linux-ext4 - Re: [PATCH 1/2] ext4: fix race when setting the bitmap corrupted flag again

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Message-ID: <3e2b94e8-935e-b4bb-f40d-19aa3cce1d24@huawei.com>
Date:   Wed, 19 Dec 2018 11:35:12 +0800
From:   "zhangyi (F)" <yi.zhang@...wei.com>
To:     Wang Shilong <wshilong@....com>,
        "linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>
CC:     "tytso@....edu" <tytso@....edu>,
        "adilger.kernel@...ger.ca" <adilger.kernel@...ger.ca>,
        "miaoxie@...wei.com" <miaoxie@...wei.com>
Subject: Re: [PATCH 1/2] ext4: fix race when setting the bitmap corrupted flag
 again

On 2018/12/18 22:25, Wang Shilong Wrote:
> Hi,
> 
> 在 2018/12/18 下午7:57，“zhangyi (F)”<yi.zhang@...wei.com> 写入:
> 
>     Commit 9af0b3d12577 "ext4: fix race when setting the bitmap corrupted
>     flag" want to fix race between setting inode/block bitmap corrupted
>     flag and reducing free group inodes/clusters counter to prevent
>     multiple frees. But ext4_test_and_set_bit() will invoke
>     __test_and_set_bit() which is non-atomic, so the race is still there.
>     Fix this by invoke test_and_set_bit() instead.
>    
>     Fixes: 9af0b3d12577 ("ext4: fix race when setting the bitmap corrupted flag")
>     Signed-off-by: zhangyi (F) <yi.zhang@...wei.com>
> 
> Thanks for fixing this!, I was not aware of __test_and_set_bit() is not non-atomic operation before.
> 
> Reviewed-by: Wang Shilong <wshilong@....com>
> 
> Btw for a stable process question, commit 9af0b3d12577 had CC tag to Stable kernel, should we
> add it again here or with 'Fixes' tag, it will be included automatically?
> 
Thank you for reminding me of the CC stable tag, I missed this tag and I'm not sure it
will be added automatically or not. Anyway, I will add this tag in the next iteration.

Thanks,
Yi.