Re: [PATCH] btrfs: fix the length of reserved qgroup to free

[Qu Wenruo]

在 2024/10/8 17:18, iamhswang@xxxxxxxxx 写道:
> From: Haisu Wang <haisuwang@xxxxxxxxxxx>
>
> The dealloc flag may be cleared and the extent won't reach the disk
> in cow_file_range when errors path. The reserved qgroup space is
> freed in commit 30479f31d44d ("btrfs: fix qgroup reserve leaks in
> cow_file_range"). However, the length of untouched region to free
> need to be adjusted with the region size.
>
> Fixes: 30479f31d44d ("btrfs: fix qgroup reserve leaks in cow_file_range")
> Signed-off-by: Haisu Wang <haisuwang@xxxxxxxxxxx>

Right, just several lines before that, we increased @start by
@cur_alloc_size if @extent_reserved is true.

So we can not directly use the old range size.

You can improve that one step further by not modifying @start just for
the error handling path, although that should be another patch.

Reviewed-by: Qu Wenruo <wqu@xxxxxxxx>

Thanks,
Qu

> ---
>   fs/btrfs/inode.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index b0ad46b734c3..5eefa2318fa8 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -1592,7 +1592,7 @@ static noinline int cow_file_range(struct btrfs_inode *inode,
>   		clear_bits |= EXTENT_CLEAR_DATA_RESV;
>   		extent_clear_unlock_delalloc(inode, start, end, locked_folio,
>   					     &cached, clear_bits, page_ops);
> -		btrfs_qgroup_free_data(inode, NULL, start, cur_alloc_size, NULL);
> +		btrfs_qgroup_free_data(inode, NULL, start, end - start + 1, NULL);
>   	}
>   	return ret;
>   }