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/ext3/acl.c b/fs/ext3/acl.c
index dbb5ad5..6691a6c 100644
--- a/fs/ext3/acl.c
+++ b/fs/ext3/acl.c
@@ -314,7 +314,7 @@
 	acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
 	if (IS_ERR(acl) || !acl)
 		return PTR_ERR(acl);
-	error = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
+	error = __posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
 	if (error)
 		return error;
 retry: