Bezüglich Rick Macklem's Nachricht vom 07.08.2016 23:34 (localtime): > Harry Schmalzbauer wrote: >> Hello, >> >> I had another crash which I'm quite sure was triggered by mount_unionfs: > Just in case you are not already aware, unionfs is always broken. Read > the BUGS > section at the end of "man mount_unionfs". If it were easy to fix, > someone would > have done so long ago. Yes, some use it successfully, but if not... > > Sorry, but I suspect that is how it will remain, rick
Thanks for the hint, not happy to hear that, but I was not aware of that explicit warning in man 8 mount_unionfs :-( This feature is utterly important for me (all my productive machines have "/" read-only mounted and "/etc" is an union to a writable, synch mounted separate fs), so back in 2012, after a lot of locking redesign has been done in 9-current, I got Attilio Raos attention and he gave out some test patches for 9.0. He was aware of missing locking adjustments, but patches addressing the majority of them didn't work. Since then I'm draging a minimal patch which prevents at least the kernel panics for me. Unfortunately I don't have the skills to continue Attilio Raos work. Just for anybody else needing unionfs: https://people.freebsd.org/~attilio/unionfs_missing_insmntque_lock.patch This patch still applies and I'm successfully using this (unmodified) up to FreeBSD-10.3 and never had any panic in all these years. I will continue using it for FreeBSD-11 and I guess it will also prevent my last reported panics. But I wanted to take part in the BETA test without local modifications at first. Another very importend usage scenario of unionfs for me is for my build host(s). I'm (nfs4-)sharing a svn-checked out read-only portstree. My inofficial "ports/inofficial" directory perfectly shows up by unionfs-mounting it below the unaltered portstree :-) For me, unionfs is as important as ZFS (and nullfs) is in FreeBSD. First thing to do for me, after I won in lottery, was to find someone who can be sponsored fixing unionfs ;-) And bringing MNAMELEN into 21st century state, matching ZFS needs: https://lists.freebsd.org/pipermail/freebsd-hackers/2015-November/048640.html This is another patch I'm carrying for a very long time which solves tremendous limitations for me. Without that, I couldn't use ZFS snapshots in real world, along with a human-friendly dataset naming :-) -Harry _______________________________________________ freebsd-stable@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"
