From: Douglas Gilbert <dgilbert@interlog.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: linux-scsi@vger.kernel.org, linux-ide@vger.kernel.org,
linux-kernel@vger.kernel.org, liml@rtr.ca, jens.axboe@oracle.com,
matthew@wil.cx, dwmw2@infradead.org
Subject: Re: [PATCH 4/7] sd: add support for WRITE SAME (16) with unmap bit
Date: Sat, 29 Aug 2009 22:43:44 -0400 [thread overview]
Message-ID: <4A99E760.1060302@interlog.com> (raw)
In-Reply-To: <20090830010500.GA24395@infradead.org>
Christoph Hellwig wrote:
> On Sat, Aug 29, 2009 at 08:43:27PM -0400, Douglas Gilbert wrote:
>>> + if (buffer[14] & 0x80)
>>> + sdkp->thin_provisioning = 1;
>>> +
>> So you are checking the TPE bit (Thin Provisioning Enabled) but
>> not the TPRZ bit (Thin Provisioning Read Zeros). Shouldn't
>> there also be a sdkp->thin_provisioning_read_zeros bit defined
>> in struct scsi_disk?
>>
>> Is your application well defined when TPRZ==0 ?
>
> Filesystems do not care if these blocks are in a defined state, as
> they must never return the content of uninitilized blocks to userspace.
> Now if we do want to support discard through raid arrays we might start
> to care, and will have check the TPRZ bit.
Another reason to note the TPRZ bit is that if it is 1 then
the data given to WRITE SAME (16 and 32) must be a logical
block of zeros for the UNMAP bit to be honoured (sbc3r19.pdf
section 4.6.3.2 last paragraph).
next prev parent reply other threads:[~2009-08-30 2:43 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-08-29 23:03 [PATCH 0/7] discard support revisited Christoph Hellwig
2009-08-29 23:03 ` [PATCH 1/7] Make DISCARD_BARRIER and DISCARD_NOBARRIER writes instead of reads Christoph Hellwig
2009-09-03 17:52 ` David Woodhouse
2009-09-03 17:56 ` Matthew Wilcox
2009-08-29 23:03 ` [PATCH 2/7] block: use blkdev_issue_discard in blk_ioctl_discard Christoph Hellwig
2009-09-01 9:06 ` Steven Whitehouse
2009-09-11 22:26 ` Christoph Hellwig
2009-09-14 9:40 ` Jens Axboe
2009-08-29 23:03 ` [PATCH 3/7] block: discard may need to allocate pages Christoph Hellwig
2009-08-29 23:03 ` [PATCH 4/7] sd: add support for WRITE SAME (16) with unmap bit Christoph Hellwig
2009-08-30 0:43 ` Douglas Gilbert
2009-08-30 1:05 ` Christoph Hellwig
2009-08-30 2:43 ` Douglas Gilbert [this message]
2009-08-30 2:48 ` Christoph Hellwig
2009-08-30 11:12 ` Sergei Shtylyov
2009-08-30 17:14 ` Christoph Hellwig
2009-08-29 23:03 ` [PATCH 5/7] libata: Add support for TRIM Christoph Hellwig
2009-08-29 23:03 ` [PATCH 6/7] block: allow large discard requests Christoph Hellwig
2009-08-30 2:49 ` Mark Lord
2009-08-30 2:50 ` Matthew Wilcox
2009-08-30 2:52 ` Mark Lord
2009-08-30 2:56 ` Christoph Hellwig
2009-08-29 23:03 ` [PATCH 7/7] xfs: add batches discard support Christoph Hellwig
2009-08-29 23:37 ` [PATCH 0/7] discard support revisited Matthew Wilcox
2009-08-30 2:15 ` Christoph Hellwig
2009-08-30 3:03 ` Matthew Wilcox
2009-08-30 20:17 ` James Bottomley
2009-08-30 21:42 ` Matthew Wilcox
2009-08-30 22:48 ` Christoph Hellwig
2009-09-02 19:46 ` Matthew Wilcox
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