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rbd: define common queue_con_delay()

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This patch defines a single function, queue_con_delay() to call
queue_delayed_work() for a connection.  It basically generalizes
what was previously queue_con() by adding the delay argument.
queue_con() is now a simple helper that passes 0 for its delay.
queue_con_delay() returns 0 if it queued work or an errno if it
did not for some reason.

If con_work() finds the BACKOFF flag set for a connection, it now
calls queue_con_delay() to handle arranging to start again after a
delay.

Note about connection reference counts:  con_work() only ever gets
called as a work item function.  At the time that work is scheduled,
a reference to the connection is acquired, and the corresponding
con_work() call is then responsible for dropping that reference
before it returns.

Previously, the backoff handling inside con_work() silently handed
off its reference to delayed work it scheduled.  Now that
queue_con_delay() is used, a new reference is acquired for the
newly-scheduled work, and the original reference is dropped by the
con->ops->put() call at the end of the function.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
This commit is contained in:
Alex Elder 2012-10-08 20:37:30 -07:00
parent 8618e30bc1
commit 802c6d967f
1 changed files with 23 additions and 15 deletions
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38
net/ceph/messenger.c
View File

@ -2244,22 +2244,33 @@ bad_tag:
/*
* Atomically queue work on a connection. Bump @con reference to
* avoid races with connection teardown.
* Atomically queue work on a connection after the specified delay.
* Bump @con reference to avoid races with connection teardown.
* Returns 0 if work was queued, or an error code otherwise.
*/
static void queue_con(struct ceph_connection *con)
static int queue_con_delay(struct ceph_connection *con, unsigned long delay)
{
if (!con->ops->get(con)) {
dout("queue_con %p ref count 0\n", con);
return;
dout("%s %p ref count 0\n", __func__, con);
return -ENOENT;
}
if (!queue_delayed_work(ceph_msgr_wq, &con->work, 0)) {
dout("queue_con %p - already queued\n", con);
if (!queue_delayed_work(ceph_msgr_wq, &con->work, delay)) {
dout("%s %p - already queued\n", __func__, con);
con->ops->put(con);
} else {
dout("queue_con %p\n", con);
return -EBUSY;
}
dout("%s %p %lu\n", __func__, con, delay);
return 0;
}
static void queue_con(struct ceph_connection *con)
{
(void) queue_con_delay(con, 0);
}
/*
@ -2294,14 +2305,11 @@ restart:
if (test_and_clear_bit(CON_FLAG_BACKOFF, &con->flags)) {
dout("con_work %p backing off\n", con);
if (queue_delayed_work(ceph_msgr_wq, &con->work,
round_jiffies_relative(con->delay))) {
dout("con_work %p backoff %lu\n", con, con->delay);
mutex_unlock(&con->mutex);
return;
} else {
ret = queue_con_delay(con, round_jiffies_relative(con->delay));
if (ret) {
dout("con_work %p FAILED to back off %lu\n", con,
con->delay);
BUG_ON(ret == -ENOENT);
set_bit(CON_FLAG_BACKOFF, &con->flags);
}
goto done;