On Fri 07-07-23 09:39:05, Christian Brauner wrote: > On Thu, Jul 06, 2023 at 06:12:55PM +0200, Jan Kara wrote: > > 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... > > Can you do this rework independent of the bdev_handle work that you're > doing so this series doesn't depend on the other work and we can get > the VFS bits merged for this? Yeah, it should be doable. I'll have a look into it. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
