ocfs2/dlm: fix a dead lock (6d98c3cc) · Commits · 戴 / test

When we have to take both dlm->master_lock and lockres->spinlock, take them in order lockres->spinlock and then dlm->master_lock. The patch fixes a violation of the rule. We can simply move taking dlm->master_lock to where we have dropped res->spinlock since when we access res->state and free mle memory we don't need master_lock's protection. Signed-off-by:

Wengang Wang <wen.gang.wang@oracle.com> Cc: stable@kernel.org Signed-off-by:

Joel Becker <joel.becker@oracle.com>

fs/ocfs2/dlm/dlmmaster.c

+2 −3

Original line number	Diff line number	Diff line
		@@ -3050,8 +3050,6 @@ int dlm_migrate_request_handler(struct o2net_msg msg, u32 len, void data,
		/* check for pre-existing lock */
		spin_lock(&dlm->spinlock);
		res = __dlm_lookup_lockres(dlm, name, namelen, hash);
		spin_lock(&dlm->master_lock);

		if (res) {
		spin_lock(&res->spinlock);
		if (res->state & DLM_LOCK_RES_RECOVERING) {
		@@ -3069,14 +3067,15 @@ int dlm_migrate_request_handler(struct o2net_msg msg, u32 len, void data,
		spin_unlock(&res->spinlock);
		}

		spin_lock(&dlm->master_lock);
		/* ignore status. only nonzero status would BUG. */
		ret = dlm_add_migration_mle(dlm, res, mle, &oldmle,
		name, namelen,
		migrate->new_master,
		migrate->master);

		unlock:
		spin_unlock(&dlm->master_lock);
		unlock:
		spin_unlock(&dlm->spinlock);

		if (oldmle) {

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