tree a72b1f072b973723ea1cf7def27608717cf1c033
parent c732eb16bf07f9bfb7fa72b6868462471273bdbd
author Tao Ma <tao.ma@oracle.com> 1251083617 +0800
committer Joel Becker <joel.becker@oracle.com> 1253675369 -0700

ocfs2: Add refcount tree lock mechanism.

Implement locking around struct ocfs2_refcount_tree.  This protects
all read/write operations on refcount trees.  ocfs2_refcount_tree
has its own lock and its own caching_info, protecting buffers among
multiple nodes.

User must call ocfs2_lock_refcount_tree before his operation on
the tree and unlock it after that.

ocfs2_refcount_trees are referenced by the block number of the
refcount tree root block, So we create an rb-tree on the ocfs2_super
to look them up.

Signed-off-by: Tao Ma <tao.ma@oracle.com>