1 files changed, 32 insertions, 0 deletions

diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index 39e7d7f8eda0..ab96d26bf7e9 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -833,6 +833,38 @@ static int nilfs_try_to_shrink_tree(struct dentry *root_dentry)
         return nilfs_tree_was_touched(root_dentry);
 }
 
+int nilfs_checkpoint_is_mounted(struct super_block *sb, __u64 cno)
+{
+        struct the_nilfs *nilfs = NILFS_SB(sb)->s_nilfs;
+        struct nilfs_root *root;
+        struct inode *inode;
+        struct dentry *dentry;
+        int ret;
+
+        if (cno < 0 || cno > nilfs->ns_cno)
+                return false;
+
+        if (cno >= nilfs_last_cno(nilfs))
+                return true;    /* protect recent checkpoints */
+
+        ret = false;
+        root = nilfs_lookup_root(NILFS_SB(sb)->s_nilfs, cno);
+        if (root) {
+                inode = nilfs_ilookup(sb, root, NILFS_ROOT_INO);
+                if (inode) {
+                        dentry = d_find_alias(inode);
+                        if (dentry) {
+                                if (nilfs_tree_was_touched(dentry))
+                                        ret = nilfs_try_to_shrink_tree(dentry);
+                                dput(dentry);
+                        }
+                        iput(inode);
+                }
+                nilfs_put_root(root);
+        }
+        return ret;
+}
+
 /**
  * nilfs_fill_super() - initialize a super block instance
  * @sb: super_block