Btrfs: add missing extent state caching calls

When we didn't find a matching extent state, we inserted a new one
but didn't cache it in the **cached_state parameter, which makes a
subsequent call do a tree lookup to get it.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>

fs/btrfs/extent_io.c

@@ -817,6 +817,7 @@ __set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 		if (err)
 			extent_io_tree_panic(tree, err);
 
+		cache_state(prealloc, cached_state);
 		prealloc = NULL;
 		goto out;
 	}
@@ -1040,9 +1041,10 @@ int convert_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 			goto out;
 		}
 		err = insert_state(tree, prealloc, start, end, &bits);
-		prealloc = NULL;
 		if (err)
 			extent_io_tree_panic(tree, err);
+		cache_state(prealloc, cached_state);
+		prealloc = NULL;
 		goto out;
 	}
 	state = rb_entry(node, struct extent_state, rb_node);