Grub2 is going to support btrfs someday, so better getting prepared.
MODULES_USB="ehci-hcd uhci usb-ohci hid usb-storage uhci-hcd ohci-hcd usbhid sl811-hcd hid-a4tech hid-apple hid-belkin hid-cherry hid-chicony hid-cypress hid-dummy hid-ezkey hid-gyration hid-logitech hid-microsoft hid-monterey hid-petalynx hid-pl hid-samsung hid-sony hid-sunplus"
# Filesystems
-MODULES_FS="ext2 ext3 ext4 reiserfs jfs nfs xfs fuse"
+MODULES_FS="ext2 ext3 ext4 btrfs reiserfs jfs nfs xfs fuse"
MODULES_USB="ehci-hcd uhci usb-ohci hid usb-storage uhci-hcd ohci-hcd usbhid sl811-hcd hid-a4tech hid-apple hid-belkin hid-cherry hid-chicony hid-cypress hid-dummy hid-ezkey hid-gyration hid-logitech hid-microsoft hid-monterey hid-petalynx hid-pl hid-samsung hid-sony hid-sunplus"
# Filesystems
-MODULES_FS="ext2 ext3 ext4 reiserfs jfs nfs xfs fuse"
+MODULES_FS="ext2 ext3 ext4 btrfs reiserfs jfs nfs xfs fuse"
MODULES_USB="ehci-hcd uhci usb-ohci hid usb-storage uhci-hcd ohci-hcd usbhid sl811-hcd hid-a4tech hid-apple hid-belkin hid-cherry hid-chicony hid-cypress hid-dummy hid-ezkey hid-gyration hid-logitech hid-microsoft hid-monterey hid-petalynx hid-pl hid-samsung hid-sony hid-sunplus"
# Filesystems
-MODULES_FS="ext2 ext3 ext4 reiserfs jfs nfs xfs fuse"
+MODULES_FS="ext2 ext3 ext4 btrfs reiserfs jfs nfs xfs fuse"
MODULES_USB="ehci-hcd uhci usb-ohci hid usb-storage uhci-hcd ohci-hcd usbhid sl811-hcd hid-a4tech hid-apple hid-belkin hid-cherry hid-chicony hid-cypress hid-dummy hid-ezkey hid-gyration hid-logitech hid-microsoft hid-monterey hid-petalynx hid-pl hid-samsung hid-sony hid-sunplus"
# Filesystems
-MODULES_FS="ext2 ext3 ext4 reiserfs jfs nfs xfs fuse"
+MODULES_FS="ext2 ext3 ext4 btrfs reiserfs jfs nfs xfs fuse"
MODULES_USB="ehci-hcd uhci usb-ohci hid usb-storage uhci-hcd ohci-hcd usbhid sl811-hcd hid-a4tech hid-apple hid-belkin hid-cherry hid-chicony hid-cypress hid-dummy hid-ezkey hid-gyration hid-logitech hid-microsoft hid-monterey hid-petalynx hid-pl hid-samsung hid-sony hid-sunplus"
# Filesystems
-MODULES_FS="ext2 ext3 ext4 reiserfs jfs nfs xfs fuse"
+MODULES_FS="ext2 ext3 ext4 btrfs reiserfs jfs nfs xfs fuse"
MODULES_USB="ehci-hcd uhci usb-ohci hid usb-storage uhci-hcd ohci-hcd usbhid sl811-hcd hid-a4tech hid-apple hid-belkin hid-cherry hid-chicony hid-cypress hid-dummy hid-ezkey hid-gyration hid-logitech hid-microsoft hid-monterey hid-petalynx hid-pl hid-samsung hid-sony hid-sunplus"
# Filesystems
-MODULES_FS="ext2 ext3 ext4 reiserfs jfs nfs xfs fuse"
+MODULES_FS="ext2 ext3 ext4 btrfs reiserfs jfs nfs xfs fuse"
MODULES_USB="ehci-hcd uhci usb-ohci hid usb-storage uhci-hcd ohci-hcd usbhid sl811-hcd hid-a4tech hid-apple hid-belkin hid-cherry hid-chicony hid-cypress hid-dummy hid-ezkey hid-gyration hid-logitech hid-microsoft hid-monterey hid-petalynx hid-pl hid-samsung hid-sony hid-sunplus"
# Filesystems
-MODULES_FS="ext2 ext3 ext4 reiserfs jfs nfs xfs fuse"
+MODULES_FS="ext2 ext3 ext4 btrfs reiserfs jfs nfs xfs fuse"
MODULES_USB="ehci-hcd uhci usb-ohci hid usb-storage uhci-hcd ohci-hcd usbhid sl811-hcd hid-a4tech hid-apple hid-belkin hid-cherry hid-chicony hid-cypress hid-dummy hid-ezkey hid-gyration hid-logitech hid-microsoft hid-monterey hid-petalynx hid-pl hid-samsung hid-sony hid-sunplus"
# Filesystems
-MODULES_FS="ext2 ext3 ext4 reiserfs jfs nfs xfs fuse"
+MODULES_FS="ext2 ext3 ext4 btrfs reiserfs jfs nfs xfs fuse"
MODULES_USB="ehci-hcd uhci usb-ohci hid usb-storage uhci-hcd ohci-hcd usbhid sl811-hcd hid-a4tech hid-apple hid-belkin hid-cherry hid-chicony hid-cypress hid-dummy hid-ezkey hid-gyration hid-logitech hid-microsoft hid-monterey hid-petalynx hid-pl hid-samsung hid-sony hid-sunplus"
# Filesystems
-MODULES_FS="ext2 ext3 ext4 reiserfs jfs nfs xfs fuse"
+MODULES_FS="ext2 ext3 ext4 btrfs reiserfs jfs nfs xfs fuse"
MODULES_USB="ehci-hcd uhci usb-ohci hid usb-storage uhci-hcd ohci-hcd usbhid sl811-hcd hid-a4tech hid-apple hid-belkin hid-cherry hid-chicony hid-cypress hid-dummy hid-ezkey hid-gyration hid-logitech hid-microsoft hid-monterey hid-petalynx hid-pl hid-samsung hid-sony hid-sunplus"
# Filesystems
-MODULES_FS="ext2 ext3 ext4 reiserfs jfs nfs xfs fuse"
+MODULES_FS="ext2 ext3 ext4 btrfs reiserfs jfs nfs xfs fuse"
MODULES_USB="ehci-hcd uhci usb-ohci hid usb-storage uhci-hcd ohci-hcd usbhid sl811-hcd hid-a4tech hid-apple hid-belkin hid-cherry hid-chicony hid-cypress hid-dummy hid-ezkey hid-gyration hid-logitech hid-microsoft hid-monterey hid-petalynx hid-pl hid-samsung hid-sony hid-sunplus"
# Filesystems
-MODULES_FS="ext2 ext3 ext4 reiserfs jfs nfs xfs fuse"
+MODULES_FS="ext2 ext3 ext4 btrfs reiserfs jfs nfs xfs fuse"
MODULES_USB="ehci-hcd uhci usb-ohci hid usb-storage uhci-hcd ohci-hcd usbhid sl811-hcd hid-a4tech hid-apple hid-belkin hid-cherry hid-chicony hid-cypress hid-dummy hid-ezkey hid-gyration hid-logitech hid-microsoft hid-monterey hid-petalynx hid-pl hid-samsung hid-sony hid-sunplus"
# Filesystems
-MODULES_FS="ext2 ext3 ext4 reiserfs jfs nfs xfs fuse"
+MODULES_FS="ext2 ext3 ext4 btrfs reiserfs jfs nfs xfs fuse"
MODULES_USB="ehci-hcd uhci usb-ohci hid usb-storage uhci-hcd ohci-hcd usbhid sl811-hcd hid-a4tech hid-apple hid-belkin hid-cherry hid-chicony hid-cypress hid-dummy hid-ezkey hid-gyration hid-logitech hid-microsoft hid-monterey hid-petalynx hid-pl hid-samsung hid-sony hid-sunplus"
# Filesystems
-MODULES_FS="ext2 ext3 ext4 reiserfs jfs nfs xfs fuse"
+MODULES_FS="ext2 ext3 ext4 btrfs reiserfs jfs nfs xfs fuse"
MODULES_USB="ehci-hcd uhci usb-ohci hid usb-storage uhci-hcd ohci-hcd usbhid sl811-hcd"
# Filesystems
-MODULES_FS="ext2 ext3 ext4 reiserfs jfs nfs xfs fuse"
+MODULES_FS="ext2 ext3 ext4 btrfs reiserfs jfs nfs xfs fuse"