Date: Fri, 3 Jun 2016 11:38:52 +0000 (UTC) From: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= <royger@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r301268 - head/sys/dev/xen/blkback Message-ID: <201606031138.u53Bcq9o085337@repo.freebsd.org>
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Author: royger Date: Fri Jun 3 11:38:52 2016 New Revision: 301268 URL: https://svnweb.freebsd.org/changeset/base/301268 Log: blkback: add support for hotplug scripts Hotplug scripts are needed in order to use fancy disk configurations in xl, like iSCSI disks. The job of hotplug scripts is to locally attach the disk and present it to blkback as a block device or a regular file. This change introduces a new xenstore node in the blkback hierarchy, called "physical-device-path". This is a straigh replacement for the "params" node, which was used before. Hotplug scripts will need to read the "params" node, perform whatever actions are necessary and then write the "physical-device-path" node. The hotplug script is also in charge of detaching the disk once the domain has been shutdown. Sponsored by: Citrix Systems R&D Modified: head/sys/dev/xen/blkback/blkback.c Modified: head/sys/dev/xen/blkback/blkback.c ============================================================================== --- head/sys/dev/xen/blkback/blkback.c Fri Jun 3 11:18:30 2016 (r301267) +++ head/sys/dev/xen/blkback/blkback.c Fri Jun 3 11:38:52 2016 (r301268) @@ -802,6 +802,9 @@ struct xbb_softc { /** How many times we have run out of request structures */ uint64_t request_shortages; + + /** Watch to wait for hotplug script execution */ + struct xs_watch hotplug_watch; }; /*---------------------------- Request Processing ----------------------------*/ @@ -3306,7 +3309,7 @@ xbb_connect(struct xbb_softc *xbb) { int error; - if (xenbus_get_state(xbb->dev) == XenbusStateConnected) + if (xenbus_get_state(xbb->dev) != XenbusStateInitialised) return; if (xbb_collect_frontend_info(xbb) != 0) @@ -3403,6 +3406,12 @@ xbb_shutdown(struct xbb_softc *xbb) xbb->flags |= XBBF_IN_SHUTDOWN; mtx_unlock(&xbb->lock); + if (xbb->hotplug_watch.node != NULL) { + xs_unregister_watch(&xbb->hotplug_watch); + free(xbb->hotplug_watch.node, M_XENBLOCKBACK); + xbb->hotplug_watch.node = NULL; + } + if (xenbus_get_state(xbb->dev) < XenbusStateClosing) xenbus_set_state(xbb->dev, XenbusStateClosing); @@ -3583,61 +3592,24 @@ xbb_setup_sysctl(struct xbb_softc *xbb) "communication channel pages (negotiated)"); } -/** - * Attach to a XenBus device that has been claimed by our probe routine. - * - * \param dev NewBus device object representing this Xen Block Back instance. - * - * \return 0 for success, errno codes for failure. - */ -static int -xbb_attach(device_t dev) +static void +xbb_attach_disk(struct xs_watch *watch, const char **vec, unsigned int len) { + device_t dev; struct xbb_softc *xbb; int error; - u_int max_ring_page_order; - - DPRINTF("Attaching to %s\n", xenbus_get_node(dev)); - /* - * Basic initialization. - * After this block it is safe to call xbb_detach() - * to clean up any allocated data for this instance. - */ + dev = (device_t) watch->callback_data; xbb = device_get_softc(dev); - xbb->dev = dev; - xbb->otherend_id = xenbus_get_otherend_id(dev); - TASK_INIT(&xbb->io_task, /*priority*/0, xbb_run_queue, xbb); - mtx_init(&xbb->lock, device_get_nameunit(dev), NULL, MTX_DEF); - /* - * Publish protocol capabilities for consumption by the - * front-end. - */ - error = xs_printf(XST_NIL, xenbus_get_node(xbb->dev), - "feature-barrier", "1"); - if (error) { - xbb_attach_failed(xbb, error, "writing %s/feature-barrier", - xenbus_get_node(xbb->dev)); - return (error); - } + error = xs_gather(XST_NIL, xenbus_get_node(dev), "physical-device-path", + NULL, &xbb->dev_name, NULL); + if (error != 0) + return; - error = xs_printf(XST_NIL, xenbus_get_node(xbb->dev), - "feature-flush-cache", "1"); - if (error) { - xbb_attach_failed(xbb, error, "writing %s/feature-flush-cache", - xenbus_get_node(xbb->dev)); - return (error); - } - - max_ring_page_order = flsl(XBB_MAX_RING_PAGES) - 1; - error = xs_printf(XST_NIL, xenbus_get_node(xbb->dev), - "max-ring-page-order", "%u", max_ring_page_order); - if (error) { - xbb_attach_failed(xbb, error, "writing %s/max-ring-page-order", - xenbus_get_node(xbb->dev)); - return (error); - } + xs_unregister_watch(watch); + free(watch->node, M_XENBLOCKBACK); + watch->node = NULL; /* Collect physical device information. */ error = xs_gather(XST_NIL, xenbus_get_otherend_path(xbb->dev), @@ -3648,12 +3620,11 @@ xbb_attach(device_t dev) error = xs_gather(XST_NIL, xenbus_get_node(dev), "mode", NULL, &xbb->dev_mode, - "params", NULL, &xbb->dev_name, NULL); if (error != 0) { xbb_attach_failed(xbb, error, "reading backend fields at %s", xenbus_get_node(dev)); - return (ENXIO); + return; } /* Parse fopen style mode flags. */ @@ -3664,13 +3635,11 @@ xbb_attach(device_t dev) * Verify the physical device is present and can support * the desired I/O mode. */ - DROP_GIANT(); error = xbb_open_backend(xbb); - PICKUP_GIANT(); if (error != 0) { xbb_attach_failed(xbb, error, "Unable to open %s", xbb->dev_name); - return (ENXIO); + return; } /* Use devstat(9) for recording statistics. */ @@ -3702,7 +3671,7 @@ xbb_attach(device_t dev) /*contxt*/&xbb->io_taskqueue); if (xbb->io_taskqueue == NULL) { xbb_attach_failed(xbb, error, "Unable to create taskqueue"); - return (ENOMEM); + return; } taskqueue_start_threads(&xbb->io_taskqueue, @@ -3717,10 +3686,89 @@ xbb_attach(device_t dev) if (error) { xbb_attach_failed(xbb, error, "writing %s/hotplug-status", xenbus_get_node(xbb->dev)); - return (error); + return; } /* Tell the front end that we are ready to connect. */ + xenbus_set_state(dev, XenbusStateInitialised); +} + +/** + * Attach to a XenBus device that has been claimed by our probe routine. + * + * \param dev NewBus device object representing this Xen Block Back instance. + * + * \return 0 for success, errno codes for failure. + */ +static int +xbb_attach(device_t dev) +{ + struct xbb_softc *xbb; + int error; + u_int max_ring_page_order; + struct sbuf *watch_path; + + DPRINTF("Attaching to %s\n", xenbus_get_node(dev)); + + /* + * Basic initialization. + * After this block it is safe to call xbb_detach() + * to clean up any allocated data for this instance. + */ + xbb = device_get_softc(dev); + xbb->dev = dev; + xbb->otherend_id = xenbus_get_otherend_id(dev); + TASK_INIT(&xbb->io_task, /*priority*/0, xbb_run_queue, xbb); + mtx_init(&xbb->lock, device_get_nameunit(dev), NULL, MTX_DEF); + + /* + * Publish protocol capabilities for consumption by the + * front-end. + */ + error = xs_printf(XST_NIL, xenbus_get_node(xbb->dev), + "feature-barrier", "1"); + if (error) { + xbb_attach_failed(xbb, error, "writing %s/feature-barrier", + xenbus_get_node(xbb->dev)); + return (error); + } + + error = xs_printf(XST_NIL, xenbus_get_node(xbb->dev), + "feature-flush-cache", "1"); + if (error) { + xbb_attach_failed(xbb, error, "writing %s/feature-flush-cache", + xenbus_get_node(xbb->dev)); + return (error); + } + + max_ring_page_order = flsl(XBB_MAX_RING_PAGES) - 1; + error = xs_printf(XST_NIL, xenbus_get_node(xbb->dev), + "max-ring-page-order", "%u", max_ring_page_order); + if (error) { + xbb_attach_failed(xbb, error, "writing %s/max-ring-page-order", + xenbus_get_node(xbb->dev)); + return (error); + } + + /* + * We need to wait for hotplug script execution before + * moving forward. + */ + watch_path = xs_join(xenbus_get_node(xbb->dev), "physical-device-path"); + xbb->hotplug_watch.callback_data = (uintptr_t)dev; + xbb->hotplug_watch.callback = xbb_attach_disk; + KASSERT(xbb->hotplug_watch.node == NULL, ("watch node already setup")); + xbb->hotplug_watch.node = strdup(sbuf_data(watch_path), M_XENBLOCKBACK); + sbuf_delete(watch_path); + error = xs_register_watch(&xbb->hotplug_watch); + if (error != 0) { + xbb_attach_failed(xbb, error, "failed to create watch on %s", + xbb->hotplug_watch.node); + free(xbb->hotplug_watch.node, M_XENBLOCKBACK); + return (error); + } + + /* Tell the toolstack blkback has attached. */ xenbus_set_state(dev, XenbusStateInitWait); return (0);
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