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

[Matias BjÃrling]

On 6/22/19 3:02 AM, Damien Le Moal wrote:
> On 2019/06/21 22:07, Matias BjÃrling wrote:
> > From: Ajay Joshi <ajay.joshi@xxxxxxx>
> >
> > 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@xxxxxxx>
> > Signed-off-by: Matias BjÃrling <matias.bjorling@xxxxxxx>
> > ---
> >   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;
> > +	}
> >   }