[PATCH, RFC] xfs: add heuristic to flush on rename

[Christoph Hellwig]

> +	/*
> +	 * If we are renaming a just-written file over an existing
> +	 * file, be pedantic and flush it out if it looks like somebody
> +	 * is doing a tmpfile dance, and didn't fsync.  Best effort;
> +	 * ignore errors.
> +	 */
> +	if (new_inode) {
> +		xfs_inode_t *ip = XFS_I(odentry->d_inode);
> +
> +		if (VN_DIRTY(VFS_I(ip)) && ip->i_delayed_blks > 0)
> +			filemap_flush(new_inode->i_mapping);
> +	}

IFF we want a heuristic it should be a proper filemap_write_and_wait.  a
non-blocking start of I/O without waiting for it is snake oil.