Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 1535212c authored by Guoqing Jiang's avatar Guoqing Jiang Committed by Shaohua Li
Browse files

md-cluster: fix locking when node joins cluster during message broadcast 



If a node joins the cluster while a message broadcast
is under way, a lock issue could happen as follows.

For a cluster which included two nodes, if node A is
calling __sendmsg before up-convert CR to EX on ack,
and node B released CR on ack. But if a new node C
joins the cluster and it doesn't receive the message
which A sent before, so it could hold CR on ack before
A up-convert CR to EX on ack.

So a node joining the cluster should get an EX lock on
the "token" first to ensure no broadcast is ongoing,
then release it after held CR on ack.

Reviewed-by: default avatarNeilBrown <neilb@suse.com>
Signed-off-by: default avatarGuoqing Jiang <gqjiang@suse.com>
Signed-off-by: default avatarShaohua Li <shli@fb.com>
parent 5b0fb33e

drivers/md/md-cluster.c

+10 −3
Original line number Diff line number Diff line
@@ -781,17 +781,24 @@ static int join(struct mddev *mddev, int nodes) 
	cinfo->token_lockres = lockres_init(mddev, "token", NULL, 0);

	if (!cinfo->token_lockres)

		goto err;

	cinfo->ack_lockres = lockres_init(mddev, "ack", ack_bast, 0);

	if (!cinfo->ack_lockres)

		goto err;

	cinfo->no_new_dev_lockres = lockres_init(mddev, "no-new-dev", NULL, 0);

	if (!cinfo->no_new_dev_lockres)

		goto err;



	ret = dlm_lock_sync(cinfo->token_lockres, DLM_LOCK_EX);

	if (ret) {

		ret = -EAGAIN;

		pr_err("md-cluster: can't join cluster to avoid lock issue\n");

		goto err;

	}

	cinfo->ack_lockres = lockres_init(mddev, "ack", ack_bast, 0);

	if (!cinfo->ack_lockres)

		goto err;

	/* get sync CR lock on ACK. */

	if (dlm_lock_sync(cinfo->ack_lockres, DLM_LOCK_CR))

		pr_err("md-cluster: failed to get a sync CR lock on ACK!(%d)\n",

				ret);

	dlm_unlock_sync(cinfo->token_lockres);

	/* get sync CR lock on no-new-dev. */

	if (dlm_lock_sync(cinfo->no_new_dev_lockres, DLM_LOCK_CR))

		pr_err("md-cluster: failed to get a sync CR lock on no-new-dev!(%d)\n", ret);