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Commit 802c6d96 authored by Alex Elder's avatar Alex Elder
Browse files

rbd: define common queue_con_delay() 



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: default avatarAlex Elder <elder@inktank.com>
Reviewed-by: default avatarSage Weil <sage@inktank.com>
parent 8618e30b

net/ceph/messenger.c

+23 −15
Original line number Diff line number Diff line
@@ -2244,22 +2244,33 @@ static int try_read(struct ceph_connection *con) 




/*

 * 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 @@ static void con_work(struct work_struct *work) 


	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;