--- /dev/null
+/* Xenbus code for blkif backend
+ 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 as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+*/
+
+#define pr_fmt(fmt) "xen-blkback: " fmt
+
+#include <stdarg.h>
+#include <linux/module.h>
+#include <linux/kthread.h>
+#include <xen/events.h>
+#include <xen/grant_table.h>
+#include "common.h"
+
+/* Enlarge the array size in order to fully show blkback name. */
+#define BLKBACK_NAME_LEN (20)
+
+struct backend_info {
+ struct xenbus_device *dev;
+ struct xen_blkif *blkif;
+ struct xenbus_watch backend_watch;
+ unsigned major;
+ unsigned minor;
+ char *mode;
+};
+
+static struct kmem_cache *xen_blkif_cachep;
+static void connect(struct backend_info *);
+static int connect_ring(struct backend_info *);
+static void backend_changed(struct xenbus_watch *, const char **,
+ unsigned int);
+static void xen_blkif_free(struct xen_blkif *blkif);
+static void xen_vbd_free(struct xen_vbd *vbd);
+
+struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be)
+{
+ return be->dev;
+}
+
+/*
+ * The last request could free the device from softirq context and
+ * xen_blkif_free() can sleep.
+ */
+static void xen_blkif_deferred_free(struct work_struct *work)
+{
+ struct xen_blkif *blkif;
+
+ blkif = container_of(work, struct xen_blkif, free_work);
+ xen_blkif_free(blkif);
+}
+
+static int blkback_name(struct xen_blkif *blkif, char *buf)
+{
+ char *devpath, *devname;
+ struct xenbus_device *dev = blkif->be->dev;
+
+ devpath = xenbus_read(XBT_NIL, dev->nodename, "dev", NULL);
+ if (IS_ERR(devpath))
+ return PTR_ERR(devpath);
+
+ devname = strstr(devpath, "/dev/");
+ if (devname != NULL)
+ devname += strlen("/dev/");
+ else
+ devname = devpath;
+
+ snprintf(buf, BLKBACK_NAME_LEN, "blkback.%d.%s", blkif->domid, devname);
+ kfree(devpath);
+
+ return 0;
+}
+
+static void xen_update_blkif_status(struct xen_blkif *blkif)
+{
+ int err;
+ char name[BLKBACK_NAME_LEN];
+
+ /* Not ready to connect? */
+ if (!blkif->irq || !blkif->vbd.bdev)
+ 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;
+
+ err = blkback_name(blkif, name);
+ if (err) {
+ xenbus_dev_error(blkif->be->dev, err, "get blkback dev name");
+ return;
+ }
+
+ err = filemap_write_and_wait(blkif->vbd.bdev->bd_inode->i_mapping);
+ if (err) {
+ xenbus_dev_error(blkif->be->dev, err, "block flush");
+ return;
+ }
+ invalidate_inode_pages2(blkif->vbd.bdev->bd_inode->i_mapping);
+
+ blkif->xenblkd = kthread_run(xen_blkif_schedule, blkif, "%s", name);
+ if (IS_ERR(blkif->xenblkd)) {
+ err = PTR_ERR(blkif->xenblkd);
+ blkif->xenblkd = NULL;
+ xenbus_dev_error(blkif->be->dev, err, "start xenblkd");
+ return;
+ }
+}
+
+static struct xen_blkif *xen_blkif_alloc(domid_t domid)
+{
+ struct xen_blkif *blkif;
+ struct pending_req *req, *n;
+ int i, j;
+
+ BUILD_BUG_ON(MAX_INDIRECT_PAGES > BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST);
+
+ blkif = kmem_cache_zalloc(xen_blkif_cachep, GFP_KERNEL);
+ if (!blkif)
+ return ERR_PTR(-ENOMEM);
+
+ blkif->domid = domid;
+ spin_lock_init(&blkif->blk_ring_lock);
+ atomic_set(&blkif->refcnt, 1);
+ init_waitqueue_head(&blkif->wq);
+ init_completion(&blkif->drain_complete);
+ atomic_set(&blkif->drain, 0);
+ blkif->st_print = jiffies;
+ blkif->persistent_gnts.rb_node = NULL;
+ spin_lock_init(&blkif->free_pages_lock);
+ INIT_LIST_HEAD(&blkif->free_pages);
+ INIT_LIST_HEAD(&blkif->persistent_purge_list);
+ blkif->free_pages_num = 0;
+ atomic_set(&blkif->persistent_gnt_in_use, 0);
+ atomic_set(&blkif->inflight, 0);
+ INIT_WORK(&blkif->persistent_purge_work, xen_blkbk_unmap_purged_grants);
+
+ INIT_LIST_HEAD(&blkif->pending_free);
+ INIT_WORK(&blkif->free_work, xen_blkif_deferred_free);
+
+ for (i = 0; i < XEN_BLKIF_REQS; i++) {
+ req = kzalloc(sizeof(*req), GFP_KERNEL);
+ if (!req)
+ goto fail;
+ list_add_tail(&req->free_list,
+ &blkif->pending_free);
+ for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) {
+ req->segments[j] = kzalloc(sizeof(*req->segments[0]),
+ GFP_KERNEL);
+ if (!req->segments[j])
+ goto fail;
+ }
+ for (j = 0; j < MAX_INDIRECT_PAGES; j++) {
+ req->indirect_pages[j] = kzalloc(sizeof(*req->indirect_pages[0]),
+ GFP_KERNEL);
+ if (!req->indirect_pages[j])
+ goto fail;
+ }
+ }
+ spin_lock_init(&blkif->pending_free_lock);
+ init_waitqueue_head(&blkif->pending_free_wq);
+ init_waitqueue_head(&blkif->shutdown_wq);
+
+ return blkif;
+
+fail:
+ list_for_each_entry_safe(req, n, &blkif->pending_free, free_list) {
+ list_del(&req->free_list);
+ for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) {
+ if (!req->segments[j])
+ break;
+ kfree(req->segments[j]);
+ }
+ for (j = 0; j < MAX_INDIRECT_PAGES; j++) {
+ if (!req->indirect_pages[j])
+ break;
+ kfree(req->indirect_pages[j]);
+ }
+ kfree(req);
+ }
+
+ kmem_cache_free(xen_blkif_cachep, blkif);
+
+ return ERR_PTR(-ENOMEM);
+}
+
+static int xen_blkif_map(struct xen_blkif *blkif, grant_ref_t gref,
+ unsigned int evtchn)
+{
+ int err;
+
+ /* Already connected through? */
+ if (blkif->irq)
+ return 0;
+
+ err = xenbus_map_ring_valloc(blkif->be->dev, &gref, 1,
+ &blkif->blk_ring);
+ if (err < 0)
+ return err;
+
+ switch (blkif->blk_protocol) {
+ case BLKIF_PROTOCOL_NATIVE:
+ {
+ struct blkif_sring *sring;
+ sring = (struct blkif_sring *)blkif->blk_ring;
+ BACK_RING_INIT(&blkif->blk_rings.native, sring, PAGE_SIZE);
+ break;
+ }
+ case BLKIF_PROTOCOL_X86_32:
+ {
+ struct blkif_x86_32_sring *sring_x86_32;
+ sring_x86_32 = (struct blkif_x86_32_sring *)blkif->blk_ring;
+ BACK_RING_INIT(&blkif->blk_rings.x86_32, sring_x86_32, PAGE_SIZE);
+ break;
+ }
+ case BLKIF_PROTOCOL_X86_64:
+ {
+ struct blkif_x86_64_sring *sring_x86_64;
+ sring_x86_64 = (struct blkif_x86_64_sring *)blkif->blk_ring;
+ BACK_RING_INIT(&blkif->blk_rings.x86_64, sring_x86_64, PAGE_SIZE);
+ break;
+ }
+ default:
+ BUG();
+ }
+
+ err = bind_interdomain_evtchn_to_irqhandler(blkif->domid, evtchn,
+ xen_blkif_be_int, 0,
+ "blkif-backend", blkif);
+ if (err < 0) {
+ xenbus_unmap_ring_vfree(blkif->be->dev, blkif->blk_ring);
+ blkif->blk_rings.common.sring = NULL;
+ return err;
+ }
+ blkif->irq = err;
+
+ return 0;
+}
+
+static int xen_blkif_disconnect(struct xen_blkif *blkif)
+{
+ if (blkif->xenblkd) {
+ kthread_stop(blkif->xenblkd);
+ wake_up(&blkif->shutdown_wq);
+ blkif->xenblkd = NULL;
+ }
+
+ /* The above kthread_stop() guarantees that at this point we
+ * don't have any discard_io or other_io requests. So, checking
+ * for inflight IO is enough.
+ */
+ if (atomic_read(&blkif->inflight) > 0)
+ return -EBUSY;
+
+ if (blkif->irq) {
+ unbind_from_irqhandler(blkif->irq, blkif);
+ blkif->irq = 0;
+ }
+
+ if (blkif->blk_rings.common.sring) {
+ xenbus_unmap_ring_vfree(blkif->be->dev, blkif->blk_ring);
+ blkif->blk_rings.common.sring = NULL;
+ }
+
+ /* Remove all persistent grants and the cache of ballooned pages. */
+ xen_blkbk_free_caches(blkif);
+
+ return 0;
+}
+
+static void xen_blkif_free(struct xen_blkif *blkif)
+{
+ struct pending_req *req, *n;
+ int i = 0, j;
+
+ xen_blkif_disconnect(blkif);
+ xen_vbd_free(&blkif->vbd);
+
+ /* Make sure everything is drained before shutting down */
+ BUG_ON(blkif->persistent_gnt_c != 0);
+ BUG_ON(atomic_read(&blkif->persistent_gnt_in_use) != 0);
+ BUG_ON(blkif->free_pages_num != 0);
+ BUG_ON(!list_empty(&blkif->persistent_purge_list));
+ BUG_ON(!list_empty(&blkif->free_pages));
+ BUG_ON(!RB_EMPTY_ROOT(&blkif->persistent_gnts));
+
+ /* Check that there is no request in use */
+ list_for_each_entry_safe(req, n, &blkif->pending_free, free_list) {
+ list_del(&req->free_list);
+
+ for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++)
+ kfree(req->segments[j]);
+
+ for (j = 0; j < MAX_INDIRECT_PAGES; j++)
+ kfree(req->indirect_pages[j]);
+
+ kfree(req);
+ i++;
+ }
+
+ WARN_ON(i != XEN_BLKIF_REQS);
+
+ kmem_cache_free(xen_blkif_cachep, blkif);
+}
+
+int __init xen_blkif_interface_init(void)
+{
+ xen_blkif_cachep = kmem_cache_create("blkif_cache",
+ sizeof(struct xen_blkif),
+ 0, 0, NULL);
+ if (!xen_blkif_cachep)
+ return -ENOMEM;
+
+ return 0;
+}
+
+/*
+ * sysfs interface for VBD I/O requests
+ */
+
+#define VBD_SHOW(name, format, args...) \
+ static ssize_t show_##name(struct device *_dev, \
+ struct device_attribute *attr, \
+ char *buf) \
+ { \
+ struct xenbus_device *dev = to_xenbus_device(_dev); \
+ struct backend_info *be = dev_get_drvdata(&dev->dev); \
+ \
+ return sprintf(buf, format, ##args); \
+ } \
+ static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL)
+
+VBD_SHOW(oo_req, "%llu\n", be->blkif->st_oo_req);
+VBD_SHOW(rd_req, "%llu\n", be->blkif->st_rd_req);
+VBD_SHOW(wr_req, "%llu\n", be->blkif->st_wr_req);
+VBD_SHOW(f_req, "%llu\n", be->blkif->st_f_req);
+VBD_SHOW(ds_req, "%llu\n", be->blkif->st_ds_req);
+VBD_SHOW(rd_sect, "%llu\n", be->blkif->st_rd_sect);
+VBD_SHOW(wr_sect, "%llu\n", be->blkif->st_wr_sect);
+
+static struct attribute *xen_vbdstat_attrs[] = {
+ &dev_attr_oo_req.attr,
+ &dev_attr_rd_req.attr,
+ &dev_attr_wr_req.attr,
+ &dev_attr_f_req.attr,
+ &dev_attr_ds_req.attr,
+ &dev_attr_rd_sect.attr,
+ &dev_attr_wr_sect.attr,
+ NULL
+};
+
+static struct attribute_group xen_vbdstat_group = {
+ .name = "statistics",
+ .attrs = xen_vbdstat_attrs,
+};
+
+VBD_SHOW(physical_device, "%x:%x\n", be->major, be->minor);
+VBD_SHOW(mode, "%s\n", be->mode);
+
+static int xenvbd_sysfs_addif(struct xenbus_device *dev)
+{
+ int error;
+
+ error = device_create_file(&dev->dev, &dev_attr_physical_device);
+ if (error)
+ goto fail1;
+
+ error = device_create_file(&dev->dev, &dev_attr_mode);
+ if (error)
+ goto fail2;
+
+ error = sysfs_create_group(&dev->dev.kobj, &xen_vbdstat_group);
+ if (error)
+ goto fail3;
+
+ return 0;
+
+fail3: sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group);
+fail2: device_remove_file(&dev->dev, &dev_attr_mode);
+fail1: device_remove_file(&dev->dev, &dev_attr_physical_device);
+ return error;
+}
+
+static void xenvbd_sysfs_delif(struct xenbus_device *dev)
+{
+ sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group);
+ device_remove_file(&dev->dev, &dev_attr_mode);
+ device_remove_file(&dev->dev, &dev_attr_physical_device);
+}
+
+
+static void xen_vbd_free(struct xen_vbd *vbd)
+{
+ if (vbd->bdev)
+ blkdev_put(vbd->bdev, vbd->readonly ? FMODE_READ : FMODE_WRITE);
+ vbd->bdev = NULL;
+}
+
+static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle,
+ unsigned major, unsigned minor, int readonly,
+ int cdrom)
+{
+ struct xen_vbd *vbd;
+ struct block_device *bdev;
+ struct request_queue *q;
+
+ vbd = &blkif->vbd;
+ vbd->handle = handle;
+ vbd->readonly = readonly;
+ vbd->type = 0;
+
+ vbd->pdevice = MKDEV(major, minor);
+
+ bdev = blkdev_get_by_dev(vbd->pdevice, vbd->readonly ?
+ FMODE_READ : FMODE_WRITE, NULL);
+
+ if (IS_ERR(bdev)) {
+ pr_warn("xen_vbd_create: device %08x could not be opened\n",
+ vbd->pdevice);
+ return -ENOENT;
+ }
+
+ vbd->bdev = bdev;
+ if (vbd->bdev->bd_disk == NULL) {
+ pr_warn("xen_vbd_create: device %08x doesn't exist\n",
+ vbd->pdevice);
+ xen_vbd_free(vbd);
+ return -ENOENT;
+ }
+ vbd->size = vbd_sz(vbd);
+
+ if (vbd->bdev->bd_disk->flags & GENHD_FL_CD || cdrom)
+ vbd->type |= VDISK_CDROM;
+ if (vbd->bdev->bd_disk->flags & GENHD_FL_REMOVABLE)
+ vbd->type |= VDISK_REMOVABLE;
+
+ q = bdev_get_queue(bdev);
+ if (q && q->flush_flags)
+ vbd->flush_support = true;
+
+ if (q && blk_queue_secdiscard(q))
+ vbd->discard_secure = true;
+
+ pr_debug("Successful creation of handle=%04x (dom=%u)\n",
+ handle, blkif->domid);
+ return 0;
+}
+static int xen_blkbk_remove(struct xenbus_device *dev)
+{
+ struct backend_info *be = dev_get_drvdata(&dev->dev);
+
+ pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id);
+
+ if (be->major || be->minor)
+ xenvbd_sysfs_delif(dev);
+
+ if (be->backend_watch.node) {
+ unregister_xenbus_watch(&be->backend_watch);
+ kfree(be->backend_watch.node);
+ be->backend_watch.node = NULL;
+ }
+
+ dev_set_drvdata(&dev->dev, NULL);
+
+ if (be->blkif) {
+ xen_blkif_disconnect(be->blkif);
+ xen_blkif_put(be->blkif);
+ }
+
+ kfree(be->mode);
+ kfree(be);
+ return 0;
+}
+
+int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt,
+ struct backend_info *be, int state)
+{
+ struct xenbus_device *dev = be->dev;
+ int err;
+
+ err = xenbus_printf(xbt, dev->nodename, "feature-flush-cache",
+ "%d", state);
+ if (err)
+ dev_warn(&dev->dev, "writing feature-flush-cache (%d)", err);
+
+ return err;
+}
+
+static void xen_blkbk_discard(struct xenbus_transaction xbt, struct backend_info *be)
+{
+ struct xenbus_device *dev = be->dev;
+ struct xen_blkif *blkif = be->blkif;
+ int err;
+ int state = 0, discard_enable;
+ struct block_device *bdev = be->blkif->vbd.bdev;
+ struct request_queue *q = bdev_get_queue(bdev);
+
+ err = xenbus_scanf(XBT_NIL, dev->nodename, "discard-enable", "%d",
+ &discard_enable);
+ if (err == 1 && !discard_enable)
+ return;
+
+ if (blk_queue_discard(q)) {
+ err = xenbus_printf(xbt, dev->nodename,
+ "discard-granularity", "%u",
+ q->limits.discard_granularity);
+ if (err) {
+ dev_warn(&dev->dev, "writing discard-granularity (%d)", err);
+ return;
+ }
+ err = xenbus_printf(xbt, dev->nodename,
+ "discard-alignment", "%u",
+ q->limits.discard_alignment);
+ if (err) {
+ dev_warn(&dev->dev, "writing discard-alignment (%d)", err);
+ return;
+ }
+ state = 1;
+ /* Optional. */
+ err = xenbus_printf(xbt, dev->nodename,
+ "discard-secure", "%d",
+ blkif->vbd.discard_secure);
+ if (err) {
+ dev_warn(&dev->dev, "writing discard-secure (%d)", err);
+ return;
+ }
+ }
+ err = xenbus_printf(xbt, dev->nodename, "feature-discard",
+ "%d", state);
+ if (err)
+ dev_warn(&dev->dev, "writing feature-discard (%d)", err);
+}
+int xen_blkbk_barrier(struct xenbus_transaction xbt,
+ struct backend_info *be, int state)
+{
+ struct xenbus_device *dev = be->dev;
+ int err;
+
+ err = xenbus_printf(xbt, dev->nodename, "feature-barrier",
+ "%d", state);
+ if (err)
+ dev_warn(&dev->dev, "writing feature-barrier (%d)", err);
+
+ return err;
+}
+
+/*
+ * Entry point to this code when a new device is created. Allocate the basic
+ * structures, and watch the store waiting for the hotplug scripts to tell us
+ * the device's physical major and minor numbers. Switch to InitWait.
+ */
+static int xen_blkbk_probe(struct xenbus_device *dev,
+ const struct xenbus_device_id *id)
+{
+ int err;
+ struct backend_info *be = kzalloc(sizeof(struct backend_info),
+ GFP_KERNEL);
+
+ /* match the pr_debug in xen_blkbk_remove */
+ pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id);
+
+ if (!be) {
+ xenbus_dev_fatal(dev, -ENOMEM,
+ "allocating backend structure");
+ return -ENOMEM;
+ }
+ be->dev = dev;
+ dev_set_drvdata(&dev->dev, be);
+
+ be->blkif = xen_blkif_alloc(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;
+
+ err = xenbus_watch_pathfmt(dev, &be->backend_watch, backend_changed,
+ "%s/%s", dev->nodename, "physical-device");
+ if (err)
+ goto fail;
+
+ err = xenbus_switch_state(dev, XenbusStateInitWait);
+ if (err)
+ goto fail;
+
+ return 0;
+
+fail:
+ pr_warn("%s failed\n", __func__);
+ xen_blkbk_remove(dev);
+ return err;
+}
+
+
+/*
+ * Callback received when the hotplug scripts have placed the physical-device
+ * node. Read it and the mode node, and create a vbd. If the frontend is
+ * ready, connect.
+ */
+static void backend_changed(struct xenbus_watch *watch,
+ const char **vec, unsigned int len)
+{
+ int err;
+ unsigned major;
+ unsigned minor;
+ struct backend_info *be
+ = container_of(watch, struct backend_info, backend_watch);
+ struct xenbus_device *dev = be->dev;
+ int cdrom = 0;
+ unsigned long handle;
+ char *device_type;
+
+ pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id);
+
+ err = xenbus_scanf(XBT_NIL, dev->nodename, "physical-device", "%x:%x",
+ &major, &minor);
+ if (XENBUS_EXIST_ERR(err)) {
+ /*
+ * Since this watch will fire once immediately after it is
+ * registered, we expect this. Ignore it, and wait for the
+ * hotplug scripts.
+ */
+ return;
+ }
+ if (err != 2) {
+ xenbus_dev_fatal(dev, err, "reading physical-device");
+ return;
+ }
+
+ if (be->major | be->minor) {
+ if (be->major != major || be->minor != minor)
+ pr_warn("changing physical device (from %x:%x to %x:%x) not supported.\n",
+ be->major, be->minor, major, minor);
+ return;
+ }
+
+ be->mode = xenbus_read(XBT_NIL, dev->nodename, "mode", NULL);
+ if (IS_ERR(be->mode)) {
+ err = PTR_ERR(be->mode);
+ be->mode = NULL;
+ xenbus_dev_fatal(dev, err, "reading mode");
+ return;
+ }
+
+ device_type = xenbus_read(XBT_NIL, dev->otherend, "device-type", NULL);
+ if (!IS_ERR(device_type)) {
+ cdrom = strcmp(device_type, "cdrom") == 0;
+ kfree(device_type);
+ }
+
+ /* Front end dir is a number, which is used as the handle. */
+ err = kstrtoul(strrchr(dev->otherend, '/') + 1, 0, &handle);
+ if (err)
+ return;
+
+ be->major = major;
+ be->minor = minor;
+
+ err = xen_vbd_create(be->blkif, handle, major, minor,
+ !strchr(be->mode, 'w'), cdrom);
+
+ if (err)
+ xenbus_dev_fatal(dev, err, "creating vbd structure");
+ else {
+ err = xenvbd_sysfs_addif(dev);
+ if (err) {
+ xen_vbd_free(&be->blkif->vbd);
+ xenbus_dev_fatal(dev, err, "creating sysfs entries");
+ }
+ }
+
+ if (err) {
+ kfree(be->mode);
+ be->mode = NULL;
+ be->major = 0;
+ be->minor = 0;
+ } else {
+ /* We're potentially connected now */
+ xen_update_blkif_status(be->blkif);
+ }
+}
+
+
+/*
+ * Callback received when the frontend's state changes.
+ */
+static void frontend_changed(struct xenbus_device *dev,
+ enum xenbus_state frontend_state)
+{
+ struct backend_info *be = dev_get_drvdata(&dev->dev);
+ int err;
+
+ pr_debug("%s %p %s\n", __func__, dev, xenbus_strstate(frontend_state));
+
+ switch (frontend_state) {
+ case XenbusStateInitialising:
+ if (dev->state == XenbusStateClosed) {
+ pr_info("%s: prepare for reconnect\n", dev->nodename);
+ xenbus_switch_state(dev, XenbusStateInitWait);
+ }
+ break;
+
+ case XenbusStateInitialised:
+ case XenbusStateConnected:
+ /*
+ * Ensure we connect even when two watches fire in
+ * close succession and we miss the intermediate value
+ * of frontend_state.
+ */
+ if (dev->state == XenbusStateConnected)
+ break;
+
+ /*
+ * Enforce precondition before potential leak point.
+ * xen_blkif_disconnect() is idempotent.
+ */
+ err = xen_blkif_disconnect(be->blkif);
+ if (err) {
+ xenbus_dev_fatal(dev, err, "pending I/O");
+ break;
+ }
+
+ err = connect_ring(be);
+ if (err)
+ break;
+ xen_update_blkif_status(be->blkif);
+ break;
+
+ case XenbusStateClosing:
+ xenbus_switch_state(dev, XenbusStateClosing);
+ break;
+
+ case XenbusStateClosed:
+ xen_blkif_disconnect(be->blkif);
+ xenbus_switch_state(dev, XenbusStateClosed);
+ if (xenbus_dev_is_online(dev))
+ break;
+ /* fall through if not online */
+ case XenbusStateUnknown:
+ /* implies xen_blkif_disconnect() via xen_blkbk_remove() */
+ device_unregister(&dev->dev);
+ break;
+
+ default:
+ xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
+ frontend_state);
+ break;
+ }
+}
+
+
+/* ** Connection ** */
+
+
+/*
+ * Write the physical details regarding the block device to the store, and
+ * switch to Connected state.
+ */
+static void connect(struct backend_info *be)
+{
+ struct xenbus_transaction xbt;
+ int err;
+ struct xenbus_device *dev = be->dev;
+
+ pr_debug("%s %s\n", __func__, dev->otherend);
+
+ /* Supply the information about the device the frontend needs */
+again:
+ err = xenbus_transaction_start(&xbt);
+ if (err) {
+ xenbus_dev_fatal(dev, err, "starting transaction");
+ return;
+ }
+
+ /* If we can't advertise it is OK. */
+ xen_blkbk_flush_diskcache(xbt, be, be->blkif->vbd.flush_support);
+
+ xen_blkbk_discard(xbt, be);
+
+ xen_blkbk_barrier(xbt, be, be->blkif->vbd.flush_support);
+
+ err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u", 1);
+ if (err) {
+ xenbus_dev_fatal(dev, err, "writing %s/feature-persistent",
+ dev->nodename);
+ goto abort;
+ }
+ err = xenbus_printf(xbt, dev->nodename, "feature-max-indirect-segments", "%u",
+ MAX_INDIRECT_SEGMENTS);
+ if (err)
+ dev_warn(&dev->dev, "writing %s/feature-max-indirect-segments (%d)",
+ dev->nodename, err);
+
+ err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu",
+ (unsigned long long)vbd_sz(&be->blkif->vbd));
+ if (err) {
+ xenbus_dev_fatal(dev, err, "writing %s/sectors",
+ dev->nodename);
+ goto abort;
+ }
+
+ /* FIXME: use a typename instead */
+ err = xenbus_printf(xbt, dev->nodename, "info", "%u",
+ be->blkif->vbd.type |
+ (be->blkif->vbd.readonly ? VDISK_READONLY : 0));
+ if (err) {
+ xenbus_dev_fatal(dev, err, "writing %s/info",
+ dev->nodename);
+ goto abort;
+ }
+ err = xenbus_printf(xbt, dev->nodename, "sector-size", "%lu",
+ (unsigned long)
+ bdev_logical_block_size(be->blkif->vbd.bdev));
+ if (err) {
+ xenbus_dev_fatal(dev, err, "writing %s/sector-size",
+ dev->nodename);
+ goto abort;
+ }
+ err = xenbus_printf(xbt, dev->nodename, "physical-sector-size", "%u",
+ bdev_physical_block_size(be->blkif->vbd.bdev));
+ if (err)
+ xenbus_dev_error(dev, err, "writing %s/physical-sector-size",
+ dev->nodename);
+
+ err = xenbus_transaction_end(xbt, 0);
+ if (err == -EAGAIN)
+ goto again;
+ if (err)
+ xenbus_dev_fatal(dev, err, "ending transaction");
+
+ err = xenbus_switch_state(dev, XenbusStateConnected);
+ if (err)
+ xenbus_dev_fatal(dev, err, "%s: switching to Connected state",
+ dev->nodename);
+
+ return;
+ abort:
+ xenbus_transaction_end(xbt, 1);
+}
+
+
+static int connect_ring(struct backend_info *be)
+{
+ struct xenbus_device *dev = be->dev;
+ unsigned long ring_ref;
+ unsigned int evtchn;
+ unsigned int pers_grants;
+ char protocol[64] = "";
+ int err;
+
+ pr_debug("%s %s\n", __func__, 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;
+ }
+
+ be->blkif->blk_protocol = BLKIF_PROTOCOL_DEFAULT;
+ err = xenbus_gather(XBT_NIL, dev->otherend, "protocol",
+ "%63s", protocol, NULL);
+ if (err)
+ strcpy(protocol, "unspecified, assuming default");
+ else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE))
+ be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
+ else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_32))
+ be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_32;
+ else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_64))
+ be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_64;
+ else {
+ xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol);
+ return -1;
+ }
+ err = xenbus_gather(XBT_NIL, dev->otherend,
+ "feature-persistent", "%u",
+ &pers_grants, NULL);
+ if (err)
+ pers_grants = 0;
+
+ be->blkif->vbd.feature_gnt_persistent = pers_grants;
+ be->blkif->vbd.overflow_max_grants = 0;
+
+ pr_info("ring-ref %ld, event-channel %d, protocol %d (%s) %s\n",
+ ring_ref, evtchn, be->blkif->blk_protocol, protocol,
+ pers_grants ? "persistent grants" : "");
+
+ /* Map the shared frame, irq etc. */
+ err = xen_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;
+}
+
+static const struct xenbus_device_id xen_blkbk_ids[] = {
+ { "vbd" },
+ { "" }
+};
+
+static struct xenbus_driver xen_blkbk_driver = {
+ .ids = xen_blkbk_ids,
+ .probe = xen_blkbk_probe,
+ .remove = xen_blkbk_remove,
+ .otherend_changed = frontend_changed
+};
+
+int xen_blkif_xenbus_init(void)
+{
+ return xenbus_register_backend(&xen_blkbk_driver);
+}
Code Review / kvmfornfv.git / blobdiff