On Wed, Nov 08, 2023 at 12:12:36AM -0800, Christoph Hellwig wrote: > On Wed, Nov 08, 2023 at 09:09:10AM +0100, Christian Brauner wrote: > > > a bind mount can of course change the dev_t - if it points to a > > > different super block at the moment. > > > > No, a bind mount just takes an existing directory tree of an existing > > filesystem and makes it visible on some location in the filesystem > > hierarchy. It doesn't change the device number it will inherit it from > > the superblock it belongs. > > That's what I'm trying to say. > > So if you have: > > /mnt/1/ with dev 8 > /mnt/2/ with dev 23 > > then a bind mount of > > /mnt/1/foo to /mnt/2/bar will get your dev 8 for /mnt/2/bar > > So the device number changes at the mount point here, bind mount or not. Yes, I know. But /mnt/2/ will have the device number of the superblock/filesystem it belongs to and so will /mnt/1. Creating a bind-mount won't suddenly change the device number and decoupling it from the superblock it is a bind-mount of.
