[Ocfs2-tools-devel] Re: [PATCH 1/2] The io_cache implementation

[tao.ma]

Joel Becker wrote:
> +static errcode_t io_cache_read_block(io_channel *channel, int64_t blkno,
> +				     int count, char *data)
> +
> +{
> +	int i;
> +	errcode_t ret = 0;
> +
> +	for (i = 0; i < count; i++, blkno++) {
> +		ret = io_cache_read_one_block(channel, blkno, data);
>   
Should data change accordingly? data + i * channel->io_blksize?
The same error happens in io_cache_write_block.
> +		if (ret)
> +			break;
> +	}
> +
> +	return ret;
> +}
> +
> +static errcode_t io_cache_write_one_block(io_channel *channel,
> +					  int64_t blkno, const char *data)
> +{
> +	errcode_t ret;
> +	struct io_cache *ic = channel->io_cache;
> +	struct io_cache_block *icb;
> +
> +	icb = io_cache_lookup(ic, blkno);
> +	if (icb)
> +		goto found;
> +
> +	/*
> +	 * Ok, this blkno isn't in the cache.  Steal something.
> +	 */
> +	icb = list_entry(ic->ic_lru.next, struct io_cache_block, icb_list);
> +	if (icb->icb_node.rb_parent) {
> +		rb_erase(&icb->icb_node, &ic->ic_lookup);
> +		memset(&icb->icb_node, 0, sizeof(struct rb_node));
> +	}
> +
> +	icb->icb_blkno = blkno;
> +	io_cache_insert(ic, icb);
> +
> +found:
> +	memcpy(icb->icb_buf, data, channel->io_blksize);
> +	io_cache_seen(ic, icb);
> +
> +	ret = unix_io_write_block(channel, blkno, 1, icb->icb_buf);
> +	return ret;
> +}
>   
I think the "memcpy" should be moved after the success of 
"unix_io_write_block" so that we can keep consistent of the buffer and 
the real content on the disk.
> +
> +static errcode_t io_cache_write_block(io_channel *channel, int64_t blkno,
> +				      int count, const char *data)
> +
> +{
> +	int i;
> +	errcode_t ret = 0;
> +
> +	for (i = 0; i < count; i++, blkno++) {
> +		ret = io_cache_write_one_block(channel, blkno, data);
> +		if (ret)
> +			break;
> +	}
> +
> +	return ret;
> +}
> +
> +
Tao