Re: [PATCH v6 0/4] SCT Write Same

[Hannes Reinecke]

On 08/22/2016 06:23 AM, Shaun Tancheff wrote:
> At some point the method of issuing Write Same for ATA drives changed.
> Currently write same is commonly available via SCT so expose the SCT
> capabilities and use SCT Write Same when it is available.
> 
> This is useful for zoned based media that prefers to support discard
> with lbprz set, aka discard zeroes data by mapping discard operations to
> reset write pointer operations. Conventional zones that do not support
> reset write pointer can still honor the discard zeroes data by issuing
> a write same over the zone.
> 
> It may also be nice to know if various controllers that currently
> disable WRITE SAME will work with the SCT Write Same code path:
>   aacraid, arcmsr, megaraid, 3w-9xxx, 3w-sas, 3w-xxxx, gdth, hpsa, ips,
>   megaraid, pmcraid, storvsc_drv
> 
> This patch against v4.8-rc2 is also at
>     https://github.com/stancheff/linux/tree/v4.8-rc2%2Bbiof.v9
> 
>     git@xxxxxxxxxx:stancheff/linux.git v4.8-rc2+biof.v9
> 
> v6:
>  - Fix bisect bug reported by Tom Yan <tom.ty89@xxxxxxxxx>
>  - Change to use sg_copy_from_buffer as per Christoph Hellwig <hch@xxxxxx>
>  - Added support for a sector_size descriptor other than 512 bytes.
> v5:
>  - Addressed review comments
>  - Report support for ZBC only for zoned devices.
>  - kmap page during rewrite
>  - Fix unmap set to require trim or error, if not unmap then sct write
>    same or error.
> v4:
>  - Added partial MAINTENANCE_IN opcode simulation
>  - Dropped all changes in drivers/scsi/*
>  - Changed to honor the UNMAP flag -> TRIM, no UNMAP -> SCT.
> v3:
>  - Demux UNMAP/TRIM from WRITE SAME
> v2:
>  - Remove fugly ata hacking from sd.c
> 
> Shaun Tancheff (4):
>   libata: Safely overwrite attached page in WRITE SAME xlat
>   Add support for SCT Write Same
>   SCT Write Same / DSM Trim
>   SCT Write Same handle ATA_DFLAG_PIO
> 
>  drivers/ata/libata-scsi.c | 280 +++++++++++++++++++++++++++++++++++++++++-----
>  include/linux/ata.h       |  69 +++++++-----
>  2 files changed, 292 insertions(+), 57 deletions(-)
> 
Thanks for doing this.
It has been on my To-Do list for a long time, and it's good to see the
UNMAP/TRIM SATL cleaned up finally.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
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