[RFC v3 09/11] vduse: Add VDUSE_GET_DEV ioctl

[Xie Yongji <xieyongji@bytedance.com>]

This new ioctl will be used to retrieve the file descriptor
referring to userspace vDPA device to support reconnecting.

Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
---
 drivers/vdpa/vdpa_user/vduse_dev.c | 30 ++++++++++++++++++++++++++++++
 include/uapi/linux/vduse.h         |  1 +
 2 files changed, 31 insertions(+)

diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
index 1cf759bc5914..4d21203da5b6 100644
--- a/drivers/vdpa/vdpa_user/vduse_dev.c
+++ b/drivers/vdpa/vdpa_user/vduse_dev.c
@@ -872,9 +872,14 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
 static int vduse_dev_release(struct inode *inode, struct file *file)
 {
 	struct vduse_dev *dev = file->private_data;
+	struct vduse_dev_msg *msg;
 
 	vduse_kickfd_release(dev);
 	vduse_virqfd_release(dev);
+
+	while ((msg = vduse_dev_dequeue_msg(dev, &dev->recv_list)))
+		vduse_dev_enqueue_msg(dev, msg, &dev->send_list);
+
 	dev->connected = false;
 
 	return 0;
@@ -937,6 +942,28 @@ static struct vduse_dev *vduse_find_dev(u32 id)
 	return dev;
 }
 
+static int vduse_get_dev(u32 id)
+{
+	int fd;
+	char name[64];
+	struct vduse_dev *dev = vduse_find_dev(id);
+
+	if (!dev)
+		return -EINVAL;
+
+	if (dev->connected)
+		return -EBUSY;
+
+	snprintf(name, sizeof(name), "[vduse-dev:%u]", dev->id);
+	fd = anon_inode_getfd(name, &vduse_dev_fops, dev, O_RDWR | O_CLOEXEC);
+	if (fd < 0)
+		return fd;
+
+	dev->connected = true;
+
+	return fd;
+}
+
 static int vduse_destroy_dev(u32 id)
 {
 	struct vduse_dev *dev = vduse_find_dev(id);
@@ -1024,6 +1051,9 @@ static long vduse_ioctl(struct file *file, unsigned int cmd,
 		ret = vduse_create_dev(&config);
 		break;
 	}
+	case VDUSE_GET_DEV:
+		ret = vduse_get_dev(arg);
+		break;
 	case VDUSE_DESTROY_DEV:
 		ret = vduse_destroy_dev(arg);
 		break;
diff --git a/include/uapi/linux/vduse.h b/include/uapi/linux/vduse.h
index 9fb555ddcfbd..b3694f0d3b77 100644
--- a/include/uapi/linux/vduse.h
+++ b/include/uapi/linux/vduse.h
@@ -117,6 +117,7 @@ struct vduse_vq_eventfd {
 
 #define VDUSE_CREATE_DEV	_IOW(VDUSE_BASE, 0x01, struct vduse_dev_config)
 #define VDUSE_DESTROY_DEV	_IO(VDUSE_BASE, 0x02)
+#define VDUSE_GET_DEV		_IO(VDUSE_BASE, 0x03)
 
 #define VDUSE_IOTLB_GET_FD	_IOWR(VDUSE_BASE, 0x04, struct vduse_iotlb_entry)
 #define VDUSE_VQ_SETUP_KICKFD	_IOW(VDUSE_BASE, 0x05, struct vduse_vq_eventfd)
-- 
2.11.0