get btrfs filesystem id from kernel module

I was wondering regarding to fetching the correct fsid on btrfs.
fsid returned from stats give: 36h/54d
and fsid returned from kernel code is 52.
On kernel 11.3 3.0.101-0.47.71-default in order to get it, I do the
following: convert inode struct to btrfs_inode struct (use btrfsInode
= BTRFS_I(inode)), then from btrfs_inode struct i go to root field,
and from root i take anon_dev or anon_super.s_dev.
struct btrfs_inode *btrfsInode;
btrfsInode = BTRFS_I(inode);
btrfsInode->root->anon_super.s_dev or
btrfsInode->root->anon_dev - depend on kernel.

But in kernel 3.12.28-4-default in order to get the fsid, i need to go
to the inode -> superblock -> device id (inode->i_sb->s_dev)

And is there a proper way to get it ?

Thanks to btrfs mailing list,
the proper way to get fsid is via: BTRFS_I(inode)->root->fs_info->fsid