On 07/20/2016 02:49 AM, Damien Le Moal wrote:
> Hi Hannes,
>
> On 7/19/16 22:25, Hannes Reinecke wrote:
>> We can map the RESET WRITE POINTER command onto a 'discard'
>> request.
>>
>> Signed-off-by: Hannes Reinecke <hare@xxxxxxx>
>> ---
>> drivers/scsi/sd.c | 65
>> ++++++++++++++++++++++++++++++++++++++++++++-----------
>> drivers/scsi/sd.h | 1 +
>> 2 files changed, 53 insertions(+), 13 deletions(-)
>>
>> diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
>> index 249ea81..52dda83 100644
>> --- a/drivers/scsi/sd.c
>> +++ b/drivers/scsi/sd.c
>> @@ -369,6 +369,7 @@ static const char *lbp_mode[] = {
>> [SD_LBP_WS16] = "writesame_16",
>> [SD_LBP_WS10] = "writesame_10",
>> [SD_LBP_ZERO] = "writesame_zero",
>> + [SD_ZBC_RESET_WP] = "reset_wp",
>> [SD_LBP_DISABLE] = "disabled",
>> };
>>
>> @@ -391,6 +392,13 @@ provisioning_mode_store(struct device *dev,
>> struct device_attribute *attr,
>> if (!capable(CAP_SYS_ADMIN))
>> return -EACCES;
>>
>> + if (sdkp->zoned == 1) {
>> + if (!strncmp(buf, lbp_mode[SD_ZBC_RESET_WP], 20)) {
>> + sd_config_discard(sdkp, SD_ZBC_RESET_WP);
>> + return count;
>> + }
>> + return -EINVAL;
>> + }
>> if (sdp->type != TYPE_DISK)
>> return -EINVAL;
>>
>> @@ -683,6 +691,11 @@ static void sd_config_discard(struct scsi_disk
>> *sdkp, unsigned int mode)
>> q->limits.discard_zeroes_data = sdkp->lbprz;
>> break;
>>
>> + case SD_ZBC_RESET_WP:
>> + max_blocks = sdkp->unmap_granularity;
>> + q->limits.discard_zeroes_data = 1;
>> + break;
>> +
>> case SD_LBP_ZERO:
>> max_blocks = min_not_zero(sdkp->max_ws_blocks,
>> (u32)SD_MAX_WS10_BLOCKS);
>
> I am still wondering if setting discard_zeroes_data to 1 is the right
> choice here since nothing will happen for conventional zones (no
> zeroing, no reset, nothing). discard_zeroes_data=0 may be a safer
> choice, even though I have not hit any issue with it set to 1.
>
This setting needs to be reviewed once hchs zero-out patches are in.
Thing is, we need to properly differentiate between 'discard' and
'zero-out'. Unfortunately ATM the libata stack only implements a
translation for 'write_same', which is then mapped onto DSM TRIM.
So the 'write_discard_zeroes' is even incorrect for current libata usage.
Cheers,
Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
hare@xxxxxxx +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)
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