Re: repeatable ZFS panic: share->excl

From: John Nielsen <lists_at_jnielsen.net>
Date: Fri, 20 Mar 2009 11:12:46 -0400
On Wednesday 18 March 2009 12:09:18 pm John Baldwin wrote:
> On Tuesday 17 March 2009 3:04:40 am Pawel Jakub Dawidek wrote:
> > On Fri, Mar 13, 2009 at 02:08:03PM -0400, John Baldwin wrote:
> > > John Baldwin wrote:
> > > >Yes, I think that is the real bug.  Looking at this further I
> > > > think zfs_get_xattrdir() will return the vnode locked if it has
> > > > to create a new node via zfs_make_attrdir() but only returns it
> > > > held and unlocked if it finds an existing one.  So my new patch
> > > > is to just fix zfs_get_xattrdir() to unlock the vnode if it
> > > > creates a new one like so:
> > > >
> > > >(Sorry, TBird is probably going to butcher all the whitespace):
> > > >
> > > >---
> >
> >//depot/user/jhb/lock/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_d
> >ir.c
> >
> > > >+++
> >
> >/Users/jhb/work/p4/lock/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs
> >_dir.c
> >
> > > >_at__at_ -940,6 +940,7 _at__at_
> > > >         /* NB: we already did dmu_tx_wait() if necessary */
> > > >         goto top;
> > > >     }
> > > >+    VOP_UNLOCK(*xvpp, 0);
> > > >
> > > >     return (error);
> > > > }
> > > >
> > > >A non-butchered version is at
> > > > www.FreeBSD.org/~jhb/patches/zfs_ea.patch.
> > >
> > > So lulf_at_ reports success with this patch.  Pawel, can you review
> > > it?
> >
> > Yes, it works for me too and looks good. The only thing we need to
> > change is to check for error beeing 0 before unlocking the vnode.
> > The zfs_make_xattrdir() function can still return with EIO, so I'd
> > add something like this:
> >
> > 	if (error == 0)
> > 		VOP_UNLOCK(*xvpp, 0);
>
> Yes, I realized this about 30 minutes after I sent this e-mail. :-P  I
> will commit a version with the error check today.
>
> > Thank you John for spending time on tracking this one down.
>
> Sure, was good to read a bit of the ZFS code.

I had a chance to test this patch today and it looks good. Which is to say 
my system hasn't hung yet. :)

I built world from 3/19 -HEAD and was able to "lsextattr -h user" on files 
on a ZFS without any ill effects. I un-patched libarchive (so it uses 
extended attributes again) and rebuilt and reinstalled it and bsdtar and 
was able to do portupgrades normally.

Thanks to all involved.

JN
Received on Fri Mar 20 2009 - 14:13:15 UTC

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