On Fri, Apr 17, 2020 at 4:38 PM <fdmanana@xxxxxxxxxx> wrote:
>
> From: Filipe Manana <fdmanana@xxxxxxxx>
>
> When cleaning pinned extents right before deleting an unused block group,
> we check if there's still a previous transaction running and if so we
> increment its reference count before using it for cleaning pinned ranges
> in its pinned extents iotree. However we ended up never decrementing the
> reference count after using the transaction, resulting in a memory leak.
>
> Fix it by decrementing the reference count.
>
> Signed-off-by: Filipe Manana <fdmanana@xxxxxxxx>
Fixes: fe119a6eeb6705 ("btrfs: switch to per-transaction pinned extents")
And missed that in v2, but had it in v1.
> ---
>
> V2: Use btrfs_put_transaction() and not refcount_dec(), otherwise we are
> not really releasing the memory used by the transaction in case its
> refcount is 1. Stupid mistake.
>
> fs/btrfs/block-group.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
> index 47f66c6a7d7f..af9e9a008724 100644
> --- a/fs/btrfs/block-group.c
> +++ b/fs/btrfs/block-group.c
> @@ -1288,11 +1288,15 @@ static bool clean_pinned_extents(struct btrfs_trans_handle *trans,
> if (ret)
> goto err;
> mutex_unlock(&fs_info->unused_bg_unpin_mutex);
> + if (prev_trans)
> + btrfs_put_transaction(prev_trans);
>
> return true;
>
> err:
> mutex_unlock(&fs_info->unused_bg_unpin_mutex);
> + if (prev_trans)
> + btrfs_put_transaction(prev_trans);
> btrfs_dec_block_group_ro(bg);
> return false;
> }
> --
> 2.11.0
>
