Re: [PATCH v2 2/3] btrfs: increase ->free_chunk_space in btrfs_grow_device

[David Sterba <dsterba@suse.cz>]

On Wed, Sep 27, 2023 at 01:47:00PM -0400, Josef Bacik wrote:
> My overcommit patch exposed a bug with btrfs/177.  The problem here is

Which patch is that?

> that when we grow the device we're not adding to ->free_chunk_space, so
> subsequent allocations can cause ->free_chunk_space to wrap, which
> causes problems in can_overcommit because we add this to ->total_bytes,
> which causes the counter to wrap and gives us an unexpected ENOSPC.
> 
> Fix this by properly updating ->free_chunk_space with the new available
> space in btrfs_grow_device.
> 
> Signed-off-by: Josef Bacik <josef@toxicpanda.com>
> ---
>  fs/btrfs/volumes.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 907ea775f4e4..1aedd15d1db7 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -2932,6 +2932,7 @@ int btrfs_grow_device(struct btrfs_trans_handle *trans,
>  	btrfs_set_super_total_bytes(super_copy,
>  			round_down(old_total + diff, fs_info->sectorsize));
>  	device->fs_devices->total_rw_bytes += diff;
> +	atomic64_add(diff, &fs_info->free_chunk_space);
>  
>  	btrfs_device_set_total_bytes(device, new_size);
>  	btrfs_device_set_disk_total_bytes(device, new_size);
> -- 
> 2.41.0