GNU bug report logs - #41143
[PATCH 1/2] Add 'lvm-device-mapping'

Previous Next

Full log

Message #43 received at 41143 <at> debbugs.gnu.org (full text, mbox):

From: Ludovic Courtès <ludo <at> gnu.org>
To: Mikhail Tsykalov <tsymsh <at> gmail.com>
Cc: 41143 <at> debbugs.gnu.org
Subject: Re: [bug#41143] [PATCH 1/2] mapped-devices: Allow target to be list
 of strings
Date: Fri, 25 Sep 2020 18:20:51 +0200

Hi,

Mikhail Tsykalov <tsymsh <at> gmail.com> skribis:

[...]

>>> While this looks like a good idea, doesn't this break code that
>>> implements mapped-device and assumes that target is a string. Suddenly
>>> passing a string to a mapped-device constructor results in a list
>>> passed to open/close. Also, what functions should do if they expect a
>>> string but get a list of them? Ignore everything but the first item?
>>> Implement mandatory check function? Doesn't this change push
>>> complexity out of mapped-device to implementations of it.
>> The intent of what I propose above is (1) to not break existing code,
>> and (2) to avoid duplicating checks and conversions at every call site.
>>
>> #1 is achieved by providing a deprecated ‘mapped-device-target’
>> (singular) procedure, for example.
>>
>> Does that make sense?
>
> I'm sorry if I didn't make myself clear, but it doesn't seem like
> open/close functions even use any mapped-device-* procedures, they
> just get passed source and target field directly. What I meant was
> this change will require changes to luks-device-mapping,
> raid-device-mapping and all other device mappings that users may have
> implemented in their local trees/config.

Ah yes, got it.

I tend to think it’s OK though, if we assume all the implementations are
in-tree, which would be consistent with the fact that the internals (how
to implement a mapped device type) are undocumented.

WDYT?

IOW, I think we must provide compatibility for users (people writing
their OS config, including perhaps service definitions) while leaving us
the ability to change internal interfaces.

Thanks,
Ludo’.

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.