bcachefs: Fix early startup error path

Don't set JOURNAL_running until we're also calling
journal_space_available() for the first time.

If JOURNAL_running is set, shutdown will write an empty journal entry -
but this will hit an assert in journal_entry_open() if we've never
called journal_space_available().

Reported-by: syzbot+53bb24d476ef8368a7f0@syzkaller.appspotmail.com
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

1 files changed, 9 insertions, 10 deletions

diff --git a/fs/bcachefs/super.c b/fs/bcachefs/super.c
index e8a17ed1615d..a8bc02540cce 100644
--- a/fs/bcachefs/super.c
+++ b/fs/bcachefs/super.c
@@ -466,29 +466,28 @@ static int __bch2_fs_read_write(struct bch_fs *c, bool early)
 
 	clear_bit(BCH_FS_clean_shutdown, &c->flags);
 
+	__for_each_online_member(c, ca, BIT(BCH_MEMBER_STATE_rw), READ) {
+		bch2_dev_allocator_add(c, ca);
+		percpu_ref_reinit(&ca->io_ref[WRITE]);
+	}
+	bch2_recalc_capacity(c);
+
 	/*
 	 * First journal write must be a flush write: after a clean shutdown we
 	 * don't read the journal, so the first journal write may end up
 	 * overwriting whatever was there previously, and there must always be
 	 * at least one non-flush write in the journal or recovery will fail:
 	 */
+	spin_lock(&c->journal.lock);
 	set_bit(JOURNAL_need_flush_write, &c->journal.flags);
 	set_bit(JOURNAL_running, &c->journal.flags);
-
-	__for_each_online_member(c, ca, BIT(BCH_MEMBER_STATE_rw), READ) {
-		bch2_dev_allocator_add(c, ca);
-		percpu_ref_reinit(&ca->io_ref[WRITE]);
-	}
-	bch2_recalc_capacity(c);
+	bch2_journal_space_available(&c->journal);
+	spin_unlock(&c->journal.lock);
 
 	ret = bch2_fs_mark_dirty(c);
 	if (ret)
 		goto err;
 
-	spin_lock(&c->journal.lock);
-	bch2_journal_space_available(&c->journal);
-	spin_unlock(&c->journal.lock);
-
 	ret = bch2_journal_reclaim_start(&c->journal);
 	if (ret)
 		goto err;