NFS: Remove redundant open context from nfs_page

The lock context already references and tracks the open context, so
take the opportunity to save some space in struct nfs_page.
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/pagelist.c

@@ -325,7 +325,6 @@ __nfs_create_request(struct nfs_lock_context *l_ctx, struct page *page,
 	req->wb_offset  = offset;
 	req->wb_pgbase	= pgbase;
 	req->wb_bytes   = count;
-	req->wb_context = get_nfs_open_context(ctx);
 	kref_init(&req->wb_kref);
 	req->wb_nio = 0;
 	return req;
@@ -414,8 +413,8 @@ void nfs_unlock_and_release_request(struct nfs_page *req)
 static void nfs_clear_request(struct nfs_page *req)
 {
 	struct page *page = req->wb_page;
-	struct nfs_open_context *ctx = req->wb_context;
 	struct nfs_lock_context *l_ctx = req->wb_lock_context;
+	struct nfs_open_context *ctx;
 
 	if (page != NULL) {
 		put_page(page);
@@ -424,16 +423,13 @@ static void nfs_clear_request(struct nfs_page *req)
 	if (l_ctx != NULL) {
 		if (atomic_dec_and_test(&l_ctx->io_count)) {
 			wake_up_var(&l_ctx->io_count);
+			ctx = l_ctx->open_context;
 			if (test_bit(NFS_CONTEXT_UNLOCK, &ctx->flags))
 				rpc_wake_up(&NFS_SERVER(d_inode(ctx->dentry))->uoc_rpcwaitq);
 		}
 		nfs_put_lock_context(l_ctx);
 		req->wb_lock_context = NULL;
 	}
-	if (ctx != NULL) {
-		put_nfs_open_context(ctx);
-		req->wb_context = NULL;
-	}
 }
 
 /**

include/linux/nfs_page.h

@@ -42,7 +42,6 @@ struct nfs_inode;
 struct nfs_page {
 	struct list_head	wb_list;	/* Defines state of page: */
 	struct page		*wb_page;	/* page to read in/write out */
-	struct nfs_open_context	*wb_context;	/* File state context info */
 	struct nfs_lock_context	*wb_lock_context;	/* lock context info */
 	pgoff_t			wb_index;	/* Offset >> PAGE_SHIFT */
 	unsigned int		wb_offset,	/* Offset & ~PAGE_MASK */
@@ -203,7 +202,7 @@ loff_t req_offset(struct nfs_page *req)
 static inline struct nfs_open_context *
 nfs_req_openctx(struct nfs_page *req)
 {
-	return req->wb_context;
+	return req->wb_lock_context->open_context;
 }
 
 #endif /* _LINUX_NFS_PAGE_H */