fs/overlayfs/copy_up.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/module.h>
  11 #include <linux/fs.h>
  12 #include <linux/slab.h>
  13 #include <linux/file.h>
  14 #include <linux/splice.h>
  15 #include <linux/xattr.h>
  16 #include <linux/security.h>
  17 #include <linux/uaccess.h>
  18 #include <linux/sched/signal.h>
  19 #include <linux/cred.h>
  20 #include <linux/namei.h>
  21 #include <linux/fdtable.h>
  22 #include <linux/ratelimit.h>
  23 #include <linux/exportfs.h>
  24 #include "overlayfs.h"
  25
  26 #define OVL_COPY_UP_CHUNK_SIZE (1 << 20)
  27
  28 static bool __read_mostly ovl_check_copy_up;
  29 module_param_named(check_copy_up, ovl_check_copy_up, bool,
  30                    S_IWUSR | S_IRUGO);
  31 MODULE_PARM_DESC(ovl_check_copy_up,
  32                  "Warn on copy-up when causing process also has a R/O fd open");
  33
  34 static int ovl_check_fd(const void *data, struct file *f, unsigned int fd)
  35 {
  36         const struct dentry *dentry = data;
  37
  38         if (file_inode(f) == d_inode(dentry))
  39                 pr_warn_ratelimited("overlayfs: Warning: Copying up %pD, but open R/O on fd %u which will cease to be coherent [pid=%d %s]\n",
  40                                     f, fd, current->pid, current->comm);
  41         return 0;
  42 }
  43
  44 /*
  45  * Check the fds open by this process and warn if something like the following
  46  * scenario is about to occur:
  47  *
  48  *      fd1 = open("foo", O_RDONLY);
  49  *      fd2 = open("foo", O_RDWR);
  50  */
  51 static void ovl_do_check_copy_up(struct dentry *dentry)
  52 {
  53         if (ovl_check_copy_up)
  54                 iterate_fd(current->files, 0, ovl_check_fd, dentry);
  55 }
  56
  57 int ovl_copy_xattr(struct dentry *old, struct dentry *new)
  58 {
  59         ssize_t list_size, size, value_size = 0;
  60         char *buf, *name, *value = NULL;
  61         int uninitialized_var(error);
  62         size_t slen;
  63
  64         if (!(old->d_inode->i_opflags & IOP_XATTR) ||
  65             !(new->d_inode->i_opflags & IOP_XATTR))
  66                 return 0;
  67
  68         list_size = vfs_listxattr(old, NULL, 0);
  69         if (list_size <= 0) {
  70                 if (list_size == -EOPNOTSUPP)
  71                         return 0;
  72                 return list_size;
  73         }
  74
  75         buf = kzalloc(list_size, GFP_KERNEL);
  76         if (!buf)
  77                 return -ENOMEM;
  78
  79         list_size = vfs_listxattr(old, buf, list_size);
  80         if (list_size <= 0) {
  81                 error = list_size;
  82                 goto out;
  83         }
  84
  85         for (name = buf; list_size; name += slen) {
  86                 slen = strnlen(name, list_size) + 1;
  87
  88                 /* underlying fs providing us with an broken xattr list? */
  89                 if (WARN_ON(slen > list_size)) {
  90                         error = -EIO;
  91                         break;
  92                 }
  93                 list_size -= slen;
  94
  95                 if (ovl_is_private_xattr(name))
  96                         continue;
  97 retry:
  98                 size = vfs_getxattr(old, name, value, value_size);
  99                 if (size == -ERANGE)
 100                         size = vfs_getxattr(old, name, NULL, 0);
 101
 102                 if (size < 0) {
 103                         error = size;
 104                         break;
 105                 }
 106
 107                 if (size > value_size) {
 108                         void *new;
 109
 110                         new = krealloc(value, size, GFP_KERNEL);
 111                         if (!new) {
 112                                 error = -ENOMEM;
 113                                 break;
 114                         }
 115                         value = new;
 116                         value_size = size;
 117                         goto retry;
 118                 }
 119
 120                 error = security_inode_copy_up_xattr(name);
 121                 if (error < 0 && error != -EOPNOTSUPP)
 122                         break;
 123                 if (error == 1) {
 124                         error = 0;
 125                         continue; /* Discard */
 126                 }
 127                 error = vfs_setxattr(new, name, value, size, 0);
 128                 if (error)
 129                         break;
 130         }
 131         kfree(value);
 132 out:
 133         kfree(buf);
 134         return error;
 135 }
 136
 137 static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len)
 138 {
 139         struct file *old_file;
 140         struct file *new_file;
 141         loff_t old_pos = 0;
 142         loff_t new_pos = 0;
 143         int error = 0;
 144
 145         if (len == 0)
 146                 return 0;
 147
 148         old_file = ovl_path_open(old, O_LARGEFILE | O_RDONLY);
 149         if (IS_ERR(old_file))
 150                 return PTR_ERR(old_file);
 151
 152         new_file = ovl_path_open(new, O_LARGEFILE | O_WRONLY);
 153         if (IS_ERR(new_file)) {
 154                 error = PTR_ERR(new_file);
 155                 goto out_fput;
 156         }
 157
 158         /* Try to use clone_file_range to clone up within the same fs */
 159         error = vfs_clone_file_range(old_file, 0, new_file, 0, len);
 160         if (!error)
 161                 goto out;
 162         /* Couldn't clone, so now we try to copy the data */
 163         error = 0;
 164
 165         /* FIXME: copy up sparse files efficiently */
 166         while (len) {
 167                 size_t this_len = OVL_COPY_UP_CHUNK_SIZE;
 168                 long bytes;
 169
 170                 if (len < this_len)
 171                         this_len = len;
 172
 173                 if (signal_pending_state(TASK_KILLABLE, current)) {
 174                         error = -EINTR;
 175                         break;
 176                 }
 177
 178                 bytes = do_splice_direct(old_file, &old_pos,
 179                                          new_file, &new_pos,
 180                                          this_len, SPLICE_F_MOVE);
 181                 if (bytes <= 0) {
 182                         error = bytes;
 183                         break;
 184                 }
 185                 WARN_ON(old_pos != new_pos);
 186
 187                 len -= bytes;
 188         }
 189 out:
 190         if (!error)
 191                 error = vfs_fsync(new_file, 0);
 192         fput(new_file);
 193 out_fput:
 194         fput(old_file);
 195         return error;
 196 }
 197
 198 static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat)
 199 {
 200         struct iattr attr = {
 201                 .ia_valid =
 202                      ATTR_ATIME | ATTR_MTIME | ATTR_ATIME_SET | ATTR_MTIME_SET,
 203                 .ia_atime = stat->atime,
 204                 .ia_mtime = stat->mtime,
 205         };
 206
 207         return notify_change(upperdentry, &attr, NULL);
 208 }
 209
 210 int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat)
 211 {
 212         int err = 0;
 213
 214         /*
 215          * For the most part we want to set the mode bits before setting
 216          * the user, otherwise the current context might lack permission
 217          * for setting the mode. However for sxid/sticky bits we want
 218          * the operation to fail if the current user isn't privileged
 219          * towards the resulting inode. So we first set the mode but
 220          * exclude the sxid/sticky bits, then set the user, then set the
 221          * mode again if any of the sxid/sticky bits are set.
 222          */
 223         if (!S_ISLNK(stat->mode)) {
 224                 struct iattr attr = {
 225                         .ia_valid = ATTR_MODE,
 226                         .ia_mode = stat->mode & ~(S_ISUID|S_ISGID|S_ISVTX),
 227                 };
 228                 err = notify_change(upperdentry, &attr, NULL);
 229         }
 230         if (!err) {
 231                 struct iattr attr = {
 232                         .ia_valid = ATTR_UID | ATTR_GID,
 233                         .ia_uid = stat->uid,
 234                         .ia_gid = stat->gid,
 235                 };
 236                 err = notify_change(upperdentry, &attr, NULL);
 237         }
 238         if (!err && !S_ISLNK(stat->mode) &&
 239             (stat->mode & (S_ISUID|S_ISGID|S_ISVTX))) {
 240                 struct iattr attr = {
 241                         .ia_valid = ATTR_MODE,
 242                         .ia_mode = stat->mode,
 243                 };
 244                 err = notify_change(upperdentry, &attr, NULL);
 245         }
 246         if (!err)
 247                 ovl_set_timestamps(upperdentry, stat);
 248
 249         return err;
 250 }
 251
 252 struct ovl_fh *ovl_encode_fh(struct dentry *lower, bool is_upper)
 253 {
 254         struct ovl_fh *fh;
 255         int fh_type, fh_len, dwords;
 256         void *buf;
 257         int buflen = MAX_HANDLE_SZ;
 258         uuid_t *uuid = &lower->d_sb->s_uuid;
 259
 260         buf = kmalloc(buflen, GFP_KERNEL);
 261         if (!buf)
 262                 return ERR_PTR(-ENOMEM);
 263
 264         /*
 265          * We encode a non-connectable file handle for non-dir, because we
 266          * only need to find the lower inode number and we don't want to pay
 267          * the price or reconnecting the dentry.
 268          */
 269         dwords = buflen >> 2;
 270         fh_type = exportfs_encode_fh(lower, buf, &dwords, 0);
 271         buflen = (dwords << 2);
 272
 273         fh = ERR_PTR(-EIO);
 274         if (WARN_ON(fh_type < 0) ||
 275             WARN_ON(buflen > MAX_HANDLE_SZ) ||
 276             WARN_ON(fh_type == FILEID_INVALID))
 277                 goto out;
 278
 279         BUILD_BUG_ON(MAX_HANDLE_SZ + offsetof(struct ovl_fh, fid) > 255);
 280         fh_len = offsetof(struct ovl_fh, fid) + buflen;
 281         fh = kmalloc(fh_len, GFP_KERNEL);
 282         if (!fh) {
 283                 fh = ERR_PTR(-ENOMEM);
 284                 goto out;
 285         }
 286
 287         fh->version = OVL_FH_VERSION;
 288         fh->magic = OVL_FH_MAGIC;
 289         fh->type = fh_type;
 290         fh->flags = OVL_FH_FLAG_CPU_ENDIAN;
 291         /*
 292          * When we will want to decode an overlay dentry from this handle
 293          * and all layers are on the same fs, if we get a disconncted real
 294          * dentry when we decode fid, the only way to tell if we should assign
 295          * it to upperdentry or to lowerstack is by checking this flag.
 296          */
 297         if (is_upper)
 298                 fh->flags |= OVL_FH_FLAG_PATH_UPPER;
 299         fh->len = fh_len;
 300         fh->uuid = *uuid;
 301         memcpy(fh->fid, buf, buflen);
 302
 303 out:
 304         kfree(buf);
 305         return fh;
 306 }
 307
 308 static int ovl_set_origin(struct dentry *dentry, struct dentry *lower,
 309                           struct dentry *upper)
 310 {
 311         const struct ovl_fh *fh = NULL;
 312         int err;
 313
 314         /*
 315          * When lower layer doesn't support export operations store a 'null' fh,
 316          * so we can use the overlay.origin xattr to distignuish between a copy
 317          * up and a pure upper inode.
 318          */
 319         if (ovl_can_decode_fh(lower->d_sb)) {
 320                 fh = ovl_encode_fh(lower, false);
 321                 if (IS_ERR(fh))
 322                         return PTR_ERR(fh);
 323         }
 324
 325         /*
 326          * Do not fail when upper doesn't support xattrs.
 327          */
 328         err = ovl_check_setxattr(dentry, upper, OVL_XATTR_ORIGIN, fh,
 329                                  fh ? fh->len : 0, 0);
 330         kfree(fh);
 331
 332         return err;
 333 }
 334
 335 struct ovl_copy_up_ctx {
 336         struct dentry *parent;
 337         struct dentry *dentry;
 338         struct path lowerpath;
 339         struct kstat stat;
 340         struct kstat pstat;
 341         const char *link;
 342         struct dentry *destdir;
 343         struct qstr destname;
 344         struct dentry *workdir;
 345         bool tmpfile;
 346         bool origin;
 347 };
 348
 349 static int ovl_link_up(struct ovl_copy_up_ctx *c)
 350 {
 351         int err;
 352         struct dentry *upper;
 353         struct dentry *upperdir = ovl_dentry_upper(c->parent);
 354         struct inode *udir = d_inode(upperdir);
 355
 356         /* Mark parent "impure" because it may now contain non-pure upper */
 357         err = ovl_set_impure(c->parent, upperdir);
 358         if (err)
 359                 return err;
 360
 361         err = ovl_set_nlink_lower(c->dentry);
 362         if (err)
 363                 return err;
 364
 365         inode_lock_nested(udir, I_MUTEX_PARENT);
 366         upper = lookup_one_len(c->dentry->d_name.name, upperdir,
 367                                c->dentry->d_name.len);
 368         err = PTR_ERR(upper);
 369         if (!IS_ERR(upper)) {
 370                 err = ovl_do_link(ovl_dentry_upper(c->dentry), udir, upper,
 371                                   true);
 372                 dput(upper);
 373
 374                 if (!err) {
 375                         /* Restore timestamps on parent (best effort) */
 376                         ovl_set_timestamps(upperdir, &c->pstat);
 377                         ovl_dentry_set_upper_alias(c->dentry);
 378                 }
 379         }
 380         inode_unlock(udir);
 381         ovl_set_nlink_upper(c->dentry);
 382
 383         return err;
 384 }
 385
 386 static int ovl_install_temp(struct ovl_copy_up_ctx *c, struct dentry *temp,
 387                             struct dentry **newdentry)
 388 {
 389         int err;
 390         struct dentry *upper;
 391         struct inode *udir = d_inode(c->destdir);
 392
 393         upper = lookup_one_len(c->destname.name, c->destdir, c->destname.len);
 394         if (IS_ERR(upper))
 395                 return PTR_ERR(upper);
 396
 397         if (c->tmpfile)
 398                 err = ovl_do_link(temp, udir, upper, true);
 399         else
 400                 err = ovl_do_rename(d_inode(c->workdir), temp, udir, upper, 0);
 401
 402         if (!err)
 403                 *newdentry = dget(c->tmpfile ? upper : temp);
 404         dput(upper);
 405
 406         return err;
 407 }
 408
 409 static int ovl_get_tmpfile(struct ovl_copy_up_ctx *c, struct dentry **tempp)
 410 {
 411         int err;
 412         struct dentry *temp;
 413         const struct cred *old_creds = NULL;
 414         struct cred *new_creds = NULL;
 415         struct cattr cattr = {
 416                 /* Can't properly set mode on creation because of the umask */
 417                 .mode = c->stat.mode & S_IFMT,
 418                 .rdev = c->stat.rdev,
 419                 .link = c->link
 420         };
 421
 422         err = security_inode_copy_up(c->dentry, &new_creds);
 423         if (err < 0)
 424                 goto out;
 425
 426         if (new_creds)
 427                 old_creds = override_creds(new_creds);
 428
 429         if (c->tmpfile) {
 430                 temp = ovl_do_tmpfile(c->workdir, c->stat.mode);
 431                 if (IS_ERR(temp))
 432                         goto temp_err;
 433         } else {
 434                 temp = ovl_lookup_temp(c->workdir);
 435                 if (IS_ERR(temp))
 436                         goto temp_err;
 437
 438                 err = ovl_create_real(d_inode(c->workdir), temp, &cattr,
 439                                       NULL, true);
 440                 if (err) {
 441                         dput(temp);
 442                         goto out;
 443                 }
 444         }
 445         err = 0;
 446         *tempp = temp;
 447 out:
 448         if (new_creds) {
 449                 revert_creds(old_creds);
 450                 put_cred(new_creds);
 451         }
 452
 453         return err;
 454
 455 temp_err:
 456         err = PTR_ERR(temp);
 457         goto out;
 458 }
 459
 460 static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp)
 461 {
 462         int err;
 463
 464         if (S_ISREG(c->stat.mode)) {
 465                 struct path upperpath;
 466
 467                 ovl_path_upper(c->dentry, &upperpath);
 468                 BUG_ON(upperpath.dentry != NULL);
 469                 upperpath.dentry = temp;
 470
 471                 err = ovl_copy_up_data(&c->lowerpath, &upperpath, c->stat.size);
 472                 if (err)
 473                         return err;
 474         }
 475
 476         err = ovl_copy_xattr(c->lowerpath.dentry, temp);
 477         if (err)
 478                 return err;
 479
 480         inode_lock(temp->d_inode);
 481         err = ovl_set_attr(temp, &c->stat);
 482         inode_unlock(temp->d_inode);
 483         if (err)
 484                 return err;
 485
 486         /*
 487          * Store identifier of lower inode in upper inode xattr to
 488          * allow lookup of the copy up origin inode.
 489          *
 490          * Don't set origin when we are breaking the association with a lower
 491          * hard link.
 492          */
 493         if (c->origin) {
 494                 err = ovl_set_origin(c->dentry, c->lowerpath.dentry, temp);
 495                 if (err)
 496                         return err;
 497         }
 498
 499         return 0;
 500 }
 501
 502 static int ovl_copy_up_locked(struct ovl_copy_up_ctx *c)
 503 {
 504         struct inode *udir = c->destdir->d_inode;
 505         struct inode *inode;
 506         struct dentry *newdentry = NULL;
 507         struct dentry *temp = NULL;
 508         int err;
 509
 510         err = ovl_get_tmpfile(c, &temp);
 511         if (err)
 512                 goto out;
 513
 514         err = ovl_copy_up_inode(c, temp);
 515         if (err)
 516                 goto out_cleanup;
 517
 518         if (c->tmpfile) {
 519                 inode_lock_nested(udir, I_MUTEX_PARENT);
 520                 err = ovl_install_temp(c, temp, &newdentry);
 521                 inode_unlock(udir);
 522         } else {
 523                 err = ovl_install_temp(c, temp, &newdentry);
 524         }
 525         if (err)
 526                 goto out_cleanup;
 527
 528         inode = d_inode(c->dentry);
 529         ovl_inode_update(inode, newdentry);
 530         if (S_ISDIR(inode->i_mode))
 531                 ovl_set_flag(OVL_WHITEOUTS, inode);
 532
 533 out:
 534         dput(temp);
 535         return err;
 536
 537 out_cleanup:
 538         if (!c->tmpfile)
 539                 ovl_cleanup(d_inode(c->workdir), temp);
 540         goto out;
 541 }
 542
 543 /*
 544  * Copy up a single dentry
 545  *
 546  * All renames start with copy up of source if necessary.  The actual
 547  * rename will only proceed once the copy up was successful.  Copy up uses
 548  * upper parent i_mutex for exclusion.  Since rename can change d_parent it
 549  * is possible that the copy up will lock the old parent.  At that point
 550  * the file will have already been copied up anyway.
 551  */
 552 static int ovl_do_copy_up(struct ovl_copy_up_ctx *c)
 553 {
 554         int err;
 555         struct ovl_fs *ofs = c->dentry->d_sb->s_fs_info;
 556         bool indexed = false;
 557
 558         if (ovl_indexdir(c->dentry->d_sb) && !S_ISDIR(c->stat.mode) &&
 559             c->stat.nlink > 1)
 560                 indexed = true;
 561
 562         if (S_ISDIR(c->stat.mode) || c->stat.nlink == 1 || indexed)
 563                 c->origin = true;
 564
 565         if (indexed) {
 566                 c->destdir = ovl_indexdir(c->dentry->d_sb);
 567                 err = ovl_get_index_name(c->lowerpath.dentry, &c->destname);
 568                 if (err)
 569                         return err;
 570         } else {
 571                 /*
 572                  * Mark parent "impure" because it may now contain non-pure
 573                  * upper
 574                  */
 575                 err = ovl_set_impure(c->parent, c->destdir);
 576                 if (err)
 577                         return err;
 578         }
 579
 580         /* Should we copyup with O_TMPFILE or with workdir? */
 581         if (S_ISREG(c->stat.mode) && ofs->tmpfile) {
 582                 c->tmpfile = true;
 583                 err = ovl_copy_up_locked(c);
 584         } else {
 585                 err = ovl_lock_rename_workdir(c->workdir, c->destdir);
 586                 if (!err) {
 587                         err = ovl_copy_up_locked(c);
 588                         unlock_rename(c->workdir, c->destdir);
 589                 }
 590         }
 591
 592         if (indexed) {
 593                 if (!err)
 594                         ovl_set_flag(OVL_INDEX, d_inode(c->dentry));
 595                 kfree(c->destname.name);
 596         } else if (!err) {
 597                 struct inode *udir = d_inode(c->destdir);
 598
 599                 /* Restore timestamps on parent (best effort) */
 600                 inode_lock(udir);
 601                 ovl_set_timestamps(c->destdir, &c->pstat);
 602                 inode_unlock(udir);
 603
 604                 ovl_dentry_set_upper_alias(c->dentry);
 605         }
 606
 607         return err;
 608 }
 609
 610 static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
 611                            int flags)
 612 {
 613         int err;
 614         DEFINE_DELAYED_CALL(done);
 615         struct path parentpath;
 616         struct ovl_copy_up_ctx ctx = {
 617                 .parent = parent,
 618                 .dentry = dentry,
 619                 .workdir = ovl_workdir(dentry),
 620         };
 621
 622         if (WARN_ON(!ctx.workdir))
 623                 return -EROFS;
 624
 625         ovl_path_lower(dentry, &ctx.lowerpath);
 626         err = vfs_getattr(&ctx.lowerpath, &ctx.stat,
 627                           STATX_BASIC_STATS, AT_STATX_SYNC_AS_STAT);
 628         if (err)
 629                 return err;
 630
 631         ovl_path_upper(parent, &parentpath);
 632         ctx.destdir = parentpath.dentry;
 633         ctx.destname = dentry->d_name;
 634
 635         err = vfs_getattr(&parentpath, &ctx.pstat,
 636                           STATX_ATIME | STATX_MTIME, AT_STATX_SYNC_AS_STAT);
 637         if (err)
 638                 return err;
 639
 640         /* maybe truncate regular file. this has no effect on dirs */
 641         if (flags & O_TRUNC)
 642                 ctx.stat.size = 0;
 643
 644         if (S_ISLNK(ctx.stat.mode)) {
 645                 ctx.link = vfs_get_link(ctx.lowerpath.dentry, &done);
 646                 if (IS_ERR(ctx.link))
 647                         return PTR_ERR(ctx.link);
 648         }
 649         ovl_do_check_copy_up(ctx.lowerpath.dentry);
 650
 651         err = ovl_copy_up_start(dentry);
 652         /* err < 0: interrupted, err > 0: raced with another copy-up */
 653         if (unlikely(err)) {
 654                 if (err > 0)
 655                         err = 0;
 656         } else {
 657                 if (!ovl_dentry_upper(dentry))
 658                         err = ovl_do_copy_up(&ctx);
 659                 if (!err && !ovl_dentry_has_upper_alias(dentry))
 660                         err = ovl_link_up(&ctx);
 661                 ovl_copy_up_end(dentry);
 662         }
 663         do_delayed_call(&done);
 664
 665         return err;
 666 }
 667
 668 int ovl_copy_up_flags(struct dentry *dentry, int flags)
 669 {
 670         int err = 0;
 671         const struct cred *old_cred = ovl_override_creds(dentry->d_sb);
 672
 673         while (!err) {
 674                 struct dentry *next;
 675                 struct dentry *parent;
 676
 677                 /*
 678                  * Check if copy-up has happened as well as for upper alias (in
 679                  * case of hard links) is there.
 680                  *
 681                  * Both checks are lockless:
 682                  *  - false negatives: will recheck under oi->lock
 683                  *  - false positives:
 684                  *    + ovl_dentry_upper() uses memory barriers to ensure the
 685                  *      upper dentry is up-to-date
 686                  *    + ovl_dentry_has_upper_alias() relies on locking of
 687                  *      upper parent i_rwsem to prevent reordering copy-up
 688                  *      with rename.
 689                  */
 690                 if (ovl_dentry_upper(dentry) &&
 691                     ovl_dentry_has_upper_alias(dentry))
 692                         break;
 693
 694                 next = dget(dentry);
 695                 /* find the topmost dentry not yet copied up */
 696                 for (;;) {
 697                         parent = dget_parent(next);
 698
 699                         if (ovl_dentry_upper(parent))
 700                                 break;
 701
 702                         dput(next);
 703                         next = parent;
 704                 }
 705
 706                 err = ovl_copy_up_one(parent, next, flags);
 707
 708                 dput(parent);
 709                 dput(next);
 710         }
 711         revert_creds(old_cred);
 712
 713         return err;
 714 }
 715
 716 int ovl_copy_up(struct dentry *dentry)
 717 {
 718         return ovl_copy_up_flags(dentry, 0);
 719 }