In the meantime, if mkfs auto-enables atomic writes (when the HW supports),I didn't say we should always "auto-enable atomic writes".
what will it do to reflink feature (in terms of enabling)?
I said if the hardware is atomic write capable, then mkfs should
always*align the filesystem* to atomic write constraints. A kernel
upgrade will eventually allow reflink and atomic writes to co-exist,
but only if the filesystem is correctly aligned to the hardware
constrains for atomic writes. We need to ensure we leave that
upgrade path open....
.... and only once we have full support can we make "mkfs
auto-enable atomic writes".