Re: [PATCH/RFC] sunrpc/cache: make cache flushing more reliable.

[Neil Brown <neilb@suse.com>]

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Sorry.. I didn't refresh before posting....

> @@ -487,10 +496,13 @@ EXPORT_SYMBOL_GPL(cache_flush);
>  
>  void cache_purge(struct cache_detail *detail)
>  {
> -	detail->flush_time = LONG_MAX;
> +	time_t now = seconds_since_boot();
> +	if (detail->flush_time >= now)
> +		now = detail->flush_time + 1;
> +	/* 'now' is the maximum value any 'last_refresh' can have */
> +	detail->flush_time = now + 1;

This should not have the '+ 1'.

>  	detail->nextcheck = seconds_since_boot();
>  	cache_flush();
> -	detail->flush_time = 1;
>  }
>  EXPORT_SYMBOL_GPL(cache_purge);
>  
> @@ -1447,8 +1460,22 @@ static ssize_t write_flush(struct file *file, const char __user *buf,
>  		return -EINVAL;
>  
>  	bp = tbuf;
> -	cd->flush_time = get_expiry(&bp);
> -	cd->nextcheck = seconds_since_boot();
> +	then = get_expiry(&bp);
> +	now = seconds_since_boot();
> +	cd->nextcheck = now;
> +	/* Can only set flush_time to 1 second beyond "now", or
> +	 * possibly 1 second beyond flushtime.  This is because
> +	 * flush_time never goes backwards so it mustn't get too far
> +	 * ahead of time.
> +	 */
> +	if (then >= now) {
> +		/* Want to flush everything, so behave like cache_purge() */
> +		if (cd->flush_time >= now)
> +			now = cd->flush_time + 1;
> +		then = now + 1;

Nor should.

I'll resend it people are otherwise happy.

NeilBrown

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