fscache: Pass object size in rather than calling back for it

Pass the object size in to fscache_acquire_cookie() and
fscache_write_page() rather than the netfs providing a callback by which it
can be received.  This makes it easier to update the size of the object
when a new page is written that extends the object.

The current object size is also passed by fscache to the check_aux
function, obviating the need to store it in the aux data.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Anna Schumaker <anna.schumaker@netapp.com>
Tested-by: Steve Dickson <steved@redhat.com>

fs/afs/inode.c

@@ -265,7 +265,7 @@ static void afs_get_inode_cache(struct afs_vnode *vnode)
 					      &afs_vnode_cache_index_def,
 					      &key, sizeof(key),
 					      &aux, sizeof(aux),
-					      vnode, true);
+					      vnode, vnode->status.size, true);
 #endif
 }