Re: [PATCH 05/10] block: null: use blk_is_valid_logical_block_size

From: Damien Le Moal <Damien.LeMoal@wdc.com>
To: Maxim Levitsky <mlevitsk@redhat.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: Keith Busch <kbusch@kernel.org>,
	Josef Bacik <josef@toxicpanda.com>,
	"open list:BLOCK LAYER" <linux-block@vger.kernel.org>,
	Sagi Grimberg <sagi@grimberg.me>, Jens Axboe <axboe@kernel.dk>,
	"open list:NVM EXPRESS DRIVER" <linux-nvme@lists.infradead.org>,
	"open list:SCSI CDROM DRIVER" <linux-scsi@vger.kernel.org>,
	Tejun Heo <tj@kernel.org>, Bart Van Assche <bvanassche@acm.org>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	Jason Wang <jasowang@redhat.com>,
	Maxim Levitsky <maximlevitsky@gmail.com>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	Colin Ian King <colin.king@canonical.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Ulf Hansson <ulf.hansson@linaro.org>,
	Ajay Joshi <Ajay.Joshi@wdc.com>, Ming Lei <ming.lei@redhat.com>,
	"open list:SONY MEMORYSTICK SUBSYSTEM"
	<linux-mmc@vger.kernel.org>, Christoph Hellwig <hch@lst.de>,
	Satya Tangirala <satyat@google.com>,
	"open list:NETWORK BLOCK DEVICE (NBD)" <nbd@other.debian.org>,
	Hou Tao <houtao1@huawei.com>, Jens Axboe <axboe@fb.com>,
	"open list:VIRTIO CORE AND NET DRIVERS" 
	<virtualization@lists.linux-foundation.org>,
	"James E.J. Bottomley" <jejb@linux.ibm.com>,
	Alex Dubov <oakad@yahoo.com>
Subject: Re: [PATCH 05/10] block: null: use blk_is_valid_logical_block_size
Date: Tue, 21 Jul 2020 11:15:51 +0000	[thread overview]
Message-ID: <CY4PR04MB3751882A6BDF7C073D6ECF88E7780@CY4PR04MB3751.namprd04.prod.outlook.com> (raw)
In-Reply-To: 20200721105239.8270-6-mlevitsk@redhat.com

On 2020/07/21 19:54, Maxim Levitsky wrote:
> This slightly changes the behavier of the driver,

s/behavier/behavior

> when given invalid block size (non power of two, or below 512 bytes),
> but shoudn't matter.
> 
> Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
> ---
>  drivers/block/null_blk_main.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/block/null_blk_main.c b/drivers/block/null_blk_main.c
> index 87b31f9ca362e..e4df4b903b90b 100644
> --- a/drivers/block/null_blk_main.c
> +++ b/drivers/block/null_blk_main.c
> @@ -1684,8 +1684,8 @@ static int null_init_tag_set(struct nullb *nullb, struct blk_mq_tag_set *set)
>  
>  static int null_validate_conf(struct nullb_device *dev)
>  {
> -	dev->blocksize = round_down(dev->blocksize, 512);
> -	dev->blocksize = clamp_t(unsigned int, dev->blocksize, 512, 4096);
> +	if (!blk_is_valid_logical_block_size(dev->blocksize))
> +		return -ENODEV;
>  
>  	if (dev->queue_mode == NULL_Q_MQ && dev->use_per_node_hctx) {
>  		if (dev->submit_queues != nr_online_nodes)
> @@ -1865,7 +1865,7 @@ static int __init null_init(void)
>  	struct nullb *nullb;
>  	struct nullb_device *dev;
>  
> -	if (g_bs > PAGE_SIZE) {
> +	if (!blk_is_valid_logical_block_size(g_bs)) {
>  		pr_warn("invalid block size\n");
>  		pr_warn("defaults block size to %lu\n", PAGE_SIZE);
>  		g_bs = PAGE_SIZE;

Not sure if this change is OK. Shouldn't the if here be kept as is and
blk_is_valid_logical_block_size() called after it to check values lower than 4K ?

-- 
Damien Le Moal
Western Digital Research