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? From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH v8] virtio_blk: add discard and write zeroes support Date: Mon, 15 Oct 2018 02:27:40 -0700 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" Content-Transfer-Encoding: base64 Return-path: Content-Disposition: inline In-Reply-To: <20181012210628.226361-1-dverkamp@chromium.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Daniel Verkamp Cc: Jens Axboe , "Michael S. Tsirkin" , virtualization@lists.linux-foundation.org, linux-block@vger.kernel.org, Stefan Hajnoczi , Changpeng Liu List-Id: virtualization@lists.linuxfoundation.org T24gRnJpLCBPY3QgMTIsIDIwMTggYXQgMDI6MDY6MjhQTSAtMDcwMCwgRGFuaWVsIFZlcmthbXAg d3JvdGU6Cj4gRnJvbTogQ2hhbmdwZW5nIExpdSA8Y2hhbmdwZW5nLmxpdUBpbnRlbC5jb20+Cj4g Cj4gSW4gY29tbWl0IDg4Yzg1NTM4LCAidmlydGlvLWJsazogYWRkIGRpc2NhcmQgYW5kIHdyaXRl IHplcm9lcyBmZWF0dXJlcwo+IHRvIHNwZWNpZmljYXRpb24iIChodHRwczovL2dpdGh1Yi5jb20v b2FzaXMtdGNzL3ZpcnRpby1zcGVjKSwgdGhlIHZpcnRpbwoKVGhlcmUgaXMgc29tZSBpc3N1ZXMg aW4gdGhpcyBzcGVjLiAgRm9yIG9uZSB1c2luZyB0aGUgbXVsdGlwbGUgcmFuZ2VzCmFsc28gZm9y IHdyaXRlIHplcm9lcyBpcyByYXRoZXIgaW5lZmZpY2llbnQuICBXcml0ZSB6ZXJvZXMgcmVhbGx5 IHNob3VsZAp1c2UgdGhlIHNhbWUgZm9ybWF0IGFzIHJlYWQgYW5kIHdyaXRlLgoKU2Vjb25kIHRo ZSB1bm1hcCBmbGFnIGlzbid0IHByb3Blcmx5IHNwZWNpZmllZCBhdCBhbGwsIGFzIG5vdGhpbmcK c2F5cyB0aGUgZGV2aWNlIG1heSBub3QgdW5tYXAgd2l0aG91dCB0aGUgdW5tYXAgZmxhZy4gIFBs ZWFzZSB0YWtlCmEgbG9vayBhdCB0aGUgU0NTSSBvciBOVk1lINGVcGVjIGZvciBzb21lIGd1aWRh bmNlLgoKPiArc3RhdGljIGlubGluZSBpbnQgdmlydGJsa19zZXR1cF9kaXNjYXJkX3dyaXRlX3pl cm9lcyhzdHJ1Y3QgcmVxdWVzdCAqcmVxLAo+ICsJCQkJCQlib29sIHVubWFwKQoKV2h5IGlzIHRo aXMgYW4gaW5saW5lIGZ1bmN0aW9uPwpfX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fXwpWaXJ0dWFsaXphdGlvbiBtYWlsaW5nIGxpc3QKVmlydHVhbGl6YXRpb25A bGlzdHMubGludXgtZm91bmRhdGlvbi5vcmcKaHR0cHM6Ly9saXN0cy5saW51eGZvdW5kYXRpb24u b3JnL21haWxtYW4vbGlzdGluZm8vdmlydHVhbGl6YXRpb24=