This patch changes cont_prepare_write(), in order to support a 4G-1
file for FAT32.

 int cont_prepare_write(struct page *page, unsigned offset,
-		unsigned to, get_block_t *get_block, unsigned long *bytes)
+		unsigned to, get_block_t *get_block, loff_t *bytes)

And it fixes broken adfs/affs/fat/hfs/hpfs/qnx4 by this
cont_prepare_write() change.