From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57912) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1csSun-0005fR-S0 for qemu-devel@nongnu.org; Mon, 27 Mar 2017 07:34:26 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1csSuk-0007dy-0L for qemu-devel@nongnu.org; Mon, 27 Mar 2017 07:34:25 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46152) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1csSuj-0007dS-RK for qemu-devel@nongnu.org; Mon, 27 Mar 2017 07:34:21 -0400 References: <1490690365-21109-1-git-send-email-changpeng.liu@intel.com> From: Paolo Bonzini Message-ID: <00d28fcc-446b-eff6-a5a3-6675216802b9@redhat.com> Date: Mon, 27 Mar 2017 13:34:17 +0200 MIME-Version: 1.0 In-Reply-To: <1490690365-21109-1-git-send-email-changpeng.liu@intel.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [virtio-dev] [PATCH] virtio-blk: add DISCARD support to virtio-blk driver List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Changpeng Liu , virtio-dev@lists.oasis-open.org, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, hch@lst.de Cc: qemu-devel@nongnu.org On 28/03/2017 10:39, Changpeng Liu wrote: > + if (virtio_has_feature(vdev, VIRTIO_BLK_F_DISCARD)) { > + q->limits.discard_zeroes_data = 0; Maybe you could use another feature bit to populate discard_zeroes_data. Paolo > + q->limits.discard_alignment = blk_size; > + q->limits.discard_granularity = blk_size; > + blk_queue_max_discard_sectors(q, UINT_MAX); > + blk_queue_max_discard_segments(q, 1); > + queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q); > + } > +