On 03/22/2012 04:40 PM, [email protected] wrote:
> From: HaiTing Yao <[email protected]>
>
> Doing snapshot COW:
>
> 1, If new writing request occurs and need COW for sanpshot, now read old
> object to buffer, then write the buffer to new object, then write the
> request data to new object. We can merge the latter two writing request.
>
> 2, If new writing request covers whole object, no need to read old
> object.
>
> After the modification, pass bigger buffer to do_write_obj when doing
> COW, but it will not add the burden. COW is never for inode object, so
> it will not use the journal.
>
> Signed-off-by: HaiTing Yao <[email protected]>
> ---
> sheep/store.c | 29 +++++++++++++++++------------
> 1 files changed, 17 insertions(+), 12 deletions(-)
>
> diff --git a/sheep/store.c b/sheep/store.c
> index dfec235..97f1f13 100644
> --- a/sheep/store.c
> +++ b/sheep/store.c
> @@ -640,6 +640,7 @@ int store_create_and_write_obj(const struct sd_req *req,
> struct sd_rsp *rsp, voi
> {
> struct sd_obj_req *hdr = (struct sd_obj_req *)req;
> struct request *request = (struct request *)data;
> + struct sd_obj_req cow_hdr;
> int ret;
> uint32_t epoch = hdr->epoch;
> char *buf = NULL;
> @@ -664,19 +665,23 @@ int store_create_and_write_obj(const struct sd_req
> *req, struct sd_rsp *rsp, voi
> dprintf("%" PRIu64 ", %" PRIx64 "\n", hdr->oid, hdr->cow_oid);
>
> buf = xzalloc(SD_DATA_OBJ_SIZE);
> - ret = read_copy_from_cluster(request, hdr->epoch, hdr->cow_oid,
> buf);
> - if (ret != SD_RES_SUCCESS) {
> - eprintf("failed to read cow object\n");
> - goto out;
> + if ((hdr->data_length != SD_DATA_OBJ_SIZE)
> + || (hdr->offset!= 0)) {
For create_and_write object, data_length of request is always
SD_DATA_OBJ_SIZE and offset always 0.
Thanks,
Yuan
> + ret = read_copy_from_cluster(request, hdr->epoch,
> hdr->cow_oid, buf);
> + if (ret != SD_RES_SUCCESS) {
> + eprintf("failed to read cow object\n");
> + goto out;
> + }
> }
> - iocb.buf = buf;
> - iocb.length = SD_DATA_OBJ_SIZE;
> - iocb.offset = 0;
> - ret = sd_store->write(hdr->oid, &iocb);
> - if (ret != SD_RES_SUCCESS)
> - goto out;
> - }
> - ret = do_write_obj(&iocb, hdr, epoch, request->data);
> +
> + memcpy(buf + hdr->offset, request->data, hdr->data_length);
> + memcpy(&cow_hdr, hdr, sizeof(cow_hdr));
> + cow_hdr.offset = 0;
> + cow_hdr.data_length = SD_DATA_OBJ_SIZE;
> +
> + ret = do_write_obj(&iocb, &cow_hdr, epoch, buf);
> + } else
> + ret = do_write_obj(&iocb, hdr, epoch, request->data);
> out:
> free(buf);
> sd_store->close(hdr->oid, &iocb);
--
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