Add softrandommap and --alloc-size options

The softrandommap job option allows fio to continue if it cannot
allocate from the smalloc backing for the random map. Or the user
can specify --alloc-size with a size larger than the default of 1024k
to increase the size of the shared allocation pool.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/smalloc.c b/smalloc.c
index fd0e9bd..5baf5a4 100644
--- a/smalloc.c
+++ b/smalloc.c
@@ -19,8 +19,10 @@
 #define INITIAL_SIZE	1048576	/* new pool size */
 #define MAX_POOLS	32	/* maximum number of pools to setup */
 
+unsigned int smalloc_pool_size = INITIAL_SIZE;
+
 #ifdef ENABLE_RESIZE
-#define MAX_SIZE	8 * INITIAL_SIZE
+#define MAX_SIZE	8 * smalloc_pool_size
 static unsigned int resize_error;
 #endif
 
@@ -229,7 +231,7 @@
 	if (fd < 0)
 		goto out_close;
 
-	pool->size = INITIAL_SIZE;
+	pool->size = smalloc_pool_size;
 	if (ftruncate(fd, pool->size) < 0)
 		goto out_unlink;