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From:   Pankaj Raghav <p.raghav@samsung.com>
To:     Johannes.Thumshirn@wdc.com, snitzer@kernel.org, axboe@kernel.dk,
        damien.lemoal@opensource.wdc.com, agk@redhat.com, hch@lst.de
Cc:     dm-devel@redhat.com, matias.bjorling@wdc.com, gost.dev@samsung.com,
        linux-kernel@vger.kernel.org, pankydev8@gmail.com,
        jaegeuk@kernel.org, hare@suse.de, linux-block@vger.kernel.org,
        linux-nvme@lists.infradead.org, bvanassche@acm.org,
        Pankaj Raghav <p.raghav@samsung.com>
Subject: [PATCH v9 12/13] dm: introduce DM_EMULATED_ZONES target type
Date:   Wed,  3 Aug 2022 11:48:00 +0200
Message-Id: <20220803094801.177490-13-p.raghav@samsung.com>
In-Reply-To: <20220803094801.177490-1-p.raghav@samsung.com>
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References: <20220803094801.177490-1-p.raghav@samsung.com>
        <CGME20220803094815eucas1p2dfab477daf4f2eb05342d756fdf7f14d@eucas1p2.samsung.com>
Precedence: bulk

Introduce a new target type DM_EMULATED_ZONES for targets with
a different zone number of sectors than the underlying device zone
number of sectors.

This target type is introduced as the existing zoned targets assume
that the target and the underlying device have the same zone
number of sectors. The new target: dm-po2zone will use this new target
type as it emulates the zone boundary that is different from the
underlying zoned device.

Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
---
 drivers/md/dm-table.c         | 13 ++++++++++---
 include/linux/device-mapper.h |  9 +++++++++
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 31eb1d29d136..b37991ea3ffb 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1614,13 +1614,20 @@ static bool dm_table_supports_zoned_model(struct dm_table *t,
 	return true;
 }
 
-static int device_not_matches_zone_sectors(struct dm_target *ti, struct dm_dev *dev,
+/*
+ * Callback function to check for device zone sector across devices. If the
+ * DM_TARGET_EMULATED_ZONES target feature flag is not set, then the target
+ * should have the same zone sector as the underlying devices.
+ */
+static int check_valid_device_zone_sectors(struct dm_target *ti, struct dm_dev *dev,
 					   sector_t start, sector_t len, void *data)
 {
 	unsigned int *zone_sectors = data;
 
-	if (!bdev_is_zoned(dev->bdev))
+	if (!bdev_is_zoned(dev->bdev) ||
+	    dm_target_supports_emulated_zones(ti->type))
 		return 0;
+
 	return bdev_zone_sectors(dev->bdev) != *zone_sectors;
 }
 
@@ -1645,7 +1652,7 @@ static int validate_hardware_zoned_model(struct dm_table *t,
 	if (!zone_sectors)
 		return -EINVAL;
 
-	if (dm_table_any_dev_attr(t, device_not_matches_zone_sectors, &zone_sectors)) {
+	if (dm_table_any_dev_attr(t, check_valid_device_zone_sectors, &zone_sectors)) {
 		DMERR("%s: zone sectors is not consistent across all zoned devices",
 		      dm_device_name(t->md));
 		return -EINVAL;
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 04c6acf7faaa..83e20de264c9 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -294,6 +294,15 @@ struct target_type {
 #define dm_target_supports_mixed_zoned_model(type) (false)
 #endif
 
+#ifdef CONFIG_BLK_DEV_ZONED
+#define DM_TARGET_EMULATED_ZONES	0x00000400
+#define dm_target_supports_emulated_zones(type) \
+	((type)->features & DM_TARGET_EMULATED_ZONES)
+#else
+#define DM_TARGET_EMULATED_ZONES	0x00000000
+#define dm_target_supports_emulated_zones(type) (false)
+#endif
+
 struct dm_target {
 	struct dm_table *table;
 	struct target_type *type;
-- 
2.25.1