MD: add sync_super to mddev_t struct

Add the 'sync_super' function pointer to MD array structure (struct mddev_s)

If device-mapper (dm-raid.c) is to define its own on-disk superblock and be
able to load it, there must still be a way for MD to initiate superblock
updates.  The simplest way to make this happen is to provide a pointer in
the MD array structure that can be set by device-mapper (or other module)
with a function to do this.  If the function has been set, it will be used;
otherwise, the method with be looked up via 'super_types' as usual.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>

2 files changed, 14 insertions, 2 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index d5385188c445..9160463b5f68 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1753,6 +1753,18 @@ static struct super_type super_types[] = {
         },
 };
 
+static void sync_super(mddev_t *mddev, mdk_rdev_t *rdev)
+{
+        if (mddev->sync_super) {
+                mddev->sync_super(mddev, rdev);
+                return;
+        }
+
+        BUG_ON(mddev->major_version >= ARRAY_SIZE(super_types));
+
+        super_types[mddev->major_version].sync_super(mddev, rdev);
+}
+
 static int match_mddev_units(mddev_t *mddev1, mddev_t *mddev2)
 {
         mdk_rdev_t *rdev, *rdev2;
@@ -2171,8 +2183,7 @@ static void sync_sbs(mddev_t * mddev, int nospares)
                         /* Don't update this superblock */
                         rdev->sb_loaded = 2;
                 } else {
-                        super_types[mddev->major_version].
-                                sync_super(mddev, rdev);
+                        sync_super(mddev, rdev);
                         rdev->sb_loaded = 1;
                 }
         }
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 0b1fd3f1d85b..5e35535ab7c3 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -330,6 +330,7 @@ struct mddev_s
         atomic_t flush_pending;
         struct work_struct flush_work;
         struct work_struct event_work;  /* used by dm to report failure event */
+        void (*sync_super)(mddev_t *mddev, mdk_rdev_t *rdev);
 };