On 6/17/22 14:45, Pankaj Raghav wrote:
> On 2022-06-17 01:49, Damien Le Moal wrote:
>>>> Why do you need to change dm_set_zones_restrictions() at all ?
>>>>
>>> When the device mapper is created, the q->limits gets inherited from the
>>> underlying device. The chunk sectors of the target and the device will
>>> be the same but we want the chunk sector of the target to be different
>>> (rounded to po2) compared to the underlying device's chunk sector. This
>>> needs to be done only for the dm-po2z target and not for other targets
>>> that uses npo2 zoned devices (like dm-linear). So to perform this
>>> operation in a target independent way in dm-zone.c, I chose to always
>>> revalidate npo2 zoned device and update the chunk sector and nr_zones in
>>> dm_zone_revalidate_cb based on the zone information from the target.
>>> This allows to set the limits correctly for dm-po2z target.
>>
>> But DM revalidate will be called for the target AFTER it is setup (after
>> its gendisk is added). So how can DM revalidate see the incorrect zone
>> size ? If that is the case, then the target constructor is broken or
>> missing something. DM revalidate zone is generic and only allocates the
>> zone bitmaps for the target device. There should be not need at all to
>> touch that function.
>>
> I think this is a cleaner approach using features flag and io_hints
> instead of messing with the revalidate zone function:
>
> diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
> index 135c0cc190fb..c97a71e0473f 100644
> --- a/drivers/md/dm-table.c
> +++ b/drivers/md/dm-table.c
> @@ -1618,6 +1618,9 @@ static int device_not_matches_zone_sectors(struct
> dm_target *ti, struct dm_dev *
> if (!blk_queue_is_zoned(q))
> return 0;
>
> + if(dm_target_supports_emulated_zone_size(ti->type))
> + return 0;
> +
This should be in validate_hardware_zoned_model(), not here.
> return blk_queue_zone_sectors(q) != *zone_sectors;
> }
>
> diff --git a/drivers/md/dm-zoned-npo2-target.c
> b/drivers/md/dm-zoned-npo2-target.c
> index dad135964e09..b203be808f09 100644
> --- a/drivers/md/dm-zoned-npo2-target.c
> +++ b/drivers/md/dm-zoned-npo2-target.c
> @@ -187,6 +187,12 @@ static int dmz_npo2_end_io(struct dm_target *ti,
> struct bio *bio,
> return DM_ENDIO_DONE;
> }
>
> +static void dmz_npo2_io_hints(struct dm_target *ti, struct queue_limits
> *limits)
> +{
> + struct dmz_npo2_target *dmh = ti->private;
> + limits->chunk_sectors = dmh->zsze_po2;
> +}
> +
> static int dmz_npo2_map(struct dm_target *ti, struct bio *bio)
> {
> struct dmz_npo2_target *dmh = ti->private;
> @@ -233,12 +239,13 @@ static int dmz_npo2_iterate_devices(struct
> dm_target *ti,
> static struct target_type dmz_npo2_target = {
> .name = "zoned-npo2",
> .version = { 1, 0, 0 },
> - .features = DM_TARGET_ZONED_HM,
> + .features = DM_TARGET_ZONED_HM | DM_TARGET_EMULATED_ZONE_SIZE,
> .map = dmz_npo2_map,
> .end_io = dmz_npo2_end_io,
> .report_zones = dmz_npo2_report_zones,
> .iterate_devices = dmz_npo2_iterate_devices,
> .module = THIS_MODULE,
> + .io_hints = dmz_npo2_io_hints,
> .ctr = dmz_npo2_ctr,
> };
>
> diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
> index c2a3758c4aaa..9f3a4d98a22a 100644
> --- a/include/linux/device-mapper.h
> +++ b/include/linux/device-mapper.h
> @@ -283,6 +283,15 @@ struct target_type {
> #define dm_target_supports_mixed_zoned_model(type) (false)
> #endif
>
> +#ifdef CONFIG_BLK_DEV_ZONED
> +#define DM_TARGET_EMULATED_ZONE_SIZE 0x00000400
Make it general: DM_TARGET_EMULATED_ZONES
> +#define dm_target_supports_emulated_zone_size(type) \
> + ((type)->features & DM_TARGET_EMULATED_ZONE_SIZE)
> +#else
> +#define DM_TARGET_EMULATED_ZONE_SIZE 0x00000000
> +#define dm_target_supports_emulated_zone_size(type) (false)
> +#endif
> +
> struct dm_target {
> struct dm_table *table;
> struct target_type *type;
>
--
Damien Le Moal
Western Digital Research
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