On Mon, Jan 21, 2019 at 4:26 PM Wei Yang <[email protected]> wrote: [..] > >@@ -706,6 +711,22 @@ static int nd_pfn_init(struct nd_pfn *nd_pfn) > > sig = DAX_SIG; > > else > > sig = PFN_SIG; > >+ > >+ /* > >+ * Check for an existing 'pfn' superblock before writing a new > >+ * one. The intended flow is that on the first probe of an > >+ * nd_{pfn,dax} device the superblock is calculated and written > >+ * to the namespace. In this case nd_pfn_validate() returns > >+ * -ENODEV because no valid superblock exists currently. > > As you replied in following mail: > > 3/ If present, nd_pfn_validate() returns 0 and nd_dax_probe() > registers the dax0.1 device (this is a libnvdimm 'personality device). > > So at this point, nd_pfn_validate() return 0 or -ENODEV?
In this case 0, because the configuration was successfully validated. -ENODEV, is only returned for the initial case where we want the kernel to write the configuration. All other error codes are an actual failure and the probe procedure stops.
