SLES12. We had a power outage yesterday, since then web sites are not loading images. In the error log:

AH00529: /srv/www/htdocs/sites/sitename/images/.htaccess pcfg_openfile: unable to check htaccess file, ensure it is readable and that '/srv/www/htdocs/sites/sitename/images/' is executable

How do you run a filesystem check on btrfs?