fuse: fix SetPageUptodate() condition in STORE

As noticed by Coverity the "num != 0" condition never triggers.  Instead it
should check for a complete page.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

fs/fuse/dev.c

@@ -1587,7 +1587,8 @@ static int fuse_notify_store(struct fuse_conn *fc, unsigned int size,
 
 		this_num = min_t(unsigned, num, PAGE_CACHE_SIZE - offset);
 		err = fuse_copy_page(cs, &page, offset, this_num, 0);
-		if (!err && offset == 0 && (num != 0 || file_size == end))
+		if (!err && offset == 0 &&
+		    (this_num == PAGE_CACHE_SIZE || file_size == end))
 			SetPageUptodate(page);
 		unlock_page(page);
 		page_cache_release(page);