Do we need an opt-in for file systems use of hw atomic writes?

[Christoph Hellwig]

On Mon, Jul 14, 2025 at 09:24:07AM -0400, Theodore Ts'o wrote:
> > Is is just me, or would it be a good idea to require an explicit
> > opt-in to user hardware atomics?
> 
> How common do we think broken atomics implementations; is this
> something that we could solve using a blacklist of broken devices?

I don't know.  But cheap consumer SSDs can basically exhibit any
brokenness you can imagine.  And claiming to support atomics basically
just means filling out a single field in identify with a non-zero
value.  So my hopes of only seeing it in a few devices is low,
moreover we will only notice it was broken when people lost data.