Add barrier fsync test case

Also changes the fsync prep helper to require passing in the actual
flag, not just a boolean for fsync vs fdatasync.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

src/io_uring.h

@@ -59,6 +59,7 @@ struct io_uring_sqe {
  * sqe->fsync_flags
  */
 #define IORING_FSYNC_DATASYNC	(1U << 0)
+#define IORING_FSYNC_BARRIER	(1U << 1)
 
 /*
  * IO completion data structure (Completion Queue Entry)

src/liburing.h

@@ -131,13 +131,12 @@ static inline void io_uring_prep_poll_remove(struct io_uring_sqe *sqe,
 }
 
 static inline void io_uring_prep_fsync(struct io_uring_sqe *sqe, int fd,
-				       int datasync)
+				       unsigned fsync_flags)
 {
 	memset(sqe, 0, sizeof(*sqe));
 	sqe->opcode = IORING_OP_FSYNC;
 	sqe->fd = fd;
-	if (datasync)
-		sqe->fsync_flags = IORING_FSYNC_DATASYNC;
+	sqe->fsync_flags = fsync_flags;
 }
 
 #endif

test/fsync.c

@@ -11,11 +11,10 @@
 
 #include "../src/liburing.h"
 
-int main(int argc, char *argv[])
+static int test_single_fsync(struct io_uring *ring)
 {
 	struct io_uring_cqe *cqe;
 	struct io_uring_sqe *sqe;
-	struct io_uring ring;
 	char buf[32];
 	int fd, ret;
 
@@ -26,33 +25,128 @@ int main(int argc, char *argv[])
 		return 1;
 	}
 
-	ret = io_uring_queue_init(1, &ring, 0);
+	sqe = io_uring_get_sqe(ring);
+	if (!sqe) {
+		printf("get sqe failed\n");
+		goto err;
+	}
+
+	io_uring_prep_fsync(sqe, fd, 0);
+
+	ret = io_uring_submit(ring);
+	if (ret <= 0) {
+		printf("sqe submit failed\n");
+		goto err;
+	}
+
+	ret = io_uring_wait_completion(ring, &cqe);
+	if (ret < 0) {
+		printf("wait completion %d\n", ret);
+		goto err;
+	}
+
+	unlink(buf);
+	return 0;
+err:
+	unlink(buf);
+	return 1;
+}
+
+static int test_barrier_fsync(struct io_uring *ring)
+{
+	struct io_uring_cqe *cqe;
+	struct io_uring_sqe *sqe;
+	struct iovec iovecs[4];
+	int i, fd, ret;
+	off_t off;
+
+	fd = open("testfile", O_WRONLY | O_CREAT, 0644);
+	if (fd < 0) {
+		perror("open");
+		return 1;
+	}
+
+	for (i = 0; i < 4; i++) {
+		iovecs[i].iov_base = malloc(4096);
+		iovecs[i].iov_len = 4096;
+	}
+
+	off = 0;
+	for (i = 0; i < 4; i++) {
+		sqe = io_uring_get_sqe(ring);
+		if (!sqe) {
+			printf("get sqe failed\n");
+			goto err;
+		}
+
+		io_uring_prep_writev(sqe, fd, &iovecs[i], 1, off);
+		sqe->user_data = 0;
+		off += 4096;
+	}
+
+	sqe = io_uring_get_sqe(ring);
+	if (!sqe) {
+		printf("get sqe failed\n");
+		goto err;
+	}
+
+	io_uring_prep_fsync(sqe, fd,
+				IORING_FSYNC_DATASYNC | IORING_FSYNC_BARRIER);
+	sqe->user_data = 1;
+
+	ret = io_uring_submit(ring);
+	if (ret <= 0) {
+		printf("sqe submit failed\n");
+		if (ret == EINVAL)
+			printf("kernel may not support barrier fsync yet\n");
+		goto err;
+	}
+
+	for (i = 0; i < 5; i++) {
+		ret = io_uring_wait_completion(ring, &cqe);
+		if (ret < 0) {
+			printf("child: wait completion %d\n", ret);
+			goto err;
+		}
+		if (i <= 3) {
+			if (cqe->user_data) {
+				printf("Got fsync early?\n");
+				goto err;
+			}
+		} else {
+			if (!cqe->user_data) {
+				printf("Got write late?\n");
+				goto err;
+			}
+		}
+	}
+
+	unlink("testfile");
+	return 0;
+err:
+	unlink("testfile");
+	return 1;
+}
+
+int main(int argc, char *argv[])
+{
+	struct io_uring ring;
+	int ret;
+
+	ret = io_uring_queue_init(8, &ring, 0);
 	if (ret) {
 		printf("ring setup failed\n");
 		return 1;
 
 	}
 
-	sqe = io_uring_get_sqe(&ring);
-	if (!sqe) {
-		printf("get sqe failed\n");
-		return 1;
-	}
+	ret = test_single_fsync(&ring);
+	if (ret)
+		return ret;
 
-	io_uring_prep_fsync(sqe, fd, 0);
+	ret = test_barrier_fsync(&ring);
+	if (ret)
+		return ret;
 
-	ret = io_uring_submit(&ring);
-	if (ret <= 0) {
-		printf("child: sqe submit failed\n");
-		return 1;
-	}
-
-	ret = io_uring_wait_completion(&ring, &cqe);
-	if (ret < 0) {
-		printf("child: wait completion %d\n", ret);
-		return 1;
-	}
-
-	unlink(buf);
 	return 0;
 }