dm table: fix DAX iterate_devices based device capability checks

commit 5b0fab50 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: 545ed20e ("dm: add infrastructure for DAX support")
Cc: stable@vger.kernel.org
Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
[jeffle: no dax write cache, no dax synchronous]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/md/dm-table.c

@@ -848,12 +848,12 @@ void dm_table_set_type(struct dm_table *t, unsigned type)
 }
 EXPORT_SYMBOL_GPL(dm_table_set_type);
 
-static int device_supports_dax(struct dm_target *ti, struct dm_dev *dev,
-			       sector_t start, sector_t len, void *data)
+static int device_not_dax_capable(struct dm_target *ti, struct dm_dev *dev,
+				  sector_t start, sector_t len, void *data)
 {
 	struct request_queue *q = bdev_get_queue(dev->bdev);
 
-	return q && blk_queue_dax(q);
+	return q && !blk_queue_dax(q);
 }
 
 static bool dm_table_supports_dax(struct dm_table *t)
@@ -869,7 +869,7 @@ static bool dm_table_supports_dax(struct dm_table *t)
 			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;
 	}