Remove orphan GridFS chunks from MongoDB

cleanup.js

var i = 0; 
var orphans = 0;
db.fs.chunks.find({}, { files_id: 1 }).forEach(function(chunk) { 
    i++; 
    if (i % 100 === 0) {
        print(i); 
    }
    if (!db.fs.files.findOne({ _id: chunk.files_id }, { _id: 1 })) { 
        print("orphan " + chunk._id); 
        db.fs.chunks.remove({ _id: chunk._id }); 
        orphans++;
    }
});
print("done, " + orphans + " orphans deleted");