| Message ID | 147575953018.4745.3158241454234330045.stgit@bahia (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Oct 06, 2016 at 03:12:10PM +0200, Greg Kurz wrote: > 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> > --- > hw/9pfs/9p.c | 31 +++++++++++++++++++++++++++++++ > hw/9pfs/9p.h | 1 + > hw/9pfs/virtio-9p-device.c | 8 ++++++++ > 3 files changed, 40 insertions(+) > > diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c > index 119ee584969b..42137395037e 100644 > --- a/hw/9pfs/9p.c > +++ b/hw/9pfs/9p.c > @@ -3522,6 +3522,37 @@ void v9fs_device_unrealize_common(V9fsState *s, Error **errp) > g_free(s->tag); > } > > + > +typedef struct VirtfsCoResetData { > + V9fsPDU pdu; > + bool done; > +} VirtfsCoResetData; > + > +static void coroutine_fn virtfs_co_reset(void *opaque) > +{ > + VirtfsCoResetData *data = opaque; > + > + virtfs_reset(&data->pdu); > + data->done = true; > +} > + > +void v9fs_reset(V9fsState *s) > +{ > + VirtfsCoResetData data = { .pdu = { .s = s }, .done = false }; > + Coroutine *co; > + > + while (!QLIST_EMPTY(&s->active_list)) { > + aio_poll(qemu_get_aio_context(), true); > + } > + > + co = qemu_coroutine_create(virtfs_co_reset, &data); > + qemu_coroutine_enter(co); > + > + while (!data.done) { > + aio_poll(qemu_get_aio_context(), true); > + } > +} > + > static void __attribute__((__constructor__)) v9fs_set_fd_limit(void) > { > struct rlimit rlim; > diff --git a/hw/9pfs/9p.h b/hw/9pfs/9p.h > index d539d2ebe9c0..6b69eaf24614 100644 > --- a/hw/9pfs/9p.h > +++ b/hw/9pfs/9p.h > @@ -339,5 +339,6 @@ ssize_t pdu_unmarshal(V9fsPDU *pdu, size_t offset, const char *fmt, ...); > V9fsPDU *pdu_alloc(V9fsState *s); > void pdu_free(V9fsPDU *pdu); > void pdu_submit(V9fsPDU *pdu); > +void v9fs_reset(V9fsState *s); > > #endif > diff --git a/hw/9pfs/virtio-9p-device.c b/hw/9pfs/virtio-9p-device.c > index 009b43f6d045..b73d72aceb64 100644 > --- a/hw/9pfs/virtio-9p-device.c > +++ b/hw/9pfs/virtio-9p-device.c > @@ -130,6 +130,13 @@ static void virtio_9p_device_unrealize(DeviceState *dev, Error **errp) > 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) > { > @@ -188,6 +195,7 @@ static void virtio_9p_class_init(ObjectClass *klass, void *data) > 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 = {
On Thu, 6 Oct 2016 19:11:03 +0300 "Michael S. Tsirkin" <mst@redhat.com> wrote: > On Thu, Oct 06, 2016 at 03:12:10PM +0200, Greg Kurz wrote: > > 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> > Unless someone objects, this will go through my tree. > > --- > > hw/9pfs/9p.c | 31 +++++++++++++++++++++++++++++++ > > hw/9pfs/9p.h | 1 + > > hw/9pfs/virtio-9p-device.c | 8 ++++++++ > > 3 files changed, 40 insertions(+) > > > > diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c > > index 119ee584969b..42137395037e 100644 > > --- a/hw/9pfs/9p.c > > +++ b/hw/9pfs/9p.c > > @@ -3522,6 +3522,37 @@ void v9fs_device_unrealize_common(V9fsState *s, Error **errp) > > g_free(s->tag); > > } > > > > + And I'll remove the empty line :) > > +typedef struct VirtfsCoResetData { > > + V9fsPDU pdu; > > + bool done; > > +} VirtfsCoResetData; > > + > > +static void coroutine_fn virtfs_co_reset(void *opaque) > > +{ > > + VirtfsCoResetData *data = opaque; > > + > > + virtfs_reset(&data->pdu); > > + data->done = true; > > +} > > + > > +void v9fs_reset(V9fsState *s) > > +{ > > + VirtfsCoResetData data = { .pdu = { .s = s }, .done = false }; > > + Coroutine *co; > > + > > + while (!QLIST_EMPTY(&s->active_list)) { > > + aio_poll(qemu_get_aio_context(), true); > > + } > > + > > + co = qemu_coroutine_create(virtfs_co_reset, &data); > > + qemu_coroutine_enter(co); > > + > > + while (!data.done) { > > + aio_poll(qemu_get_aio_context(), true); > > + } > > +} > > + > > static void __attribute__((__constructor__)) v9fs_set_fd_limit(void) > > { > > struct rlimit rlim; > > diff --git a/hw/9pfs/9p.h b/hw/9pfs/9p.h > > index d539d2ebe9c0..6b69eaf24614 100644 > > --- a/hw/9pfs/9p.h > > +++ b/hw/9pfs/9p.h > > @@ -339,5 +339,6 @@ ssize_t pdu_unmarshal(V9fsPDU *pdu, size_t offset, const char *fmt, ...); > > V9fsPDU *pdu_alloc(V9fsState *s); > > void pdu_free(V9fsPDU *pdu); > > void pdu_submit(V9fsPDU *pdu); > > +void v9fs_reset(V9fsState *s); > > > > #endif > > diff --git a/hw/9pfs/virtio-9p-device.c b/hw/9pfs/virtio-9p-device.c > > index 009b43f6d045..b73d72aceb64 100644 > > --- a/hw/9pfs/virtio-9p-device.c > > +++ b/hw/9pfs/virtio-9p-device.c > > @@ -130,6 +130,13 @@ static void virtio_9p_device_unrealize(DeviceState *dev, Error **errp) > > 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) > > { > > @@ -188,6 +195,7 @@ static void virtio_9p_class_init(ObjectClass *klass, void *data) > > 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 = {
On Thu, Oct 06, 2016 at 03:12:10PM +0200, Greg Kurz wrote: > 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> > --- > hw/9pfs/9p.c | 31 +++++++++++++++++++++++++++++++ > hw/9pfs/9p.h | 1 + > hw/9pfs/virtio-9p-device.c | 8 ++++++++ > 3 files changed, 40 insertions(+) Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c index 119ee584969b..42137395037e 100644 --- a/hw/9pfs/9p.c +++ b/hw/9pfs/9p.c @@ -3522,6 +3522,37 @@ void v9fs_device_unrealize_common(V9fsState *s, Error **errp) g_free(s->tag); } + +typedef struct VirtfsCoResetData { + V9fsPDU pdu; + bool done; +} VirtfsCoResetData; + +static void coroutine_fn virtfs_co_reset(void *opaque) +{ + VirtfsCoResetData *data = opaque; + + virtfs_reset(&data->pdu); + data->done = true; +} + +void v9fs_reset(V9fsState *s) +{ + VirtfsCoResetData data = { .pdu = { .s = s }, .done = false }; + Coroutine *co; + + while (!QLIST_EMPTY(&s->active_list)) { + aio_poll(qemu_get_aio_context(), true); + } + + co = qemu_coroutine_create(virtfs_co_reset, &data); + qemu_coroutine_enter(co); + + while (!data.done) { + aio_poll(qemu_get_aio_context(), true); + } +} + static void __attribute__((__constructor__)) v9fs_set_fd_limit(void) { struct rlimit rlim; diff --git a/hw/9pfs/9p.h b/hw/9pfs/9p.h index d539d2ebe9c0..6b69eaf24614 100644 --- a/hw/9pfs/9p.h +++ b/hw/9pfs/9p.h @@ -339,5 +339,6 @@ ssize_t pdu_unmarshal(V9fsPDU *pdu, size_t offset, const char *fmt, ...); V9fsPDU *pdu_alloc(V9fsState *s); void pdu_free(V9fsPDU *pdu); void pdu_submit(V9fsPDU *pdu); +void v9fs_reset(V9fsState *s); #endif diff --git a/hw/9pfs/virtio-9p-device.c b/hw/9pfs/virtio-9p-device.c index 009b43f6d045..b73d72aceb64 100644 --- a/hw/9pfs/virtio-9p-device.c +++ b/hw/9pfs/virtio-9p-device.c @@ -130,6 +130,13 @@ static void virtio_9p_device_unrealize(DeviceState *dev, Error **errp) 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) { @@ -188,6 +195,7 @@ static void virtio_9p_class_init(ObjectClass *klass, void *data) 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 = {
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> --- hw/9pfs/9p.c | 31 +++++++++++++++++++++++++++++++ hw/9pfs/9p.h | 1 + hw/9pfs/virtio-9p-device.c | 8 ++++++++ 3 files changed, 40 insertions(+)