From 5c6e5d27451267c650d88a70a0f49563383d40c5 Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@kernel.dk>
Date: Wed, 15 May 2019 14:07:52 -0600
Subject: examples/link-cp: improvements

Add short read requeue and abort on error.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 examples/link-cp.c | 41 +++++++++++++++++++++++++++++------------
 1 file changed, 29 insertions(+), 12 deletions(-)

diff --git a/examples/link-cp.c b/examples/link-cp.c
index 9ac4658..8f29956 100644
--- a/examples/link-cp.c
+++ b/examples/link-cp.c
@@ -19,10 +19,13 @@
 #define BS	(32*1024)
 
 struct io_data {
+	size_t offset;
+	int index;
 	struct iovec iov;
 };
 
 static int infd, outfd;
+static unsigned inflight;
 
 static int setup_context(unsigned entries, struct io_uring *ring)
 {
@@ -59,36 +62,48 @@ static int get_file_size(int fd, off_t *size)
 	return -1;
 }
 
-static int queue_rw_pair(struct io_uring *ring, off_t size, off_t offset)
+static void queue_rw_pair(struct io_uring *ring, off_t size, off_t offset)
 {
 	struct io_uring_sqe *sqe;
 	struct io_data *data;
 
 	data = malloc(size + sizeof(*data));
+	data->index = 0;
+	data->offset = offset;
 	data->iov.iov_base = data + 1;
 	data->iov.iov_len = size;
 
 	sqe = io_uring_get_sqe(ring);
 	io_uring_prep_readv(sqe, infd, &data->iov, 1, offset);
 	sqe->flags |= IOSQE_IO_LINK;
+	io_uring_sqe_set_data(sqe, data);
 
 	sqe = io_uring_get_sqe(ring);
 	io_uring_prep_writev(sqe, outfd, &data->iov, 1, offset);
 	io_uring_sqe_set_data(sqe, data);
-	return 0;
 }
 
-static void handle_cqe(struct io_uring *ring, struct io_uring_cqe *cqe)
+static int handle_cqe(struct io_uring *ring, struct io_uring_cqe *cqe)
 {
-	struct io_data *data;
+	struct io_data *data = io_uring_cqe_get_data(cqe);
+	int ret = 0;
+
+	data->index++;
 
-	if (cqe->res < 0)
-		printf("cqe error: %s\n", strerror(cqe->res));
+	if (cqe->res < 0) {
+		if (cqe->res == -ECANCELED) {
+			queue_rw_pair(ring, BS, data->offset);
+			inflight += 2;
+		} else {
+			printf("cqe error: %s\n", strerror(cqe->res));
+			ret = 1;
+		}
+	}
 
-	data = io_uring_cqe_get_data(cqe);
-	if (data)
+	if (data->index == 2)
 		free(data);
 	io_uring_cqe_seen(ring, cqe);
+	return ret;
 }
 
 static int copy_file(struct io_uring *ring, off_t insize)
@@ -96,10 +111,8 @@ static int copy_file(struct io_uring *ring, off_t insize)
 	struct io_uring_cqe *cqe;
 	size_t this_size;
 	off_t offset;
-	int inflight;
 
 	offset = 0;
-	inflight = 0;
 	while (insize) {
 		int has_inflight = inflight;
 		int depth;
@@ -125,8 +138,12 @@ static int copy_file(struct io_uring *ring, off_t insize)
 			int ret;
 
 			ret = io_uring_wait_cqe(ring, &cqe);
-			assert(ret >= 0);
-			handle_cqe(ring, cqe);
+			if (ret < 0) {
+				printf("wait cqe: %s\n", strerror(ret));
+				return 1;
+			}
+			if (handle_cqe(ring, cqe))
+				return 1;
 			inflight--;
 		}
 	}
-- 
cgit