UBI: add notification API

UBI volume notifications are intended to create the API to get clients
notified about volume creation/deletion, renaming and re-sizing. A
client can subscribe to these notifications using 'ubi_volume_register()'
and cancel the subscription using 'ubi_volume_unregister()'. When UBI
volumes change, a blocking notifier is called. Clients also can request
"added" events on all volumes that existed before client subscribed
to the notifications.

If we use notifications instead of calling functions like 'ubi_gluebi_xxx()',
we can make the MTD emulation layer to be more flexible: build it as a
separate module and load/unload it on demand.

[Artem: many cleanups, rework locking, add "updated" event, provide
 device/volume info in notifiers]

Signed-off-by: Dmitry Pervushin <dpervushin@embeddedalley.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index 6d929329a8d5..86e1a4e0ab01 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -38,6 +38,7 @@
 #include <linux/vmalloc.h>
 #include <linux/mtd/mtd.h>
 #include <linux/mtd/ubi.h>
+#include <linux/notifier.h>
 
 #include "ubi-media.h"
 #include "scan.h"
@@ -483,6 +484,7 @@ extern const struct file_operations ubi_cdev_operations;
 extern const struct file_operations ubi_vol_cdev_operations;
 extern struct class *ubi_class;
 extern struct mutex ubi_devices_mutex;
+extern struct blocking_notifier_head ubi_notifiers;
 
 /* vtbl.c */
 int ubi_change_vtbl_record(struct ubi_device *ubi, int idx,
@@ -575,6 +577,16 @@ struct ubi_device *ubi_get_device(int ubi_num);
 void ubi_put_device(struct ubi_device *ubi);
 struct ubi_device *ubi_get_by_major(int major);
 int ubi_major2num(int major);
+int ubi_volume_notify(struct ubi_device *ubi, struct ubi_volume *vol,
+                      int ntype);
+int ubi_notify_all(struct ubi_device *ubi, int ntype,
+                   struct notifier_block *nb);
+int ubi_enumerate_volumes(struct notifier_block *nb);
+
+/* kapi.c */
+void ubi_do_get_device_info(struct ubi_device *ubi, struct ubi_device_info *di);
+void ubi_do_get_volume_info(struct ubi_device *ubi, struct ubi_volume *vol,
+                            struct ubi_volume_info *vi);
 
 /*
  * ubi_rb_for_each_entry - walk an RB-tree.