Increase file upload size limit in PHP-Nginx

1. Technically,  post_max_size should always be larger than upload_max_filesize but for large numbers like 100M you can safely make them equal.
2. There is another variable max_input_time which can limit upload size but I have never seen it creating any issue. If your application supports uploads of file-size in GBs, you may need to adjust it accordingly. I am using PHP-FPM behind Nginx from very long time and I think in such kind of setup, its Nginx to which a client uploads file and then Nginx copies it to PHP. As Nginx to PHP copying will be local operation max_input_time may never create issue. I also believe Nginx may not copy the file but merely hand-over the location of file or descriptor records to PHP!

Add following line to http{..} block in nginx config:

http {
	#...
        client_max_body_size 100m;
	#...
}