Re: [PATCH 5/7] btrfs: zoned: subtract zone_unusable space in statfs

[Damien Le Moal <dlemoal@kernel.org>]

On 2026/05/13 21:34, Johannes Thumshirn wrote:
> On zoned filesystems, space in block groups that has been freed but not
> yet reset is tracked in bytes_zone_unusable. This space cannot be used for
> new allocations until zone reclaim resets the zones, but it was being
> reported as available space in statfs.
> 
> This caused statfs to over-report free space, leading to ENOSPC errors
> when applications tried to allocate based on the reported free space.
> 
> Fix this by subtracting bytes_zone_unusable from total_free_data in the
> statfs calculation for zoned filesystems.
> 
> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>

Fixes tag here as well ? and same for the following patch.

> ---
>  fs/btrfs/super.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
> index a0dbc0d2213f..498aa3039fbe 100644
> --- a/fs/btrfs/super.c
> +++ b/fs/btrfs/super.c
> @@ -1752,6 +1752,8 @@ static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
>  					factor = btrfs_bg_type_to_factor(
>  						btrfs_raid_array[i].bg_flag);
>  			}
> +
> +			total_free_data -= found->bytes_zone_unusable * factor;
>  		}
>  
>  		/*


-- 
Damien Le Moal
Western Digital Research