opaque(dentry))
 451                         err = ovl_create_upper(dentry, inode, stat, link,
 452                                                 hardlink);
 453                 else
 454                         err = ovl_create_over_whiteout(dentry, inode, stat,
 455                                                         link, hardlink);
 456         }
 457 out_revert_creds:
 458         revert_creds(old_cred);
 459         if (!err) {
 460                 struct inode *realinode = d_inode(ovl_dentry_upper(dentry));
 461
 462                 WARN_ON(inode->i_mode != realinode->i_mode);
 463                 WARN_ON(!uid_eq(inode->i_uid, realinode->i_uid));
 464                 WARN_ON(!gid_eq(inode->i_gid, realinode->i_gid));
 465         }
 466         return err;
 467 }
 468
 469 static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
 470                              const char *link)
 471 {
 472         int err;
 473         struct inode *inode;
 474         struct kstat stat = {
 475                 .rdev = rdev,
 476         };
 477
 478         err = ovl_want_write(dentry);
 479         if (err)
 480                 goto out;
 481
 482         err = -ENOMEM;
 483         inode = ovl_new_inode(dentry->d_sb, mode);
 484         if (!inode)
 485                 goto out_drop_write;
 486
 487         inode_init_owner(inode, dentry->d_parent->d_inode, mode);
 488         stat.mode = inode->i_mode;
 489
 490         err = ovl_create_or_link(dentry, inode, &stat, link, NULL);
 491         if (err)
 492                 iput(inode);
 493
 494 out_drop_write:
 495         ovl_drop_write(dentry);
 496 out:
 497         return err;
 498 }
 499
 500 static int ovl_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 501                       bool excl)
 502 {
 503         return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL);
 504 }
 505
 506 static int ovl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 507 {
 508         return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL);
 509 }
 510
 511 static int ovl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
 512                      dev_t rdev)
 513 {
 514         /* Don't allow creation of "whiteout" on overlay */
 515         if (S_ISCHR(mode) && rdev == WHITEOUT_DEV)
 516                 return -EPERM;
 517
 518         return ovl_create_object(dentry, mode, rdev, NULL);
 519 }
 520
 521 static int ovl_symlink(struct inode *dir, struct dentry *dentry,
 522                        const char *link)
 523 {
 524         return ovl_create_object(dentry, S_IFLNK, 0, link);
 525 }
 526
 527 static int ovl_link(struct dentry *old, struct inode *newdir,
 528                     struct dentry *new)
 529 {
 530         int err;
 531         struct inode *inode;
 532
 533         err = ovl_want_write(old);
 534         if (err)
 535                 goto out;
 536
 537         err = ovl_copy_up(old);
 538         if (err)
 539                 goto out_drop_write;
 540
 541         inode = d_inode(old);
 542         ihold(inode);
 543
 544         err = ovl_create_or_link(new, inode, NULL, NULL, ovl_dentry_upper(old));
 545         if (err)
 546                 iput(inode);
 547
 548 out_drop_write:
 549         ovl_drop_write(old);
 550 out:
 551         return err;
 552 }
 553
 554 static int ovl_remove_and_whiteout(struct dentry *dentry, bool is_dir)
 555 {
 556         struct dentry *workdir = ovl_workdir(dentry);
 557         struct inode *wdir = workdir->d_inode;
 558         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 559         struct inode *udir = upperdir->d_inode;
 560         struct dentry *whiteout;
 561         struct dentry *upper;
 562         struct dentry *opaquedir = NULL;
 563         int err;
 564         int flags = 0;
 565
 566         if (WARN_ON(!workdir))
 567                 return -EROFS;
 568
 569         if (is_dir) {
 570                 opaquedir = ovl_check_empty_and_clear(dentry);
 571                 err = PTR_ERR(opaquedir);
 572                 if (IS_ERR(opaquedir))
 573                         goto out;
 574         }
 575
 576         err = ovl_lock_rename_workdir(workdir, upperdir);
 577         if (err)
 578                 goto out_dput;
 579
 580         upper = lookup_one_len(dentry->d_name.name, upperdir,
 581                                dentry->d_name.len);
 582         err = PTR_ERR(upper);
 583         if (IS_ERR(upper))
 584                 goto out_unlock;
 585
 586         err = -ESTALE;
 587         if ((opaquedir && upper != opaquedir) ||
 588             (!opaquedir && ovl_dentry_upper(dentry) &&
 589              upper != ovl_dentry_upper(dentry))) {
 590                 goto out_dput_upper;
 591         }
 592
 593         whiteout = ovl_whiteout(workdir, dentry);
 594         err = PTR_ERR(whiteout);
 595         if (IS_ERR(whiteout))
 596                 goto out_dput_upper;
 597
 598         if (d_is_dir(upper))
 599                 flags = RENAME_EXCHANGE;
 600
 601         err = ovl_do_rename(wdir, whiteout, udir, upper, flags);
 602         if (err)
 603                 goto kill_whiteout;
 604         if (flags)
 605                 ovl_cleanup(wdir, upper);
 606
 607         ovl_dentry_version_inc(dentry->d_parent);
 608 out_d_drop:
 609         d_drop(dentry);
 610         dput(whiteout);
 611 out_dput_upper:
 612         dput(upper);
 613 out_unlock:
 614         unlock_rename(workdir, upperdir);
 615 out_dput:
 616         dput(opaquedir);
 617 out:
 618         return err;
 619
 620 kill_whiteout:
 621         ovl_cleanup(wdir, whiteout);
 622         goto out_d_drop;
 623 }
 624
 625 static int ovl_remove_upper(struct dentry *dentry, bool is_dir)
 626 {
 627         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 628         struct inode *dir = upperdir->d_inode;
 629         struct dentry *upper;
 630         int err;
 631
 632         inode_lock_nested(dir, I_MUTEX_PARENT);
 633         upper = lookup_one_len(dentry->d_name.name, upperdir,
 634                                dentry->d_name.len);
 635         err = PTR_ERR(upper);
 636         if (IS_ERR(upper))
 637                 goto out_unlock;
 638
 639         err = -ESTALE;
 640         if (upper == ovl_dentry_upper(dentry)) {
 641                 if (is_dir)
 642                         err = vfs_rmdir(dir, upper);
 643                 else
 644                         err = vfs_unlink(dir, upper, NULL);
 645                 ovl_dentry_version_inc(dentry->d_parent);
 646         }
 647         dput(upper);
 648
 649         /*
 650          * Keeping this dentry hashed would mean having to release
 651          * upperpath/lowerpath, which could only be done if we are the
 652          * sole user of this dentry.  Too tricky...  Just unhash for
 653          * now.
 654          */
 655         if (!err)
 656                 d_drop(dentry);
 657 out_unlock:
 658         inode_unlock(dir);
 659
 660         return err;
 661 }
 662
 663 static inline int ovl_check_sticky(struct dentry *dentry)
 664 {
 665         struct inode *dir = ovl_dentry_real(dentry->d_parent)->d_inode;
 666         struct inode *inode = ovl_dentry_real(dentry)->d_inode;
 667
 668         if (check_sticky(dir, inode))
 669                 return -EPERM;
 670
 671         return 0;
 672 }
 673
 674 static int ovl_do_remove(struct dentry *dentry, bool is_dir)
 675 {
 676         enum ovl_path_type type;
 677         int err;
 678         const struct cred *old_cred;
 679
 680
 681         err = ovl_check_sticky(dentry);
 682         if (err)
 683                 goto out;
 684
 685         err = ovl_want_write(dentry);
 686         if (err)
 687                 goto out;
 688
 689         err = ovl_copy_up(dentry->d_parent);
 690         if (err)
 691                 goto out_drop_write;
 692
 693         type = ovl_path_type(dentry);
 694
 695         old_cred = ovl_override_creds(dentry->d_sb);
 696         if (OVL_TYPE_PURE_UPPER(type))
 697                 err = ovl_remove_upper(dentry, is_dir);
 698         else
 699                 err = ovl_remove_and_whiteout(dentry, is_dir);
 700         revert_creds(old_cred);
 701         if (!err) {
 702                 if (is_dir)
 703                         clear_nlink(dentry->d_inode);
 704                 else
 705                         drop_nlink(dentry->d_inode);
 706         }
 707 out_drop_write:
 708         ovl_drop_write(dentry);
 709 out:
 710         return err;
 711 }
 712
 713 static int ovl_unlink(struct inode *dir, struct dentry *dentry)
 714 {
 715         return ovl_do_remove(dentry, false);
 716 }
 717
 718 static int ovl_rmdir(struct inode *dir, struct dentry *dentry)
 719 {
 720         return ovl_do_remove(dentry, true);
 721 }
 722
 723 static int ovl_rename2(struct inode *olddir, struct dentry *old,
 724                        struct inode *newdir, struct dentry *new,
 725                        unsigned int flags)
 726 {
 727         int err;
 728         enum ovl_path_type old_type;
 729         enum ovl_path_type new_type;
 730         struct dentry *old_upperdir;
 731         struct dentry *new_upperdir;
 732         struct dentry *olddentry;
 733         struct dentry *newdentry;
 734         struct dentry *trap;
 735         bool old_opaque;
 736         bool new_opaque;
 737         bool cleanup_whiteout = false;
 738         bool overwrite = !(flags & RENAME_EXCHANGE);
 739         bool is_dir = d_is_dir(old);
 740         bool new_is_dir = false;
 741         struct dentry *opaquedir = NULL;
 742         const struct cred *old_cred = NULL;
 743
 744         err = -EINVAL;
 745         if (flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE))
 746                 goto out;
 747
 748         flags &= ~RENAME_NOREPLACE;
 749
 750         err = ovl_check_sticky(old);
 751         if (err)
 752                 goto out;
 753
 754         /* Don't copy up directory trees */
 755         old_type = ovl_path_type(old);
 756         err = -EXDEV;
 757         if (OVL_TYPE_MERGE_OR_LOWER(old_type) && is_dir)
 758                 goto out;
 759
 760         if (new->d_inode) {
 761                 err = ovl_check_sticky(new);
 762                 if (err)
 763                         goto out;
 764
 765                 if (d_is_dir(new))
 766                         new_is_dir = true;
 767
 768                 new_type = ovl_path_type(new);
 769                 err = -EXDEV;
 770                 if (!overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir)
 771                         goto out;
 772
 773                 err = 0;
 774                 if (!OVL_TYPE_UPPER(new_type) && !OVL_TYPE_UPPER(old_type)) {
 775                         if (ovl_dentry_lower(old)->d_inode ==
 776                             ovl_dentry_lower(new)->d_inode)
 777                                 goto out;
 778                 }
 779                 if (OVL_TYPE_UPPER(new_type) && OVL_TYPE_UPPER(old_type)) {
 780                         if (ovl_dentry_upper(old)->d_inode ==
 781                             ovl_dentry_upper(new)->d_inode)
 782                                 goto out;
 783                 }
 784         } else {
 785                 if (ovl_dentry_is_opaque(new))
 786                         new_type = __OVL_PATH_UPPER;
 787                 else
 788                         new_type = __OVL_PATH_UPPER | __OVL_PATH_PURE;
 789         }
 790
 791         err = ovl_want_write(old);
 792         if (err)
 793                 goto out;
 794
 795         err = ovl_copy_up(old);
 796         if (err)
 797                 goto out_drop_write;
 798
 799         err = ovl_copy_up(new->d_parent);
 800         if (err)
 801                 goto out_drop_write;
 802         if (!overwrite) {
 803                 err = ovl_copy_up(new);
 804                 if (err)
 805                         goto out_drop_write;
 806         }
 807
 808         old_opaque = !OVL_TYPE_PURE_UPPER(old_type);
 809         new_opaque = !OVL_TYPE_PURE_UPPER(new_type);
 810
 811         old_cred = ovl_override_creds(old->d_sb);
 812
 813         if (overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir) {
 814                 opaquedir = ovl_check_empty_and_clear(new);
 815                 err = PTR_ERR(opaquedir);
 816                 if (IS_ERR(opaquedir)) {
 817                         opaquedir = NULL;
 818                         goto out_revert_creds;
 819                 }
 820         }
 821
 822         if (overwrite) {
 823                 if (old_opaque) {
 824                         if (new->d_inode || !new_opaque) {
 825                                 /* Whiteout source */
 826                                 flags |= RENAME_WHITEOUT;
 827                         } else {
 828                                 /* Switch whiteouts */
 829                                 flags |= RENAME_EXCHANGE;
 830                         }
 831                 } else if (is_dir && !new->d_inode && new_opaque) {
 832                         flags |= RENAME_EXCHANGE;
 833                         cleanup_whiteout = true;
 834                 }
 835         }
 836
 837         old_upperdir = ovl_dentry_upper(old->d_parent);
 838         new_upperdir = ovl_dentry_upper(new->d_parent);
 839
 840         trap = lock_rename(new_upperdir, old_upperdir);
 841
 842
 843         olddentry = lookup_one_len(old->d_name.name, old_upperdir,
 844                                    old->d_name.len);
 845         err = PTR_ERR(olddentry);
 846         if (IS_ERR(olddentry))
 847                 goto out_unlock;
 848
 849         err = -ESTALE;
 850         if (olddentry != ovl_dentry_upper(old))
 851                 goto out_dput_old;
 852
 853         newdentry = lookup_one_len(new->d_name.name, new_upperdir,
 854                                    new->d_name.len);
 855         err = PTR_ERR(newdentry);
 856         if (IS_ERR(newdentry))
 857                 goto out_dput_old;
 858
 859         err = -ESTALE;
 860         if (ovl_dentry_upper(new)) {
 861                 if (opaquedir) {
 862                         if (newdentry != opaquedir)
 863                                 goto out_dput;
 864                 } else {
 865                         if (newdentry != ovl_dentry_upper(new))
 866                                 goto out_dput;
 867                 }
 868         } else {
 869                 if (!d_is_negative(newdentry) &&
 870                     (!new_opaque || !ovl_is_whiteout(newdentry)))
 871                         goto out_dput;
 872         }
 873
 874         if (olddentry == trap)
 875                 goto out_dput;
 876         if (newdentry == trap)
 877                 goto out_dput;
 878
 879         if (is_dir && !old_opaque && new_opaque) {
 880                 err = ovl_set_opaque(olddentry);
 881                 if (err)
 882                         goto out_dput;
 883         }
 884         if (!overwrite && new_is_dir && old_opaque && !new_opaque) {
 885                 err = ovl_set_opaque(newdentry);
 886                 if (err)
 887                         goto out_dput;
 888         }
 889
 890         if (old_opaque || new_opaque) {
 891                 err = ovl_do_rename(old_upperdir->d_inode, olddentry,
 892                                     new_upperdir->d_inode, newdentry,
 893                                     flags);
 894         } else {
 895                 /* No debug for the plain case */
 896                 BUG_ON(flags & ~RENAME_EXCHANGE);
 897                 err = vfs_rename(old_upperdir->d_inode, olddentry,
 898                                  new_upperdir->d_inode, newdentry,
 899                                  NULL, flags);
 900         }
 901
 902         if (err) {
 903                 if (is_dir && !old_opaque && new_opaque)
 904                         ovl_remove_opaque(olddentry);
 905                 if (!overwrite && new_is_dir && old_opaque && !new_opaque)
 906                         ovl_remove_opaque(newdentry);
 907                 goto out_dput;
 908         }
 909
 910         if (is_dir && old_opaque && !new_opaque)
 911                 ovl_remove_opaque(olddentry);
 912         if (!overwrite && new_is_dir && !old_opaque && new_opaque)
 913                 ovl_remove_opaque(newdentry);
 914
 915         /*
 916          * Old dentry now lives in different location. Dentries in
 917          * lowerstack are stale. We cannot drop them here because
 918          * access to them is lockless. This could be only pure upper
 919          * or opaque directory - numlower is zero. Or upper non-dir
 920          * entry - its pureness is tracked by flag opaque.
 921          */
 922         if (old_opaque != new_opaque) {
 923                 ovl_dentry_set_opaque(old, new_opaque);
 924                 if (!overwrite)
 925                         ovl_dentry_set_opaque(new, old_opaque);
 926         }
 927
 928         if (cleanup_whiteout)
 929                 ovl_cleanup(old_upperdir->d_inode, newdentry);
 930
 931         ovl_dentry_version_inc(old->d_parent);
 932         ovl_dentry_version_inc(new->d_parent);
 933
 934 out_dput:
 935         dput(newdentry);
 936 out_dput_old:
 937         dput(olddentry);
 938 out_unlock:
 939         unlock_rename(new_upperdir, old_upperdir);
 940 out_revert_creds:
 941         revert_creds(old_cred);
 942 out_drop_write:
 943         ovl_drop_write(old);
 944 out:
 945         dput(opaquedir);
 946         return err;
 947 }
 948
 949 const struct inode_operations ovl_dir_inode_operations = {
 950         .lookup         = ovl_lookup,
 951         .mkdir          = ovl_mkdir,
 952         .symlink        = ovl_symlink,
 953         .unlink         = ovl_unlink,
 954         .rmdir          = ovl_rmdir,
 955         .rename2        = ovl_rename2,
 956         .link           = ovl_link,
 957         .setattr        = ovl_setattr,
 958         .create         = ovl_create,
 959         .mknod          = ovl_mknod,
 960         .permission     = ovl_permission,
 961         .getattr        = ovl_dir_getattr,
 962         .setxattr       = generic_setxattr,
 963         .getxattr       = ovl_getxattr,
 964         .listxattr      = ovl_listxattr,
 965         .removexattr    = ovl_removexattr,
 966         .get_acl        = ovl_get_acl,
 967         .update_time    = ovl_update_time,
 968 };