new helper: ihold()

Clones an existing reference to inode; caller must already hold one.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c
index e4b75d6..9c8e87b 100644
--- a/fs/anon_inodes.c
+++ b/fs/anon_inodes.c
@@ -111,10 +111,9 @@
 	path.mnt = mntget(anon_inode_mnt);
 	/*
 	 * We know the anon_inode inode count is always greater than zero,
-	 * so we can avoid doing an igrab() and we can use an open-coded
-	 * atomic_inc().
+	 * so ihold() is safe.
 	 */
-	atomic_inc(&anon_inode_inode->i_count);
+	ihold(anon_inode_inode);
 
 	path.dentry->d_op = &anon_inodefs_dentry_operations;
 	d_instantiate(path.dentry, anon_inode_inode);