Btrfs-progs: allow --init-extent-tree to work when extent tree is borked

Unfortunately you can't run --init-extent-tree if you can't actually read the
extent root.  Fix this by allowing partial starts with no extent root and then
have fsck only check to see if the extent root is uptodate _after_ the check to
see if we are init'ing the extent tree.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 11 insertions, 1 deletions

diff --git a/disk-io.c b/disk-io.c
index 0af38985..7ad2cc27 100644
--- a/disk-io.c
+++ b/disk-io.c
@@ -877,7 +877,17 @@ int btrfs_setup_all_roots(struct btrfs_fs_info *fs_info, u64 root_tree_bytenr,
 				  fs_info->extent_root);
 	if (ret) {
 		printk("Couldn't setup extent tree\n");
-		return -EIO;
+		if (!(flags & OPEN_CTREE_PARTIAL))
+			return -EIO;
+		/* Need a blank node here just so we don't screw up in the
+		 * million of places that assume a root has a valid ->node
+		 */
+		fs_info->extent_root->node =
+			btrfs_find_create_tree_block(fs_info->extent_root, 0,
+						     leafsize);
+		if (!fs_info->extent_root->node)
+			return -ENOMEM;
+		clear_extent_buffer_uptodate(NULL, fs_info->extent_root->node);
 	}
 	fs_info->extent_root->track_dirty = 1;