Re: [PATCH] btrfs: zoned: use filesystem size not disk size for reclaim decision

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

On 2025/05/20 9:20, Johannes Thumshirn wrote:
> From: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> 
> When deciding if a zoned filesystem is reaching the threshold to reclaim
> data block-groups, look at the size of the filesystem not to potentially
> total available size  of all drives in the filesystem.
> 
> Especially if a filesystem was create with mkfs' -b option, constraining
> it to only a portion of the block device, the numbers won't match and
> potentially garbage collection is kicking in too late.
> 
> Fixes: 3687fcb0752a ("btrfs: zoned: make auto-reclaim less aggressive")
> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>

Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Tested-by: Damien Le Moal <dlemoal@kernel.org>


> ---
>  fs/btrfs/zoned.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
> index b5b0156d5b95..19710634d63f 100644
> --- a/fs/btrfs/zoned.c
> +++ b/fs/btrfs/zoned.c
> @@ -2465,8 +2465,8 @@ bool btrfs_zoned_should_reclaim(const struct btrfs_fs_info *fs_info)
>  {
>  	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
>  	struct btrfs_device *device;
> +	u64 total = btrfs_super_total_bytes(fs_info->super_copy);
>  	u64 used = 0;
> -	u64 total = 0;
>  	u64 factor;
>  
>  	ASSERT(btrfs_is_zoned(fs_info));
> @@ -2479,7 +2479,6 @@ bool btrfs_zoned_should_reclaim(const struct btrfs_fs_info *fs_info)
>  		if (!device->bdev)
>  			continue;
>  
> -		total += device->disk_total_bytes;
>  		used += device->bytes_used;
>  	}
>  	mutex_unlock(&fs_devices->device_list_mutex);


-- 
Damien Le Moal
Western Digital Research