fix "direction" argument of iov_iter_kvec()

stable inclusion
from stable-v5.10.168
commit 63d1c4edbfc1e93f40170bbee7965ca55973cd12
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7URR4

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=63d1c4edbfc1e93f40170bbee7965ca55973cd12

----------------------------------------------------

[ Upstream commit fc02f337 ]
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: Nzhaoxiaoqiang11 <zhaoxiaoqiang11@jd.com>

drivers/xen/pvcalls-back.c

@@ -129,13 +129,13 @@ static bool pvcalls_conn_back_read(void *opaque)
 	if (masked_prod < masked_cons) {
 		vec[0].iov_base = data->in + masked_prod;
 		vec[0].iov_len = wanted;
-		iov_iter_kvec(&msg.msg_iter, WRITE, vec, 1, wanted);
+		iov_iter_kvec(&msg.msg_iter, READ, vec, 1, wanted);
 	} else {
 		vec[0].iov_base = data->in + masked_prod;
 		vec[0].iov_len = array_size - masked_prod;
 		vec[1].iov_base = data->in;
 		vec[1].iov_len = wanted - vec[0].iov_len;
-		iov_iter_kvec(&msg.msg_iter, WRITE, vec, 2, wanted);
+		iov_iter_kvec(&msg.msg_iter, READ, vec, 2, wanted);
 	}
 
 	atomic_set(&map->read, 0);
@@ -188,13 +188,13 @@ static bool pvcalls_conn_back_write(struct sock_mapping *map)
 	if (pvcalls_mask(prod, array_size) > pvcalls_mask(cons, array_size)) {
 		vec[0].iov_base = data->out + pvcalls_mask(cons, array_size);
 		vec[0].iov_len = size;
-		iov_iter_kvec(&msg.msg_iter, READ, vec, 1, size);
+		iov_iter_kvec(&msg.msg_iter, WRITE, vec, 1, size);
 	} else {
 		vec[0].iov_base = data->out + pvcalls_mask(cons, array_size);
 		vec[0].iov_len = array_size - pvcalls_mask(cons, array_size);
 		vec[1].iov_base = data->out;
 		vec[1].iov_len = size - vec[0].iov_len;
-		iov_iter_kvec(&msg.msg_iter, READ, vec, 2, size);
+		iov_iter_kvec(&msg.msg_iter, WRITE, vec, 2, size);
 	}
 
 	atomic_set(&map->write, 0);