Btrfs: Fix super block updates during transaction commit

The super block written during commit was not consistent with the state of
the trees.  This change adds an in-memory copy of the super so that we can
make sure to write out consistent data during a commit.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index a5a63d471e43..3b2face593e9 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -380,6 +380,12 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
                 else
                         prev_trans->use_count++;
         }
+        btrfs_set_super_generation(&root->fs_info->super_copy,
+                                   cur_trans->transid);
+        btrfs_set_super_root(&root->fs_info->super_copy,
+                             bh_blocknr(root->fs_info->tree_root->node));
+        memcpy(root->fs_info->disk_super, &root->fs_info->super_copy,
+               sizeof(root->fs_info->super_copy));
         mutex_unlock(&root->fs_info->trans_mutex);
         mutex_unlock(&root->fs_info->fs_mutex);
         ret = btrfs_write_and_wait_transaction(trans, root);
@@ -389,8 +395,6 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
                 put_transaction(prev_trans);
                 mutex_unlock(&root->fs_info->trans_mutex);
         }
-        btrfs_set_super_generation(root->fs_info->disk_super,
-                                   cur_trans->transid);
         BUG_ON(ret);
         write_ctree_super(trans, root);