--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/usr/stressfs.c	Fri May 26 23:11:05 2017 +0900
@@ -0,0 +1,49 @@
+// Demonstrate that moving the "acquire" in iderw after the loop that
+// appends to the idequeue results in a race.
+
+// For this to work, you should also add a spin within iderw's
+// idequeue traversal loop.  Adding the following demonstrated a panic
+// after about 5 runs of stressfs in QEMU on a 2.1GHz CPU:
+//    for (i = 0; i < 40000; i++)
+//      asm volatile("");
+
+#include "types.h"
+#include "stat.h"
+#include "user.h"
+#include "fs.h"
+#include "fcntl.h"
+
+int
+main(int argc, char *argv[])
+{
+    int fd, i;
+    char path[] = "stressfs0";
+    char data[512];
+    
+    printf(1, "stressfs starting\n");
+    memset(data, 'a', sizeof(data));
+    
+    for(i = 0; i < 4; i++)
+        if(fork() > 0)
+            break;
+    
+    printf(1, "write %d\n", i);
+    
+    path[8] += i;
+    fd = open(path, O_CREATE | O_RDWR);
+    for(i = 0; i < 20; i++)
+        //    printf(fd, "%d\n", i);
+        write(fd, data, sizeof(data));
+    close(fd);
+    
+    printf(1, "read\n");
+    
+    fd = open(path, O_RDONLY);
+    for (i = 0; i < 20; i++)
+        read(fd, data, sizeof(data));
+    close(fd);
+    
+    wait();
+    
+    exit();
+}