libceph: init the cursor when preparing sparse read in msgr2

[ Upstream commit 321e3c3 ]

The cursor is no longer initialized in the OSD client, causing the
sparse read state machine to fall into an infinite loop.  The cursor
should be initialized in IN_S_PREPARE_SPARSE_DATA state.

[ idryomov: use msg instead of con->in_msg, changelog ]

Link: https://tracker.ceph.com/issues/64607
Fixes: 8e46a2d ("libceph: just wait for more data to be available on the socket")
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Tested-by: Luis Henriques <lhenriques@suse.de>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: lxbsz

net/ceph/messenger_v2.c

@@ -2038,6 +2038,9 @@ static int prepare_sparse_read_data(struct ceph_connection *con)
 	if (!con_secure(con))
 		con->in_data_crc = -1;
 
+	ceph_msg_data_cursor_init(&con->v2.in_cursor, msg,
+				  msg->sparse_read_total);
+
 	reset_in_kvecs(con);
 	con->v2.in_state = IN_S_PREPARE_SPARSE_DATA_CONT;
 	con->v2.data_len_remain = data_len(msg);