From 8eb51539bb64840a043c59f99e28478f327877b5 Mon Sep 17 00:00:00 2001
From: lisali <xiaoyan.li@intel.com>
Date: Tue, 13 Jun 2017 09:44:25 -0400
Subject: [PATCH] bluestore: wrap blob id when it reaches maximum value of
 int16_t

Blob id exceeds maximum value, this patch is to prevent it.
Fixes: http://tracker.ceph.com/issues/19555

Signed-off-by: Xiaoyan Li <xiaoyan.li@intel.com>
---
 src/os/bluestore/BlueStore.cc | 35 +++++++++++++++++++++++++++--------
 src/os/bluestore/BlueStore.h  |  1 +
 2 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/src/os/bluestore/BlueStore.cc b/src/os/bluestore/BlueStore.cc
index e8998683392..2252dd89c16 100644
--- a/src/os/bluestore/BlueStore.cc
+++ b/src/os/bluestore/BlueStore.cc
@@ -36,6 +36,8 @@
 #define dout_context cct
 #define dout_subsys ceph_subsys_bluestore
 
+using bid_t = decltype(BlueStore::Blob::id);
+
 // bluestore_cache_onode
 MEMPOOL_DEFINE_OBJECT_FACTORY(BlueStore::Onode, bluestore_onode,
 			      bluestore_cache_onode);
@@ -661,7 +663,7 @@ void BlueStore::GarbageCollector::process_protrusive_extents(
             }
             bExit = it == bi.last_lextent;
             ++it;
-          } while(!bExit);
+          } while (!bExit);
         }
         expected_for_release += blob_expected_for_release;
         expected_allocations += bi.expected_allocations;
@@ -2019,6 +2021,28 @@ void BlueStore::ExtentMap::update(KeyValueDB::Transaction t,
   }
 }
 
+bid_t BlueStore::ExtentMap::allocate_spanning_blob_id()
+{
+  if (spanning_blob_map.empty())
+    return 0;
+  bid_t bid = spanning_blob_map.rbegin()->first + 1;
+  // bid is valid and available.
+  if (bid >= 0)
+    return bid;
+  // Find next unused bid;
+  bid = rand() % (numeric_limits<bid_t>::max() + 1);
+  const auto begin_bid = bid;
+  do {
+    if (!spanning_blob_map.count(bid))
+      return bid;
+    else {
+      bid++;
+      if (bid < 0) bid = 0;
+    }
+  } while (bid != begin_bid);
+  assert(0 == "no available blob id");
+}
+
 void BlueStore::ExtentMap::reshard(
   KeyValueDB *db,
   KeyValueDB::Transaction t)
@@ -2208,12 +2232,6 @@ void BlueStore::ExtentMap::reshard(
     } else {
       shard_end = sp->offset;
     }
-    int bid;
-    if (spanning_blob_map.empty()) {
-      bid = 0;
-    } else {
-      bid = spanning_blob_map.rbegin()->first + 1;
-    }
     Extent dummy(needs_reshard_begin);
     for (auto e = extent_map.lower_bound(dummy); e != extent_map.end(); ++e) {
       if (e->logical_offset >= needs_reshard_end) {
@@ -2267,7 +2285,8 @@ void BlueStore::ExtentMap::reshard(
 	    must_span = true;
 	  }
 	  if (must_span) {
-	    b->id = bid++;
+            auto bid = allocate_spanning_blob_id();
+            b->id = bid;
 	    spanning_blob_map[b->id] = b;
 	    dout(20) << __func__ << "    adding spanning " << *b << dendl;
 	  }
diff --git a/src/os/bluestore/BlueStore.h b/src/os/bluestore/BlueStore.h
index de347ec9855..236ebba28ae 100644
--- a/src/os/bluestore/BlueStore.h
+++ b/src/os/bluestore/BlueStore.h
@@ -776,6 +776,7 @@ public:
     }
 
     void update(KeyValueDB::Transaction t, bool force);
+    decltype(BlueStore::Blob::id) allocate_spanning_blob_id();
     void reshard(
       KeyValueDB *db,
       KeyValueDB::Transaction t);
-- 
2.39.5