iov_iter: Separate type from direction and use accessor functions

In the iov_iter struct, separate the iterator type from the iterator
direction and use accessor functions to access them in most places.

Convert a bunch of places to use switch-statements to access them rather
then chains of bitwise-AND statements.  This makes it easier to add further
iterator types.  Also, this can be more efficient as to implement a switch
of small contiguous integers, the compiler can use ~50% fewer compare
instructions than it has to use bitwise-and instructions.

Further, cease passing the iterator type into the iterator setup function.
The iterator function can set that itself.  Only the direction is required.

Signed-off-by: David Howells <dhowells@redhat.com>

2 files changed, 5 insertions, 7 deletions

diff --git a/drivers/target/iscsi/iscsi_target_util.c b/drivers/target/iscsi/iscsi_target_util.c
index 49be1e41290c..991482576417 100644
--- a/drivers/target/iscsi/iscsi_target_util.c
+++ b/drivers/target/iscsi/iscsi_target_util.c
@@ -1258,8 +1258,7 @@ static int iscsit_do_rx_data(
 		return -1;
 
 	memset(&msg, 0, sizeof(struct msghdr));
-	iov_iter_kvec(&msg.msg_iter, READ | ITER_KVEC,
-		      count->iov, count->iov_count, data);
+	iov_iter_kvec(&msg.msg_iter, READ, count->iov, count->iov_count, data);
 
 	while (msg_data_left(&msg)) {
 		rx_loop = sock_recvmsg(conn->sock, &msg, MSG_WAITALL);
@@ -1315,8 +1314,7 @@ int tx_data(
 
 	memset(&msg, 0, sizeof(struct msghdr));
 
-	iov_iter_kvec(&msg.msg_iter, WRITE | ITER_KVEC,
-		      iov, iov_count, data);
+	iov_iter_kvec(&msg.msg_iter, WRITE, iov, iov_count, data);
 
 	while (msg_data_left(&msg)) {
 		int tx_loop = sock_sendmsg(conn->sock, &msg);
diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c
index 16751ae55d7b..49b110d1b972 100644
--- a/drivers/target/target_core_file.c
+++ b/drivers/target/target_core_file.c
@@ -303,7 +303,7 @@ fd_execute_rw_aio(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
 		len += sg->length;
 	}
 
-	iov_iter_bvec(&iter, ITER_BVEC | is_write, bvec, sgl_nents, len);
+	iov_iter_bvec(&iter, is_write, bvec, sgl_nents, len);
 
 	aio_cmd->cmd = cmd;
 	aio_cmd->len = len;
@@ -353,7 +353,7 @@ static int fd_do_rw(struct se_cmd *cmd, struct file *fd,
 		len += sg->length;
 	}
 
-	iov_iter_bvec(&iter, ITER_BVEC, bvec, sgl_nents, len);
+	iov_iter_bvec(&iter, READ, bvec, sgl_nents, len);
 	if (is_write)
 		ret = vfs_iter_write(fd, &iter, &pos, 0);
 	else
@@ -490,7 +490,7 @@ fd_execute_write_same(struct se_cmd *cmd)
 		len += se_dev->dev_attrib.block_size;
 	}
 
-	iov_iter_bvec(&iter, ITER_BVEC, bvec, nolb, len);
+	iov_iter_bvec(&iter, READ, bvec, nolb, len);
 	ret = vfs_iter_write(fd_dev->fd_file, &iter, &pos, 0);
 
 	kfree(bvec);