[Feature]add MT2731_MP2_MR2_SVN388 baseline version
Change-Id: Ief04314834b31e27effab435d3ca8ba33b499059
diff --git a/src/kernel/linux/v4.14/fs/overlayfs/namei.c b/src/kernel/linux/v4.14/fs/overlayfs/namei.c
new file mode 100644
index 0000000..8442f98
--- /dev/null
+++ b/src/kernel/linux/v4.14/fs/overlayfs/namei.c
@@ -0,0 +1,809 @@
+/*
+ * Copyright (C) 2011 Novell Inc.
+ * Copyright (C) 2016 Red Hat, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/fs.h>
+#include <linux/cred.h>
+#include <linux/namei.h>
+#include <linux/xattr.h>
+#include <linux/ratelimit.h>
+#include <linux/mount.h>
+#include <linux/exportfs.h>
+#include "overlayfs.h"
+#include "ovl_entry.h"
+
+struct ovl_lookup_data {
+ struct qstr name;
+ bool is_dir;
+ bool opaque;
+ bool stop;
+ bool last;
+ char *redirect;
+};
+
+static int ovl_check_redirect(struct dentry *dentry, struct ovl_lookup_data *d,
+ size_t prelen, const char *post)
+{
+ int res;
+ char *s, *next, *buf = NULL;
+
+ res = vfs_getxattr(dentry, OVL_XATTR_REDIRECT, NULL, 0);
+ if (res < 0) {
+ if (res == -ENODATA || res == -EOPNOTSUPP)
+ return 0;
+ goto fail;
+ }
+ buf = kzalloc(prelen + res + strlen(post) + 1, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ if (res == 0)
+ goto invalid;
+
+ res = vfs_getxattr(dentry, OVL_XATTR_REDIRECT, buf, res);
+ if (res < 0)
+ goto fail;
+ if (res == 0)
+ goto invalid;
+ if (buf[0] == '/') {
+ for (s = buf; *s++ == '/'; s = next) {
+ next = strchrnul(s, '/');
+ if (s == next)
+ goto invalid;
+ }
+ /*
+ * One of the ancestor path elements in an absolute path
+ * lookup in ovl_lookup_layer() could have been opaque and
+ * that will stop further lookup in lower layers (d->stop=true)
+ * But we have found an absolute redirect in decendant path
+ * element and that should force continue lookup in lower
+ * layers (reset d->stop).
+ */
+ d->stop = false;
+ } else {
+ if (strchr(buf, '/') != NULL)
+ goto invalid;
+
+ memmove(buf + prelen, buf, res);
+ memcpy(buf, d->name.name, prelen);
+ }
+
+ strcat(buf, post);
+ kfree(d->redirect);
+ d->redirect = buf;
+ d->name.name = d->redirect;
+ d->name.len = strlen(d->redirect);
+
+ return 0;
+
+err_free:
+ kfree(buf);
+ return 0;
+fail:
+ pr_warn_ratelimited("overlayfs: failed to get redirect (%i)\n", res);
+ goto err_free;
+invalid:
+ pr_warn_ratelimited("overlayfs: invalid redirect (%s)\n", buf);
+ goto err_free;
+}
+
+static int ovl_acceptable(void *ctx, struct dentry *dentry)
+{
+ return 1;
+}
+
+static struct ovl_fh *ovl_get_origin_fh(struct dentry *dentry)
+{
+ int res;
+ struct ovl_fh *fh = NULL;
+
+ res = vfs_getxattr(dentry, OVL_XATTR_ORIGIN, NULL, 0);
+ if (res < 0) {
+ if (res == -ENODATA || res == -EOPNOTSUPP)
+ return NULL;
+ goto fail;
+ }
+ /* Zero size value means "copied up but origin unknown" */
+ if (res == 0)
+ return NULL;
+
+ fh = kzalloc(res, GFP_KERNEL);
+ if (!fh)
+ return ERR_PTR(-ENOMEM);
+
+ res = vfs_getxattr(dentry, OVL_XATTR_ORIGIN, fh, res);
+ if (res < 0)
+ goto fail;
+
+ if (res < sizeof(struct ovl_fh) || res < fh->len)
+ goto invalid;
+
+ if (fh->magic != OVL_FH_MAGIC)
+ goto invalid;
+
+ /* Treat larger version and unknown flags as "origin unknown" */
+ if (fh->version > OVL_FH_VERSION || fh->flags & ~OVL_FH_FLAG_ALL)
+ goto out;
+
+ /* Treat endianness mismatch as "origin unknown" */
+ if (!(fh->flags & OVL_FH_FLAG_ANY_ENDIAN) &&
+ (fh->flags & OVL_FH_FLAG_BIG_ENDIAN) != OVL_FH_FLAG_CPU_ENDIAN)
+ goto out;
+
+ return fh;
+
+out:
+ kfree(fh);
+ return NULL;
+
+fail:
+ pr_warn_ratelimited("overlayfs: failed to get origin (%i)\n", res);
+ goto out;
+invalid:
+ pr_warn_ratelimited("overlayfs: invalid origin (%*phN)\n", res, fh);
+ goto out;
+}
+
+static struct dentry *ovl_get_origin(struct dentry *dentry,
+ struct vfsmount *mnt)
+{
+ struct dentry *origin = NULL;
+ struct ovl_fh *fh = ovl_get_origin_fh(dentry);
+ int bytes;
+
+ if (IS_ERR_OR_NULL(fh))
+ return (struct dentry *)fh;
+
+ /*
+ * Make sure that the stored uuid matches the uuid of the lower
+ * layer where file handle will be decoded.
+ */
+ if (!uuid_equal(&fh->uuid, &mnt->mnt_sb->s_uuid))
+ goto out;
+
+ bytes = (fh->len - offsetof(struct ovl_fh, fid));
+ origin = exportfs_decode_fh(mnt, (struct fid *)fh->fid,
+ bytes >> 2, (int)fh->type,
+ ovl_acceptable, NULL);
+ if (IS_ERR(origin)) {
+ /* Treat stale file handle as "origin unknown" */
+ if (origin == ERR_PTR(-ESTALE))
+ origin = NULL;
+ goto out;
+ }
+
+ if (ovl_dentry_weird(origin) ||
+ ((d_inode(origin)->i_mode ^ d_inode(dentry)->i_mode) & S_IFMT))
+ goto invalid;
+
+out:
+ kfree(fh);
+ return origin;
+
+invalid:
+ pr_warn_ratelimited("overlayfs: invalid origin (%pd2)\n", origin);
+ dput(origin);
+ origin = NULL;
+ goto out;
+}
+
+static bool ovl_is_opaquedir(struct dentry *dentry)
+{
+ return ovl_check_dir_xattr(dentry, OVL_XATTR_OPAQUE);
+}
+
+static int ovl_lookup_single(struct dentry *base, struct ovl_lookup_data *d,
+ const char *name, unsigned int namelen,
+ size_t prelen, const char *post,
+ struct dentry **ret)
+{
+ struct dentry *this;
+ int err;
+
+ this = lookup_one_len_unlocked(name, base, namelen);
+ if (IS_ERR(this)) {
+ err = PTR_ERR(this);
+ this = NULL;
+ if (err == -ENOENT || err == -ENAMETOOLONG)
+ goto out;
+ goto out_err;
+ }
+ if (!this->d_inode)
+ goto put_and_out;
+
+ if (ovl_dentry_weird(this)) {
+ /* Don't support traversing automounts and other weirdness */
+ err = -EREMOTE;
+ goto out_err;
+ }
+ if (ovl_is_whiteout(this)) {
+ d->stop = d->opaque = true;
+ goto put_and_out;
+ }
+ if (!d_can_lookup(this)) {
+ d->stop = true;
+ if (d->is_dir)
+ goto put_and_out;
+ goto out;
+ }
+ d->is_dir = true;
+ if (!d->last && ovl_is_opaquedir(this)) {
+ d->stop = d->opaque = true;
+ goto out;
+ }
+ err = ovl_check_redirect(this, d, prelen, post);
+ if (err)
+ goto out_err;
+out:
+ *ret = this;
+ return 0;
+
+put_and_out:
+ dput(this);
+ this = NULL;
+ goto out;
+
+out_err:
+ dput(this);
+ return err;
+}
+
+static int ovl_lookup_layer(struct dentry *base, struct ovl_lookup_data *d,
+ struct dentry **ret)
+{
+ /* Counting down from the end, since the prefix can change */
+ size_t rem = d->name.len - 1;
+ struct dentry *dentry = NULL;
+ int err;
+
+ if (d->name.name[0] != '/')
+ return ovl_lookup_single(base, d, d->name.name, d->name.len,
+ 0, "", ret);
+
+ while (!IS_ERR_OR_NULL(base) && d_can_lookup(base)) {
+ const char *s = d->name.name + d->name.len - rem;
+ const char *next = strchrnul(s, '/');
+ size_t thislen = next - s;
+ bool end = !next[0];
+
+ /* Verify we did not go off the rails */
+ if (WARN_ON(s[-1] != '/'))
+ return -EIO;
+
+ err = ovl_lookup_single(base, d, s, thislen,
+ d->name.len - rem, next, &base);
+ dput(dentry);
+ if (err)
+ return err;
+ dentry = base;
+ if (end)
+ break;
+
+ rem -= thislen + 1;
+
+ if (WARN_ON(rem >= d->name.len))
+ return -EIO;
+ }
+ *ret = dentry;
+ return 0;
+}
+
+
+static int ovl_check_origin(struct dentry *upperdentry,
+ struct path *lowerstack, unsigned int numlower,
+ struct path **stackp, unsigned int *ctrp)
+{
+ struct vfsmount *mnt;
+ struct dentry *origin = NULL;
+ int i;
+
+
+ for (i = 0; i < numlower; i++) {
+ mnt = lowerstack[i].mnt;
+ origin = ovl_get_origin(upperdentry, mnt);
+ if (IS_ERR(origin))
+ return PTR_ERR(origin);
+
+ if (origin)
+ break;
+ }
+
+ if (!origin)
+ return 0;
+
+ BUG_ON(*ctrp);
+ if (!*stackp)
+ *stackp = kmalloc(sizeof(struct path), GFP_KERNEL);
+ if (!*stackp) {
+ dput(origin);
+ return -ENOMEM;
+ }
+ **stackp = (struct path) { .dentry = origin, .mnt = mnt };
+ *ctrp = 1;
+
+ return 0;
+}
+
+/*
+ * Verify that @fh matches the origin file handle stored in OVL_XATTR_ORIGIN.
+ * Return 0 on match, -ESTALE on mismatch, < 0 on error.
+ */
+static int ovl_verify_origin_fh(struct dentry *dentry, const struct ovl_fh *fh)
+{
+ struct ovl_fh *ofh = ovl_get_origin_fh(dentry);
+ int err = 0;
+
+ if (!ofh)
+ return -ENODATA;
+
+ if (IS_ERR(ofh))
+ return PTR_ERR(ofh);
+
+ if (fh->len != ofh->len || memcmp(fh, ofh, fh->len))
+ err = -ESTALE;
+
+ kfree(ofh);
+ return err;
+}
+
+/*
+ * Verify that an inode matches the origin file handle stored in upper inode.
+ *
+ * If @set is true and there is no stored file handle, encode and store origin
+ * file handle in OVL_XATTR_ORIGIN.
+ *
+ * Return 0 on match, -ESTALE on mismatch, < 0 on error.
+ */
+int ovl_verify_origin(struct dentry *dentry, struct vfsmount *mnt,
+ struct dentry *origin, bool is_upper, bool set)
+{
+ struct inode *inode;
+ struct ovl_fh *fh;
+ int err;
+
+ fh = ovl_encode_fh(origin, is_upper);
+ err = PTR_ERR(fh);
+ if (IS_ERR(fh)) {
+ fh = NULL;
+ goto fail;
+ }
+
+ err = ovl_verify_origin_fh(dentry, fh);
+ if (set && err == -ENODATA)
+ err = ovl_do_setxattr(dentry, OVL_XATTR_ORIGIN, fh, fh->len, 0);
+ if (err)
+ goto fail;
+
+out:
+ kfree(fh);
+ return err;
+
+fail:
+ inode = d_inode(origin);
+ pr_warn_ratelimited("overlayfs: failed to verify origin (%pd2, ino=%lu, err=%i)\n",
+ origin, inode ? inode->i_ino : 0, err);
+ goto out;
+}
+
+/*
+ * Verify that an index entry name matches the origin file handle stored in
+ * OVL_XATTR_ORIGIN and that origin file handle can be decoded to lower path.
+ * Return 0 on match, -ESTALE on mismatch or stale origin, < 0 on error.
+ */
+int ovl_verify_index(struct dentry *index, struct path *lowerstack,
+ unsigned int numlower)
+{
+ struct ovl_fh *fh = NULL;
+ size_t len;
+ struct path origin = { };
+ struct path *stack = &origin;
+ unsigned int ctr = 0;
+ int err;
+
+ if (!d_inode(index))
+ return 0;
+
+ /*
+ * Directory index entries are going to be used for looking up
+ * redirected upper dirs by lower dir fh when decoding an overlay
+ * file handle of a merge dir. Whiteout index entries are going to be
+ * used as an indication that an exported overlay file handle should
+ * be treated as stale (i.e. after unlink of the overlay inode).
+ * We don't know the verification rules for directory and whiteout
+ * index entries, because they have not been implemented yet, so return
+ * EINVAL if those entries are found to abort the mount to avoid
+ * corrupting an index that was created by a newer kernel.
+ */
+ err = -EINVAL;
+ if (d_is_dir(index) || ovl_is_whiteout(index))
+ goto fail;
+
+ if (index->d_name.len < sizeof(struct ovl_fh)*2)
+ goto fail;
+
+ err = -ENOMEM;
+ len = index->d_name.len / 2;
+ fh = kzalloc(len, GFP_KERNEL);
+ if (!fh)
+ goto fail;
+
+ err = -EINVAL;
+ if (hex2bin((u8 *)fh, index->d_name.name, len) || len != fh->len)
+ goto fail;
+
+ err = ovl_verify_origin_fh(index, fh);
+ if (err)
+ goto fail;
+
+ err = ovl_check_origin(index, lowerstack, numlower, &stack, &ctr);
+ if (!err && !ctr)
+ err = -ESTALE;
+ if (err)
+ goto fail;
+
+ /* Check if index is orphan and don't warn before cleaning it */
+ if (d_inode(index)->i_nlink == 1 &&
+ ovl_get_nlink(origin.dentry, index, 0) == 0)
+ err = -ENOENT;
+
+ dput(origin.dentry);
+out:
+ kfree(fh);
+ return err;
+
+fail:
+ pr_warn_ratelimited("overlayfs: failed to verify index (%pd2, ftype=%x, err=%i)\n",
+ index, d_inode(index)->i_mode & S_IFMT, err);
+ goto out;
+}
+
+/*
+ * Lookup in indexdir for the index entry of a lower real inode or a copy up
+ * origin inode. The index entry name is the hex representation of the lower
+ * inode file handle.
+ *
+ * If the index dentry in negative, then either no lower aliases have been
+ * copied up yet, or aliases have been copied up in older kernels and are
+ * not indexed.
+ *
+ * If the index dentry for a copy up origin inode is positive, but points
+ * to an inode different than the upper inode, then either the upper inode
+ * has been copied up and not indexed or it was indexed, but since then
+ * index dir was cleared. Either way, that index cannot be used to indentify
+ * the overlay inode.
+ */
+int ovl_get_index_name(struct dentry *origin, struct qstr *name)
+{
+ int err;
+ struct ovl_fh *fh;
+ char *n, *s;
+
+ fh = ovl_encode_fh(origin, false);
+ if (IS_ERR(fh))
+ return PTR_ERR(fh);
+
+ err = -ENOMEM;
+ n = kzalloc(fh->len * 2, GFP_KERNEL);
+ if (n) {
+ s = bin2hex(n, fh, fh->len);
+ *name = (struct qstr) QSTR_INIT(n, s - n);
+ err = 0;
+ }
+ kfree(fh);
+
+ return err;
+
+}
+
+static struct dentry *ovl_lookup_index(struct dentry *dentry,
+ struct dentry *upper,
+ struct dentry *origin)
+{
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
+ struct dentry *index;
+ struct inode *inode;
+ struct qstr name;
+ int err;
+
+ err = ovl_get_index_name(origin, &name);
+ if (err)
+ return ERR_PTR(err);
+
+ index = lookup_one_len_unlocked(name.name, ofs->indexdir, name.len);
+ if (IS_ERR(index)) {
+ err = PTR_ERR(index);
+ if (err == -ENOENT) {
+ index = NULL;
+ goto out;
+ }
+ pr_warn_ratelimited("overlayfs: failed inode index lookup (ino=%lu, key=%.*s, err=%i);\n"
+ "overlayfs: mount with '-o index=off' to disable inodes index.\n",
+ d_inode(origin)->i_ino, name.len, name.name,
+ err);
+ goto out;
+ }
+
+ inode = d_inode(index);
+ if (d_is_negative(index)) {
+ goto out_dput;
+ } else if (upper && d_inode(upper) != inode) {
+ goto out_dput;
+ } else if (ovl_dentry_weird(index) || ovl_is_whiteout(index) ||
+ ((inode->i_mode ^ d_inode(origin)->i_mode) & S_IFMT)) {
+ /*
+ * Index should always be of the same file type as origin
+ * except for the case of a whiteout index. A whiteout
+ * index should only exist if all lower aliases have been
+ * unlinked, which means that finding a lower origin on lookup
+ * whose index is a whiteout should be treated as an error.
+ */
+ pr_warn_ratelimited("overlayfs: bad index found (index=%pd2, ftype=%x, origin ftype=%x).\n",
+ index, d_inode(index)->i_mode & S_IFMT,
+ d_inode(origin)->i_mode & S_IFMT);
+ goto fail;
+ }
+
+out:
+ kfree(name.name);
+ return index;
+
+out_dput:
+ dput(index);
+ index = NULL;
+ goto out;
+
+fail:
+ dput(index);
+ index = ERR_PTR(-EIO);
+ goto out;
+}
+
+/*
+ * Returns next layer in stack starting from top.
+ * Returns -1 if this is the last layer.
+ */
+int ovl_path_next(int idx, struct dentry *dentry, struct path *path)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ BUG_ON(idx < 0);
+ if (idx == 0) {
+ ovl_path_upper(dentry, path);
+ if (path->dentry)
+ return oe->numlower ? 1 : -1;
+ idx++;
+ }
+ BUG_ON(idx > oe->numlower);
+ *path = oe->lowerstack[idx - 1];
+
+ return (idx < oe->numlower) ? idx + 1 : -1;
+}
+
+struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
+ unsigned int flags)
+{
+ struct ovl_entry *oe;
+ const struct cred *old_cred;
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
+ struct ovl_entry *poe = dentry->d_parent->d_fsdata;
+ struct ovl_entry *roe = dentry->d_sb->s_root->d_fsdata;
+ struct path *stack = NULL;
+ struct dentry *upperdir, *upperdentry = NULL;
+ struct dentry *index = NULL;
+ unsigned int ctr = 0;
+ struct inode *inode = NULL;
+ bool upperopaque = false;
+ char *upperredirect = NULL;
+ struct dentry *this;
+ unsigned int i;
+ int err;
+ struct ovl_lookup_data d = {
+ .name = dentry->d_name,
+ .is_dir = false,
+ .opaque = false,
+ .stop = false,
+ .last = !poe->numlower,
+ .redirect = NULL,
+ };
+
+ if (dentry->d_name.len > ofs->namelen)
+ return ERR_PTR(-ENAMETOOLONG);
+
+ old_cred = ovl_override_creds(dentry->d_sb);
+ upperdir = ovl_dentry_upper(dentry->d_parent);
+ if (upperdir) {
+ err = ovl_lookup_layer(upperdir, &d, &upperdentry);
+ if (err)
+ goto out;
+
+ if (upperdentry && unlikely(ovl_dentry_remote(upperdentry))) {
+ dput(upperdentry);
+ err = -EREMOTE;
+ goto out;
+ }
+ if (upperdentry && !d.is_dir) {
+ BUG_ON(!d.stop || d.redirect);
+ /*
+ * Lookup copy up origin by decoding origin file handle.
+ * We may get a disconnected dentry, which is fine,
+ * because we only need to hold the origin inode in
+ * cache and use its inode number. We may even get a
+ * connected dentry, that is not under any of the lower
+ * layers root. That is also fine for using it's inode
+ * number - it's the same as if we held a reference
+ * to a dentry in lower layer that was moved under us.
+ */
+ err = ovl_check_origin(upperdentry, roe->lowerstack,
+ roe->numlower, &stack, &ctr);
+ if (err)
+ goto out_put_upper;
+ }
+
+ if (d.redirect) {
+ err = -ENOMEM;
+ upperredirect = kstrdup(d.redirect, GFP_KERNEL);
+ if (!upperredirect)
+ goto out_put_upper;
+ if (d.redirect[0] == '/')
+ poe = roe;
+ }
+ upperopaque = d.opaque;
+ }
+
+ if (!d.stop && poe->numlower) {
+ err = -ENOMEM;
+ stack = kcalloc(ofs->numlower, sizeof(struct path),
+ GFP_KERNEL);
+ if (!stack)
+ goto out_put_upper;
+ }
+
+ for (i = 0; !d.stop && i < poe->numlower; i++) {
+ struct path lowerpath = poe->lowerstack[i];
+
+ d.last = i == poe->numlower - 1;
+ err = ovl_lookup_layer(lowerpath.dentry, &d, &this);
+ if (err)
+ goto out_put;
+
+ if (!this)
+ continue;
+
+ stack[ctr].dentry = this;
+ stack[ctr].mnt = lowerpath.mnt;
+ ctr++;
+
+ if (d.stop)
+ break;
+
+ if (d.redirect && d.redirect[0] == '/' && poe != roe) {
+ poe = roe;
+
+ /* Find the current layer on the root dentry */
+ for (i = 0; i < poe->numlower; i++)
+ if (poe->lowerstack[i].mnt == lowerpath.mnt)
+ break;
+ if (WARN_ON(i == poe->numlower))
+ break;
+ }
+ }
+
+ /* Lookup index by lower inode and verify it matches upper inode */
+ if (ctr && !d.is_dir && ovl_indexdir(dentry->d_sb)) {
+ struct dentry *origin = stack[0].dentry;
+
+ index = ovl_lookup_index(dentry, upperdentry, origin);
+ if (IS_ERR(index)) {
+ err = PTR_ERR(index);
+ index = NULL;
+ goto out_put;
+ }
+ }
+
+ oe = ovl_alloc_entry(ctr);
+ err = -ENOMEM;
+ if (!oe)
+ goto out_put;
+
+ oe->opaque = upperopaque;
+ memcpy(oe->lowerstack, stack, sizeof(struct path) * ctr);
+ dentry->d_fsdata = oe;
+
+ if (upperdentry)
+ ovl_dentry_set_upper_alias(dentry);
+ else if (index)
+ upperdentry = dget(index);
+
+ if (upperdentry || ctr) {
+ inode = ovl_get_inode(dentry, upperdentry, index);
+ err = PTR_ERR(inode);
+ if (IS_ERR(inode))
+ goto out_free_oe;
+
+ OVL_I(inode)->redirect = upperredirect;
+ if (index)
+ ovl_set_flag(OVL_INDEX, inode);
+ }
+
+ revert_creds(old_cred);
+ dput(index);
+ kfree(stack);
+ kfree(d.redirect);
+ d_add(dentry, inode);
+
+ return NULL;
+
+out_free_oe:
+ dentry->d_fsdata = NULL;
+ kfree(oe);
+out_put:
+ dput(index);
+ for (i = 0; i < ctr; i++)
+ dput(stack[i].dentry);
+ kfree(stack);
+out_put_upper:
+ dput(upperdentry);
+ kfree(upperredirect);
+out:
+ kfree(d.redirect);
+ revert_creds(old_cred);
+ return ERR_PTR(err);
+}
+
+bool ovl_lower_positive(struct dentry *dentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+ struct ovl_entry *poe = dentry->d_parent->d_fsdata;
+ const struct qstr *name = &dentry->d_name;
+ unsigned int i;
+ bool positive = false;
+ bool done = false;
+
+ /*
+ * If dentry is negative, then lower is positive iff this is a
+ * whiteout.
+ */
+ if (!dentry->d_inode)
+ return oe->opaque;
+
+ /* Negative upper -> positive lower */
+ if (!ovl_dentry_upper(dentry))
+ return true;
+
+ /* Positive upper -> have to look up lower to see whether it exists */
+ for (i = 0; !done && !positive && i < poe->numlower; i++) {
+ struct dentry *this;
+ struct dentry *lowerdir = poe->lowerstack[i].dentry;
+
+ this = lookup_one_len_unlocked(name->name, lowerdir,
+ name->len);
+ if (IS_ERR(this)) {
+ switch (PTR_ERR(this)) {
+ case -ENOENT:
+ case -ENAMETOOLONG:
+ break;
+
+ default:
+ /*
+ * Assume something is there, we just couldn't
+ * access it.
+ */
+ positive = true;
+ break;
+ }
+ } else {
+ if (this->d_inode) {
+ positive = !ovl_is_whiteout(this);
+ done = true;
+ }
+ dput(this);
+ }
+ }
+
+ return positive;
+}