--- /dev/null
+/* drivers/xen/blktap/xenbus.c
+ *
+ * Xenbus code for blktap
+ *
+ * Copyright (c) 2004-2005, Andrew Warfield and Julian Chesterfield
+ *
+ * Based on the blkback xenbus code:
+ *
+ * Copyright (C) 2005 Rusty Russell <rusty@rustcorp.com.au>
+ * Copyright (C) 2005 XenSource Ltd
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include <stdarg.h>
+#include <linux/module.h>
+#include <linux/kthread.h>
+#include <xen/xenbus.h>
+#include "common.h"
+
+
+struct backend_info
+{
+ struct xenbus_device *dev;
+ blkif_t *blkif;
+ struct xenbus_watch backend_watch;
+ int xenbus_id;
+};
+
+
+static void connect(struct backend_info *);
+static int connect_ring(struct backend_info *);
+static int blktap_remove(struct xenbus_device *dev);
+static int blktap_probe(struct xenbus_device *dev,
+ const struct xenbus_device_id *id);
+static void tap_backend_changed(struct xenbus_watch *, const char **,
+ unsigned int);
+static void tap_frontend_changed(struct xenbus_device *dev,
+ enum xenbus_state frontend_state);
+
+static int strsep_len(const char *str, char c, unsigned int len)
+{
+ unsigned int i;
+
+ for (i = 0; str[i]; i++)
+ if (str[i] == c) {
+ if (len == 0)
+ return i;
+ len--;
+ }
+ return (len == 0) ? i : -ERANGE;
+}
+
+static long get_id(const char *str)
+{
+ int len,end;
+ const char *ptr;
+ char *tptr, num[10];
+
+ len = strsep_len(str, '/', 2);
+ end = strlen(str);
+ if ( (len < 0) || (end < 0) ) return -1;
+
+ ptr = str + len + 1;
+ strncpy(num,ptr,end - len);
+ tptr = num + (end - (len + 1));
+ *tptr = '\0';
+ DPRINTK("Get_id called for %s (%s)\n",str,num);
+
+ return simple_strtol(num, NULL, 10);
+}
+
+static void tap_update_blkif_status(blkif_t *blkif)
+{
+ int err;
+
+ /* Not ready to connect? */
+ if(!blkif->irq || !blkif->sectors) {
+ return;
+ }
+
+ /* Already connected? */
+ if (blkif->be->dev->state == XenbusStateConnected)
+ return;
+
+ /* Attempt to connect: exit if we fail to. */
+ connect(blkif->be);
+ if (blkif->be->dev->state != XenbusStateConnected)
+ return;
+
+ blkif->xenblkd = kthread_run(tap_blkif_schedule, blkif,
+ "xvd %d",
+ blkif->domid);
+
+ if (IS_ERR(blkif->xenblkd)) {
+ err = PTR_ERR(blkif->xenblkd);
+ blkif->xenblkd = NULL;
+ xenbus_dev_fatal(blkif->be->dev, err, "start xenblkd");
+ WPRINTK("Error starting thread\n");
+ }
+}
+
+static int blktap_remove(struct xenbus_device *dev)
+{
+ struct backend_info *be = dev->dev.driver_data;
+
+ if (be->backend_watch.node) {
+ unregister_xenbus_watch(&be->backend_watch);
+ kfree(be->backend_watch.node);
+ be->backend_watch.node = NULL;
+ }
+ if (be->blkif) {
+ if (be->blkif->xenblkd)
+ kthread_stop(be->blkif->xenblkd);
+ signal_tapdisk(be->blkif->dev_num);
+ tap_blkif_free(be->blkif);
+ be->blkif = NULL;
+ }
+ kfree(be);
+ dev->dev.driver_data = NULL;
+ return 0;
+}
+
+/**
+ * Entry point to this code when a new device is created. Allocate
+ * the basic structures, and watch the store waiting for the
+ * user-space program to tell us the physical device info. Switch to
+ * InitWait.
+ */
+static int blktap_probe(struct xenbus_device *dev,
+ const struct xenbus_device_id *id)
+{
+ int err;
+ struct backend_info *be = kzalloc(sizeof(struct backend_info),
+ GFP_KERNEL);
+ if (!be) {
+ xenbus_dev_fatal(dev, -ENOMEM,
+ "allocating backend structure");
+ return -ENOMEM;
+ }
+
+ be->dev = dev;
+ dev->dev.driver_data = be;
+ be->xenbus_id = get_id(dev->nodename);
+
+ be->blkif = tap_alloc_blkif(dev->otherend_id);
+ if (IS_ERR(be->blkif)) {
+ err = PTR_ERR(be->blkif);
+ be->blkif = NULL;
+ xenbus_dev_fatal(dev, err, "creating block interface");
+ goto fail;
+ }
+
+ /* setup back pointer */
+ be->blkif->be = be;
+ be->blkif->sectors = 0;
+
+ /* set a watch on disk info, waiting for userspace to update details*/
+ err = xenbus_watch_path2(dev, dev->nodename, "info",
+ &be->backend_watch, tap_backend_changed);
+ if (err)
+ goto fail;
+
+ err = xenbus_switch_state(dev, XenbusStateInitWait);
+ if (err)
+ goto fail;
+ return 0;
+
+fail:
+ DPRINTK("blktap probe failed");
+ blktap_remove(dev);
+ return err;
+}
+
+
+/**
+ * Callback received when the user space code has placed the device
+ * information in xenstore.
+ */
+static void tap_backend_changed(struct xenbus_watch *watch,
+ const char **vec, unsigned int len)
+{
+ int err;
+ unsigned long info;
+ struct backend_info *be
+ = container_of(watch, struct backend_info, backend_watch);
+ struct xenbus_device *dev = be->dev;
+
+ /**
+ * Check to see whether userspace code has opened the image
+ * and written sector
+ * and disk info to xenstore
+ */
+ err = xenbus_gather(XBT_NIL, dev->nodename, "info", "%lu", &info,
+ NULL);
+ if (err) {
+ xenbus_dev_error(dev, err, "getting info");
+ return;
+ }
+
+ DPRINTK("Userspace update on disk info, %lu\n",info);
+
+ err = xenbus_gather(XBT_NIL, dev->nodename, "sectors", "%llu",
+ &be->blkif->sectors, NULL);
+
+ /* Associate tap dev with domid*/
+ be->blkif->dev_num = dom_to_devid(be->blkif->domid, be->xenbus_id,
+ be->blkif);
+ DPRINTK("Thread started for domid [%d], connecting disk\n",
+ be->blkif->dev_num);
+
+ tap_update_blkif_status(be->blkif);
+}
+
+/**
+ * Callback received when the frontend's state changes.
+ */
+static void tap_frontend_changed(struct xenbus_device *dev,
+ enum xenbus_state frontend_state)
+{
+ struct backend_info *be = dev->dev.driver_data;
+ int err;
+
+ DPRINTK("");
+
+ switch (frontend_state) {
+ case XenbusStateInitialising:
+ break;
+
+ case XenbusStateInitialised:
+ case XenbusStateConnected:
+ /* Ensure we connect even when two watches fire in
+ close successsion and we miss the intermediate value
+ of frontend_state. */
+ if (dev->state == XenbusStateConnected)
+ break;
+
+ err = connect_ring(be);
+ if (err)
+ break;
+ tap_update_blkif_status(be->blkif);
+ break;
+
+ case XenbusStateClosing:
+ xenbus_switch_state(dev, XenbusStateClosing);
+ break;
+
+ case XenbusStateClosed:
+ device_unregister(&dev->dev);
+ break;
+
+ case XenbusStateUnknown:
+ case XenbusStateInitWait:
+ default:
+ xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
+ frontend_state);
+ break;
+ }
+}
+
+
+/**
+ * Switch to Connected state.
+ */
+static void connect(struct backend_info *be)
+{
+ int err;
+
+ struct xenbus_device *dev = be->dev;
+
+ err = xenbus_switch_state(dev, XenbusStateConnected);
+ if (err)
+ xenbus_dev_fatal(dev, err, "switching to Connected state",
+ dev->nodename);
+
+ return;
+}
+
+
+static int connect_ring(struct backend_info *be)
+{
+ struct xenbus_device *dev = be->dev;
+ unsigned long ring_ref;
+ unsigned int evtchn;
+ int err;
+
+ DPRINTK("%s", dev->otherend);
+
+ err = xenbus_gather(XBT_NIL, dev->otherend, "ring-ref", "%lu",
+ &ring_ref, "event-channel", "%u", &evtchn, NULL);
+ if (err) {
+ xenbus_dev_fatal(dev, err,
+ "reading %s/ring-ref and event-channel",
+ dev->otherend);
+ return err;
+ }
+
+ /* Map the shared frame, irq etc. */
+ err = tap_blkif_map(be->blkif, ring_ref, evtchn);
+ if (err) {
+ xenbus_dev_fatal(dev, err, "mapping ring-ref %lu port %u",
+ ring_ref, evtchn);
+ return err;
+ }
+
+ return 0;
+}
+
+
+/* ** Driver Registration ** */
+
+
+static struct xenbus_device_id blktap_ids[] = {
+ { "tap" },
+ { "" }
+};
+
+
+static struct xenbus_driver blktap = {
+ .name = "tap",
+ .owner = THIS_MODULE,
+ .ids = blktap_ids,
+ .probe = blktap_probe,
+ .remove = blktap_remove,
+ .otherend_changed = tap_frontend_changed
+};
+
+
+void tap_blkif_xenbus_init(void)
+{
+ xenbus_register_backend(&blktap);
+}
git://git.onelab.eu / linux-2.6.git / blobdiff