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Commit 0f873eca authored by Chris Mason's avatar Chris Mason
Browse files

btrfs: fix deadlock in delayed_ref_async_start 



"Btrfs: track transid for delayed ref flushing" was deadlocking on
btrfs_attach_transaction because its not safe to call from the async
delayed ref start code.  This commit brings back btrfs_join_transaction
instead and checks for a blocked commit.

Signed-off-by: default avatarJosef Bacik <jbacik@fb.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
parent 31b9655f

fs/btrfs/extent-tree.c

+11 −9
Original line number Diff line number Diff line
@@ -2851,16 +2851,13 @@ static void delayed_ref_async_start(struct btrfs_work *work) 


	async = container_of(work, struct async_delayed_refs, work);



	trans = btrfs_attach_transaction(async->root);

	if (IS_ERR(trans)) {

		if (PTR_ERR(trans) != -ENOENT)

			async->error = PTR_ERR(trans);

	/* if the commit is already started, we don't need to wait here */

	if (btrfs_transaction_blocked(async->root->fs_info))

		goto done;

	}



	/* Don't bother flushing if we got into a different transaction */

	if (trans->transid != async->transid) {

		btrfs_end_transaction(trans, async->root);

	trans = btrfs_join_transaction(async->root);

	if (IS_ERR(trans)) {

		async->error = PTR_ERR(trans);

		goto done;

	}
@@ -2869,10 +2866,15 @@ static void delayed_ref_async_start(struct btrfs_work *work) 
	 * wait on delayed refs

	 */

	trans->sync = true;



	/* Don't bother flushing if we got into a different transaction */

	if (trans->transid > async->transid)

		goto end;



	ret = btrfs_run_delayed_refs(trans, async->root, async->count);

	if (ret)

		async->error = ret;



end:

	ret = btrfs_end_transaction(trans, async->root);

	if (ret && !async->error)

		async->error = ret;