drbd: fix race on meta-data update, addendum

[net-next-2.6.git] / drivers / block / drbd / drbd_main.c

diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 5dd071e5c921ba1a03f967c6145d749a55d9ece8..ab1244e0045c497aba01c5cf267483c14f584cfe 100644 (file)
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -3402,9 +3402,10 @@ void drbd_md_sync(struct drbd_conf *mdev)
        sector_t sector;
        int i;
 
+       del_timer(&mdev->md_sync_timer);
+       /* timer may be rearmed by drbd_md_mark_dirty() now. */
        if (!test_and_clear_bit(MD_DIRTY, &mdev->flags))
                return;
-       del_timer(&mdev->md_sync_timer);
 
        /* We use here D_FAILED and not D_ATTACHING because we try to write
         * metadata even if we detach due to a disk failure! */
@@ -3529,12 +3530,22 @@ int drbd_md_read(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
  * the meta-data super block. This function sets MD_DIRTY, and starts a
  * timer that ensures that within five seconds you have to call drbd_md_sync().
  */
+#ifdef DRBD_DEBUG_MD_SYNC
+void drbd_md_mark_dirty_(struct drbd_conf *mdev, unsigned int line, const char *func)
+{
+       if (!test_and_set_bit(MD_DIRTY, &mdev->flags)) {
+               mod_timer(&mdev->md_sync_timer, jiffies + HZ);
+               mdev->last_md_mark_dirty.line = line;
+               mdev->last_md_mark_dirty.func = func;
+       }
+}
+#else
 void drbd_md_mark_dirty(struct drbd_conf *mdev)
 {
-       set_bit(MD_DIRTY, &mdev->flags);
-       mod_timer(&mdev->md_sync_timer, jiffies + 5*HZ);
+       if (!test_and_set_bit(MD_DIRTY, &mdev->flags))
+               mod_timer(&mdev->md_sync_timer, jiffies + HZ);
 }
-
+#endif
 
 static void drbd_uuid_move_history(struct drbd_conf *mdev) __must_hold(local)
 {
@@ -3775,8 +3786,11 @@ static void md_sync_timer_fn(unsigned long data)
 static int w_md_sync(struct drbd_conf *mdev, struct drbd_work *w, int unused)
 {
        dev_warn(DEV, "md_sync_timer expired! Worker calls drbd_md_sync().\n");
+#ifdef DEBUG
+       dev_warn(DEV, "last md_mark_dirty: %s:%u\n",
+               mdev->last_md_mark_dirty.func, mdev->last_md_mark_dirty.line);
+#endif
        drbd_md_sync(mdev);
-
        return 1;
 }