This repo provides scripts to install the (Linux) kernel module shiftfs via dkms.
| This Repository: | Upstream development: |
|---|---|
| Mostly inactive at the moment | active |
shiftfs is a kernel filesystem for the Linux kernel.
It provides easier uid/gid-shifting for containers and can be used for example with Incus and LXD (see also: Usecases).
shiftfs was made by:
See Credits
Further information on shiftfs can be found in the Ubuntu kernel repos (see Overview of Branches/Versions below for specific links) and in the official Linuxcontainers.org Forum (the following link might be outdated, it was the original announcement): https://discuss.linuxcontainers.org/t/trying-out-shiftfs/5155
The official successor of shiftfs is available now.
The new approach called "idmapped mounts" is natively included in recent Linux kernels (since kernel version 5.12) - so there is no need for dkms-modules anymore.
Support for the new approach is implemented in Incus and LXD (since version 4.16) and the transition is seamless, so Incus and LXD will automatically switch to the new approach, if available, and all commands/options stay the same.
Update: The following filesystems are now supported as underlying filesystems for containers and volumes: ext4, xfs, vfat, btrfs (since kernel version 5.15), ZFS (recent kernels) and cephfs (recent kernels).
So the only reason to still use shiftfs is if you use older kernels, or have other specific reasons.
If you still need to use shiftfs, then the original shiftfs (the version used in this repo) is still available for:
See Overview of Branches/Versions below for more information on each available version in this repo.
Sources:
There are different versions of shiftfs.c for different kernel versions, so I cover a few of them:
| Branch/Version: | For Kernel(version): | Further Notes: |
|---|---|---|
| - | 6.3.x | I did not set up a branch yet, but you can try to replace the shiftfs.c file from k6.1 with this one. You also need to adjust dkms.conf. |
| k6.1 | 6.1.x and 6.2.x | Does not work with 6.0.x. Also take a look at the Notes! |
| k5.18 | 5.18.x, 5.19.x (and probably 6.0.x) | 5.19.x and 6.0.x are not tested. Kernel versions are deprecated upstream, see kernel.org. |
| k5.17 | 5.17.x | Kernel version is deprecated upstream, see kernel.org. |
| k5.16 | 5.15.x (longterm version) (and probably 5.16.x) | - |
| k5.13 | 5.13.x (and probably 5.14.x) | Kernel versions are deprecated upstream, see kernel.org. |
| k5.10 | 5.10.x (longterm version) and 5.8.x | - |
| k5.4 | 5.4 (longterm version) | - |
Other kernel versions that are newer than 5.x might work, but there is no guarantee and I will not provide that. You have the best chances if you search inside the Ubuntu kernel repos and might find a version that matches your kernel version (e.g. hirsute kernel repo - master next for 5.11).
shiftfs will most likely not work on kernels older than version 5.x. Thus the only recent and active branch newer than 5 is 5.4. See also kernel.org.
Regarding Overlayfs inside a container:
shiftfs can prevent the use of overlayfs inside a container.
A usecase for this is running Docker with the overlayfs-storage driver inside a lxd container.
A Kernelpatch that solves this is available, but it's not included in the mainline kernel (yet).
To my knowledge only Ubuntu included it (see solved bug report).
For workarounds and more information see: Issue 2 of this repo
More Issues may be found in the Ubuntu Kernel Bug Tracker.
If you want to post a testreport, take a look at: Testreports Issue on Github.
Incus: See my GitHub wiki and the Linuxcontainers Forum - Share Folders and Volumes
LXD (might be outdated): How to use shiftfs with LXD is described in my wiki
and in the official Forum of LXD: Usecases for shiftfs and Trying out shiftfs.
Report bugs first at: https://github.com/toby63/shiftfs-dkms/issues
shiftfs was made by:
(recent info is in the shiftfs.c file (See: footer -> tag: MODULE_AUTHOR))
Some files are based on the Debian package repo of bbswitch (https://salsa.debian.org/nvidia-team/bbswitch), including:
Special thanks to:
for the helpful advice.
General Public License, Version 2
See: LICENSE