NFS: Add a count of the number of unstable writes carried by an inode

In order to know when we should do opportunistic commits of the unstable
writes, when the VM is doing a background flush, we add a field to count
the number of unstable writes.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/inode.c

@@ -1404,6 +1404,7 @@ static void init_once(void *foo)
 	INIT_LIST_HEAD(&nfsi->access_cache_inode_lru);
 	INIT_RADIX_TREE(&nfsi->nfs_page_tree, GFP_ATOMIC);
 	nfsi->npages = 0;
+	nfsi->ncommit = 0;
 	atomic_set(&nfsi->silly_count, 1);
 	INIT_HLIST_HEAD(&nfsi->silly_list);
 	init_waitqueue_head(&nfsi->waitqueue);