[PATCH v6 2/3] vhost: add EVENTFD_COPY2 ioctl

[Pavel Boldin <pboldin@mirantis.com>]

Signed-off-by: Pavel Boldin <pboldin@mirantis.com>
---
 lib/librte_vhost/eventfd_link/eventfd_link.c | 61 ++++++++++++++++++++++++++++
 lib/librte_vhost/eventfd_link/eventfd_link.h | 28 ++++++++++---
 2 files changed, 84 insertions(+), 5 deletions(-)

diff --git a/lib/librte_vhost/eventfd_link/eventfd_link.c b/lib/librte_vhost/eventfd_link/eventfd_link.c
index 7cbebd4..c54a938 100644
--- a/lib/librte_vhost/eventfd_link/eventfd_link.c
+++ b/lib/librte_vhost/eventfd_link/eventfd_link.c
@@ -78,6 +78,64 @@ fget_from_files(struct files_struct *files, unsigned fd)
 }
 
 static long
+eventfd_link_ioctl_copy2(unsigned long arg)
+{
+	void __user *argp = (void __user *) arg;
+	struct task_struct *task_target = NULL;
+	struct file *file;
+	struct files_struct *files;
+	struct eventfd_copy2 eventfd_copy2;
+	long ret = -EFAULT;
+
+	if (copy_from_user(&eventfd_copy2, argp, sizeof(struct eventfd_copy2)))
+		goto out;
+
+	/*
+	 * Find the task struct for the target pid
+	 */
+	ret = -ESRCH;
+
+	task_target =
+		get_pid_task(find_vpid(eventfd_copy2.pid), PIDTYPE_PID);
+	if (task_target == NULL) {
+		pr_info("Unable to find pid %d\n", eventfd_copy2.pid);
+		goto out;
+	}
+
+	ret = -ESTALE;
+	files = get_files_struct(task_target);
+	if (files == NULL) {
+		pr_info("Failed to get target files struct\n");
+		goto out_task;
+	}
+
+	ret = -EBADF;
+	file = fget_from_files(files, eventfd_copy2.fd);
+	put_files_struct(files);
+
+	if (file == NULL) {
+		pr_info("Failed to get fd %d from target\n", eventfd_copy2.fd);
+		goto out_task;
+	}
+
+	/*
+	 * Install the file struct from the target process into the
+	 * newly allocated file desciptor of the source process.
+	 */
+	ret = get_unused_fd_flags(eventfd_copy2.flags);
+	if (ret < 0) {
+		fput(file);
+		goto out_task;
+	}
+	fd_install(ret, file);
+
+out_task:
+	put_task_struct(task_target);
+out:
+	return ret;
+}
+
+static long
 eventfd_link_ioctl_copy(unsigned long arg)
 {
 	void __user *argp = (void __user *) arg;
@@ -176,6 +234,9 @@ eventfd_link_ioctl(struct file *f, unsigned int ioctl, unsigned long arg)
 	case EVENTFD_COPY:
 		ret = eventfd_link_ioctl_copy(arg);
 		break;
+	case EVENTFD_COPY2:
+		ret = eventfd_link_ioctl_copy2(arg);
+		break;
 	}
 
 	return ret;
diff --git a/lib/librte_vhost/eventfd_link/eventfd_link.h b/lib/librte_vhost/eventfd_link/eventfd_link.h
index ea619ec..5ebc20b 100644
--- a/lib/librte_vhost/eventfd_link/eventfd_link.h
+++ b/lib/librte_vhost/eventfd_link/eventfd_link.h
@@ -61,11 +61,6 @@
 #define _EVENTFD_LINK_H_
 
 /*
- * ioctl to copy an fd entry in calling process to an fd in a target process
- */
-#define EVENTFD_COPY 1
-
-/*
  * arguements for the EVENTFD_COPY ioctl
  */
 struct eventfd_copy {
@@ -73,4 +68,27 @@ struct eventfd_copy {
 	unsigned source_fd; /* fd in the calling pid */
 	pid_t target_pid; /* pid of the target pid */
 };
+
+/*
+ * ioctl to copy an fd entry in calling process to an fd in a target process
+ * NOTE: this one should be
+ * #define EVENTFD_COPY _IOWR('D', 1, struct eventfd_copy) actually
+ */
+#define EVENTFD_COPY 1
+
+/*
+ * arguments for the EVENTFD_COPY2 ioctl
+ */
+struct eventfd_copy2 {
+	unsigned fd; /* fd to steal */
+	pid_t pid; /* pid of the process to steal from */
+	unsigned flags; /* flags to allocate new fd with */
+};
+
+/*
+ * ioctl to copy an fd entry from the target process into newly allocated
+ * fd in the calling process
+ */
+#define EVENTFD_COPY2 _IOW('D', 2, struct eventfd_copy2)
+
 #endif /* _EVENTFD_LINK_H_ */
-- 
1.9.1