ext4: fix mmap data corruption in nodelalloc mode when blocksize < pagesize

Since commit 90a8020 and d6320cb, Jan Kara has fixed this issue partially.
This mmap data corruption still exists in nodelalloc mode, fix this.

Signed-off-by: Xiaoguang Wang <[e-mail]>
Signed-off-by: Theodore Ts'o <[e-mail]>
Reviewed-by: Jan Kara <[e-mail]>

fs/ext4/inode.c

···
 {
 	handle_t *handle = ext4_journal_current_handle();
 	struct inode *inode = mapping->host;
+	loff_t old_size = inode->i_size;
 	int ret = 0, ret2;
 	int i_size_changed = 0;
 
···
 	unlock_page(page);
 	page_cache_release(page);
 
+	if (old_size < pos)
+		pagecache_isize_extended(inode, old_size, pos);
 	/*
 	 * Don't mark the inode dirty under page lock. First, it unnecessarily
 	 * makes the holding time of page lock longer. Second, it forces lock
···
 {
 	handle_t *handle = ext4_journal_current_handle();
 	struct inode *inode = mapping->host;
+	loff_t old_size = inode->i_size;
 	int ret = 0, ret2;
 	int partial = 0;
 	unsigned from, to;
···
 	EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
 	unlock_page(page);
 	page_cache_release(page);
+
+	if (old_size < pos)
+		pagecache_isize_extended(inode, old_size, pos);
 
 	if (size_changed) {
 		ret2 = ext4_mark_inode_dirty(handle, inode);