Don't respond with ENOENT for no srch compaction

The srch compaction request building function and the srch compaction
worker both have logic to recognize a valid response with no input files
indicating that there's no work to do.  The server unfortunately
translated nr == 0 into ENOENT and send that error response to the
client.  This caused the client to increment error counters in the
common case when there's no compaction work to perform.  We'd like the
error counter to reflect actual errors, we're about to check it in a
test, so let's fix this up to the server sends a sucessful response with
nr == 0 to indicate that there's no work to do.

Signed-off-by: Zach Brown <zab@versity.com>

kmod/src/server.c

@@ -1966,9 +1966,7 @@ static int server_srch_get_compact(struct super_block *sb,
 	ret = scoutfs_srch_get_compact(sb, &server->alloc, &server->wri,
 				       &super->srch_root, rid, sc);
 	mutex_unlock(&server->srch_mutex);
-	if (ret == 0 && sc->nr == 0)
-		ret = -ENOENT;
-	if (ret < 0)
+	if (ret < 0 || (ret == 0 && sc->nr == 0))
 		goto apply;
 
 	mutex_lock(&server->alloc_mutex);

kmod/src/srch.c

@@ -2179,7 +2179,7 @@ out:
 
 	scoutfs_block_writer_forget_all(sb, &wri);
 	if (!atomic_read(&srinf->shutdown)) {
-		delay = ret == 0 ? 0 : msecs_to_jiffies(SRCH_COMPACT_DELAY_MS);
+		delay = (sc->nr > 0 && ret == 0) ? 0 : msecs_to_jiffies(SRCH_COMPACT_DELAY_MS);
 		queue_delayed_work(srinf->workq, &srinf->compact_dwork, delay);
 	}