[sheepdog] [PATCH 1/2] sheep: introduce strict mode for write
Robin Dong
robin.k.dong at gmail.com
Wed Dec 11 03:59:27 CET 2013
Why not adding the check in gateway_forward_request() ? I think we should
check the copy number before send forward the request out.
2013/12/10 Liu Yuan <namei.unix at gmail.com>
> We make sure we write the exact number of copies to honor the promise of
> the
> redundancy for "strict mode". This means that after writing of targeted
> data,
> they are redundant as promised and can withstand the random node failures.
>
> For example, with a 4:2 policy, we need at least write to 6 nodes with data
> strip and parity strips. For non-strict mode, we allow to write
> successfully
> only if the data are written fully with 4 nodes alive.
>
> Signed-off-by: Liu Yuan <namei.unix at gmail.com>
> ---
> dog/cluster.c | 10 +++++++++-
> include/internal_proto.h | 2 ++
> include/sheep.h | 3 ++-
> include/sheepdog_proto.h | 2 +-
> sheep/ops.c | 2 +-
> sheep/request.c | 34 +++++++++++++++++++++++++++++++---
> 6 files changed, 46 insertions(+), 7 deletions(-)
>
> diff --git a/dog/cluster.c b/dog/cluster.c
> index 611c91d..43df232 100644
> --- a/dog/cluster.c
> +++ b/dog/cluster.c
> @@ -21,6 +21,8 @@ static struct sd_option cluster_options[] = {
> {'b', "store", true, "specify backend store"},
> {'c', "copies", true, "specify the default data redundancy (number
> of copies)"},
> {'f', "force", false, "do not prompt for confirmation"},
> + {'t', "strict", false,
> + "do not serve write request if number of nodes is not
> sufficient"},
> {'s', "backend", false, "show backend store information"},
> { 0, NULL, false, NULL },
> };
> @@ -30,6 +32,7 @@ static struct cluster_cmd_data {
> uint8_t copy_policy;
> bool force;
> bool show_store;
> + bool strict;
> char name[STORE_LEN];
> } cluster_cmd_data;
>
> @@ -117,6 +120,8 @@ static int cluster_format(int argc, char **argv)
> pstrcpy(store_name, STORE_LEN, DEFAULT_STORE);
> hdr.data_length = strlen(store_name) + 1;
> hdr.flags |= SD_FLAG_CMD_WRITE;
> + if (cluster_cmd_data.strict)
> + hdr.cluster.flags |= SD_CLUSTER_FLAG_STRICT;
>
> printf("using backend %s store\n", store_name);
> ret = dog_exec_req(&sd_nid, &hdr, store_name);
> @@ -552,7 +557,7 @@ static int cluster_check(int argc, char **argv)
> static struct subcommand cluster_cmd[] = {
> {"info", NULL, "aprhs", "show cluster information",
> NULL, CMD_NEED_NODELIST, cluster_info, cluster_options},
> - {"format", NULL, "bcaph", "create a Sheepdog store",
> + {"format", NULL, "bctaph", "create a Sheepdog store",
> NULL, CMD_NEED_NODELIST, cluster_format, cluster_options},
> {"shutdown", NULL, "aph", "stop Sheepdog",
> NULL, 0, cluster_shutdown, cluster_options},
> @@ -597,6 +602,9 @@ static int cluster_parser(int ch, const char *opt)
> case 's':
> cluster_cmd_data.show_store = true;
> break;
> + case 't':
> + cluster_cmd_data.strict = true;
> + break;
> }
>
> return 0;
> diff --git a/include/internal_proto.h b/include/internal_proto.h
> index b224c49..ac4e3f8 100644
> --- a/include/internal_proto.h
> +++ b/include/internal_proto.h
> @@ -126,6 +126,8 @@
> #define SD_RES_CLUSTER_ERROR 0x91 /* Cluster driver error */
> #define SD_RES_OBJ_TAKEN 0x92 /* Object ID is taken up */
>
> +#define SD_CLUSTER_FLAG_STRICT 0x0001 /* Strict mode for write */
> +
> enum sd_status {
> SD_STATUS_OK = 1,
> SD_STATUS_WAIT,
> diff --git a/include/sheep.h b/include/sheep.h
> index 293e057..d460d54 100644
> --- a/include/sheep.h
> +++ b/include/sheep.h
> @@ -160,7 +160,8 @@ static inline const char *sd_strerror(int err)
> [SD_RES_WAIT_FOR_FORMAT] = "Waiting for cluster to be
> formatted",
> [SD_RES_WAIT_FOR_JOIN] = "Waiting for other nodes to join
> cluster",
> [SD_RES_JOIN_FAILED] = "Node has failed to join cluster",
> - [SD_RES_HALT] = "IO has halted as there are no living
> nodes",
> + [SD_RES_HALT] =
> + "IO has halted as there are not enough living
> nodes",
> [SD_RES_READONLY] = "Object is read-only",
>
> /* from internal_proto.h */
> diff --git a/include/sheepdog_proto.h b/include/sheepdog_proto.h
> index cb47e3f..366499e 100644
> --- a/include/sheepdog_proto.h
> +++ b/include/sheepdog_proto.h
> @@ -156,7 +156,7 @@ struct sd_req {
> uint64_t ctime;
> uint8_t copies;
> uint8_t copy_policy;
> - uint8_t reserved[2];
> + uint16_t flags;
> uint32_t tag;
> } cluster;
> struct {
> diff --git a/sheep/ops.c b/sheep/ops.c
> index 75a2565..1e9bc1e 100644
> --- a/sheep/ops.c
> +++ b/sheep/ops.c
> @@ -271,7 +271,7 @@ static int cluster_make_fs(const struct sd_req *req,
> struct sd_rsp *rsp,
>
> sys->cinfo.nr_copies = req->cluster.copies;
> sys->cinfo.copy_policy = req->cluster.copy_policy;
> - sys->cinfo.flags = req->flags;
> + sys->cinfo.flags = req->cluster.flags;
> if (!sys->cinfo.nr_copies)
> sys->cinfo.nr_copies = SD_DEFAULT_COPIES;
> sys->cinfo.ctime = req->cluster.ctime;
> diff --git a/sheep/request.c b/sheep/request.c
> index 5113fca..fd54253 100644
> --- a/sheep/request.c
> +++ b/sheep/request.c
> @@ -284,6 +284,22 @@ static void queue_peer_request(struct request *req)
> queue_work(sys->io_wqueue, &req->work);
> }
>
> +/*
> + * We make sure we write the exact number of copies to honor the promise
> of the
> + * redundancy for strict mode. This means that after writing of targeted
> data,
> + * they are redundant as promised and can withstand the random node
> failures.
> + *
> + * For example, with a 4:2 policy, we need at least write to 6 nodes with
> data
> + * strip and parity strips. For non-strict mode, we allow to write
> successfully
> + * only if the data are written fully with 4 nodes alive.
> + */
> +static bool has_enough_zones(struct request *req)
> +{
> + uint64_t oid = req->rq.obj.oid;
> +
> + return req->vinfo->nr_zones >=
> get_vdi_copy_number(oid_to_vid(oid));
> +}
> +
> static void queue_gateway_request(struct request *req)
> {
> struct sd_req *hdr = &req->rq;
> @@ -310,13 +326,25 @@ static void queue_gateway_request(struct request
> *req)
> queue_work:
> if (RB_EMPTY_ROOT(&req->vinfo->vroot)) {
> sd_err("there is no living nodes");
> - req->rp.result = SD_RES_HALT;
> - put_request(req);
> - return;
> + goto end_request;
> + }
> + if (sys->cinfo.flags & SD_CLUSTER_FLAG_STRICT &&
> + hdr->flags & SD_FLAG_CMD_WRITE &&
> + !(hdr->flags & SD_FLAG_CMD_RECOVERY) &&
> + !has_enough_zones(req)) {
> + sd_err("not enough zones available");
> + goto end_request;
> }
> +
> req->work.fn = do_process_work;
> req->work.done = gateway_op_done;
> queue_work(sys->gateway_wqueue, &req->work);
> + return;
> +
> +end_request:
> + req->rp.result = SD_RES_HALT;
> + put_request(req);
> + return;
> }
>
> static void queue_local_request(struct request *req)
> --
> 1.7.9.5
>
> --
> sheepdog mailing list
> sheepdog at lists.wpkg.org
> http://lists.wpkg.org/mailman/listinfo/sheepdog
>
--
--
Best Regard
Robin Dong
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