Re: [PATCH] BUILD_BUG_ON sucks

From: Theodore Tso <tytso@mit.edu>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>,
	torvalds@linuxfoundation.org, rusty@rustcorp.com.au,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] BUILD_BUG_ON sucks
Date: Sun, 17 Aug 2008 08:19:06 -0400	[thread overview]
Message-ID: <20080817121906.GE8774@mit.edu> (raw)
In-Reply-To: <20080816104658.dcdfb0db.akpm@linux-foundation.org>

On Sat, Aug 16, 2008 at 10:46:58AM -0700, Andrew Morton wrote:
> >       what this code is supposed to do?
> > 
> > 	journal = handle->h_transaction->t_journal;
> > 	if (!journal_set_features(journal, 0, 0, JFS_FEATURE_INCOMPAT_REVOKE)) {
> > 		J_ASSERT (!"Cannot set revoke feature!");
> > 			 ^^^^
> 
> lol.  It's been there since I merged ext3 in 2.4.15.  Probably it was
> in sct's ext3 patches in the RH kernel.
> 
> Don't change it - it might be important!

Heh!  Well, it does the right thing, and doesn't take any extra text
space assuming a vaguely competent C compiler optimizer.  :-)

I'm pretty sure that back in the 2.4 days, we didn't have BUG_ON.  We
should do a s/J_ASSERT/BUG_ON/g pass over all of fs/jbd and fs/jbd2.
I'll submit patches for application when the 2.6.27 merge window opens
up --- or is this an obvious enough and safe enough transformation
that it will get accepted mainline at this point?

     	     	 	  	      	   - Ted