Update API

- io_uring_sqe added a data field that's passed back at completion
- io_uring_sqe added an index field, for fixed buffer locations
- io_uring_setup(2) system call added a 'nr_iovecs' field

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

src/io_uring.c

@@ -189,11 +189,12 @@ err:
  * contains the necessary information to read/write to the rings.
  */
 int io_uring_queue_init(unsigned entries, struct io_uring_params *p,
-			struct iovec *iovecs, struct io_uring *ring)
+			struct iovec *iovecs, unsigned nr_iovecs,
+			struct io_uring *ring)
 {
 	int fd, ret;
 
-	fd = io_uring_setup(entries, iovecs, p);
+	fd = io_uring_setup(entries, iovecs, nr_iovecs, p);
 	if (fd < 0)
 		return fd;
 

src/io_uring.h

@@ -15,20 +15,23 @@
  * IO submission data structure (Submission Queue Entry)
  */
 struct io_uring_sqe {
-	__u8	opcode;
-	__u8	flags;
-	__u16	ioprio;
-	__s32	fd;
-	__u64	off;
+	__u8	opcode;		/* type of operation for this sqe */
+	__u8	flags;		/* as of now unused */
+	__u16	ioprio;		/* ioprio for the request */
+	__s32	fd;		/* file descriptor to do IO on */
+	__u64	off;		/* offset into file */
 	union {
-		void	*addr;
+		void	*addr;	/* buffer or iovecs */
 		__u64	__pad;
 	};
-	__u32	len;
+	__u32	len;		/* buffer size or number of iovecs */
 	union {
 		__kernel_rwf_t	rw_flags;
 		__u32		__resv;
 	};
+	__u16	index;		/* index into fixed buffers, if used */
+	__u16	__pad2[3];
+	__u64	data;		/* data to be passed back at completion time */
 };
 
 /*
@@ -50,7 +53,7 @@ struct io_uring_sqe {
  * IO completion data structure (Completion Queue Entry)
  */
 struct io_uring_cqe {
-	__u64	index;		/* what sqe this event came from */
+	__u64	data;		/* sqe->data submission passed back */
 	__s32	res;		/* result code for this event */
 	__u32	flags;
 };

src/liburing.h

@@ -44,7 +44,7 @@ struct io_uring {
  * System calls
  */
 extern int io_uring_setup(unsigned entries, struct iovec *iovecs,
-	struct io_uring_params *p);
+	unsigned nr_iovecs, struct io_uring_params *p);
 extern int io_uring_enter(unsigned fd, unsigned to_submit,
 	unsigned min_complete, unsigned flags);
 
@@ -52,7 +52,7 @@ extern int io_uring_enter(unsigned fd, unsigned to_submit,
  * Library interface
  */
 extern int io_uring_queue_init(unsigned entries, struct io_uring_params *p,
-	struct iovec *iovecs, struct io_uring *ring);
+	struct iovec *iovecs, unsigned nr_iovecs, struct io_uring *ring);
 extern void io_uring_queue_exit(struct io_uring *ring);
 extern int io_uring_get_completion(struct io_uring *ring,
 	struct io_uring_cqe **cqe_ptr);
@@ -61,10 +61,4 @@ extern int io_uring_wait_completion(struct io_uring *ring,
 extern int io_uring_submit(struct io_uring *ring);
 extern struct io_uring_sqe *io_uring_get_sqe(struct io_uring *ring);
 
-static inline struct io_uring_sqe *
-io_uring_sqe_from_cqe(struct io_uring *ring, struct io_uring_cqe *cqe)
-{
-	return &ring->sq.sqes[cqe->index];
-}
-
 #endif

src/syscall.c

@@ -18,9 +18,9 @@
 #endif
 
 int io_uring_setup(unsigned int entries, struct iovec *iovecs,
-		   struct io_uring_params *p)
+		   unsigned nr_iovecs, struct io_uring_params *p)
 {
-	return syscall(__NR_sys_io_uring_setup, entries, iovecs, p);
+	return syscall(__NR_sys_io_uring_setup, entries, iovecs, nr_iovecs, p);
 }
 
 int io_uring_enter(int fd, unsigned int to_submit, unsigned int min_complete,