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Commit 3b9ef85e authored by Lars Ellenberg's avatar Lars Ellenberg Committed by Philipp Reisner
Browse files

drbd: fix null pointer dereference with on-congestion policy when diskless 



We must not look at mdev->actlog, unless we have a get_ldev() reference.
It also does not make much sense to try to disconnect or pull-ahead of
the peer, if we don't have good local data.

Only even consider congestion policies, if our local disk is D_UP_TO_DATE.

Signed-off-by: default avatarPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: default avatarLars Ellenberg <lars.ellenberg@linbit.com>
parent 27012382

drivers/block/drbd/drbd_req.c

+11 −5
Original line number Original line Diff line number Diff line
@@ -823,7 +823,7 @@ static void complete_conflicting_writes(struct drbd_request *req) 
}

}





/* called within req_lock and rcu_read_lock() */

/* called within req_lock and rcu_read_lock() */

static bool conn_check_congested(struct drbd_conf *mdev)

static void maybe_pull_ahead(struct drbd_conf *mdev)

{

{

	struct drbd_tconn *tconn = mdev->tconn;

	struct drbd_tconn *tconn = mdev->tconn;

	struct net_conf *nc;

	struct net_conf *nc;
@@ -834,7 +834,14 @@ static bool conn_check_congested(struct drbd_conf *mdev) 
	on_congestion = nc ? nc->on_congestion : OC_BLOCK;

	on_congestion = nc ? nc->on_congestion : OC_BLOCK;

	if (on_congestion == OC_BLOCK ||

	if (on_congestion == OC_BLOCK ||

	    tconn->agreed_pro_version < 96)

	    tconn->agreed_pro_version < 96)

		return false;

		return;



	/* If I don't even have good local storage, we can not reasonably try

	 * to pull ahead of the peer. We also need the local reference to make

	 * sure mdev->act_log is there.

	 */

	if (!get_ldev_if_state(mdev, D_UP_TO_DATE))

		return;





	if (nc->cong_fill &&

	if (nc->cong_fill &&

	    atomic_read(&mdev->ap_in_flight) >= nc->cong_fill) {

	    atomic_read(&mdev->ap_in_flight) >= nc->cong_fill) {
@@ -857,8 +864,7 @@ static bool conn_check_congested(struct drbd_conf *mdev) 
		else  /*nc->on_congestion == OC_DISCONNECT */

		else  /*nc->on_congestion == OC_DISCONNECT */

			_drbd_set_state(_NS(mdev, conn, C_DISCONNECTING), 0, NULL);

			_drbd_set_state(_NS(mdev, conn, C_DISCONNECTING), 0, NULL);

	}

	}



	put_ldev(mdev);

	return congested;

}

}





/* If this returns false, and req->private_bio is still set,

/* If this returns false, and req->private_bio is still set,
@@ -923,7 +929,7 @@ static int drbd_process_write_request(struct drbd_request *req) 
	rcu_read_lock();

	rcu_read_lock();

	remote = drbd_should_do_remote(mdev->state);

	remote = drbd_should_do_remote(mdev->state);

	if (remote) {

	if (remote) {

		conn_check_congested(mdev);

		maybe_pull_ahead(mdev);

		remote = drbd_should_do_remote(mdev->state);

		remote = drbd_should_do_remote(mdev->state);

	}

	}

	send_oos = drbd_should_send_out_of_sync(mdev->state);

	send_oos = drbd_should_send_out_of_sync(mdev->state);