Re: [PATCH v7 1/2] loop: Report EOPNOTSUPP properly

[Gwendal Grignou]

 Reviewed-by: Gwendal Grignou <gwendal@xxxxxxxxxxxx>

On Thu, Nov 14, 2019 at 3:50 PM Evan Green <evgreen@xxxxxxxxxxxx> 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>
> ---
>
> Changes in v7:
> - Use errno_to_blk_status() (Christoph)
>
> Changes in v6:
> - Updated tags
>
> Changes in v5: None
> Changes in v4: None
> Changes in v3:
> - Updated tags
>
> Changes in v2:
> - Unnested error if statement (Bart)
>
>  drivers/block/loop.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/block/loop.c b/drivers/block/loop.c
> index ef6e251857c8..6a9fe1f9fe84 100644
> --- a/drivers/block/loop.c
> +++ b/drivers/block/loop.c
> @@ -461,7 +461,7 @@ 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;
> +                       ret = errno_to_blk_status(cmd->ret);
>                 goto end_io;
>         }
>
> @@ -1950,7 +1950,10 @@ 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);
>         }
>  }
> --
> 2.21.0
>