Commit 6fc4e354 authored by Sage Weil's avatar Sage Weil Committed by Chris Mason
Browse files

Btrfs: pass lockdep rwsem metadata to async commit transaction 



The freeze rwsem is taken by sb_start_intwrite() and dropped during the
commit_ or end_transaction().  In the async case, that happens in a worker
thread.  Tell lockdep the calling thread is releasing ownership of the
rwsem and the async thread is picking it up.

XFS plays the same trick in fs/xfs/xfs_aops.c.

Signed-off-by: default avatarSage Weil <sage@inktank.com>
parent 2aaa6655

fs/btrfs/transaction.c

+16 −0
Original line number Diff line number Diff line
@@ -1229,6 +1229,14 @@ static void do_async_commit(struct work_struct *work) 
	struct btrfs_async_commit *ac =

		container_of(work, struct btrfs_async_commit, work.work);



	/*

	 * We've got freeze protection passed with the transaction.

	 * Tell lockdep about it.

	 */

	rwsem_acquire_read(

		&ac->root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1],

		0, 1, _THIS_IP_);



	btrfs_commit_transaction(ac->newtrans, ac->root);

	kfree(ac);

}
@@ -1258,6 +1266,14 @@ int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans, 
	atomic_inc(&cur_trans->use_count);



	btrfs_end_transaction(trans, root);



	/*

	 * Tell lockdep we've released the freeze rwsem, since the

	 * async commit thread will be the one to unlock it.

	 */

	rwsem_release(&root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1],

		      1, _THIS_IP_);



	schedule_delayed_work(&ac->work, 0);



	/* wait for transaction to start and unblock */