bcachefs: Fix an assertion pop

There was a race: btree node writes drop their reference on journal pins
before clearing the btree_node_write_in_flight flag.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/btree_io.c

@@ -1829,23 +1829,6 @@ void bch2_btree_flush_all_writes(struct bch_fs *c)
 	__bch2_btree_flush_all(c, BTREE_NODE_write_in_flight);
 }
 
-void bch2_btree_verify_flushed(struct bch_fs *c)
-{
-	struct bucket_table *tbl;
-	struct rhash_head *pos;
-	struct btree *b;
-	unsigned i;
-
-	rcu_read_lock();
-	for_each_cached_btree(b, c, tbl, i, pos) {
-		unsigned long flags = READ_ONCE(b->flags);
-
-		BUG_ON((flags & (1 << BTREE_NODE_dirty)) ||
-		       (flags & (1 << BTREE_NODE_write_in_flight)));
-	}
-	rcu_read_unlock();
-}
-
 void bch2_dirty_btree_nodes_to_text(struct printbuf *out, struct bch_fs *c)
 {
 	struct bucket_table *tbl;

fs/bcachefs/btree_io.h

@@ -185,7 +185,6 @@ do {									\
 
 void bch2_btree_flush_all_reads(struct bch_fs *);
 void bch2_btree_flush_all_writes(struct bch_fs *);
-void bch2_btree_verify_flushed(struct bch_fs *);
 void bch2_dirty_btree_nodes_to_text(struct printbuf *, struct bch_fs *);
 
 static inline void compat_bformat(unsigned level, enum btree_id btree_id,

fs/bcachefs/super.c

@@ -242,10 +242,7 @@ static void __bch2_fs_read_only(struct bch_fs *c)
 	 * the journal kicks off btree writes via reclaim - wait for in flight
 	 * writes after stopping journal:
 	 */
-	if (test_bit(BCH_FS_EMERGENCY_RO, &c->flags))
-		bch2_btree_flush_all_writes(c);
-	else
-		bch2_btree_verify_flushed(c);
+	bch2_btree_flush_all_writes(c);
 
 	/*
 	 * After stopping journal: