translate INVARIANTS to DEBUG for code from OpenSolaris

[Andriy Gapon]

on 29/07/2013 21:25 Steven Hartland said the following:
> ----- Original Message ----- From: "Andriy Gapon" <avg at FreeBSD.org>
> 
>> [zfs-devel@, fs@, dtrace@ are Bcc-ed]
>>
>> In OpenSolaris and its descendants DEBUG is used in a fashion similar to our
>> INVARIANTS.  For example, ASSERT macros are enabled by it.
>> In our kernel code DEBUG has a different meaning and enables far too verbose or
>> far too obscure code and, as such, it is very rarely enabled.
>>
>> The idea of a change that I would like to propose is to translate INVARIANTS
>> kernel option into DEBUG for the files that originated from OpenSolaris (and
>> hopefully only for them).
>>
>> The change:
>>    opensolaris code: translate INVARIANTS to DEBUG and ZFS_DEBUG
>>
>>    do this by forcing inclusion of
>>    sys/cddl/compat/opensolaris/sys/debug_compat.h
>>    via -include option into all source files from OpenSolaris.
>>    Note that this -include option must always be after -include opt_global.h.
>>
>>    Additionally, remove forced definition of DEBUG for some modules and fix
>>    their build without DEBUG.
>>
>>    Also, meaning of DEBUG was overloaded to enable WITNESS support for some
>>    OpenSolaris (primarily ZFS) locks.  Now this overloading is removed and
>>    that use of DEBUG is replaced with a new option OPENSOLARIS_WITNESS.
>>
>> http://people.freebsd.org/~avg/osol-invariants-debug.diff
>>
>> I would like to ask for your feedback on the soundness of the whole idea.
>> Also on the name, location and style of inclusion for
>> sys/cddl/compat/opensolaris/sys/debug_compat.h.
>> And on any other details of the proposed change.
>>
>> Testing is also welcome, of course.
>>
>> Thank you very much.
> 
> I'm not sure you need #define ZFS_DEBUG as its already a dependency on
> DEBUG see:
> sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zfs_debug.h

Good point.  Thank you.

> Should this connection be broken and INVARIANTS only trigger DEBUG by
> default? One potential reason for this distinction is that ZFS_DEBUG brings
> with it some potentially quite heavy weight validation such as dnode_verify.
> 
> If so I have small list of additional fixes here that where required when
> I tested enabling ASSERTS checking without ZFS_DEBUG.
> 
> What do others think, should INVARIANTS trigger ZFS_DEBUG or should that
> be kept seperate?

I would prefer to follow what upstream does in this respect.
If DEBUG implies ZFS_DEBUG upstream, then I think that we should do the same for
INVARIANTS -> DEBUG -> ZFS_DEBUG.
Unless there are strong reasons to do otherwise.

-- 
Andriy Gapon