NFS: Convert struct nfs_page to use krefs

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index f8a4ba5..257a7f8 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -85,9 +85,8 @@
 	req->wb_offset  = offset;
 	req->wb_pgbase	= offset;
 	req->wb_bytes   = count;
-	atomic_set(&req->wb_count, 1);
 	req->wb_context = get_nfs_open_context(ctx);
-
+	kref_init(&req->wb_kref);
 	return req;
 }
 
@@ -160,11 +159,9 @@
  *
  * Note: Should never be called with the spinlock held!
  */
-void
-nfs_release_request(struct nfs_page *req)
+static void nfs_free_request(struct kref *kref)
 {
-	if (!atomic_dec_and_test(&req->wb_count))
-		return;
+	struct nfs_page *req = container_of(kref, struct nfs_page, wb_kref);
 
 	/* Release struct file or cached credential */
 	nfs_clear_request(req);
@@ -172,6 +169,11 @@
 	nfs_page_free(req);
 }
 
+void nfs_release_request(struct nfs_page *req)
+{
+	kref_put(&req->wb_kref, nfs_free_request);
+}
+
 static int nfs_wait_bit_interruptible(void *word)
 {
 	int ret = 0;
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 9e7c21d..e940432 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -117,7 +117,7 @@
 	if (PagePrivate(page)) {
 		req = (struct nfs_page *)page_private(page);
 		if (req != NULL)
-			atomic_inc(&req->wb_count);
+			kref_get(&req->wb_kref);
 	}
 	return req;
 }
@@ -398,7 +398,7 @@
 	if (PageDirty(req->wb_page))
 		set_bit(PG_NEED_FLUSH, &req->wb_flags);
 	nfsi->npages++;
-	atomic_inc(&req->wb_count);
+	kref_get(&req->wb_kref);
 	return 0;
 }
 
@@ -531,7 +531,7 @@
 		next = req->wb_index + 1;
 		BUG_ON(!NFS_WBACK_BUSY(req));
 
-		atomic_inc(&req->wb_count);
+		kref_get(&req->wb_kref);
 		spin_unlock(&nfsi->req_lock);
 		error = nfs_wait_on_request(req);
 		nfs_release_request(req);