Re: [PATCH 8/9] fs: don't allow kernel reads and writes without iter ops

[Christoph Hellwig]

On Fri, Jun 26, 2020 at 02:51:47PM +0100, Matthew Wilcox wrote:
> On Fri, Jun 26, 2020 at 09:58:35AM +0200, Christoph Hellwig wrote:
> > +static void warn_unsupported(struct file *file, const char *op)
> > +{
> > +	char pathname[128], *path;
> > +
> > +	path = file_path(file, pathname, sizeof(pathname));
> > +	if (IS_ERR(path))
> > +		path = "(unknown)";
> > +	pr_warn_ratelimited(
> > +		"kernel %s not supported for file %s (pid: %d comm: %.20s)\n",
> > +		op, path, current->pid, current->comm);
> > +}
> > +
> 
> how about just:
> 
> 	pr_warn_ratelimited(
> 		"kernel %s not supported for file %pD4 (pid: %d comm: %.20s)\n",
> 			op, file, current->pid, current->comm);

Sure, we could use %pD for a few less line of code and a little less
typesafety.  I'm not a huge fan of these custom, unchecked format
specifiers, but given that they exist we might a well use them.