translate INVARIANTS to DEBUG for code from OpenSolaris

[Steven Hartland]

----- 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

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?

    Regards
    Steve

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