Commit d9ef7522 authored by Wengang Wang's avatar Wengang Wang Committed by Joel Becker
Browse files

ocfs2:dlm: avoid dlm->ast_lock lockres->spinlock dependency break 



Currently we process a dirty lockres with the lockres->spinlock taken. While
during the process, we may need to lock on dlm->ast_lock. This breaks the
dependency of dlm->ast_lock(lock first) and lockres->spinlock(lock second).

This patch fixes the problem.
Since we can't release lockres->spinlock, we have to take dlm->ast_lock
just before taking the lockres->spinlock and release it after lockres->spinlock
is released. And use __dlm_queue_bast()/__dlm_queue_ast(), the nolock version,
in dlm_shuffle_lists(). There are no too many locks on a lockres, so there is no
performance harm.

Signed-off-by: default avatarWengang Wang <wen.gang.wang@oracle.com>
Signed-off-by: default avatarJoel Becker <joel.becker@oracle.com>
parent d5a7df06

fs/ocfs2/dlm/dlmast.c

+2 −2
Original line number Diff line number Diff line
@@ -89,7 +89,7 @@ static int dlm_should_cancel_bast(struct dlm_ctxt *dlm, struct dlm_lock *lock) 
	return 0;

}



static void __dlm_queue_ast(struct dlm_ctxt *dlm, struct dlm_lock *lock)

void __dlm_queue_ast(struct dlm_ctxt *dlm, struct dlm_lock *lock)

{

	mlog_entry_void();
@@ -146,7 +146,7 @@ void dlm_queue_ast(struct dlm_ctxt *dlm, struct dlm_lock *lock) 
}





static void __dlm_queue_bast(struct dlm_ctxt *dlm, struct dlm_lock *lock)

void __dlm_queue_bast(struct dlm_ctxt *dlm, struct dlm_lock *lock)

{

	mlog_entry_void();

fs/ocfs2/dlm/dlmcommon.h

+2 −0
Original line number Diff line number Diff line
@@ -904,6 +904,8 @@ void __dlm_lockres_grab_inflight_ref(struct dlm_ctxt *dlm, 


void dlm_queue_ast(struct dlm_ctxt *dlm, struct dlm_lock *lock);

void dlm_queue_bast(struct dlm_ctxt *dlm, struct dlm_lock *lock);

void __dlm_queue_ast(struct dlm_ctxt *dlm, struct dlm_lock *lock);

void __dlm_queue_bast(struct dlm_ctxt *dlm, struct dlm_lock *lock);

void dlm_do_local_ast(struct dlm_ctxt *dlm,

		      struct dlm_lock_resource *res,

		      struct dlm_lock *lock);

fs/ocfs2/dlm/dlmthread.c

+10 −6
Original line number Diff line number Diff line
@@ -310,6 +310,7 @@ static void dlm_shuffle_lists(struct dlm_ctxt *dlm, 
	 * spinlock, and because we know that it is not migrating/

	 * recovering/in-progress, it is fine to reserve asts and

	 * basts right before queueing them all throughout */

	assert_spin_locked(&dlm->ast_lock);

	assert_spin_locked(&res->spinlock);

	BUG_ON((res->state & (DLM_LOCK_RES_MIGRATING|

			      DLM_LOCK_RES_RECOVERING|
@@ -338,7 +339,7 @@ converting: 
			/* queue the BAST if not already */

			if (lock->ml.highest_blocked == LKM_IVMODE) {

				__dlm_lockres_reserve_ast(res);

				dlm_queue_bast(dlm, lock);

				__dlm_queue_bast(dlm, lock);

			}

			/* update the highest_blocked if needed */

			if (lock->ml.highest_blocked < target->ml.convert_type)
@@ -356,7 +357,7 @@ converting: 
			can_grant = 0;

			if (lock->ml.highest_blocked == LKM_IVMODE) {

				__dlm_lockres_reserve_ast(res);

				dlm_queue_bast(dlm, lock);

				__dlm_queue_bast(dlm, lock);

			}

			if (lock->ml.highest_blocked < target->ml.convert_type)

				lock->ml.highest_blocked =
@@ -384,7 +385,7 @@ converting: 
		spin_unlock(&target->spinlock);



		__dlm_lockres_reserve_ast(res);

		dlm_queue_ast(dlm, target);

		__dlm_queue_ast(dlm, target);

		/* go back and check for more */

		goto converting;

	}
@@ -403,7 +404,7 @@ blocked: 
			can_grant = 0;

			if (lock->ml.highest_blocked == LKM_IVMODE) {

				__dlm_lockres_reserve_ast(res);

				dlm_queue_bast(dlm, lock);

				__dlm_queue_bast(dlm, lock);

			}

			if (lock->ml.highest_blocked < target->ml.type)

				lock->ml.highest_blocked = target->ml.type;
@@ -419,7 +420,7 @@ blocked: 
			can_grant = 0;

			if (lock->ml.highest_blocked == LKM_IVMODE) {

				__dlm_lockres_reserve_ast(res);

				dlm_queue_bast(dlm, lock);

				__dlm_queue_bast(dlm, lock);

			}

			if (lock->ml.highest_blocked < target->ml.type)

				lock->ml.highest_blocked = target->ml.type;
@@ -445,7 +446,7 @@ blocked: 
		spin_unlock(&target->spinlock);



		__dlm_lockres_reserve_ast(res);

		dlm_queue_ast(dlm, target);

		__dlm_queue_ast(dlm, target);

		/* go back and check for more */

		goto converting;

	}
@@ -675,6 +676,7 @@ static int dlm_thread(void *data) 
		 	/* lockres can be re-dirtied/re-added to the

			 * dirty_list in this gap, but that is ok */



			spin_lock(&dlm->ast_lock);

			spin_lock(&res->spinlock);

			if (res->owner != dlm->node_num) {

				__dlm_print_one_lock_resource(res);
@@ -695,6 +697,7 @@ static int dlm_thread(void *data) 
				/* move it to the tail and keep going */

				res->state &= ~DLM_LOCK_RES_DIRTY;

				spin_unlock(&res->spinlock);

				spin_unlock(&dlm->ast_lock);

				mlog(0, "delaying list shuffling for in-"

				     "progress lockres %.*s, state=%d\n",

				     res->lockname.len, res->lockname.name,
@@ -716,6 +719,7 @@ static int dlm_thread(void *data) 
			dlm_shuffle_lists(dlm, res);

			res->state &= ~DLM_LOCK_RES_DIRTY;

			spin_unlock(&res->spinlock);

			spin_unlock(&dlm->ast_lock);



			dlm_lockres_calc_usage(dlm, res);

CRA Git | Maintained and supported by SUSTech CRA and CCSE