cachefiles: avoid pointless cred reference count bump

The cache holds a long-term reference to the credentials that's taken
when the cache is created and put when the cache becomes unused.

Link: https://lore.kernel.org/r/20241125-work-cred-v2-27-68b9d38bb5b2@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Christian Brauner <brauner@kernel.org>

Author: brauner

fs/cachefiles/internal.h

@@ -393,13 +393,13 @@ extern int cachefiles_determine_cache_security(struct cachefiles_cache *cache,
 static inline void cachefiles_begin_secure(struct cachefiles_cache *cache,
 					   const struct cred **_saved_cred)
 {
-	*_saved_cred = override_creds(get_new_cred(cache->cache_cred));
+	*_saved_cred = override_creds(cache->cache_cred);
 }
 
 static inline void cachefiles_end_secure(struct cachefiles_cache *cache,
 					 const struct cred *saved_cred)
 {
-	put_cred(revert_creds(saved_cred));
+	revert_creds(saved_cred);
 }
 
 /*