[PATCH] Use posix_fallocate() to force file layout

Dunno how well this works on all filesystems, but at least it's
a good hint to send wrt fragmentation and layout.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/filesetup.c b/filesetup.c
index 52d822a..0b95640 100644
--- a/filesetup.c
+++ b/filesetup.c
@@ -44,6 +44,11 @@
 		goto err;
 	}
 
+	if (posix_fallocate(f->fd, 0, f->file_size) < 0) {
+		td_verror(td, errno);
+		goto err;
+	}
+
 	b = malloc(td->max_bs);
 	memset(b, 0, td->max_bs);