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 <[email protected]> --- 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 -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
