Re: [PATCH] btrfs: fix bytes_may_use leak in do_remap_reloc_trans()

[Boris Burkov <boris@bur.io>]

On Mon, Mar 23, 2026 at 02:36:51PM +0000, Mark Harmstone wrote:
> If the call to btrfs_reserve_extent() in do_remap_reloc_trans() returns
> a smaller extent than we asked for, currently we're not undoing the
> bytes_may_use change that we made. Fix this by calling
> btrfs_space_info_update_bytes_may_use() again for the difference.
> 
> Signed-off-by: Mark Harmstone <mark@harmstone.com>
Reviewed-by: Boris Burkov <boris@bur.io>
> Fixes: fd6594b1446c ("btrfs: replace identity remaps with actual remaps when doing relocations")
> ---
>  fs/btrfs/relocation.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
> index 1c42c5180bddd5..c0bd6db6011965 100644
> --- a/fs/btrfs/relocation.c
> +++ b/fs/btrfs/relocation.c
> @@ -5000,6 +5000,12 @@ static int do_remap_reloc_trans(struct btrfs_fs_info *fs_info,
>  		return ret;
>  	}
>  
> +	if (ins.offset < remap_length) {
> +		spin_lock(&sinfo->lock);
> +		btrfs_space_info_update_bytes_may_use(sinfo, ins.offset - remap_length);
> +		spin_unlock(&sinfo->lock);
> +	}
> +
>  	made_reservation = true;
>  
>  	new_addr = ins.objectid;
> -- 
> 2.52.0
>