From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Mon, 15 Oct 2018 02:27:40 -0700 From: Christoph Hellwig To: Daniel Verkamp Cc: virtualization@lists.linux-foundation.org, linux-block@vger.kernel.org, "Michael S. Tsirkin" , Jason Wang , Jens Axboe , Stefan Hajnoczi , Changpeng Liu Subject: Re: [PATCH v8] virtio_blk: add discard and write zeroes support Message-ID: <20181015092740.GA3964@infradead.org> References: <1528258740-6581-1-git-send-email-changpeng.liu@intel.com> <20181012210628.226361-1-dverkamp@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 In-Reply-To: <20181012210628.226361-1-dverkamp@chromium.org> List-ID: On Fri, Oct 12, 2018 at 02:06:28PM -0700, Daniel Verkamp wrote: > From: Changpeng Liu > > In commit 88c85538, "virtio-blk: add discard and write zeroes features > to specification" (https://github.com/oasis-tcs/virtio-spec), the virtio There is some issues in this spec. For one using the multiple ranges also for write zeroes is rather inefficient. Write zeroes really should use the same format as read and write. Second the unmap flag isn't properly specified at all, as nothing says the device may not unmap without the unmap flag. Please take a look at the SCSI or NVMe Ń•pec for some guidance. > +static inline int virtblk_setup_discard_write_zeroes(struct request *req, > + bool unmap) Why is this an inline function?