fs/9p: [fscache] wait for page write in cached mode

We need to call fscache_wait_on_page_write in launder_page
for fscache

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

fs/9p/cache.c

@@ -461,3 +461,14 @@ void __v9fs_readpage_to_fscache(struct inode *inode, struct page *page)
 	if (ret != 0)
 		v9fs_uncache_page(inode, page);
 }
+
+/*
+ * wait for a page to complete writing to the cache
+ */
+void __v9fs_fscache_wait_on_page_write(struct inode *inode, struct page *page)
+{
+	const struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
+	P9_DPRINTK(P9_DEBUG_FSC, "inode %p page %p", inode, page);
+	if (PageFsCache(page))
+		fscache_wait_on_page_write(vcookie->fscache, page);
+}

fs/9p/cache.h

@@ -64,8 +64,8 @@ extern int __v9fs_readpages_from_fscache(struct inode *inode,
 					 struct list_head *pages,
 					 unsigned *nr_pages);
 extern void __v9fs_readpage_to_fscache(struct inode *inode, struct page *page);
-
-
+extern void __v9fs_fscache_wait_on_page_write(struct inode *inode,
+					      struct page *page);
 /**
  * v9fs_cache_register - Register v9fs file system with the cache
  */
@@ -131,6 +131,12 @@ static inline void v9fs_vcookie_set_qid(struct inode *inode,
 	spin_unlock(&vcookie->lock);
 }
 
+static inline void v9fs_fscache_wait_on_page_write(struct inode *inode,
+						   struct page *page)
+{
+	return __v9fs_fscache_wait_on_page_write(inode, page);
+}
+
 #else /* CONFIG_9P_FSCACHE */
 
 static inline int v9fs_cache_register(void)
@@ -172,5 +178,11 @@ static inline void v9fs_vcookie_set_qid(struct inode *inode,
 					struct p9_qid *qid)
 {}
 
+static inline void v9fs_fscache_wait_on_page_write(struct inode *inode,
+						   struct page *page)
+{
+	return;
+}
+
 #endif /* CONFIG_9P_FSCACHE */
 #endif /* _9P_CACHE_H */

fs/9p/vfs_addr.c

@@ -151,6 +151,8 @@ static void v9fs_invalidate_page(struct page *page, unsigned long offset)
 
 static int v9fs_launder_page(struct page *page)
 {
+	struct inode *inode = page->mapping->host;
+	v9fs_fscache_wait_on_page_write(inode, page);
 	return 0;
 }