[Sheepdog] [PATCH 1/3] sheep: unify cow object and regular object writing path

[Christoph Hellwig]

On Sun, Nov 20, 2011 at 07:11:25PM +0800, Liu Yuan wrote:
> From: Liu Yuan <tailai.ly at taobao.com>
> 
> This is necessary to do further unifying of sheep requests handling.
> 
> small changes on other:
>  - rename read_from_one into do_read_copy and make it return sd result.
>  - rename read_from_other_sheep into read_copy_from_cluster

Is there any good reason to even keep read_from_other_sheep /
read_from_other_sheep instead of opencoding it?  I'd rather merge it
into read_from_one / do_read_copy, and while at it make the length
parameter to it a normal scalar argument instead of a pointer, and
reject short reads.

> @@ -636,7 +635,7 @@ static int store_write_obj(struct request *req, uint32_t epoch)
>  	return ret;
>  }
>  
> -static int store_create_and_write_obj_cow(struct request *req, uint32_t epoch)
> +static int store_create_and_write_obj(struct request *req, uint32_t epoch)
>  {
>  	struct sd_obj_req *hdr = (struct sd_obj_req *)&req->rq;
>  	int ret;
> @@ -654,30 +653,24 @@ static int store_create_and_write_obj_cow(struct request *req, uint32_t epoch)
>  	ret = store.open(hdr->oid, &iocb, 1);
>  	if (ret != SD_RES_SUCCESS)
>  		return ret;
> -
> -	dprintf("%" PRIu64 ", %" PRIx64 "\n", hdr->oid, hdr->cow_oid);
> -
> -	buf = valloc(SD_DATA_OBJ_SIZE);
> -	if (!buf) {
> -		eprintf("failed to allocate memory\n");
> -		ret = SD_RES_NO_MEM;
> -		goto out;
> -	}
> -	ret = read_from_other_sheep(req, hdr->epoch, hdr->cow_oid, buf,
> -				     hdr->copies);
> -	if (ret) {
> -		eprintf("failed to read old object\n");
> -		ret = SD_RES_EIO;
> -		goto out;
> -	}
> -	iocb.buf = buf;
> -	iocb.length = SD_DATA_OBJ_SIZE;
> -	iocb.offset = 0;
> -	ret = store.write(hdr->oid, &iocb);
> -	if (ret != SD_RES_SUCCESS) {
> -		goto out;
> +	if (hdr->flags & SD_FLAG_CMD_COW) {
> +		dprintf("%" PRIu64 ", %" PRIx64 "\n", hdr->oid, hdr->cow_oid);
> +
> +		buf = xzalloc(SD_DATA_OBJ_SIZE);

This seems to drop error handling for the memory allocation