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libceph: fix msgr standby handling 

The standby logic used to be pretty dependent on the work requeueing
behavior that changed when we switched to WQ_NON_REENTRANT.  It was also
very fragile.

Restructure things so that:
 - We clear WRITE_PENDING when we set STANDBY.  This ensures we will
   requeue work when we wake up later.
 - con_work backs off if STANDBY is set.  There is nothing to do if we are
   in standby.
 - clear_standby() helper is called by both con_send() and con_keepalive(),
   the two actions that can wake us up again.  Move the connect_seq++
   logic here.

Signed-off-by: Sage Weil <sage@newdream.net>
This commit is contained in:
Sage Weil 2011-03-04 12:25:05 -08:00
parent e76661d0a5
commit e00de341fd
1 changed files with 22 additions and 8 deletions
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30
net/ceph/messenger.c
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@ -1712,14 +1712,6 @@ more:
/* open the socket first? */
if (con->sock == NULL) {
/*
* if we were STANDBY and are reconnecting _this_
* connection, bump connect_seq now. Always bump
* global_seq.
*/
if (test_and_clear_bit(STANDBY, &con->state))
con->connect_seq++;
prepare_write_banner(msgr, con);
prepare_write_connect(msgr, con, 1);
prepare_read_banner(con);
@ -1962,6 +1954,10 @@ static void con_work(struct work_struct *work)
}
}
if (test_bit(STANDBY, &con->state)) {
dout("con_work %p STANDBY\n", con);
goto done;
}
if (test_bit(CLOSED, &con->state)) { /* e.g. if we are replaced */
dout("con_work CLOSED\n");
con_close_socket(con);
@ -2022,6 +2018,8 @@ static void ceph_fault(struct ceph_connection *con)
* the connection in a STANDBY state */
if (list_empty(&con->out_queue) &&
!test_bit(KEEPALIVE_PENDING, &con->state)) {
dout("fault %p setting STANDBY clearing WRITE_PENDING\n", con);
clear_bit(WRITE_PENDING, &con->state);
set_bit(STANDBY, &con->state);
} else {
/* retry after a delay. */
@ -2117,6 +2115,19 @@ void ceph_messenger_destroy(struct ceph_messenger *msgr)
}
EXPORT_SYMBOL(ceph_messenger_destroy);
static void clear_standby(struct ceph_connection *con)
{
/* come back from STANDBY? */
if (test_and_clear_bit(STANDBY, &con->state)) {
mutex_lock(&con->mutex);
dout("clear_standby %p and ++connect_seq\n", con);
con->connect_seq++;
WARN_ON(test_bit(WRITE_PENDING, &con->state));
WARN_ON(test_bit(KEEPALIVE_PENDING, &con->state));
mutex_unlock(&con->mutex);
}
}
/*
* Queue up an outgoing message on the given connection.
*/
@ -2149,6 +2160,7 @@ void ceph_con_send(struct ceph_connection *con, struct ceph_msg *msg)
/* if there wasn't anything waiting to send before, queue
* new work */
clear_standby(con);
if (test_and_set_bit(WRITE_PENDING, &con->state) == 0)
queue_con(con);
}
@ -2214,6 +2226,8 @@ void ceph_con_revoke_message(struct ceph_connection *con, struct ceph_msg *msg)
*/
void ceph_con_keepalive(struct ceph_connection *con)
{
dout("con_keepalive %p\n", con);
clear_standby(con);
if (test_and_set_bit(KEEPALIVE_PENDING, &con->state) == 0 &&
test_and_set_bit(WRITE_PENDING, &con->state) == 0)
queue_con(con);