On Wed, Nov 08, 2023 at 05:20:06PM +0100, Christian Brauner wrote: > This would also allow tools that want to to detect when they're crossing > into a new subvolume - be it on btrfs or bcachefs - and take appropriate > measures deciding what they want to do just relying on statx() without > any additional system calls. How? If they want to only rely on Posix and not just he historical unix/linux behavior they need to compare st_dev for the inode and it's parent to see if it the Posix concept of a mount point (not to be confused with the Linux concept of a mountpoint apparently) because that allows the file system to use a new inode number namespace.
