This time, the full version of FatFS library, but for PIC18F27J53 microcontroller. The library is adapted by @spinnaker and posted on "All About Circuits" forums. Go to "Microchip MDD File System" thread and from the second post you will be able to download the archive containing his project.
Of course, you'll have to subscribe in order to download the file. In the linker script you'll see three protected zones for the bigger arrays FatFS needs. Many thanks @spinnaker!