dm thin metadata: remove needless work from __commit_transaction

Commit 5a32083d ("dm: take care to copy the space map roots before
locking the superblock") properly removed the calls to dm_sm_root_size()
from __write_initial_superblock().  But the dm_sm_root_size() calls were
left dangling in __commit_transaction().

Fixes: 5a32083d ("dm: take care to copy the space map roots before locking the superblock")
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

drivers/md/dm-thin-metadata.c

@@ -776,7 +776,6 @@ static int __write_changed_details(struct dm_pool_metadata *pmd)
 static int __commit_transaction(struct dm_pool_metadata *pmd)
 {
 	int r;
-	size_t metadata_len, data_len;
 	struct thin_disk_superblock *disk_super;
 	struct dm_block *sblock;
 
@@ -797,14 +796,6 @@ static int __commit_transaction(struct dm_pool_metadata *pmd)
 	if (r < 0)
 		return r;
 
-	r = dm_sm_root_size(pmd->metadata_sm, &metadata_len);
-	if (r < 0)
-		return r;
-
-	r = dm_sm_root_size(pmd->data_sm, &data_len);
-	if (r < 0)
-		return r;
-
 	r = save_sm_roots(pmd);
 	if (r < 0)
 		return r;