`fuse-overlayfs` provides rootless overlayfs functionality without depending
on any kernel patch.
Aside from rootless, `fuse-overlayfs` could be potentially used for eliminating
`chown()` calls that happen in userns-remap mode, because `fuse-overlayfs` also
provides shiftfs functionality.
System requirements:
* fuse-overlayfs needs to be installed. Tested with 0.7.6.
* kernel >= 4.18
Unit test: `go test -exec sudo -v ./daemon/graphdriver/fuse-overlayfs`
The implementation is based on Podman's `overlay` driver which supports
both kernel-mode overlayfs and fuse-overlayfs in the single driver instance:
https://github.com/containers/storage/blob/39a8d5ed/drivers/overlay/overlay.go
However, Moby's implementation aims to decouple `fuse-overlayfs` driver from the
kernel-mode driver (`overlay2`) for simplicity.
Fix#40218
Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>
Before this commit, overlay check was performed by looking for
`overlay` in /proc/filesystem. This obviously might not work
for rootless Docker (fs is there, but one can't use it as non-root).
This commit changes the check to perform the actual mount, by reusing
the code previously written to check for multiple lower dirs support.
The old check is removed from both drivers, as well as the additional
check for the multiple lower dirs support in overlay2 since it's now
a part of the main check.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
This moves supportsMultipleLowerDir() to overlayutils
so it can be used from both overlay and overlay2.
The only changes made were:
* replace logger with logrus
* don't use workDirName mergedDirName constants
* add mnt var to improve readability a bit
This is a preparation for the next commit.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
ext4 support d_type by default, but filetype feature is a tunable so
there is still a chance to disable it for some reasons. In this case,
print additional message to explicitly tell how to support d_type.
Signed-off-by: Chengguang Xu <cgxu519@gmx.com>
Support for running overlay/overlay2 on a backing filesystem
without d_type support (most likely: xfs, as ext4 supports
this by default), was deprecated for some time.
Running without d_type support is problematic, and can
lead to difficult to debug issues ("invalid argument" errors,
or unable to remove files from the container's filesystem).
This patch turns the warning that was previously printed
into an "unsupported" error, so that the overlay/overlay2
drivers are not automatically selected when detecting supported
storage drivers.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
