Merge tag 'ovl-update-5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs

Pull overlayfs updates from Miklos Szeredi:

 - Support idmapped layers in overlayfs (Christian Brauner)

 - Add a fix to exportfs that is relevant to open_by_handle_at(2) as
   well

 - Introduce new lookup helpers that allow passing mnt_userns into
   inode_permission()

* tag 'ovl-update-5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: support idmapped layers
  ovl: handle idmappings in ovl_xattr_{g,s}et()
  ovl: handle idmappings in layer open helpers
  ovl: handle idmappings in ovl_permission()
  ovl: use ovl_copy_{real,upper}attr() wrappers
  ovl: store lower path in ovl_inode
  ovl: handle idmappings for layer lookup
  ovl: handle idmappings for layer fileattrs
  ovl: use ovl_path_getxattr() wrapper
  ovl: use ovl_lookup_upper() wrapper
  ovl: use ovl_do_notify_change() wrapper
  ovl: pass layer mnt to ovl_open_realfile()
  ovl: pass ofs to setattr operations
  ovl: handle idmappings in creation operations
  ovl: add ovl_upper_mnt_userns() wrapper
  ovl: pass ofs to creation operations
  ovl: use wrappers to all vfs_*xattr() calls
  exportfs: support idmapped mounts
  fs: add two trivial lookup helpers

fs/exportfs/expfs.c

@@ -145,7 +145,7 @@ static struct dentry *reconnect_one(struct vfsmount *mnt,
 	if (err)
 		goto out_err;
 	dprintk("%s: found name: %s\n", __func__, nbuf);
-	tmp = lookup_one_len_unlocked(nbuf, parent, strlen(nbuf));
+	tmp = lookup_one_unlocked(mnt_user_ns(mnt), nbuf, parent, strlen(nbuf));
 	if (IS_ERR(tmp)) {
 		dprintk("%s: lookup failed: %d\n", __func__, PTR_ERR(tmp));
 		err = PTR_ERR(tmp);
@@ -525,7 +525,8 @@ exportfs_decode_fh_raw(struct vfsmount *mnt, struct fid *fid, int fh_len,
 		}
 
 		inode_lock(target_dir->d_inode);
-		nresult = lookup_one_len(nbuf, target_dir, strlen(nbuf));
+		nresult = lookup_one(mnt_user_ns(mnt), nbuf,
+				     target_dir, strlen(nbuf));
 		if (!IS_ERR(nresult)) {
 			if (unlikely(nresult->d_inode != result->d_inode)) {
 				dput(nresult);

fs/namei.c

@@ -2769,7 +2769,8 @@ struct dentry *lookup_one(struct user_namespace *mnt_userns, const char *name,
 EXPORT_SYMBOL(lookup_one);
 
 /**
- * lookup_one_len_unlocked - filesystem helper to lookup single pathname component
+ * lookup_one_unlocked - filesystem helper to lookup single pathname component
+ * @mnt_userns:	idmapping of the mount the lookup is performed from
  * @name:	pathname component to lookup
  * @base:	base directory to lookup from
  * @len:	maximum length @len should be interpreted to
@@ -2780,14 +2781,15 @@ EXPORT_SYMBOL(lookup_one);
  * Unlike lookup_one_len, it should be called without the parent
  * i_mutex held, and will take the i_mutex itself if necessary.
  */
-struct dentry *lookup_one_len_unlocked(const char *name,
-				       struct dentry *base, int len)
+struct dentry *lookup_one_unlocked(struct user_namespace *mnt_userns,
+				   const char *name, struct dentry *base,
+				   int len)
 {
 	struct qstr this;
 	int err;
 	struct dentry *ret;
 
-	err = lookup_one_common(&init_user_ns, name, base, len, &this);
+	err = lookup_one_common(mnt_userns, name, base, len, &this);
 	if (err)
 		return ERR_PTR(err);
 
@@ -2796,6 +2798,59 @@ struct dentry *lookup_one_len_unlocked(const char *name,
 		ret = lookup_slow(&this, base, 0);
 	return ret;
 }
+EXPORT_SYMBOL(lookup_one_unlocked);
+
+/**
+ * lookup_one_positive_unlocked - filesystem helper to lookup single
+ *				  pathname component
+ * @mnt_userns:	idmapping of the mount the lookup is performed from
+ * @name:	pathname component to lookup
+ * @base:	base directory to lookup from
+ * @len:	maximum length @len should be interpreted to
+ *
+ * This helper will yield ERR_PTR(-ENOENT) on negatives. The helper returns
+ * known positive or ERR_PTR(). This is what most of the users want.
+ *
+ * Note that pinned negative with unlocked parent _can_ become positive at any
+ * time, so callers of lookup_one_unlocked() need to be very careful; pinned
+ * positives have >d_inode stable, so this one avoids such problems.
+ *
+ * Note that this routine is purely a helper for filesystem usage and should
+ * not be called by generic code.
+ *
+ * The helper should be called without i_mutex held.
+ */
+struct dentry *lookup_one_positive_unlocked(struct user_namespace *mnt_userns,
+					    const char *name,
+					    struct dentry *base, int len)
+{
+	struct dentry *ret = lookup_one_unlocked(mnt_userns, name, base, len);
+
+	if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) {
+		dput(ret);
+		ret = ERR_PTR(-ENOENT);
+	}
+	return ret;
+}
+EXPORT_SYMBOL(lookup_one_positive_unlocked);
+
+/**
+ * lookup_one_len_unlocked - filesystem helper to lookup single pathname component
+ * @name:	pathname component to lookup
+ * @base:	base directory to lookup from
+ * @len:	maximum length @len should be interpreted to
+ *
+ * Note that this routine is purely a helper for filesystem usage and should
+ * not be called by generic code.
+ *
+ * Unlike lookup_one_len, it should be called without the parent
+ * i_mutex held, and will take the i_mutex itself if necessary.
+ */
+struct dentry *lookup_one_len_unlocked(const char *name,
+				       struct dentry *base, int len)
+{
+	return lookup_one_unlocked(&init_user_ns, name, base, len);
+}
 EXPORT_SYMBOL(lookup_one_len_unlocked);
 
 /*
@@ -2809,12 +2864,7 @@ EXPORT_SYMBOL(lookup_one_len_unlocked);
 struct dentry *lookup_positive_unlocked(const char *name,
 				       struct dentry *base, int len)
 {
-	struct dentry *ret = lookup_one_len_unlocked(name, base, len);
-	if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) {
-		dput(ret);
-		ret = ERR_PTR(-ENOENT);
-	}
-	return ret;
+	return lookup_one_positive_unlocked(&init_user_ns, name, base, len);
 }
 EXPORT_SYMBOL(lookup_positive_unlocked);
 

fs/overlayfs/copy_up.c

@@ -44,9 +44,9 @@ static bool ovl_must_copy_xattr(const char *name)
 	       !strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN);
 }
 
-int ovl_copy_xattr(struct super_block *sb, struct dentry *old,
-		   struct dentry *new)
+int ovl_copy_xattr(struct super_block *sb, struct path *oldpath, struct dentry *new)
 {
+	struct dentry *old = oldpath->dentry;
 	ssize_t list_size, size, value_size = 0;
 	char *buf, *name, *value = NULL;
 	int error = 0;
@@ -94,9 +94,9 @@ int ovl_copy_xattr(struct super_block *sb, struct dentry *old,
 			continue; /* Discard */
 		}
 retry:
-		size = vfs_getxattr(&init_user_ns, old, name, value, value_size);
+		size = ovl_do_getxattr(oldpath, name, value, value_size);
 		if (size == -ERANGE)
-			size = vfs_getxattr(&init_user_ns, old, name, NULL, 0);
+			size = ovl_do_getxattr(oldpath, name, NULL, 0);
 
 		if (size < 0) {
 			error = size;
@@ -117,7 +117,7 @@ int ovl_copy_xattr(struct super_block *sb, struct dentry *old,
 			goto retry;
 		}
 
-		error = vfs_setxattr(&init_user_ns, new, name, value, size, 0);
+		error = ovl_do_setxattr(OVL_FS(sb), new, name, value, size, 0);
 		if (error) {
 			if (error != -EOPNOTSUPP || ovl_must_copy_xattr(name))
 				break;
@@ -292,17 +292,19 @@ static int ovl_copy_up_data(struct ovl_fs *ofs, struct path *old,
 	return error;
 }
 
-static int ovl_set_size(struct dentry *upperdentry, struct kstat *stat)
+static int ovl_set_size(struct ovl_fs *ofs,
+			struct dentry *upperdentry, struct kstat *stat)
 {
 	struct iattr attr = {
 		.ia_valid = ATTR_SIZE,
 		.ia_size = stat->size,
 	};
 
-	return notify_change(&init_user_ns, upperdentry, &attr, NULL);
+	return ovl_do_notify_change(ofs, upperdentry, &attr);
 }
 
-static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat)
+static int ovl_set_timestamps(struct ovl_fs *ofs, struct dentry *upperdentry,
+			      struct kstat *stat)
 {
 	struct iattr attr = {
 		.ia_valid =
@@ -311,10 +313,11 @@ static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat)
 		.ia_mtime = stat->mtime,
 	};
 
-	return notify_change(&init_user_ns, upperdentry, &attr, NULL);
+	return ovl_do_notify_change(ofs, upperdentry, &attr);
 }
 
-int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat)
+int ovl_set_attr(struct ovl_fs *ofs, struct dentry *upperdentry,
+		 struct kstat *stat)
 {
 	int err = 0;
 
@@ -323,7 +326,7 @@ int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat)
 			.ia_valid = ATTR_MODE,
 			.ia_mode = stat->mode,
 		};
-		err = notify_change(&init_user_ns, upperdentry, &attr, NULL);
+		err = ovl_do_notify_change(ofs, upperdentry, &attr);
 	}
 	if (!err) {
 		struct iattr attr = {
@@ -331,10 +334,10 @@ int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat)
 			.ia_uid = stat->uid,
 			.ia_gid = stat->gid,
 		};
-		err = notify_change(&init_user_ns, upperdentry, &attr, NULL);
+		err = ovl_do_notify_change(ofs, upperdentry, &attr);
 	}
 	if (!err)
-		ovl_set_timestamps(upperdentry, stat);
+		ovl_set_timestamps(ofs, upperdentry, stat);
 
 	return err;
 }
@@ -433,7 +436,7 @@ static int ovl_set_upper_fh(struct ovl_fs *ofs, struct dentry *upper,
 	if (IS_ERR(fh))
 		return PTR_ERR(fh);
 
-	err = ovl_do_setxattr(ofs, index, OVL_XATTR_UPPER, fh->buf, fh->fb.len);
+	err = ovl_setxattr(ofs, index, OVL_XATTR_UPPER, fh->buf, fh->fb.len);
 
 	kfree(fh);
 	return err;
@@ -474,7 +477,7 @@ static int ovl_create_index(struct dentry *dentry, struct dentry *origin,
 	if (err)
 		return err;
 
-	temp = ovl_create_temp(indexdir, OVL_CATTR(S_IFDIR | 0));
+	temp = ovl_create_temp(ofs, indexdir, OVL_CATTR(S_IFDIR | 0));
 	err = PTR_ERR(temp);
 	if (IS_ERR(temp))
 		goto free_name;
@@ -483,16 +486,16 @@ static int ovl_create_index(struct dentry *dentry, struct dentry *origin,
 	if (err)
 		goto out;
 
-	index = lookup_one_len(name.name, indexdir, name.len);
+	index = ovl_lookup_upper(ofs, name.name, indexdir, name.len);
 	if (IS_ERR(index)) {
 		err = PTR_ERR(index);
 	} else {
-		err = ovl_do_rename(dir, temp, dir, index, 0);
+		err = ovl_do_rename(ofs, dir, temp, dir, index, 0);
 		dput(index);
 	}
 out:
 	if (err)
-		ovl_cleanup(dir, temp);
+		ovl_cleanup(ofs, dir, temp);
 	dput(temp);
 free_name:
 	kfree(name.name);
@@ -519,6 +522,7 @@ static int ovl_link_up(struct ovl_copy_up_ctx *c)
 	int err;
 	struct dentry *upper;
 	struct dentry *upperdir = ovl_dentry_upper(c->parent);
+	struct ovl_fs *ofs = OVL_FS(c->dentry->d_sb);
 	struct inode *udir = d_inode(upperdir);
 
 	/* Mark parent "impure" because it may now contain non-pure upper */
@@ -531,16 +535,16 @@ static int ovl_link_up(struct ovl_copy_up_ctx *c)
 		return err;
 
 	inode_lock_nested(udir, I_MUTEX_PARENT);
-	upper = lookup_one_len(c->dentry->d_name.name, upperdir,
+	upper = ovl_lookup_upper(ofs, c->dentry->d_name.name, upperdir,
 				 c->dentry->d_name.len);
 	err = PTR_ERR(upper);
 	if (!IS_ERR(upper)) {
-		err = ovl_do_link(ovl_dentry_upper(c->dentry), udir, upper);
+		err = ovl_do_link(ofs, ovl_dentry_upper(c->dentry), udir, upper);
 		dput(upper);
 
 		if (!err) {
 			/* Restore timestamps on parent (best effort) */
-			ovl_set_timestamps(upperdir, &c->pstat);
+			ovl_set_timestamps(ofs, upperdir, &c->pstat);
 			ovl_dentry_set_upper_alias(c->dentry);
 		}
 	}
@@ -578,7 +582,7 @@ static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp)
 			return err;
 	}
 
-	err = ovl_copy_xattr(c->dentry->d_sb, c->lowerpath.dentry, temp);
+	err = ovl_copy_xattr(c->dentry->d_sb, &c->lowerpath, temp);
 	if (err)
 		return err;
 
@@ -614,9 +618,9 @@ static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp)
 
 	inode_lock(temp->d_inode);
 	if (S_ISREG(c->stat.mode))
-		err = ovl_set_size(temp, &c->stat);
+		err = ovl_set_size(ofs, temp, &c->stat);
 	if (!err)
-		err = ovl_set_attr(temp, &c->stat);
+		err = ovl_set_attr(ofs, temp, &c->stat);
 	inode_unlock(temp->d_inode);
 
 	return err;
@@ -656,6 +660,7 @@ static void ovl_revert_cu_creds(struct ovl_cu_creds *cc)
  */
 static int ovl_copy_up_workdir(struct ovl_copy_up_ctx *c)
 {
+	struct ovl_fs *ofs = OVL_FS(c->dentry->d_sb);
 	struct inode *inode;
 	struct inode *udir = d_inode(c->destdir), *wdir = d_inode(c->workdir);
 	struct dentry *temp, *upper;
@@ -677,7 +682,7 @@ static int ovl_copy_up_workdir(struct ovl_copy_up_ctx *c)
 	if (err)
 		goto unlock;
 
-	temp = ovl_create_temp(c->workdir, &cattr);
+	temp = ovl_create_temp(ofs, c->workdir, &cattr);
 	ovl_revert_cu_creds(&cc);
 
 	err = PTR_ERR(temp);
@@ -694,12 +699,13 @@ static int ovl_copy_up_workdir(struct ovl_copy_up_ctx *c)
 			goto cleanup;
 	}
 
-	upper = lookup_one_len(c->destname.name, c->destdir, c->destname.len);
+	upper = ovl_lookup_upper(ofs, c->destname.name, c->destdir,
+				 c->destname.len);
 	err = PTR_ERR(upper);
 	if (IS_ERR(upper))
 		goto cleanup;
 
-	err = ovl_do_rename(wdir, temp, udir, upper, 0);
+	err = ovl_do_rename(ofs, wdir, temp, udir, upper, 0);
 	dput(upper);
 	if (err)
 		goto cleanup;
@@ -716,7 +722,7 @@ static int ovl_copy_up_workdir(struct ovl_copy_up_ctx *c)
 	return err;
 
 cleanup:
-	ovl_cleanup(wdir, temp);
+	ovl_cleanup(ofs, wdir, temp);
 	dput(temp);
 	goto unlock;
 }
@@ -724,6 +730,7 @@ static int ovl_copy_up_workdir(struct ovl_copy_up_ctx *c)
 /* Copyup using O_TMPFILE which does not require cross dir locking */
 static int ovl_copy_up_tmpfile(struct ovl_copy_up_ctx *c)
 {
+	struct ovl_fs *ofs = OVL_FS(c->dentry->d_sb);
 	struct inode *udir = d_inode(c->destdir);
 	struct dentry *temp, *upper;
 	struct ovl_cu_creds cc;
@@ -733,7 +740,7 @@ static int ovl_copy_up_tmpfile(struct ovl_copy_up_ctx *c)
 	if (err)
 		return err;
 
-	temp = ovl_do_tmpfile(c->workdir, c->stat.mode);
+	temp = ovl_do_tmpfile(ofs, c->workdir, c->stat.mode);
 	ovl_revert_cu_creds(&cc);
 
 	if (IS_ERR(temp))
@@ -745,10 +752,11 @@ static int ovl_copy_up_tmpfile(struct ovl_copy_up_ctx *c)
 
 	inode_lock_nested(udir, I_MUTEX_PARENT);
 
-	upper = lookup_one_len(c->destname.name, c->destdir, c->destname.len);
+	upper = ovl_lookup_upper(ofs, c->destname.name, c->destdir,
+				 c->destname.len);
 	err = PTR_ERR(upper);
 	if (!IS_ERR(upper)) {
-		err = ovl_do_link(temp, udir, upper);
+		err = ovl_do_link(ofs, temp, udir, upper);
 		dput(upper);
 	}
 	inode_unlock(udir);
@@ -836,7 +844,7 @@ static int ovl_do_copy_up(struct ovl_copy_up_ctx *c)
 
 		/* Restore timestamps on parent (best effort) */
 		inode_lock(udir);
-		ovl_set_timestamps(c->destdir, &c->pstat);
+		ovl_set_timestamps(ofs, c->destdir, &c->pstat);
 		inode_unlock(udir);
 
 		ovl_dentry_set_upper_alias(c->dentry);
@@ -865,12 +873,12 @@ static bool ovl_need_meta_copy_up(struct dentry *dentry, umode_t mode,
 	return true;
 }
 
-static ssize_t ovl_getxattr(struct dentry *dentry, char *name, char **value)
+static ssize_t ovl_getxattr_value(struct path *path, char *name, char **value)
 {
 	ssize_t res;
 	char *buf;
 
-	res = vfs_getxattr(&init_user_ns, dentry, name, NULL, 0);
+	res = ovl_do_getxattr(path, name, NULL, 0);
 	if (res == -ENODATA || res == -EOPNOTSUPP)
 		res = 0;
 
@@ -879,7 +887,7 @@ static ssize_t ovl_getxattr(struct dentry *dentry, char *name, char **value)
 		if (!buf)
 			return -ENOMEM;
 
-		res = vfs_getxattr(&init_user_ns, dentry, name, buf, res);
+		res = ovl_do_getxattr(path, name, buf, res);
 		if (res < 0)
 			kfree(buf);
 		else
@@ -906,7 +914,7 @@ static int ovl_copy_up_meta_inode_data(struct ovl_copy_up_ctx *c)
 		return -EIO;
 
 	if (c->stat.size) {
-		err = cap_size = ovl_getxattr(upperpath.dentry, XATTR_NAME_CAPS,
+		err = cap_size = ovl_getxattr_value(&upperpath, XATTR_NAME_CAPS,
 						    &capability);
 		if (cap_size < 0)
 			goto out;
@@ -921,14 +929,14 @@ static int ovl_copy_up_meta_inode_data(struct ovl_copy_up_ctx *c)
 	 * don't want that to happen for normal copy-up operation.
 	 */
 	if (capability) {
-		err = vfs_setxattr(&init_user_ns, upperpath.dentry,
-				   XATTR_NAME_CAPS, capability, cap_size, 0);
+		err = ovl_do_setxattr(ofs, upperpath.dentry, XATTR_NAME_CAPS,
+				      capability, cap_size, 0);
 		if (err)
 			goto out_free;
 	}
 
 
-	err = ovl_do_removexattr(ofs, upperpath.dentry, OVL_XATTR_METACOPY);
+	err = ovl_removexattr(ofs, upperpath.dentry, OVL_XATTR_METACOPY);
 	if (err)
 		goto out_free;
 

fs/overlayfs/export.c

@@ -391,6 +391,11 @@ static struct dentry *ovl_lookup_real_one(struct dentry *connected,
 	 * pointer because we hold no lock on the real dentry.
 	 */
 	take_dentry_name_snapshot(&name, real);
+	/*
+	 * No mnt_userns handling here: it's an internal lookup.  Could skip
+	 * permission checking altogether, but for now just use non-mnt_userns
+	 * transformed ids.
+	 */
 	this = lookup_one_len(name.name.name, connected, name.name.len);
 	release_dentry_name_snapshot(&name);
 	err = PTR_ERR(this);

fs/overlayfs/file.c

@@ -38,9 +38,11 @@ static char ovl_whatisit(struct inode *inode, struct inode *realinode)
 #define OVL_OPEN_FLAGS (O_NOATIME | FMODE_NONOTIFY)
 
 static struct file *ovl_open_realfile(const struct file *file,
-				      struct inode *realinode)
+				      struct path *realpath)
 {
+	struct inode *realinode = d_inode(realpath->dentry);
 	struct inode *inode = file_inode(file);
+	struct user_namespace *real_mnt_userns;
 	struct file *realfile;
 	const struct cred *old_cred;
 	int flags = file->f_flags | OVL_OPEN_FLAGS;
@@ -51,11 +53,12 @@ static struct file *ovl_open_realfile(const struct file *file,
 		acc_mode |= MAY_APPEND;
 
 	old_cred = ovl_override_creds(inode->i_sb);
-	err = inode_permission(&init_user_ns, realinode, MAY_OPEN | acc_mode);
+	real_mnt_userns = mnt_user_ns(realpath->mnt);
+	err = inode_permission(real_mnt_userns, realinode, MAY_OPEN | acc_mode);
 	if (err) {
 		realfile = ERR_PTR(err);
 	} else {
-		if (!inode_owner_or_capable(&init_user_ns, realinode))
+		if (!inode_owner_or_capable(real_mnt_userns, realinode))
 			flags &= ~O_NOATIME;
 
 		realfile = open_with_fake_path(&file->f_path, flags, realinode,
@@ -101,21 +104,21 @@ static int ovl_change_flags(struct file *file, unsigned int flags)
 static int ovl_real_fdget_meta(const struct file *file, struct fd *real,
 			       bool allow_meta)
 {
-	struct inode *inode = file_inode(file);
-	struct inode *realinode;
+	struct dentry *dentry = file_dentry(file);
+	struct path realpath;
 
 	real->flags = 0;
 	real->file = file->private_data;
 
 	if (allow_meta)
-		realinode = ovl_inode_real(inode);
+		ovl_path_real(dentry, &realpath);
 	else
-		realinode = ovl_inode_realdata(inode);
+		ovl_path_realdata(dentry, &realpath);
 
 	/* Has it been copied up since we'd opened it? */
-	if (unlikely(file_inode(real->file) != realinode)) {
+	if (unlikely(file_inode(real->file) != d_inode(realpath.dentry))) {
 		real->flags = FDPUT_FPUT;
-		real->file = ovl_open_realfile(file, realinode);
+		real->file = ovl_open_realfile(file, &realpath);
 
 		return PTR_ERR_OR_ZERO(real->file);
 	}
@@ -141,17 +144,20 @@ static int ovl_real_fdget(const struct file *file, struct fd *real)
 
 static int ovl_open(struct inode *inode, struct file *file)
 {
+	struct dentry *dentry = file_dentry(file);
 	struct file *realfile;
+	struct path realpath;
 	int err;
 
-	err = ovl_maybe_copy_up(file_dentry(file), file->f_flags);
+	err = ovl_maybe_copy_up(dentry, file->f_flags);
 	if (err)
 		return err;
 
 	/* No longer need these flags, so don't pass them on to underlying fs */
 	file->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
 
-	realfile = ovl_open_realfile(file, ovl_inode_realdata(inode));
+	ovl_path_realdata(dentry, &realpath);
+	realfile = ovl_open_realfile(file, &realpath);
 	if (IS_ERR(realfile))
 		return PTR_ERR(realfile);
 
@@ -270,7 +276,7 @@ static void ovl_aio_cleanup_handler(struct ovl_aio_req *aio_req)
 		__sb_writers_acquired(file_inode(iocb->ki_filp)->i_sb,
 				      SB_FREEZE_WRITE);
 		file_end_write(iocb->ki_filp);
-		ovl_copyattr(ovl_inode_real(inode), inode);
+		ovl_copyattr(inode);
 	}
 
 	orig_iocb->ki_pos = iocb->ki_pos;
@@ -352,7 +358,7 @@ static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter)
 
 	inode_lock(inode);
 	/* Update mode */
-	ovl_copyattr(ovl_inode_real(inode), inode);
+	ovl_copyattr(inode);
 	ret = file_remove_privs(file);
 	if (ret)
 		goto out_unlock;
@@ -376,7 +382,7 @@ static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter)
 				     ovl_iocb_to_rwf(ifl));
 		file_end_write(real.file);
 		/* Update size */
-		ovl_copyattr(ovl_inode_real(inode), inode);
+		ovl_copyattr(inode);
 	} else {
 		struct ovl_aio_req *aio_req;
 
@@ -426,12 +432,11 @@ static ssize_t ovl_splice_write(struct pipe_inode_info *pipe, struct file *out,
 	struct fd real;
 	const struct cred *old_cred;
 	struct inode *inode = file_inode(out);
-	struct inode *realinode = ovl_inode_real(inode);
 	ssize_t ret;
 
 	inode_lock(inode);
 	/* Update mode */
-	ovl_copyattr(realinode, inode);
+	ovl_copyattr(inode);
 	ret = file_remove_privs(out);
 	if (ret)
 		goto out_unlock;
@@ -447,7 +452,7 @@ static ssize_t ovl_splice_write(struct pipe_inode_info *pipe, struct file *out,
 
 	file_end_write(real.file);
 	/* Update size */
-	ovl_copyattr(realinode, inode);
+	ovl_copyattr(inode);
 	revert_creds(old_cred);
 	fdput(real);
 
@@ -521,7 +526,7 @@ static long ovl_fallocate(struct file *file, int mode, loff_t offset, loff_t len
 	revert_creds(old_cred);
 
 	/* Update size */
-	ovl_copyattr(ovl_inode_real(inode), inode);
+	ovl_copyattr(inode);
 
 	fdput(real);
 
@@ -593,7 +598,7 @@ static loff_t ovl_copyfile(struct file *file_in, loff_t pos_in,
 	revert_creds(old_cred);
 
 	/* Update size */
-	ovl_copyattr(ovl_inode_real(inode_out), inode_out);
+	ovl_copyattr(inode_out);
 
 	fdput(real_in);
 	fdput(real_out);

fs/overlayfs/inode.c

@@ -21,6 +21,7 @@ int ovl_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
 		struct iattr *attr)
 {
 	int err;
+	struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
 	bool full_copy_up = false;
 	struct dentry *upperdentry;
 	const struct cred *old_cred;
@@ -77,10 +78,10 @@ int ovl_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
 
 		inode_lock(upperdentry->d_inode);
 		old_cred = ovl_override_creds(dentry->d_sb);
-		err = notify_change(&init_user_ns, upperdentry, attr, NULL);
+		err = ovl_do_notify_change(ofs, upperdentry, attr);
 		revert_creds(old_cred);
 		if (!err)
-			ovl_copyattr(upperdentry->d_inode, dentry->d_inode);
+			ovl_copyattr(dentry->d_inode);
 		inode_unlock(upperdentry->d_inode);
 
 		if (winode)
@@ -279,12 +280,14 @@ int ovl_permission(struct user_namespace *mnt_userns,
 		   struct inode *inode, int mask)
 {
 	struct inode *upperinode = ovl_inode_upper(inode);
-	struct inode *realinode = upperinode ?: ovl_inode_lower(inode);
+	struct inode *realinode;
+	struct path realpath;
 	const struct cred *old_cred;
 	int err;
 
 	/* Careful in RCU walk mode */
-	if (!realinode) {
+	ovl_i_path_real(inode, &realpath);
+	if (!realpath.dentry) {
 		WARN_ON(!(mask & MAY_NOT_BLOCK));
 		return -ECHILD;
 	}
@@ -297,6 +300,7 @@ int ovl_permission(struct user_namespace *mnt_userns,
 	if (err)
 		return err;
 
+	realinode = d_inode(realpath.dentry);
 	old_cred = ovl_override_creds(inode->i_sb);
 	if (!upperinode &&
 	    !special_file(realinode->i_mode) && mask & MAY_WRITE) {
@@ -304,7 +308,7 @@ int ovl_permission(struct user_namespace *mnt_userns,
 		/* Make sure mounter can read file for copy up later */
 		mask |= MAY_READ;
 	}
-	err = inode_permission(&init_user_ns, realinode, mask);
+	err = inode_permission(mnt_user_ns(realpath.mnt), realinode, mask);
 	revert_creds(old_cred);
 
 	return err;
@@ -342,8 +346,10 @@ int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,
 		  const void *value, size_t size, int flags)
 {
 	int err;
+	struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
 	struct dentry *upperdentry = ovl_i_dentry_upper(inode);
 	struct dentry *realdentry = upperdentry ?: ovl_dentry_lower(dentry);
+	struct path realpath;
 	const struct cred *old_cred;
 
 	err = ovl_want_write(dentry);
@@ -351,8 +357,9 @@ int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,
 		goto out;
 
 	if (!value && !upperdentry) {
+		ovl_path_lower(dentry, &realpath);
 		old_cred = ovl_override_creds(dentry->d_sb);
-		err = vfs_getxattr(&init_user_ns, realdentry, name, NULL, 0);
+		err = vfs_getxattr(mnt_user_ns(realpath.mnt), realdentry, name, NULL, 0);
 		revert_creds(old_cred);
 		if (err < 0)
 			goto out_drop_write;
@@ -367,17 +374,17 @@ int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,
 	}
 
 	old_cred = ovl_override_creds(dentry->d_sb);
-	if (value)
-		err = vfs_setxattr(&init_user_ns, realdentry, name, value, size,
+	if (value) {
+		err = ovl_do_setxattr(ofs, realdentry, name, value, size,
 				      flags);
-	else {
+	} else {
 		WARN_ON(flags != XATTR_REPLACE);
-		err = vfs_removexattr(&init_user_ns, realdentry, name);
+		err = ovl_do_removexattr(ofs, realdentry, name);
 	}
 	revert_creds(old_cred);
 
 	/* copy c/mtime */
-	ovl_copyattr(d_inode(realdentry), inode);
+	ovl_copyattr(inode);
 
 out_drop_write:
 	ovl_drop_write(dentry);
@@ -390,11 +397,11 @@ int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name,
 {
 	ssize_t res;
 	const struct cred *old_cred;
-	struct dentry *realdentry =
-		ovl_i_dentry_upper(inode) ?: ovl_dentry_lower(dentry);
+	struct path realpath;
 
+	ovl_i_path_real(inode, &realpath);
 	old_cred = ovl_override_creds(dentry->d_sb);
-	res = vfs_getxattr(&init_user_ns, realdentry, name, value, size);
+	res = vfs_getxattr(mnt_user_ns(realpath.mnt), realpath.dentry, name, value, size);
 	revert_creds(old_cred);
 	return res;
 }
@@ -535,7 +542,7 @@ int ovl_real_fileattr_set(struct path *realpath, struct fileattr *fa)
 	if (err)
 		return err;
 
-	return vfs_fileattr_set(&init_user_ns, realpath->dentry, fa);
+	return vfs_fileattr_set(mnt_user_ns(realpath->mnt), realpath->dentry, fa);
 }
 
 int ovl_fileattr_set(struct user_namespace *mnt_userns,
@@ -579,7 +586,7 @@ int ovl_fileattr_set(struct user_namespace *mnt_userns,
 		inode_set_flags(inode, flags, OVL_COPY_I_FLAGS_MASK);
 
 		/* Update ctime */
-		ovl_copyattr(ovl_inode_real(inode), inode);
+		ovl_copyattr(inode);
 	}
 	ovl_drop_write(dentry);
 out:
@@ -777,16 +784,19 @@ void ovl_inode_init(struct inode *inode, struct ovl_inode_params *oip,
 		    unsigned long ino, int fsid)
 {
 	struct inode *realinode;
+	struct ovl_inode *oi = OVL_I(inode);
 
 	if (oip->upperdentry)
-		OVL_I(inode)->__upperdentry = oip->upperdentry;
-	if (oip->lowerpath && oip->lowerpath->dentry)
-		OVL_I(inode)->lower = igrab(d_inode(oip->lowerpath->dentry));
+		oi->__upperdentry = oip->upperdentry;
+	if (oip->lowerpath && oip->lowerpath->dentry) {
+		oi->lowerpath.dentry = dget(oip->lowerpath->dentry);
+		oi->lowerpath.layer = oip->lowerpath->layer;
+	}
 	if (oip->lowerdata)
-		OVL_I(inode)->lowerdata = igrab(d_inode(oip->lowerdata));
+		oi->lowerdata = igrab(d_inode(oip->lowerdata));
 
 	realinode = ovl_inode_real(inode);
-	ovl_copyattr(realinode, inode);
+	ovl_copyattr(inode);
 	ovl_copyflags(realinode, inode);
 	ovl_map_ino(inode, ino, fsid);
 }
@@ -871,7 +881,7 @@ static int ovl_set_nlink_common(struct dentry *dentry,
 	if (WARN_ON(len >= sizeof(buf)))
 		return -EIO;
 
-	return ovl_do_setxattr(OVL_FS(inode->i_sb), ovl_dentry_upper(dentry),
+	return ovl_setxattr(OVL_FS(inode->i_sb), ovl_dentry_upper(dentry),
 			    OVL_XATTR_NLINK, buf, len);
 }
 
@@ -897,7 +907,7 @@ unsigned int ovl_get_nlink(struct ovl_fs *ofs, struct dentry *lowerdentry,
 	if (!lowerdentry || !upperdentry || d_inode(lowerdentry)->i_nlink == 1)
 		return fallback;
 
-	err = ovl_do_getxattr(ofs, upperdentry, OVL_XATTR_NLINK,
+	err = ovl_getxattr_upper(ofs, upperdentry, OVL_XATTR_NLINK,
 				 &buf, sizeof(buf) - 1);
 	if (err < 0)
 		goto fail;
@@ -1102,6 +1112,10 @@ struct inode *ovl_get_inode(struct super_block *sb,
 	struct inode *realinode = upperdentry ? d_inode(upperdentry) : NULL;
 	struct inode *inode;
 	struct dentry *lowerdentry = lowerpath ? lowerpath->dentry : NULL;
+	struct path realpath = {
+		.dentry = upperdentry ?: lowerdentry,
+		.mnt = upperdentry ? ovl_upper_mnt(ofs) : lowerpath->layer->mnt,
+	};
 	bool bylower = ovl_hash_bylower(sb, upperdentry, lowerdentry,
 					oip->index);
 	int fsid = bylower ? lowerpath->layer->fsid : 0;
@@ -1175,7 +1189,7 @@ struct inode *ovl_get_inode(struct super_block *sb,
 	/* Check for non-merge dir that may have whiteouts */
 	if (is_dir) {
 		if (((upperdentry && lowerdentry) || oip->numlower > 1) ||
-		    ovl_check_origin_xattr(ofs, upperdentry ?: lowerdentry)) {
+		    ovl_path_check_origin_xattr(ofs, &realpath)) {
 			ovl_set_flag(OVL_WHITEOUTS, inode);
 		}
 	}

fs/overlayfs/namei.c

@@ -16,6 +16,7 @@
 
 struct ovl_lookup_data {
 	struct super_block *sb;
+	struct vfsmount *mnt;
 	struct qstr name;
 	bool is_dir;
 	bool opaque;
@@ -25,14 +26,14 @@ struct ovl_lookup_data {
 	bool metacopy;
 };
 
-static int ovl_check_redirect(struct dentry *dentry, struct ovl_lookup_data *d,
+static int ovl_check_redirect(struct path *path, struct ovl_lookup_data *d,
 			      size_t prelen, const char *post)
 {
 	int res;
 	char *buf;
 	struct ovl_fs *ofs = OVL_FS(d->sb);
 
-	buf = ovl_get_redirect_xattr(ofs, dentry, prelen + strlen(post));
+	buf = ovl_get_redirect_xattr(ofs, path, prelen + strlen(post));
 	if (IS_ERR_OR_NULL(buf))
 		return PTR_ERR(buf);
 
@@ -105,13 +106,13 @@ int ovl_check_fb_len(struct ovl_fb *fb, int fb_len)
 	return 0;
 }
 
-static struct ovl_fh *ovl_get_fh(struct ovl_fs *ofs, struct dentry *dentry,
+static struct ovl_fh *ovl_get_fh(struct ovl_fs *ofs, struct dentry *upperdentry,
 				 enum ovl_xattr ox)
 {
 	int res, err;
 	struct ovl_fh *fh = NULL;
 
-	res = ovl_do_getxattr(ofs, dentry, ox, NULL, 0);
+	res = ovl_getxattr_upper(ofs, upperdentry, ox, NULL, 0);
 	if (res < 0) {
 		if (res == -ENODATA || res == -EOPNOTSUPP)
 			return NULL;
@@ -125,7 +126,7 @@ static struct ovl_fh *ovl_get_fh(struct ovl_fs *ofs, struct dentry *dentry,
 	if (!fh)
 		return ERR_PTR(-ENOMEM);
 
-	res = ovl_do_getxattr(ofs, dentry, ox, fh->buf, res);
+	res = ovl_getxattr_upper(ofs, upperdentry, ox, fh->buf, res);
 	if (res < 0)
 		goto fail;
 
@@ -193,16 +194,17 @@ struct dentry *ovl_decode_real_fh(struct ovl_fs *ofs, struct ovl_fh *fh,
 	return real;
 }
 
-static bool ovl_is_opaquedir(struct super_block *sb, struct dentry *dentry)
+static bool ovl_is_opaquedir(struct ovl_fs *ofs, struct path *path)
 {
-	return ovl_check_dir_xattr(sb, dentry, OVL_XATTR_OPAQUE);
+	return ovl_path_check_dir_xattr(ofs, path, OVL_XATTR_OPAQUE);
 }
 
-static struct dentry *ovl_lookup_positive_unlocked(const char *name,
+static struct dentry *ovl_lookup_positive_unlocked(struct ovl_lookup_data *d,
+						   const char *name,
 						   struct dentry *base, int len,
 						   bool drop_negative)
 {
-	struct dentry *ret = lookup_one_len_unlocked(name, base, len);
+	struct dentry *ret = lookup_one_unlocked(mnt_user_ns(d->mnt), name, base, len);
 
 	if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) {
 		if (drop_negative && ret->d_lockref.count == 1) {
@@ -224,10 +226,11 @@ static int ovl_lookup_single(struct dentry *base, struct ovl_lookup_data *d,
 			     struct dentry **ret, bool drop_negative)
 {
 	struct dentry *this;
+	struct path path;
 	int err;
 	bool last_element = !post[0];
 
-	this = ovl_lookup_positive_unlocked(name, base, namelen, drop_negative);
+	this = ovl_lookup_positive_unlocked(d, name, base, namelen, drop_negative);
 	if (IS_ERR(this)) {
 		err = PTR_ERR(this);
 		this = NULL;
@@ -253,12 +256,15 @@ static int ovl_lookup_single(struct dentry *base, struct ovl_lookup_data *d,
 		d->stop = true;
 		goto put_and_out;
 	}
+
+	path.dentry = this;
+	path.mnt = d->mnt;
 	if (!d_can_lookup(this)) {
 		if (d->is_dir || !last_element) {
 			d->stop = true;
 			goto put_and_out;
 		}
-		err = ovl_check_metacopy_xattr(OVL_FS(d->sb), this);
+		err = ovl_check_metacopy_xattr(OVL_FS(d->sb), &path);
 		if (err < 0)
 			goto out_err;
 
@@ -278,14 +284,14 @@ static int ovl_lookup_single(struct dentry *base, struct ovl_lookup_data *d,
 		if (d->last)
 			goto out;
 
-		if (ovl_is_opaquedir(d->sb, this)) {
+		if (ovl_is_opaquedir(OVL_FS(d->sb), &path)) {
 			d->stop = true;
 			if (last_element)
 				d->opaque = true;
 			goto out;
 		}
 	}
-	err = ovl_check_redirect(this, d, prelen, post);
+	err = ovl_check_redirect(&path, d, prelen, post);
 	if (err)
 		goto out_err;
 out:
@@ -464,7 +470,7 @@ int ovl_verify_set_fh(struct ovl_fs *ofs, struct dentry *dentry,
 
 	err = ovl_verify_fh(ofs, dentry, ox, fh);
 	if (set && err == -ENODATA)
-		err = ovl_do_setxattr(ofs, dentry, ox, fh->buf, fh->fb.len);
+		err = ovl_setxattr(ofs, dentry, ox, fh->buf, fh->fb.len);
 	if (err)
 		goto fail;
 
@@ -704,7 +710,8 @@ struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper,
 	if (err)
 		return ERR_PTR(err);
 
-	index = lookup_positive_unlocked(name.name, ofs->indexdir, name.len);
+	index = lookup_one_positive_unlocked(ovl_upper_mnt_userns(ofs), name.name,
+					     ofs->indexdir, name.len);
 	if (IS_ERR(index)) {
 		err = PTR_ERR(index);
 		if (err == -ENOENT) {
@@ -856,6 +863,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 	old_cred = ovl_override_creds(dentry->d_sb);
 	upperdir = ovl_dentry_upper(dentry->d_parent);
 	if (upperdir) {
+		d.mnt = ovl_upper_mnt(ofs);
 		err = ovl_lookup_layer(upperdir, &d, &upperdentry, true);
 		if (err)
 			goto out;
@@ -911,6 +919,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 		else
 			d.last = lower.layer->idx == roe->numlower;
 
+		d.mnt = lower.layer->mnt;
 		err = ovl_lookup_layer(lower.dentry, &d, &this, false);
 		if (err)
 			goto out_put;
@@ -1071,14 +1080,18 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 	if (upperdentry)
 		ovl_dentry_set_upper_alias(dentry);
 	else if (index) {
-		upperdentry = dget(index);
-		upperredirect = ovl_get_redirect_xattr(ofs, upperdentry, 0);
+		struct path upperpath = {
+			.dentry = upperdentry = dget(index),
+			.mnt = ovl_upper_mnt(ofs),
+		};
+
+		upperredirect = ovl_get_redirect_xattr(ofs, &upperpath, 0);
 		if (IS_ERR(upperredirect)) {
 			err = PTR_ERR(upperredirect);
 			upperredirect = NULL;
 			goto out_free_oe;
 		}
-		err = ovl_check_metacopy_xattr(ofs, upperdentry);
+		err = ovl_check_metacopy_xattr(ofs, &upperpath);
 		if (err < 0)
 			goto out_free_oe;
 		uppermetacopy = err;
@@ -1163,8 +1176,8 @@ bool ovl_lower_positive(struct dentry *dentry)
 		struct dentry *this;
 		struct dentry *lowerdir = poe->lowerstack[i].dentry;
 
-		this = lookup_positive_unlocked(name->name, lowerdir,
-					       name->len);
+		this = lookup_one_positive_unlocked(mnt_user_ns(poe->lowerstack[i].layer->mnt),
+						   name->name, lowerdir, name->len);
 		if (IS_ERR(this)) {
 			switch (PTR_ERR(this)) {
 			case -ENOENT:

fs/overlayfs/ovl_entry.h

@@ -90,6 +90,11 @@ static inline struct vfsmount *ovl_upper_mnt(struct ovl_fs *ofs)
 	return ofs->layers[0].mnt;
 }
 
+static inline struct user_namespace *ovl_upper_mnt_userns(struct ovl_fs *ofs)
+{
+	return mnt_user_ns(ovl_upper_mnt(ofs));
+}
+
 static inline struct ovl_fs *OVL_FS(struct super_block *sb)
 {
 	return (struct ovl_fs *)sb->s_fs_info;
@@ -129,7 +134,7 @@ struct ovl_inode {
 	unsigned long flags;
 	struct inode vfs_inode;
 	struct dentry *__upperdentry;
-	struct inode *lower;
+	struct ovl_path lowerpath;
 
 	/* synchronize copy up and more */
 	struct mutex lock;

fs/overlayfs/readdir.c

@@ -264,11 +264,11 @@ static int ovl_fill_merge(struct dir_context *ctx, const char *name,
 		return ovl_fill_lowest(rdd, name, namelen, offset, ino, d_type);
 }
 
-static int ovl_check_whiteouts(struct dentry *dir, struct ovl_readdir_data *rdd)
+static int ovl_check_whiteouts(struct path *path, struct ovl_readdir_data *rdd)
 {
 	int err;
 	struct ovl_cache_entry *p;
-	struct dentry *dentry;
+	struct dentry *dentry, *dir = path->dentry;
 	const struct cred *old_cred;
 
 	old_cred = ovl_override_creds(rdd->dentry->d_sb);
@@ -278,7 +278,7 @@ static int ovl_check_whiteouts(struct dentry *dir, struct ovl_readdir_data *rdd)
 		while (rdd->first_maybe_whiteout) {
 			p = rdd->first_maybe_whiteout;
 			rdd->first_maybe_whiteout = p->next_maybe_whiteout;
-			dentry = lookup_one_len(p->name, dir, p->len);
+			dentry = lookup_one(mnt_user_ns(path->mnt), p->name, dir, p->len);
 			if (!IS_ERR(dentry)) {
 				p->is_whiteout = ovl_is_whiteout(dentry);
 				dput(dentry);
@@ -312,7 +312,7 @@ static inline int ovl_dir_read(struct path *realpath,
 	} while (!err && rdd->count);
 
 	if (!err && rdd->first_maybe_whiteout && rdd->dentry)
-		err = ovl_check_whiteouts(realpath->dentry, rdd);
+		err = ovl_check_whiteouts(realpath, rdd);
 
 	fput(realfile);
 
@@ -479,7 +479,7 @@ static int ovl_cache_update_ino(struct path *path, struct ovl_cache_entry *p)
 			goto get;
 		}
 	}
-	this = lookup_one_len(p->name, dir, p->len);
+	this = lookup_one(mnt_user_ns(path->mnt), p->name, dir, p->len);
 	if (IS_ERR_OR_NULL(this) || !this->d_inode) {
 		/* Mark a stale entry */
 		p->is_whiteout = true;
@@ -623,7 +623,7 @@ static struct ovl_dir_cache *ovl_cache_get_impure(struct path *path)
 		 * Removing the "impure" xattr is best effort.
 		 */
 		if (!ovl_want_write(dentry)) {
-			ovl_do_removexattr(ofs, ovl_dentry_upper(dentry),
+			ovl_removexattr(ofs, ovl_dentry_upper(dentry),
 					OVL_XATTR_IMPURE);
 			ovl_drop_write(dentry);
 		}
@@ -1001,7 +1001,8 @@ int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list)
 	return err;
 }
 
-void ovl_cleanup_whiteouts(struct dentry *upper, struct list_head *list)
+void ovl_cleanup_whiteouts(struct ovl_fs *ofs, struct dentry *upper,
+			   struct list_head *list)
 {
 	struct ovl_cache_entry *p;
 
@@ -1012,7 +1013,7 @@ void ovl_cleanup_whiteouts(struct dentry *upper, struct list_head *list)
 		if (WARN_ON(!p->is_whiteout || !p->is_upper))
 			continue;
 
-		dentry = lookup_one_len(p->name, upper, p->len);
+		dentry = ovl_lookup_upper(ofs, p->name, upper, p->len);
 		if (IS_ERR(dentry)) {
 			pr_err("lookup '%s/%.*s' failed (%i)\n",
 			       upper->d_name.name, p->len, p->name,
@@ -1020,7 +1021,7 @@ void ovl_cleanup_whiteouts(struct dentry *upper, struct list_head *list)
 			continue;
 		}
 		if (dentry->d_inode)
-			ovl_cleanup(upper->d_inode, dentry);
+			ovl_cleanup(ofs, upper->d_inode, dentry);
 		dput(dentry);
 	}
 	inode_unlock(upper->d_inode);
@@ -1064,7 +1065,8 @@ int ovl_check_d_type_supported(struct path *realpath)
 
 #define OVL_INCOMPATDIR_NAME "incompat"
 
-static int ovl_workdir_cleanup_recurse(struct path *path, int level)
+static int ovl_workdir_cleanup_recurse(struct ovl_fs *ofs, struct path *path,
+				       int level)
 {
 	int err;
 	struct inode *dir = path->dentry->d_inode;
@@ -1111,11 +1113,11 @@ static int ovl_workdir_cleanup_recurse(struct path *path, int level)
 			err = -EINVAL;
 			break;
 		}
-		dentry = lookup_one_len(p->name, path->dentry, p->len);
+		dentry = ovl_lookup_upper(ofs, p->name, path->dentry, p->len);
 		if (IS_ERR(dentry))
 			continue;
 		if (dentry->d_inode)
-			err = ovl_workdir_cleanup(dir, path->mnt, dentry, level);
+			err = ovl_workdir_cleanup(ofs, dir, path->mnt, dentry, level);
 		dput(dentry);
 		if (err)
 			break;
@@ -1126,24 +1128,24 @@ static int ovl_workdir_cleanup_recurse(struct path *path, int level)
 	return err;
 }
 
-int ovl_workdir_cleanup(struct inode *dir, struct vfsmount *mnt,
-			 struct dentry *dentry, int level)
+int ovl_workdir_cleanup(struct ovl_fs *ofs, struct inode *dir,
+			struct vfsmount *mnt, struct dentry *dentry, int level)
 {
 	int err;
 
 	if (!d_is_dir(dentry) || level > 1) {
-		return ovl_cleanup(dir, dentry);
+		return ovl_cleanup(ofs, dir, dentry);
 	}
 
-	err = ovl_do_rmdir(dir, dentry);
+	err = ovl_do_rmdir(ofs, dir, dentry);
 	if (err) {
 		struct path path = { .mnt = mnt, .dentry = dentry };
 
 		inode_unlock(dir);
-		err = ovl_workdir_cleanup_recurse(&path, level + 1);
+		err = ovl_workdir_cleanup_recurse(ofs, &path, level + 1);
 		inode_lock_nested(dir, I_MUTEX_PARENT);
 		if (!err)
-			err = ovl_cleanup(dir, dentry);
+			err = ovl_cleanup(ofs, dir, dentry);
 	}
 
 	return err;
@@ -1179,7 +1181,7 @@ int ovl_indexdir_cleanup(struct ovl_fs *ofs)
 			if (p->len == 2 && p->name[1] == '.')
 				continue;
 		}
-		index = lookup_one_len(p->name, indexdir, p->len);
+		index = ovl_lookup_upper(ofs, p->name, indexdir, p->len);
 		if (IS_ERR(index)) {
 			err = PTR_ERR(index);
 			index = NULL;
@@ -1187,7 +1189,7 @@ int ovl_indexdir_cleanup(struct ovl_fs *ofs)
 		}
 		/* Cleanup leftover from index create/cleanup attempt */
 		if (index->d_name.name[0] == '#') {
-			err = ovl_workdir_cleanup(dir, path.mnt, index, 1);
+			err = ovl_workdir_cleanup(ofs, dir, path.mnt, index, 1);
 			if (err)
 				break;
 			goto next;
@@ -1197,7 +1199,7 @@ int ovl_indexdir_cleanup(struct ovl_fs *ofs)
 			goto next;
 		} else if (err == -ESTALE) {
 			/* Cleanup stale index entries */
-			err = ovl_cleanup(dir, index);
+			err = ovl_cleanup(ofs, dir, index);
 		} else if (err != -ENOENT) {
 			/*
 			 * Abort mount to avoid corrupting the index if
@@ -1213,7 +1215,7 @@ int ovl_indexdir_cleanup(struct ovl_fs *ofs)
 			err = ovl_cleanup_and_whiteout(ofs, dir, index);
 		} else {
 			/* Cleanup orphan index entries */
-			err = ovl_cleanup(dir, index);
+			err = ovl_cleanup(ofs, dir, index);
 		}
 
 		if (err)

fs/overlayfs/super.c

@@ -184,7 +184,8 @@ static struct inode *ovl_alloc_inode(struct super_block *sb)
 	oi->version = 0;
 	oi->flags = 0;
 	oi->__upperdentry = NULL;
-	oi->lower = NULL;
+	oi->lowerpath.dentry = NULL;
+	oi->lowerpath.layer = NULL;
 	oi->lowerdata = NULL;
 	mutex_init(&oi->lock);
 
@@ -205,7 +206,7 @@ static void ovl_destroy_inode(struct inode *inode)
 	struct ovl_inode *oi = OVL_I(inode);
 
 	dput(oi->__upperdentry);
-	iput(oi->lower);
+	dput(oi->lowerpath.dentry);
 	if (S_ISDIR(inode->i_mode))
 		ovl_dir_cache_free(inode);
 	else
@@ -761,7 +762,7 @@ static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
 
 	inode_lock_nested(dir, I_MUTEX_PARENT);
 retry:
-	work = lookup_one_len(name, ofs->workbasedir, strlen(name));
+	work = ovl_lookup_upper(ofs, name, ofs->workbasedir, strlen(name));
 
 	if (!IS_ERR(work)) {
 		struct iattr attr = {
@@ -778,7 +779,7 @@ static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
 				goto out_unlock;
 
 			retried = true;
-			err = ovl_workdir_cleanup(dir, mnt, work, 0);
+			err = ovl_workdir_cleanup(ofs, dir, mnt, work, 0);
 			dput(work);
 			if (err == -EINVAL) {
 				work = ERR_PTR(err);
@@ -787,7 +788,7 @@ static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
 			goto retry;
 		}
 
-		err = ovl_mkdir_real(dir, &work, attr.ia_mode);
+		err = ovl_mkdir_real(ofs, dir, &work, attr.ia_mode);
 		if (err)
 			goto out_dput;
 
@@ -809,19 +810,19 @@ static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
 		 * allowed as upper are limited to "normal" ones, where checking
 		 * for the above two errors is sufficient.
 		 */
-		err = vfs_removexattr(&init_user_ns, work,
+		err = ovl_do_removexattr(ofs, work,
 					 XATTR_NAME_POSIX_ACL_DEFAULT);
 		if (err && err != -ENODATA && err != -EOPNOTSUPP)
 			goto out_dput;
 
-		err = vfs_removexattr(&init_user_ns, work,
+		err = ovl_do_removexattr(ofs, work,
 					 XATTR_NAME_POSIX_ACL_ACCESS);
 		if (err && err != -ENODATA && err != -EOPNOTSUPP)
 			goto out_dput;
 
 		/* Clear any inherited mode bits */
 		inode_lock(work->d_inode);
-		err = notify_change(&init_user_ns, work, &attr, NULL);
+		err = ovl_do_notify_change(ofs, work, &attr);
 		inode_unlock(work->d_inode);
 		if (err)
 			goto out_dput;
@@ -873,10 +874,6 @@ static int ovl_mount_dir_noesc(const char *name, struct path *path)
 		pr_err("filesystem on '%s' not supported\n", name);
 		goto out_put;
 	}
-	if (is_idmapped_mnt(path->mnt)) {
-		pr_err("idmapped layers are currently not supported\n");
-		goto out_put;
-	}
 	if (!d_is_dir(path->dentry)) {
 		pr_err("'%s' not a directory\n", name);
 		goto out_put;
@@ -1256,8 +1253,9 @@ static int ovl_get_upper(struct super_block *sb, struct ovl_fs *ofs,
  * Returns 1 if RENAME_WHITEOUT is supported, 0 if not supported and
  * negative values if error is encountered.
  */
-static int ovl_check_rename_whiteout(struct dentry *workdir)
+static int ovl_check_rename_whiteout(struct ovl_fs *ofs)
 {
+	struct dentry *workdir = ofs->workdir;
 	struct inode *dir = d_inode(workdir);
 	struct dentry *temp;
 	struct dentry *dest;
@@ -1267,12 +1265,12 @@ static int ovl_check_rename_whiteout(struct dentry *workdir)
 
 	inode_lock_nested(dir, I_MUTEX_PARENT);
 
-	temp = ovl_create_temp(workdir, OVL_CATTR(S_IFREG | 0));
+	temp = ovl_create_temp(ofs, workdir, OVL_CATTR(S_IFREG | 0));
 	err = PTR_ERR(temp);
 	if (IS_ERR(temp))
 		goto out_unlock;
 
-	dest = ovl_lookup_temp(workdir);
+	dest = ovl_lookup_temp(ofs, workdir);
 	err = PTR_ERR(dest);
 	if (IS_ERR(dest)) {
 		dput(temp);
@@ -1281,14 +1279,14 @@ static int ovl_check_rename_whiteout(struct dentry *workdir)
 
 	/* Name is inline and stable - using snapshot as a copy helper */
 	take_dentry_name_snapshot(&name, temp);
-	err = ovl_do_rename(dir, temp, dir, dest, RENAME_WHITEOUT);
+	err = ovl_do_rename(ofs, dir, temp, dir, dest, RENAME_WHITEOUT);
 	if (err) {
 		if (err == -EINVAL)
 			err = 0;
 		goto cleanup_temp;
 	}
 
-	whiteout = lookup_one_len(name.name.name, workdir, name.name.len);
+	whiteout = ovl_lookup_upper(ofs, name.name.name, workdir, name.name.len);
 	err = PTR_ERR(whiteout);
 	if (IS_ERR(whiteout))
 		goto cleanup_temp;
@@ -1297,11 +1295,11 @@ static int ovl_check_rename_whiteout(struct dentry *workdir)
 
 	/* Best effort cleanup of whiteout and temp file */
 	if (err)
-		ovl_cleanup(dir, whiteout);
+		ovl_cleanup(ofs, dir, whiteout);
 	dput(whiteout);
 
 cleanup_temp:
-	ovl_cleanup(dir, temp);
+	ovl_cleanup(ofs, dir, temp);
 	release_dentry_name_snapshot(&name);
 	dput(temp);
 	dput(dest);
@@ -1312,16 +1310,17 @@ static int ovl_check_rename_whiteout(struct dentry *workdir)
 	return err;
 }
 
-static struct dentry *ovl_lookup_or_create(struct dentry *parent,
+static struct dentry *ovl_lookup_or_create(struct ovl_fs *ofs,
+					   struct dentry *parent,
 					   const char *name, umode_t mode)
 {
 	size_t len = strlen(name);
 	struct dentry *child;
 
 	inode_lock_nested(parent->d_inode, I_MUTEX_PARENT);
-	child = lookup_one_len(name, parent, len);
+	child = ovl_lookup_upper(ofs, name, parent, len);
 	if (!IS_ERR(child) && !child->d_inode)
-		child = ovl_create_real(parent->d_inode, child,
+		child = ovl_create_real(ofs, parent->d_inode, child,
 					OVL_CATTR(mode));
 	inode_unlock(parent->d_inode);
 	dput(parent);
@@ -1343,7 +1342,7 @@ static int ovl_create_volatile_dirty(struct ovl_fs *ofs)
 	const char *const *name = volatile_path;
 
 	for (ctr = ARRAY_SIZE(volatile_path); ctr; ctr--, name++) {
-		d = ovl_lookup_or_create(d, *name, ctr > 1 ? S_IFDIR : S_IFREG);
+		d = ovl_lookup_or_create(ofs, d, *name, ctr > 1 ? S_IFDIR : S_IFREG);
 		if (IS_ERR(d))
 			return PTR_ERR(d);
 	}
@@ -1391,7 +1390,7 @@ static int ovl_make_workdir(struct super_block *sb, struct ovl_fs *ofs,
 		pr_warn("upper fs needs to support d_type.\n");
 
 	/* Check if upper/work fs supports O_TMPFILE */
-	temp = ovl_do_tmpfile(ofs->workdir, S_IFREG | 0);
+	temp = ovl_do_tmpfile(ofs, ofs->workdir, S_IFREG | 0);
 	ofs->tmpfile = !IS_ERR(temp);
 	if (ofs->tmpfile)
 		dput(temp);
@@ -1400,7 +1399,7 @@ static int ovl_make_workdir(struct super_block *sb, struct ovl_fs *ofs,
 
 
 	/* Check if upper/work fs supports RENAME_WHITEOUT */
-	err = ovl_check_rename_whiteout(ofs->workdir);
+	err = ovl_check_rename_whiteout(ofs);
 	if (err < 0)
 		goto out;
 
@@ -1411,7 +1410,7 @@ static int ovl_make_workdir(struct super_block *sb, struct ovl_fs *ofs,
 	/*
 	 * Check if upper/work fs supports (trusted|user).overlay.* xattr
 	 */
-	err = ovl_do_setxattr(ofs, ofs->workdir, OVL_XATTR_OPAQUE, "0", 1);
+	err = ovl_setxattr(ofs, ofs->workdir, OVL_XATTR_OPAQUE, "0", 1);
 	if (err) {
 		ofs->noxattr = true;
 		if (ofs->config.index || ofs->config.metacopy) {
@@ -1429,7 +1428,7 @@ static int ovl_make_workdir(struct super_block *sb, struct ovl_fs *ofs,
 		}
 		err = 0;
 	} else {
-		ovl_do_removexattr(ofs, ofs->workdir, OVL_XATTR_OPAQUE);
+		ovl_removexattr(ofs, ofs->workdir, OVL_XATTR_OPAQUE);
 	}
 
 	/*

fs/overlayfs/util.c

@@ -194,6 +194,20 @@ enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)
 	return type;
 }
 
+enum ovl_path_type ovl_path_realdata(struct dentry *dentry, struct path *path)
+{
+	enum ovl_path_type type = ovl_path_type(dentry);
+
+	WARN_ON_ONCE(d_is_dir(dentry));
+
+	if (!OVL_TYPE_UPPER(type) || OVL_TYPE_MERGE(type))
+		ovl_path_lowerdata(dentry, path);
+	else
+		ovl_path_upper(dentry, path);
+
+	return type;
+}
+
 struct dentry *ovl_dentry_upper(struct dentry *dentry)
 {
 	return ovl_upperdentry_dereference(OVL_I(d_inode(dentry)));
@@ -236,6 +250,17 @@ struct dentry *ovl_i_dentry_upper(struct inode *inode)
 	return ovl_upperdentry_dereference(OVL_I(inode));
 }
 
+void ovl_i_path_real(struct inode *inode, struct path *path)
+{
+	path->dentry = ovl_i_dentry_upper(inode);
+	if (!path->dentry) {
+		path->dentry = OVL_I(inode)->lowerpath.dentry;
+		path->mnt = OVL_I(inode)->lowerpath.layer->mnt;
+	} else {
+		path->mnt = ovl_upper_mnt(OVL_FS(inode->i_sb));
+	}
+}
+
 struct inode *ovl_inode_upper(struct inode *inode)
 {
 	struct dentry *upperdentry = ovl_i_dentry_upper(inode);
@@ -245,7 +270,9 @@ struct inode *ovl_inode_upper(struct inode *inode)
 
 struct inode *ovl_inode_lower(struct inode *inode)
 {
-	return OVL_I(inode)->lower;
+	struct dentry *lowerdentry = OVL_I(inode)->lowerpath.dentry;
+
+	return lowerdentry ? d_inode(lowerdentry) : NULL;
 }
 
 struct inode *ovl_inode_real(struct inode *inode)
@@ -443,7 +470,7 @@ static void ovl_dir_version_inc(struct dentry *dentry, bool impurity)
 void ovl_dir_modified(struct dentry *dentry, bool impurity)
 {
 	/* Copy mtime/ctime */
-	ovl_copyattr(d_inode(ovl_dentry_upper(dentry)), d_inode(dentry));
+	ovl_copyattr(d_inode(dentry));
 
 	ovl_dir_version_inc(dentry, impurity);
 }
@@ -466,6 +493,7 @@ bool ovl_is_whiteout(struct dentry *dentry)
 struct file *ovl_path_open(struct path *path, int flags)
 {
 	struct inode *inode = d_inode(path->dentry);
+	struct user_namespace *real_mnt_userns = mnt_user_ns(path->mnt);
 	int err, acc_mode;
 
 	if (flags & ~(O_ACCMODE | O_LARGEFILE))
@@ -482,12 +510,12 @@ struct file *ovl_path_open(struct path *path, int flags)
 		BUG();
 	}
 
-	err = inode_permission(&init_user_ns, inode, acc_mode | MAY_OPEN);
+	err = inode_permission(real_mnt_userns, inode, acc_mode | MAY_OPEN);
 	if (err)
 		return ERR_PTR(err);
 
 	/* O_NOATIME is an optimization, don't fail if not permitted */
-	if (inode_owner_or_capable(&init_user_ns, inode))
+	if (inode_owner_or_capable(real_mnt_userns, inode))
 		flags |= O_NOATIME;
 
 	return dentry_open(path, flags, current_cred());
@@ -550,11 +578,11 @@ void ovl_copy_up_end(struct dentry *dentry)
 	ovl_inode_unlock(d_inode(dentry));
 }
 
-bool ovl_check_origin_xattr(struct ovl_fs *ofs, struct dentry *dentry)
+bool ovl_path_check_origin_xattr(struct ovl_fs *ofs, struct path *path)
 {
 	int res;
 
-	res = ovl_do_getxattr(ofs, dentry, OVL_XATTR_ORIGIN, NULL, 0);
+	res = ovl_path_getxattr(ofs, path, OVL_XATTR_ORIGIN, NULL, 0);
 
 	/* Zero size value means "copied up but origin unknown" */
 	if (res >= 0)
@@ -563,16 +591,16 @@ bool ovl_check_origin_xattr(struct ovl_fs *ofs, struct dentry *dentry)
 	return false;
 }
 
-bool ovl_check_dir_xattr(struct super_block *sb, struct dentry *dentry,
+bool ovl_path_check_dir_xattr(struct ovl_fs *ofs, struct path *path,
 			       enum ovl_xattr ox)
 {
 	int res;
 	char val;
 
-	if (!d_is_dir(dentry))
+	if (!d_is_dir(path->dentry))
 		return false;
 
-	res = ovl_do_getxattr(OVL_FS(sb), dentry, ox, &val, 1);
+	res = ovl_path_getxattr(ofs, path, ox, &val, 1);
 	if (res == 1 && val == 'y')
 		return true;
 
@@ -612,7 +640,7 @@ int ovl_check_setxattr(struct ovl_fs *ofs, struct dentry *upperdentry,
 	if (ofs->noxattr)
 		return xerr;
 
-	err = ovl_do_setxattr(ofs, upperdentry, ox, value, size);
+	err = ovl_setxattr(ofs, upperdentry, ox, value, size);
 
 	if (err == -EOPNOTSUPP) {
 		pr_warn("cannot set %s xattr on upper\n", ovl_xattr(ofs, ox));
@@ -652,7 +680,7 @@ void ovl_check_protattr(struct inode *inode, struct dentry *upper)
 	char buf[OVL_PROTATTR_MAX+1];
 	int res, n;
 
-	res = ovl_do_getxattr(ofs, upper, OVL_XATTR_PROTATTR, buf,
+	res = ovl_getxattr_upper(ofs, upper, OVL_XATTR_PROTATTR, buf,
 				 OVL_PROTATTR_MAX);
 	if (res < 0)
 		return;
@@ -708,7 +736,7 @@ int ovl_set_protattr(struct inode *inode, struct dentry *upper,
 		err = ovl_check_setxattr(ofs, upper, OVL_XATTR_PROTATTR,
 					 buf, len, -EPERM);
 	} else if (inode->i_flags & OVL_PROT_I_FLAGS_MASK) {
-		err = ovl_do_removexattr(ofs, upper, OVL_XATTR_PROTATTR);
+		err = ovl_removexattr(ofs, upper, OVL_XATTR_PROTATTR);
 		if (err == -EOPNOTSUPP || err == -ENODATA)
 			err = 0;
 	}
@@ -824,7 +852,7 @@ static void ovl_cleanup_index(struct dentry *dentry)
 	}
 
 	inode_lock_nested(dir, I_MUTEX_PARENT);
-	index = lookup_one_len(name.name, indexdir, name.len);
+	index = ovl_lookup_upper(ofs, name.name, indexdir, name.len);
 	err = PTR_ERR(index);
 	if (IS_ERR(index)) {
 		index = NULL;
@@ -834,7 +862,7 @@ static void ovl_cleanup_index(struct dentry *dentry)
 					       dir, index);
 	} else {
 		/* Cleanup orphan index entries */
-		err = ovl_cleanup(dir, index);
+		err = ovl_cleanup(ofs, dir, index);
 	}
 
 	inode_unlock(dir);
@@ -943,15 +971,15 @@ int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir)
 }
 
 /* err < 0, 0 if no metacopy xattr, 1 if metacopy xattr found */
-int ovl_check_metacopy_xattr(struct ovl_fs *ofs, struct dentry *dentry)
+int ovl_check_metacopy_xattr(struct ovl_fs *ofs, struct path *path)
 {
 	int res;
 
 	/* Only regular files can have metacopy xattr */
-	if (!S_ISREG(d_inode(dentry)->i_mode))
+	if (!S_ISREG(d_inode(path->dentry)->i_mode))
 		return 0;
 
-	res = ovl_do_getxattr(ofs, dentry, OVL_XATTR_METACOPY, NULL, 0);
+	res = ovl_path_getxattr(ofs, path, OVL_XATTR_METACOPY, NULL, 0);
 	if (res < 0) {
 		if (res == -ENODATA || res == -EOPNOTSUPP)
 			return 0;
@@ -987,13 +1015,12 @@ bool ovl_is_metacopy_dentry(struct dentry *dentry)
 	return (oe->numlower > 1);
 }
 
-char *ovl_get_redirect_xattr(struct ovl_fs *ofs, struct dentry *dentry,
-			     int padding)
+char *ovl_get_redirect_xattr(struct ovl_fs *ofs, struct path *path, int padding)
 {
 	int res;
 	char *s, *next, *buf = NULL;
 
-	res = ovl_do_getxattr(ofs, dentry, OVL_XATTR_REDIRECT, NULL, 0);
+	res = ovl_path_getxattr(ofs, path, OVL_XATTR_REDIRECT, NULL, 0);
 	if (res == -ENODATA || res == -EOPNOTSUPP)
 		return NULL;
 	if (res < 0)
@@ -1005,7 +1032,7 @@ char *ovl_get_redirect_xattr(struct ovl_fs *ofs, struct dentry *dentry,
 	if (!buf)
 		return ERR_PTR(-ENOMEM);
 
-	res = ovl_do_getxattr(ofs, dentry, OVL_XATTR_REDIRECT, buf, res);
+	res = ovl_path_getxattr(ofs, path, OVL_XATTR_REDIRECT, buf, res);
 	if (res < 0)
 		goto fail;
 	if (res == 0)
@@ -1060,3 +1087,33 @@ int ovl_sync_status(struct ovl_fs *ofs)
 
 	return errseq_check(&mnt->mnt_sb->s_wb_err, ofs->errseq);
 }
+
+/*
+ * ovl_copyattr() - copy inode attributes from layer to ovl inode
+ *
+ * When overlay copies inode information from an upper or lower layer to the
+ * relevant overlay inode it will apply the idmapping of the upper or lower
+ * layer when doing so ensuring that the ovl inode ownership will correctly
+ * reflect the ownership of the idmapped upper or lower layer. For example, an
+ * idmapped upper or lower layer mapping id 1001 to id 1000 will take care to
+ * map any lower or upper inode owned by id 1001 to id 1000. These mapping
+ * helpers are nops when the relevant layer isn't idmapped.
+ */
+void ovl_copyattr(struct inode *inode)
+{
+	struct path realpath;
+	struct inode *realinode;
+	struct user_namespace *real_mnt_userns;
+
+	ovl_i_path_real(inode, &realpath);
+	realinode = d_inode(realpath.dentry);
+	real_mnt_userns = mnt_user_ns(realpath.mnt);
+
+	inode->i_uid = i_uid_into_mnt(real_mnt_userns, realinode);
+	inode->i_gid = i_gid_into_mnt(real_mnt_userns, realinode);
+	inode->i_mode = realinode->i_mode;
+	inode->i_atime = realinode->i_atime;
+	inode->i_mtime = realinode->i_mtime;
+	inode->i_ctime = realinode->i_ctime;
+	i_size_write(inode, i_size_read(realinode));
+}

include/linux/namei.h

@@ -69,6 +69,12 @@ extern struct dentry *lookup_one_len(const char *, struct dentry *, int);
 extern struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int);
 extern struct dentry *lookup_positive_unlocked(const char *, struct dentry *, int);
 struct dentry *lookup_one(struct user_namespace *, const char *, struct dentry *, int);
+struct dentry *lookup_one_unlocked(struct user_namespace *mnt_userns,
+				   const char *name, struct dentry *base,
+				   int len);
+struct dentry *lookup_one_positive_unlocked(struct user_namespace *mnt_userns,
+					    const char *name,
+					    struct dentry *base, int len);
 
 extern int follow_down_one(struct path *);
 extern int follow_down(struct path *);