[PATCH v3 3/7] dm: make dm aware of target's DAXDEV_RECOVERY capability

[Jane Chu]

If one of the MD raid participating target dax device supports
DAXDEV_RECOVERY, then it'll be declared on the whole that the
MD device is capable of DAXDEV_RECOVERY.
And only when the recovery process reaches to the target driver,
it becomes deterministic whether a certain dax address range
maybe recovered, or not.

Signed-off-by: Jane Chu <jane.chu@xxxxxxxxxx>
---
 drivers/md/dm-table.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index e43096cfe9e2..8af8a81b6172 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -844,6 +844,36 @@ static bool dm_table_supports_dax(struct dm_table *t,
 	return true;
 }
 
+/* Check whether device is capable of dax poison recovery */
+static int device_poison_recovery_capable(struct dm_target *ti,
+	struct dm_dev *dev, sector_t start, sector_t len, void *data)
+{
+	if (!dev->dax_dev)
+		return false;
+	return dax_recovery_capable(dev->dax_dev);
+}
+
+static bool dm_table_supports_poison_recovery(struct dm_table *t,
+	iterate_devices_callout_fn func)
+{
+	struct dm_target *ti;
+	unsigned int i;
+
+	/* Check if any DAX target supports poison recovery */
+	for (i = 0; i < dm_table_get_num_targets(t); i++) {
+		ti = dm_table_get_target(t, i);
+
+		if (!ti->type->direct_access)
+			return false;
+
+		if (ti->type->iterate_devices &&
+		    ti->type->iterate_devices(ti, func, NULL))
+			return true;
+	}
+
+	return false;
+}
+
 static int device_is_rq_stackable(struct dm_target *ti, struct dm_dev *dev,
 				  sector_t start, sector_t len, void *data)
 {
@@ -2014,6 +2044,9 @@ int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
 		blk_queue_flag_set(QUEUE_FLAG_DAX, q);
 		if (dm_table_supports_dax(t, device_not_dax_synchronous_capable))
 			set_dax_synchronous(t->md->dax_dev);
+		if (dm_table_supports_poison_recovery(t,
+					device_poison_recovery_capable))
+			set_dax_recovery(t->md->dax_dev);
 	}
 	else
 		blk_queue_flag_clear(QUEUE_FLAG_DAX, q);
-- 
2.18.4