iunique -- get a unique inode number
(struct super_block * sb, ino_t max_reserved);
highest reserved inode number
Obtain an inode number that is unique on the system for a given
superblock. This is used by file systems that have no natural
permanent inode numbering system. An inode number is returned that
is higher than the reserved limit but unique.
With a large number of inodes live on the file system this function
currently becomes quite slow.