[PATCH 01/13] io_uring/nop: add support for testing registered files and buffers

[Jens Axboe <axboe@xxxxxxxxx>]

Useful for testing performance/efficiency impact of registered files
and buffers, vs (particularly) non-registered files.

Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
 include/uapi/linux/io_uring.h |  3 +++
 io_uring/nop.c                | 49 +++++++++++++++++++++++++++++++----
 2 files changed, 47 insertions(+), 5 deletions(-)

diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 65b7417c1b05..024745283783 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -416,6 +416,9 @@ enum io_uring_msg_ring_flags {
  * IORING_NOP_INJECT_RESULT	Inject result from sqe->result
  */
 #define IORING_NOP_INJECT_RESULT	(1U << 0)
+#define IORING_NOP_FILE			(1U << 1)
+#define IORING_NOP_FIXED_FILE		(1U << 2)
+#define IORING_NOP_FIXED_BUFFER		(1U << 3)
 
 /*
  * IO completion data structure (Completion Queue Entry)
diff --git a/io_uring/nop.c b/io_uring/nop.c
index a5bcf3d6984f..2c7a22ba4053 100644
--- a/io_uring/nop.c
+++ b/io_uring/nop.c
@@ -8,35 +8,74 @@
 #include <uapi/linux/io_uring.h>
 
 #include "io_uring.h"
+#include "rsrc.h"
 #include "nop.h"
 
 struct io_nop {
 	/* NOTE: kiocb has the file as the first member, so don't do it here */
 	struct file     *file;
 	int             result;
+	int		fd;
+	int		buffer;
+	unsigned int	flags;
 };
 
+#define NOP_FLAGS	(IORING_NOP_INJECT_RESULT | IORING_NOP_FIXED_FILE | \
+			 IORING_NOP_FIXED_BUFFER | IORING_NOP_FILE)
+
 int io_nop_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 {
-	unsigned int flags;
 	struct io_nop *nop = io_kiocb_to_cmd(req, struct io_nop);
 
-	flags = READ_ONCE(sqe->nop_flags);
-	if (flags & ~IORING_NOP_INJECT_RESULT)
+	nop->flags = READ_ONCE(sqe->nop_flags);
+	if (nop->flags & ~NOP_FLAGS)
 		return -EINVAL;
 
-	if (flags & IORING_NOP_INJECT_RESULT)
+	if (nop->flags & IORING_NOP_INJECT_RESULT)
 		nop->result = READ_ONCE(sqe->len);
 	else
 		nop->result = 0;
+	if (nop->flags & IORING_NOP_FIXED_FILE)
+		nop->fd = READ_ONCE(sqe->fd);
+	if (nop->flags & IORING_NOP_FIXED_BUFFER)
+		nop->buffer = READ_ONCE(sqe->buf_index);
 	return 0;
 }
 
 int io_nop(struct io_kiocb *req, unsigned int issue_flags)
 {
 	struct io_nop *nop = io_kiocb_to_cmd(req, struct io_nop);
+	int ret = nop->result;
+
+	if (nop->flags & IORING_NOP_FILE) {
+		if (nop->flags & IORING_NOP_FIXED_FILE) {
+			req->file = io_file_get_fixed(req, nop->fd, issue_flags);
+			req->flags |= REQ_F_FIXED_FILE;
+		} else {
+			req->file = io_file_get_normal(req, nop->fd);
+		}
+		if (!req->file) {
+			ret = -EBADF;
+			goto done;
+		}
+	}
+	if (nop->flags & IORING_NOP_FIXED_BUFFER) {
+		struct io_ring_ctx *ctx = req->ctx;
+		struct io_mapped_ubuf *imu;
+		int idx;
 
-	if (nop->result < 0)
+		ret = -EFAULT;
+		io_ring_submit_lock(ctx, issue_flags);
+		if (nop->buffer < ctx->nr_user_bufs) {
+			idx = array_index_nospec(nop->buffer, ctx->nr_user_bufs);
+			imu = READ_ONCE(ctx->user_bufs[idx]);
+			io_req_set_rsrc_node(req, ctx);
+			ret = 0;
+		}
+		io_ring_submit_unlock(ctx, issue_flags);
+	}
+done:
+	if (ret < 0)
 		req_set_fail(req);
 	io_req_set_res(req, nop->result, 0);
 	return IOU_OK;
-- 
2.45.2