Re: [PATCH 2/4] null_blk: add zone open, close, and finish support

Matias Bjørling
2019-06-25T11:06:33Z

On 6/22/19 3:02 AM, Damien Le Moal wrote:
> On 2019/06/21 22:07, Matias Bjørling wrote:
>> From: Ajay Joshi <ajay.joshi@wdc.com>
>>
>> Implement REQ_OP_ZONE_OPEN, REQ_OP_ZONE_CLOSE and REQ_OP_ZONE_FINISH
>> support to allow explicit control of zone states.
>>
>> Signed-off-by: Ajay Joshi <ajay.joshi@wdc.com>
>> Signed-off-by: Matias Bjørling <matias.bjorling@wdc.com>
>> ---
>> drivers/block/null_blk.h | 4 ++--
>> drivers/block/null_blk_main.c | 13 ++++++++++---
>> drivers/block/null_blk_zoned.c | 33 ++++++++++++++++++++++++++++++---
>> 3 files changed, 42 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/block/null_blk.h b/drivers/block/null_blk.h
>> index 34b22d6523ba..62ef65cb0f3e 100644
>> --- a/drivers/block/null_blk.h
>> +++ b/drivers/block/null_blk.h
>> @@ -93,7 +93,7 @@ int null_zone_report(struct gendisk *disk, sector_t sector,
>> gfp_t gfp_mask);
>> void null_zone_write(struct nullb_cmd *cmd, sector_t sector,
>> unsigned int nr_sectors);
>> -void null_zone_reset(struct nullb_cmd *cmd, sector_t sector);
>> +void null_zone_mgmt_op(struct nullb_cmd *cmd, sector_t sector);
>> #else
>> static inline int null_zone_init(struct nullb_device *dev)
>> {
>> @@ -111,6 +111,6 @@ static inline void null_zone_write(struct nullb_cmd *cmd, sector_t sector,
>> unsigned int nr_sectors)
>> {
>> }
>> -static inline void null_zone_reset(struct nullb_cmd *cmd, sector_t sector) {}
>> +static inline void null_zone_mgmt_op(struct nullb_cmd *cmd, sector_t sector) {}
>> #endif /* CONFIG_BLK_DEV_ZONED */
>> #endif /* __NULL_BLK_H */
>> diff --git a/drivers/block/null_blk_main.c b/drivers/block/null_blk_main.c
>> index 447d635c79a2..5058fb980c9c 100644
>> --- a/drivers/block/null_blk_main.c
>> +++ b/drivers/block/null_blk_main.c
>> @@ -1209,10 +1209,17 @@ static blk_status_t null_handle_cmd(struct nullb_cmd *cmd)
>> nr_sectors = blk_rq_sectors(cmd->rq);
>> }
>>
>> - if (op == REQ_OP_WRITE)
>> + switch (op) {
>> + case REQ_OP_WRITE:
>> null_zone_write(cmd, sector, nr_sectors);
>> - else if (op == REQ_OP_ZONE_RESET)
>> - null_zone_reset(cmd, sector);
>> + break;
>> + case REQ_OP_ZONE_RESET:
>> + case REQ_OP_ZONE_OPEN:
>> + case REQ_OP_ZONE_CLOSE:
>> + case REQ_OP_ZONE_FINISH:
>> + null_zone_mgmt_op(cmd, sector);
>> + break;
>> + }
>> }
>> out:
>> /* Complete IO by inline, softirq or timer */
>> diff --git a/drivers/block/null_blk_zoned.c b/drivers/block/null_blk_zoned.c
>> index fca0c97ff1aa..47d956b2e148 100644
>> --- a/drivers/block/null_blk_zoned.c
>> +++ b/drivers/block/null_blk_zoned.c
>> @@ -121,17 +121,44 @@ void null_zone_write(struct nullb_cmd *cmd, sector_t sector,
>> }
>> }
>>
>> -void null_zone_reset(struct nullb_cmd *cmd, sector_t sector)
>> +void null_zone_mgmt_op(struct nullb_cmd *cmd, sector_t sector)
>> {
>> struct nullb_device *dev = cmd->nq->dev;
>> unsigned int zno = null_zone_no(dev, sector);
>> struct blk_zone *zone = &dev->zones[zno];
>> + enum req_opf op = req_op(cmd->rq);
>>
>> if (zone->type == BLK_ZONE_TYPE_CONVENTIONAL) {
>> cmd->error = BLK_STS_IOERR;
>> return;
>> }
>>
>> - zone->cond = BLK_ZONE_COND_EMPTY;
>> - zone->wp = zone->start;
>> + switch (op) {
>> + case REQ_OP_ZONE_RESET:
>> + zone->cond = BLK_ZONE_COND_EMPTY;
>> + zone->wp = zone->start;
>> + return;
>> + case REQ_OP_ZONE_OPEN:
>> + if (zone->cond == BLK_ZONE_COND_FULL) {
>> + cmd->error = BLK_STS_IOERR;
>> + return;
>> + }
>> + zone->cond = BLK_ZONE_COND_EXP_OPEN;
>
>
> With ZBC, open of a full zone is a "nop". No error. So I would rather have this as:
>
> if (zone->cond != BLK_ZONE_COND_FULL)
> zone->cond = BLK_ZONE_COND_EXP_OPEN;
>
Is this only ZBC? I can't find a reference to it in ZAC. I think it
should fail. One is trying to open a zone that is full, one can't open
it again. It's done for this round.
>
>> + return;
>> + case REQ_OP_ZONE_CLOSE:
>> + if (zone->cond == BLK_ZONE_COND_FULL) {
>> + cmd->error = BLK_STS_IOERR;
>> + return;
>> + }
>> + zone->cond = BLK_ZONE_COND_CLOSED;
>
> Sam as for open. Closing a full zone on ZBC is a nop.

I think this should cause error.

And the code above would
> also set an empty zone to closed. Finally, if the zone is open but nothing was
> written to it, it must be returned to empty condition, not closed.

Only on a reset event right? In general, if I do a expl. open, close it,
it should not go to empty.

So something
> like this is needed.
>
> switch (zone->cond) {
> case BLK_ZONE_COND_FULL:
> case BLK_ZONE_COND_EMPTY:
> break;
> case BLK_ZONE_COND_EXP_OPEN:
> if (zone->wp == zone->start) {
> zone->cond = BLK_ZONE_COND_EMPTY;
> break;
> }
> /* fallthrough */
> default:
> zone->cond = BLK_ZONE_COND_CLOSED;
> }
>
>> + return;
>> + case REQ_OP_ZONE_FINISH:
>> + zone->cond = BLK_ZONE_COND_FULL;
>> + zone->wp = zone->start + zone->len;
>> + return;
>> + default:
>> + /* Invalid zone condition */
>> + cmd->error = BLK_STS_IOERR;
>> + return;
>> + }
>> }
>>
>
>