1 files changed, 92 insertions, 0 deletions

diff --git a/fs/nilfs2/the_nilfs.c b/fs/nilfs2/the_nilfs.c
index 6a012b9e1b31..f1d599273d9e 100644
--- a/fs/nilfs2/the_nilfs.c
+++ b/fs/nilfs2/the_nilfs.c
@@ -89,6 +89,8 @@ static struct the_nilfs *alloc_nilfs(struct block_device *bdev)
         INIT_LIST_HEAD(&nilfs->ns_supers);
         INIT_LIST_HEAD(&nilfs->ns_gc_inodes);
         spin_lock_init(&nilfs->ns_last_segment_lock);
+        nilfs->ns_cptree = RB_ROOT;
+        spin_lock_init(&nilfs->ns_cptree_lock);
         init_rwsem(&nilfs->ns_segctor_sem);
 
         return nilfs;
@@ -809,6 +811,96 @@ int nilfs_near_disk_full(struct the_nilfs *nilfs)
         return ncleansegs <= nilfs->ns_nrsvsegs + nincsegs;
 }
 
+struct nilfs_root *nilfs_lookup_root(struct the_nilfs *nilfs, __u64 cno)
+{
+        struct rb_node *n;
+        struct nilfs_root *root;
+
+        spin_lock(&nilfs->ns_cptree_lock);
+        n = nilfs->ns_cptree.rb_node;
+        while (n) {
+                root = rb_entry(n, struct nilfs_root, rb_node);
+
+                if (cno < root->cno) {
+                        n = n->rb_left;
+                } else if (cno > root->cno) {
+                        n = n->rb_right;
+                } else {
+                        atomic_inc(&root->count);
+                        spin_unlock(&nilfs->ns_cptree_lock);
+                        return root;
+                }
+        }
+        spin_unlock(&nilfs->ns_cptree_lock);
+
+        return NULL;
+}
+
+struct nilfs_root *
+nilfs_find_or_create_root(struct the_nilfs *nilfs, __u64 cno)
+{
+        struct rb_node **p, *parent;
+        struct nilfs_root *root, *new;
+
+        root = nilfs_lookup_root(nilfs, cno);
+        if (root)
+                return root;
+
+        new = kmalloc(sizeof(*root), GFP_KERNEL);
+        if (!new)
+                return NULL;
+
+        spin_lock(&nilfs->ns_cptree_lock);
+
+        p = &nilfs->ns_cptree.rb_node;
+        parent = NULL;
+
+        while (*p) {
+                parent = *p;
+                root = rb_entry(parent, struct nilfs_root, rb_node);
+
+                if (cno < root->cno) {
+                        p = &(*p)->rb_left;
+                } else if (cno > root->cno) {
+                        p = &(*p)->rb_right;
+                } else {
+                        atomic_inc(&root->count);
+                        spin_unlock(&nilfs->ns_cptree_lock);
+                        kfree(new);
+                        return root;
+                }
+        }
+
+        new->cno = cno;
+        new->ifile = NULL;
+        new->nilfs = nilfs;
+        atomic_set(&new->count, 1);
+        atomic_set(&new->inodes_count, 0);
+        atomic_set(&new->blocks_count, 0);
+
+        rb_link_node(&new->rb_node, parent, p);
+        rb_insert_color(&new->rb_node, &nilfs->ns_cptree);
+
+        spin_unlock(&nilfs->ns_cptree_lock);
+
+        return new;
+}
+
+void nilfs_put_root(struct nilfs_root *root)
+{
+        if (atomic_dec_and_test(&root->count)) {
+                struct the_nilfs *nilfs = root->nilfs;
+
+                spin_lock(&nilfs->ns_cptree_lock);
+                rb_erase(&root->rb_node, &nilfs->ns_cptree);
+                spin_unlock(&nilfs->ns_cptree_lock);
+                if (root->ifile)
+                        nilfs_mdt_destroy(root->ifile);
+
+                kfree(root);
+        }
+}
+
 /**
  * nilfs_find_sbinfo - find existing nilfs_sb_info structure
  * @nilfs: nilfs object