From: Lars Ellenberg <lars.ellenb...@linbit.com>
In a multiple error scenario, we may end up with a "frozen" Primary,
that has no access to any data (no local disk, no replication link).
If we then resume-io, we try to generate a new data generation id,
which will fail if there is no longer a local disk.
Double check for available local data,
which prevents the NULL pointer deref.
If we are diskless, turn the resume-io in this situation
into the first stage of a "force down", by bumping the "effective" data
gen id, which will prevent later attach or connect to the former data
set without first being demoted (deconfigured).
Signed-off-by: Philipp Reisner <philipp.reis...@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenb...@linbit.com>
---
drivers/block/drbd/drbd_nl.c | 25 ++++++++++++++++++++++++-
1 file changed, 24 insertions(+), 1 deletion(-)
diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index f35cefb..5e4adff 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -2920,7 +2920,30 @@ int drbd_adm_resume_io(struct sk_buff *skb, struct
genl_info *info)
mutex_lock(&adm_ctx.resource->adm_mutex);
device = adm_ctx.device;
if (test_bit(NEW_CUR_UUID, &device->flags)) {
- drbd_uuid_new_current(device);
+ if (get_ldev_if_state(device, D_ATTACHING)) {
+ drbd_uuid_new_current(device);
+ put_ldev(device);
+ } else {
+ /* This is effectively a multi-stage "forced down".
+ * The NEW_CUR_UUID bit is supposedly only set, if we
+ * lost the replication connection, and are configured
+ * to freeze IO and wait for some fence-peer handler.
+ * So we still don't have a replication connection.
+ * And now we don't have a local disk either. After
+ * resume, we will fail all pending and new IO, because
+ * we don't have any data anymore. Which means we will
+ * eventually be able to terminate all users of this
+ * device, and then take it down. By bumping the
+ * "effective" data uuid, we make sure that you really
+ * need to tear down before you reconfigure, we will
+ * the refuse to re-connect or re-attach (because no
+ * matching real data uuid exists).
+ */
+ u64 val;
+ get_random_bytes(&val, sizeof(u64));
+ drbd_set_ed_uuid(device, val);
+ drbd_warn(device, "Resumed without access to data;
please tear down before attempting to re-configure.\n");
+ }
clear_bit(NEW_CUR_UUID, &device->flags);
}
drbd_suspend_io(device);
--
1.9.1
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