sunrpc: Fix potential leaks in sunrpc_cache_unhash()

mainline inclusion
from mainline-v5.6-rc1
commit 1d821637
category: bugfix
bugzilla: 51810
CVE: NA

-------------------------------------------------

When we unhash the cache entry, we need to handle any pending upcalls
by calling cache_fresh_unlocked().
Signed-off-by: NTrond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>
Signed-off-by: NLu Wei <luwei32@huawei.com>
Reviewed-by: NYue Haibing <yuehaibing@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

net/sunrpc/cache.c

@@ -1855,7 +1855,9 @@ void sunrpc_cache_unhash(struct cache_detail *cd, struct cache_head *h)
 	if (!hlist_unhashed(&h->cache_list)){
 		hlist_del_init(&h->cache_list);
 		cd->entries--;
+		set_bit(CACHE_CLEANED, &h->flags);
 		write_unlock(&cd->hash_lock);
+		cache_fresh_unlocked(h, cd);
 		cache_put(h, cd);
 	} else
 		write_unlock(&cd->hash_lock);