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Commit 7beaf243 authored by Srinivas Eeda's avatar Srinivas Eeda Committed by Joel Becker
Browse files

ocfs2 fix o2dlm dlm run purgelist (rev 3) 



This patch fixes two problems in dlm_run_purgelist

1. If a lockres is found to be in use, dlm_run_purgelist keeps trying to purge
the same lockres instead of trying the next lockres.

2. When a lockres is found unused, dlm_run_purgelist releases lockres spinlock
before setting DLM_LOCK_RES_DROPPING_REF and calls dlm_purge_lockres.
spinlock is reacquired but in this window lockres can get reused. This leads
to BUG.

This patch modifies dlm_run_purgelist to skip lockres if it's in use and purge
 next lockres. It also sets DLM_LOCK_RES_DROPPING_REF before releasing the
lockres spinlock protecting it from getting reused.

Signed-off-by: default avatarSrinivas Eeda <srinivas.eeda@oracle.com>
Acked-by: default avatarSunil Mushran <sunil.mushran@oracle.com>
Cc: stable@kernel.org
Signed-off-by: default avatarJoel Becker <joel.becker@oracle.com>
parent 6d98c3cc

fs/ocfs2/dlm/dlmthread.c

+34 −46
Original line number Original line Diff line number Diff line
@@ -152,45 +152,25 @@ void dlm_lockres_calc_usage(struct dlm_ctxt *dlm, 
	spin_unlock(&dlm->spinlock);

	spin_unlock(&dlm->spinlock);

}

}





static int dlm_purge_lockres(struct dlm_ctxt *dlm,

static void dlm_purge_lockres(struct dlm_ctxt *dlm,

			     struct dlm_lock_resource *res)

			     struct dlm_lock_resource *res)

{

{

	int master;

	int master;

	int ret = 0;

	int ret = 0;





	spin_lock(&res->spinlock);

	assert_spin_locked(&dlm->spinlock);

	if (!__dlm_lockres_unused(res)) {

	assert_spin_locked(&res->spinlock);

		mlog(0, "%s:%.*s: tried to purge but not unused\n",

		     dlm->name, res->lockname.len, res->lockname.name);

		__dlm_print_one_lock_resource(res);

		spin_unlock(&res->spinlock);

		BUG();

	}



	if (res->state & DLM_LOCK_RES_MIGRATING) {

		mlog(0, "%s:%.*s: Delay dropref as this lockres is "

		     "being remastered\n", dlm->name, res->lockname.len,

		     res->lockname.name);

		/* Re-add the lockres to the end of the purge list */

		if (!list_empty(&res->purge)) {

			list_del_init(&res->purge);

			list_add_tail(&res->purge, &dlm->purge_list);

		}

		spin_unlock(&res->spinlock);

		return 0;

	}





	master = (res->owner == dlm->node_num);

	master = (res->owner == dlm->node_num);





	if (!master)

		res->state |= DLM_LOCK_RES_DROPPING_REF;

	spin_unlock(&res->spinlock);





	mlog(0, "purging lockres %.*s, master = %d\n", res->lockname.len,

	mlog(0, "purging lockres %.*s, master = %d\n", res->lockname.len,

	     res->lockname.name, master);

	     res->lockname.name, master);





	if (!master) {

	if (!master) {

		res->state |= DLM_LOCK_RES_DROPPING_REF;

		/* drop spinlock...  retake below */

		/* drop spinlock...  retake below */

		spin_unlock(&res->spinlock);

		spin_unlock(&dlm->spinlock);

		spin_unlock(&dlm->spinlock);





		spin_lock(&res->spinlock);

		spin_lock(&res->spinlock);
@@ -208,31 +188,35 @@ static int dlm_purge_lockres(struct dlm_ctxt *dlm, 
		mlog(0, "%s:%.*s: dlm_deref_lockres returned %d\n",

		mlog(0, "%s:%.*s: dlm_deref_lockres returned %d\n",

		     dlm->name, res->lockname.len, res->lockname.name, ret);

		     dlm->name, res->lockname.len, res->lockname.name, ret);

		spin_lock(&dlm->spinlock);

		spin_lock(&dlm->spinlock);

		spin_lock(&res->spinlock);

	}

	}





	spin_lock(&res->spinlock);

	if (!list_empty(&res->purge)) {

	if (!list_empty(&res->purge)) {

		mlog(0, "removing lockres %.*s:%p from purgelist, "

		mlog(0, "removing lockres %.*s:%p from purgelist, "

		     "master = %d\n", res->lockname.len, res->lockname.name,

		     "master = %d\n", res->lockname.len, res->lockname.name,

		     res, master);

		     res, master);

		list_del_init(&res->purge);

		list_del_init(&res->purge);

		spin_unlock(&res->spinlock);

		dlm_lockres_put(res);

		dlm_lockres_put(res);

		dlm->purge_count--;

		dlm->purge_count--;

	} else

	}

		spin_unlock(&res->spinlock);



	if (!__dlm_lockres_unused(res)) {

		mlog(ML_ERROR, "found lockres %s:%.*s: in use after deref\n",

		     dlm->name, res->lockname.len, res->lockname.name);

		__dlm_print_one_lock_resource(res);

		BUG();

	}





	__dlm_unhash_lockres(res);

	__dlm_unhash_lockres(res);





	/* lockres is not in the hash now.  drop the flag and wake up

	/* lockres is not in the hash now.  drop the flag and wake up

	 * any processes waiting in dlm_get_lock_resource. */

	 * any processes waiting in dlm_get_lock_resource. */

	if (!master) {

	if (!master) {

		spin_lock(&res->spinlock);

		res->state &= ~DLM_LOCK_RES_DROPPING_REF;

		res->state &= ~DLM_LOCK_RES_DROPPING_REF;

		spin_unlock(&res->spinlock);

		spin_unlock(&res->spinlock);

		wake_up(&res->wq);

		wake_up(&res->wq);

	}

	} else

	return 0;

		spin_unlock(&res->spinlock);

}

}





static void dlm_run_purge_list(struct dlm_ctxt *dlm,

static void dlm_run_purge_list(struct dlm_ctxt *dlm,
@@ -251,17 +235,7 @@ static void dlm_run_purge_list(struct dlm_ctxt *dlm, 
		lockres = list_entry(dlm->purge_list.next,

		lockres = list_entry(dlm->purge_list.next,

				     struct dlm_lock_resource, purge);

				     struct dlm_lock_resource, purge);





		/* Status of the lockres *might* change so double

		 * check. If the lockres is unused, holding the dlm

		 * spinlock will prevent people from getting and more

		 * refs on it -- there's no need to keep the lockres

		 * spinlock. */

		spin_lock(&lockres->spinlock);

		spin_lock(&lockres->spinlock);

		unused = __dlm_lockres_unused(lockres);

		spin_unlock(&lockres->spinlock);



		if (!unused)

			continue;





		purge_jiffies = lockres->last_used +

		purge_jiffies = lockres->last_used +

			msecs_to_jiffies(DLM_PURGE_INTERVAL_MS);

			msecs_to_jiffies(DLM_PURGE_INTERVAL_MS);
@@ -273,15 +247,29 @@ static void dlm_run_purge_list(struct dlm_ctxt *dlm, 
			 * in tail order, we can stop at the first

			 * in tail order, we can stop at the first

			 * unpurgable resource -- anyone added after

			 * unpurgable resource -- anyone added after

			 * him will have a greater last_used value */

			 * him will have a greater last_used value */

			spin_unlock(&lockres->spinlock);

			break;

			break;

		}

		}





		/* Status of the lockres *might* change so double

		 * check. If the lockres is unused, holding the dlm

		 * spinlock will prevent people from getting and more

		 * refs on it. */

		unused = __dlm_lockres_unused(lockres);

		if (!unused ||

		    (lockres->state & DLM_LOCK_RES_MIGRATING)) {

			mlog(0, "lockres %s:%.*s: is in use or "

			     "being remastered, used %d, state %d\n",

			     dlm->name, lockres->lockname.len,

			     lockres->lockname.name, !unused, lockres->state);

			list_move_tail(&dlm->purge_list, &lockres->purge);

			spin_unlock(&lockres->spinlock);

			continue;

		}



		dlm_lockres_get(lockres);

		dlm_lockres_get(lockres);





		/* This may drop and reacquire the dlm spinlock if it

		dlm_purge_lockres(dlm, lockres);

		 * has to do migration. */

		if (dlm_purge_lockres(dlm, lockres))

			BUG();





		dlm_lockres_put(lockres);

		dlm_lockres_put(lockres);