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Date:   Tue, 29 Jan 2019 16:21:27 +0100
From:   David Sterba <dsterba@suse.cz>
To:     Anders Roxell <anders.roxell@linaro.org>
Cc:     clm@fb.com, josef@toxicpanda.com, dsterba@suse.com,
        linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] btrfs: relocation: fix unused variable
Message-ID: <20190129152127.GN2900@twin.jikos.cz>
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On Tue, Jan 29, 2019 at 02:01:46PM +0100, Anders Roxell wrote:
> When CONFIG_BRTFS_ASSERT isn't enabled, variable root_objectid isn't used.
> 
> fs/btrfs/relocation.c: In function ‘insert_dirty_subv’:
> fs/btrfs/relocation.c:2138:6: warning: unused variable ‘root_objectid’ [-Wunused-variable]
>   u64 root_objectid = root->root_key.objectid;
>       ^~~~~~~~~~~~~
> 
> Reworked by adding a runtime check in the assfail function instead of
> the '#ifdef CONFIG_BTRFS_ASSERT #else ...", so the compiler sees the
> condition being passed into an inline function after preprocessing.

I've fixed the warning by avoiding the local variable but I like your
fix in general, thanks.