[PATCH 4/5] repair: don't cache large blkmap allocations

[Christoph Hellwig]

> +	/* consider more than 100k extents rare */
> +	if (blkmap->naexts < 100 * 1024)
> +		return;

100k extents still seems like a fairly high number.  Otherwise looks
okay.

(If only we had a non-sucky threaded memory allocator in userspace..)