RE: [PATCH v3 14/15] hw/block/nvme: Use zone metadata file for persistence

[Dmitry Fomichev]

> -----Original Message-----
> From: Klaus Jensen <its@irrelevant.dk>
> Sent: Tuesday, September 15, 2020 3:10 PM
> To: Dmitry Fomichev <Dmitry.Fomichev@wdc.com>
> Cc: Keith Busch <kbusch@kernel.org>; Klaus Jensen
> <k.jensen@samsung.com>; Kevin Wolf <kwolf@redhat.com>; Philippe
> Mathieu-Daudé <philmd@redhat.com>; Maxim Levitsky
> <mlevitsk@redhat.com>; Fam Zheng <fam@euphon.net>; Niklas Cassel
> <Niklas.Cassel@wdc.com>; Damien Le Moal <Damien.LeMoal@wdc.com>;
> qemu-block@nongnu.org; qemu-devel@nongnu.org; Alistair Francis
> <Alistair.Francis@wdc.com>; Matias Bjorling <Matias.Bjorling@wdc.com>
> Subject: Re: [PATCH v3 14/15] hw/block/nvme: Use zone metadata file for
> persistence
> 
> On Sep 14 07:14, Dmitry Fomichev wrote:
> > A ZNS drive that is emulated by this module is currently initialized
> > with all zones Empty upon startup. However, actual ZNS SSDs save the
> > state and condition of all zones in their internal NVRAM in the event
> > of power loss. When such a drive is powered up again, it closes or
> > finishes all zones that were open at the moment of shutdown. Besides
> > that, the write pointer position as well as the state and condition
> > of all zones is preserved across power-downs.
> >
> > This commit adds the capability to have a persistent zone metadata
> > to the device. The new optional module property, "zone_file",
> > is introduced. If added to the command line, this property specifies
> > the name of the file that stores the zone metadata. If "zone_file" is
> > omitted, the device will be initialized with all zones empty, the same
> > as before.
> >
> > If zone metadata is configured to be persistent, then zone descriptor
> > extensions also persist across controller shutdowns.
> >
> > Signed-off-by: Dmitry Fomichev <dmitry.fomichev@wdc.com>
> 
> This doesn't build on mingw.

Thanks for letting me know. I'll try to look into this. Do you cross-compile
with mingw64?

> 
> > ---
> >  hw/block/nvme.c | 370
> +++++++++++++++++++++++++++++++++++++++++++++---
> >  hw/block/nvme.h |  37 +++++
> >  2 files changed, 386 insertions(+), 21 deletions(-)
> >
> > diff --git a/hw/block/nvme.c b/hw/block/nvme.c
> > index b49ae83dd5..41f4c0dacd 100644
> > --- a/hw/block/nvme.c
> > +++ b/hw/block/nvme.c
> > @@ -3429,7 +3557,188 @@ static int nvme_init_zone_meta(NvmeCtrl *n,
> NvmeNamespace *ns,
> >      return 0;
> >  }
> >
> > -static void nvme_zoned_init_ctrl(NvmeCtrl *n, Error **errp)
> > +static int nvme_open_zone_file(NvmeCtrl *n, bool *init_meta)
> > +{
> > +    struct stat statbuf;
> > +    size_t fsize;
> > +    int ret;
> > +
> > +    ret = stat(n->params.zone_file, &statbuf);
> > +    if (ret && errno == ENOENT) {
> > +        *init_meta = true;
> > +    } else if (!S_ISREG(statbuf.st_mode)) {
> > +        fprintf(stderr, "%s is not a regular file\n", strerror(errno));
> > +        return -1;
> > +    }
> > +
> > +    n->zone_file_fd = open(n->params.zone_file,
> > +                           O_RDWR | O_LARGEFILE | O_BINARY | O_CREAT, 644);
> 
> mode is wrong - I think you meant for it to be octal.

Nice catch, needs to be 0644...