BugLink: https://bugs.launchpad.net/bugs/1818797

commit 89d13c38 upstream.

This patch fixes missing up_read call.

Fixes: c9b60788 ("f2fs: fix to do sanity check with block address in main area")
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>