Return path: Open a return path on QEMUFile for sockets
Postcopy needs a method to send messages from the destination back to
the source, this is the 'return path'.
Wire it up for 'socket' QEMUFile's.
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
diff --git a/include/migration/qemu-file.h b/include/migration/qemu-file.h
index 66e741f..b5d08d2 100644
--- a/include/migration/qemu-file.h
+++ b/include/migration/qemu-file.h
@@ -89,6 +89,11 @@
uint64_t *bytes_sent);
/*
+ * Return a QEMUFile for comms in the opposite direction
+ */
+typedef QEMUFile *(QEMURetPathFunc)(void *opaque);
+
+/*
* Stop any read or write (depending on flags) on the underlying
* transport on the QEMUFile.
* Existing blocking reads/writes must be woken
@@ -106,6 +111,7 @@
QEMURamHookFunc *after_ram_iterate;
QEMURamHookFunc *hook_ram_load;
QEMURamSaveFunc *save_page;
+ QEMURetPathFunc *get_return_path;
QEMUFileShutdownFunc *shut_down;
} QEMUFileOps;
@@ -196,6 +202,7 @@
int qemu_file_get_error(QEMUFile *f);
void qemu_file_set_error(QEMUFile *f, int ret);
int qemu_file_shutdown(QEMUFile *f);
+QEMUFile *qemu_file_get_return_path(QEMUFile *f);
void qemu_fflush(QEMUFile *f);
void qemu_file_set_blocking(QEMUFile *f, bool block);
diff --git a/migration/qemu-file-unix.c b/migration/qemu-file-unix.c
index 809bf07..bcb744b 100644
--- a/migration/qemu-file-unix.c
+++ b/migration/qemu-file-unix.c
@@ -97,6 +97,56 @@
}
}
+static int socket_return_close(void *opaque)
+{
+ QEMUFileSocket *s = opaque;
+ /*
+ * Note: We don't close the socket, that should be done by the forward
+ * path.
+ */
+ g_free(s);
+ return 0;
+}
+
+static const QEMUFileOps socket_return_read_ops = {
+ .get_fd = socket_get_fd,
+ .get_buffer = socket_get_buffer,
+ .close = socket_return_close,
+ .shut_down = socket_shutdown,
+};
+
+static const QEMUFileOps socket_return_write_ops = {
+ .get_fd = socket_get_fd,
+ .writev_buffer = socket_writev_buffer,
+ .close = socket_return_close,
+ .shut_down = socket_shutdown,
+};
+
+/*
+ * Give a QEMUFile* off the same socket but data in the opposite
+ * direction.
+ */
+static QEMUFile *socket_get_return_path(void *opaque)
+{
+ QEMUFileSocket *forward = opaque;
+ QEMUFileSocket *reverse;
+
+ if (qemu_file_get_error(forward->file)) {
+ /* If the forward file is in error, don't try and open a return */
+ return NULL;
+ }
+
+ reverse = g_malloc0(sizeof(QEMUFileSocket));
+ reverse->fd = forward->fd;
+ /* I don't think there's a better way to tell which direction 'this' is */
+ if (forward->file->ops->get_buffer != NULL) {
+ /* being called from the read side, so we need to be able to write */
+ return qemu_fopen_ops(reverse, &socket_return_write_ops);
+ } else {
+ return qemu_fopen_ops(reverse, &socket_return_read_ops);
+ }
+}
+
static ssize_t unix_writev_buffer(void *opaque, struct iovec *iov, int iovcnt,
int64_t pos)
{
@@ -206,18 +256,19 @@
}
static const QEMUFileOps socket_read_ops = {
- .get_fd = socket_get_fd,
- .get_buffer = socket_get_buffer,
- .close = socket_close,
- .shut_down = socket_shutdown
-
+ .get_fd = socket_get_fd,
+ .get_buffer = socket_get_buffer,
+ .close = socket_close,
+ .shut_down = socket_shutdown,
+ .get_return_path = socket_get_return_path
};
static const QEMUFileOps socket_write_ops = {
- .get_fd = socket_get_fd,
- .writev_buffer = socket_writev_buffer,
- .close = socket_close,
- .shut_down = socket_shutdown
+ .get_fd = socket_get_fd,
+ .writev_buffer = socket_writev_buffer,
+ .close = socket_close,
+ .shut_down = socket_shutdown,
+ .get_return_path = socket_get_return_path
};
QEMUFile *qemu_fopen_socket(int fd, const char *mode)
diff --git a/migration/qemu-file.c b/migration/qemu-file.c
index 9ec2267..0bbd257 100644
--- a/migration/qemu-file.c
+++ b/migration/qemu-file.c
@@ -44,6 +44,18 @@
return f->ops->shut_down(f->opaque, true, true);
}
+/*
+ * Result: QEMUFile* for a 'return path' for comms in the opposite direction
+ * NULL if not available
+ */
+QEMUFile *qemu_file_get_return_path(QEMUFile *f)
+{
+ if (!f->ops->get_return_path) {
+ return NULL;
+ }
+ return f->ops->get_return_path(f->opaque);
+}
+
bool qemu_file_mode_is_not_valid(const char *mode)
{
if (mode == NULL ||
