zfs mount -a fails silently

[cruwe]

System information

Type	Version/Name
Distribution Name	Ubuntu
Distribution Version	17.04
Linux Kernel	4.10.0-35-generic #39-Ubuntu
Architecture	amd64
ZFS Version	0.6.5.9-2
SPL Version	0.6.5.9-1

Describe the problem you're observing

When calling zfs mount -a during or after boot, no dataset gets mounted, but zfs returns 0. With -v, no information pointing to the error condition is given. Calling zfs mount <some-ds> returns 0 and mounts the dataset. While ideally expecting the datasets to cleanly mount, I'd at least expect the program to return sth non-zero and preferably complaining loudly and calling me an idiot, should that be the case.

Describe how to reproduce the problem

cf. above. The problem appeared when upgrading and rebooting to/into 4.10.0-35-generic #39-Ubuntu, but have difficulties to fathom how that should have actually caused the issue. I have no further idea how to reproduce the issue, from my point of view, it appeared out of the blue.

I am happy to be of assistance providing additional data.

Include any warning/errors/backtraces from the system logs

This is an strace of a non-working zfs mount -a, that an strace of a working zfs mount <ds>.

[cruwe]

I have been reminded by colleagues to examine the canmount-property.

To my huge astonishment, about 80% of my datasets had the wrong canmount property, i.e. noauto instead of on.

Suspecting operator dementia, I examined my history ($HISTSIZE=10k), but according to my memory and history, I did not touch the canmount property since at least march.

I will close the issue and ask to be excused for the noise. Should anybody have an idea what could have caused this, I'd be happy to hear about it.