Help with btrfs_zero_range function

Hey Guys,
I am wondering how to convert btrfs_find_first_hole and
btrfs_fill_holes in order to support zero range for btrfs in order to
support fallocate zero range. I am pasting my code so far and please
let me known if there is something else I am missing.
The function is called btrfs_zero_range in the file I am attaching.
Regards Nick
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