On Wed, Feb 21, 2024 at 05:19:54PM +0100, Jan Kara wrote: > > No. Cases like above are the reason why there's still a config option > CONFIG_BLK_DEV_WRITE_MOUNTED and it defaults to 'y'. We need to be fixing > userspace - util-linux in this case - to avoid having writeable file handle > open to block devices that are being mounted. Note also that at least as far as ext4 is concerned, I don't recommend that people use CONFIG_BLK_DEV_WRITE_MOUNTED on production systems. This will break programs like tune2fs operating on mounted file systems. There is a plan to add super to allow various superblock tuning operations to bet set via ioctls, much like the new ioctl's which allow the label and uuid to be set via an ioctl. This will require users upgrade to newer kerrnels and newer versions of e2fsprogs, so it will a while before we're at that point. For now, the main use of CONFIG_BLK_DEV_WRITE_MOUNTED is to prevent tools like syzbot from issuing false positives; I don't recommend that it be used in other situations. Cheers, - Ted
