From: Tianshan Qu <tianshan@xsky.com>
Date: Tue, 23 Jul 2019 09:59:09 +0000 (+0800)
Subject: rgw: gc remove tag after all sub io finish
X-Git-Tag: v14.2.8~28^2~2^2~14^2
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=3fd05da32a9f47f0bd37941397656b615f217940;p=ceph.git

rgw: gc remove tag after all sub io finish

now gc add tag to remove queue just after first shadow io finish,
so if following shadows have any delete failure, there will be no
chance to retry, since gc tag entry have been removed

Fixes: http://tracker.ceph.com/issues/40903

Signed-off-by: Tianshan Qu <tianshan@xsky.com>
(cherry picked from commit 9ec4427199794566da78098b199a84f0afd17415)
---

diff --git a/src/rgw/rgw_gc.cc b/src/rgw/rgw_gc.cc
index 0e796f99a75d..0b99e0870718 100644
--- a/src/rgw/rgw_gc.cc
+++ b/src/rgw/rgw_gc.cc
@@ -151,6 +151,10 @@ class RGWGCIOManager {
 
   deque<IO> ios;
   vector<std::vector<string> > remove_tags;
+  /* tracks the number of remaining shadow objects for a given tag in order to
+   * only remove the tag once all shadow objects have themselves been removed
+   */
+  vector<map<string, size_t> > tag_io_size;
 
 #define MAX_AIO_DEFAULT 10
   size_t max_aio{MAX_AIO_DEFAULT};
@@ -159,7 +163,8 @@ public:
   RGWGCIOManager(const DoutPrefixProvider* _dpp, CephContext *_cct, RGWGC *_gc) : dpp(_dpp),
                                                   cct(_cct),
                                                   gc(_gc),
-                                                  remove_tags(cct->_conf->rgw_gc_max_objs) {
+                                                  remove_tags(cct->_conf->rgw_gc_max_objs),
+                                                  tag_io_size(cct->_conf->rgw_gc_max_objs) {
     max_aio = cct->_conf->rgw_gc_max_concurrent_io;
   }
 
@@ -219,20 +224,38 @@ public:
     ios.pop_front();
   }
 
+  /* This is a request to schedule a tag removal. It will be called once when
+   * there are no shadow objects. But it will also be called for every shadow
+   * object when there are any. Since we do not want the tag to be removed
+   * until all shadow objects have been successfully removed, the scheduling
+   * will not happen until the shadow object count goes down to zero
+   */
   void schedule_tag_removal(int index, string tag) {
+    auto& ts = tag_io_size[index];
+    auto ts_it = ts.find(tag);
+    if (ts_it != ts.end()) {
+      auto& size = ts_it->second;
+      --size;
+      // wait all shadow obj delete return
+      if (size != 0)
+        return;
+
+      ts.erase(ts_it);
+    }
+
     auto& rt = remove_tags[index];
 
-    // since every element of a chain tries to add the same tag, and
-    // since chains are handled sequentially, check to make sure it's
-    // not already on the list
-    if (rt.empty() || rt.back() != tag) {
-      rt.push_back(tag);
-      if (rt.size() >= (size_t)cct->_conf->rgw_gc_max_trim_chunk) {
-	flush_remove_tags(index, rt);
-      }
+    rt.push_back(tag);
+    if (rt.size() >= (size_t)cct->_conf->rgw_gc_max_trim_chunk) {
+      flush_remove_tags(index, rt);
     }
   }
 
+  void add_tag_io_size(int index, string tag, size_t size) {
+    auto& ts = tag_io_size[index];
+    ts.emplace(tag, size);
+  }
+
   void drain_ios() {
     while (!ios.empty()) {
       if (gc->going_down()) {
@@ -364,6 +387,7 @@ int RGWGC::process(int index, int max_secs, bool expired_only,
       if (chain.objs.empty()) {
         io_manager.schedule_tag_removal(index, info.tag);
       } else {
+        io_manager.add_tag_io_size(index, info.tag, chain.objs.size());
 	for (liter = chain.objs.begin(); liter != chain.objs.end(); ++liter) {
 	  cls_rgw_obj& obj = *liter;