From: John Garry <john.g.garry@oracle.com>
To: "Martin K. Petersen" <martin.petersen@oracle.com>,
Lukas Herbolt <lukas@herbolt.com>
Cc: James.Bottomley@HansenPartnership.com, linux-scsi@vger.kernel.org
Subject: Re: [PATCH 1/1] scsi: sd: Rounddown host->opt_sectors to logical
Date: Thu, 20 Nov 2025 16:07:15 +0000 [thread overview]
Message-ID: <4728a1b9-7282-4cd3-8a36-5d8f19bd1cc0@oracle.com> (raw)
In-Reply-To: <yq1ecpt9yqb.fsf@ca-mkp.ca.oracle.com>
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?
next prev parent reply other threads:[~2025-11-20 16:07 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-14 10:28 [PATCH 0/1] Fix unaligned queue_limit->io_opt on SAS and 4KN disk Lukas Herbolt
2025-11-14 10:28 ` [PATCH 1/1] scsi: sd: Rounddown host->opt_sectors to logical Lukas Herbolt
2025-11-20 3:26 ` Martin K. Petersen
2025-11-20 12:07 ` lukas
2025-11-20 16:07 ` John Garry [this message]
2025-11-21 8:34 ` lukas
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