bcachefs: Kill bch2_btree_node_write_cond()

bch2_btree_node_write_cond() was only used in one place - this inlines
it into __btree_node_flush() and makes the cmpxchg loop actually
correct.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

fs/bcachefs/btree_io.h

@@ -158,22 +158,6 @@ static inline void btree_node_write_if_need(struct bch_fs *c, struct btree *b,
 	bch2_btree_node_write(c, b, lock_held, BTREE_WRITE_ONLY_IF_NEED);
 }
 
-#define bch2_btree_node_write_cond(_c, _b, cond)			\
-do {									\
-	unsigned long old, new, v = READ_ONCE((_b)->flags);		\
-									\
-	do {								\
-		old = new = v;						\
-									\
-		if (!(old & (1 << BTREE_NODE_dirty)) || !(cond))	\
-			break;						\
-									\
-		new |= (1 << BTREE_NODE_need_write);			\
-	} while ((v = cmpxchg(&(_b)->flags, old, new)) != old);		\
-									\
-	btree_node_write_if_need(_c, _b, SIX_LOCK_read);		\
-} while (0)
-
 void bch2_btree_flush_all_reads(struct bch_fs *);
 void bch2_btree_flush_all_writes(struct bch_fs *);
 

fs/bcachefs/btree_update_leaf.c

@@ -168,10 +168,24 @@ static int __btree_node_flush(struct journal *j, struct journal_entry_pin *pin,
 	struct bch_fs *c = container_of(j, struct bch_fs, journal);
 	struct btree_write *w = container_of(pin, struct btree_write, journal);
 	struct btree *b = container_of(w, struct btree, writes[i]);
+	unsigned long old, new, v;
+	unsigned idx = w - b->writes;
 
 	six_lock_read(&b->c.lock, NULL, NULL);
-	bch2_btree_node_write_cond(c, b,
-		(btree_current_write(b) == w && w->journal.seq == seq));
+	v = READ_ONCE(b->flags);
+
+	do {
+		old = new = v;
+
+		if (!(old & (1 << BTREE_NODE_dirty)) ||
+		    !!(old & (1 << BTREE_NODE_write_idx)) != idx ||
+		    w->journal.seq != seq)
+			break;
+
+		new |= 1 << BTREE_NODE_need_write;
+	} while ((v = cmpxchg(&b->flags, old, new)) != old);
+
+	btree_node_write_if_need(c, b, SIX_LOCK_read);
 	six_unlock_read(&b->c.lock);
 	return 0;
 }