ovl: use stub posix acl handlers

Now that ovl supports the get and set acl inode operations and the vfs
has been switched to the new posi api, ovl can simply rely on the stub
posix acl handlers. The custom xattr handlers and associated unused
helpers can be removed.
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

fs/overlayfs/super.c

@@ -999,83 +999,6 @@ static unsigned int ovl_split_lowerdirs(char *str)
 	return ctr;
 }
 
-static int __maybe_unused
-ovl_posix_acl_xattr_get(const struct xattr_handler *handler,
-			struct dentry *dentry, struct inode *inode,
-			const char *name, void *buffer, size_t size)
-{
-	return ovl_xattr_get(dentry, inode, handler->name, buffer, size);
-}
-
-static int __maybe_unused
-ovl_posix_acl_xattr_set(const struct xattr_handler *handler,
-			struct user_namespace *mnt_userns,
-			struct dentry *dentry, struct inode *inode,
-			const char *name, const void *value,
-			size_t size, int flags)
-{
-	struct dentry *workdir = ovl_workdir(dentry);
-	struct inode *realinode = ovl_inode_real(inode);
-	struct posix_acl *acl = NULL;
-	int err;
-
-	/* Check that everything is OK before copy-up */
-	if (value) {
-		/* The above comment can be understood in two ways:
-		 *
-		 * 1. We just want to check whether the basic POSIX ACL format
-		 *    is ok. For example, if the header is correct and the size
-		 *    is sane.
-		 * 2. We want to know whether the ACL_{GROUP,USER} entries can
-		 *    be mapped according to the underlying filesystem.
-		 *
-		 * Currently, we only check 1. If we wanted to check 2. we
-		 * would need to pass the mnt_userns and the fs_userns of the
-		 * underlying filesystem. But frankly, I think checking 1. is
-		 * enough to start the copy-up.
-		 */
-		acl = vfs_set_acl_prepare(&init_user_ns, &init_user_ns, value, size);
-		if (IS_ERR(acl))
-			return PTR_ERR(acl);
-	}
-	err = -EOPNOTSUPP;
-	if (!IS_POSIXACL(d_inode(workdir)))
-		goto out_acl_release;
-	if (!realinode->i_op->set_acl)
-		goto out_acl_release;
-	if (handler->flags == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) {
-		err = acl ? -EACCES : 0;
-		goto out_acl_release;
-	}
-	err = -EPERM;
-	if (!inode_owner_or_capable(&init_user_ns, inode))
-		goto out_acl_release;
-
-	posix_acl_release(acl);
-
-	/*
-	 * Check if sgid bit needs to be cleared (actual setacl operation will
-	 * be done with mounter's capabilities and so that won't do it for us).
-	 */
-	if (unlikely(inode->i_mode & S_ISGID) &&
-	    handler->flags == ACL_TYPE_ACCESS &&
-	    !in_group_p(inode->i_gid) &&
-	    !capable_wrt_inode_uidgid(&init_user_ns, inode, CAP_FSETID)) {
-		struct iattr iattr = { .ia_valid = ATTR_KILL_SGID };
-
-		err = ovl_setattr(&init_user_ns, dentry, &iattr);
-		if (err)
-			return err;
-	}
-
-	err = ovl_xattr_set(dentry, inode, handler->name, value, size, flags);
-	return err;
-
-out_acl_release:
-	posix_acl_release(acl);
-	return err;
-}
-
 static int ovl_own_xattr_get(const struct xattr_handler *handler,
 			     struct dentry *dentry, struct inode *inode,
 			     const char *name, void *buffer, size_t size)
@@ -1108,22 +1031,6 @@ static int ovl_other_xattr_set(const struct xattr_handler *handler,
 	return ovl_xattr_set(dentry, inode, name, value, size, flags);
 }
 
-static const struct xattr_handler __maybe_unused
-ovl_posix_acl_access_xattr_handler = {
-	.name = XATTR_NAME_POSIX_ACL_ACCESS,
-	.flags = ACL_TYPE_ACCESS,
-	.get = ovl_posix_acl_xattr_get,
-	.set = ovl_posix_acl_xattr_set,
-};
-
-static const struct xattr_handler __maybe_unused
-ovl_posix_acl_default_xattr_handler = {
-	.name = XATTR_NAME_POSIX_ACL_DEFAULT,
-	.flags = ACL_TYPE_DEFAULT,
-	.get = ovl_posix_acl_xattr_get,
-	.set = ovl_posix_acl_xattr_set,
-};
-
 static const struct xattr_handler ovl_own_trusted_xattr_handler = {
 	.prefix	= OVL_XATTR_TRUSTED_PREFIX,
 	.get = ovl_own_xattr_get,
@@ -1144,8 +1051,8 @@ static const struct xattr_handler ovl_other_xattr_handler = {
 
 static const struct xattr_handler *ovl_trusted_xattr_handlers[] = {
 #ifdef CONFIG_FS_POSIX_ACL
-	&ovl_posix_acl_access_xattr_handler,
-	&ovl_posix_acl_default_xattr_handler,
+	&posix_acl_access_xattr_handler,
+	&posix_acl_default_xattr_handler,
 #endif
 	&ovl_own_trusted_xattr_handler,
 	&ovl_other_xattr_handler,
@@ -1154,8 +1061,8 @@ static const struct xattr_handler *ovl_trusted_xattr_handlers[] = {
 
 static const struct xattr_handler *ovl_user_xattr_handlers[] = {
 #ifdef CONFIG_FS_POSIX_ACL
-	&ovl_posix_acl_access_xattr_handler,
-	&ovl_posix_acl_default_xattr_handler,
+	&posix_acl_access_xattr_handler,
+	&posix_acl_default_xattr_handler,
 #endif
 	&ovl_own_user_xattr_handler,
 	&ovl_other_xattr_handler,