Re: [PATCH] btrfs: reset RO counter on block group if we fail to relocate

[Boris Burkov <boris@bur.io>]

On Mon, Jul 25, 2022 at 01:05:05PM -0400, Josef Bacik wrote:
> With the automatic block group reclaim code we will preemptively try to
> mark the block group RO before we start the relocation.  We do this to
> make sure we should actually try to relocate the block group.
> 
> However if we hit an error during the actual relocation we won't clean
> up our RO counter and the block group will remain RO.  This was observed
> internally with file systems reporting less space available from df when
> we had failed background relocations.
> 
> Fix this by doing the dec_ro in the error case.
> 
> Fixes: 18bb8bbf13c1 ("btrfs: zoned: automatically reclaim zones")
> Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Boris Burkov <boris@bur.io>
> ---
>  fs/btrfs/block-group.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
> index c3aecfb0a71d..993aca2f1e18 100644
> --- a/fs/btrfs/block-group.c
> +++ b/fs/btrfs/block-group.c
> @@ -1640,9 +1640,11 @@ void btrfs_reclaim_bgs_work(struct work_struct *work)
>  				div64_u64(zone_unusable * 100, bg->length));
>  		trace_btrfs_reclaim_block_group(bg);
>  		ret = btrfs_relocate_chunk(fs_info, bg->start);
> -		if (ret)
> +		if (ret) {
> +			btrfs_dec_block_group_ro(bg);
>  			btrfs_err(fs_info, "error relocating chunk %llu",
>  				  bg->start);
> +		}
>  
>  next:
>  		btrfs_put_block_group(bg);
> -- 
> 2.26.3
>