mtd
MTD device structure
fsbuf
buffer given by fs driver
oobsel
out of band selection structre
autoplace
1 = place given buffer into the oob bytes
numpages
number of pages to prepare
1. Filesystem buffer available and autoplacement is off, return filesystem buffer 2. No filesystem buffer or autoplace is off, return internal buffer 3. Filesystem buffer is given and autoplace selected put data from fs buffer into internal buffer and retrun internal buffer