thrpool: add comment explaining minimum thread count

I forgot why this bound was necessary, so add a comment
ensuring I do not forget again.

1 files changed, 2 insertions, 0 deletions

diff --git a/thrpool.c b/thrpool.c
index 3bff31e..cf1afba 100644
--- a/thrpool.c
+++ b/thrpool.c
@@ -214,8 +214,10 @@ void
 mog_thrpool_start(struct mog_thrpool *tp, size_t n,
                   void *(*start_fn)(void *), void *arg)
 {
+        /* we may be started on a new server before device dirs exist */
         if (n == 0)
                 n = 1;
+
         tp->threads = NULL;
         tp->n_threads = 0;
         tp->start_fn = start_fn;