On Tue, Jul 04, 2023 at 02:56:54PM +0200, Jan Kara wrote: > When we don't allow opening of mounted block devices for writing, bind > mounting is broken because the bind mount tries to open the block device > before finding the superblock for it already exists. Reorganize the > mounting code to first look whether the superblock for a particular > device is already mounted and open the block device only if it is not. Warning: this might be a rathole. I really hate how mount_bdev / get_tree_bdev try to deal with multiple mounts. The idea to just open the device and work from there just feels very bogus. There is really no good reason to have the bdev to find a superblock, the dev_t does just fine (and in fact I have a patch to remove the bdev based get_super and just use the dev_t based one all the time). So I'd really like to actually turn this around and only open when we need to allocate a new super block. That probably means tearning sget_fc apart a bit, so it will turn into a fair amount of work, but I think it's the right thing to do.
