NFSD: Mark filecache "down" if init fails

NeilBrown says:
> The handling of NFSD_FILE_CACHE_UP is strange.  nfsd_file_cache_init()
> sets it, but doesn't clear it on failure.  So if nfsd_file_cache_init()
> fails for some reason, nfsd_file_cache_shutdown() would still try to
> clean up if it was called.

Reported-by: NeilBrown <neilb@suse.de>
Fixes: c7b824c ("NFSD: Replace the "init once" mechanism")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/filecache.c

@@ -723,7 +723,7 @@ nfsd_file_cache_init(void)
 
 	ret = rhltable_init(&nfsd_file_rhltable, &nfsd_file_rhash_params);
 	if (ret)
-		return ret;
+		goto out;
 
 	ret = -ENOMEM;
 	nfsd_file_slab = KMEM_CACHE(nfsd_file, 0);
@@ -775,6 +775,8 @@ nfsd_file_cache_init(void)
 
 	INIT_DELAYED_WORK(&nfsd_filecache_laundrette, nfsd_file_gc_worker);
 out:
+	if (ret)
+		clear_bit(NFSD_FILE_CACHE_UP, &nfsd_file_flags);
 	return ret;
 out_notifier:
 	lease_unregister_notifier(&nfsd_file_lease_notifier);