kubernetes/vendor/go.etcd.io/etcd/client/pkg/v3/fileutil/preallocate.go

// Preallocate tries to allocate the space for given
// file. This operation is only supported on linux by a
// few filesystems (btrfs, ext4, etc.).
// If the operation is unsupported, no error will be returned.
// Otherwise, the error encountered will be returned.
func Preallocate(f *os.File, sizeInBytes int64, extendFile bool) error { … }

func preallocExtendTrunc(f *os.File, sizeInBytes int64) error { … }