dlm: use rwlock for lkbidr

Convert the lock for lkbidr to an rwlock.  Most idr lookups will use
the read lock.

Signed-off-by: Alexander Aring <[email protected]>
Signed-off-by: David Teigland <[email protected]>

Author: Alexander Aring

fs/dlm/dlm_internal.h

@@ -582,7 +582,7 @@ struct dlm_ls {
 	struct kobject		ls_kobj;
 
 	struct idr		ls_lkbidr;
-	spinlock_t		ls_lkbidr_spin;
+	rwlock_t		ls_lkbidr_lock;
 
 	struct rhashtable	ls_rsbtbl;
 	rwlock_t		ls_rsbtbl_lock;

fs/dlm/lock.c

@@ -1522,11 +1522,11 @@ static int _create_lkb(struct dlm_ls *ls, struct dlm_lkb **lkb_ret,
 	INIT_LIST_HEAD(&lkb->lkb_ownqueue);
 	INIT_LIST_HEAD(&lkb->lkb_rsb_lookup);
 
-	spin_lock_bh(&ls->ls_lkbidr_spin);
+	write_lock_bh(&ls->ls_lkbidr_lock);
 	rv = idr_alloc(&ls->ls_lkbidr, lkb, start, end, GFP_NOWAIT);
 	if (rv >= 0)
 		lkb->lkb_id = rv;
-	spin_unlock_bh(&ls->ls_lkbidr_spin);
+	write_unlock_bh(&ls->ls_lkbidr_lock);
 
 	if (rv < 0) {
 		log_error(ls, "create_lkb idr error %d", rv);
@@ -1547,11 +1547,11 @@ static int find_lkb(struct dlm_ls *ls, uint32_t lkid, struct dlm_lkb **lkb_ret)
 {
 	struct dlm_lkb *lkb;
 
-	spin_lock_bh(&ls->ls_lkbidr_spin);
+	read_lock_bh(&ls->ls_lkbidr_lock);
 	lkb = idr_find(&ls->ls_lkbidr, lkid);
 	if (lkb)
 		kref_get(&lkb->lkb_ref);
-	spin_unlock_bh(&ls->ls_lkbidr_spin);
+	read_unlock_bh(&ls->ls_lkbidr_lock);
 
 	*lkb_ret = lkb;
 	return lkb ? 0 : -ENOENT;
@@ -1567,36 +1567,6 @@ static void kill_lkb(struct kref *kref)
 	DLM_ASSERT(!lkb->lkb_status, dlm_print_lkb(lkb););
 }
 
-/* TODO move this to lib/refcount.c */
-static __must_check bool
-dlm_refcount_dec_and_lock_bh(refcount_t *r, spinlock_t *lock)
-__cond_acquires(lock)
-{
-	if (refcount_dec_not_one(r))
-		return false;
-
-	spin_lock_bh(lock);
-	if (!refcount_dec_and_test(r)) {
-		spin_unlock_bh(lock);
-		return false;
-	}
-
-	return true;
-}
-
-/* TODO move this to include/linux/kref.h */
-static inline int dlm_kref_put_lock_bh(struct kref *kref,
-				       void (*release)(struct kref *kref),
-				       spinlock_t *lock)
-{
-	if (dlm_refcount_dec_and_lock_bh(&kref->refcount, lock)) {
-		release(kref);
-		return 1;
-	}
-
-	return 0;
-}
-
 /* __put_lkb() is used when an lkb may not have an rsb attached to
    it so we need to provide the lockspace explicitly */
 
@@ -1605,11 +1575,11 @@ static int __put_lkb(struct dlm_ls *ls, struct dlm_lkb *lkb)
 	uint32_t lkid = lkb->lkb_id;
 	int rv;
 
-	rv = dlm_kref_put_lock_bh(&lkb->lkb_ref, kill_lkb,
-				  &ls->ls_lkbidr_spin);
+	rv = dlm_kref_put_write_lock_bh(&lkb->lkb_ref, kill_lkb,
+					&ls->ls_lkbidr_lock);
 	if (rv) {
 		idr_remove(&ls->ls_lkbidr, lkid);
-		spin_unlock_bh(&ls->ls_lkbidr_spin);
+		write_unlock_bh(&ls->ls_lkbidr_lock);
 
 		detach_lkb(lkb);
 

fs/dlm/lockspace.c

@@ -431,7 +431,7 @@ static int new_lockspace(const char *name, const char *cluster,
 		goto out_lsfree;
 
 	idr_init(&ls->ls_lkbidr);
-	spin_lock_init(&ls->ls_lkbidr_spin);
+	rwlock_init(&ls->ls_lkbidr_lock);
 
 	INIT_LIST_HEAD(&ls->ls_waiters);
 	spin_lock_init(&ls->ls_waiters_lock);
@@ -676,15 +676,15 @@ static int lockspace_busy(struct dlm_ls *ls, int force)
 {
 	int rv;
 
-	spin_lock_bh(&ls->ls_lkbidr_spin);
+	read_lock_bh(&ls->ls_lkbidr_lock);
 	if (force == 0) {
 		rv = idr_for_each(&ls->ls_lkbidr, lkb_idr_is_any, ls);
 	} else if (force == 1) {
 		rv = idr_for_each(&ls->ls_lkbidr, lkb_idr_is_local, ls);
 	} else {
 		rv = 0;
 	}
-	spin_unlock_bh(&ls->ls_lkbidr_spin);
+	read_unlock_bh(&ls->ls_lkbidr_lock);
 	return rv;
 }