Indeed this issue started after upgrading to 4.10.0-26-generic. We've been using 4.8.0-34-generic previously, and didn't see that issue there.
The hio driver is not present upstream, it's been included in xenial with Bug #1603483.
Also, we've had consistency issues with this driver before (cf. Bug #1646643), but afaics the patches from that bug are included in 4.10.0-26-generic
Indeed this issue started after upgrading to 4.10.0-26-generic. We've been using 4.8.0-34-generic previously, and didn't see that issue there.
The hio driver is not present upstream, it's been included in xenial with Bug #1603483.
Also, we've had consistency issues with this driver before (cf. Bug #1646643), but afaics the patches from that bug are included in 4.10.0-26-generic