Add the test we used in lecture to creash the IDE system when the

locks were moved around.

Makefile

@@ -107,6 +107,7 @@ UPROGS=\
 	_mkdir\
 	_rm\
 	_sh\
+	_stressfs\
 	_usertests\
 	_wc\
 	_zombie\

stressfs.c

@@ -0,0 +1,38 @@
+// 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.  Spinning 40000 times demonstrated the bug
+// after about 5 runs of stressfs in QEMU on a 2.1GHz CPU.
+
+#include "types.h"
+#include "stat.h"
+#include "user.h"
+#include "fs.h"
+#include "fcntl.h"
+
+int
+main(int argc, char *argv[])
+{
+  int i;
+  printf(1, "stressfs starting\n");
+
+  for (i = 0; i < 4; i++) {
+    if (fork() > 0) {
+      break;
+    }
+  }
+
+  printf(1, "%d\n", i);
+
+  char path[] = "stressfs0";
+  path[8] += i;
+  int fd = open(path, O_CREATE | O_RDWR);
+  for (i = 0; i < 100; i++)
+    printf(fd, "%d\n", i);
+  close(fd);
+
+  wait();
+
+  exit();
+}