[U-Boot-Users] Suggestion on CRCing data on NAND?

I need to calculate CRC for the data (jffs2) on NAND flash. (u-boot is on separate NOR flash, btw.) What do you all think is the best way to do so? I'm guessing that I need to do the nand read.jffs2 and then perform CRC on that data where its read.

Can anyone suggest a better/faster way?