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>

1 files changed, 8 insertions, 1 deletions

diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index 21c028366fd..91fde0e8ff5 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -245,6 +245,7 @@ struct ubi_wl_entry;
  *                @beb_rsvd_level, @bad_peb_count, @good_peb_count, @vol_count,
  *                @vol->readers, @vol->writers, @vol->exclusive,
  *                @vol->ref_count, @vol->mapping and @vol->eba_tbl.
+ * @ref_count: count of references on the UBI device
  *
  * @rsvd_pebs: count of reserved physical eraseblocks
  * @avail_pebs: count of available physical eraseblocks
@@ -325,6 +326,7 @@ struct ubi_device {
         int vol_count;
         struct ubi_volume *volumes[UBI_MAX_VOLUMES+UBI_INT_VOL_COUNT];
         spinlock_t volumes_lock;
+        int ref_count;
 
         int rsvd_pebs;
         int avail_pebs;
@@ -401,7 +403,6 @@ extern struct kmem_cache *ubi_wl_entry_slab;
 extern struct file_operations ubi_ctrl_cdev_operations;
 extern struct file_operations ubi_cdev_operations;
 extern struct file_operations ubi_vol_cdev_operations;
-extern struct ubi_device *ubi_devices[];
 extern struct class *ubi_class;
 
 /* vtbl.c */
@@ -479,6 +480,12 @@ int ubi_io_read_vid_hdr(struct ubi_device *ubi, int pnum,
 int ubi_io_write_vid_hdr(struct ubi_device *ubi, int pnum,
                          struct ubi_vid_hdr *vid_hdr);
 
+/* build.c */
+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);
+
 /*
  * ubi_rb_for_each_entry - walk an RB-tree.
  * @rb: a pointer to type 'struct rb_node' to to use as a loop counter