rgw/cloud-transition: check bucket existence before create

Add HEAD request to check if target bucket exists before attempting
to create it. This avoids unnecessary PUT requests when the bucket
already exists on the remote endpoint.

Signed-off-by: Matthew N. Heler <matthew.heler@hotmail.com>

diff --git a/src/rgw/driver/rados/rgw_lc_tier.cc b/src/rgw/driver/rados/rgw_lc_tier.cc
index 046072e56516c6a62626018abc2427a926bec2e0..7e68a598fadc0bc2a17d788b4308cd0d488604df 100644 (file)
--- a/src/rgw/driver/rados/rgw_lc_tier.cc
+++ b/src/rgw/driver/rados/rgw_lc_tier.cc
@@ -1448,6 +1448,24 @@ static int cloud_tier_check_object(RGWLCCloudTierCtx& tier_ctx, bool& already_ti
   return ret;
 }
 
+static int cloud_tier_bucket_exists(RGWLCCloudTierCtx& tier_ctx)
+{
+  bufferlist out_bl;
+  string resource = tier_ctx.target_bucket_name;
+
+  int ret = tier_ctx.conn.send_resource(tier_ctx.dpp, "HEAD", resource,
+                                        nullptr, nullptr, out_bl, nullptr,
+                                        nullptr, null_yield);
+  if (ret == -ERR_NO_SUCH_BUCKET || ret == -ENOENT) {
+    return -ENOENT;
+  }
+  if (ret < 0) {
+    ldpp_dout(tier_ctx.dpp, 0) << "HEAD target bucket " << resource
+                               << " returned ret=" << ret << dendl;
+  }
+  return ret;
+}
+
 static int cloud_tier_create_bucket(RGWLCCloudTierCtx& tier_ctx) {
   bufferlist out_bl;
   int ret = 0;
@@ -1527,18 +1545,21 @@ static int cloud_tier_create_bucket(RGWLCCloudTierCtx& tier_ctx) {
 int rgw_cloud_tier_transfer_object(RGWLCCloudTierCtx& tier_ctx, std::set<std::string>& cloud_targets) {
   int ret = 0;
 
-  // check if target_path is already created
-  std::set<std::string>::iterator it;
-
-  it = cloud_targets.find(tier_ctx.target_bucket_name);
+  // check if target bucket is in local cache
+  auto it = cloud_targets.find(tier_ctx.target_bucket_name);
   tier_ctx.target_bucket_created = (it != cloud_targets.end());
 
-  /* If run first time attempt to create the target bucket */
   if (!tier_ctx.target_bucket_created) {
-    ret = cloud_tier_create_bucket(tier_ctx);
-
-    if (ret < 0) {
-      ldpp_dout(tier_ctx.dpp, 0) << "ERROR: failed to create target bucket on the cloud endpoint ret=" << ret << dendl;
+    // not in cache; check if bucket exists on remote
+    ret = cloud_tier_bucket_exists(tier_ctx);
+    if (ret == -ENOENT) {
+      ret = cloud_tier_create_bucket(tier_ctx);
+      if (ret < 0) {
+        ldpp_dout(tier_ctx.dpp, 0) << "ERROR: failed to create target bucket on the cloud endpoint ret=" << ret << dendl;
+        return ret;
+      }
+    } else if (ret < 0) {
+      ldpp_dout(tier_ctx.dpp, 0) << "ERROR: failed to check target bucket on the cloud endpoint ret=" << ret << dendl;
       return ret;
     }
     tier_ctx.target_bucket_created = true;