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Commit 63106d3c authored by Philipp Reisner's avatar Philipp Reisner
Browse files

drbd: Removed a race that could cause unexpected execution of w_make_resync_request() 



The actual race happened int the drbd_start_resync() function. Where
drbd_resync_finished() -> __drbd_set_state() set STOP_SYNC_TIMER and
armed the timer.

If the timer fired before execution reaches the mod_timer statement
at the end of drbd_start_resync() the latter would cause an
unexpected call to w_make_resync_request().

Removed the STOP_SYNC_TIMER bit, and base it on the connection state.

The STOP_SYNC_TIMER bit probably originates probably the time before
the state engine.

Signed-off-by: default avatarPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: default avatarLars Ellenberg <lars.ellenberg@linbit.com>
parent ef50a3e3

drivers/block/drbd/drbd_int.h

+0 −1
Original line number Diff line number Diff line
@@ -827,7 +827,6 @@ enum { 
	SIGNAL_ASENDER,		/* whether asender wants to be interrupted */

	SEND_PING,		/* whether asender should send a ping asap */



	STOP_SYNC_TIMER,	/* tell timer to cancel itself */

	UNPLUG_QUEUED,		/* only relevant with kernel 2.4 */

	UNPLUG_REMOTE,		/* sending a "UnplugRemote" could help */

	MD_DIRTY,		/* current uuids and flags not yet on disk */

drivers/block/drbd/drbd_main.c

+2 −16
Original line number Diff line number Diff line
@@ -1052,12 +1052,6 @@ int __drbd_set_state(struct drbd_conf *mdev, 
	wake_up(&mdev->misc_wait);

	wake_up(&mdev->state_wait);



	/*   post-state-change actions   */

	if (os.conn >= C_SYNC_SOURCE   && ns.conn <= C_CONNECTED) {

		set_bit(STOP_SYNC_TIMER, &mdev->flags);

		mod_timer(&mdev->resync_timer, jiffies);

	}



	/* aborted verify run. log the last position */

	if ((os.conn == C_VERIFY_S || os.conn == C_VERIFY_T) &&

	    ns.conn < C_CONNECTED) {
@@ -1072,22 +1066,14 @@ int __drbd_set_state(struct drbd_conf *mdev, 
		dev_info(DEV, "Syncer continues.\n");

		mdev->rs_paused += (long)jiffies

				  -(long)mdev->rs_mark_time[mdev->rs_last_mark];

		if (ns.conn == C_SYNC_TARGET) {

			if (!test_and_clear_bit(STOP_SYNC_TIMER, &mdev->flags))

		if (ns.conn == C_SYNC_TARGET)

			mod_timer(&mdev->resync_timer, jiffies);

			/* This if (!test_bit) is only needed for the case

			   that a device that has ceased to used its timer,

			   i.e. it is already in drbd_resync_finished() gets

			   paused and resumed. */

		}

	}



	if ((os.conn == C_SYNC_TARGET  || os.conn == C_SYNC_SOURCE) &&

	    (ns.conn == C_PAUSED_SYNC_T || ns.conn == C_PAUSED_SYNC_S)) {

		dev_info(DEV, "Resync suspended\n");

		mdev->rs_mark_time[mdev->rs_last_mark] = jiffies;

		if (ns.conn == C_PAUSED_SYNC_T)

			set_bit(STOP_SYNC_TIMER, &mdev->flags);

	}



	if (os.conn == C_CONNECTED &&

drivers/block/drbd/drbd_receiver.c

+0 −1
Original line number Diff line number Diff line
@@ -3803,7 +3803,6 @@ static void drbd_disconnect(struct drbd_conf *mdev) 


	/* make sure syncer is stopped and w_resume_next_sg queued */

	del_timer_sync(&mdev->resync_timer);

	set_bit(STOP_SYNC_TIMER, &mdev->flags);

	resync_timer_fn((unsigned long)mdev);



	/* wait for all w_e_end_data_req, w_e_end_rsdata_req, w_send_barrier,

drivers/block/drbd/drbd_worker.c

+9 −12
Original line number Diff line number Diff line
@@ -395,25 +395,22 @@ defer: 


void resync_timer_fn(unsigned long data)

{

	unsigned long flags;

	struct drbd_conf *mdev = (struct drbd_conf *) data;

	int queue;



	spin_lock_irqsave(&mdev->req_lock, flags);



	if (likely(!test_and_clear_bit(STOP_SYNC_TIMER, &mdev->flags))) {

	queue = 1;

		if (mdev->state.conn == C_VERIFY_S)

	switch (mdev->state.conn) {

	case C_VERIFY_S:

		mdev->resync_work.cb = w_make_ov_request;

		else

		break;

	case C_SYNC_TARGET:

		mdev->resync_work.cb = w_make_resync_request;

	} else {

		break;

	default:

		queue = 0;

		mdev->resync_work.cb = w_resync_inactive;

	}



	spin_unlock_irqrestore(&mdev->req_lock, flags);



	/* harmless race: list_empty outside data.work.q_lock */

	if (list_empty(&mdev->resync_work.list) && queue)

		drbd_queue_work(&mdev->data.work, &mdev->resync_work);