private void ensureAvailableSpace(long sizeHint) throws IOException {
		if (cacheDirFileStore != null && sizeHint > MAX_INMEM_FILESIZE) {
			long usableSpace = cacheDirFileStore.getUsableSpace();
			if (usableSpace >= 0 && usableSpace < sizeHint + FREESPACE_RESERVE_BYTES) {
				throw new IOException("Not enough storage available in " + cacheDir +
					" to store file sized: " + sizeHint);
			}
		}
		
	}
Deletes all stored files from this file cache that are under a "NN" two hex digit
nesting dir.
<p>
Will cause other processes which are accessing or updating the cache to error.
Ghidra/Features/Base/src/main/java/ghidra/formats/gfilesystem/FileCache.java