Re: [PATCH v3 1/2] scsi: sd: Prevent logical_to_bytes() from returning overflowed values

[Damien Le Moal <dlemoal@kernel.org>]

On 6/13/25 00:53, Bart Van Assche wrote:
> On 6/11/25 11:02 PM, Damien Le Moal wrote:
>> Make sure that logical_to_bytes() does not return an overflowed value
>> by changing its return type from unsigned int (32-bits) to size_t
>> (64-bits).
> 
> size_t is only 64 bits on 64-bit systems. Shouldn't size_t be changed
> into u64? See also https://en.wikipedia.org/wiki/64-bit_computing.
> 
>> -static inline unsigned int logical_to_bytes(struct scsi_device *sdev, sector_t blocks)
>> +static inline size_t logical_to_bytes(struct scsi_device *sdev, sector_t blocks)
>>   {
>>   	return blocks * sdev->sector_size;
>>   }
> 
> Since 'blocks' represents an LBA instead of a byte offset divided by
> 512, please consider changing "sector_t blocks" into
> "u64 logical_blocks". Independent of this patch, "sector_size" probably
> should be renamed into "logical_block_size" since the word "sector" is
> only used in references to "physical sector" in the SBC specification.

Well, one could argue that struct scsi_device is SPC territory, not SBC, and
that "sector_size" or block size has no business being in struct scsi_device.
But changing that would not make access to that value easy when all we have is a
scsi command :)

> 
> Otherwise this patch looks good to me.
> 
> Thanks,
> 
> Bart.


-- 
Damien Le Moal
Western Digital Research