fs: make posix_acl_chmod more useful

Rename the current posix_acl_chmod to __posix_acl_chmod and add
a fully featured ACL chmod helper that uses the ->set_acl inode
operation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index e699b07..0821855 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -364,7 +364,7 @@
 /*
  * Modify the ACL for the chmod syscall.
  */
-static int posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode)
+static int __posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode)
 {
 	struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
 	struct posix_acl_entry *pa, *pe;
@@ -428,12 +428,12 @@
 EXPORT_SYMBOL(posix_acl_create);
 
 int
-posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode)
+__posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode)
 {
 	struct posix_acl *clone = posix_acl_clone(*acl, gfp);
 	int err = -ENOMEM;
 	if (clone) {
-		err = posix_acl_chmod_masq(clone, mode);
+		err = __posix_acl_chmod_masq(clone, mode);
 		if (err) {
 			posix_acl_release(clone);
 			clone = NULL;
@@ -443,6 +443,30 @@
 	*acl = clone;
 	return err;
 }
+EXPORT_SYMBOL(__posix_acl_chmod);
+
+int
+posix_acl_chmod(struct inode *inode)
+{
+	struct posix_acl *acl;
+	int ret = 0;
+
+	if (!IS_POSIXACL(inode))
+		return 0;
+	if (!inode->i_op->set_acl)
+		return -EOPNOTSUPP;
+
+	acl = get_acl(inode, ACL_TYPE_ACCESS);
+	if (IS_ERR_OR_NULL(acl))
+		return PTR_ERR(acl);
+
+	ret = __posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
+	if (ret)
+		return ret;
+	ret = inode->i_op->set_acl(inode, acl, ACL_TYPE_ACCESS);
+	posix_acl_release(acl);
+	return ret;
+}
 EXPORT_SYMBOL(posix_acl_chmod);
 
 /*