This adds the ability to load the block group root, as well as make sure
the various backup super block and super block updates are made
appropriately.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
---
 kernel-shared/ctree.h       |   1 +
 kernel-shared/disk-io.c     | 156 +++++++++++++++++++++++++++---------
 kernel-shared/disk-io.h     |  10 ++-
 kernel-shared/extent-tree.c |   8 +-
 kernel-shared/transaction.c |   2 +
 5 files changed, 135 insertions(+), 42 deletions(-)

diff --git a/kernel-shared/ctree.h b/kernel-shared/ctree.h
index e54e03c4..27e31e03 100644
--- a/kernel-shared/ctree.h
+++ b/kernel-shared/ctree.h

@@ -1195,6 +1195,7 @@ struct btrfs_fs_info {
 	struct btrfs_root *dev_root;
 	struct btrfs_root *quota_root;
 	struct btrfs_root *uuid_root;
+	struct btrfs_root *block_group_root;
 
 	struct rb_root global_roots_tree;
 	struct rb_root fs_root_tree;

diff --git a/kernel-shared/disk-io.c b/kernel-shared/disk-io.c
index bea42556..38741819 100644
--- a/kernel-shared/disk-io.c
+++ b/kernel-shared/disk-io.c

@@ -838,6 +838,9 @@ struct btrfs_root *btrfs_read_fs_root(struct btrfs_fs_info *fs_info,
 		root = btrfs_global_root(fs_info, location);
 		return root ? root : ERR_PTR(-ENOENT);
 	}
+	if (location->objectid == BTRFS_BLOCK_GROUP_TREE_OBJECTID)
+		return fs_info->block_group_root ? fs_info->block_group_root :
+						ERR_PTR(-ENOENT);
 
 	BUG_ON(location->objectid == BTRFS_TREE_RELOC_OBJECTID);
 

@@ -876,6 +879,7 @@ void btrfs_free_fs_info(struct btrfs_fs_info *fs_info)
 	free(fs_info->chunk_root);
 	free(fs_info->dev_root);
 	free(fs_info->uuid_root);
+	free(fs_info->block_group_root);
 	free(fs_info->super_copy);
 	free(fs_info->log_root_tree);
 	free(fs_info);

@@ -894,10 +898,12 @@ struct btrfs_fs_info *btrfs_new_fs_info(int writable, u64 sb_bytenr)
 	fs_info->dev_root = calloc(1, sizeof(struct btrfs_root));
 	fs_info->quota_root = calloc(1, sizeof(struct btrfs_root));
 	fs_info->uuid_root = calloc(1, sizeof(struct btrfs_root));
+	fs_info->block_group_root = calloc(1, sizeof(struct btrfs_root));
 	fs_info->super_copy = calloc(1, BTRFS_SUPER_INFO_SIZE);
 
 	if (!fs_info->tree_root || !fs_info->chunk_root || !fs_info->dev_root ||
-	    !fs_info->quota_root || !fs_info->uuid_root || !fs_info->super_copy)
+	    !fs_info->quota_root || !fs_info->uuid_root ||
+	    !fs_info->block_group_root || !fs_info->super_copy)
 		goto free_all;
 
 	extent_io_tree_init(&fs_info->extent_cache);

@@ -1016,7 +1022,7 @@ static int read_root_or_create_block(struct btrfs_fs_info *fs_info,
 static inline bool maybe_load_block_groups(struct btrfs_fs_info *fs_info,
 					   u64 flags)
 {
-	struct btrfs_root *root = btrfs_extent_root(fs_info, 0);
+	struct btrfs_root *root = btrfs_block_group_root(fs_info);
 
 	if (flags & OPEN_CTREE_NO_BLOCK_GROUPS)
 		return false;

@@ -1027,7 +1033,6 @@ static inline bool maybe_load_block_groups(struct btrfs_fs_info *fs_info,
 	return false;
 }
 
-
 static int load_global_roots_objectid(struct btrfs_fs_info *fs_info,
 				      struct btrfs_path *path, u64 objectid,
 				      unsigned flags, char *str)

@@ -1125,39 +1130,94 @@ out:
 	return ret;
 }
 
-int btrfs_setup_all_roots(struct btrfs_fs_info *fs_info, u64 root_tree_bytenr,
-			  unsigned flags)
+static int load_important_roots(struct btrfs_fs_info *fs_info,
+				u64 root_tree_bytenr, unsigned flags)
 {
 	struct btrfs_super_block *sb = fs_info->super_copy;
+	struct btrfs_root_backup *backup = NULL;
 	struct btrfs_root *root;
-	struct btrfs_key key;
-	u64 generation;
+	u64 bytenr, gen;
+	int index = -1;
 	int ret;
 
-	root = fs_info->tree_root;
-	btrfs_setup_root(root, fs_info, BTRFS_ROOT_TREE_OBJECTID);
-	generation = btrfs_super_generation(sb);