Re: [PATCH 7/8] block: refactor the bounce buffering code

From: Matthew Wilcox <willy@infradead.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>, Khalid Aziz <khalid@gonehiking.org>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	Hannes Reinecke <hare@suse.com>,
	Ondrej Zary <linux@rainbow-software.org>,
	linux-block@vger.kernel.org, linux-scsi@vger.kernel.org
Subject: Re: [PATCH 7/8] block: refactor the bounce buffering code
Date: Thu, 18 Mar 2021 11:29:50 +0000	[thread overview]
Message-ID: <20210318112950.GL3420@casper.infradead.org> (raw)
In-Reply-To: <20210318063923.302738-8-hch@lst.de>

On Thu, Mar 18, 2021 at 07:39:22AM +0100, Christoph Hellwig wrote:
> @@ -536,7 +518,7 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
>  					b->max_write_zeroes_sectors);
>  	t->max_zone_append_sectors = min(t->max_zone_append_sectors,
>  					b->max_zone_append_sectors);
> -	t->bounce_pfn = min_not_zero(t->bounce_pfn, b->bounce_pfn);
> +	t->bounce = min_not_zero(t->bounce, b->bounce);

I see how min_not_zero() made sense when it was a pfn.  Does it still
make sense now it's an enum?  I would have thought it'd now be 'max()',
given the definitions later on.

> +/*
> + * BLK_BOUNCE_NONE:	never bounce (default)
> + * BLK_BOUNCE_HIGH:	bounce all highmem pages
> + */
> +enum blk_bounce {
> +	BLK_BOUNCE_NONE,
> +	BLK_BOUNCE_HIGH,
> +};
> +
>  struct queue_limits {
> -	unsigned long		bounce_pfn;
> +	enum blk_bounce		bounce;
>  	unsigned long		seg_boundary_mask;
>  	unsigned long		virt_boundary_mask;
>  