bcachefs: Call bch2_btree_update_add_new_node() before dropping write lock

btree nodes can be written by other threads (shrinker, journal reclaim)
with only a read lock, but brand new nodes should only be written by the
thread doing the split/interior update. bch2_btree_update_add_new_node()
sets btree node flags to indicate that this is a new node and should not
be written out by other threads, thus we need to call it before dropping
our write lock.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

diff --git a/fs/bcachefs/btree_update_interior.c b/fs/bcachefs/btree_update_interior.c
index 84a1cd0a0a4fb808b25573ad61ff58a3412126aa..9680d83f90366c5b06b3ffe6554925d125238851 100644 (file)
--- a/fs/bcachefs/btree_update_interior.c
+++ b/fs/bcachefs/btree_update_interior.c
@@ -429,7 +429,6 @@ static struct btree *__btree_root_alloc(struct btree_update *as,
 
        btree_node_set_format(b, b->data->format);
        bch2_btree_build_aux_trees(b);
-       six_unlock_write(&b->c.lock);
 
        return b;
 }
@@ -1528,6 +1527,9 @@ static int btree_split(struct btree_update *as, struct btree_trans *trans,
 
                bch2_btree_build_aux_trees(n2);
                bch2_btree_build_aux_trees(n1);
+
+               bch2_btree_update_add_new_node(as, n1);
+               bch2_btree_update_add_new_node(as, n2);
                six_unlock_write(&n2->c.lock);
                six_unlock_write(&n1->c.lock);
 
@@ -1541,9 +1543,6 @@ static int btree_split(struct btree_update *as, struct btree_trans *trans,
                mark_btree_node_locked(trans, path2, n2->c.level, SIX_LOCK_intent);
                bch2_btree_path_level_init(trans, path2, n2);
 
-               bch2_btree_update_add_new_node(as, n1);
-               bch2_btree_update_add_new_node(as, n2);
-
                /*
                 * Note that on recursive parent_keys == keys, so we
                 * can't start adding new keys to parent_keys before emptying it
@@ -1556,6 +1555,9 @@ static int btree_split(struct btree_update *as, struct btree_trans *trans,
                        /* Depth increases, make a new root */
                        n3 = __btree_root_alloc(as, trans, b->c.level + 1);
 
+                       bch2_btree_update_add_new_node(as, n3);
+                       six_unlock_write(&n3->c.lock);
+
                        path2->locks_want++;
                        BUG_ON(btree_node_locked(path2, n3->c.level));
                        six_lock_increment(&n3->c.lock, SIX_LOCK_intent);
@@ -1565,14 +1567,13 @@ static int btree_split(struct btree_update *as, struct btree_trans *trans,
                        n3->sib_u64s[0] = U16_MAX;
                        n3->sib_u64s[1] = U16_MAX;
 
-                       bch2_btree_update_add_new_node(as, n3);
-
                        btree_split_insert_keys(as, trans, path, n3, &as->parent_keys);
                }
        } else {
                trace_and_count(c, btree_node_compact, c, b);
 
                bch2_btree_build_aux_trees(n1);
+               bch2_btree_update_add_new_node(as, n1);
                six_unlock_write(&n1->c.lock);
 
                path1 = get_unlocked_mut_path(trans, path->btree_id, n1->c.level, n1->key.k.p);
@@ -1580,8 +1581,6 @@ static int btree_split(struct btree_update *as, struct btree_trans *trans,
                mark_btree_node_locked(trans, path1, n1->c.level, SIX_LOCK_intent);
                bch2_btree_path_level_init(trans, path1, n1);
 
-               bch2_btree_update_add_new_node(as, n1);
-
                if (parent)
                        bch2_keylist_add(&as->parent_keys, &n1->key);
        }
@@ -1904,9 +1903,8 @@ int __bch2_foreground_maybe_merge(struct btree_trans *trans,
        bch2_btree_sort_into(c, n, next);
 
        bch2_btree_build_aux_trees(n);
-       six_unlock_write(&n->c.lock);
-
        bch2_btree_update_add_new_node(as, n);
+       six_unlock_write(&n->c.lock);
 
        new_path = get_unlocked_mut_path(trans, path->btree_id, n->c.level, n->key.k.p);
        six_lock_increment(&n->c.lock, SIX_LOCK_intent);
@@ -1980,9 +1978,9 @@ int bch2_btree_node_rewrite(struct btree_trans *trans,
        bch2_btree_interior_update_will_free_node(as, b);
 
        n = bch2_btree_node_alloc_replacement(as, trans, b);
-       bch2_btree_update_add_new_node(as, n);
 
        bch2_btree_build_aux_trees(n);
+       bch2_btree_update_add_new_node(as, n);
        six_unlock_write(&n->c.lock);
 
        new_path = get_unlocked_mut_path(trans, iter->btree_id, n->c.level, n->key.k.p);