NFS: Define and create inode-level cache objects

Define and create inode-level cache data storage objects (as managed by
nfs_inode structs).

Each inode-level object is created in a superblock-level index object and is
itself a data storage object into which pages from the inode are stored.

The inode object key is the NFS file handle for the inode.

The inode object is given coherency data to carry in the auxiliary data
permitted by the cache.  This is a sequence made up of:

 (1) i_mtime from the NFS inode.

 (2) i_ctime from the NFS inode.

 (3) i_size from the NFS inode.

 (4) change_attr from the NFSv4 attribute data.

As the cache is a persistent cache, the auxiliary data is checked when a new
NFS in-memory inode is set up that matches an already existing data storage
object in the cache.  If the coherency data is the same, the on-disk object is
retained and used; if not, it is scrapped and a new one created.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/nfs/fscache.h b/fs/nfs/fscache.h
index 22b971e..d21b590 100644
--- a/fs/nfs/fscache.h
+++ b/fs/nfs/fscache.h
@@ -62,6 +62,7 @@ struct nfs_fscache_key {
 extern struct fscache_netfs nfs_fscache_netfs;
 extern const struct fscache_cookie_def nfs_fscache_server_index_def;
 extern const struct fscache_cookie_def nfs_fscache_super_index_def;
+extern const struct fscache_cookie_def nfs_fscache_inode_object_def;
 
 extern int nfs_fscache_register(void);
 extern void nfs_fscache_unregister(void);