Re: [PATCH 01/21] block: Add atomic write operations to request_queue limits

Bart Van Assche <bvanassche@xxxxxxx> · Wed, 4 Oct 2023 14:00:58 -0700

On 10/3/23 20:00, Martin K. Petersen wrote:

Bart,

   also that there are no guarantees that the data written by an atomic
   write will survive a power failure. See also the difference between
   the NVMe parameters AWUN and AWUPF.

We only care about *PF. The *N variants were cut from the same cloth as
TRIM and UNMAP.

Hi Martin,

Has the following approach been considered? RWF_ATOMIC only guarantees 
atomicity. Persistence is not guaranteed without fsync() / fdatasync().

I think this would be more friendly towards battery-powered devices
(smartphones). On these devices it can be safe to skip fsync() / 
fdatasync() if the battery level is high enough.

Thanks,

Bart.