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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>
This commit is contained in:
Lars Ellenberg 2010-09-01 15:12:12 +02:00 committed by Philipp Reisner
parent c518d04fde
commit 3f3a9b849d
1 changed files with 1 additions and 4 deletions
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5
drivers/block/drbd/drbd_main.c
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@ -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);
}