btrfsck: add --init-csum-tree to replace the csum root with an empty one

This will effectively delete all of your crcs, but at least you'll
be able to mount the FS with nodatasum.

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

1 files changed, 40 insertions, 0 deletions

diff --git a/ctree.c b/ctree.c
index 005550f..282c868 100644
--- a/ctree.c
+++ b/ctree.c
@@ -138,6 +138,46 @@ int btrfs_copy_root(struct btrfs_trans_handle *trans,
 	return 0;
 }
 
+int btrfs_fsck_reinit_root(struct btrfs_trans_handle *trans,
+		      struct btrfs_root *root)
+{
+	struct extent_buffer *c;
+	struct extent_buffer *old = root->node;
+	int level;
+	struct btrfs_disk_key disk_key = {0,0,0};
+
+	level = 0;
+
+	c = btrfs_alloc_free_block(trans, root,
+				   btrfs_level_size(root, 0),
+				   root->root_key.objectid,
+				   &disk_key, level, 0, 0);
+	if (IS_ERR(c))
+		return PTR_ERR(c);
+
+	memset_extent_buffer(c, 0, 0, sizeof(struct btrfs_header));
+	btrfs_set_header_level(c, level);
+	btrfs_set_header_bytenr(c, c->start);
+	btrfs_set_header_generation(c, trans->transid);
+	btrfs_set_header_backref_rev(c, BTRFS_MIXED_BACKREF_REV);
+	btrfs_set_header_owner(c, root->root_key.objectid);
+
+	write_extent_buffer(c, root->fs_info->fsid,
+			    (unsigned long)btrfs_header_fsid(c),
+			    BTRFS_FSID_SIZE);
+
+	write_extent_buffer(c, root->fs_info->chunk_tree_uuid,
+			    (unsigned long)btrfs_header_chunk_tree_uuid(c),
+			    BTRFS_UUID_SIZE);
+
+	btrfs_mark_buffer_dirty(c);
+
+	free_extent_buffer(old);
+	root->node = c;
+	add_root_to_dirty_list(root);
+	return 0;
+}
+
 /*
  * check if the tree block can be shared by multiple trees
  */