repeatable ZFS panic: share->excl

[John Baldwin]

John Baldwin wrote:
> Attilio Rao wrote:
>> 2009/3/13, John Baldwin <john at baldwin.cx>:
>>> This is similar to the patch I've asked lulf@ to test except that it 
>>> is longer and I fix a bug where zfs_lookup() can leak a vnode lock if 
>>> the access check fails. :-)  The last one I sent to lulf@ is at 
>>> www.FreeBSD.org/~jhb/patches/zfs_ea.patch.
>>
>> I really thought zfs_lookup() was returning the lock held as a feature 
>> assming no LOCKLEAF. Is that a bug instead?
> 
> 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_dir.c
> +++
> /Users/jhb/work/p4/lock/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_dir.c 
> 
> @@ -940,6 +940,7 @@
>          /* 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@ reports success with this patch.  Pawel, can you review it?

-- 
John Baldwin