Test for overlayfs will need --xino flag to work

[Cypresslin]

Hello,

we found that since commit 0787081 ("Add support for user defined mount options") the command to run overlayfs test is not working anymore, it will fail with:

Running './run --ov'
/mnt/a/foo100: File not on union layer
Environment variables:

***
*** ./run --ov --xino open-plain
***
TEST open-plain.py:10: Open O_RDONLY

With some further research I found the mount command has changed.
Compare with the previous working mount command from mount_union.py:

• Working (019085f "Relax layers check for older kernels"):
  mount -t overlay overlay /mnt -orw,
redirect_dir=on,xino=on,lowerdir=/lower,upperdir=/upper/0/u,workdir=/upper/0/w

• Not working (95be14e "Allow user provided options with or without -o")
  mount -t overlay overlay /mnt -orw,
redirect_dir=on -olowerdir=/lower,upperdir=/upper/0/u,workdir=/upper/0/w

It's missing xino=on, so it looks like you need the --xino flag to enable it, and indeed the cases can pass with this flag.

Is this an expected behaviour? (Maybe the README needs to be updated with --xino flag added to test command examples)
Thanks!

[amir73il]

Not expected, but I suspect you are testing with kernel prior to commit
926e94d79baf ("ovl: enable xino automatically in more cases")
and with kernel config
CONFIG_OVERLAY_FS_XINO_AUTO=y
Is that correct?

Please try this fix in run script after line 212:

if redirect_dir is False:
cfg.add_mntopt("redirect_dir=on")
redirect_dir = True

if xino:
cfg.add_mntopt("xino=on")

This will "upgrade" the default xino=auto to xino=on which happens already with kernel >= v5.7
Let me know if it works and I will add this to the code

[Cypresslin]

Hello,
you're right, it's an Ubuntu Focal 5.4 kernel (5.4.0-58-generic) without commit 926e94d79baf and with CONFIG_OVERLAY_FS_XINO_AUTO set to y

And this fix works.
Thank you!

[amir73il]

pushed the fix.
Added you as Reporter/Tester.
Thanks!