1 files changed, 11 insertions, 3 deletions

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 2b3590b9fe98..56695595e036 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -1241,12 +1241,20 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
                         schedule_timeout(1);
 
                 finish_wait(&cur_trans->writer_wait, &wait);
-                spin_lock(&root->fs_info->trans_lock);
-                root->fs_info->trans_no_join = 1;
-                spin_unlock(&root->fs_info->trans_lock);
         } while (atomic_read(&cur_trans->num_writers) > 1 ||
                  (should_grow && cur_trans->num_joined != joined));
 
+        /*
+         * Ok now we need to make sure to block out any other joins while we
+         * commit the transaction.  We could have started a join before setting
+         * no_join so make sure to wait for num_writers to == 1 again.
+         */
+        spin_lock(&root->fs_info->trans_lock);
+        root->fs_info->trans_no_join = 1;
+        spin_unlock(&root->fs_info->trans_lock);
+        wait_event(cur_trans->writer_wait,
+                   atomic_read(&cur_trans->num_writers) == 1);
+
         ret = create_pending_snapshots(trans, root->fs_info);
         BUG_ON(ret);