linux-kernel - Re: [PATCH V2 2/2] fs/super.c: don't fool lockdep in freeze_super() and thaw

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Date:   Fri, 7 Oct 2016 08:59:20 +1100
From:   Dave Chinner <david@...morbit.com>
To:     Oleg Nesterov <oleg@...hat.com>
Cc:     Jan Kara <jack@...e.cz>, Al Viro <viro@...iv.linux.org.uk>,
        Nikolay Borisov <kernel@...p.com>,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        fstests@...r.kernel.org
Subject: Re: [PATCH V2 2/2] fs/super.c: don't fool lockdep in freeze_super()
 and thaw_super() paths

On Thu, Oct 06, 2016 at 07:17:58PM +0200, Oleg Nesterov wrote:
> Probably false positive? Although when I look at the comment above xfs_sync_sb()
> I think that may be sometging like below makes sense, but I know absolutely nothing
> about fs/ and XFS in particular.
> 
> Oleg.
> 
> 
> --- x/fs/xfs/xfs_trans.c
> +++ x/fs/xfs/xfs_trans.c
> @@ -245,7 +245,8 @@ xfs_trans_alloc(
>  	atomic_inc(&mp->m_active_trans);
>  
>  	tp = kmem_zone_zalloc(xfs_trans_zone,
> -		(flags & XFS_TRANS_NOFS) ? KM_NOFS : KM_SLEEP);
> +		(flags & (XFS_TRANS_NOFS | XFS_TRANS_NO_WRITECOUNT))
> +			? KM_NOFS : KM_SLEEP);
>  	tp->t_magic = XFS_TRANS_HEADER_MAGIC;
>  	tp->t_flags = flags;
>  	tp->t_mountp = mp;

Brief examination says caller should set XFS_TRANS_NOFS, not change
the implementation to make XFS_TRANS_NO_WRITECOUNT flag to also mean
XFS_TRANS_NOFS.

Cheers,

Dave.
-- 
Dave Chinner
david@...morbit.com