linux-kernel - Re: [PATCH V2] xfs: libxfs: move xfs_perag

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Message-ID: <20181127091602.eaeczahefobpx544@hades.usersys.redhat.com>
Date:   Tue, 27 Nov 2018 10:16:02 +0100
From:   Carlos Maiolino <cmaiolino@...hat.com>
To:     Pan Bian <bianpan2016@....com>
Cc:     "Darrick J. Wong" <darrick.wong@...cle.com>,
        Brian Foster <bfoster@...hat.com>,
        Dave Chinner <dchinner@...hat.com>, linux-xfs@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2] xfs: libxfs: move xfs_perag_put late

On Tue, Nov 27, 2018 at 08:33:38AM +0800, Pan Bian wrote:
> The function xfs_alloc_get_freelist calls xfs_perag_put to drop the
> reference. However, pag->pagf_btreeblks is read and write after the 
> put operation. This patch moves the put operation late.

I'm not a native English speaker too, but I believe it should be "is read and
written after..."

But, for the code itself, you can add:

Reviewed-by: Carlos Maiolino <cmaiolino@...hat.com>

Cheers

> 
> Signed-off-by: Pan Bian <bianpan2016@....com>
> ---
> V2: correct the commit log
> ---
>  fs/xfs/libxfs/xfs_alloc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
> index e1c0c0d..4be387d 100644
> --- a/fs/xfs/libxfs/xfs_alloc.c
> +++ b/fs/xfs/libxfs/xfs_alloc.c
> @@ -2435,7 +2435,6 @@ xfs_alloc_get_freelist(
>  	be32_add_cpu(&agf->agf_flcount, -1);
>  	xfs_trans_agflist_delta(tp, -1);
>  	pag->pagf_flcount--;
> -	xfs_perag_put(pag);
>  
>  	logflags = XFS_AGF_FLFIRST | XFS_AGF_FLCOUNT;
>  	if (btreeblk) {
> @@ -2443,6 +2442,7 @@ xfs_alloc_get_freelist(
>  		pag->pagf_btreeblks++;
>  		logflags |= XFS_AGF_BTREEBLKS;
>  	}
> +	xfs_perag_put(pag);
>  
>  	xfs_alloc_log_agf(tp, agbp, logflags);
>  	*bnop = bno;
> -- 
> 2.7.4
> 
> 

-- 
Carlos