From c61bca6d6bac33e6d5c5af8b0f9ec77a229179d3 Mon Sep 17 00:00:00 2001
From: Ronen Friedman <rfriedma@redhat.com>
Date: Fri, 5 Jan 2024 09:07:19 -0600
Subject: [PATCH] osd/scrub: add "queue my request" flag to replica reservation
 messages

Up-to-date primaries will set this flag when sending a reservation
request. The replica OSD, if too busy to handle the request immediately, will queue
it until such time that the number of concurrent reservations is below the
configured limit. The queued requests are honored in FIFO order.

Old primaries will not set this flag, and will receive the expected
grant or deny reply immediately.

Signed-off-by: Ronen Friedman <rfriedma@redhat.com>
---
 src/messages/MOSDScrubReserve.h | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/src/messages/MOSDScrubReserve.h b/src/messages/MOSDScrubReserve.h
index 97b6dff4dd006..a2670a8e110f8 100644
--- a/src/messages/MOSDScrubReserve.h
+++ b/src/messages/MOSDScrubReserve.h
@@ -19,7 +19,7 @@
 
 class MOSDScrubReserve : public MOSDFastDispatchOp {
 private:
-  static constexpr int HEAD_VERSION = 2;
+  static constexpr int HEAD_VERSION = 3;
   static constexpr int COMPAT_VERSION = 1;
 public:
   using reservation_nonce_t = uint32_t;
@@ -35,6 +35,9 @@ public:
   int32_t type;
   pg_shard_t from;
   reservation_nonce_t reservation_nonce{0};
+  /// 'false' if the (legacy) primary is expecting an immediate
+  /// granted / denied response
+  bool wait_for_resources{false};
 
   epoch_t get_map_epoch() const override {
     return map_epoch;
@@ -48,12 +51,12 @@ public:
       map_epoch(0), type(-1) {}
   MOSDScrubReserve(spg_t pgid,
 		   epoch_t map_epoch,
-		   int type,
+		   ReserveMsgOp type_code,
 		   pg_shard_t from,
 		   reservation_nonce_t nonce)
     : MOSDFastDispatchOp{MSG_OSD_SCRUB_RESERVE, HEAD_VERSION, COMPAT_VERSION},
       pgid(pgid), map_epoch(map_epoch),
-      type(type), from(from), reservation_nonce{nonce} {}
+      type(static_cast<int32_t>(type_code)), from(from), reservation_nonce{nonce} {}
 
   std::string_view get_type_name() const {
     return "MOSDScrubReserve";
@@ -63,7 +66,7 @@ public:
     out << "MOSDScrubReserve(" << pgid << " ";
     switch (type) {
     case REQUEST:
-      out << "REQUEST ";
+      out << (wait_for_resources ? "QREQUEST " : "REQUEST ");
       break;
     case GRANT:
       out << "GRANT ";
@@ -89,10 +92,16 @@ public:
     decode(from, p);
     if (header.version >= 2) {
       decode(reservation_nonce, p);
+      if (header.version >= 3) {
+        decode(wait_for_resources, p);
+      } else {
+        wait_for_resources = false;
+      }
     } else {
       // a zero nonce (identifying legacy senders) is ignored when
       // checking the request for obsolescence
       reservation_nonce = 0;
+      wait_for_resources = false;
     }
   }
 
@@ -103,6 +112,7 @@ public:
     encode(type, payload);
     encode(from, payload);
     encode(reservation_nonce, payload);
+    encode(wait_for_resources, payload);
   }
 private:
   template<class T, typename... Args>
-- 
2.39.5