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Subject: Re: [RFC] inode.i_opflags - Usage of two different locking schemes
To:     Jan Kara <jack@suse.cz>
Cc:     "Theodore Ts'o" <tytso@mit.edu>,
        Horst Schirmeier <horst.schirmeier@tu-dortmund.de>,
        Jan Kara <jack@suse.com>, linux-ext4@vger.kernel.org,
        linux-kernel@vger.kernel.org
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 <0f387f5b-a516-af45-856d-f38d1adfadf5@tu-dortmund.de>
 <20210316171429.GA22701@quack2.suse.cz>
From:   Alexander Lochmann <alexander.lochmann@tu-dortmund.de>
Message-ID: <0e308673-a350-98af-b0a7-cde63abd4579@tu-dortmund.de>
Date:   Fri, 26 Mar 2021 17:37:34 +0100
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On 16.03.21 18:14, Jan Kara wrote:
> 
> So i_lock is supposed to protect i_opflags for writing AFAICT. For reading
> we don't seem to bother in some cases and I agree that is potentially
> problematic. It is *mostly* OK because we initialize i_opflags when loading
> inode into memory / adding it to dcache. But sometimes we also update them
> while the inode is alive. Now this is fine for the particular flag we
> update but in theory, if the compiler wants to screw us and stores
> temporarily some nonsensical value in i_opflags we'd have a problem. This
> is mostly a theoretical issue but eventually we probably want to fix this.
> 
> 								Honza
> 
Thx for the detailed explanation. :-)

- Alex

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