md: dm-raid should call helper function to clear rdev.

dm-raid currently open-codes the freeing of some members of
and rdev.  It is more maintainable to have it call common code
from md.c which does this for all call-sites.

So remove free_disk_sb to md_rdev_clear, export it, and use it in
dm-raid.c
Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/dm-raid.c

@@ -155,10 +155,7 @@ static void context_free(struct raid_set *rs)
 	for (i = 0; i < rs->md.raid_disks; i++) {
 		if (rs->dev[i].meta_dev)
 			dm_put_device(rs->ti, rs->dev[i].meta_dev);
-		if (rs->dev[i].rdev.sb_page)
-			put_page(rs->dev[i].rdev.sb_page);
-		rs->dev[i].rdev.sb_page = NULL;
-		rs->dev[i].rdev.sb_loaded = 0;
+		md_rdev_clear(&rs->dev[i].rdev);
 		if (rs->dev[i].data_dev)
 			dm_put_device(rs->ti, rs->dev[i].data_dev);
 	}

drivers/md/md.c

@@ -803,7 +803,7 @@ static int alloc_disk_sb(struct md_rdev * rdev)
 	return 0;
 }
 
-static void free_disk_sb(struct md_rdev * rdev)
+void md_rdev_clear(struct md_rdev *rdev)
 {
 	if (rdev->sb_page) {
 		put_page(rdev->sb_page);
@@ -817,7 +817,7 @@ static void free_disk_sb(struct md_rdev * rdev)
 		rdev->bb_page = NULL;
 	}
 }
-
+EXPORT_SYMBOL_GPL(md_rdev_clear);
 
 static void super_written(struct bio *bio, int error)
 {
@@ -2244,7 +2244,7 @@ static void export_rdev(struct md_rdev * rdev)
 		bdevname(rdev->bdev,b));
 	if (rdev->mddev)
 		MD_BUG();
-	free_disk_sb(rdev);
+	md_rdev_clear(rdev);
 #ifndef MODULE
 	if (test_bit(AutoDetected, &rdev->flags))
 		md_autodetect_dev(rdev->bdev->bd_dev);
@@ -3324,7 +3324,7 @@ static struct md_rdev *md_import_device(dev_t newdev, int super_format, int supe
 abort_free:
 	if (rdev->bdev)
 		unlock_rdev(rdev);
-	free_disk_sb(rdev);
+	md_rdev_clear(rdev);
 	kfree(rdev->badblocks.page);
 	kfree(rdev);
 	return ERR_PTR(err);

drivers/md/md.h

@@ -619,6 +619,7 @@ extern int md_run(struct mddev *mddev);
 extern void md_stop(struct mddev *mddev);
 extern void md_stop_writes(struct mddev *mddev);
 extern int md_rdev_init(struct md_rdev *rdev);
+extern void md_rdev_clear(struct md_rdev *rdev);
 
 extern void mddev_suspend(struct mddev *mddev);
 extern void mddev_resume(struct mddev *mddev);