From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Moyer Subject: Re: [PATCH v5 17/21] libnvdimm: infrastructure for btt devices Date: Wed, 17 Jun 2015 12:57:39 -0400 Message-ID: References: <20150602001134.4506.45867.stgit@dwillia2-desk3.amr.corp.intel.com> <20150602001541.4506.90125.stgit@dwillia2-desk3.amr.corp.intel.com> <20150609064200.GE9804@lst.de> <20150610184616.GL2729@linux.intel.com> <20150611072812.GB1905@lst.de> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: (Dan Williams's message of "Wed, 17 Jun 2015 09:50:33 -0700") Sender: linux-acpi-owner@vger.kernel.org To: Dan Williams Cc: Christoph Hellwig , Matthew Wilcox , Jens Axboe , Stephen Rothwell , Andrew Morton , "Rafael J. Wysocki" , Neil Brown , Greg KH , linux-nvdimm , "linux-kernel@vger.kernel.org" , Ingo Molnar , Linux ACPI , linux-api@vger.kernel.org List-Id: linux-api@vger.kernel.org Dan Williams writes: > On Wed, Jun 17, 2015 at 9:47 AM, Jeff Moyer wrote: >> Christoph Hellwig writes: >> >>> On Wed, Jun 10, 2015 at 02:46:16PM -0400, Matthew Wilcox wrote: >>>> Don't screw up rw_page. The point of rw_page is to read or write a page >>>> cache page. It can sleep, and it indicates success by using the page >>>> flags. Don't try and scqueeze rw_bytes into it. If you want rw_bytes >>>> to be a queue operation, that's one thing, but don't mess with rw_page. >>> >>> Oh, I forgot about the page manipulating nature. Yes, we'll need a different >>> operation in this case. >> >> I didn't see this addressed in the new patch set. I'm also concerned >> about the layering, but I haven't put enough time into it to really make >> a better suggestion. I really dislike the idea of yet another device >> stacking model in the kernel and I'm worried the code will go in, and the >> sysfs interface will end up as a "user abi" and we won't be able to >> change it in the future. >> >> Dan, have you made any progress on this, or do you have plans to? > > ? in v6 ->rw_bytes() moved from libnvdimm local hackery to a top-level > block device operation. Is that your concern or something else? Hmm, I guess I was conflating two things. I see now that you did move the rw_bytes into the block device operations, that looks good. I'll table my concerns over yet another stacking model until I can say something intelligent about it. Cheers, Jeff