问题描述：
上传文件失败，文件大小4M左右。上传程序为Java，通过nginx反向代理写入Fastdfs中，但是一直失败，查看nginx错误日志，显示client intended to send too large body: 4134591 bytes。
根据错误信息提示，客户端发送的body过大，nginx默认的客户端body大小为1M。
官方文档如下：
Syntax: client_max_body_size size;
Default: client_max_body_size 1m;
Context: http, server, location
Sets the maximum allowed size of the client request body, specified in the “Content-Length” request header field. If the size in a request exceeds the configured value, the 413 (Request Entity Too Large) error is returned to the client. Please be aware that browsers cannot correctly display this error. Setting size to 0 disables checking of client request body size.
解决：
根据官方文档说明，可以在nginx配置文件中http、server、location等配置块添加配置，client_max_body_size size 100m;来调整允许的客户端上传文件的body大小。设置为0，表示不限制。
实例：
http {log_format main '$remote_addr - $remote_user [$time_local] "$request" ''$status $body_bytes_sent "$http_referer" ''"$http_user_agent" "$http_x_forwarded_for"';access_log /var/log/nginx/access.log main;sendfile on;tcp_nopush on;tcp_nodelay on;keepalive_timeout 65;types_hash_max_size 2048;client_max_body_size 100m;....}