fs: btrfs: Crossport open_ctree_fs_info() from btrfs-progs

open_ctree_fs_info() is the main entry point to open btrfs.

This version is a simplfied version of __open_ctree_fd() of btrfs-progs,
the main differences are:
- Parameters on how to specify a block device
  Instead of @fd and @path, U-Boot uses blk_desc and disk_partition_t.

- Remove open_ctree flags
  There won't be multiple open ctree modes in U-Boot.

Otherwise functions structures are all kept the same.

With open_ctree_fs_info() implemented, also introduce the global
current_fs_info pointer to show the current opened btrfs.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Marek Behún <marek.behun@nic.cz>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 7c814fd2a9..b050b5844d 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1275,6 +1275,10 @@ const char *btrfs_super_csum_name(u16 csum_type);
 u16 btrfs_csum_type_size(u16 csum_type);
 size_t btrfs_super_num_csums(void);
 
+/* root-tree.c */
+int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
+			struct btrfs_root_item *item, struct btrfs_key *key);
+
 /* ctree.c */
 int btrfs_comp_cpu_keys(const struct btrfs_key *k1, const struct btrfs_key *k2);
 enum btrfs_tree_block_status