UBI: add UBI devices reference counting
This is one more step on the way to "removable" UBI devices. It
adds reference counting for UBI devices. Every time a volume on
this device is opened - the device's refcount is increased. It
is also increased if someone is reading any sysfs file of this
UBI device or of one of its volumes.
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index 7d32f71..bfc64c8 100644
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -1303,6 +1303,7 @@
* Make sure all the works which have been done in parallel are
* finished.
*/
+ ubi_assert(ubi->ref_count > 0);
down_write(&ubi->work_sem);
up_write(&ubi->work_sem);