[PATCH for-next v2 1/4] io_uring: introduce io_uring_cmd_import_fixed

[Kanchan Joshi <joshi.k@samsung.com>]

From: Anuj Gupta <anuj20.g@samsung.com>

This is a new helper that callers can use to obtain a bvec iterator for
the previously mapped buffer. This is preparatory work to enable
fixed-buffer support for io_uring_cmd.

Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
---
 include/linux/io_uring.h |  7 +++++++
 io_uring/uring_cmd.c     | 10 ++++++++++
 2 files changed, 17 insertions(+)

diff --git a/include/linux/io_uring.h b/include/linux/io_uring.h
index 58676c0a398f..60aba10468fc 100644
--- a/include/linux/io_uring.h
+++ b/include/linux/io_uring.h
@@ -32,6 +32,8 @@ struct io_uring_cmd {
 };
 
 #if defined(CONFIG_IO_URING)
+int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
+		struct iov_iter *iter, void *ioucmd)
 void io_uring_cmd_done(struct io_uring_cmd *cmd, ssize_t ret, ssize_t res2);
 void io_uring_cmd_complete_in_task(struct io_uring_cmd *ioucmd,
 			void (*task_work_cb)(struct io_uring_cmd *));
@@ -59,6 +61,11 @@ static inline void io_uring_free(struct task_struct *tsk)
 		__io_uring_free(tsk);
 }
 #else
+int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
+		struct iov_iter *iter, void *ioucmd)
+{
+	return -1;
+}
 static inline void io_uring_cmd_done(struct io_uring_cmd *cmd, ssize_t ret,
 		ssize_t ret2)
 {
diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
index 8900856fa588..ff65cc8ab6cc 100644
--- a/io_uring/uring_cmd.c
+++ b/io_uring/uring_cmd.c
@@ -121,3 +121,13 @@ int io_uring_cmd(struct io_kiocb *req, unsigned int issue_flags)
 
 	return IOU_ISSUE_SKIP_COMPLETE;
 }
+
+int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len,
+		int rw, struct iov_iter *iter, void *ioucmd)
+{
+	struct io_kiocb *req = container_of(ioucmd, struct io_kiocb, uring_cmd);
+	struct io_mapped_ubuf *imu = req->imu;
+
+	return io_import_fixed(rw, iter, imu, ubuf, len);
+}
+EXPORT_SYMBOL_GPL(io_uring_cmd_import_fixed);
-- 
2.25.1