unix_io.c (find_cached_block): Fixed bug which caused some clean
	blocks to be erroneously marked as dirty, so they would
	get written back to the disk before they are evicted from
	the cache.  Harmless, but it slows down e2fsck
	significantly.

diff --git a/lib/ext2fs/unix_io.c b/lib/ext2fs/unix_io.c
index e8cd880..1dcca4a 100644
--- a/lib/ext2fs/unix_io.c
+++ b/lib/ext2fs/unix_io.c
@@ -252,6 +252,7 @@
 				      cache->block, 1, cache->buf);
 	}
 	cache->in_use = 1;
+	cache->dirty = 0;
 	cache->block = block;
 	cache->access_time = ++data->access_time;
 	return cache;