Date: Sun, 25 Oct 2009 16:00:18 GMT From: Carl Chave <carl@chave.us> To: freebsd-fs@FreeBSD.org Subject: Re: kern/139806: [zfs] [panic] Write attempt to file in ZFS snapshot dir causes panic Message-ID: <200910251600.n9PG0IeL019956@freefall.freebsd.org>
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The following reply was made to PR kern/139806; it has been noted by GNATS.
From: Carl Chave <carl@chave.us>
To: bug-followup@FreeBSD.org
Cc:
Subject: Re: kern/139806: [zfs] [panic] Write attempt to file in ZFS snapshot
dir causes panic
Date: Sun, 25 Oct 2009 10:47:40 -0400
Rebuilt zfs.ko using:
head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c
(version 197861 + this patch)
head/sys/cddl/compat/opensolaris/kern/opensolaris_policy.c (version 197861)
head/sys/cddl/compat/opensolaris/sys/policy.h (version 197861)
Resulting zfs.ko works as expected and does not panic when attempting
to modify an existing snapshot file as described in the original PR.
On Thu, Oct 22, 2009 at 3:50 PM, Jaakko Heinonen <jh@freebsd.org> wrote:
>
> Hi,
>
> On 2009-10-21, Carl Chave wrote:
>> Fixit# echo hello >> test.txt
>> panic: dirtying snapshot!
>
> The problem seems to be that in certain conditions zfs_freebsd_access()
> uses only vaccess(9) for access check. However vaccess(9) doesn't handle
> the read-only file system case.
>
> Could you try this patch?
>
> --- patch begins here ---
> Index: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> --- sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c =A0(revisi=
on 198368)
> +++ sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c =A0(workin=
g copy)
> @@ -3989,7 +3989,12 @@
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0struct thread *a_td;
> =A0 =A0 =A0 =A0} */ *ap;
> =A0{
> + =A0 =A0 =A0 int error;
>
> + =A0 =A0 =A0 error =3D zfs_access(ap->a_vp, ap->a_accmode, 0, ap->a_cred=
, NULL);
> + =A0 =A0 =A0 if (error !=3D 0)
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 return (error);
> +
> =A0 =A0 =A0 =A0/*
> =A0 =A0 =A0 =A0 * ZFS itself only knowns about VREAD, VWRITE and VEXEC, t=
he rest
> =A0 =A0 =A0 =A0 * we have to handle by calling vaccess().
> @@ -3999,11 +4004,11 @@
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0znode_t *zp =3D VTOZ(vp);
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0znode_phys_t *zphys =3D zp->z_phys;
>
> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 return (vaccess(vp->v_type, zphys->zp_mode,=
zphys->zp_uid,
> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 zphys->zp_gid, ap->a_accmode, ap->a=
_cred, NULL));
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 error =3D vaccess(vp->v_type, zphys->zp_mod=
e, zphys->zp_uid,
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 zphys->zp_gid, ap->a_accmode, ap->a=
_cred, NULL);
> =A0 =A0 =A0 =A0}
>
> - =A0 =A0 =A0 return (zfs_access(ap->a_vp, ap->a_accmode, 0, ap->a_cred, =
NULL));
> + =A0 =A0 =A0 return (error);
> =A0}
>
> =A0static int
> --- patch ends here ---
>
> --
> Jaakko
>
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