linux-kernel - Re: [PATCH 05/10] block: null: use blk_is_valid_logical_block

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Date:   Tue, 21 Jul 2020 11:15:51 +0000
From:   Damien Le Moal <Damien.LeMoal@....com>
To:     Maxim Levitsky <mlevitsk@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Keith Busch <kbusch@...nel.org>,
        Josef Bacik <josef@...icpanda.com>,
        "open list:BLOCK LAYER" <linux-block@...r.kernel.org>,
        Sagi Grimberg <sagi@...mberg.me>, Jens Axboe <axboe@...nel.dk>,
        "open list:NVM EXPRESS DRIVER" <linux-nvme@...ts.infradead.org>,
        "open list:SCSI CDROM DRIVER" <linux-scsi@...r.kernel.org>,
        Tejun Heo <tj@...nel.org>,
        Bart Van Assche <bvanassche@....org>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Jason Wang <jasowang@...hat.com>,
        Maxim Levitsky <maximlevitsky@...il.com>,
        Stefan Hajnoczi <stefanha@...hat.com>,
        Colin Ian King <colin.king@...onical.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Ajay Joshi <Ajay.Joshi@....com>,
        Ming Lei <ming.lei@...hat.com>,
        "open list:SONY MEMORYSTICK SUBSYSTEM" <linux-mmc@...r.kernel.org>,
        Christoph Hellwig <hch@....de>,
        Satya Tangirala <satyat@...gle.com>,
        "open list:NETWORK BLOCK DEVICE (NBD)" <nbd@...er.debian.org>,
        Hou Tao <houtao1@...wei.com>, Jens Axboe <axboe@...com>,
        "open list:VIRTIO CORE AND NET DRIVERS" 
        <virtualization@...ts.linux-foundation.org>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        Alex Dubov <oakad@...oo.com>
Subject: Re: [PATCH 05/10] block: null: use blk_is_valid_logical_block_size

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@...hat.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