qemu/hw/9pfs/virtio-9p-device.c
Greg Kurz 0e44a0fd3f virtio-9p: add reset handler
Virtio devices should implement the VirtIODevice->reset() function to
perform necessary cleanup actions and to bring the device to a quiescent
state.

In the case of the virtio-9p device, this means:
- emptying the list of active PDUs (i.e. draining all in-flight I/O)
- freeing all fids (i.e. close open file descriptors and free memory)

That's what this patch does.

The reset handler first waits for all active PDUs to complete. Since
completion happens in the QEMU global aio context, we just have to
loop around aio_poll() until the active list is empty.

The freeing part involves some actions to be performed on the backend,
like closing file descriptors or flushing extended attributes to the
underlying filesystem. The virtfs_reset() function already does the
job: it calls free_fid() for all open fids not involved in an ongoing
I/O operation. We are sure this is the case since we have drained
the PDU active list.

The current code implements all backend accesses with coroutines, but we
want to stay synchronous on the reset path. We can either change the
current code to be able to run when not in coroutine context, or create
a coroutine context and wait for virtfs_reset() to complete. This patch
goes for the latter because it results in simpler code.

Note that we also need to create a dummy PDU because it is also an API
to pass the FsContext pointer to all backend callbacks.

Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
2016-10-17 14:13:58 +02:00

233 lines
6.2 KiB
C

/*
* Virtio 9p backend
*
* Copyright IBM, Corp. 2010
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*
*/
#include "qemu/osdep.h"
#include "hw/virtio/virtio.h"
#include "qemu/sockets.h"
#include "virtio-9p.h"
#include "fsdev/qemu-fsdev.h"
#include "coth.h"
#include "hw/virtio/virtio-access.h"
#include "qemu/iov.h"
void virtio_9p_push_and_notify(V9fsPDU *pdu)
{
V9fsState *s = pdu->s;
V9fsVirtioState *v = container_of(s, V9fsVirtioState, state);
VirtQueueElement *elem = v->elems[pdu->idx];
/* push onto queue and notify */
virtqueue_push(v->vq, elem, pdu->size);
g_free(elem);
v->elems[pdu->idx] = NULL;
/* FIXME: we should batch these completions */
virtio_notify(VIRTIO_DEVICE(v), v->vq);
}
static void handle_9p_output(VirtIODevice *vdev, VirtQueue *vq)
{
V9fsVirtioState *v = (V9fsVirtioState *)vdev;
V9fsState *s = &v->state;
V9fsPDU *pdu;
ssize_t len;
VirtQueueElement *elem;
while ((pdu = pdu_alloc(s))) {
struct {
uint32_t size_le;
uint8_t id;
uint16_t tag_le;
} QEMU_PACKED out;
elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
if (!elem) {
goto out_free_pdu;
}
if (elem->in_num == 0) {
virtio_error(vdev,
"The guest sent a VirtFS request without space for "
"the reply");
goto out_free_req;
}
QEMU_BUILD_BUG_ON(sizeof(out) != 7);
v->elems[pdu->idx] = elem;
len = iov_to_buf(elem->out_sg, elem->out_num, 0,
&out, sizeof(out));
if (len != sizeof(out)) {
virtio_error(vdev, "The guest sent a malformed VirtFS request: "
"header size is %zd, should be 7", len);
goto out_free_req;
}
pdu->size = le32_to_cpu(out.size_le);
pdu->id = out.id;
pdu->tag = le16_to_cpu(out.tag_le);
qemu_co_queue_init(&pdu->complete);
pdu_submit(pdu);
}
return;
out_free_req:
virtqueue_detach_element(vq, elem, 0);
g_free(elem);
out_free_pdu:
pdu_free(pdu);
}
static uint64_t virtio_9p_get_features(VirtIODevice *vdev, uint64_t features,
Error **errp)
{
virtio_add_feature(&features, VIRTIO_9P_MOUNT_TAG);
return features;
}
static void virtio_9p_get_config(VirtIODevice *vdev, uint8_t *config)
{
int len;
struct virtio_9p_config *cfg;
V9fsVirtioState *v = VIRTIO_9P(vdev);
V9fsState *s = &v->state;
len = strlen(s->tag);
cfg = g_malloc0(sizeof(struct virtio_9p_config) + len);
virtio_stw_p(vdev, &cfg->tag_len, len);
/* We don't copy the terminating null to config space */
memcpy(cfg->tag, s->tag, len);
memcpy(config, cfg, v->config_size);
g_free(cfg);
}
static void virtio_9p_device_realize(DeviceState *dev, Error **errp)
{
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
V9fsVirtioState *v = VIRTIO_9P(dev);
V9fsState *s = &v->state;
if (v9fs_device_realize_common(s, errp)) {
goto out;
}
v->config_size = sizeof(struct virtio_9p_config) + strlen(s->fsconf.tag);
virtio_init(vdev, "virtio-9p", VIRTIO_ID_9P, v->config_size);
v->vq = virtio_add_queue(vdev, MAX_REQ, handle_9p_output);
out:
return;
}
static void virtio_9p_device_unrealize(DeviceState *dev, Error **errp)
{
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
V9fsVirtioState *v = VIRTIO_9P(dev);
V9fsState *s = &v->state;
virtio_cleanup(vdev);
v9fs_device_unrealize_common(s, errp);
}
static void virtio_9p_reset(VirtIODevice *vdev)
{
V9fsVirtioState *v = (V9fsVirtioState *)vdev;
v9fs_reset(&v->state);
}
ssize_t virtio_pdu_vmarshal(V9fsPDU *pdu, size_t offset,
const char *fmt, va_list ap)
{
V9fsState *s = pdu->s;
V9fsVirtioState *v = container_of(s, V9fsVirtioState, state);
VirtQueueElement *elem = v->elems[pdu->idx];
return v9fs_iov_vmarshal(elem->in_sg, elem->in_num, offset, 1, fmt, ap);
}
ssize_t virtio_pdu_vunmarshal(V9fsPDU *pdu, size_t offset,
const char *fmt, va_list ap)
{
V9fsState *s = pdu->s;
V9fsVirtioState *v = container_of(s, V9fsVirtioState, state);
VirtQueueElement *elem = v->elems[pdu->idx];
return v9fs_iov_vunmarshal(elem->out_sg, elem->out_num, offset, 1, fmt, ap);
}
void virtio_init_iov_from_pdu(V9fsPDU *pdu, struct iovec **piov,
unsigned int *pniov, bool is_write)
{
V9fsState *s = pdu->s;
V9fsVirtioState *v = container_of(s, V9fsVirtioState, state);
VirtQueueElement *elem = v->elems[pdu->idx];
if (is_write) {
*piov = elem->out_sg;
*pniov = elem->out_num;
} else {
*piov = elem->in_sg;
*pniov = elem->in_num;
}
}
/* virtio-9p device */
static const VMStateDescription vmstate_virtio_9p = {
.name = "virtio-9p",
.minimum_version_id = 1,
.version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_VIRTIO_DEVICE,
VMSTATE_END_OF_LIST()
},
};
static Property virtio_9p_properties[] = {
DEFINE_PROP_STRING("mount_tag", V9fsVirtioState, state.fsconf.tag),
DEFINE_PROP_STRING("fsdev", V9fsVirtioState, state.fsconf.fsdev_id),
DEFINE_PROP_END_OF_LIST(),
};
static void virtio_9p_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
dc->props = virtio_9p_properties;
dc->vmsd = &vmstate_virtio_9p;
set_bit(DEVICE_CATEGORY_STORAGE, dc->categories);
vdc->realize = virtio_9p_device_realize;
vdc->unrealize = virtio_9p_device_unrealize;
vdc->get_features = virtio_9p_get_features;
vdc->get_config = virtio_9p_get_config;
vdc->reset = virtio_9p_reset;
}
static const TypeInfo virtio_device_info = {
.name = TYPE_VIRTIO_9P,
.parent = TYPE_VIRTIO_DEVICE,
.instance_size = sizeof(V9fsVirtioState),
.class_init = virtio_9p_class_init,
};
static void virtio_9p_register_types(void)
{
type_register_static(&virtio_device_info);
}
type_init(virtio_9p_register_types)