dm persistent data: tidy transaction manager creation fns

Tidy the transaction manager creation functions.

They no longer lock the superblock.  Superblock locking is pulled out to
the caller.

Also export dm_bm_write_lock_zero.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/persistent-data/dm-transaction-manager.h b/drivers/md/persistent-data/dm-transaction-manager.h
index 6da7848..b5b1390 100644
--- a/drivers/md/persistent-data/dm-transaction-manager.h
+++ b/drivers/md/persistent-data/dm-transaction-manager.h
@@ -115,16 +115,17 @@
  *
  * Returns a tm that has an open transaction to write the new disk sm.
  * Caller should store the new sm root and commit.
+ *
+ * The superblock location is passed so the metadata space map knows it
+ * shouldn't be used.
  */
 int dm_tm_create_with_sm(struct dm_block_manager *bm, dm_block_t sb_location,
-			 struct dm_block_validator *sb_validator,
 			 struct dm_transaction_manager **tm,
-			 struct dm_space_map **sm, struct dm_block **sblock);
+			 struct dm_space_map **sm);
 
 int dm_tm_open_with_sm(struct dm_block_manager *bm, dm_block_t sb_location,
-		       struct dm_block_validator *sb_validator,
-		       size_t root_offset, size_t root_max_len,
+		       void *sm_root, size_t root_len,
 		       struct dm_transaction_manager **tm,
-		       struct dm_space_map **sm, struct dm_block **sblock);
+		       struct dm_space_map **sm);
 
 #endif	/* _LINUX_DM_TRANSACTION_MANAGER_H */