Re: zfs panic in zfs:vdev_disk_open.part.4

[Yorick Hardy <yorickhardy%gmail.com@localhost>]

Dear Juergen,

On 2020-11-28, J. Hannken-Illjes wrote:
> > On 24. Nov 2020, at 19:16, Yorick Hardy <yorickhardy%gmail.com@localhost> wrote:
> > 
> > Dear David,
> > 
> > On 2020-11-24, Yorick Hardy wrote:
> >> Dear David,
> >> 
> >> On 2020-11-22, David Brownlee wrote:
> >>> I'm seeing a (new?) panic on netbsd-9 with zfs. It seems to trigger
> >>> when a newly created zfs pool attempts to be mounted:
> >>> 
> >>> panic: vrelel: bad ref count
> >>> cpu0: Begin traceback...
> >>> vpanic() at netbsd:vpanic+0x160
> >>> vcache_reclaim() at netbsd:vcache_reclaim
> >>> vrelel() at netbsd:vrelel+0x22e
> >>> vdev_disk_open.part.4() at zfs:vdev_disk_open.part.4+0x44e
> >>> vdev_open() at zfs:vdev_open+0x9e
> >>> vdev_open_children() at zfs:vdev_open_children+0x39
> >>> vdev_root_open() at zfs:vdev_root_open+0x33
> >>> vdev_open() at zfs:vdev_open+0x9e
> >>> vdev_create() at zfs:vdev_create+0x1b
> >>> spa_create() at zfs:spa_create+0x28c
> >>> zfs_ioc_pool_create() at zfs:zfs_ioc_pool_create+0x19b
> >>> zfsdev_ioctl() at zfs:zfsdev_ioctl+0x265
> >>> nb_zfsdev_ioctl() at zfs:nb_zfsdev_ioctl+0x38
> >>> VOP_IOCTL() at netbsd:VOP_IOCTL+0x54
> >>> vn_ioctl() at netbsd:vn_ioctl+0xa5
> >>> sys_ioctl() at netbsd:sys_ioctl+0x5ab
> >>> syscall() at netbsd:syscall+0x157
> >>> --- syscall (number 54) ---
> >>> 7e047af6822a:
> >>> cpu0: End traceback...
> >>> 
> >>> Anyone seeing anything similar (I continue to have a bunch of other
> >>> boxes which use zfs without issue)
> >>> 
> >>> David
> >> 
> >> I don't know if it helps, but it looks like vn_close(vp,..) should be called instead
> >> of vrele(vp) at
> >> 
> >> https://nxr.netbsd.org/xref/external/cddl/osnet/dist/uts/common/fs/zfs/vdev_disk.c#218
> >> 
> >> and
> >> 
> >> https://nxr.netbsd.org/xref/external/cddl/osnet/dist/uts/common/fs/zfs/vdev_disk.c#250
> > 
> > Unless I am mistaken, I think you are hitting the error path which
> > should probably call vn_close as below. My machine is a bit old, so
> > I have not even compile tested yet and there is still the question
> > of why/if you are in the error path.
> > 
> > If it does not help, apologies in advance!
> > 
> > --
> > Kind regards,
> > 
> > Yorick Hardy
> > 
> > Index: external/cddl/osnet/dist/uts/common/fs/zfs/vdev_disk.c
> > ===================================================================
> > RCS file: /cvsroot/src/external/cddl/osnet/dist/uts/common/fs/zfs/vdev_disk.c,v
> > retrieving revision 1.18
> > diff -u -r1.18 vdev_disk.c
> > --- src/external/cddl/osnet/dist/uts/common/fs/zfs/vdev_disk.c	25 Jun 2020 09:39:15 -0000	1.18
> > +++ src/external/cddl/osnet/dist/uts/common/fs/zfs/vdev_disk.c	24 Nov 2020 18:10:07 -0000
> > @@ -215,7 +215,8 @@
> > 		return (SET_ERROR(error));
> > 	}
> > 	if (vp->v_type != VBLK) {
> > -		vrele(vp);
> > +		/* VN_RELE(vp); ?? */
> > +		vn_close(vp, FREAD|FWRITE, kcred);
> > 		vd->vdev_stat.vs_aux = VDEV_AUX_OPEN_FAILED;
> > 		return (SET_ERROR(EINVAL));
> > 	}
> > @@ -247,7 +248,8 @@
> > 	error = workqueue_create(&dvd->vd_wq, "vdevsync",
> > 	    vdev_disk_flush, dvd, PRI_NONE, IPL_NONE, WQ_MPSAFE);
> > 	if (error != 0) {
> > -		vrele(vp);
> > +		/* VN_RELE(vp); ?? */
> > +		vn_close(vp, FREAD|FWRITE, kcred);
> > 		return (SET_ERROR(error));
> > 	}
> 
> Good catch Yorick, though I prefer the attached diff.
> Pleasae commit and request pullup to -9.
> 
> --
> J. Hannken-Illjes - hannken%eis.cs.tu-bs.de@localhost - TU Braunschweig

Of course! I had a slight disaster with my CVS checkout, I will commit
and request a pullup it once I have completed a new checkout.

-- 
Kind regards,

Yorick Hardy