- 根目录:
- drivers
- block
- xen-blkback
- xenbus.c
/* 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)
#define RINGREF_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;
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);
spin_lock_init(&blkif->pending_free_lock);
init_waitqueue_head(&blkif->pending_free_wq);
init_waitqueue_head(&blkif->shutdown_wq);
return blkif;
}
static int xen_blkif_map(struct xen_blkif *blkif, grant_ref_t *gref,
unsigned int nr_grefs, unsigned int evtchn)
{
int err;
/* Already connected through? */
if (blkif->irq)
return 0;
err = xenbus_map_ring_valloc(blkif->be->dev, gref, nr_grefs,
&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,
XEN_PAGE_SIZE * nr_grefs);
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,
XEN_PAGE_SIZE * nr_grefs);
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,
XEN_PAGE_SIZE * nr_grefs);
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)
{
struct pending_req *req, *n;
int i = 0, j;
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);
/* 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_PER_PAGE * blkif->nr_ring_pages));
blkif->nr_ring_pages = 0;
return 0;
}
static void xen_blkif_free(struct xen_blkif *blkif)
{
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));
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_printf(XBT_NIL, dev->nodename, "max-ring-page-order", "%u",
xen_blkif_max_ring_order);
if (err)
pr_warn("%s write out 'max-ring-page-order' failed\n", __func__);
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 int ring_ref[XENBUS_MAX_RING_GRANTS];
unsigned int evtchn, nr_grefs, ring_page_order;
unsigned int pers_grants;
char protocol[64] = "";
struct pending_req *req, *n;
int err, i, j;
pr_debug("%s %s\n", __func__, dev->otherend);
err = xenbus_scanf(XBT_NIL, dev->otherend, "event-channel", "%u",
&evtchn);
if (err != 1) {
err = -EINVAL;
xenbus_dev_fatal(dev, err, "reading %s/event-channel",
dev->otherend);
return err;
}
pr_info("event-channel %u\n", evtchn);
err = xenbus_scanf(XBT_NIL, dev->otherend, "ring-page-order", "%u",
&ring_page_order);
if (err != 1) {
err = xenbus_scanf(XBT_NIL, dev->otherend, "ring-ref",
"%u", &ring_ref[0]);
if (err != 1) {
err = -EINVAL;
xenbus_dev_fatal(dev, err, "reading %s/ring-ref",
dev->otherend);
return err;
}
nr_grefs = 1;
pr_info("%s:using single page: ring-ref %d\n", dev->otherend,
ring_ref[0]);
} else {
unsigned int i;
if (ring_page_order > xen_blkif_max_ring_order) {
err = -EINVAL;
xenbus_dev_fatal(dev, err, "%s/request %d ring page order exceed max:%d",
dev->otherend, ring_page_order,
xen_blkif_max_ring_order);
return err;
}
nr_grefs = 1 << ring_page_order;
for (i = 0; i < nr_grefs; i++) {
char ring_ref_name[RINGREF_NAME_LEN];
snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
err = xenbus_scanf(XBT_NIL, dev->otherend, ring_ref_name,
"%u", &ring_ref[i]);
if (err != 1) {
err = -EINVAL;
xenbus_dev_fatal(dev, err, "reading %s/%s",
dev->otherend, ring_ref_name);
return err;
}
pr_info("ring-ref%u: %u\n", i, ring_ref[i]);
}
}
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;
be->blkif->nr_ring_pages = nr_grefs;
pr_info("ring-pages:%d, event-channel %d, protocol %d (%s) %s\n",
nr_grefs, evtchn, be->blkif->blk_protocol, protocol,
pers_grants ? "persistent grants" : "");
for (i = 0; i < nr_grefs * XEN_BLKIF_REQS_PER_PAGE; i++) {
req = kzalloc(sizeof(*req), GFP_KERNEL);
if (!req)
goto fail;
list_add_tail(&req->free_list, &be->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;
}
}
/* Map the shared frame, irq etc. */
err = xen_blkif_map(be->blkif, ring_ref, nr_grefs, evtchn);
if (err) {
xenbus_dev_fatal(dev, err, "mapping ring-ref port %u", evtchn);
return err;
}
return 0;
fail:
list_for_each_entry_safe(req, n, &be->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);
}
return -ENOMEM;
}
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);
}