From: Tom Yan <tom.ty89@gmail.com>
To: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Tejun Heo <tj@kernel.org>,
jmoyer@redhat.com, axboe@fb.com, linux-ide@vger.kernel.org,
linux-scsi@vger.kernel.org, linux-block@vger.kernel.org,
Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Subject: Re: [PATCH v2 2/2] libata-core: do not set dev->max_sectors for LBA48 devices
Date: Fri, 12 Aug 2016 13:18:28 +0800 [thread overview]
Message-ID: <CAGnHSEm0mGPG_y2a7hmCzQkwYE23Srozrm6eSPX8a3Q9a0y+7A@mail.gmail.com> (raw)
In-Reply-To: <yq1mvkipwx5.fsf@sermon.lab.mkp.net>
On 12 August 2016 at 10:01, Martin K. Petersen
<martin.petersen@oracle.com> wrote:
>
> Again, the point of max_hw_sectors and max_dev_sectors is to enforce the
> hard limits of controller and device respectively. Nothing else.
>
Sounds like libata-scsi is doing something wrong then. It should not
set max_hw_sectors to dev->max_sectors that is set by libata-core:
> blk_queue_max_hw_sectors(q, dev->max_sectors);
but instead it should report it as Maximum Transfer Length and let sd
set it as max_dev_sectors:
> put_unaligned_be32(dev->max_sectors, &rbuf[8]);
While max_hw_sectors will be left untouched (in the case of AHCI, for
example, since its SCSI host template does not have max_sectors set;
so max_hw_sectors will be SCSI_DEFAULT_MAX_SECTORS).
Although that means setting dev->max_sectors to a value larger than
1024 will probably be a no-op, if that's really an issue, we should
have the host templates in libata updated.
Make sense?
next prev parent reply other threads:[~2016-08-12 5:18 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-09 14:45 [PATCH v2 1/2] libata-scsi: set max_hw_sectors again only when dev->max_sectors is set tom.ty89
2016-08-09 14:45 ` [PATCH v2 2/2] libata-core: do not set dev->max_sectors for LBA48 devices tom.ty89
2016-08-09 16:50 ` Sergei Shtylyov
2016-08-10 4:10 ` Tejun Heo
2016-08-10 8:32 ` Tom Yan
2016-08-10 15:22 ` Tejun Heo
2016-08-11 3:37 ` Martin K. Petersen
2016-08-11 9:30 ` Tom Yan
2016-08-12 2:01 ` Martin K. Petersen
2016-08-12 5:18 ` Tom Yan [this message]
2016-08-12 8:17 ` Tom Yan
2016-08-12 21:06 ` Martin K. Petersen
2016-08-12 9:16 ` One Thousand Gnomes
2016-08-12 21:17 ` Martin K. Petersen
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