Date: Tue, 09 Aug 2016 11:47:44 +0200 From: Harry Schmalzbauer <freebsd@omnilan.de> To: Mark Johnston <markj@freebsd.org> Cc: Rick Macklem <rmacklem@uoguelph.ca>, FreeBSD Stable <freebsd-stable@freebsd.org> Subject: Re: unionfs bugs, a partial patch and some comments [Was: Re: 1-BETA3 Panic: __lockmgr_args: downgrade a recursed lockmgr nfs @ /usr/local/share/deploy-tools/RELENG_11/src/sys/fs/unionfs/union_vnops.c:1905] Message-ID: <57A9A6C0.9060609@omnilan.de> In-Reply-To: <20160809060213.GA67664@raichu> References: <57A79E24.8000100@omnilan.de> <YQBPR01MB0401201977AEA8A803F27B23DD1A0@YQBPR01MB0401.CANPRD01.PROD.OUTLOOK.COM> <57A83C78.1070403@omnilan.de> <20160809060213.GA67664@raichu>
next in thread | previous in thread | raw e-mail | index | archive | help
Bezüglich Mark Johnston's Nachricht vom 09.08.2016 08:02 (localtime): … >> >> 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. > > Having spent some time looking at unionfs, I'm a bit skeptical that this > patch will address the panic you reported earlier, though I'd be > interested to know if it does. Thanks for your attention. I can confirm that it has prevented panics for more than 4 years (9.0-10.3) and it seems to be still "good enough" to also prevent panics in 11-BETA4. I updated my build host (stable/11, this time with the unionfs_missing_insmntque_lock.patch), where the recent panics happened and unionfs gets much more utilized than usually in my setups: No panic with that patch anymore. Just one message like "prevented resource deadlock" occured. > Reading the code, I think it will just > address an INVARIANTS-only assertion in insmntque1(). > > Unfortunately, unionfs is quite difficult to fix within the current > constraints of FreeBSD's VFS. unionfs_readdir() is a particularly good > demonstration of this fact: some callers of VOP_READDIR expect the > cookies returned by the FS to be monotonically increasing, but unionfs > has no straightforward way to make this guarantee. I'm sorry, I can't provide help here. My skills would require a huge ammount of lerning-time to get into that matter. I'd love to do that, but I can't afford :-( Thanks, -Harry
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?57A9A6C0.9060609>