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>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index 6688d19e4451..bb5357376ef5 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -408,6 +408,10 @@ struct ocfs2_super
 
         /* the group we used to allocate inodes. */
         u64                             osb_inode_alloc_group;
+
+        /* rb tree root for refcount lock. */
+        struct rb_root  osb_rf_lock_tree;
+        struct ocfs2_refcount_tree *osb_ref_tree_lru;
 };
 
 #define OCFS2_SB(sb)        ((struct ocfs2_super *)(sb)->s_fs_info)