.

buse.c

@@ -74,8 +74,8 @@ int buse_main(int argc, char *argv[], const struct buse_operations *aop, void *u
 
     (void) userdata;
 
-    assert(argc == 3);
-    dev_file = argv[2];
+    assert(argc == 2);
+    dev_file = argv[1];
 
     assert(!socketpair(AF_UNIX, SOCK_STREAM, 0, sp));
 
@@ -91,6 +91,7 @@ int buse_main(int argc, char *argv[], const struct buse_operations *aop, void *u
         sk = sp[1];
 
         assert(ioctl(nbd, NBD_SET_SOCK, sk) != -1);
+	assert(ioctl(nbd, NBD_SET_FLAGS, NBD_FLAG_SEND_TRIM) != -1);
         err = ioctl(nbd, NBD_DO_IT);
         fprintf(stderr, "nbd device terminated with code %d\n", err);
         if (err == -1)

buse.h

@@ -26,6 +26,14 @@ enum {
 	NBD_CMD_TRIM = 4
 };
 
+/* values for flags field */
+#define NBD_FLAG_HAS_FLAGS	(1 << 0)	/* Flags are there */
+#define NBD_FLAG_READ_ONLY	(1 << 1)	/* Device is read-only */
+#define NBD_FLAG_SEND_FLUSH	(1 << 2)	/* Send FLUSH */
+#define NBD_FLAG_SEND_FUA	(1 << 3)	/* Send FUA (Force Unit Access) */
+#define NBD_FLAG_ROTATIONAL	(1 << 4)	/* Use elevator algorithm - rotational media */
+#define NBD_FLAG_SEND_TRIM    (1 << 5) /* send trim/discard */
+
 /* Magic numbers */
 #define NBD_REQUEST_MAGIC 0x25609513
 #define NBD_REPLY_MAGIC 0x67446698

busexmp.c

@@ -8,32 +8,47 @@ static void *data;
 
 static int xmp_read(void *buf, u_int32_t len, u_int64_t offset)
 {
-    memcpy(buf, (char *)data + offset, len);
-    return 0;
+  fprintf(stderr, "R - %lu, %u\n", offset, len);
+  memcpy(buf, (char *)data + offset, len);
+  return 0;
 }
 
 static int xmp_write(const void *buf, u_int32_t len, u_int64_t offset)
 {
-    memcpy((char *)data + offset, buf, len);
-    return 0;
+  fprintf(stderr, "W - %lu, %u\n", offset, len);
+  memcpy((char *)data + offset, buf, len);
+  return 0;
 }
 
 static int xmp_disc()
 {
-    fprintf(stderr, "Received a disconnect request.\n");
-    return 0;
+  fprintf(stderr, "Received a disconnect request.\n");
+  return 0;
 }
 
+static int xmp_flush(){
+  fprintf(stderr, "F\n");
+  return 0;
+}
+
+static int xmp_trim(u_int64_t from, u_int32_t len){
+  fprintf(stderr, "T - %lu, %u\n", from, len);
+  return 0;
+}
+
+
 static struct buse_operations aop = {
-    .read = xmp_read,
-    .write = xmp_write,
-    .disc = xmp_disc,
-    .size = 128 * 1024 * 1024,
+  .read = xmp_read,
+  .write = xmp_write,
+  .disc = xmp_disc,
+  .trim = xmp_trim,
+  .flush = xmp_flush,
+  .size = 128 * 1024 * 1024,
 };
 
 int main(int argc, char *argv[])
 {
-    data = malloc(aop.size);
+  data = malloc(aop.size);
 
-    return buse_main(argc, argv, &aop, NULL);
+  return buse_main(argc, argv, &aop, NULL);
 }