Re: [PATCH 1/1] scsi: sd: Rounddown host->opt_sectors to logical

[lukas@herbolt.com]

On 2025-11-20 17:07, John Garry wrote:
> On 20/11/2025 03:26, Martin K. Petersen wrote:
>> 
>> Lukas,
>> 
>>> The host->opt_sectors are by default 512 bytes aligned if we have 4KN
>>> SAS disk reporting zero or smaller opt_xfer_block than the
>>> host->opt_sectors we will end up with unaligned queue_limit->io_opt.
>> 
>> I am intrigued wrt. which controller returns a host->opt_sectors that
>> would trigger this misalignment. What is the actual value reported?
>> 
>>> +	lim.io_opt = rounddown(lim.logical_block_size,
>>> +			sdp->host->opt_sectors << SECTOR_SHIFT);
>> 
>> Those parameters would need to be reversed, I think. You want to round
>> down opt_sectors and not the logical_block_size.
>> 
> 
> In blk_validate_limits(), we already round down lim.io_opt to physical 
> block size, and physical block size >= logical block size (so this 
> extra rounding down should not be required). What am I missing?


Right, I overlooked it. The problematic kernel I was running is before 
this patch
9c0ba14828d64744ccd195c610594ba254a1a9ab which is setting the lim.io_opt 
to the proper value.

Thanks for the help!