linux-kernel - Re: [PATCH v2] nvmet: fix mar and mor off-by-one errors

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Message-ID: <36b16998-3720-cc30-3ee8-b4d92c3b266d@nvidia.com>
Date:   Wed, 7 Sep 2022 02:43:47 +0000
From:   Chaitanya Kulkarni <chaitanyak@...dia.com>
To:     Damien Le Moal <damien.lemoal@...nsource.wdc.com>,
        Dennis Maisenbacher <Dennis.Maisenbacher@....com>,
        "linux-nvme@...ts.infradead.org" <linux-nvme@...ts.infradead.org>
CC:     Niklas Cassel <niklas.cassel@....com>,
        Christoph Hellwig <hch@....de>,
        Sagi Grimberg <sagi@...mberg.me>,
        Damien Le Moal <damien.lemoal@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] nvmet: fix mar and mor off-by-one errors


>>>    	if (le32_to_cpu(req->cmd->identify.nsid) == NVME_NSID_ALL) {
>>>    		req->error_loc = offsetof(struct nvme_identify, nsid);
>>> @@ -130,8 +131,20 @@ void nvmet_execute_identify_cns_cs_ns(struct nvmet_req *req)
>>>    	zsze = (bdev_zone_sectors(req->ns->bdev) << 9) >>
>>>    					req->ns->blksize_shift;
>>>    	id_zns->lbafe[0].zsze = cpu_to_le64(zsze);
>>> -	id_zns->mor = cpu_to_le32(bdev_max_open_zones(req->ns->bdev));
>>> -	id_zns->mar = cpu_to_le32(bdev_max_active_zones(req->ns->bdev));
>>> +
>>> +	mor = bdev_max_open_zones(req->ns->bdev);
>>> +	if (!mor)
>>> +		mor = U32_MAX;
>>> +	else
>>> +		--mor;
>>> +	id_zns->mor = cpu_to_le32(mor);
>>> +
>>> +	mar = bdev_max_active_zones(req->ns->bdev);
>>> +	if (!mar)
>>> +		mar = U32_MAX;
>>> +	else
>>> +		--mar;
>>> +	id_zns->mar = cpu_to_le32(mar);
>>>    
>>
>> above 14 lines of code can be simplified as in 4-5 lines :-
> 
> Simplified ? It is much harder to read in my opinion...
> 
>>

there are two if ... else ... doing identical things on same data
type u32 and its return type is also same le32,
if my suggestion is hard to read then common code needs
to be moved to the helper as it is not clear the need for
code duplication from commit message.

-ck