[PATCH 06/12] inode: Make unused inode LRU per superblock

[Al Viro]

On Thu, Jun 02, 2011 at 05:01:01PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner at redhat.com>
> 
> The inode unused list is currently a global LRU. This does not match
> the other global filesystem cache - the dentry cache - which uses
> per-superblock LRU lists. Hence we have related filesystem object
> types using different LRU reclaimation schemes.
> 
> To enable a per-superblock filesystem cache shrinker, both of these
> caches need to have per-sb unused object LRU lists. Hence this patch
> converts the global inode LRU to per-sb LRUs.
> 
> The patch only does rudimentary per-sb propotioning in the shrinker
> infrastructure, as this gets removed when the per-sb shrinker
> callouts are introduced later on.

What protects s_nr_inodes_unused?