lkml.org 
[lkml]   [2014]   [Oct]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH 0/3] scsi: Add Hyper-V logical block provisioning quirks
From
On 23 October 2014 02:50, Martin K. Petersen <martin.petersen@oracle.com> wrote:
>>>>>> "Sitsofe" == Sitsofe Wheeler <sitsofe@gmail.com> writes:
>
> Sitsofe> 2. On top of the above, when a disk is "small" (has less than
> Sitsofe> 2^32 sectors which is typically < 2 TBytes in size) READ
> Sitsofe> CAPACITY(16) won't be triggered.
>
> static int sd_try_rc16_first(struct scsi_device *sdp)
> {
> if (sdp->host->max_cmd_len < 16)
> return 0;
> if (sdp->try_rc_10_first)
> return 0;
> if (sdp->scsi_level > SCSI_SPC_2)
> return 1;
> if (scsi_device_protection(sdp))
> return 1;
> return 0;
> }

Yes but since SCSI_SPC_2 was being advertised by the Hyper-V virtual
disk (and presumably device protection isn't advertised either) this
function was returning 0. That's why the patch in
https://lkml.org/lkml/2014/10/10/49 added yet another quirk. If if
SPC_3 were correctly advertised on Hyper-V virtual disks would
TRY_VPD_PAGES still be needed to cope correctly with passthrough
disks?

What I didn't realise was that the TRY_VPD_PAGES quirk was purely to
fix WRITE_SAME Hyper-V issues and not to address anything thin
provisioning related. Having said that, why was the TRY_VPD_PAGES
quirk back-ported 3.14 without any users -
https://lkml.org/lkml/2014/9/15/733 ?

--
Sitsofe | http://sucs.org/~sits/


\
 
 \ /
  Last update: 2014-10-23 11:41    [W:0.266 / U:0.172 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site