linux-kernel - Re: [PATCH] fs/block_dev.c: always return error in thaw

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Message-ID: <20161003041346.4lvxz4ue3qfhyfpm@mguzik>
Date:   Mon, 3 Oct 2016 06:13:47 +0200
From:   Mateusz Guzik <mguzik@...hat.com>
To:     Pierre Morel <pmorel@...ux.vnet.ibm.com>
Cc:     linux-kernel@...r.kernel.org, viro@...iv.linux.org.uk,
        linux-fsdevel@...r.kernel.org, farman@...ux.vnet.ibm.com,
        cornelia.huck@...ibm.com
Subject: Re: [PATCH] fs/block_dev.c: always return error in thaw_bdev()

On Thu, Aug 20, 2015 at 12:07:49PM +0200, Pierre Morel wrote:
> When triggering thaw-filesystems via magic sysrq, the system enters a
> loop in do_thaw_one(), as thaw_bdev() still returns success if
> bd_fsfreeze_count == 0. To fix this, let thaw_bdev() always return
> error (and simplify the code a bit at the same time).
> 
> Reviewed-by: Eric Farman <farman@...ux.vnet.ibm.com>
> Reviewed-by: Cornelia Huck <cornelia.huck@...ibm.com>
> Signed-off-by: Pierre Morel <pmorel@...ux.vnet.ibm.com>
> ---
>  fs/block_dev.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index c7e4163..7809c92 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -269,14 +269,11 @@ int thaw_bdev(struct block_device *bdev, struct super_block *sb)
>  		error = sb->s_op->thaw_super(sb);
>  	else
>  		error = thaw_super(sb);
> -	if (error) {
> +	if (error)
>  		bdev->bd_fsfreeze_count++;
> -		mutex_unlock(&bdev->bd_fsfreeze_mutex);
> -		return error;
> -	}
>  out:
>  	mutex_unlock(&bdev->bd_fsfreeze_mutex);
> -	return 0;
> +	return error;
>  }
>  EXPORT_SYMBOL(thaw_bdev);
>  

Apparently this never got in.

The bug is still there, reproducible with mere:
echo j > /proc/sysrq-trigger

-- 
Mateusz Guzik