Re: [PATCH] virtio-blk: Add a VIRTIO_BLK_T_OUT_FUA request type

On Wed, May 7, 2025 at 1:48 PM Alberto Faria <[email protected]> wrote:
>
> On Wed, May 7, 2025 at 8:40 PM Daniel Verkamp <[email protected]> wrote:
> > On Wed, May 7, 2025 at 8:30 AM Alberto Faria <[email protected]> wrote:
> > >
> > > This is a variant of the VIRTIO_BLK_T_OUT request type that further
> > > ensures the write becomes stable once the request completes, commonly
> > > known as a Force Unit Access (FUA) request.
> > >
> > > Also add a VIRTIO_BLK_F_OUT_FUA feature bit signaling support for this
> > > request type.
> >
> > How does this interact with the writeback field? Presumably the value
> > of writeback is ignored by FUA commands, but it would be good to make
> > that explicit.
>
> That was the intention, yes. I'll make it explicit.
>
> > Also, the device requirements "write is considered volatile when it is
> > submitted"/"write becomes stable" section seems like it should be
> > updated to include FUA requests.
>
> I added a fourth item to the list that follows those words:
>
>     +\item\label{item:flush4} the write was performed using a
> VIRTIO_BLK_T_OUT_FUA
>     +  request.
>
> That felt the cleanest to me.

Oh, sorry, I missed that this was already included in the original
patch since the context wasn't clear from the diff. This part looks
fine to me, thanks.