Re: [PATCH v2 1/3] dm zoned: back off when reclaim finds no destination zone

[Damien Le Moal <dlemoal@kernel.org>]

On 2026/10/10 18:16, illofspeed wrote:
> When dmz_do_reclaim() fails with -ENOSPC because no free zone is
> available to copy the data into, dmz_reclaim_work() still ends with
> dmz_schedule_reclaim(). If the target is idle, dmz_should_reclaim()
> keeps returning true, the work is queued again with no delay and the
> worker spins on the same failing pass.
> 
> Re-arm the idle poll instead, so that reclaim is retried after
> DMZ_IDLE_PERIOD. The next patch makes -ENOSPC the expected result when
> an idle target has random zones but no free sequential zone.
> 
> Tested on a 7.2.6 kernel as an out-of-tree dm-zoned module, together
> with the next two patches, on emulated host-managed drives (tcmu-runner
> ZBC handler) and on three 27 TB host-managed drives used as md RAID5
> members.
> 
> Assisted-by: LLM
> Signed-off-by: illofspeed <illofspeed@gmail.com>

Patch looks OK, but is "ilofspeed" your full name?

> ---
>  drivers/md/dm-zoned-reclaim.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/md/dm-zoned-reclaim.c b/drivers/md/dm-zoned-reclaim.c
> index c041413c729..315f0da99f3 100644
> --- a/drivers/md/dm-zoned-reclaim.c
> +++ b/drivers/md/dm-zoned-reclaim.c
> @@ -540,6 +540,14 @@ static void dmz_reclaim_work(struct work_struct *work)
>  	if (ret && ret != -EINTR) {
>  		if (!dmz_check_dev(zmd))
>  			return;
> +		if (ret == -ENOSPC) {
> +			/*
> +			 * No zone to copy into: nothing can progress now.
> +			 * Rescheduling immediately would spin; poll instead.
> +			 */
> +			mod_delayed_work(zrc->wq, &zrc->work, DMZ_IDLE_PERIOD);
> +			return;
> +		}
>  	}
>  
>  	dmz_schedule_reclaim(zrc);


-- 
Damien Le Moal
Western Digital Research