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;
+
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
+#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;
--
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