Re: [Qemu-devel] [PATCH 2/2] block/nvme: add support for discard

[Maxim Levitsky]

On Thu, 2019-09-05 at 13:27 -0400, John Snow wrote:
> 
> On 9/5/19 9:24 AM, Maxim Levitsky wrote:
> > On Wed, 2019-08-28 at 12:03 +0300, Maxim Levitsky wrote:
> > > On Tue, 2019-08-27 at 18:29 -0400, John Snow wrote:
> > > > 
> > > > On 8/25/19 3:15 AM, Maxim Levitsky wrote:
> > > > > Signed-off-by: Maxim Levitsky <address@hidden>
> > > > > ---
> > > > >  block/nvme.c       | 83 
> > > > > ++++++++++++++++++++++++++++++++++++++++++++++
> > > > >  block/trace-events |  2 ++
> > > > >  2 files changed, 85 insertions(+)
> > > > > 
> > > > > diff --git a/block/nvme.c b/block/nvme.c
> > > > > index f8bd11e19a..dd041f39c9 100644
> > > > > --- a/block/nvme.c
> > > > > +++ b/block/nvme.c
> > > > > @@ -112,6 +112,7 @@ typedef struct {
> > > > >      bool plugged;
> > > > >  
> > > > >      bool supports_write_zeros;
> > > > > +    bool supports_discard;
> > > > >  
> > > > >      CoMutex dma_map_lock;
> > > > >      CoQueue dma_flush_queue;
> > > > > @@ -463,6 +464,7 @@ static void nvme_identify(BlockDriverState *bs, 
> > > > > int namespace, Error **errp)
> > > > >  
> > > > >      oncs = le16_to_cpu(idctrl->oncs);
> > > > >      s->supports_write_zeros = (oncs & NVME_ONCS_WRITE_ZEROS) != 0;
> > > > > +    s->supports_discard = (oncs & NVME_ONCS_DSM) != 0;
> > > > 
> > > > Same comment -- checking !!(register & FIELD) is nicer than the
> > > > negative. (I'm actually not sure even the !! is needed, but it seems to
> > > > be a QEMU-ism and I've caught myself using it...)
> > > 
> > > All right, no problem to use !!
> > > 
> > > > 
> > > > Rest looks good to me on a skim, but I'm not very well-versed in NVME.
> > > 
> > > Thanks!
> > > 
> > 
> > Kind ping about this patch series.
> > 
> > Apart from using !!, do you think that this patch series
> > can be merged, or should I do anything else?
> > Which tree do you think this should be committed to?
> > 
> > I kind of want to see that merged before the freeze
> > starts, if there are no objections,
> > to reduce the amount of pending stuff in my queue.
> > 
> 
> Didn't I ask a few other things?
> 
> like not using "res30" because you've moved the fields around, and
> trying to be consistent about "zeros" vs "zeroes".
> 
> Removing "+#define NVME_ID_NS_DLFEAT_GUARD_CRC(dlfeat)       ((dlfeat) &
> 0x10)" because it's unused.


All right I forgot about it, that's one of they joys of duplication of a kernel
driver in the userspace...


> 
> You also probably require review (or at least an ACK) from Keith Busch
> who maintains this file.
> 
> --js

All right,
        Best regards,
                Maxim Levitsky