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Commit 3a23083b authored by Sage Weil's avatar Sage Weil
Browse files

libceph: implement RECONNECT_SEQ feature 



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: default avatarSage Weil <sage@inktank.com>
Reviewed-by: default avatarAlex Elder <elder@inktank.com>
parent 022f3e2e

include/linux/ceph/ceph_features.h

+2 −0
Original line number Diff line number Diff line
@@ -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)

include/linux/ceph/msgr.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */





/*

net/ceph/messenger.c

+38 −5
Original line number Diff line number Diff line
@@ -1246,6 +1246,24 @@ static void prepare_write_ack(struct ceph_connection *con) 
	con_flag_set(con, CON_FLAG_WRITE_PENDING);

}



/*

 * 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.

 */
@@ -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 */



		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)
@@ -2672,7 +2700,12 @@ static int try_read(struct ceph_connection *con) 
			prepare_read_tag(con);

		goto more;

	}

	if (con->in_tag == CEPH_MSGR_TAG_ACK) {

	if (con->in_tag == CEPH_MSGR_TAG_ACK ||

	    con->in_tag == CEPH_MSGR_TAG_SEQ) {

		/*

		 * the final handshake seq exchange is semantically

		 * equivalent to an ACK

		 */

		ret = read_partial_ack(con);

		if (ret <= 0)

			goto out;