[PATCH 3/1] xfs: don't reset b_retries to 0 on every failure

[Carlos Maiolino]

On Fri, Jul 08, 2016 at 11:33:23PM -0500, Eric Sandeen wrote:
> With the code as it stands today, b_retries never increments
> because it gets reset to 0 in the error callback.
> 
> Remove that, and fix a similar problem where the first retry
> time was constantly being overwritten, which defeated the
> timeout tunable as well.
> 
> We now only set first retry time if a non-zero timeout is
> set, to match the behavior of only incrementing retries if
> a retry value is set.
> 
> This way max retries & timeouts consistently take effect after
> a tunable is set, rather than acting retroactively on a buffer
> which has failed at some point in the past and has accumulated
> state from those prior failures.
> 
> Thanks to dchinner for talking through this with me.
> 
> Signed-off-by: Eric Sandeen <sandeen at redhat.com>

This patch looks good, thanks Eric :)

Reviewed-by: Carlos Maiolino <cmaiolino at redhat.com>

> ---
> 
> diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c
> index 6a2f429..3b19e52 100644
> --- a/fs/xfs/xfs_buf_item.c
> +++ b/fs/xfs/xfs_buf_item.c
> @@ -1073,6 +1073,8 @@ xfs_buf_iodone_callback_error(
>  	trace_xfs_buf_item_iodone_async(bp, _RET_IP_);
>  	ASSERT(bp->b_iodone != NULL);
>  
> +	cfg = xfs_error_get_cfg(mp, XFS_ERR_METADATA, bp->b_error);
> +
>  	/*
>  	 * If the write was asynchronous then no one will be looking for the
>  	 * error.  If this is the first failure of this type, clear the error
> @@ -1084,8 +1086,8 @@ xfs_buf_iodone_callback_error(
>  	     bp->b_last_error != bp->b_error) {
>  		bp->b_flags |= (XBF_WRITE | XBF_DONE | XBF_WRITE_FAIL);
>  		bp->b_last_error = bp->b_error;
> -		bp->b_retries = 0;
> -		bp->b_first_retry_time = jiffies;
> +		if (cfg->retry_timeout && !bp->b_first_retry_time)
> +			bp->b_first_retry_time = jiffies;
>  
>  		xfs_buf_ioerror(bp, 0);
>  		xfs_buf_submit(bp);
> @@ -1096,7 +1098,6 @@ xfs_buf_iodone_callback_error(
>  	 * Repeated failure on an async write. Take action according to the
>  	 * error configuration we have been set up to use.
>  	 */
> -	cfg = xfs_error_get_cfg(mp, XFS_ERR_METADATA, bp->b_error);
>  
>  	if (cfg->max_retries != XFS_ERR_RETRY_FOREVER &&
>  	    ++bp->b_retries > cfg->max_retries)
> 
> 
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-- 
Carlos