JimfsFileChannel the method read why need synchronized

[SailCoding]

public int read(ByteBuffer dst) throws IOException {
checkNotNull(dst);
checkOpen();
checkReadable();

int read = 0; // will definitely either be assigned or an exception will be thrown

// the synchronized can be deleted ???
synchronized (this) {
boolean completed = false;
try {
if (!beginBlocking()) {
return 0; // AsynchronousCloseException will be thrown
}
file.readLock().lockInterruptibly();
try {
read = file.read(position, dst);
if (read != -1) {
position += read;
}
file.updateAccessTime();
completed = true;
} finally {
file.readLock().unlock();
}
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
} finally {
endBlocking(completed);
}
}

return read;

}