[sheepdog] [PATCH] sheep:Fix data wipe bug in recovery

[徐小龙]

Epoch won't increase if there are only gateway nodes in the cluster.
In this way, when the cluster restarts, it will always recovery from a
latest epoch version which has at least one non-gateway node in the cluster.
This patch fixes bug "data wipe bug in the recovery" described here:
        https://bugs.launchpad.net/sheepdog-project/+bug/1327037

        modified:   sheep/store.c
Reported by:Xiaolong Xu <nxtxiaolong at gmail.com>; Yang Zhang <
zhangyangdreamer at gmail.com>
---
 sheep/store.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/sheep/store.c b/sheep/store.c
index 8843fb8..ca16284 100644
--- a/sheep/store.c
+++ b/sheep/store.c
@@ -19,9 +19,10 @@ LIST_HEAD(store_drivers);

 int update_epoch_log(uint32_t epoch, struct sd_node *nodes, size_t
nr_nodes)
 {
-       int ret, len, nodes_len;
+       int ret = 0, len, nodes_len;
        time_t t;
        char path[PATH_MAX], *buf;
+       bool all_gateway = true;

        sd_debug("update epoch: %d, %zu", epoch, nr_nodes);

@@ -37,14 +38,19 @@ int update_epoch_log(uint32_t epoch, struct sd_node
*nodes, size_t nr_nodes)
         * rb field is unused in epoch file, zero-filling it
         * is good for epoch file recovery because it is unified
         */
-       for (int i = 0; i < nr_nodes; i++)
+       for (int i = 0; i < nr_nodes; i++){
+               if((nodes + i)->nr_vnodes){
+                       all_gateway = false;
+               }
                memset(buf + i * sizeof(struct sd_node)
                                + offsetof(struct sd_node, rb),
                                0, sizeof(struct rb_node));
+       }

        snprintf(path, sizeof(path), "%s%08u", epoch_path, epoch);
-
-       ret = atomic_create_and_write(path, buf, len, true);
+       if(!all_gateway){
+               ret = atomic_create_and_write(path, buf, len, true);
+       }

        free(buf);
        return ret;
-- 
1.9.1
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