From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: Christoph Hellwig <hch@lst.de>, Tejun Heo <tj@kernel.org>
Cc: martin.petersen@oracle.com, axboe@kernel.dk,
linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org,
linux-block@vger.kernel.org
Subject: Re: support ranges TRIM for libata
Date: Thu, 23 Mar 2017 09:47:41 -0400 [thread overview]
Message-ID: <1490276861.2202.8.camel@HansenPartnership.com> (raw)
In-Reply-To: <20170322181947.GA4733@lst.de>
On Wed, 2017-03-22 at 19:19 +0100, Christoph Hellwig wrote:
> On Tue, Mar 21, 2017 at 02:59:01PM -0400, Tejun Heo wrote:
> > I do like the fact that this is a lot simpler than the previous
> > implementation but am not quite sure we want to deviate
> > significantly from what we do for other commands (command
> > translation). Is it because fixing the existing implementation
> > would involve invaisve changes including memory allocations?
>
> The current implementation already has the issue of that it does
> corrupt user data reliably if the using SG_IO for WRITE SAME
> commands.
That does need fixing.
> Doing ranges using translation would turn into a nightmare because
> ATA TRIM ranges are 16 bits long while SCSI UNAMP ranges are 32-bit,
> so we effectively can't translated them without introducing a
> non-standard hook between libata and scsi to communicate that
> limit.
Why can't we do what the t10 sat document recommends: if the ATA device
doesn't support the XL version (32 bit ranges) then translate unmap to
multiple non-XL commands?
I don't necessarily object to the vendor specific 1<->1 approach, it's
just it won't fix the problem you cited above (SG_IO WRITE SAME), its
just that now we error the command, which may cause some surprise. I
also wonder if we couldn't simply do an ATA_16 TRIM if we're already
going to all the trouble of recognising ATA devices in the sd discard
path?
James
> And once we're down that path we might as well just do the
> right thing directly.
next prev parent reply other threads:[~2017-03-23 13:47 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-20 20:43 support ranges TRIM for libata Christoph Hellwig
2017-03-20 20:43 ` [PATCH 1/7] ѕd: split sd_setup_discard_cmnd Christoph Hellwig
2017-03-27 22:24 ` Bart Van Assche
2017-03-28 14:05 ` axboe
2017-03-30 8:49 ` hch
2017-03-20 20:43 ` [PATCH 2/7] sd: provide a new ata trim provisioning mode Christoph Hellwig
2017-03-27 22:40 ` Bart Van Assche
2017-03-20 20:43 ` [PATCH 3/7] libata: remove SCT WRITE SAME support Christoph Hellwig
2017-03-20 20:43 ` [PATCH 4/7] libata: simplify the trim implementation Christoph Hellwig
2017-03-20 20:43 ` [PATCH 5/7] block: add a max_discard_segment_size queue limit Christoph Hellwig
2017-03-27 23:09 ` Bart Van Assche
2017-03-20 20:43 ` [PATCH 6/7] sd: support multi-range TRIM for ATA disks Christoph Hellwig
2017-03-27 23:38 ` Bart Van Assche
2017-03-20 20:43 ` [PATCH 7/7] sd: use ZERO_PAGE for WRITE_SAME payloads Christoph Hellwig
2017-03-27 23:40 ` Bart Van Assche
2017-03-21 18:59 ` support ranges TRIM for libata Tejun Heo
2017-03-22 18:19 ` Christoph Hellwig
2017-03-23 13:47 ` James Bottomley [this message]
2017-03-23 13:55 ` Christoph Hellwig
2017-03-23 14:35 ` James Bottomley
2017-03-23 14:43 ` Christoph Hellwig
2017-03-23 15:04 ` Tejun Heo
2017-03-23 15:27 ` Christoph Hellwig
2017-03-23 15:30 ` Christoph Hellwig
2017-03-23 15:39 ` Martin K. Petersen
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