/* 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.
*/
#include <stdarg.h>
#include <linux/module.h>
#include <linux/kthread.h>
#include <xen/events.h>
#include <xen/grant_table.h>
#include "common.h"
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);
struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be)
{
return be->dev;
}
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, TASK_COMM_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[TASK_COMM_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, name);
if (IS_ERR(blkif->xenblkd)) {
err = PTR_ERR(blkif->xenblkd);
blkif->xenblkd = NULL;
xenbus_dev_error(blkif->be->dev, err, "start xenblkd");
}
}
static struct xen_blkif *xen_blkif_alloc(domid_t domid)
{
struct xen_blkif *blkif;
blkif = kmem_cache_alloc(xen_blkif_cachep, GFP_KERNEL);
if (!blkif)
return ERR_PTR(-ENOMEM);
memset(blkif, 0, sizeof(*blkif));
blkif->domid = domid;
spin_lock_init(&blkif->blk_ring_lock);
atomic_set(&blkif->refcnt, 1);
init_waitqueue_head(&blkif->wq);
blkif->st_print = jiffies;
init_waitqueue_head(&blkif->waiting_to_free);
return blkif;
}
static int map_frontend_page(struct xen_blkif *blkif, unsigned long shared_page)
{
struct gnttab_map_grant_ref op;
gnttab_set_map_op(&op, (unsigned long)blkif->blk_ring_area->addr,
GNTMAP_host_map, shared_page, blkif->domid);
if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
BUG();
if (op.status) {
DPRINTK("Grant table operation failure !\n");
return op.status;
}
blkif->shmem_ref = shared_page;
blkif->shmem_handle = op.handle;
return 0;
}
static void unmap_frontend_page(struct xen_blkif *blkif)
{
struct gnttab_unmap_grant_ref op;
gnttab_set_unmap_op(&op, (unsigned long)blkif->blk_ring_area->addr,
GNTMAP_host_map, blkif->shmem_handle);
if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1))
BUG();
}
static int xen_blkif_map(struct xen_blkif *blkif, unsigned long shared_page,
unsigned int evtchn)
{
int err;
/* Already connected through? */
if (blkif->irq)
return 0;
blkif->blk_ring_area = alloc_vm_area(PAGE_SIZE);
if (!blkif->blk_ring_area)
return -ENOMEM;
err = map_frontend_page(blkif, shared_page);
if (err) {
free_vm_area(blkif->blk_ring_area);
return err;
}
switch (blkif->blk_protocol) {
case BLKIF_PROTOCOL_NATIVE:
{
struct blkif_sring *sring;
sring = (struct blkif_sring *)blkif->blk_ring_area->addr;
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_area->addr;
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_area->addr;
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) {
unmap_frontend_page(blkif);
free_vm_area(blkif->blk_ring_area);
blkif->blk_rings.common.sring = NULL;
return err;
}
blkif->irq = err;
return 0;
}
static void xen_blkif_disconnect(struct xen_blkif *blkif)
{
if (blkif->xenblkd) {
kthread_stop(blkif->xenblkd);
blkif->xenblkd = NULL;
}
atomic_dec(&blkif->refcnt);
wait_event(blkif->waiting_to_free, atomic_read(&blkif->refcnt) == 0);
atomic_inc(&blkif->refcnt);
if (blkif->irq) {
unbind_from_irqhandler(blkif->irq, blkif);
blkif->irq = 0;
}
if (blkif->blk_rings.common.sring) {
unmap_frontend_page(blkif);
free_vm_area(blkif->blk_ring_area);
blkif->blk_rings.common.sring = NULL;
}
}
void xen_blkif_free(struct xen_blkif *blkif)
{
if (!atomic_dec_and_test(&blkif->refcnt))
BUG();
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, "%d\n", be->blkif->st_oo_req);
VBD_SHOW(rd_req, "%d\n", be->blkif->st_rd_req);
VBD_SHOW(wr_req, "%d\n", be->blkif->st_wr_req);
VBD_SHOW(f_req, "%d\n", be->blkif->st_f_req);
VBD_SHOW(rd_sect, "%d\n", be->blkif->st_rd_sect);
VBD_SHOW(wr_sect, "%d\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_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);
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;
}
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)) {
DPRINTK("xen_vbd_create: device %08x could not be opened.\n",
vbd->pdevice);
return -ENOENT;
}
vbd->bdev = bdev;
if (vbd->bdev->bd_disk == NULL) {
DPRINTK("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;
DPRINTK("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);
DPRINTK("");
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;
}
if (be->blkif) {
xen_blkif_disconnect(be->blkif);
xen_vbd_free(&be->blkif->vbd);
xen_blkif_free(be->blkif);
be->blkif = NULL;
}
kfree(be);
dev_set_drvdata(&dev->dev, NULL);
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)
xenbus_dev_fatal(dev, err, "writing feature-flush-cache");
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);
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:
DPRINTK("failed");
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;
char *device_type;
DPRINTK("");
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) &&
((be->major != major) || (be->minor != minor))) {
pr_warn(DRV_PFX "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);
}
if (be->major == 0 && be->minor == 0) {
/* Front end dir is a number, which is used as the handle. */
char *p = strrchr(dev->otherend, '/') + 1;
long handle;
err = strict_strtoul(p, 0, &handle);
if (err)
return;
be->major = major;
be->minor = minor;
err = xen_vbd_create(be->blkif, handle, major, minor,
(NULL == strchr(be->mode, 'w')), cdrom);
if (err) {
be->major = 0;
be->minor = 0;
xenbus_dev_fatal(dev, err, "creating vbd structure");
return;
}
err = xenvbd_sysfs_addif(dev);
if (err) {
xen_vbd_free(&be->blkif->vbd);
be->major = 0;
be->minor = 0;
xenbus_dev_fatal(dev, err, "creating sysfs entries");
return;
}
/* 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;
DPRINTK("%s", xenbus_strstate(frontend_state));
switch (frontend_state) {
case XenbusStateInitialising:
if (dev->state == XenbusStateClosed) {
pr_info(DRV_PFX "%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 successsion 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.
*/
xen_blkif_disconnect(be->blkif);
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;
DPRINTK("%s", 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;
}
err = xen_blkbk_flush_diskcache(xbt, be, be->blkif->vbd.flush_support);
if (err)
goto abort;
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_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;
char protocol[64] = "";
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;
}
be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
err = xenbus_gather(XBT_NIL, dev->otherend, "protocol",
"%63s", protocol, NULL);
if (err)
strcpy(protocol, "unspecified, assuming native");
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;
}
pr_info(DRV_PFX "ring-ref %ld, event-channel %d, protocol %d (%s)\n",
ring_ref, evtchn, be->blkif->blk_protocol, protocol);
/* 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;
}
/* ** Driver Registration ** */
static const struct xenbus_device_id xen_blkbk_ids[] = {
{ "vbd" },
{ "" }
};
static struct xenbus_driver xen_blkbk = {
.name = "vbd",
.owner = THIS_MODULE,
.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);
}
