public synchronized void releaseImmediate(FileSystemRef ref) {
		FSRLRoot fsFSRL = ref.getFilesystem().getFSRL();
		FSCacheInfo fsci = filesystems.get(fsFSRL);
		ref.close();
		if (fsci == null) {
			if (!rootFSRL.equals(fsFSRL) /* we don't store root FS refs */) {
				Msg.warn(this, "Unknown file system reference: " + fsFSRL);
			}
			return;
		}
		FileSystemRefManager refManager = fsci.ref.getFilesystem().getRefManager();
		if (refManager.canClose(fsci.ref)) {
			release(fsci);
		}

	}
Closes the specified ref, and if no other refs to the file system remain, closes the file system.
 
@param ref {@link FileSystemRef} to close
Ghidra/Features/Base/src/main/java/ghidra/formats/gfilesystem/FileSystemInstanceManager.java