well here is what I,m doing:

patch -p1 < disk-io.patch  
output: "patching file fs/btrfs/disk-io.c"
rmmod btrfs 
rmmod lzo_compress
make -j3
make -j3 modules
make -j3 modules_install
cp arch/x86_64/boot/bzImage /boot/linux-next
depmod -a

(reboot)
modprobe btrfs
btrfs device scan
btrfs filesystem show (all drives show)
mount -o ro /dev/sdb1 /btrfs

and the output is : 

[ 4364.813453] parent transid verify failed on 2206281838592 wanted 2135 found 
1545
[ 4364.817093] btrfs: open_ctree failed
 

I checked the resulting disk-io.c file and the changes were merged. as you can
see I rebuilt my kernel and modules, rebooted and still got this error. is there
a step I'm missing? 

thanks