Commit 75a7d601 authored by Alexander Aring's avatar Alexander Aring Committed by David Teigland
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fs: dlm: handle lkb wait count as atomic_t 



Currently the lkb_wait_count is locked by the rsb lock and it should be
fine to handle lkb_wait_count as non atomic_t value. However for the
overall process of reducing locking this patch converts it to an
atomic_t value.

Signed-off-by: default avatarAlexander Aring <aahringo@redhat.com>
Signed-off-by: default avatarDavid Teigland <teigland@redhat.com>
parent 07ee3867

fs/dlm/dlm_internal.h

+1 −1
Original line number Diff line number Diff line
@@ -246,7 +246,7 @@ struct dlm_lkb { 
	int8_t			lkb_highbast;	/* highest mode bast sent for */



	int8_t			lkb_wait_type;	/* type of reply waiting for */

	int8_t			lkb_wait_count;

	atomic_t		lkb_wait_count;

	int			lkb_wait_nodeid; /* for debugging */



	struct list_head	lkb_statequeue;	/* rsb g/c/w list */

fs/dlm/lock.c

+14 −18
Original line number Diff line number Diff line
@@ -1407,6 +1407,7 @@ static int add_to_waiters(struct dlm_lkb *lkb, int mstype, int to_nodeid) 
{

	struct dlm_ls *ls = lkb->lkb_resource->res_ls;

	int error = 0;

	int wc;



	mutex_lock(&ls->ls_waiters_mutex);
@@ -1428,20 +1429,17 @@ static int add_to_waiters(struct dlm_lkb *lkb, int mstype, int to_nodeid) 
			error = -EBUSY;

			goto out;

		}

		lkb->lkb_wait_count++;

		wc = atomic_inc_return(&lkb->lkb_wait_count);

		hold_lkb(lkb);



		log_debug(ls, "addwait %x cur %d overlap %d count %d f %x",

			  lkb->lkb_id, lkb->lkb_wait_type, mstype,

			  lkb->lkb_wait_count, dlm_iflags_val(lkb));

			  lkb->lkb_id, lkb->lkb_wait_type, mstype, wc,

			  dlm_iflags_val(lkb));

		goto out;

	}



	DLM_ASSERT(!lkb->lkb_wait_count,

		   dlm_print_lkb(lkb);

		   printk("wait_count %d\n", lkb->lkb_wait_count););



	lkb->lkb_wait_count++;

	wc = atomic_fetch_inc(&lkb->lkb_wait_count);

	DLM_ASSERT(!wc, dlm_print_lkb(lkb); printk("wait_count %d\n", wc););

	lkb->lkb_wait_type = mstype;

	lkb->lkb_wait_nodeid = to_nodeid; /* for debugging */

	hold_lkb(lkb);
@@ -1504,7 +1502,7 @@ static int _remove_from_waiters(struct dlm_lkb *lkb, int mstype, 
		log_debug(ls, "remwait %x convert_reply zap overlap_cancel",

			  lkb->lkb_id);

		lkb->lkb_wait_type = 0;

		lkb->lkb_wait_count--;

		atomic_dec(&lkb->lkb_wait_count);

		unhold_lkb(lkb);

		goto out_del;

	}
@@ -1531,16 +1529,15 @@ static int _remove_from_waiters(struct dlm_lkb *lkb, int mstype, 
	if (overlap_done && lkb->lkb_wait_type) {

		log_error(ls, "remwait error %x reply %d wait_type %d overlap",

			  lkb->lkb_id, mstype, lkb->lkb_wait_type);

		lkb->lkb_wait_count--;

		atomic_dec(&lkb->lkb_wait_count);

		unhold_lkb(lkb);

		lkb->lkb_wait_type = 0;

	}



	DLM_ASSERT(lkb->lkb_wait_count, dlm_print_lkb(lkb););

	DLM_ASSERT(atomic_read(&lkb->lkb_wait_count), dlm_print_lkb(lkb););



	clear_bit(DLM_IFL_RESEND_BIT, &lkb->lkb_iflags);

	lkb->lkb_wait_count--;

	if (!lkb->lkb_wait_count)

	if (atomic_dec_and_test(&lkb->lkb_wait_count))

		list_del_init(&lkb->lkb_wait_reply);

	unhold_lkb(lkb);

	return 0;
@@ -2669,7 +2666,7 @@ static int validate_lock_args(struct dlm_ls *ls, struct dlm_lkb *lkb, 
			goto out;



		/* lock not allowed if there's any op in progress */

		if (lkb->lkb_wait_type || lkb->lkb_wait_count)

		if (lkb->lkb_wait_type || atomic_read(&lkb->lkb_wait_count))

			goto out;



		if (is_overlap(lkb))
@@ -2731,7 +2728,7 @@ static int validate_unlock_args(struct dlm_lkb *lkb, struct dlm_args *args) 


	/* normal unlock not allowed if there's any op in progress */

	if (!(args->flags & (DLM_LKF_CANCEL | DLM_LKF_FORCEUNLOCK)) &&

	    (lkb->lkb_wait_type || lkb->lkb_wait_count))

	    (lkb->lkb_wait_type || atomic_read(&lkb->lkb_wait_count)))

		goto out;



	/* an lkb may be waiting for an rsb lookup to complete where the
@@ -5066,10 +5063,9 @@ int dlm_recover_waiters_post(struct dlm_ls *ls) 
		/* drop all wait_count references we still

		 * hold a reference for this iteration.

		 */

		while (lkb->lkb_wait_count) {

			lkb->lkb_wait_count--;

		while (!atomic_dec_and_test(&lkb->lkb_wait_count))

			unhold_lkb(lkb);

		}



		mutex_lock(&ls->ls_waiters_mutex);

		list_del_init(&lkb->lkb_wait_reply);

		mutex_unlock(&ls->ls_waiters_mutex);