Description Tim Bishop 2009-09-12 17:30:07 UTC

I'm running with a ZFS root file system using GPT partitioning and gptzfsboot. I then started using ZFS snapshots by using the sysutils/freebsd-snapshot port. This port basically just runs "zfs snapshot" and does some housekeeping.

The first snapshot went fine (when the machine was quiet). The second (when the machine was doing a portupgrade) caused a panic. All I have on the console is:

panic: dirtying snapshot

I traced this down to:

sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dataset.c:1104

void
dsl_dataset_dirty(dsl_dataset_t *ds, dmu_tx_t *tx)
{
        dsl_pool_t *dp;

        if (ds == NULL) /* this is the meta-objset */
                return;

        ASSERT(ds->ds_user_ptr != NULL);

        if (ds->ds_phys->ds_next_snap_obj != 0)
                panic("dirtying snapshot!");

        dp = ds->ds_dir->dd_pool;

        if (txg_list_add(&dp->dp_dirty_datasets, ds, tx->tx_txg) == 0) {
                /* up the hold count until we can be written out */
                dmu_buf_add_ref(ds->ds_dbuf, ds);
        }
}

I'm not sure what this means though.

Sadly I have no debugging enabled and no crash dump.

How-To-Repeat: Hard to say. Run ZFS root and do snapshots when the machine is busy? I've only seen it once.