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, 2 insertions, 3 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index d7615e1578c..7081729d5b1 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -471,6 +471,8 @@ struct btrfs_root *open_ctree(struct super_block *sb)
         if (!fs_info->sb_buffer)
                 goto fail_iput;
         disk_super = (struct btrfs_super_block *)fs_info->sb_buffer->b_data;
+        fs_info->disk_super = disk_super;
+        memcpy(&fs_info->super_copy, disk_super, sizeof(fs_info->super_copy));
 
         if (!btrfs_super_root(disk_super))
                 goto fail_sb_buffer;
@@ -479,7 +481,6 @@ struct btrfs_root *open_ctree(struct super_block *sb)
                      btrfs_super_total_blocks(disk_super) <<
                      fs_info->btree_inode->i_blkbits);
 
-        fs_info->disk_super = disk_super;
 
         if (strncmp((char *)(&disk_super->magic), BTRFS_MAGIC,
                     sizeof(disk_super->magic))) {
@@ -527,8 +528,6 @@ int write_ctree_super(struct btrfs_trans_handle *trans, struct btrfs_root
         int ret;
         struct buffer_head *bh = root->fs_info->sb_buffer;
 
-        btrfs_set_super_root(root->fs_info->disk_super,
-                             bh_blocknr(root->fs_info->tree_root->node));
         lock_buffer(bh);
         WARN_ON(atomic_read(&bh->b_count) < 1);
         clear_buffer_dirty(bh);