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filter is not described

pre_get_space_used filter-hook . WP 3.5.0

Filters the amount of storage space used by the current site.

Usage

add_filter( 'pre_get_space_used', 'filter_function_name_7328' );
function filter_function_name_7328( $space_used ){
	// filter...

	return $space_used;
}
$space_used(int/true/false)
The amount of used space, in megabytes.
Default: false

Where the hook is called

get_space_used()
wp-includes/ms-functions.php 2423
$space_used = apply_filters( 'pre_get_space_used', false );

Where the hook is used (in WP core)

Does not used.