bcachefs: Add a mechanism for blocking the journal

3 files changed, 47 insertions, 3 deletions

diff --git a/fs/bcachefs/journal.c b/fs/bcachefs/journal.c
index 8ff8cfa8bf76..0acfbfe0ef77 100644
--- a/fs/bcachefs/journal.c
+++ b/fs/bcachefs/journal.c
@@ -212,6 +212,9 @@ static int journal_entry_open(struct journal *j)
 	lockdep_assert_held(&j->lock);
 	BUG_ON(journal_entry_is_open(j));
 
+	if (j->blocked)
+		return -EAGAIN;
+
 	if (!fifo_free(&j->pin))
 		return 0;
 
@@ -286,7 +289,7 @@ static bool __journal_entry_close(struct journal *j)
 	default:
 		spin_unlock(&j->lock);
 	case JOURNAL_UNLOCKED:
-		return true;
+		return false;
 	}
 }
 
@@ -296,6 +299,22 @@ static bool journal_entry_close(struct journal *j)
 	return __journal_entry_close(j);
 }
 
+static bool journal_quiesced(struct journal *j)
+{
+	bool ret;
+
+	spin_lock(&j->lock);
+	ret = !j->reservations.prev_buf_unwritten &&
+		!journal_entry_is_open(j);
+	__journal_entry_close(j);
+	return ret;
+}
+
+static void journal_quiesce(struct journal *j)
+{
+	wait_event(j->wait, journal_quiesced(j));
+}
+
 static void journal_write_work(struct work_struct *work)
 {
 	struct journal *j = container_of(work, struct journal, write_work.work);
@@ -721,6 +740,26 @@ int bch2_journal_flush(struct journal *j)
 	return bch2_journal_flush_seq(j, seq);
 }
 
+/* block/unlock the journal: */
+
+void bch2_journal_unblock(struct journal *j)
+{
+	spin_lock(&j->lock);
+	j->blocked--;
+	spin_unlock(&j->lock);
+
+	journal_wake(j);
+}
+
+void bch2_journal_block(struct journal *j)
+{
+	spin_lock(&j->lock);
+	j->blocked++;
+	spin_unlock(&j->lock);
+
+	journal_quiesce(j);
+}
+
 /* allocate journal on a device: */
 
 static int __bch2_set_nr_journal_buckets(struct bch_dev *ca, unsigned nr,
@@ -930,8 +969,7 @@ void bch2_fs_journal_stop(struct journal *j)
 	    c->btree_roots_dirty)
 		bch2_journal_meta(j);
 
-	BUG_ON(journal_entry_is_open(j) ||
-	       j->reservations.prev_buf_unwritten);
+	journal_quiesce(j);
 
 	BUG_ON(!bch2_journal_error(j) &&
 	       test_bit(JOURNAL_NOT_EMPTY, &j->flags));
diff --git a/fs/bcachefs/journal.h b/fs/bcachefs/journal.h
index 50d864a3cae3..9c395fd041f0 100644
--- a/fs/bcachefs/journal.h
+++ b/fs/bcachefs/journal.h
@@ -367,6 +367,9 @@ static inline void bch2_journal_set_replay_done(struct journal *j)
 	set_bit(JOURNAL_REPLAY_DONE, &j->flags);
 }
 
+void bch2_journal_unblock(struct journal *);
+void bch2_journal_block(struct journal *);
+
 ssize_t bch2_journal_print_debug(struct journal *, char *);
 ssize_t bch2_journal_print_pins(struct journal *, char *);
 
diff --git a/fs/bcachefs/journal_types.h b/fs/bcachefs/journal_types.h
index a91662f6a61b..bbf1aa727a30 100644
--- a/fs/bcachefs/journal_types.h
+++ b/fs/bcachefs/journal_types.h
@@ -141,6 +141,9 @@ struct journal {
 
 	spinlock_t		lock;
 
+	/* if nonzero, we may not open a new journal entry: */
+	unsigned		blocked;
+
 	/* Used when waiting because the journal was full */
 	wait_queue_head_t	wait;
 	struct closure_waitlist	async_wait;