Partition linux page cache for each VM

Hey, I need to modify pagecache such that each VM gets their own LRU list and eviction is done from that list. I need to verify whether I'm on the right path, so can anyone please verify my approach. The first step is to identify which VM is making the call to allocate a page. As VMs are stored as a file, I can identify each VM with their filename, right? For this, I'm trying to get the filename associated with an address_space object when add_to_page_cache_lru() is called in filemap.c

From address_space object, I can get inode and therefore dentry. I'm not able to figure out how to get the name of a file.

And can you please provide brief overview of what the overall approach should be? Any comments would help. Thanks. Chirag