This is an old protocol extension that allows the client and server to
avoid resending old messages after a reconnect (following a socket error).
Instead, the exchange their sequence numbers during the handshake. This
avoids sending a bunch of useless data over the socket.
It has been supported in the server code since v0.22 (Sep 2010).
Signed-off-by: Sage Weil <sage@xxxxxxxxxxx>
---
include/linux/ceph/ceph_features.h | 2 ++
include/linux/ceph/msgr.h | 1 +
net/ceph/messenger.c | 47 +++++++++++++++++++++++++++++++++---
3 files changed, 46 insertions(+), 4 deletions(-)
diff --git a/include/linux/ceph/ceph_features.h b/include/linux/ceph/ceph_features.h
index 76554ce..4c420803 100644
--- a/include/linux/ceph/ceph_features.h
+++ b/include/linux/ceph/ceph_features.h
@@ -41,6 +41,7 @@
*/
#define CEPH_FEATURES_SUPPORTED_DEFAULT \
(CEPH_FEATURE_NOSRCADDR | \
+ CEPH_FEATURE_RECONNECT_SEQ | \
CEPH_FEATURE_PGID64 | \
CEPH_FEATURE_PGPOOL3 | \
CEPH_FEATURE_OSDENC | \
@@ -51,6 +52,7 @@
#define CEPH_FEATURES_REQUIRED_DEFAULT \
(CEPH_FEATURE_NOSRCADDR | \
+ CEPH_FEATURE_RECONNECT_SEQ | \
CEPH_FEATURE_PGID64 | \
CEPH_FEATURE_PGPOOL3 | \
CEPH_FEATURE_OSDENC)
diff --git a/include/linux/ceph/msgr.h b/include/linux/ceph/msgr.h
index 680d3d6..3d94a73 100644
--- a/include/linux/ceph/msgr.h
+++ b/include/linux/ceph/msgr.h
@@ -87,6 +87,7 @@ struct ceph_entity_inst {
#define CEPH_MSGR_TAG_BADPROTOVER 10 /* bad protocol version */
#define CEPH_MSGR_TAG_BADAUTHORIZER 11 /* bad authorizer */
#define CEPH_MSGR_TAG_FEATURES 12 /* insufficient features */
+#define CEPH_MSGR_TAG_SEQ 13 /* 64-bit int follows with seen seq number */
/*
diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index 997dacc..2bf2806 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -1247,6 +1247,24 @@ static void prepare_write_ack(struct ceph_connection *con)
}
/*
+ * Prepare to share the seq during handshake
+ */
+static void prepare_write_seq(struct ceph_connection *con)
+{
+ dout("prepare_write_seq %p %llu -> %llu\n", con,
+ con->in_seq_acked, con->in_seq);
+ con->in_seq_acked = con->in_seq;
+
+ con_out_kvec_reset(con);
+
+ con->out_temp_ack = cpu_to_le64(con->in_seq_acked);
+ con_out_kvec_add(con, sizeof (con->out_temp_ack),
+ &con->out_temp_ack);
+
+ con_flag_set(con, CON_FLAG_WRITE_PENDING);
+}
+
+/*
* Prepare to write keepalive byte.
*/
static void prepare_write_keepalive(struct ceph_connection *con)
@@ -1582,6 +1600,13 @@ static void prepare_read_ack(struct ceph_connection *con)
con->in_base_pos = 0;
}
+static void prepare_read_seq(struct ceph_connection *con)
+{
+ dout("prepare_read_seq %p\n", con);
+ con->in_base_pos = 0;
+ con->in_tag = CEPH_MSGR_TAG_SEQ;
+}
+
static void prepare_read_tag(struct ceph_connection *con)
{
dout("prepare_read_tag %p\n", con);
@@ -2059,6 +2084,7 @@ static int process_connect(struct ceph_connection *con)
prepare_read_connect(con);
break;
+ case CEPH_MSGR_TAG_SEQ:
case CEPH_MSGR_TAG_READY:
if (req_feat & ~server_feat) {
pr_err("%s%lld %s protocol feature mismatch,"
@@ -2089,7 +2115,12 @@ static int process_connect(struct ceph_connection *con)
con->delay = 0; /* reset backoff memory */
- prepare_read_tag(con);
+ if (con->in_reply.tag == CEPH_MSGR_TAG_SEQ) {
+ prepare_write_seq(con);
+ prepare_read_seq(con);
+ } else {
+ prepare_read_tag(con);
+ }
break;
case CEPH_MSGR_TAG_WAIT:
@@ -2123,7 +2154,6 @@ static int read_partial_ack(struct ceph_connection *con)
return read_partial(con, end, size, &con->in_temp_ack);
}
-
/*
* We can finally discard anything that's been acked.
*/
@@ -2148,8 +2178,6 @@ static void process_ack(struct ceph_connection *con)
}
-
-
static int read_partial_message_section(struct ceph_connection *con,
struct kvec *section,
unsigned int sec_len, u32 *crc)
@@ -2628,6 +2656,17 @@ more:
if (con->in_base_pos)
goto more;
}
+ if (con->in_tag == CEPH_MSGR_TAG_SEQ) {
+ /*
+ * the final seq exchange is semantically equivalent
+ * to an ACK; re-use those helpers.
+ */
+ ret = read_partial_ack(con);
+ if (ret <= 0)
+ goto out;
+ process_ack(con);
+ goto more;
+ }
if (con->in_tag == CEPH_MSGR_TAG_READY) {
/*
* what's next?
--
1.7.9.5
--
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