Re: [PATCH 1/2] loop: Report EOPNOTSUPP properly

[Ming Lei]

On Tue, Oct 30, 2018 at 04:06:23PM -0700, Evan Green wrote:
> Properly plumb out EOPNOTSUPP from loop driver operations, which may
> get returned when for instance a discard operation is attempted but not
> supported by the underlying block device. Before this change, everything
> was reported in the log as an I/O error, which is scary and not
> helpful in debugging.
> 
> Signed-off-by: Evan Green <evgreen@xxxxxxxxxxxx>
> ---
> 
>  drivers/block/loop.c | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/block/loop.c b/drivers/block/loop.c
> index abad6d15f9563..28990fc94841a 100644
> --- a/drivers/block/loop.c
> +++ b/drivers/block/loop.c
> @@ -458,8 +458,13 @@ static void lo_complete_rq(struct request *rq)
>  
>  	if (!cmd->use_aio || cmd->ret < 0 || cmd->ret == blk_rq_bytes(rq) ||
>  	    req_op(rq) != REQ_OP_READ) {
> -		if (cmd->ret < 0)
> -			ret = BLK_STS_IOERR;
> +		if (cmd->ret < 0) {
> +			if (cmd->ret == -EOPNOTSUPP)
> +				ret = BLK_STS_NOTSUPP;
> +			else
> +				ret = BLK_STS_IOERR;
> +		}
> +
>  		goto end_io;
>  	}
>  
> @@ -1788,7 +1793,10 @@ static void loop_handle_cmd(struct loop_cmd *cmd)
>   failed:
>  	/* complete non-aio request */
>  	if (!cmd->use_aio || ret) {
> -		cmd->ret = ret ? -EIO : 0;
> +		if (ret == -EOPNOTSUPP)
> +			cmd->ret = ret;
> +		else
> +			cmd->ret = ret ? -EIO : 0;
>  		blk_mq_complete_request(rq);
>  	}
>  }
> -- 
> 2.16.4
> 

Looks fine:

Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx>

Thanks,
Ming