Re: [PATCH v5] ndctl: add clear error support for ndctl

["Kani, Toshimitsu" <toshi.kani@hpe.com>]

On Tue, 2017-05-02 at 13:54 -0700, Dan Williams wrote:
> On Tue, May 2, 2017 at 1:26 PM, Dave Jiang <dave.jiang@intel.com>
> wrote:
 :
> > +read sector len <
> > /sys/bus/platform/devices/nfit_test.0/$dev/$region/badblocks
> > +echo "sector: $sector len: $len"
> > +
> > +# clearing using ndctl
> > +$NDCTL clear-error -f /dev/$chardev -s $sector -l $len
> 
> Ok, so I'm glad you wrote this test it highlights one mismatched
> assumption.  The "ndctl clear-error" options should be device-
> relative "sector" offsets not region offsets. So, "ndctl clear-error
> /dev/dev0.0 -s 0" should clear device-dax instance offset 0, not
> region offset 0 A device-dax instance starts at an offset from the
> namespace, and the namespace may start anywhere within a region. So
> the clear-error command needs to translate that device-dax sector
> offset to the region offset. device-dax offset to namespace offset
> can be calculated by subtracting the device-dax instance size from
> the namespace size, the namespace offset can be calculated by
> subtracting the region resource base from the namespace resource
> base. Now, the difficulty will be that the resource values for
> nfit_test are garbage because they are vmalloc'd based, I need to
> give that some thought...

Using device-relative sector makes sense, but how does user come up
with this sector number when sysfs only provides regionN/badblocks?

Thanks,
-Toshi
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