Match const signatures in io_uring_prep_* to native functions

io_uring_prep_{readv,writev,read_fixed,write_fixed}() take
non-const arguments that are const in the native functions
that they mimic. Make those arguments const.

Signed-off-by: Ian Gulliver <git@flamingcow.io>

man/io_uring_setup.2

@@ -172,7 +172,7 @@ submission queue can be mapped with a call like:
 .in +4n
 .EX
 ptr = mmap(0, sq_off.array + sq_entries * sizeof(__u32),
-           PROT_READ|PROT_WRITE|MAP_SHARED|MAP_POPULATE,
+           PROT_READ|PROT_WRITE, MAP_SHARED|MAP_POPULATE,
            ring_fd, IORING_OFF_SQ_RING);
 .EE
 .in
@@ -229,7 +229,7 @@ The array of submission queue entries is mapped with:
 .in +4n
 .EX
 sqentries = mmap(0, sq_entries * sizeof(struct io_uring_sqe),
-                 PROT_READ|PROT_WRITE|MAP_SHARED|MAP_POPULATE,
+                 PROT_READ|PROT_WRITE, MAP_SHARED|MAP_POPULATE,
                  ring_fd, IORING_OFF_SQES);
 .EE
 .in
@@ -260,7 +260,7 @@ from the queue itself, and can be mapped with:
 .in +4n
 .EX
 ptr = mmap(0, cq_off.cqes + cq_entries * sizeof(struct io_uring_cqe),
-           PROT_READ|PROT_WRITE|MAP_SHARED|MAP_POPULATE, ring_fd,
+           PROT_READ|PROT_WRITE, MAP_SHARED|MAP_POPULATE, ring_fd,
            IORING_OFF_CQ_RING);
 .EE
 .in

src/io_uring.h

@@ -26,6 +26,7 @@ struct io_uring_sqe {
 		__kernel_rwf_t	rw_flags;
 		__u32		fsync_flags;
 		__u16		poll_events;
+		__u32		sync_range_flags;
 	};
 	__u64	user_data;	/* data to be passed back at completion time */
 	union {
@@ -38,8 +39,8 @@ struct io_uring_sqe {
  * sqe->flags
  */
 #define IOSQE_FIXED_FILE	(1U << 0)	/* use fixed fileset */
-#define IOSQE_IO_DRAIN		(1U << 1)
-#define IOSQE_IO_LINK		(1U << 2)
+#define IOSQE_IO_DRAIN		(1U << 1)	/* issue after inflight IO */
+#define IOSQE_IO_LINK		(1U << 2)	/* next IO depends on this one */
 
 /*
  * io_uring_setup() flags
@@ -56,6 +57,7 @@ struct io_uring_sqe {
 #define IORING_OP_WRITE_FIXED	5
 #define IORING_OP_POLL_ADD	6
 #define IORING_OP_POLL_REMOVE	7
+#define IORING_OP_SYNC_FILE_RANGE	8
 
 /*
  * sqe->fsync_flags
@@ -135,5 +137,7 @@ struct io_uring_params {
 #define IORING_UNREGISTER_BUFFERS	1
 #define IORING_REGISTER_FILES		2
 #define IORING_UNREGISTER_FILES		3
+#define IORING_REGISTER_EVENTFD		4
+#define IORING_UNREGISTER_EVENTFD	5
 
 #endif

src/liburing.h

@@ -7,6 +7,7 @@ extern "C" {
 
 #include <sys/uio.h>
 #include <signal.h>
+#include <string.h>
 #include <inttypes.h>
 #include "compat.h"
 #include "io_uring.h"
@@ -105,7 +106,8 @@ static inline void *io_uring_cqe_get_data(struct io_uring_cqe *cqe)
 }
 
 static inline void io_uring_prep_rw(int op, struct io_uring_sqe *sqe, int fd,
-				    void *addr, unsigned len, off_t offset)
+				    const void *addr, unsigned len,
+				    off_t offset)
 {
 	memset(sqe, 0, sizeof(*sqe));
 	sqe->opcode = op;
@@ -116,8 +118,8 @@ static inline void io_uring_prep_rw(int op, struct io_uring_sqe *sqe, int fd,
 }
 
 static inline void io_uring_prep_readv(struct io_uring_sqe *sqe, int fd,
-				       struct iovec *iovecs, unsigned nr_vecs,
-				       off_t offset)
+				       const struct iovec *iovecs,
+				       unsigned nr_vecs, off_t offset)
 {
 	io_uring_prep_rw(IORING_OP_READV, sqe, fd, iovecs, nr_vecs, offset);
 }
@@ -130,14 +132,14 @@ static inline void io_uring_prep_read_fixed(struct io_uring_sqe *sqe, int fd,
 }
 
 static inline void io_uring_prep_writev(struct io_uring_sqe *sqe, int fd,
-				        struct iovec *iovecs, unsigned nr_vecs,
-					off_t offset)
+					const struct iovec *iovecs,
+					unsigned nr_vecs, off_t offset)
 {
 	io_uring_prep_rw(IORING_OP_WRITEV, sqe, fd, iovecs, nr_vecs, offset);
 }
 
 static inline void io_uring_prep_write_fixed(struct io_uring_sqe *sqe, int fd,
-					     void *buf, unsigned nbytes,
+					     const void *buf, unsigned nbytes,
 					     off_t offset)
 {
 	io_uring_prep_rw(IORING_OP_WRITE_FIXED, sqe, fd, buf, nbytes, offset);