Re: [PATCH 10/23] libnvdimm/labels: Add uuid helpers

From: Dan Williams <dan.j.williams@intel.com>
To: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: linux-cxl@vger.kernel.org,
	 Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Linux NVDIMM <nvdimm@lists.linux.dev>,
	 Ben Widawsky <ben.widawsky@intel.com>,
	Vishal L Verma <vishal.l.verma@intel.com>,
	 "Schofield, Alison" <alison.schofield@intel.com>,
	"Weiny, Ira" <ira.weiny@intel.com>
Subject: Re: [PATCH 10/23] libnvdimm/labels: Add uuid helpers
Date: Thu, 12 Aug 2021 14:17:50 -0700	[thread overview]
Message-ID: <CAPcyv4iaEcQSSHN=d5Gr03w7EX+CgRnU7geQiCprao8fqtUdcA@mail.gmail.com> (raw)
In-Reply-To: <20210811191319.00006d64@Huawei.com>

On Wed, Aug 11, 2021 at 11:14 AM Jonathan Cameron
<Jonathan.Cameron@huawei.com> wrote:
>
> On Mon, 9 Aug 2021 15:28:40 -0700
> Dan Williams <dan.j.williams@intel.com> wrote:
>
> > In preparation for CXL labels that move the uuid to a different offset
> > in the label, add nsl_{ref,get,validate}_uuid(). These helpers use the
> > proper uuid_t type. That type definition predated the libnvdimm
> > subsystem, so now is as a good a time as any to convert all the uuid
> > handling in the subsystem to uuid_t to match the helpers.
> >
> > As for the whitespace changes, all new code is clang-format compliant.
> >
> > Reported-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> > Signed-off-by: Dan Williams <dan.j.williams@intel.com>
>
> There are a few interesting corners where you have cleaned out a pointless
> copy before validating uuids. Perhaps call that out as a change in here
> as it isn't as simple as just replacing like with like?
> Perhaps I'm missing some reason that was needed in the code before this
> patch.
>
> All LGTM.
>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
>
> > ---
> >  drivers/nvdimm/btt.c            |   11 +++--
> >  drivers/nvdimm/btt.h            |    4 +-
> >  drivers/nvdimm/btt_devs.c       |   12 +++---
> >  drivers/nvdimm/core.c           |   40 ++-----------------
> >  drivers/nvdimm/label.c          |   34 +++++++---------
> >  drivers/nvdimm/label.h          |    3 -
> >  drivers/nvdimm/namespace_devs.c |   83 ++++++++++++++++++++-------------------
> >  drivers/nvdimm/nd-core.h        |    5 +-
> >  drivers/nvdimm/nd.h             |   37 ++++++++++++++++-
> >  drivers/nvdimm/pfn_devs.c       |    2 -
> >  include/linux/nd.h              |    4 +-
> >  11 files changed, 115 insertions(+), 120 deletions(-)
> >
> > diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
> > index 92dec4952297..1cdfbadb7408 100644
>
> > @@ -1050,7 +1050,6 @@ static int __blk_label_update(struct nd_region *nd_region,
> >       unsigned long *free, *victim_map = NULL;
> >       struct resource *res, **old_res_list;
> >       struct nd_label_id label_id;
> > -     u8 uuid[NSLABEL_UUID_LEN];
> >       int min_dpa_idx = 0;
> >       LIST_HEAD(list);
> >       u32 nslot, slot;
> > @@ -1088,8 +1087,7 @@ static int __blk_label_update(struct nd_region *nd_region,
> >               /* mark unused labels for garbage collection */
> >               for_each_clear_bit_le(slot, free, nslot) {
> >                       nd_label = to_label(ndd, slot);
> > -                     memcpy(uuid, nd_label->uuid, NSLABEL_UUID_LEN);
> > -                     if (memcmp(uuid, nsblk->uuid, NSLABEL_UUID_LEN) != 0)
> > +                     if (!nsl_validate_uuid(ndd, nd_label, nsblk->uuid))
> >                               continue;
>
> The original code here was 'unusual'. I'm not sure why it couldn't always be
> validated in place.
>

Correct, I noticed that too and cleaned it up, but you're right I
should have at least noted that in the changelog.