Merged three years ago in Linux 5.12 was [1]IDMAPPED mounts for new use-cases from containers to systemd-homed . IDMAPPED mounts allow for different mounts to expose the same file or directory with different ownership such as for sharing files between multiple users or multiple systems. With time all of the major Linux file-systems have seen support added for [2]IDMAPPED mounts while for Linux 6.12 support is on the way for FUSE file-systems.

File-Systems in User-Space are seeing infrastructure added to the common FUSE code for being able to support IDMAPPED mounts. Plus the initial FUSE file-system making use of this code is VirtIO-FS. The VirtIO-FS file-system can optionally now use IDMAPPED mounts and there is also the code pending for [3]VirtIOFSD for supporting it.

The VirtIO-FS support and the FUSE IDMAPPED infrastructure was queued this week into fuse.git's [4]for-next branch ahead of the Linux 6.12 merge window opening in the next week or two. So barring any last minute issues or objections from Linus Torvalds, FUSE should be able to support IDMAPPED mounts with Linux 6.12.



[1] https://www.phoronix.com/news/IDMAPPED-Mounts-Linux-5.12

[2] https://www.phoronix.com/search/idmapped

[3] https://gitlab.com/virtio-fs/virtiofsd/-/merge_requests/245

[4] https://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse.git/log/?h=for-next