using nginx to save incoming data/request to file

i am looking for a solution to save data sent via http (e.g. as a POST) as quickly as possible (with lowest overhead) via nginx (v1.2.9). i tried the following nginx configuration, but am not seeing any files written in the directory:

server {
listen 9199;
location /saveme {
client_body_in_file_only on;
client_body_temp_path /tmp/bodies;
}
}

what am i doing wrong? and/or is there a better way to accomplish this? (the data that is written should ideally be one file per request, and it does not matter if it is fairly "raw" in nature. post-processing of the files will be done via a separate process via a queue.)