iscsi-scst: Kernel 3.19 build fix

Change the data type of iscsi_conn.read_iov into struct kvec * and
switch from iscsi_conn.read_size to iscsi_conn.read_msg.count for
kernel version 3.19 and later. Cast the return type of
get_zeroed_page() to void * since with this patch the read_iov
data type depends on the kernel version. Remove the (void __force
__user *) casts when assigning to iov_base since for a kvec iov_base
is a kernel pointer instead of a user space pointer. Switch to
iov_iter_kvec() to initialize conn->read_msg.msg_iter.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>

iscsi-scst/kernel/conn.c

@@ -895,7 +895,7 @@ static int iscsi_conn_alloc(struct iscsi_session *session,
 		       (unsigned long long int)session->sid, info->cid);
 
 	/* Changing it, change ISCSI_CONN_IOV_MAX as well !! */
-	conn->read_iov = (struct iovec *)get_zeroed_page(GFP_KERNEL);
+	conn->read_iov = (void *)get_zeroed_page(GFP_KERNEL);
 	if (conn->read_iov == NULL) {
 		res = -ENOMEM;
 		goto out_err_free_conn;

iscsi-scst/kernel/iscsi.c

@@ -1444,13 +1444,18 @@ static void cmnd_prepare_get_rejected_immed_data(struct iscsi_cmnd *cmnd)
 	for (s = size, i = 0; s > 0; i++, s -= e) {
 		/* We already checked pdu.datasize in check_segment_length() */
 		sBUG_ON(i >= ISCSI_CONN_IOV_MAX);
-		conn->read_iov[i].iov_base = (void __force __user *)addr;
+		conn->read_iov[i].iov_base = addr;
 		e = min_t(u32, s, PAGE_SIZE);
 		conn->read_iov[i].iov_len = e;
 	}
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(3, 19, 0)
+	iov_iter_kvec(&conn->read_msg.msg_iter, READ | ITER_KVEC,
+		      conn->read_iov, i, size);
+#else
 	conn->read_msg.msg_iov = conn->read_iov;
 	conn->read_msg.msg_iovlen = i;
 	conn->read_size = size;
+#endif
 
 out:
 	TRACE_EXIT();
@@ -1595,9 +1600,14 @@ static int cmnd_prepare_recv_pdu(struct iscsi_conn *conn,
 	}
 
 	i++;
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(3, 19, 0)
+	iov_iter_kvec(&conn->read_msg.msg_iter, READ | ITER_KVEC,
+		      conn->read_iov, i, read_size);
+#else
 	conn->read_msg.msg_iov = conn->read_iov;
 	conn->read_msg.msg_iovlen = i;
 	conn->read_size = read_size;
+#endif
 
 	TRACE_DBG("msg_iov=%p, msg_iovlen=%u", conn->read_iov, i);
 
@@ -1761,7 +1771,7 @@ static int nop_out_start(struct iscsi_cmnd *cmnd)
 
 			for (i = 0; i < cmnd->sg_cnt; i++) {
 				conn->read_iov[i].iov_base =
-					(void __force __user *)(page_address(sg_page(&sg[i])));
+					page_address(sg_page(&sg[i]));
 				tmp = min_t(u32, size, PAGE_SIZE);
 				conn->read_iov[i].iov_len = tmp;
 				size -= tmp;
@@ -1775,7 +1785,7 @@ static int nop_out_start(struct iscsi_cmnd *cmnd)
 			 */
 			for (i = 0; i < (signed)ISCSI_CONN_IOV_MAX; i++) {
 				conn->read_iov[i].iov_base =
-					(void __force __user *)(page_address(dummy_page));
+					page_address(dummy_page);
 				tmp = min_t(u32, size, PAGE_SIZE);
 				conn->read_iov[i].iov_len = tmp;
 				size -= tmp;
@@ -1785,9 +1795,14 @@ static int nop_out_start(struct iscsi_cmnd *cmnd)
 			sBUG_ON(size != 0);
 		}
 
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(3, 19, 0)
+		iov_iter_kvec(&conn->read_msg.msg_iter, READ | ITER_KVEC,
+			      conn->read_iov, i, cmnd->pdu.datasize);
+#else
 		conn->read_msg.msg_iov = conn->read_iov;
 		conn->read_msg.msg_iovlen = i;
 		conn->read_size = cmnd->pdu.datasize;
+#endif
 		TRACE_DBG("msg_iov=%p, msg_iovlen=%d", conn->read_iov, i);
 	}
 

iscsi-scst/kernel/iscsi.h

@@ -285,9 +285,13 @@ struct iscsi_conn {
 	 */
 	struct iscsi_cmnd *read_cmnd;
 	struct msghdr read_msg;
-	u32 read_size;
 	int read_state;
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(3, 19, 0)
+	struct kvec *read_iov;
+#else
+	u32 read_size;
 	struct iovec *read_iov;
+#endif
 	struct task_struct *rx_task;
 	uint32_t rpadding;
 

iscsi-scst/kernel/nthread.c

@@ -615,11 +615,16 @@ static void start_close_conn(struct iscsi_conn *conn)
 static inline void iscsi_conn_init_read(struct iscsi_conn *conn,
 	void *data, size_t len)
 {
-	conn->read_iov[0].iov_base = (void __force __user *)data;
+	conn->read_iov[0].iov_base = data;
 	conn->read_iov[0].iov_len = len;
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(3, 19, 0)
+	iov_iter_kvec(&conn->read_msg.msg_iter, READ | ITER_KVEC,
+		      conn->read_iov, 1, len);
+#else
 	conn->read_msg.msg_iov = conn->read_iov;
 	conn->read_msg.msg_iovlen = 1;
 	conn->read_size = len;
+#endif
 	return;
 }
 
@@ -698,7 +703,11 @@ static int do_recv(struct iscsi_conn *conn)
 
 restart:
 	msg = &conn->read_msg;
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(3, 19, 0)
+	read_size = msg->msg_iter.count;
+#else
 	read_size = conn->read_size;
+#endif
 
 	oldfs = get_fs();
 	set_fs(get_ds());
@@ -706,8 +715,13 @@ restart:
 			   MSG_DONTWAIT | MSG_NOSIGNAL);
 	set_fs(oldfs);
 
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(3, 19, 0)
+	TRACE_DBG("nr_segs %zd, bytes_left %zd, res %d",
+		  msg->msg_iter.nr_segs, msg->msg_iter.count, res);
+#else
 	TRACE_DBG("msg_iovlen %zd, read_size %d, res %d", msg->msg_iovlen,
 		  read_size, res);
+#endif
 
 	if (res > 0) {
 		/*
@@ -715,9 +729,14 @@ restart:
 		 * msg->msg_iov and msg->msg_iovlen. The BUG_ON() statement
 		 * below verifies this.
 		 */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(3, 19, 0)
+		sBUG_ON(msg->msg_iter.count + res != read_size);
+		res = msg->msg_iter.count;
+#else
 		/* To do: restore msg->msg_iov check. */
 		conn->read_size -= res;
 		res = conn->read_size;
+#endif
 	} else {
 		switch (res) {
 		case -EAGAIN:
@@ -896,7 +915,11 @@ static int process_read_io(struct iscsi_conn *conn, int *closed)
 			break;
 
 		case RX_END:
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(3, 19, 0)
+			bytes_left = conn->read_msg.msg_iter.count;
+#else
 			bytes_left = conn->read_size;
+#endif
 			if (unlikely(bytes_left != 0)) {
 				PRINT_CRIT_ERROR("conn read_size !=0 on RX_END "
 					"(conn %p, op %x, read_size %d)", conn,
@@ -908,7 +931,11 @@ static int process_read_io(struct iscsi_conn *conn, int *closed)
 
 			cmnd_rx_end(cmnd);
 
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(3, 19, 0)
+			EXTRACHECKS_BUG_ON(conn->read_msg.msg_iter.count != 0);
+#else
 			EXTRACHECKS_BUG_ON(conn->read_size != 0);
+#endif
 
 			/*
 			 * To maintain fairness. Res must be 0 here anyway, the