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Qu Wenruo authored
Commit 62b99540 (btrfs: relocation: Fix leaking qgroups numbers on data extents) only fixes the problem partly. The previous fix is to trace all new data extents at transaction commit time when balance finishes. However balance is not done in a large transaction, every path replacement can happen in its own transaction. This makes the fix useless if transaction commits during relocation. For example: relocate_block_group() |-merge_reloc_roots() | |- merge_reloc_root() | |- btrfs_start_transaction() <- Trans X | |- replace_path() <- Cause leak | |- btrfs_end_transaction_throttle() <- Trans X commits here | | Leak not fixed | | | |- btrfs_start_transaction() <- Trans Y | |- replace_path() <- Cause leak | |- btrfs_end_transaction_throttle() <- Trans Y ends | but not committed |-btrfs_join_transaction() <- Still trans Y |-qgroup_fix() <- Only fixes data leak | in trans Y |-btrfs_commit_transaction() <- Trans Y commits In that case, qgroup fixup can only fix data leak in trans Y, data leak in trans X is out of fix. So the correct fix should happen in the same transaction of replace_path(). This patch fixes it by tracing both subtrees of tree block swap, so it can fix the problem and ensure all leaking and fix are in the same transaction, so no leak again. Reported-by:
Goldwyn Rodrigues <rgoldwyn@suse.com> Signed-off-by:
Qu Wenruo <quwenruo@cn.fujitsu.com> Reviewed-and-Tested-by:
Goldwyn Rodrigues <rgoldwyn@suse.com> Signed-off-by:
David Sterba <dsterba@suse.com>
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