Re: [PATCH] btrfs: fix reversed warning condition in btrfs_delayed_inode_reserve_metadata

[Liu Bo <bo.li.liu@oracle.com>]

On Wed, Apr 02, 2014 at 07:13:00PM +0200, David Sterba wrote:
> Commit fae7f21cece9a4c181 ("btrfs: Use WARN_ON()'s return value in place of
> WARN_ON(1)") cleaned up WARN_ON usage and in one place reversed the condition
> that led to loads of warnings that were not supposed to occur.
> 
> WARN_ON will trigger because it sees 'ret' though in the previous code
> did not reach the WARN_ON below. The correct pattern is
> 
> -       if (condition)
> +       if (WARN_ON(condition))
> 
> CC: Dulshani Gunawardhana <dulshani.gunawardhana89@gmail.com>
> CC: <stable@vger.kernel.org> # 3.13
> Reported-by: Liu Bo <bo.li.liu@oracle.com>
> Signed-off-by: David Sterba <dsterba@suse.cz>
> ---
>  fs/btrfs/delayed-inode.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
> index 451b00c86f6c..098af20abd88 100644
> --- a/fs/btrfs/delayed-inode.c
> +++ b/fs/btrfs/delayed-inode.c
> @@ -649,7 +649,7 @@ static int btrfs_delayed_inode_reserve_metadata(
>  			goto out;
>  
>  		ret = btrfs_block_rsv_migrate(src_rsv, dst_rsv, num_bytes);
> -		if (!WARN_ON(ret))
> +		if (WARN_ON(!ret))
>  			goto out;

Oh sorry, I'd have to get my Reviewed-by back and give a NACK instead.

With this patch, (ret = 0) triggers the WARNING, which is not right.

-liubo