inode: Make unused inode LRU per superblock

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.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index a0011aef4338..9724f0a48742 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1397,6 +1397,10 @@ struct super_block {
         struct list_head        s_dentry_lru;   /* unused dentry lru */
         int                     s_nr_dentry_unused;     /* # of dentry on lru */
 
+        /* inode_lru_lock protects s_inode_lru and s_nr_inodes_unused */
+        struct list_head        s_inode_lru;            /* unused inode lru */
+        int                     s_nr_inodes_unused;     /* # of inodes on lru */
+
         struct block_device     *s_bdev;
         struct backing_dev_info *s_bdi;
         struct mtd_info         *s_mtd;