Commit f479ea06 authored by Lars Ellenberg's avatar Lars Ellenberg Committed by Philipp Reisner
Browse files

drbd: send intermediate state change results to the peer 



DRBD state changes schedule after_state_ch() actions to a worker thread,
which decides on the old and new states of that change, whether to send
an informational state update packet (P_STATE) to the peer.
If it decides to drbd_send_state(), it would however always send the
_curent_ state, which, if a second state change happens before the
after_state_ch() of the first ran, may "fast-forward" the peer's view
about this node.  In most cases that is harmless, but sometimes this can
confuse DRBD, for example into not actually starting a necessary resync
if you do a very tight detach/attach loop on a Connected Secondary.

Fix this by always sending the "new" state of the respective state
transition which scheduled this after_state_ch() work.

Signed-off-by: default avatarPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: default avatarLars Ellenberg <lars.ellenberg@linbit.com>
parent a2e91381

drivers/block/drbd/drbd_int.h

+2 −2
Original line number Diff line number Diff line
@@ -1229,8 +1229,8 @@ extern int drbd_send_uuids(struct drbd_conf *mdev); 
extern int drbd_send_uuids_skip_initial_sync(struct drbd_conf *mdev);

extern int drbd_gen_and_send_sync_uuid(struct drbd_conf *mdev);

extern int drbd_send_sizes(struct drbd_conf *mdev, int trigger_reply, enum dds_flags flags);

extern int _drbd_send_state(struct drbd_conf *mdev);

extern int drbd_send_state(struct drbd_conf *mdev);

extern int drbd_send_state(struct drbd_conf *mdev, union drbd_state s);

extern int drbd_send_current_state(struct drbd_conf *mdev);

extern int _drbd_send_cmd(struct drbd_conf *mdev, struct socket *sock,

			enum drbd_packets cmd, struct p_header80 *h,

			size_t size, unsigned msg_flags);

drivers/block/drbd/drbd_main.c

+42 −11
Original line number Diff line number Diff line
@@ -1487,7 +1487,7 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os, 
	/* Do not change the order of the if above and the two below... */

	if (os.pdsk == D_DISKLESS && ns.pdsk > D_DISKLESS) {      /* attach on the peer */

		drbd_send_uuids(mdev);

		drbd_send_state(mdev);

		drbd_send_state(mdev, ns);

	}

	/* No point in queuing send_bitmap if we don't have a connection

	 * anymore, so check also the _current_ state, not only the new state
@@ -1552,14 +1552,14 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os, 
	    os.disk == D_ATTACHING && ns.disk == D_NEGOTIATING) {

		drbd_send_sizes(mdev, 0, 0);  /* to start sync... */

		drbd_send_uuids(mdev);

		drbd_send_state(mdev);

		drbd_send_state(mdev, ns);

	}



	/* We want to pause/continue resync, tell peer. */

	if (ns.conn >= C_CONNECTED &&

	     ((os.aftr_isp != ns.aftr_isp) ||

	      (os.user_isp != ns.user_isp)))

		drbd_send_state(mdev);

		drbd_send_state(mdev, ns);



	/* In case one of the isp bits got set, suspend other devices. */

	if ((!os.aftr_isp && !os.peer_isp && !os.user_isp) &&
@@ -1569,10 +1569,10 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os, 
	/* Make sure the peer gets informed about eventual state

	   changes (ISP bits) while we were in WFReportParams. */

	if (os.conn == C_WF_REPORT_PARAMS && ns.conn >= C_CONNECTED)

		drbd_send_state(mdev);

		drbd_send_state(mdev, ns);



	if (os.conn != C_AHEAD && ns.conn == C_AHEAD)

		drbd_send_state(mdev);

		drbd_send_state(mdev, ns);



	/* We are in the progress to start a full sync... */

	if ((os.conn != C_STARTING_SYNC_T && ns.conn == C_STARTING_SYNC_T) ||
@@ -1612,7 +1612,7 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os, 
				"ASSERT FAILED: disk is %s during detach\n",

				drbd_disk_str(mdev->state.disk));



		if (drbd_send_state(mdev))

		if (drbd_send_state(mdev, ns))

			dev_info(DEV, "Notified peer that I am detaching my disk\n");



		drbd_rs_cancel_all(mdev);
@@ -1642,7 +1642,7 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os, 
                mdev->rs_failed = 0;

                atomic_set(&mdev->rs_pending_cnt, 0);



		if (drbd_send_state(mdev))

		if (drbd_send_state(mdev, ns))

			dev_info(DEV, "Notified peer that I'm now diskless.\n");

		/* corresponding get_ldev in __drbd_set_state

		 * this may finally trigger drbd_ldev_destroy. */
@@ -1651,7 +1651,7 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os, 


	/* Notify peer that I had a local IO error, and did not detached.. */

	if (os.disk == D_UP_TO_DATE && ns.disk == D_INCONSISTENT)

		drbd_send_state(mdev);

		drbd_send_state(mdev, ns);



	/* Disks got bigger while they were detached */

	if (ns.disk > D_NEGOTIATING && ns.pdsk > D_NEGOTIATING &&
@@ -1669,7 +1669,7 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os, 
	/* sync target done with resync.  Explicitly notify peer, even though

	 * it should (at least for non-empty resyncs) already know itself. */

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

		drbd_send_state(mdev);

		drbd_send_state(mdev, ns);



	/* This triggers bitmap writeout of potentially still unwritten pages

	 * if the resync finished cleanly, or aborted because of peer disk
@@ -2191,10 +2191,10 @@ int drbd_send_sizes(struct drbd_conf *mdev, int trigger_reply, enum dds_flags fl 
}



/**

 * drbd_send_state() - Sends the drbd state to the peer

 * drbd_send_current_state() - Sends the drbd state to the peer

 * @mdev:	DRBD device.

 */

int drbd_send_state(struct drbd_conf *mdev)

int drbd_send_current_state(struct drbd_conf *mdev)

{

	struct socket *sock;

	struct p_state p;
@@ -2220,6 +2220,37 @@ int drbd_send_state(struct drbd_conf *mdev) 
	return ok;

}



/**

 * drbd_send_state() - After a state change, sends the new state to the peer

 * @mdev:	DRBD device.

 * @state:	the state to send, not necessarily the current state.

 *

 * Each state change queues an "after_state_ch" work, which will eventually

 * send the resulting new state to the peer. If more state changes happen

 * between queuing and processing of the after_state_ch work, we still

 * want to send each intermediary state in the order it occurred.

 */

int drbd_send_state(struct drbd_conf *mdev, union drbd_state state)

{

	struct socket *sock;

	struct p_state p;

	int ok = 0;



	mutex_lock(&mdev->data.mutex);



	p.state = cpu_to_be32(state.i);

	sock = mdev->data.socket;



	if (likely(sock != NULL)) {

		ok = _drbd_send_cmd(mdev, sock, P_STATE,

				    (struct p_header80 *)&p, sizeof(p), 0);

	}



	mutex_unlock(&mdev->data.mutex);



	return ok;

}



int drbd_send_state_req(struct drbd_conf *mdev,

	union drbd_state mask, union drbd_state val)

{

drivers/block/drbd/drbd_nl.c

+1 −1
Original line number Diff line number Diff line
@@ -432,7 +432,7 @@ drbd_set_role(struct drbd_conf *mdev, enum drbd_role new_role, int force) 
		/* if this was forced, we should consider sync */

		if (forced)

			drbd_send_uuids(mdev);

		drbd_send_state(mdev);

		drbd_send_current_state(mdev);

	}



	drbd_md_sync(mdev);

drivers/block/drbd/drbd_receiver.c

+2 −2
Original line number Diff line number Diff line
@@ -899,7 +899,7 @@ retry: 
	drbd_send_sync_param(mdev, &mdev->sync_conf);

	drbd_send_sizes(mdev, 0, 0);

	drbd_send_uuids(mdev);

	drbd_send_state(mdev);

	drbd_send_current_state(mdev);

	clear_bit(USE_DEGR_WFC_T, &mdev->flags);

	clear_bit(RESIZE_PENDING, &mdev->flags);
@@ -3294,7 +3294,7 @@ static int receive_state(struct drbd_conf *mdev, enum drbd_packets cmd, unsigned 
			/* Nowadays only used when forcing a node into primary role and

			   setting its disk to UpToDate with that */

			drbd_send_uuids(mdev);

			drbd_send_state(mdev);

			drbd_send_current_state(mdev);

		}

	}

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