linux-kernel - Re: [PATCH] ext4: fix clang build regression

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Message-Id: <48473218.z3lFQE8RDq@localhost.localdomain>
Date:   Sat, 12 Aug 2017 14:09:29 +0530
From:   Chandan Rajendra <chandan@...ux.vnet.ibm.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     "Theodore Ts'o" <tytso@....edu>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        Stefan Agner <stefan@...er.ch>, Jan Kara <jack@...e.cz>,
        Daeho Jeong <daeho.jeong@...sung.com>,
        "Darrick J. Wong" <darrick.wong@...cle.com>,
        Konstantin Khlebnikov <khlebnikov@...dex-team.ru>,
        linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ext4: fix clang build regression

On Monday, August 7, 2017 4:26:51 PM IST Arnd Bergmann wrote:
> As Stefan pointed out, I misremembered what clang can do specifically,
> and it turns out that the variable-length array at the end of the
> structure did not work (a flexible array would have worked here
> but not solved the problem):
> 
> fs/ext4/mballoc.c:2303:17: error: fields must have a constant size:
> 'variable length array in structure' extension will never be supported
>                 ext4_grpblk_t counters[blocksize_bits + 2];
> 
> This reverts part of my previous patch, using a fixed-size array
> again, but keeping the check for the array overflow.
> 
> Fixes: 2df2c3402fc8 ("ext4: fix warning about stack corruption")
> Reported-by: Stefan Agner <stefan@...er.ch>
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

I executed xfstests on a ppc64 machine with both 4k and 64k block size 
combination.

Tested-by: Chandan Rajendra <chandan@...ux.vnet.ibm.com>

-- 
chandan