On Thu 06-07-23 08:55:18, Christoph Hellwig wrote: > 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. Well, this is exactly what this patch does - we use dev_t to lookup the superblock in sget_fc() and we open the block device only if we cannot find matching superblock and need to create a new one... Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
