SUNRPC/cache: Allow garbage collection of invalid cache entries

If the cache entry never gets initialised, we want the garbage
collector to be able to evict it. Otherwise if the upcall daemon
fails to initialise the entry, we end up never expiring it.
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
[ cel: resolved a merge conflict ]
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

include/linux/sunrpc/cache.h

@@ -209,9 +209,6 @@ static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
 
 static inline bool cache_is_expired(struct cache_detail *detail, struct cache_head *h)
 {
-	if (!test_bit(CACHE_VALID, &h->flags))
-		return false;
-
 	return  (h->expiry_time < seconds_since_boot()) ||
 		(detail->flush_time >= h->last_refresh);
 }

net/sunrpc/cache.c

@@ -64,14 +64,15 @@ static struct cache_head *sunrpc_cache_find_rcu(struct cache_detail *detail,
 
 	rcu_read_lock();
 	hlist_for_each_entry_rcu(tmp, head, cache_list) {
-		if (detail->match(tmp, key)) {
-			if (cache_is_expired(detail, tmp))
+		if (!detail->match(tmp, key))
+			continue;
+		if (test_bit(CACHE_VALID, &tmp->flags) &&
+		    cache_is_expired(detail, tmp))
 			continue;
 		tmp = cache_get_rcu(tmp);
 		rcu_read_unlock();
 		return tmp;
 	}
-	}
 	rcu_read_unlock();
 	return NULL;
 }
@@ -114,8 +115,10 @@ static struct cache_head *sunrpc_cache_add_entry(struct cache_detail *detail,
 	/* check if entry appeared while we slept */
 	hlist_for_each_entry_rcu(tmp, head, cache_list,
 				 lockdep_is_held(&detail->hash_lock)) {
-		if (detail->match(tmp, key)) {
-			if (cache_is_expired(detail, tmp)) {
+		if (!detail->match(tmp, key))
+			continue;
+		if (test_bit(CACHE_VALID, &tmp->flags) &&
+		    cache_is_expired(detail, tmp)) {
 			sunrpc_begin_cache_remove_entry(tmp, detail);
 			freeme = tmp;
 			break;
@@ -125,7 +128,6 @@ static struct cache_head *sunrpc_cache_add_entry(struct cache_detail *detail,
 		cache_put(new, detail);
 		return tmp;
 	}
-	}
 
 	hlist_add_head_rcu(&new->cache_list, head);
 	detail->entries++;