bcachefs: Fix a shutdown bug

btree node prefetching can kick off reads in the background - have to
flush them

3 files changed, 40 insertions, 0 deletions

diff --git a/fs/bcachefs/btree_io.c b/fs/bcachefs/btree_io.c
index f4acfcdc3f21..9b4eff1c83d1 100644
--- a/fs/bcachefs/btree_io.c
+++ b/fs/bcachefs/btree_io.c
@@ -1918,6 +1918,34 @@ void bch2_btree_node_write(struct bch_fs *c, struct btree *b,
 	}
 }
 
+static void __bch2_btree_flush_all(struct bch_fs *c, unsigned flag)
+{
+	struct bucket_table *tbl;
+	struct rhash_head *pos;
+	struct btree *b;
+	unsigned i;
+restart:
+	rcu_read_lock();
+	for_each_cached_btree(b, c, tbl, i, pos)
+		if (test_bit(flag, &b->flags)) {
+			rcu_read_unlock();
+			wait_on_bit_io(&b->flags, flag, TASK_UNINTERRUPTIBLE);
+			goto restart;
+
+		}
+	rcu_read_unlock();
+}
+
+void bch2_btree_flush_all_reads(struct bch_fs *c)
+{
+	__bch2_btree_flush_all(c, BTREE_NODE_read_in_flight);
+}
+
+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;
diff --git a/fs/bcachefs/btree_io.h b/fs/bcachefs/btree_io.h
index c0b5a0b637e1..f27907168629 100644
--- a/fs/bcachefs/btree_io.h
+++ b/fs/bcachefs/btree_io.h
@@ -136,6 +136,8 @@ do {									\
 	}								\
 } while (0)
 
+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 *);
 ssize_t bch2_dirty_btree_nodes_print(struct bch_fs *, char *);
 
diff --git a/fs/bcachefs/super.c b/fs/bcachefs/super.c
index 4c8569b02e1f..8c7a147a0833 100644
--- a/fs/bcachefs/super.c
+++ b/fs/bcachefs/super.c
@@ -259,6 +259,13 @@ static void __bch2_fs_read_only(struct bch_fs *c)
 	bch2_fs_journal_stop(&c->journal);
 
 	/*
+	 * 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);
+
+	/*
 	 * After stopping journal:
 	 */
 	for_each_member_device(ca, c, i)
@@ -476,6 +483,9 @@ void bch2_fs_stop(struct bch_fs *c)
 
 	bch_fs_mark_clean(c);
 
+	/* btree prefetch might have kicked off reads in the background: */
+	bch2_btree_flush_all_reads(c);
+
 	for_each_member_device(ca, c, i)
 		cancel_work_sync(&ca->io_error_work);