From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755222AbaIKX5n (ORCPT ); Thu, 11 Sep 2014 19:57:43 -0400 Received: from mail-wg0-f44.google.com ([74.125.82.44]:43212 "EHLO mail-wg0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755134AbaIKX5k (ORCPT ); Thu, 11 Sep 2014 19:57:40 -0400 From: Arianna Avanzini To: konrad.wilk@oracle.com, boris.ostrovsky@oracle.com, david.vrabel@citrix.com, xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org Cc: hch@infradead.org, bob.liu@oracle.com, felipe.franciosi@citrix.com, axboe@fb.com, avanzini.arianna@gmail.com Subject: [PATCH RFC v2 5/5] xen, blkback: negotiate of the number of block rings with the frontend Date: Fri, 12 Sep 2014 01:57:24 +0200 Message-Id: <1410479844-2864-6-git-send-email-avanzini.arianna@gmail.com> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1410479844-2864-1-git-send-email-avanzini.arianna@gmail.com> References: <1410479844-2864-1-git-send-email-avanzini.arianna@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This commit lets the backend driver advertise the number of available hardware queues; it also implements gathering from the frontend driver the number of rings actually available for mapping. Signed-off-by: Arianna Avanzini --- drivers/block/xen-blkback/xenbus.c | 44 +++++++++++++++++++++++++++++++++++++- 1 file changed, 43 insertions(+), 1 deletion(-) diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c index a4f13cc..9ff6ced 100644 --- a/drivers/block/xen-blkback/xenbus.c +++ b/drivers/block/xen-blkback/xenbus.c @@ -477,6 +477,34 @@ static void xen_vbd_free(struct xen_vbd *vbd) vbd->bdev = NULL; } +static int xen_advertise_hw_queues(struct xen_blkif *blkif, + struct request_queue *q) +{ + struct xen_vbd *vbd = &blkif->vbd; + struct xenbus_transaction xbt; + int err; + + if (q && q->mq_ops) + vbd->nr_supported_hw_queues = q->nr_hw_queues; + + err = xenbus_transaction_start(&xbt); + if (err) { + BUG_ON(!blkif->be); + xenbus_dev_fatal(blkif->be->dev, err, "starting transaction (hw queues)"); + return err; + } + + err = xenbus_printf(xbt, blkif->be->dev->nodename, "nr_supported_hw_queues", "%u", + blkif->vbd.nr_supported_hw_queues); + if (err) + xenbus_dev_error(blkif->be->dev, err, "writing %s/nr_supported_hw_queues", + blkif->be->dev->nodename); + + xenbus_transaction_end(xbt, 0); + + return err; +} + static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle, unsigned major, unsigned minor, int readonly, int cdrom) @@ -484,6 +512,7 @@ static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle, struct xen_vbd *vbd; struct block_device *bdev; struct request_queue *q; + int err; vbd = &blkif->vbd; vbd->handle = handle; @@ -522,6 +551,10 @@ static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle, if (q && blk_queue_secdiscard(q)) vbd->discard_secure = true; + err = xen_advertise_hw_queues(blkif, q); + if (err) + return -ENOENT; + DPRINTK("Successful creation of handle=%04x (dom=%u)\n", handle, blkif->domid); return 0; @@ -935,7 +968,16 @@ static int connect_ring(struct backend_info *be) DPRINTK("%s", dev->otherend); - blkif->nr_rings = 1; + err = xenbus_gather(XBT_NIL, dev->otherend, "nr_blk_rings", + "%u", &blkif->nr_rings, NULL); + if (err) { + /* + * Frontend does not support multiqueue; force compatibility + * mode of the driver. + */ + blkif->vbd.nr_supported_hw_queues = 0; + blkif->nr_rings = 1; + } ring_ref = kzalloc(sizeof(unsigned long) * blkif->nr_rings, GFP_KERNEL); if (!ring_ref) -- 2.1.0