Man page 9 : bitmap_allocate_region

bitmap_allocate_region - allocate bitmap region

int bitmap_allocate_region(unsigned long *  bitmap , int  pos , int  order );

bitmap
    array of unsigned longs corresponding to the bitmap

pos
    beginning of bit region to allocate

order
    region size (log base 2 of number of bits) to allocate

Allocate (set bits in) a specified region of a bitmap.

Return 0 on success, or -EBUSY if specified region wasnAqt free (not all bits were zero).