Re: [PATCH 3/4] zbd: finish zone when all random write target zones have small remainder

On 4/11/25 8:12 PM, Shin'ichiro Kawasaki wrote:
> When a random write target offset points to a zone that is not writable,
> zbd_convert_to_write_zone() attempts to convert the write offset to a
> different, writable zone. However, the conversion fails when all of the
> following conditions are met:
> 
> 1) the workload has the max_open_zones limit
> 2) every write target zones, up to the max_open_zones limit, has
>    remainder sectors smaller than the block size
> 3) the next random write request targets a zone not in the write target
>    zone list
> 
> In this case, zbd_convert_to_write_zone() can not open another zone
> without exceeding the max_open_zones constraint. Therefore, It does not
> convert the write to a different zone printing with the debug message
> "did not choose another write zone". This leads to an unexpected stop of
> the random write workload.
> 
> To prevent the unexpected write stop, finish one of the write target
> zones with small remainder sectors. Check if all write target zones have
> small remainder, and store the result in the new local boolean variable
> all_write_zones_have_small_remainder. When this condition is true,
> choose one of the write target zones and finish it. Then return the zone
> from zbd_convert_to_write_zone() enabling the write process to continue.
> 
> Signed-off-by: Shin'ichiro Kawasaki <[email protected]>

Looks good to me.

Reviewed-by: Damien Le Moal <[email protected]>

-- 
Damien Le Moal
Western Digital Research