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Subject: Re: [PATCH] erofs: initialized fields can only be observed after bit
 is set
To:     Gao Xiang <hsiangkao@aol.com>, linux-erofs@lists.ozlabs.org
Cc:     LKML <linux-kernel@vger.kernel.org>, stable@vger.kernel.org
References: <20210209130618.15838-1-hsiangkao.ref@aol.com>
 <20210209130618.15838-1-hsiangkao@aol.com>
From:   Chao Yu <chao@kernel.org>
Message-ID: <801d8f5d-9d5f-bc6a-1796-70d1038611da@kernel.org>
Date:   Thu, 11 Feb 2021 11:45:20 +0800
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On 2021/2/9 21:06, Gao Xiang via Linux-erofs wrote:
> From: Gao Xiang <hsiangkao@redhat.com>
> 
> Currently, although set_bit() & test_bit() pairs are used as a fast-
> path for initialized configurations. However, these atomic ops are
> actually relaxed forms. Instead, load-acquire & store-release form is
> needed to make sure uninitialized fields won't be observed in advance
> here (yet no such corresponding bitops so use full barriers instead.)
> 
> Fixes: 62dc45979f3f ("staging: erofs: fix race of initializing xattrs of a inode at the same time")
> Fixes: 152a333a5895 ("staging: erofs: add compacted compression indexes support")
> Cc: <stable@vger.kernel.org> # 5.3+
> Reported-by: Huang Jianan <huangjianan@oppo.com>
> Signed-off-by: Gao Xiang <hsiangkao@redhat.com>

Thanks for detailed explanation for barrier offline.

Reviewed-by: Chao Yu <yuchao0@huawei.com>

Thanks,