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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: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>
This commit is contained in:
Sage Weil 2013-03-25 08:47:40 -07:00
parent 022f3e2ee2
commit 3a23083bda
3 changed files with 41 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/linux/ceph/ceph_features.h
View File

@ -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)

1
include/linux/ceph/msgr.h
View File

@ -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 */
/*

43
net/ceph/messenger.c
View File

@ -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 */
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)
@ -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;