Date: Sun, 27 Jul 2014 20:24:13 +0200 From: Harald Schmalzbauer <h.schmalzbauer@omnilan.de> To: Konstantin Belousov <kostikbel@gmail.com> Cc: FreeBSD Stable <freebsd-stable@freebsd.org> Subject: Re: panic/lock on 9.3-RELEASE with nullfs/nfs/zfs combination Message-ID: <53D543CD.5070607@omnilan.de> In-Reply-To: <20140727174757.GN93733@kib.kiev.ua> References: <53D12973.3010805@omnilan.de> <20140724165917.GT93733@kib.kiev.ua> <53D1503B.2030200@omnilan.de> <20140724193048.GU93733@kib.kiev.ua> <53D2006C.7090207@omnilan.de> <20140725151448.GY93733@kib.kiev.ua> <53D380B2.2080700@omnilan.de> <20140726114839.GF93733@kib.kiev.ua> <53D5105A.6040204@omnilan.de> <20140727174757.GN93733@kib.kiev.ua>
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Bez=FCglich Konstantin Belousov's Nachricht vom 27.07.2014 19:47
(localtime):
> On Sun, Jul 27, 2014 at 04:44:42PM +0200, Harald Schmalzbauer wrote:
>> Bez??glich Konstantin Belousov's Nachricht vom 26.07.2014 13:48
>> (localtime):
>> I can't emphasize how much I hate my lousy C skills... Got "format '%#=
x'
>> expects type 'unsigned int', but argument 3 has type 'u_long'
>> [-Wformat]" from the compiler and found out that I can't read/understa=
nd
>> any part of your patch; not even the syntax :-(
>>
>> After reading printf(3) I change the 3rd additional line into
>> '("ldvp %p fl %#lx dvp %p fl %#lx flags %#x", ldvp, ldvp->v_vflag,'
>> ??? A blind man may sometimes hit the mark.
> This is because the patch was against HEAD, where I changed type of fla=
gs
> to not waste space. It was not merged to stable/9 to keep KBI.
>
>> Here's the panic:
>> panic: ldvp 0xfffffe001bafb000 fl 0x1 dvp 0xfffffe01b4e5a9d8 fl 0 flag=
s
>> 0x120e144
>> vnode vnode 0xfffffe014bc03dc8: 0xfffffe014bc03dc8: tag null, type VDI=
R
>> tag null, type VDIR
>> usecount 1, writecount 0, refcount 1 mountedhere 0
>> usecount 1, writecount 0, refcount 1 mountedhere 0
>> flags (VV_ROOT|VI_ACTIVE)
>> flags (VV_ROOT|VI_ACTIVE)
>> v_object 0xfffffe014bbf4828 ref 0 pages 0 cleanbuf 0 dirtybuf 0
>> v_object 0xfffffe014bbf4828 ref 0 pages 0 cleanbuf 0 dirtybuf 0
>> lock type zfs: SHARED (count 1)
>> lock type zfs: SHARED (count 1)
>> vp=3D0xfffffe014bc03dc8, lowervp=3D0xfffffe001bafb000
>> vp=3D0xfffffe014bc03dc8, lowervp=3D0xfffffe001bafb000
> So the root vnode for underlying ZFS filesystem somehow managed to get
> two different upper vnodes for nullfs mount. My guess is that the real=
> problem is due to inconsistent initialization of v_hash for zfs vnodes.=
> It only get set in zfs_vget(), which causes root vnode to have zero
> hash initially.
>
> Please, keep the KASSERT() patch applied, revert the VV_ROOT patch for
> nullfs, and apply the following change. Then retest.
>
> diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.=
c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.c
> index 04160c6..33748fe 100644
> --- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.c
> +++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.c
> @@ -2075,8 +2075,6 @@ zfs_vget(vfs_t *vfsp, ino_t ino, int flags, vnode=
_t **vpp)
> err =3D vn_lock(*vpp, flags);
> if (err !=3D 0)
> *vpp =3D NULL;
> - else
> - (*vpp)->v_hash =3D ino;
> return (err);
> }
> =20
> diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_znode.c=
b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_znode.c
> index ac55996..c8f86b8 100644
> --- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_znode.c
> +++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_znode.c
> @@ -1228,9 +1228,10 @@ again:
> vnode_t *vp =3D ZTOV(zp);
> =20
> err =3D insmntque(vp, zfsvfs->z_vfs);
> - if (err =3D=3D 0)
> + if (err =3D=3D 0) {
> + vp->v_hash =3D obj_num;
> VOP_UNLOCK(vp, 0);
> - else {
> + } else {
> zp->z_vnode =3D NULL;
> zfs_znode_dmu_fini(zp);
> zfs_znode_free(zp);
Applyed these two patches along with the KASSERT patch (reverted
ROOT_VV) and did the same simple test: No panic, no debug message. So
this also fixes my limited and simple test case.
Tell me if I can provide anything else, I'll keep that latest patched
version running, tomorrow will be regular usage and I'll report again.
Thanks,
-Harry
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