libbdev: extended version

This version of libbdev support asynchronous communication, recovery after driver restarts, and retrying of failed transfer operations.
2011-12-05 16:28:09 +01:00
parent 9221586f37
commit ed007ca416
11 changed files with 989 additions and 55 deletions
@@ -0,0 +1,120 @@
+/* libbdev - tracking and reopening of opened minor devices */
+
+#include <minix/drivers.h>
+#include <minix/bdev.h>
+#include <assert.h>
+
+#include "const.h"
+#include "type.h"
+#include "proto.h"
+
+static struct {
+  dev_t dev;
+  int count;
+  int access;
+} open_dev[NR_OPEN_DEVS] = { { NO_DEV, 0, 0 } };
+
+int bdev_minor_reopen(dev_t dev)
+{
+/* Reopen all minor devices on a major device. This function duplicates some
+ * code from elsewhere, because in this case we must avoid performing recovery.
+ * FIXME: if reopening fails with a non-IPC error, we should attempt to close
+ * all minors that we did manage to reopen so far, or they might stay open
+ * forever.
+ */
+  endpoint_t endpt;
+  message m;
+  int i, j, r, major;
+
+  major = major(dev);
+  endpt = bdev_driver_get(dev);
+
+  assert(endpt != NONE);
+
+  for (i = 0; i < NR_OPEN_DEVS; i++) {
+	if (major(open_dev[i].dev) != major)
+		continue;
+
+	/* Each minor device may have been opened multiple times. Send an open
+	 * request for each time that it was opened before. We could reopen it
+	 * just once, but then we'd have to keep a shadow open count as well.
+	 */
+	for (j = 0; j < open_dev[i].count; j++) {
+		memset(&m, 0, sizeof(m));
+		m.m_type = BDEV_OPEN;
+		m.BDEV_MINOR = minor(open_dev[i].dev);
+		m.BDEV_ACCESS = open_dev[i].access;
+		m.BDEV_ID = NO_ID;
+
+		if ((r = sendrec(endpt, &m)) != OK) {
+			printf("bdev: IPC to driver (%d) failed (%d)\n",
+				endpt, r);
+			return r;
+		}
+
+		if (m.m_type != BDEV_REPLY) {
+			printf("bdev: driver (%d) sent weird response (%d)\n",
+				endpt, m.m_type);
+			return EINVAL;
+		}
+
+		if (m.BDEV_ID != NO_ID) {
+			printf("bdev: driver (%d) sent invalid ID (%ld)\n",
+				endpt, m.BDEV_ID);
+			return EINVAL;
+		}
+
+		if ((r = m.BDEV_STATUS) != OK) {
+			printf("bdev: driver (%d) failed device reopen (%d)\n",
+				endpt, r);
+			return r;
+		}
+	}
+  }
+
+  return OK;
+}
+
+void bdev_minor_add(dev_t dev, int access)
+{
+/* Increase the reference count of the given minor device.
+ */
+  int i, free = -1;
+
+  for (i = 0; i < NR_OPEN_DEVS; i++) {
+	if (open_dev[i].dev == dev) {
+		open_dev[i].count++;
+		open_dev[i].access |= access;
+
+		return;
+	}
+
+	if (free < 0 && open_dev[i].dev == NO_DEV)
+		free = i;
+  }
+
+  if (free < 0) {
+	printf("bdev: too many open devices, increase NR_OPEN_DEVS\n");
+	return;
+  }
+
+  open_dev[free].dev = dev;
+  open_dev[free].count = 1;
+  open_dev[free].access = access;
+}
+
+void bdev_minor_del(dev_t dev)
+{
+/* Decrease the reference count of the given minor device, if present.
+ */
+  int i;
+
+  for (i = 0; i < NR_OPEN_DEVS; i++) {
+	if (open_dev[i].dev == dev) {
+		if (!--open_dev[i].count)
+			open_dev[i].dev = NO_DEV;
+
+		break;
+	}
+  }
+}