linux-kernel - Re: [PATCH] s390: Fix me in dasd

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Date:	Mon, 28 Jul 2014 18:02:13 +0200
From:	Stefan Weinhuber <WEIN@...ibm.com>
To:	Nicholas Krause <xerofoify@...il.com>
Cc:	BOEBLINGEN LINUX390 <LINUX390@...ibm.com>,
	heicars2@...ux.vnet.ibm.com, linux-kernel@...r.kernel.org,
	linux-s390@...r.kernel.org, mschwid2@...ux.vnet.ibm.com,
	Stefan Haberland1 <stefan.haberland@...ibm.com>
Subject: Re: [PATCH] s390: Fix me in dasd_eer.c

Nicholas Krause <xerofoify@...il.com> wrote on 2014-07-22 08:29:32:

[..] 
> Subject:
> 
> [PATCH] s390: Fix me in dasd_eer.c
> 
> This patch changes return type to EMEDUIMTYPE in function, 
dasd_eer_enable
> for when checking if the medium has no errors according to this 
function.
> 
> Signed-off-by: Nicholas Krause <xerofoify@...il.com>
> ---
>  drivers/s390/block/dasd_eer.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/s390/block/dasd_eer.c 
b/drivers/s390/block/dasd_eer.c
> index 21ef63c..08ee040 100644
> --- a/drivers/s390/block/dasd_eer.c
> +++ b/drivers/s390/block/dasd_eer.c
> @@ -462,7 +462,7 @@ int dasd_eer_enable(struct dasd_device *device)
>        return 0;
> 
>     if (!device->discipline || strcmp(device->discipline->name, "ECKD"))
> -      return -EPERM;   /* FIXME: -EMEDIUMTYPE ? */
> +      return -EMEDIUMTYPE;   /* FIXME: -EMEDIUMTYPE ? */
> 
>     cqr = dasd_kmalloc_request(DASD_ECKD_MAGIC, 1 /* SNSS */,
>                 SNSS_DATA_SIZE, device);
> -- 
> 1.9.1
>

Hm, after some consideration, I have to disagree with your suggestion.
If you try to enable EER on an FBA device, you will get the following
result with current code:

$ echo 1 > eer_enabled
-bash: echo: write error: Operation not permitted

and with your code the following:

$ echo 1 > eer_enabled
-bash: echo: write error: Wrong medium type

When I wrote this code, I was not sure which one is better. But today I 
say
that the 'Operation not permitted' is more to the point. An FBA device
has no (changable) medium, so what could be wrong about its type?
Could be confusing.

>From your patch description I do not really get why you want to change the
return code. Why do you think that EMEDIUMTYPE is better than EPERM?

Mit freundlichen Grüßen / Kind regards
 
Stefan Weinhuber

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