Commit 71ebd719 authored by Stefano Stabellini's avatar Stefano Stabellini Committed by Juergen Gross

xen/9pfs: connect to the backend

Implement functions to handle the xenbus handshake. Upon connection,
allocate the rings according to the protocol specification.

Initialize a work_struct and a wait_queue. The work_struct will be used
to schedule work upon receiving an event channel notification from the
backend. The wait_queue will be used to wait when the ring is full and
we need to send a new request.

CC: groug@kaod.org
CC: boris.ostrovsky@oracle.com
CC: jgross@suse.com
CC: Eric Van Hensbergen <ericvh@gmail.com>
CC: Ron Minnich <rminnich@sandia.gov>
CC: Latchesar Ionkov <lucho@ionkov.net>
CC: v9fs-developer@lists.sourceforge.net
Signed-off-by: default avatarStefano Stabellini <stefano@aporeto.com>
Reviewed-by: default avatarJuergen Gross <jgross@suse.com>
Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
parent 868eb122
......@@ -37,10 +37,54 @@
#include <xen/interface/io/9pfs.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/rwlock.h>
#include <net/9p/9p.h>
#include <net/9p/client.h>
#include <net/9p/transport.h>
#define XEN_9PFS_NUM_RINGS 2
#define XEN_9PFS_RING_ORDER 6
#define XEN_9PFS_RING_SIZE XEN_FLEX_RING_SIZE(XEN_9PFS_RING_ORDER)
struct xen_9pfs_header {
uint32_t size;
uint8_t id;
uint16_t tag;
/* uint8_t sdata[]; */
} __attribute__((packed));
/* One per ring, more than one per 9pfs share */
struct xen_9pfs_dataring {
struct xen_9pfs_front_priv *priv;
struct xen_9pfs_data_intf *intf;
grant_ref_t ref;
int evtchn;
int irq;
/* protect a ring from concurrent accesses */
spinlock_t lock;
struct xen_9pfs_data data;
wait_queue_head_t wq;
struct work_struct work;
};
/* One per 9pfs share */
struct xen_9pfs_front_priv {
struct list_head list;
struct xenbus_device *dev;
char *tag;
struct p9_client *client;
int num_rings;
struct xen_9pfs_dataring *rings;
};
static LIST_HEAD(xen_9pfs_devs);
static DEFINE_RWLOCK(xen_9pfs_lock);
static int p9_xen_cancel(struct p9_client *client, struct p9_req_t *req)
{
return 0;
......@@ -60,6 +104,25 @@ static int p9_xen_request(struct p9_client *client, struct p9_req_t *p9_req)
return 0;
}
static void p9_xen_response(struct work_struct *work)
{
}
static irqreturn_t xen_9pfs_front_event_handler(int irq, void *r)
{
struct xen_9pfs_dataring *ring = r;
if (!ring || !ring->priv->client) {
/* ignore spurious interrupt */
return IRQ_HANDLED;
}
wake_up_interruptible(&ring->wq);
schedule_work(&ring->work);
return IRQ_HANDLED;
}
static struct p9_trans_module p9_xen_trans = {
.name = "xen",
.maxsize = 1 << (XEN_9PFS_RING_ORDER + XEN_PAGE_SHIFT),
......@@ -76,25 +139,243 @@ static const struct xenbus_device_id xen_9pfs_front_ids[] = {
{ "" }
};
static void xen_9pfs_front_free(struct xen_9pfs_front_priv *priv)
{
int i, j;
write_lock(&xen_9pfs_lock);
list_del(&priv->list);
write_unlock(&xen_9pfs_lock);
for (i = 0; i < priv->num_rings; i++) {
if (!priv->rings[i].intf)
break;
if (priv->rings[i].irq > 0)
unbind_from_irqhandler(priv->rings[i].irq, priv->dev);
if (priv->rings[i].data.in) {
for (j = 0; j < (1 << XEN_9PFS_RING_ORDER); j++) {
grant_ref_t ref;
ref = priv->rings[i].intf->ref[j];
gnttab_end_foreign_access(ref, 0, 0);
}
free_pages((unsigned long)priv->rings[i].data.in,
XEN_9PFS_RING_ORDER -
(PAGE_SHIFT - XEN_PAGE_SHIFT));
}
gnttab_end_foreign_access(priv->rings[i].ref, 0, 0);
free_page((unsigned long)priv->rings[i].intf);
}
kfree(priv->rings);
kfree(priv->tag);
kfree(priv);
}
static int xen_9pfs_front_remove(struct xenbus_device *dev)
{
struct xen_9pfs_front_priv *priv = dev_get_drvdata(&dev->dev);
dev_set_drvdata(&dev->dev, NULL);
xen_9pfs_front_free(priv);
return 0;
}
static int xen_9pfs_front_alloc_dataring(struct xenbus_device *dev,
struct xen_9pfs_dataring *ring)
{
int i = 0;
int ret = -ENOMEM;
void *bytes = NULL;
init_waitqueue_head(&ring->wq);
spin_lock_init(&ring->lock);
INIT_WORK(&ring->work, p9_xen_response);
ring->intf = (struct xen_9pfs_data_intf *)get_zeroed_page(GFP_KERNEL);
if (!ring->intf)
return ret;
ret = gnttab_grant_foreign_access(dev->otherend_id,
virt_to_gfn(ring->intf), 0);
if (ret < 0)
goto out;
ring->ref = ret;
bytes = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
XEN_9PFS_RING_ORDER - (PAGE_SHIFT - XEN_PAGE_SHIFT));
if (!bytes) {
ret = -ENOMEM;
goto out;
}
for (; i < (1 << XEN_9PFS_RING_ORDER); i++) {
ret = gnttab_grant_foreign_access(
dev->otherend_id, virt_to_gfn(bytes) + i, 0);
if (ret < 0)
goto out;
ring->intf->ref[i] = ret;
}
ring->intf->ring_order = XEN_9PFS_RING_ORDER;
ring->data.in = bytes;
ring->data.out = bytes + XEN_9PFS_RING_SIZE;
ret = xenbus_alloc_evtchn(dev, &ring->evtchn);
if (ret)
goto out;
ring->irq = bind_evtchn_to_irqhandler(ring->evtchn,
xen_9pfs_front_event_handler,
0, "xen_9pfs-frontend", ring);
if (ring->irq >= 0)
return 0;
xenbus_free_evtchn(dev, ring->evtchn);
ret = ring->irq;
out:
if (bytes) {
for (i--; i >= 0; i--)
gnttab_end_foreign_access(ring->intf->ref[i], 0, 0);
free_pages((unsigned long)bytes,
XEN_9PFS_RING_ORDER -
(PAGE_SHIFT - XEN_PAGE_SHIFT));
}
gnttab_end_foreign_access(ring->ref, 0, 0);
free_page((unsigned long)ring->intf);
return ret;
}
static int xen_9pfs_front_probe(struct xenbus_device *dev,
const struct xenbus_device_id *id)
{
int ret, i;
struct xenbus_transaction xbt;
struct xen_9pfs_front_priv *priv = NULL;
char *versions;
unsigned int max_rings, max_ring_order, len;
versions = xenbus_read(XBT_NIL, dev->otherend, "versions", &len);
if (!len)
return -EINVAL;
if (strcmp(versions, "1")) {
kfree(versions);
return -EINVAL;
}
kfree(versions);
max_rings = xenbus_read_unsigned(dev->otherend, "max-rings", 0);
if (max_rings < XEN_9PFS_NUM_RINGS)
return -EINVAL;
max_ring_order = xenbus_read_unsigned(dev->otherend,
"max-ring-page-order", 0);
if (max_ring_order < XEN_9PFS_RING_ORDER)
return -EINVAL;
priv = kzalloc(sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
priv->dev = dev;
priv->num_rings = XEN_9PFS_NUM_RINGS;
priv->rings = kcalloc(priv->num_rings, sizeof(*priv->rings),
GFP_KERNEL);
if (!priv->rings) {
kfree(priv);
return -ENOMEM;
}
for (i = 0; i < priv->num_rings; i++) {
priv->rings[i].priv = priv;
ret = xen_9pfs_front_alloc_dataring(dev, &priv->rings[i]);
if (ret < 0)
goto error;
}
again:
ret = xenbus_transaction_start(&xbt);
if (ret) {
xenbus_dev_fatal(dev, ret, "starting transaction");
goto error;
}
ret = xenbus_printf(xbt, dev->nodename, "version", "%u", 1);
if (ret)
goto error_xenbus;
ret = xenbus_printf(xbt, dev->nodename, "num-rings", "%u",
priv->num_rings);
if (ret)
goto error_xenbus;
for (i = 0; i < priv->num_rings; i++) {
char str[16];
BUILD_BUG_ON(XEN_9PFS_NUM_RINGS > 9);
sprintf(str, "ring-ref%u", i);
ret = xenbus_printf(xbt, dev->nodename, str, "%d",
priv->rings[i].ref);
if (ret)
goto error_xenbus;
sprintf(str, "event-channel-%u", i);
ret = xenbus_printf(xbt, dev->nodename, str, "%u",
priv->rings[i].evtchn);
if (ret)
goto error_xenbus;
}
priv->tag = xenbus_read(xbt, dev->nodename, "tag", NULL);
if (!priv->tag) {
ret = -EINVAL;
goto error_xenbus;
}
ret = xenbus_transaction_end(xbt, 0);
if (ret) {
if (ret == -EAGAIN)
goto again;
xenbus_dev_fatal(dev, ret, "completing transaction");
goto error;
}
write_lock(&xen_9pfs_lock);
list_add_tail(&priv->list, &xen_9pfs_devs);
write_unlock(&xen_9pfs_lock);
dev_set_drvdata(&dev->dev, priv);
xenbus_switch_state(dev, XenbusStateInitialised);
return 0;
error_xenbus:
xenbus_transaction_end(xbt, 1);
xenbus_dev_fatal(dev, ret, "writing xenstore");
error:
dev_set_drvdata(&dev->dev, NULL);
xen_9pfs_front_free(priv);
return ret;
}
static int xen_9pfs_front_resume(struct xenbus_device *dev)
{
dev_warn(&dev->dev, "suspsend/resume unsupported\n");
return 0;
}
static void xen_9pfs_front_changed(struct xenbus_device *dev,
enum xenbus_state backend_state)
{
switch (backend_state) {
case XenbusStateReconfiguring:
case XenbusStateReconfigured:
case XenbusStateInitialising:
case XenbusStateInitialised:
case XenbusStateUnknown:
break;
case XenbusStateInitWait:
break;
case XenbusStateConnected:
xenbus_switch_state(dev, XenbusStateConnected);
break;
case XenbusStateClosed:
if (dev->state == XenbusStateClosed)
break;
/* Missed the backend's CLOSING state -- fallthrough */
case XenbusStateClosing:
xenbus_frontend_closed(dev);
break;
}
}
static struct xenbus_driver xen_9pfs_front_driver = {
......
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