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         LIST_HEAD(list);
 311
 312         err = ovl_check_empty_dir(dentry, &list);
 313         if (err)
 314                 ret = ERR_PTR(err);
 315         else {
 316                 /*
 317                  * If no upperdentry then skip clearing whiteouts.
 318                  *
 319                  * Can race with copy-up, since we don't hold the upperdir
 320                  * mutex.  Doesn't matter, since copy-up can't create a
 321                  * non-empty directory from an empty one.
 322                  */
 323                 if (ovl_dentry_upper(dentry))
 324                         ret = ovl_clear_empty(dentry, &list);
 325         }
 326
 327         ovl_cache_free(&list);
 328
 329         return ret;
 330 }
 331
 332 static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
 333                                     struct kstat *stat, const char *link,
 334                                     struct dentry *hardlink)
 335 {
 336         struct dentry *workdir = ovl_workdir(dentry);
 337         struct inode *wdir = workdir->d_inode;
 338         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 339         struct inode *udir = upperdir->d_inode;
 340         struct dentry *upper;
 341         struct dentry *newdentry;
 342         int err;
 343
 344         if (WARN_ON(!workdir))
 345                 return -EROFS;
 346
 347         err = ovl_lock_rename_workdir(workdir, upperdir);
 348         if (err)
 349                 goto out;
 350
 351         newdentry = ovl_lookup_temp(workdir, dentry);
 352         err = PTR_ERR(newdentry);
 353         if (IS_ERR(newdentry))
 354                 goto out_unlock;
 355
 356         upper = lookup_one_len(dentry->d_name.name, upperdir,
 357                                dentry->d_name.len);
 358         err = PTR_ERR(upper);
 359         if (IS_ERR(upper))
 360                 goto out_dput;
 361
 362         err = ovl_create_real(wdir, newdentry, stat, link, hardlink, true);
 363         if (err)
 364                 goto out_dput2;
 365
 366         /*
 367          * mode could have been mutilated due to umask (e.g. sgid directory)
 368          */
 369         if (!hardlink &&
 370             !S_ISLNK(stat->mode) && newdentry->d_inode->i_mode != stat->mode) {
 371                 struct iattr attr = {
 372                         .ia_valid = ATTR_MODE,
 373                         .ia_mode = stat->mode,
 374                 };
 375                 inode_lock(newdentry->d_inode);
 376                 err = notify_change(newdentry, &attr, NULL);
 377                 inode_unlock(newdentry->d_inode);
 378                 if (err)
 379                         goto out_cleanup;
 380         }
 381
 382         if (!hardlink && S_ISDIR(stat->mode)) {
 383                 err = ovl_set_opaque(newdentry);
 384                 if (err)
 385                         goto out_cleanup;
 386
 387                 err = ovl_do_rename(wdir, newdentry, udir, upper,
 388                                     RENAME_EXCHANGE);
 389                 if (err)
 390                         goto out_cleanup;
 391
 392                 ovl_cleanup(wdir, upper);
 393         } else {
 394                 err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
 395                 if (err)
 396                         goto out_cleanup;
 397         }
 398         ovl_instantiate(dentry, inode, newdentry, !!hardlink);
 399         newdentry = NULL;
 400 out_dput2:
 401         dput(upper);
 402 out_dput:
 403         dput(newdentry);
 404 out_unlock:
 405         unlock_rename(workdir, upperdir);
 406 out:
 407         return err;
 408
 409 out_cleanup:
 410         ovl_cleanup(wdir, newdentry);
 411         goto out_dput2;
 412 }
 413
 414 static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
 415                               struct kstat *stat, const char *link,
 416                               struct dentry *hardlink)
 417 {
 418         int err;
 419         const struct cred *old_cred;
 420         struct cred *override_cred;
 421
 422         err = ovl_copy_up(dentry->d_parent);
 423         if (err)
 424                 return err;
 425
 426         old_cred = ovl_override_creds(dentry->d_sb);
 427         err = -ENOMEM;
 428         override_cred = prepare_creds();
 429         if (override_cred) {
 430                 override_cred->fsuid = inode->i_uid;
 431                 override_cred->fsgid = inode->i_gid;
 432                 put_cred(override_creds(override_cred));
 433                 put_cred(override_cred);
 434
 435                 if (!ovl_dentry_is_opaque(dentry))
 436                         err = ovl_create_upper(dentry, inode, stat, link,
 437                                                 hardlink);
 438                 else
 439                         err = ovl_create_over_whiteout(dentry, inode, stat,
 440                                                         link, hardlink);
 441         }
 442         revert_creds(old_cred);
 443         if (!err) {
 444                 struct inode *realinode = d_inode(ovl_dentry_upper(dentry));
 445
 446                 WARN_ON(inode->i_mode != realinode->i_mode);
 447                 WARN_ON(!uid_eq(inode->i_uid, realinode->i_uid));
 448                 WARN_ON(!gid_eq(inode->i_gid, realinode->i_gid));
 449         }
 450         return err;
 451 }
 452
 453 static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
 454                              const char *link)
 455 {
 456         int err;
 457         struct inode *inode;
 458         struct kstat stat = {
 459                 .rdev = rdev,
 460         };
 461
 462         err = ovl_want_write(dentry);
 463         if (err)
 464                 goto out;
 465
 466         err = -ENOMEM;
 467         inode = ovl_new_inode(dentry->d_sb, mode);
 468         if (!inode)
 469                 goto out_drop_write;
 470
 471         inode_init_owner(inode, dentry->d_parent->d_inode, mode);
 472         stat.mode = inode->i_mode;
 473
 474         err = ovl_create_or_link(dentry, inode, &stat, link, NULL);
 475         if (err)
 476                 iput(inode);
 477
 478 out_drop_write:
 479         ovl_drop_write(dentry);
 480 out:
 481         return err;
 482 }
 483
 484 static int ovl_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 485                       bool excl)
 486 {
 487         return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL);
 488 }
 489
 490 static int ovl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 491 {
 492         return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL);
 493 }
 494
 495 static int ovl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
 496                      dev_t rdev)
 497 {
 498         /* Don't allow creation of "whiteout" on overlay */
 499         if (S_ISCHR(mode) && rdev == WHITEOUT_DEV)
 500                 return -EPERM;
 501
 502         return ovl_create_object(dentry, mode, rdev, NULL);
 503 }
 504
 505 static int ovl_symlink(struct inode *dir, struct dentry *dentry,
 506                        const char *link)
 507 {
 508         return ovl_create_object(dentry, S_IFLNK, 0, link);
 509 }
 510
 511 static int ovl_link(struct dentry *old, struct inode *newdir,
 512                     struct dentry *new)
 513 {
 514         int err;
 515         struct inode *inode;
 516
 517         err = ovl_want_write(old);
 518         if (err)
 519                 goto out;
 520
 521         err = ovl_copy_up(old);
 522         if (err)
 523                 goto out_drop_write;
 524
 525         inode = d_inode(old);
 526         ihold(inode);
 527
 528         err = ovl_create_or_link(new, inode, NULL, NULL, ovl_dentry_upper(old));
 529         if (err)
 530                 iput(inode);
 531
 532 out_drop_write:
 533         ovl_drop_write(old);
 534 out:
 535         return err;
 536 }
 537
 538 static int ovl_remove_and_whiteout(struct dentry *dentry, bool is_dir)
 539 {
 540         struct dentry *workdir = ovl_workdir(dentry);
 541         struct inode *wdir = workdir->d_inode;
 542         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 543         struct inode *udir = upperdir->d_inode;
 544         struct dentry *whiteout;
 545         struct dentry *upper;
 546         struct dentry *opaquedir = NULL;
 547         int err;
 548         int flags = 0;
 549
 550         if (WARN_ON(!workdir))
 551                 return -EROFS;
 552
 553         if (is_dir) {
 554                 if (OVL_TYPE_MERGE_OR_LOWER(ovl_path_type(dentry))) {
 555                         opaquedir = ovl_check_empty_and_clear(dentry);
 556                         err = PTR_ERR(opaquedir);
 557                         if (IS_ERR(opaquedir))
 558                                 goto out;
 559                 } else {
 560                         LIST_HEAD(list);
 561
 562                         /*
 563                          * When removing an empty opaque directory, then it
 564                          * makes no sense to replace it with an exact replica of
 565                          * itself.  But emptiness still needs to be checked.
 566                          */
 567                         err = ovl_check_empty_dir(dentry, &list);
 568                         ovl_cache_free(&list);
 569                         if (err)
 570                                 goto out;
 571                 }
 572         }
 573
 574         err = ovl_lock_rename_workdir(workdir, upperdir);
 575         if (err)
 576                 goto out_dput;
 577
 578         upper = lookup_one_len(dentry->d_name.name, upperdir,
 579                                dentry->d_name.len);
 580         err = PTR_ERR(upper);
 581         if (IS_ERR(upper))
 582                 goto out_unlock;
 583
 584         err = -ESTALE;
 585         if ((opaquedir && upper != opaquedir) ||
 586             (!opaquedir && ovl_dentry_upper(dentry) &&
 587              upper != ovl_dentry_upper(dentry))) {
 588                 goto out_dput_upper;
 589         }
 590
 591         whiteout = ovl_whiteout(workdir, dentry);
 592         err = PTR_ERR(whiteout);
 593         if (IS_ERR(whiteout))
 594                 goto out_dput_upper;
 595
 596         if (d_is_dir(upper))
 597                 flags = RENAME_EXCHANGE;
 598
 599         err = ovl_do_rename(wdir, whiteout, udir, upper, flags);
 600         if (err)
 601                 goto kill_whiteout;
 602         if (flags)
 603                 ovl_cleanup(wdir, upper);
 604
 605         ovl_dentry_version_inc(dentry->d_parent);
 606 out_d_drop:
 607         d_drop(dentry);
 608         dput(whiteout);
 609 out_dput_upper:
 610         dput(upper);
 611 out_unlock:
 612         unlock_rename(workdir, upperdir);
 613 out_dput:
 614         dput(opaquedir);
 615 out:
 616         return err;
 617
 618 kill_whiteout:
 619         ovl_cleanup(wdir, whiteout);
 620         goto out_d_drop;
 621 }
 622
 623 static int ovl_remove_upper(struct dentry *dentry, bool is_dir)
 624 {
 625         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 626         struct inode *dir = upperdir->d_inode;
 627         struct dentry *upper;
 628         int err;
 629
 630         inode_lock_nested(dir, I_MUTEX_PARENT);
 631         upper = lookup_one_len(dentry->d_name.name, upperdir,
 632                                dentry->d_name.len);
 633         err = PTR_ERR(upper);
 634         if (IS_ERR(upper))
 635                 goto out_unlock;
 636
 637         err = -ESTALE;
 638         if (upper == ovl_dentry_upper(dentry)) {
 639                 if (is_dir)
 640                         err = vfs_rmdir(dir, upper);
 641                 else
 642                         err = vfs_unlink(dir, upper, NULL);
 643                 ovl_dentry_version_inc(dentry->d_parent);
 644         }
 645         dput(upper);
 646
 647         /*
 648          * Keeping this dentry hashed would mean having to release
 649          * upperpath/lowerpath, which could only be done if we are the
 650          * sole user of this dentry.  Too tricky...  Just unhash for
 651          * now.
 652          */
 653         if (!err)
 654                 d_drop(dentry);
 655 out_unlock:
 656         inode_unlock(dir);
 657
 658         return err;
 659 }
 660
 661 static inline int ovl_check_sticky(struct dentry *dentry)
 662 {
 663         struct inode *dir = ovl_dentry_real(dentry->d_parent)->d_inode;
 664         struct inode *inode = ovl_dentry_real(dentry)->d_inode;
 665
 666         if (check_sticky(dir, inode))
 667                 return -EPERM;
 668
 669         return 0;
 670 }
 671
 672 static int ovl_do_remove(struct dentry *dentry, bool is_dir)
 673 {
 674         enum ovl_path_type type;
 675         int err;
 676         const struct cred *old_cred;
 677
 678
 679         err = ovl_check_sticky(dentry);
 680         if (err)
 681                 goto out;
 682
 683         err = ovl_want_write(dentry);
 684         if (err)
 685                 goto out;
 686
 687         err = ovl_copy_up(dentry->d_parent);
 688         if (err)
 689                 goto out_drop_write;
 690
 691         type = ovl_path_type(dentry);
 692
 693         old_cred = ovl_override_creds(dentry->d_sb);
 694         if (OVL_TYPE_PURE_UPPER(type))
 695                 err = ovl_remove_upper(dentry, is_dir);
 696         else
 697                 err = ovl_remove_and_whiteout(dentry, is_dir);
 698         revert_creds(old_cred);
 699         if (!err && !is_dir)
 700                 drop_nlink(dentry->d_inode);
 701 out_drop_write:
 702         ovl_drop_write(dentry);
 703 out:
 704         return err;
 705 }
 706
 707 static int ovl_unlink(struct inode *dir, struct dentry *dentry)
 708 {
 709         return ovl_do_remove(dentry, false);
 710 }
 711
 712 static int ovl_rmdir(struct inode *dir, struct dentry *dentry)
 713 {
 714         return ovl_do_remove(dentry, true);
 715 }
 716
 717 static int ovl_rename2(struct inode *olddir, struct dentry *old,
 718                        struct inode *newdir, struct dentry *new,
 719                        unsigned int flags)
 720 {
 721         int err;
 722         enum ovl_path_type old_type;
 723         enum ovl_path_type new_type;
 724         struct dentry *old_upperdir;
 725         struct dentry *new_upperdir;
 726         struct dentry *olddentry;
 727         struct dentry *newdentry;
 728         struct dentry *trap;
 729         bool old_opaque;
 730         bool new_opaque;
 731         bool cleanup_whiteout = false;
 732         bool overwrite = !(flags & RENAME_EXCHANGE);
 733         bool is_dir = d_is_dir(old);
 734         bool new_is_dir = false;
 735         struct dentry *opaquedir = NULL;
 736         const struct cred *old_cred = NULL;
 737
 738         err = -EINVAL;
 739         if (flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE))
 740                 goto out;
 741
 742         flags &= ~RENAME_NOREPLACE;
 743
 744         err = ovl_check_sticky(old);
 745         if (err)
 746                 goto out;
 747
 748         /* Don't copy up directory trees */
 749         old_type = ovl_path_type(old);
 750         err = -EXDEV;
 751         if (OVL_TYPE_MERGE_OR_LOWER(old_type) && is_dir)
 752                 goto out;
 753
 754         if (new->d_inode) {
 755                 err = ovl_check_sticky(new);
 756                 if (err)
 757                         goto out;
 758
 759                 if (d_is_dir(new))
 760                         new_is_dir = true;
 761
 762                 new_type = ovl_path_type(new);
 763                 err = -EXDEV;
 764                 if (!overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir)
 765                         goto out;
 766
 767                 err = 0;
 768                 if (!OVL_TYPE_UPPER(new_type) && !OVL_TYPE_UPPER(old_type)) {
 769                         if (ovl_dentry_lower(old)->d_inode ==
 770                             ovl_dentry_lower(new)->d_inode)
 771                                 goto out;
 772                 }
 773                 if (OVL_TYPE_UPPER(new_type) && OVL_TYPE_UPPER(old_type)) {
 774                         if (ovl_dentry_upper(old)->d_inode ==
 775                             ovl_dentry_upper(new)->d_inode)
 776                                 goto out;
 777                 }
 778         } else {
 779                 if (ovl_dentry_is_opaque(new))
 780                         new_type = __OVL_PATH_UPPER;
 781                 else
 782                         new_type = __OVL_PATH_UPPER | __OVL_PATH_PURE;
 783         }
 784
 785         err = ovl_want_write(old);
 786         if (err)
 787                 goto out;
 788
 789         err = ovl_copy_up(old);
 790         if (err)
 791                 goto out_drop_write;
 792
 793         err = ovl_copy_up(new->d_parent);
 794         if (err)
 795                 goto out_drop_write;
 796         if (!overwrite) {
 797                 err = ovl_copy_up(new);
 798                 if (err)
 799                         goto out_drop_write;
 800         }
 801
 802         old_opaque = !OVL_TYPE_PURE_UPPER(old_type);
 803         new_opaque = !OVL_TYPE_PURE_UPPER(new_type);
 804
 805         old_cred = ovl_override_creds(old->d_sb);
 806
 807         if (overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir) {
 808                 opaquedir = ovl_check_empty_and_clear(new);
 809                 err = PTR_ERR(opaquedir);
 810                 if (IS_ERR(opaquedir)) {
 811                         opaquedir = NULL;
 812                         goto out_revert_creds;
 813                 }
 814         }
 815
 816         if (overwrite) {
 817                 if (old_opaque) {
 818                         if (new->d_inode || !new_opaque) {
 819                                 /* Whiteout source */
 820                                 flags |= RENAME_WHITEOUT;
 821                         } else {
 822                                 /* Switch whiteouts */
 823                                 flags |= RENAME_EXCHANGE;
 824                         }
 825                 } else if (is_dir && !new->d_inode && new_opaque) {
 826                         flags |= RENAME_EXCHANGE;
 827                         cleanup_whiteout = true;
 828                 }
 829         }
 830
 831         old_upperdir = ovl_dentry_upper(old->d_parent);
 832         new_upperdir = ovl_dentry_upper(new->d_parent);
 833
 834         trap = lock_rename(new_upperdir, old_upperdir);
 835
 836
 837         olddentry = lookup_one_len(old->d_name.name, old_upperdir,
 838                                    old->d_name.len);
 839         err = PTR_ERR(olddentry);
 840         if (IS_ERR(olddentry))
 841                 goto out_unlock;
 842
 843         err = -ESTALE;
 844         if (olddentry != ovl_dentry_upper(old))
 845                 goto out_dput_old;
 846
 847         newdentry = lookup_one_len(new->d_name.name, new_upperdir,
 848                                    new->d_name.len);
 849         err = PTR_ERR(newdentry);
 850         if (IS_ERR(newdentry))
 851                 goto out_dput_old;
 852
 853         err = -ESTALE;
 854         if (ovl_dentry_upper(new)) {
 855                 if (opaquedir) {
 856                         if (newdentry != opaquedir)
 857                                 goto out_dput;
 858                 } else {
 859                         if (newdentry != ovl_dentry_upper(new))
 860                                 goto out_dput;
 861                 }
 862         } else {
 863                 if (!d_is_negative(newdentry) &&
 864                     (!new_opaque || !ovl_is_whiteout(newdentry)))
 865                         goto out_dput;
 866         }
 867
 868         if (olddentry == trap)
 869                 goto out_dput;
 870         if (newdentry == trap)
 871                 goto out_dput;
 872
 873         if (is_dir && !old_opaque && new_opaque) {
 874                 err = ovl_set_opaque(olddentry);
 875                 if (err)
 876                         goto out_dput;
 877         }
 878         if (!overwrite && new_is_dir && old_opaque && !new_opaque) {
 879                 err = ovl_set_opaque(newdentry);
 880                 if (err)
 881                         goto out_dput;
 882         }
 883
 884         if (old_opaque || new_opaque) {
 885                 err = ovl_do_rename(old_upperdir->d_inode, olddentry,
 886                                     new_upperdir->d_inode, newdentry,
 887                                     flags);
 888         } else {
 889                 /* No debug for the plain case */
 890                 BUG_ON(flags & ~RENAME_EXCHANGE);
 891                 err = vfs_rename(old_upperdir->d_inode, olddentry,
 892                                  new_upperdir->d_inode, newdentry,
 893                                  NULL, flags);
 894         }
 895
 896         if (err) {
 897                 if (is_dir && !old_opaque && new_opaque)
 898                         ovl_remove_opaque(olddentry);
 899                 if (!overwrite && new_is_dir && old_opaque && !new_opaque)
 900                         ovl_remove_opaque(newdentry);
 901                 goto out_dput;
 902         }
 903
 904         if (is_dir && old_opaque && !new_opaque)
 905                 ovl_remove_opaque(olddentry);
 906         if (!overwrite && new_is_dir && !old_opaque && new_opaque)
 907                 ovl_remove_opaque(newdentry);
 908
 909         /*
 910          * Old dentry now lives in different location. Dentries in
 911          * lowerstack are stale. We cannot drop them here because
 912          * access to them is lockless. This could be only pure upper
 913          * or opaque directory - numlower is zero. Or upper non-dir
 914          * entry - its pureness is tracked by flag opaque.
 915          */
 916         if (old_opaque != new_opaque) {
 917                 ovl_dentry_set_opaque(old, new_opaque);
 918                 if (!overwrite)
 919                         ovl_dentry_set_opaque(new, old_opaque);
 920         }
 921
 922         if (cleanup_whiteout)
 923                 ovl_cleanup(old_upperdir->d_inode, newdentry);
 924
 925         ovl_dentry_version_inc(old->d_parent);
 926         ovl_dentry_version_inc(new->d_parent);
 927
 928 out_dput:
 929         dput(newdentry);
 930 out_dput_old:
 931         dput(olddentry);
 932 out_unlock:
 933         unlock_rename(new_upperdir, old_upperdir);
 934 out_revert_creds:
 935         revert_creds(old_cred);
 936 out_drop_write:
 937         ovl_drop_write(old);
 938 out:
 939         dput(opaquedir);
 940         return err;
 941 }
 942
 943 const struct inode_operations ovl_dir_inode_operations = {
 944         .lookup         = ovl_lookup,
 945         .mkdir          = ovl_mkdir,
 946         .symlink        = ovl_symlink,
 947         .unlink         = ovl_unlink,
 948         .rmdir          = ovl_rmdir,
 949         .rename2        = ovl_rename2,
 950         .link           = ovl_link,
 951         .setattr        = ovl_setattr,
 952         .create         = ovl_create,
 953         .mknod          = ovl_mknod,
 954         .permission     = ovl_permission,
 955         .getattr        = ovl_dir_getattr,
 956         .setxattr       = ovl_setxattr,
 957         .getxattr       = ovl_getxattr,
 958         .listxattr      = ovl_listxattr,
 959         .removexattr    = ovl_removexattr,
 960         .get_acl        = ovl_get_acl,
 961         .update_time    = ovl_update_time,
 962 };