I have a working AT45DB and SST26VF driver I made and successfully implemented it for elm chan's FAT-FS. But as you know a NOR or NAND flash will wear out after 100,000 write cycles, so I have to include wear leveling to increase it "lifetime". Do you know of any open source middleware wear leveling block? I found Spiff, which is a file system with wear leveling included. But I was hoping to use Chan's FS as it is well maintained and quite robust.
If you are using a Dataflash use a flash file system (YAFFS, SPIFFS, NIFFS) or any other. As @hassan789 said, FAT does not journal.