The general error logic handling in there is:

	*errp = -EFOO;
	<lots of code>
	if (some_error)
		goto out;

this is fragile and unmaintainable, because the setting of the error code is
"far away" from the site where the error was detected.

And the code was actually wrong - we're returning ENOSPC in places where fs
metadata inconsistency was detected.  We traditionally return -EIO in this
case.

So change it all to do, effectively:

	if (some_error) {
		*errp = -EFOO;
		goto out;
	}