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

[John Garry]

On 14/07/2025 14:17, Christoph Hellwig wrote:
> Hi all,
> 
> I'm currently trying to sort out the nvme atomics limits mess, and
> between that, the lack of a atomic write command in nvme, and the
> overall degrading quality of cheap consumer nvme devices I'm starting
> to free really uneasy about XFS using hardware atomics by default without
> an explicit opt-in, as broken atomics implementations will lead to
> really subtle data corruption.
> 
> Is is just me, or would it be a good idea to require an explicit
> opt-in to user hardware atomics?

But isn't this just an NVMe issue? I would assume that we would look at 
such an option in the NVMe driver (to opt in when we are concerned about 
the implementation), and not the FS. SCSI is ok AFAIK.

And we also have bdev fops supporting atomic writes, so any opt in 
method needs to cover that.