FUSE_DAX_SZ
loff_t dmap_end = (dmap_start + FUSE_DAX_SZ) - 1;
range->window_offset = i * FUSE_DAX_SZ;
range->length = FUSE_DAX_SZ;
map_alignment, FUSE_DAX_SZ);
inarg.len = FUSE_DAX_SZ;
#define FUSE_DAX_PAGES (FUSE_DAX_SZ / PAGE_SIZE)
loff_t end_pos = (start_pos + FUSE_DAX_SZ - 1);
dmap_end = dmap_start + FUSE_DAX_SZ - 1;