From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Tue, 22 Jan 2019 08:46:47 +0800 From: Wei Yang Subject: Re: [PATCH] libnvdimm: Clarify nd_pfn_init() flow Message-ID: <20190122004647.GA6575@richard> Reply-To: Wei Yang References: <154785884329.2202034.3295476681016958230.stgit@dwillia2-desk3.amr.corp.intel.com> <20190122002615.GB5855@richard> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Dan Williams Cc: Wei Yang , linux-nvdimm , Linux Kernel Mailing List List-ID: On Mon, Jan 21, 2019 at 04:29:08PM -0800, Dan Williams wrote: >On Mon, Jan 21, 2019 at 4:26 PM Wei Yang 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. To be honest, this maybe crystal clear for you. But I still feel a little confused. Especially on differentiating those cases. How many cases we have? And what's your first probe mean? This the nd_btt/pfn/dax_probe()? or the linux driver probe? -- Wei Yang Help you, Help me