From: "Martin K. Petersen" <martin.petersen@oracle.com>
To: Matthew Wilcox <matthew@wil.cx>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>,
rwheeler@redhat.com, snitzer@redhat.com, jeff@garzik.org,
neilb@suse.de, James.Bottomley@hansenpartnership.com,
dgilbert@interlog.com, jens.axboe@oracle.com,
linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org
Subject: Re: [PATCH 8 of 8] libata: Report disk alignment and physical block size
Date: Thu, 23 Apr 2009 10:05:50 -0400 [thread overview]
Message-ID: <yq1iqkvbh35.fsf@sermon.lab.mkp.net> (raw)
In-Reply-To: <20090423134617.GO1926@parisc-linux.org> (Matthew Wilcox's message of "Thu, 23 Apr 2009 07:46:17 -0600")
>>>>> "Matthew" == Matthew Wilcox <matthew@wil.cx> writes:
Matthew> I found it clearer to do:
Matthew> u16 first = word_209 & 0x3fff; if
Matthew> (first)
Matthew> lowest_aligned = (1 <<
Matthew> log_per_phys) - first;
Matthew> but you may disagree.
I don't care much either way.
>> + rbuf[14] = (lowest_aligned_lba >> 8) & 0x3f;
Matthew> Hm, yes, it could overflow ... 1 << 0xf -1 is 32767 (0x7fff)
Matthew> which would be larger than could fit in SCSI's RC16 and ends up
Matthew> inadvertently setting Thin Provisioning Read Zeroes, which we
Matthew> really don't want. I suppose reporting 0x3fff is better than
Matthew> reporting anything else in this field. All highly theoretical,
Matthew> since you'd have to have 16MB physical sectors with 512 byte
Matthew> logical sectors to get to this situation.
Yeah, I agree it's mostly in the academic interest bucket. Just trying
to be defensive about what we return, that's all.
--
Martin K. Petersen Oracle Linux Engineering
next prev parent reply other threads:[~2009-04-23 14:07 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-23 5:29 [PATCH 0 of 8] I/O topology patch kit Martin K. Petersen
2009-04-23 5:29 ` [PATCH 1 of 8] block: Expose stacked device queues in sysfs Martin K. Petersen
2009-04-23 5:29 ` Martin K. Petersen
2009-04-23 5:29 ` [PATCH 2 of 8] block: Export I/O topology for block devices and partitions Martin K. Petersen
2009-04-23 10:51 ` Jens Axboe
2009-04-23 11:49 ` Matthew Wilcox
2009-04-23 11:55 ` Jens Axboe
2009-04-23 13:22 ` Matthew Wilcox
2009-04-23 13:30 ` Matthew Wilcox
2009-04-23 13:17 ` Martin K. Petersen
2009-04-23 18:13 ` Konrad Rzeszutek
2009-04-23 18:26 ` Ric Wheeler
2009-04-23 18:44 ` Matthew Wilcox
2009-04-23 18:34 ` Martin K. Petersen
2009-04-23 5:29 ` [PATCH 3 of 8] MD: Use new topology calls to indicate alignment and I/O sizes Martin K. Petersen
2009-04-23 5:29 ` [PATCH 4 of 8] sd: Physical block size and alignment support Martin K. Petersen
2009-04-23 16:37 ` Konrad Rzeszutek
2009-04-23 18:25 ` Martin K. Petersen
2009-04-23 18:44 ` Konrad Rzeszutek
2009-04-23 19:02 ` Martin K. Petersen
2009-04-23 5:29 ` Martin K. Petersen
2009-04-23 5:29 ` [PATCH 5 of 8] sd: Detect non-rotational devices Martin K. Petersen
2009-04-23 10:52 ` Jens Axboe
2009-04-23 11:09 ` Jeff Garzik
2009-04-23 11:13 ` Jens Axboe
2009-04-23 11:22 ` Jeff Garzik
2009-04-23 11:38 ` Matthew Wilcox
2009-04-23 11:58 ` Jeff Garzik
2009-04-23 12:03 ` Jens Axboe
2009-04-23 13:16 ` Martin K. Petersen
2009-04-23 13:33 ` Jeff Garzik
2009-04-23 14:10 ` James Bottomley
2009-04-23 14:16 ` Matthew Wilcox
2009-04-23 14:39 ` Jeff Garzik
2009-04-23 17:25 ` Matthew Wilcox
2009-04-23 17:37 ` James Bottomley
2009-04-23 5:29 ` [PATCH 6 of 8] sd: Block limits VPD support Martin K. Petersen
2009-04-23 5:29 ` [PATCH 7 of 8] scsi_debug: Add support for physical block exponent and alignment Martin K. Petersen
2009-04-23 5:29 ` [PATCH 8 of 8] libata: Report disk alignment and physical block size Martin K. Petersen
2009-04-23 13:46 ` Matthew Wilcox
2009-04-23 14:05 ` Martin K. Petersen [this message]
2009-04-23 5:29 ` Martin K. Petersen
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