rbd-mirror: prune unnecessary non-primary mirror snapshots

Once a non-primary snapshot is no longer required for syncing, delete it
from the image.

Fixes: https://tracker.ceph.com/issues/44105
Signed-off-by: Jason Dillaman <dillaman@redhat.com>

diff --git a/src/test/rbd_mirror/image_replayer/snapshot/test_mock_Replayer.cc b/src/test/rbd_mirror/image_replayer/snapshot/test_mock_Replayer.cc
index 4995347a6f9b79ec310daca98c5cd064d7234309..17407e0e466533e1f0e8f7d7ada4ef9c26f3c793 100644 (file)
--- a/src/test/rbd_mirror/image_replayer/snapshot/test_mock_Replayer.cc
+++ b/src/test/rbd_mirror/image_replayer/snapshot/test_mock_Replayer.cc
@@ -18,6 +18,7 @@
 #include "tools/rbd_mirror/image_replayer/snapshot/StateBuilder.h"
 #include "test/librados_test_stub/MockTestMemIoCtxImpl.h"
 #include "test/librbd/mock/MockImageCtx.h"
+#include "test/librbd/mock/MockOperations.h"
 #include "test/rbd_mirror/mock/MockContextWQ.h"
 #include "test/rbd_mirror/mock/MockSafeTimer.h"
 
@@ -456,6 +457,22 @@ public:
       }));
   }
 
+  void expect_prune_non_primary_snapshot(librbd::MockTestImageCtx& mock_image_ctx,
+                                         uint64_t snap_id, int r) {
+    EXPECT_CALL(mock_image_ctx, get_snap_info(snap_id))
+      .WillOnce(Invoke([&mock_image_ctx](uint64_t snap_id) -> librbd::SnapInfo* {
+        auto it = mock_image_ctx.snap_info.find(snap_id);
+        if (it == mock_image_ctx.snap_info.end()) {
+          return nullptr;
+        }
+        return &it->second;
+      }));
+    EXPECT_CALL(*mock_image_ctx.operations, snap_remove(_, _, _))
+      .WillOnce(WithArg<2>(Invoke([this, r](Context* ctx) {
+        m_threads->work_queue->queue(ctx, r);
+      })));
+  }
+
   void expect_snapshot_copy(MockSnapshotCopyRequest& mock_snapshot_copy_request,
                             uint64_t src_snap_id_start,
                             uint64_t src_snap_id_end,
@@ -786,7 +803,7 @@ TEST_F(TestMockImageReplayerSnapshotReplayer, SyncSnapshot) {
                      0);
   expect_notify_sync_complete(mock_instance_watcher, mock_local_image_ctx.id);
 
-  // idle
+  // prune non-primary snap1
   expect_load_image_meta(mock_image_meta, false, 0);
   expect_is_refresh_required(mock_local_image_ctx, true);
   expect_refresh(
@@ -803,6 +820,19 @@ TEST_F(TestMockImageReplayerSnapshotReplayer, SyncSnapshot) {
        0, {}, 0, 0, {}}},
     }, 0);
   expect_is_refresh_required(mock_remote_image_ctx, false);
+  expect_prune_non_primary_snapshot(mock_local_image_ctx, 11, 0);
+
+  // idle
+  expect_load_image_meta(mock_image_meta, false, 0);
+  expect_is_refresh_required(mock_local_image_ctx, true);
+  expect_refresh(
+    mock_local_image_ctx, {
+      {14U, librbd::SnapInfo{"snap4", cls::rbd::MirrorSnapshotNamespace{
+         cls::rbd::MIRROR_SNAPSHOT_STATE_NON_PRIMARY, {}, "remote mirror uuid",
+         4, true, 0, {}},
+       0, {}, 0, 0, {}}},
+    }, 0);
+  expect_is_refresh_required(mock_remote_image_ctx, false);
 
   // fire init
   C_SaferCond init_ctx;

diff --git a/src/tools/rbd_mirror/image_replayer/snapshot/Replayer.cc b/src/tools/rbd_mirror/image_replayer/snapshot/Replayer.cc
index 1979f5c5a1bce0d0cc41b650ca1b6ad93f63394a..a28cb82e3bfa99521874750a7bceccac225c1c55 100644 (file)
--- a/src/tools/rbd_mirror/image_replayer/snapshot/Replayer.cc
+++ b/src/tools/rbd_mirror/image_replayer/snapshot/Replayer.cc
@@ -11,6 +11,7 @@
 #include "json_spirit/json_spirit.h"
 #include "librbd/ImageCtx.h"
 #include "librbd/ImageState.h"
+#include "librbd/Operations.h"
 #include "librbd/Utils.h"
 #include "librbd/deep_copy/Handler.h"
 #include "librbd/deep_copy/ImageCopyRequest.h"
@@ -29,6 +30,7 @@
 #include "tools/rbd_mirror/image_replayer/snapshot/ApplyImageStateRequest.h"
 #include "tools/rbd_mirror/image_replayer/snapshot/StateBuilder.h"
 #include "tools/rbd_mirror/image_replayer/snapshot/Utils.h"
+#include <set>
 
 #define dout_context g_ceph_context
 #define dout_subsys ceph_subsys_rbd_mirror
@@ -416,6 +418,8 @@ void Replayer<I>::scan_local_mirror_snapshots(
   m_remote_snap_id_end = CEPH_NOSNAP;
   m_remote_mirror_snap_ns = {};
 
+  std::set<uint64_t> prune_snap_ids;
+
   auto local_image_ctx = m_state_builder->local_image_ctx;
   std::shared_lock image_locker{local_image_ctx->image_lock};
   for (auto snap_info_it = local_image_ctx->snap_info.begin();
@@ -437,10 +441,24 @@ void Replayer<I>::scan_local_mirror_snapshots(
         // if remote has new snapshots, we would sync from here
         m_local_snap_id_start = local_snap_id;
         m_local_snap_id_end = CEPH_NOSNAP;
+
+        if (mirror_ns->mirror_peer_uuids.empty()) {
+          // no other peer will attempt to sync to this snapshot so store as
+          // a candidate for removal
+          prune_snap_ids.insert(local_snap_id);
+        }
       } else {
         // start snap will be last complete mirror snapshot or initial
         // image revision
         m_local_snap_id_end = local_snap_id;
+
+        if (mirror_ns->last_copied_object_number == 0) {
+          // snapshot might be missing image state, object-map, etc, so just
+          // delete and re-create it if we haven't started copying data
+          // objects
+          prune_snap_ids.insert(local_snap_id);
+          break;
+        }
       }
     } else if (mirror_ns->is_primary()) {
       if (mirror_ns->complete) {
@@ -461,6 +479,19 @@ void Replayer<I>::scan_local_mirror_snapshots(
   }
   image_locker.unlock();
 
+  if (m_local_snap_id_start > 0 && m_local_snap_id_end == CEPH_NOSNAP) {
+    // remove candidate that is required for delta snapshot sync
+    prune_snap_ids.erase(m_local_snap_id_start);
+  }
+  if (!prune_snap_ids.empty()) {
+    locker->unlock();
+
+    auto prune_snap_id = *prune_snap_ids.begin();
+    dout(5) << "pruning unused non-primary snapshot " << prune_snap_id << dendl;
+    prune_non_primary_snapshot(prune_snap_id);
+    return;
+  }
+
   if (m_local_snap_id_start > 0 || m_local_snap_id_end != CEPH_NOSNAP) {
     if (m_local_mirror_snap_ns.is_non_primary() &&
         m_local_mirror_snap_ns.primary_mirror_uuid !=
@@ -656,6 +687,56 @@ void Replayer<I>::scan_remote_mirror_snapshots(
   notify_status_updated();
 }
 
+template <typename I>
+void Replayer<I>::prune_non_primary_snapshot(uint64_t snap_id) {
+  dout(10) << "snap_id=" << snap_id << dendl;
+
+  auto local_image_ctx = m_state_builder->local_image_ctx;
+  bool snap_valid = false;
+  cls::rbd::SnapshotNamespace snap_namespace;
+  std::string snap_name;
+
+  {
+    std::shared_lock image_locker{local_image_ctx->image_lock};
+    auto snap_info = local_image_ctx->get_snap_info(snap_id);
+    if (snap_info != nullptr) {
+      snap_valid = true;
+      snap_namespace = snap_info->snap_namespace;
+      snap_name = snap_info->name;
+
+      ceph_assert(boost::get<cls::rbd::MirrorSnapshotNamespace>(
+        &snap_namespace) != nullptr);
+    }
+  }
+
+  if (!snap_valid) {
+    load_local_image_meta();
+    return;
+  }
+
+  auto ctx = create_context_callback<
+    Replayer<I>, &Replayer<I>::handle_prune_non_primary_snapshot>(this);
+  local_image_ctx->operations->snap_remove(snap_namespace, snap_name, ctx);
+}
+
+template <typename I>
+void Replayer<I>::handle_prune_non_primary_snapshot(int r) {
+  dout(10) << "r=" << r << dendl;
+
+  if (r < 0 && r != -ENOENT) {
+    derr << "failed to prune non-primary snapshot: " << cpp_strerror(r)
+         << dendl;
+    handle_replay_complete(r, "failed to prune non-primary snapshot");
+    return;
+  }
+
+  if (is_replay_interrupted()) {
+    return;
+  }
+
+  load_local_image_meta();
+}
+
 template <typename I>
 void Replayer<I>::copy_snapshots() {
   dout(10) << "remote_snap_id_start=" << m_remote_snap_id_start << ", "

diff --git a/src/tools/rbd_mirror/image_replayer/snapshot/Replayer.h b/src/tools/rbd_mirror/image_replayer/snapshot/Replayer.h
index 4a96291d614e3be8ee7d704d42e3c14d8f6abf63..1b50a3d1489ff6251c6c22c03e741f3df2fe462b 100644 (file)
--- a/src/tools/rbd_mirror/image_replayer/snapshot/Replayer.h
+++ b/src/tools/rbd_mirror/image_replayer/snapshot/Replayer.h
@@ -115,6 +115,9 @@ private:
    *    v (skip if not needed)                          |
    * REFRESH_REMOTE_IMAGE                               |
    *    |                                               |
+   *    | (unused non-primary snapshot)                 |
+   *    |\--------------> PRUNE_NON_PRIMARY_SNAPSHOT---/|
+   *    |                                               |
    *    | (interrupted sync)                            |
    *    |\--------------> GET_LOCAL_IMAGE_STATE ------\ |
    *    |                                             | |
@@ -252,6 +255,9 @@ private:
   void scan_local_mirror_snapshots(std::unique_lock<ceph::mutex>* locker);
   void scan_remote_mirror_snapshots(std::unique_lock<ceph::mutex>* locker);
 
+  void prune_non_primary_snapshot(uint64_t snap_id);
+  void handle_prune_non_primary_snapshot(int r);
+
   void copy_snapshots();
   void handle_copy_snapshots(int r);