[PATCH] splice: partial write fix

Currently if partial write has happened while ->commit_write() then page
wasn't marked as accessed and rebalanced.
Signed-off-by: Monakhov Dmitriy <dmonakhov@openvz.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

fs/splice.c

@@ -627,18 +627,25 @@ static int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
 	}
 
 	ret = mapping->a_ops->commit_write(file, page, offset, offset+this_len);
-	if (!ret) {
+	if (ret) {
+		if (ret == AOP_TRUNCATED_PAGE) {
+			page_cache_release(page);
+			goto find_page;
+		}
+		if (ret < 0)
+			goto out;
+		/*
+		 * Partial write has happened, so 'ret' already initialized by
+		 * number of bytes written, Where is nothing we have to do here.
+		 */
+	} else
+		ret = this_len;
 	/*
 	 * Return the number of bytes written and mark page as
 	 * accessed, we are now done!
 	 */
-		ret = this_len;
 	mark_page_accessed(page);
 	balance_dirty_pages_ratelimited(mapping);
-	} else if (ret == AOP_TRUNCATED_PAGE) {
-		page_cache_release(page);
-		goto find_page;
-	}
 out:
 	page_cache_release(page);
 	unlock_page(page);