1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (C) 2011 Novell Inc.
4 * Copyright (C) 2016 Red Hat, Inc.
8 #include <linux/cred.h>
9 #include <linux/ctype.h>
10 #include <linux/namei.h>
11 #include <linux/xattr.h>
12 #include <linux/ratelimit.h>
13 #include <linux/mount.h>
14 #include <linux/exportfs.h>
15 #include "overlayfs.h"
17 struct ovl_lookup_data {
18 struct super_block *sb;
28 static int ovl_check_redirect(struct dentry *dentry, struct ovl_lookup_data *d,
29 size_t prelen, const char *post)
34 buf = ovl_get_redirect_xattr(dentry, prelen + strlen(post));
35 if (IS_ERR_OR_NULL(buf))
40 * One of the ancestor path elements in an absolute path
41 * lookup in ovl_lookup_layer() could have been opaque and
42 * that will stop further lookup in lower layers (d->stop=true)
43 * But we have found an absolute redirect in decendant path
44 * element and that should force continue lookup in lower
45 * layers (reset d->stop).
49 res = strlen(buf) + 1;
50 memmove(buf + prelen, buf, res);
51 memcpy(buf, d->name.name, prelen);
57 d->name.name = d->redirect;
58 d->name.len = strlen(d->redirect);
63 static int ovl_acceptable(void *ctx, struct dentry *dentry)
66 * A non-dir origin may be disconnected, which is fine, because
67 * we only need it for its unique inode number.
69 if (!d_is_dir(dentry))
72 /* Don't decode a deleted empty directory */
73 if (d_unhashed(dentry))
76 /* Check if directory belongs to the layer we are decoding from */
77 return is_subdir(dentry, ((struct vfsmount *)ctx)->mnt_root);
81 * Check validity of an overlay file handle buffer.
83 * Return 0 for a valid file handle.
84 * Return -ENODATA for "origin unknown".
85 * Return <0 for an invalid file handle.
87 int ovl_check_fb_len(struct ovl_fb *fb, int fb_len)
89 if (fb_len < sizeof(struct ovl_fb) || fb_len < fb->len)
92 if (fb->magic != OVL_FH_MAGIC)
95 /* Treat larger version and unknown flags as "origin unknown" */
96 if (fb->version > OVL_FH_VERSION || fb->flags & ~OVL_FH_FLAG_ALL)
99 /* Treat endianness mismatch as "origin unknown" */
100 if (!(fb->flags & OVL_FH_FLAG_ANY_ENDIAN) &&
101 (fb->flags & OVL_FH_FLAG_BIG_ENDIAN) != OVL_FH_FLAG_CPU_ENDIAN)
107 static struct ovl_fh *ovl_get_fh(struct dentry *dentry, const char *name)
110 struct ovl_fh *fh = NULL;
112 res = vfs_getxattr(dentry, name, NULL, 0);
114 if (res == -ENODATA || res == -EOPNOTSUPP)
118 /* Zero size value means "copied up but origin unknown" */
122 fh = kzalloc(res + OVL_FH_WIRE_OFFSET, GFP_KERNEL);
124 return ERR_PTR(-ENOMEM);
126 res = vfs_getxattr(dentry, name, fh->buf, res);
130 err = ovl_check_fb_len(&fh->fb, res);
144 pr_warn_ratelimited("failed to get origin (%i)\n", res);
147 pr_warn_ratelimited("invalid origin (%*phN)\n", res, fh);
151 struct dentry *ovl_decode_real_fh(struct ovl_fh *fh, struct vfsmount *mnt,
158 * Make sure that the stored uuid matches the uuid of the lower
159 * layer where file handle will be decoded.
161 if (!uuid_equal(&fh->fb.uuid, &mnt->mnt_sb->s_uuid))
164 bytes = (fh->fb.len - offsetof(struct ovl_fb, fid));
165 real = exportfs_decode_fh(mnt, (struct fid *)fh->fb.fid,
166 bytes >> 2, (int)fh->fb.type,
167 connected ? ovl_acceptable : NULL, mnt);
170 * Treat stale file handle to lower file as "origin unknown".
171 * upper file handle could become stale when upper file is
172 * unlinked and this information is needed to handle stale
173 * index entries correctly.
175 if (real == ERR_PTR(-ESTALE) &&
176 !(fh->fb.flags & OVL_FH_FLAG_PATH_UPPER))
181 if (ovl_dentry_weird(real)) {
189 static bool ovl_is_opaquedir(struct dentry *dentry)
191 return ovl_check_dir_xattr(dentry, OVL_XATTR_OPAQUE);
194 static int ovl_lookup_single(struct dentry *base, struct ovl_lookup_data *d,
195 const char *name, unsigned int namelen,
196 size_t prelen, const char *post,
201 bool last_element = !post[0];
203 this = lookup_positive_unlocked(name, base, namelen);
207 if (err == -ENOENT || err == -ENAMETOOLONG)
212 if (ovl_dentry_weird(this)) {
213 /* Don't support traversing automounts and other weirdness */
217 if (ovl_is_whiteout(this)) {
218 d->stop = d->opaque = true;
222 * This dentry should be a regular file if previous layer lookup
223 * found a metacopy dentry.
225 if (last_element && d->metacopy && !d_is_reg(this)) {
229 if (!d_can_lookup(this)) {
230 if (d->is_dir || !last_element) {
234 err = ovl_check_metacopy_xattr(this);
239 d->stop = !d->metacopy;
240 if (!d->metacopy || d->last)
243 if (ovl_lookup_trap_inode(d->sb, this)) {
244 /* Caught in a trap of overlapping layers */
254 if (ovl_is_opaquedir(this)) {
261 err = ovl_check_redirect(this, d, prelen, post);
278 static int ovl_lookup_layer(struct dentry *base, struct ovl_lookup_data *d,
281 /* Counting down from the end, since the prefix can change */
282 size_t rem = d->name.len - 1;
283 struct dentry *dentry = NULL;
286 if (d->name.name[0] != '/')
287 return ovl_lookup_single(base, d, d->name.name, d->name.len,
290 while (!IS_ERR_OR_NULL(base) && d_can_lookup(base)) {
291 const char *s = d->name.name + d->name.len - rem;
292 const char *next = strchrnul(s, '/');
293 size_t thislen = next - s;
296 /* Verify we did not go off the rails */
297 if (WARN_ON(s[-1] != '/'))
300 err = ovl_lookup_single(base, d, s, thislen,
301 d->name.len - rem, next, &base);
311 if (WARN_ON(rem >= d->name.len))
319 int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, bool connected,
320 struct dentry *upperdentry, struct ovl_path **stackp)
322 struct dentry *origin = NULL;
325 for (i = 1; i < ofs->numlayer; i++) {
327 * If lower fs uuid is not unique among lower fs we cannot match
330 if (ofs->layers[i].fsid &&
331 ofs->layers[i].fs->bad_uuid)
334 origin = ovl_decode_real_fh(fh, ofs->layers[i].mnt,
342 else if (IS_ERR(origin))
343 return PTR_ERR(origin);
345 if (upperdentry && !ovl_is_whiteout(upperdentry) &&
346 ((d_inode(origin)->i_mode ^ d_inode(upperdentry)->i_mode) & S_IFMT))
350 *stackp = kmalloc(sizeof(struct ovl_path), GFP_KERNEL);
355 **stackp = (struct ovl_path){
357 .layer = &ofs->layers[i]
363 pr_warn_ratelimited("invalid origin (%pd2, ftype=%x, origin ftype=%x).\n",
364 upperdentry, d_inode(upperdentry)->i_mode & S_IFMT,
365 d_inode(origin)->i_mode & S_IFMT);
370 static int ovl_check_origin(struct ovl_fs *ofs, struct dentry *upperdentry,
371 struct ovl_path **stackp, unsigned int *ctrp)
373 struct ovl_fh *fh = ovl_get_fh(upperdentry, OVL_XATTR_ORIGIN);
376 if (IS_ERR_OR_NULL(fh))
379 err = ovl_check_origin_fh(ofs, fh, false, upperdentry, stackp);
396 * Verify that @fh matches the file handle stored in xattr @name.
397 * Return 0 on match, -ESTALE on mismatch, < 0 on error.
399 static int ovl_verify_fh(struct dentry *dentry, const char *name,
400 const struct ovl_fh *fh)
402 struct ovl_fh *ofh = ovl_get_fh(dentry, name);
411 if (fh->fb.len != ofh->fb.len || memcmp(&fh->fb, &ofh->fb, fh->fb.len))
419 * Verify that @real dentry matches the file handle stored in xattr @name.
421 * If @set is true and there is no stored file handle, encode @real and store
422 * file handle in xattr @name.
424 * Return 0 on match, -ESTALE on mismatch, -ENODATA on no xattr, < 0 on error.
426 int ovl_verify_set_fh(struct dentry *dentry, const char *name,
427 struct dentry *real, bool is_upper, bool set)
433 fh = ovl_encode_real_fh(real, is_upper);
440 err = ovl_verify_fh(dentry, name, fh);
441 if (set && err == -ENODATA)
442 err = ovl_do_setxattr(dentry, name, fh->buf, fh->fb.len, 0);
451 inode = d_inode(real);
452 pr_warn_ratelimited("failed to verify %s (%pd2, ino=%lu, err=%i)\n",
453 is_upper ? "upper" : "origin", real,
454 inode ? inode->i_ino : 0, err);
458 /* Get upper dentry from index */
459 struct dentry *ovl_index_upper(struct ovl_fs *ofs, struct dentry *index)
462 struct dentry *upper;
464 if (!d_is_dir(index))
467 fh = ovl_get_fh(index, OVL_XATTR_UPPER);
468 if (IS_ERR_OR_NULL(fh))
471 upper = ovl_decode_real_fh(fh, ofs->upper_mnt, true);
474 if (IS_ERR_OR_NULL(upper))
475 return upper ?: ERR_PTR(-ESTALE);
477 if (!d_is_dir(upper)) {
478 pr_warn_ratelimited("invalid index upper (%pd2, upper=%pd2).\n",
481 return ERR_PTR(-EIO);
487 /* Is this a leftover from create/whiteout of directory index entry? */
488 static bool ovl_is_temp_index(struct dentry *index)
490 return index->d_name.name[0] == '#';
494 * Verify that an index entry name matches the origin file handle stored in
495 * OVL_XATTR_ORIGIN and that origin file handle can be decoded to lower path.
496 * Return 0 on match, -ESTALE on mismatch or stale origin, < 0 on error.
498 int ovl_verify_index(struct ovl_fs *ofs, struct dentry *index)
500 struct ovl_fh *fh = NULL;
502 struct ovl_path origin = { };
503 struct ovl_path *stack = &origin;
504 struct dentry *upper = NULL;
510 /* Cleanup leftover from index create/cleanup attempt */
512 if (ovl_is_temp_index(index))
516 if (index->d_name.len < sizeof(struct ovl_fb)*2)
520 len = index->d_name.len / 2;
521 fh = kzalloc(len + OVL_FH_WIRE_OFFSET, GFP_KERNEL);
526 if (hex2bin(fh->buf, index->d_name.name, len))
529 err = ovl_check_fb_len(&fh->fb, len);
534 * Whiteout index entries are used as an indication that an exported
535 * overlay file handle should be treated as stale (i.e. after unlink
536 * of the overlay inode). These entries contain no origin xattr.
538 if (ovl_is_whiteout(index))
542 * Verifying directory index entries are not stale is expensive, so
543 * only verify stale dir index if NFS export is enabled.
545 if (d_is_dir(index) && !ofs->config.nfs_export)
549 * Directory index entries should have 'upper' xattr pointing to the
550 * real upper dir. Non-dir index entries are hardlinks to the upper
551 * real inode. For non-dir index, we can read the copy up origin xattr
552 * directly from the index dentry, but for dir index we first need to
553 * decode the upper directory.
555 upper = ovl_index_upper(ofs, index);
556 if (IS_ERR_OR_NULL(upper)) {
557 err = PTR_ERR(upper);
559 * Directory index entries with no 'upper' xattr need to be
560 * removed. When dir index entry has a stale 'upper' xattr,
561 * we assume that upper dir was removed and we treat the dir
562 * index as orphan entry that needs to be whited out.
571 err = ovl_verify_fh(upper, OVL_XATTR_ORIGIN, fh);
576 /* Check if non-dir index is orphan and don't warn before cleaning it */
577 if (!d_is_dir(index) && d_inode(index)->i_nlink == 1) {
578 err = ovl_check_origin_fh(ofs, fh, false, index, &stack);
582 if (ovl_get_nlink(origin.dentry, index, 0) == 0)
592 pr_warn_ratelimited("failed to verify index (%pd2, ftype=%x, err=%i)\n",
593 index, d_inode(index)->i_mode & S_IFMT, err);
597 pr_warn_ratelimited("orphan index entry (%pd2, ftype=%x, nlink=%u)\n",
598 index, d_inode(index)->i_mode & S_IFMT,
599 d_inode(index)->i_nlink);
604 static int ovl_get_index_name_fh(struct ovl_fh *fh, struct qstr *name)
608 n = kcalloc(fh->fb.len, 2, GFP_KERNEL);
612 s = bin2hex(n, fh->buf, fh->fb.len);
613 *name = (struct qstr) QSTR_INIT(n, s - n);
620 * Lookup in indexdir for the index entry of a lower real inode or a copy up
621 * origin inode. The index entry name is the hex representation of the lower
624 * If the index dentry in negative, then either no lower aliases have been
625 * copied up yet, or aliases have been copied up in older kernels and are
628 * If the index dentry for a copy up origin inode is positive, but points
629 * to an inode different than the upper inode, then either the upper inode
630 * has been copied up and not indexed or it was indexed, but since then
631 * index dir was cleared. Either way, that index cannot be used to indentify
634 int ovl_get_index_name(struct dentry *origin, struct qstr *name)
639 fh = ovl_encode_real_fh(origin, false);
643 err = ovl_get_index_name_fh(fh, name);
649 /* Lookup index by file handle for NFS export */
650 struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh)
652 struct dentry *index;
656 err = ovl_get_index_name_fh(fh, &name);
660 index = lookup_positive_unlocked(name.name, ofs->indexdir, name.len);
663 if (PTR_ERR(index) == -ENOENT)
668 if (ovl_is_whiteout(index))
670 else if (ovl_dentry_weird(index))
679 struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper,
680 struct dentry *origin, bool verify)
682 struct dentry *index;
685 bool is_dir = d_is_dir(origin);
688 err = ovl_get_index_name(origin, &name);
692 index = lookup_positive_unlocked(name.name, ofs->indexdir, name.len);
694 err = PTR_ERR(index);
695 if (err == -ENOENT) {
699 pr_warn_ratelimited("failed inode index lookup (ino=%lu, key=%.*s, err=%i);\n"
700 "overlayfs: mount with '-o index=off' to disable inodes index.\n",
701 d_inode(origin)->i_ino, name.len, name.name,
706 inode = d_inode(index);
707 if (ovl_is_whiteout(index) && !verify) {
709 * When index lookup is called with !verify for decoding an
710 * overlay file handle, a whiteout index implies that decode
711 * should treat file handle as stale and no need to print a
715 index = ERR_PTR(-ESTALE);
717 } else if (ovl_dentry_weird(index) || ovl_is_whiteout(index) ||
718 ((inode->i_mode ^ d_inode(origin)->i_mode) & S_IFMT)) {
720 * Index should always be of the same file type as origin
721 * except for the case of a whiteout index. A whiteout
722 * index should only exist if all lower aliases have been
723 * unlinked, which means that finding a lower origin on lookup
724 * whose index is a whiteout should be treated as an error.
726 pr_warn_ratelimited("bad index found (index=%pd2, ftype=%x, origin ftype=%x).\n",
727 index, d_inode(index)->i_mode & S_IFMT,
728 d_inode(origin)->i_mode & S_IFMT);
730 } else if (is_dir && verify) {
732 pr_warn_ratelimited("suspected uncovered redirected dir found (origin=%pd2, index=%pd2).\n",
737 /* Verify that dir index 'upper' xattr points to upper dir */
738 err = ovl_verify_upper(index, upper, false);
740 if (err == -ESTALE) {
741 pr_warn_ratelimited("suspected multiply redirected dir found (upper=%pd2, origin=%pd2, index=%pd2).\n",
742 upper, origin, index);
746 } else if (upper && d_inode(upper) != inode) {
760 index = ERR_PTR(-EIO);
765 * Returns next layer in stack starting from top.
766 * Returns -1 if this is the last layer.
768 int ovl_path_next(int idx, struct dentry *dentry, struct path *path)
770 struct ovl_entry *oe = dentry->d_fsdata;
774 ovl_path_upper(dentry, path);
776 return oe->numlower ? 1 : -1;
779 BUG_ON(idx > oe->numlower);
780 path->dentry = oe->lowerstack[idx - 1].dentry;
781 path->mnt = oe->lowerstack[idx - 1].layer->mnt;
783 return (idx < oe->numlower) ? idx + 1 : -1;
786 /* Fix missing 'origin' xattr */
787 static int ovl_fix_origin(struct dentry *dentry, struct dentry *lower,
788 struct dentry *upper)
792 if (ovl_check_origin_xattr(upper))
795 err = ovl_want_write(dentry);
799 err = ovl_set_origin(dentry, lower, upper);
801 err = ovl_set_impure(dentry->d_parent, upper->d_parent);
803 ovl_drop_write(dentry);
807 struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
810 struct ovl_entry *oe;
811 const struct cred *old_cred;
812 struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
813 struct ovl_entry *poe = dentry->d_parent->d_fsdata;
814 struct ovl_entry *roe = dentry->d_sb->s_root->d_fsdata;
815 struct ovl_path *stack = NULL, *origin_path = NULL;
816 struct dentry *upperdir, *upperdentry = NULL;
817 struct dentry *origin = NULL;
818 struct dentry *index = NULL;
819 unsigned int ctr = 0;
820 struct inode *inode = NULL;
821 bool upperopaque = false;
822 char *upperredirect = NULL;
826 bool metacopy = false;
827 struct ovl_lookup_data d = {
829 .name = dentry->d_name,
833 .last = ofs->config.redirect_follow ? false : !poe->numlower,
838 if (dentry->d_name.len > ofs->namelen)
839 return ERR_PTR(-ENAMETOOLONG);
841 old_cred = ovl_override_creds(dentry->d_sb);
842 upperdir = ovl_dentry_upper(dentry->d_parent);
844 err = ovl_lookup_layer(upperdir, &d, &upperdentry);
848 if (upperdentry && unlikely(ovl_dentry_remote(upperdentry))) {
853 if (upperdentry && !d.is_dir) {
854 unsigned int origin_ctr = 0;
857 * Lookup copy up origin by decoding origin file handle.
858 * We may get a disconnected dentry, which is fine,
859 * because we only need to hold the origin inode in
860 * cache and use its inode number. We may even get a
861 * connected dentry, that is not under any of the lower
862 * layers root. That is also fine for using it's inode
863 * number - it's the same as if we held a reference
864 * to a dentry in lower layer that was moved under us.
866 err = ovl_check_origin(ofs, upperdentry, &origin_path,
877 upperredirect = kstrdup(d.redirect, GFP_KERNEL);
880 if (d.redirect[0] == '/')
883 upperopaque = d.opaque;
886 if (!d.stop && poe->numlower) {
888 stack = kcalloc(ofs->numlayer - 1, sizeof(struct ovl_path),
894 for (i = 0; !d.stop && i < poe->numlower; i++) {
895 struct ovl_path lower = poe->lowerstack[i];
897 if (!ofs->config.redirect_follow)
898 d.last = i == poe->numlower - 1;
900 d.last = lower.layer->idx == roe->numlower;
902 err = ovl_lookup_layer(lower.dentry, &d, &this);
910 * If no origin fh is stored in upper of a merge dir, store fh
911 * of lower dir and set upper parent "impure".
913 if (upperdentry && !ctr && !ofs->noxattr && d.is_dir) {
914 err = ovl_fix_origin(dentry, this, upperdentry);
922 * When "verify_lower" feature is enabled, do not merge with a
923 * lower dir that does not match a stored origin xattr. In any
924 * case, only verified origin is used for index lookup.
926 * For non-dir dentry, if index=on, then ensure origin
927 * matches the dentry found using path based lookup,
928 * otherwise error out.
930 if (upperdentry && !ctr &&
931 ((d.is_dir && ovl_verify_lower(dentry->d_sb)) ||
932 (!d.is_dir && ofs->config.index && origin_path))) {
933 err = ovl_verify_origin(upperdentry, this, false);
946 * Do not store intermediate metacopy dentries in chain,
947 * except top most lower metacopy dentry
949 if (d.metacopy && ctr) {
954 stack[ctr].dentry = this;
955 stack[ctr].layer = lower.layer;
959 * Following redirects can have security consequences: it's like
960 * a symlink into the lower layer without the permission checks.
961 * This is only a problem if the upper layer is untrusted (e.g
962 * comes from an USB drive). This can allow a non-readable file
963 * or directory to become readable.
965 * Only following redirects when redirects are enabled disables
966 * this attack vector when not necessary.
969 if (d.redirect && !ofs->config.redirect_follow) {
970 pr_warn_ratelimited("refusing to follow redirect for (%pd2)\n",
978 if (d.redirect && d.redirect[0] == '/' && poe != roe) {
980 /* Find the current layer on the root dentry */
981 i = lower.layer->idx - 1;
987 * Found a metacopy dentry but did not find corresponding
996 if (!ofs->config.metacopy) {
997 pr_warn_ratelimited("refusing to follow metacopy origin for (%pd2)\n",
1001 } else if (!d.is_dir && upperdentry && !ctr && origin_path) {
1002 if (WARN_ON(stack != NULL)) {
1006 stack = origin_path;
1012 * Lookup index by lower inode and verify it matches upper inode.
1013 * We only trust dir index if we verified that lower dir matches
1014 * origin, otherwise dir index entries may be inconsistent and we
1017 * For non-dir upper metacopy dentry, we already set "origin" if we
1018 * verified that lower matched upper origin. If upper origin was
1019 * not present (because lower layer did not support fh encode/decode),
1020 * or indexing is not enabled, do not set "origin" and skip looking up
1021 * index. This case should be handled in same way as a non-dir upper
1022 * without ORIGIN is handled.
1024 * Always lookup index of non-dir non-metacopy and non-upper.
1026 if (ctr && (!upperdentry || (!d.is_dir && !metacopy)))
1027 origin = stack[0].dentry;
1029 if (origin && ovl_indexdir(dentry->d_sb) &&
1030 (!d.is_dir || ovl_index_all(dentry->d_sb))) {
1031 index = ovl_lookup_index(ofs, upperdentry, origin, true);
1032 if (IS_ERR(index)) {
1033 err = PTR_ERR(index);
1039 oe = ovl_alloc_entry(ctr);
1044 memcpy(oe->lowerstack, stack, sizeof(struct ovl_path) * ctr);
1045 dentry->d_fsdata = oe;
1048 ovl_dentry_set_opaque(dentry);
1051 ovl_dentry_set_upper_alias(dentry);
1053 upperdentry = dget(index);
1054 upperredirect = ovl_get_redirect_xattr(upperdentry, 0);
1055 if (IS_ERR(upperredirect)) {
1056 err = PTR_ERR(upperredirect);
1057 upperredirect = NULL;
1062 if (upperdentry || ctr) {
1063 struct ovl_inode_params oip = {
1064 .upperdentry = upperdentry,
1068 .redirect = upperredirect,
1069 .lowerdata = (ctr > 1 && !d.is_dir) ?
1070 stack[ctr - 1].dentry : NULL,
1073 inode = ovl_get_inode(dentry->d_sb, &oip);
1074 err = PTR_ERR(inode);
1079 revert_creds(old_cred);
1081 dput(origin_path->dentry);
1087 return d_splice_alias(inode, dentry);
1090 dentry->d_fsdata = NULL;
1094 for (i = 0; i < ctr; i++)
1095 dput(stack[i].dentry);
1099 dput(origin_path->dentry);
1103 kfree(upperredirect);
1106 revert_creds(old_cred);
1107 return ERR_PTR(err);
1110 bool ovl_lower_positive(struct dentry *dentry)
1112 struct ovl_entry *poe = dentry->d_parent->d_fsdata;
1113 const struct qstr *name = &dentry->d_name;
1114 const struct cred *old_cred;
1116 bool positive = false;
1120 * If dentry is negative, then lower is positive iff this is a
1123 if (!dentry->d_inode)
1124 return ovl_dentry_is_opaque(dentry);
1126 /* Negative upper -> positive lower */
1127 if (!ovl_dentry_upper(dentry))
1130 old_cred = ovl_override_creds(dentry->d_sb);
1131 /* Positive upper -> have to look up lower to see whether it exists */
1132 for (i = 0; !done && !positive && i < poe->numlower; i++) {
1133 struct dentry *this;
1134 struct dentry *lowerdir = poe->lowerstack[i].dentry;
1136 this = lookup_positive_unlocked(name->name, lowerdir,
1139 switch (PTR_ERR(this)) {
1146 * Assume something is there, we just couldn't
1153 positive = !ovl_is_whiteout(this);
1158 revert_creds(old_cred);