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authorPhilipp Reisner <philipp.reisner@linbit.com>2012-11-22 17:06:00 +0100
committerPhilipp Reisner <philipp.reisner@linbit.com>2012-12-06 13:00:33 +0100
commit13c76aba7846647f86d479293ae0a0adc1ca840a (patch)
treea729c2b6f77403829c712f118d3cc1ff65d901b7 /drivers/block/drbd/drbd_receiver.c
parent691631c0652bc47e6d20b0d981e23a9025fd794e (diff)
downloadvexpress-lsk-13c76aba7846647f86d479293ae0a0adc1ca840a.tar.gz
drbd: close race between drbd_set_role and drbd_connect
drbd_set_role(, R_PRIMARY, ) does the state change to Primary, some more housekeeping, and possibly generates a new UUID set. All of this holding the "state_mutex". The connection handshake involves sending of various state information, including the current data generation UUID set, and two connection state changes from C_WF_CONNECTION to C_WF_REPORT_PARAMS further to a number of different outcomes, resync being one of them. If the connection handshake happens between the state change to Primary and the generation of the new UUIDs, the resync decision based on the old UUID set may be confused, depending on circumstances. Make sure that, before we do the handshake, any promotion to Primary role will either be complete (including the housekeeping stuff), or can see, and serialize with, the ongoing handshake, based on the "STATE_SENT" bit, which is set when we start the handshake, and cleared only when we leave C_WF_REPORT_PARAMS again. Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com> Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Diffstat (limited to 'drivers/block/drbd/drbd_receiver.c')
-rw-r--r--drivers/block/drbd/drbd_receiver.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 1599a1a6f1f..a9eccfc6079 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -1037,6 +1037,16 @@ randomize:
rcu_read_lock();
idr_for_each_entry(&tconn->volumes, mdev, vnr) {
kref_get(&mdev->kref);
+ /* Prevent a race between resync-handshake and
+ * being promoted to Primary.
+ *
+ * Grab and release the state mutex, so we know that any current
+ * drbd_set_role() is finished, and any incoming drbd_set_role
+ * will see the STATE_SENT flag, and wait for it to be cleared.
+ */
+ mutex_lock(mdev->state_mutex);
+ mutex_unlock(mdev->state_mutex);
+
rcu_read_unlock();
if (discard_my_data)