On 09/14/2012 09:01 PM, Liu Bo wrote: > On 09/14/2012 08:41 PM, Josef Bacik wrote: >> On Fri, Sep 14, 2012 at 02:58:04AM -0600, Liu Bo wrote: >>> In some workloads we have nested joining transaction operations, >>> eg. >>> run_delalloc_nocow >>> btrfs_join_transaction >>> cow_file_range >>> btrfs_join_transaction >>> >>> it can be a serious bug since each trans handler has only two >>> block_rsv, orig_rsv and block_rsv, which means we may lose our >>> first block_rsv after two joining transaction operations: >>> >>> 1) btrfs_start_transaction >>> trans->block_rsv = A >>> >>> 2) btrfs_join_transaction >>> trans->orig_rsv = trans->block_rsv; ---> orig_rsv is now A >>> trans->block_rsv = B >>> >>> 3) btrfs_join_transaction >>> trans->orig_rsv = trans->block_rsv; ---> orig_rsv is now B >>> trans->block_rsv = C >>> ... >>> >> >> I'd like to see the actual stack trace where this happens, because I don't think >> it can happen. And if it is we need to look at that specific case and adjust it >> as necessary and not add a bunch of kmallocs just to track the block_rsv, >> because frankly it's not that big of a deal, it was just put into place in case >> somebody wasn't expecting a call they made to start another transaction and >> reset the block_rsv, which I don't actually think happens anywhere. So NAK on >> this patch, give me more information so I can figure out the right way to deal >> with this. Thanks, >> > > Fine, please run xfstests 068 till it hits a BUG_ON inside either btrfs_delete_delayed_dir_index or > btrfs_insert_delayed_dir_index. > > What I saw is that the orig_rsv and block_rsv is both delalloc_block_rsv, which is already lack of space. > and trans->use_count has been 3. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
