linux-kernel - Re: [PATCH 1/1] device-dax: delete a redundancy check in dev_dax_validate

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Message-ID: <7ccddd02-e2e6-ec48-43b8-10700285e61c@huawei.com>
Date:   Fri, 20 Nov 2020 17:27:25 +0800
From:   "Leizhen (ThunderTown)" <thunder.leizhen@...wei.com>
To:     Dan Williams <dan.j.williams@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        linux-nvdimm <linux-nvdimm@...ts.01.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/1] device-dax: delete a redundancy check in
 dev_dax_validate_align()



On 2020/11/20 17:20, Zhen Lei wrote:
> After we have done the alignment check for the length of each range, the
> alignment check for dev_dax_size(dev_dax) is no longer needed, because it
> get the sum of the length of each range.

For example:
x/M + y/M = (x + y)/M
If x/M is a integer and y/M is also a integer, then (x + y)/M must be a integer.

> 
> Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
> ---
>  drivers/dax/bus.c | 7 -------
>  1 file changed, 7 deletions(-)
> 
> diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
> index 1efae11d947a..35f9238c0139 100644
> --- a/drivers/dax/bus.c
> +++ b/drivers/dax/bus.c
> @@ -1109,16 +1109,9 @@ static ssize_t align_show(struct device *dev,
>  
>  static ssize_t dev_dax_validate_align(struct dev_dax *dev_dax)
>  {
> -	resource_size_t dev_size = dev_dax_size(dev_dax);
>  	struct device *dev = &dev_dax->dev;
>  	int i;
>  
> -	if (dev_size > 0 && !alloc_is_aligned(dev_dax, dev_size)) {
> -		dev_dbg(dev, "%s: align %u invalid for size %pa\n",
> -			__func__, dev_dax->align, &dev_size);
> -		return -EINVAL;
> -	}
> -
>  	for (i = 0; i < dev_dax->nr_range; i++) {
>  		size_t len = range_len(&dev_dax->ranges[i].range);
>  
>