You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: gc_unix.go
    path of file: ./repos/moby/builder/builder-next/worker
    
    the code of the file until where you have to start completion: //go:build !windows

package worker

import (
	"syscall"
)

func detec
    
func detectDefaultGCCap(root string) int64 {
	var st syscall.Statfs_t
	if err := syscall.Statfs(root, &st); err != nil {
		return defaultCap
	}
	diskSize := int64(st.Bsize) * int64(st.Blocks) //nolint unconvert
	avail := diskSize / 10
	return (avail/(1<<30) + 1) * 1e9 // round up
}