Update parts of struct btrfs_delayed_ref_head and updated where used,
add more prototypes. More still needs to be synced.
Signed-off-by: David Sterba <dsterba@suse.com>
Add the GPL v2 header to files where it was missing and is not from an
external source, update to the most recent version with the address.
Signed-off-by: David Sterba <dsterba@suse.com>