[PATCH 4.14 08/20] dm table: fix DAX iterate_devices based device capability checks

[gregkh]

From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

From: Jeffle Xu <jefflexu@xxxxxxxxxxxxxxxxx>

commit 5b0fab508992c2e120971da658ce80027acbc405 upstream.

Fix dm_table_supports_dax() and invert logic of both
iterate_devices_callout_fn so that all devices' DAX capabilities are
properly checked.

Fixes: 545ed20e6df6 ("dm: add infrastructure for DAX support")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Jeffle Xu <jefflexu@xxxxxxxxxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
[jeffle: no dax synchronous]
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/md/dm-table.c |   25 ++++---------------------
 1 file changed, 4 insertions(+), 21 deletions(-)

--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -889,10 +889,10 @@ void dm_table_set_type(struct dm_table *
 }
 EXPORT_SYMBOL_GPL(dm_table_set_type);
 
-static int device_supports_dax(struct dm_target *ti, struct dm_dev *dev,
+static int device_not_dax_capable(struct dm_target *ti, struct dm_dev *dev,
 			       sector_t start, sector_t len, void *data)
 {
-	return bdev_dax_supported(dev->bdev, PAGE_SIZE);
+	return !bdev_dax_supported(dev->bdev, PAGE_SIZE);
 }
 
 static bool dm_table_supports_dax(struct dm_table *t)
@@ -908,7 +908,7 @@ static bool dm_table_supports_dax(struct
 			return false;
 
 		if (!ti->type->iterate_devices ||
-		    !ti->type->iterate_devices(ti, device_supports_dax, NULL))
+		    ti->type->iterate_devices(ti, device_not_dax_capable, NULL))
 			return false;
 	}
 
@@ -1690,23 +1690,6 @@ static int device_dax_write_cache_enable
 	return false;
 }
 
-static int dm_table_supports_dax_write_cache(struct dm_table *t)
-{
-	struct dm_target *ti;
-	unsigned i;
-
-	for (i = 0; i < dm_table_get_num_targets(t); i++) {
-		ti = dm_table_get_target(t, i);
-
-		if (ti->type->iterate_devices &&
-		    ti->type->iterate_devices(ti,
-				device_dax_write_cache_enabled, NULL))
-			return true;
-	}
-
-	return false;
-}
-
 static int device_is_rotational(struct dm_target *ti, struct dm_dev *dev,
 				sector_t start, sector_t len, void *data)
 {
@@ -1854,7 +1837,7 @@ void dm_table_set_restrictions(struct dm
 	else
 		queue_flag_clear_unlocked(QUEUE_FLAG_DAX, q);
 
-	if (dm_table_supports_dax_write_cache(t))
+	if (dm_table_any_dev_attr(t, device_dax_write_cache_enabled))
 		dax_write_cache(t->md->dax_dev, true);
 
 	/* Ensure that all underlying devices are non-rotational. */