From 2c6278ed4ba8022e98a8893202aa91c4934b4830 Mon Sep 17 00:00:00 2001
From: Joe Thornber <ejt@redhat.com>
Date: Mon, 24 Jul 2017 15:35:10 +0100
Subject: [PATCH] [block_cache] Be better about flushing dirty blocks on
 demand.

Dirty blocks could prevent a clean lock being given.  Patch from mingus.
---
 block-cache/block_cache.cc | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/block-cache/block_cache.cc b/block-cache/block_cache.cc
index f276625..7f603c2 100644
--- a/block-cache/block_cache.cc
+++ b/block-cache/block_cache.cc
@@ -319,14 +319,13 @@ block_cache::new_block(block_address index)
 	block *b;
 
 	b = __alloc_block();
-	if (!b) {
-		if (clean_.empty()) {
+	while (!b && nr_locked_ < nr_cache_blocks_) {
+		b = find_unused_clean_block();
+		if (!b) {
 			if (io_pending_.empty())
 				writeback(16);
 			wait_io();
 		}
-
-		b = find_unused_clean_block();
 	}
 
 	if (b) {