linux-kernel - Re: [PATCH v1 6/7] xfs: Rewrite retried read

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Message-ID: <20181128051719.GK6311@dastard>
Date:   Wed, 28 Nov 2018 16:17:19 +1100
From:   Dave Chinner <david@...morbit.com>
To:     Allison Henderson <allison.henderson@...cle.com>
Cc:     linux-block@...r.kernel.org, linux-xfs@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        martin.petersen@...cle.com, shirley.ma@...cle.com,
        bob.liu@...cle.com
Subject: Re: [PATCH v1 6/7] xfs: Rewrite retried read

On Tue, Nov 27, 2018 at 08:49:50PM -0700, Allison Henderson wrote:
> If we had to try more than one mirror to get a successful
> read, then write that buffer back to correct the bad mirro
> 
> Signed-off-by: Allison Henderson <allison.henderson@...cle.com>
> ---
>  fs/xfs/xfs_buf.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
> index f102d01..81f6491 100644
> --- a/fs/xfs/xfs_buf.c
> +++ b/fs/xfs/xfs_buf.c
> @@ -847,6 +847,14 @@ xfs_buf_read_map(
>  
>  		}
>  retry_done:
> +
> +		/*
> +		 * if we had to try more than one mirror to sucessfully read
> +		 * the buffer, write the buffer back
> +		 */
> +		if (!bp->b_error && i > 0)
> +			xfs_bwrite(bp);
> +

This can go in the case statement on retry and then you don't need
to check for i > 0 or, well, bp->b_error. i.e.

		swtich (bp->b_error) {
		case -EBADCRC:
		case -EIO:
		case -EFSCORRUPTED:
			/* try again from different copy */
			continue;
		0:
			/* good copy, rewrite it to repair bad copy */
			xfs_bwrite(bp);
			/* fallthrough */
		default:
			return bp;
		}

Cheers,

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