Commit 25983713 authored by Filipe Manana's avatar Filipe Manana Committed by David Sterba
Browse files

btrfs: don't BUG_ON() when unpinning extents during transaction commit 



In the final phase of a transaction commit, when unpinning extents at
btrfs_finish_extent_commit(), there's no need to BUG_ON() if we fail to
unpin an extent range. All that can happen is that we fail to return the
extent range to the in-memory free space cache, meaning no future space
allocations can reuse that extent range while the fs is mounted.

So instead return the error to the caller and make it abort the
transaction, so that the error is noticed and prevent misteriously leaking
space. We keep track of the first error we get while unpinning an extent
range and keep trying to unpin all the following extent ranges, so that
we attempt to do all discards. The transaction abort will deal with all
resource cleanups.

Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent b2460c2a

fs/btrfs/extent-tree.c

+18 −2
Original line number Diff line number Diff line
@@ -2821,6 +2821,7 @@ int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans) 
	struct extent_io_tree *unpin;

	u64 start;

	u64 end;

	int unpin_error = 0;

	int ret;



	unpin = &trans->transaction->pinned_extents;
@@ -2841,7 +2842,22 @@ int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans) 


		btrfs_clear_extent_dirty(unpin, start, end, &cached_state);

		ret = unpin_extent_range(fs_info, start, end, true);

		BUG_ON(ret);

		/*

		 * If we get an error unpinning an extent range, store the first

		 * error to return later after trying to unpin all ranges and do

		 * the sync discards. Our caller will abort the transaction

		 * (which already wrote new superblocks) and on the next mount

		 * the space will be available as it was pinned by in-memory

		 * only structures in this phase.

		 */

		if (ret) {

			btrfs_err_rl(fs_info,

"failed to unpin extent range [%llu, %llu] when committing transaction %llu: %s (%d)",

				     start, end, trans->transid,

				     btrfs_decode_error(ret), ret);

			if (!unpin_error)

				unpin_error = ret;

		}

		mutex_unlock(&fs_info->unused_bg_unpin_mutex);

		btrfs_free_extent_state(cached_state);

		cond_resched();
@@ -2888,7 +2904,7 @@ int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans) 
		}

	}



	return 0;

	return unpin_error;

}



/*

fs/btrfs/transaction.c

+3 −1
Original line number Diff line number Diff line
@@ -2554,7 +2554,9 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans) 
	wake_up(&cur_trans->commit_wait);

	btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_SUPER_COMMITTED);



	btrfs_finish_extent_commit(trans);

	ret = btrfs_finish_extent_commit(trans);

	if (ret)

		goto scrub_continue;



	if (test_bit(BTRFS_TRANS_HAVE_FREE_BGS, &cur_trans->flags))

		btrfs_clear_space_info_full(fs_info);