scoutfs: minor manifest ring comparison tracing

It was nice to watch the ring compare nodes so leave behind the trace
and clean up the callers so that uninitialized keys are cleanly null.

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

kmod/src/manifest.c

@@ -414,6 +414,7 @@ scoutfs_manifest_find_range_entries(struct super_block *sb,
 	nr = 0;
 
 	/* get level 0 segments that overlap with the missing range */
+	skey.key = NULL;
 	skey.level = 0;
 	skey.seq = ~0ULL;
 	ment = scoutfs_ring_lookup_prev(&mani->ring, &skey);
@@ -836,6 +837,8 @@ static int manifest_ring_compare_key(void *key, void *data)
 	struct scoutfs_key_buf last;
 	int cmp;
 
+	scoutfs_key_init(&first, NULL, 0);
+
 	if (skey->level < ment->level) {
 		cmp = -1;
 		goto out;
@@ -861,6 +864,13 @@ static int manifest_ring_compare_key(void *key, void *data)
 	}
 
 out:
+#if 0
+	/* pretty expensive to be on by default */
+	SK_TRACE_PRINTK("%u,%llu,"SK_FMT" %c %u,%llu,"SK_FMT"\n",
+			skey->level, skey->seq, SK_ARG(skey->key),
+			cmp < 0 ? '<' : cmp == 0 ? '=' : '>',
+			ment->level, le64_to_cpu(ment->seq), SK_ARG(&first));
+#endif
 	return cmp;
 }