locality of extent status tree traversal

Hi, I am running Phoronix-fio benchmark on Linux kernel 4.18.0-rc5. I observe the same nodes have been traversed on the extent status tree in "ext4_es_lookup_extent" function when ext4 write begins. What's the locality signature of ext4_es_lookup_extent? Is it possible that same logical block being looked up repeatedly (Temporal)? Is it possible that co-located logical blocks are searched by ext4_es_lookup_extent (spatial)? -- Probir Roy