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Re: [PATCH 0/2] xfs: pass mp to XFS_WANT_CORRUPTED_*

To: Dave Chinner <david@xxxxxxxxxxxxx>
Subject: Re: [PATCH 0/2] xfs: pass mp to XFS_WANT_CORRUPTED_*
From: Brian Foster <bfoster@xxxxxxxxxx>
Date: Mon, 9 Feb 2015 16:43:59 -0500
Cc: Eric Sandeen <sandeen@xxxxxxxxxx>, xfs-oss <xfs@xxxxxxxxxxx>
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <20150209211744.GT12722@dastard>
References: <54D53E8C.8070207@xxxxxxxxxx> <20150208213502.GA4251@dastard> <20150209130926.GA18336@xxxxxxxxxxxxxx> <20150209211744.GT12722@dastard>
User-agent: Mutt/1.5.23 (2014-03-12)
On Tue, Feb 10, 2015 at 08:17:44AM +1100, Dave Chinner wrote:
> On Mon, Feb 09, 2015 at 08:09:26AM -0500, Brian Foster wrote:
> > On Mon, Feb 09, 2015 at 08:35:02AM +1100, Dave Chinner wrote:
> > > On Fri, Feb 06, 2015 at 04:22:04PM -0600, Eric Sandeen wrote:
> > > > These 2 patches provide information about which filesystem
> > > > hit the error...
> > > 
> > > If we are going to touch every one of these macros, then can we
> > > rename them to something a little shorter like XFS_CORRUPT_GOTO()
> > > and XFS_CORRUPT_RETURN() at the same time? That will make the code a
> > > little less eye-bleedy where there are lots of these statements,
> > > and make formatting of complex checks a bit easier, too...
> > > 
> > 
> > XFS_CORRUPT_DOSOMETHING() jumps out to me as indicate corruption if the
> > logic statement evaluates as true rather than false. The latter (e.g.,
> > assert-like logic) is how they work today, so that could be a bit
> > confusing to somebody who isn't already familiar with how these macros
> > work.
> 
> Someone not familiar with XFS conventions is already going to get
> caught by "should be true" logic of these statements anyway as the
> logic is the opposite of BUG_ON() and WARN_ON(). i.e.  BUG_ON(1)
> will kill the kernel, while ASSERT(1) indicates everything is fine.
> 

BUG_ON() and ASSERT() are self-explanatory, the latter being a pretty
standard/common thing ('man assert'). As Eric mentioned, the WANT bit of
the macro is what suggests assert-like semantics.

> I suggested shortening the macro because it makes the code that uses
> it extensively shouty and hard to read because it splits logic
> statements across lines regularly (e.g __xfs_dir3_data_check).  I
> want to use this more extensively in verifiers to give better
> corruption detection reporting, but the current macro will make the
> verifier code rather ugly. Hence my suggestion to make it shorter,
> neater and a little less shouty...
> 

Sure, but ASSERT_CORRUPT_RET() is the same length as the example above.
ASSERT_CORRUPT_GOTO() is only a few chars longer than the associated
example. We could still use WANT over ASSERT I suppose to shorten it up
further. Either of those are at least still self-explanatory in my
opinion.

Brian

> > Unfortunately, nothing shorter than the current naming immediately comes
> > to mind... :/ We could kill the XFS_ prefix I suppose or even invert the
> > logic of the calls, but that's certainly a more significant change.
> > Thoughts?
> 
> No logic changes, please.
> 
> Cheers,
> 
> Dave.
> -- 
> Dave Chinner
> david@xxxxxxxxxxxxx

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