nginx redirect all directories except one

location / {
    rewrite ^/(.*)$ http://www.google.com/search?q=$1 permanent;
}

location /blog {
      root   html;
      index index.php;
      try_files $uri $uri/ /blog/index.php;
}

• http://nginx.org/r/location
• http://nginx.org/en/docs/http/request_processing.html