Commit 3f3a9b84 authored Sep 01, 2010 by Lars Ellenberg Committed by Philipp Reisner Oct 14, 2010

drbd: fix race on meta-data update



The race:
	drbd_md_mark_dirty()
	drbd_md_sync()
		if (!test_and_clear_bit(MD_DIRTY, &mdev->flags))
			return;
		drbd_md_sync_page_io(mdev, mdev->ldev, sector, WRITE)
  ==> RACE
		clear_bit(MD_DIRTY, &mdev->flags); <== spurious

Fixed by removing the spurious clear_bit.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

parent c518d04f

drivers/block/drbd/drbd_main.c

+1 −4

Original line number	Diff line number	Diff line
		@@ -3446,12 +3446,9 @@ void drbd_md_sync(struct drbd_conf *mdev)
		D_ASSERT(drbd_md_ss__(mdev, mdev->ldev) == mdev->ldev->md.md_offset);
		sector = mdev->ldev->md.md_offset;

		if (drbd_md_sync_page_io(mdev, mdev->ldev, sector, WRITE)) {
		clear_bit(MD_DIRTY, &mdev->flags);
		} else {
		if (!drbd_md_sync_page_io(mdev, mdev->ldev, sector, WRITE)) {
		/* this was a try anyways ... */
		dev_err(DEV, "meta data update failed!\n");

		drbd_chk_io_error(mdev, 1, TRUE);
		}