drbd: Receiving of delay_probes

Delay_probes are new packets in the DRBD protocol, which allow
DRBD to know the current delay packets have on the data socket.
(relative to the meta data socket)

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

1 files changed, 19 insertions, 1 deletions

diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index 2409de12f013..fd7615f1e526 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -209,8 +209,11 @@ enum drbd_packets {
         P_RS_IS_IN_SYNC       = 0x22, /* meta socket */
         P_SYNC_PARAM89        = 0x23, /* data socket, protocol version 89 replacement for P_SYNC_PARAM */
         P_COMPRESSED_BITMAP   = 0x24, /* compressed or otherwise encoded bitmap transfer */
+        /* P_CKPT_FENCE_REQ      = 0x25, * currently reserved for protocol D */
+        /* P_CKPT_DISABLE_REQ    = 0x26, * currently reserved for protocol D */
+        P_DELAY_PROBE         = 0x27, /* is used on BOTH sockets */
 
-        P_MAX_CMD             = 0x25,
+        P_MAX_CMD             = 0x28,
         P_MAY_IGNORE          = 0x100, /* Flag to test if (cmd > P_MAY_IGNORE) ... */
         P_MAX_OPT_CMD         = 0x101,
 
@@ -540,6 +543,18 @@ struct p_compressed_bm {
         u8 code[0];
 } __packed;
 
+struct p_delay_probe {
+        struct p_header head;
+        u32     seq_num; /* sequence number to match the two probe packets */
+        u32     offset;  /* usecs the probe got sent after the reference time point */
+} __packed;
+
+struct delay_probe {
+        struct list_head list;
+        int seq_num;
+        struct timeval time;
+};
+
 /* DCBP: Drbd Compressed Bitmap Packet ... */
 static inline enum drbd_bitmap_code
 DCBP_get_code(struct p_compressed_bm *p)
@@ -1028,6 +1043,9 @@ struct drbd_conf {
         u64 ed_uuid; /* UUID of the exposed data */
         struct mutex state_mutex;
         char congestion_reason;  /* Why we where congested... */
+        struct list_head delay_probes; /* protected by peer_seq_lock */
+        int data_delay;   /* Delay of packets on the data-sock behind meta-sock */
+        atomic_t delay_seq; /* To generate sequence numbers of delay probes */
 };
 
 static inline struct drbd_conf *minor_to_mdev(unsigned int minor)