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authorLars Ellenberg <lars.ellenberg@linbit.com>2013-01-21 15:43:41 +0100
committerPhilipp Reisner <philipp.reisner@linbit.com>2013-01-21 22:58:36 +0100
commit2681f7f6ce6c7416eb619d0fb19422bcc68bd9e1 (patch)
tree31b6a1a1830c4c81d917b545e659c1f46bcc1218 /drivers/block/drbd/drbd_req.c
parentd2ec180c23a5a1bfe34d8638b0342a47c00cf70f (diff)
downloadvexpress-lsk-2681f7f6ce6c7416eb619d0fb19422bcc68bd9e1.tar.gz
drbd: fix potential protocol error and resulting disconnect/reconnect
When we notice a disk failure on the receiving side, we stop sending it new incoming writes. Depending on exact timing of various events, the same transfer log epoch could end up containing both replicated (before we noticed the failure) and local-only requests (after we noticed the failure). The sanity checks in tl_release(), called when receiving a P_BARRIER_ACK, check that the ack'ed transfer log epoch matches the expected epoch, and the number of contained writes matches the number of ack'ed writes. In this case, they counted both replicated and local-only writes, but the peer only acknowledges those it has seen. We get a mismatch, resulting in a protocol error and disconnect/reconnect cycle. Messages logged are "BAD! BarrierAck #%u received with n_writes=%u, expected n_writes=%u!\n" A similar issue can also be triggered when starting a resync while having a healthy replication link, by invalidating one side, forcing a full sync, or attaching to a diskless node. Fix this by closing the current epoch if the state changes in a way that would cause the replication intent of the next write. Epochs now contain either only non-replicated, or only replicated writes. 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_req.c')
-rw-r--r--drivers/block/drbd/drbd_req.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index f58a4a4b4df..2b8303ad63c 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -168,7 +168,7 @@ static void wake_all_senders(struct drbd_tconn *tconn) {
}
/* must hold resource->req_lock */
-static void start_new_tl_epoch(struct drbd_tconn *tconn)
+void start_new_tl_epoch(struct drbd_tconn *tconn)
{
/* no point closing an epoch, if it is empty, anyways. */
if (tconn->current_tle_writes == 0)