Re: repeatable ZFS panic: share->excl

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