From ac2c8083de2d05f59a90cdcf4df8f81add51f12e Mon Sep 17 00:00:00 2001
From: Sage Weil <sage@redhat.com>
Date: Tue, 3 May 2016 16:21:48 -0400
Subject: [PATCH] os/bluestore: keep an extent_ref_map for each blob

This lets us track which portions of a blob are still in use.  In some
cases, we may be able to split the blob to deallocate a portion of it.
In other cases, we will want this information to know whether to
recompress the blob (or whatever).

Signed-off-by: Sage Weil <sage@redhat.com>
---
 src/os/bluestore/bluestore_types.cc | 9 ++++++++-
 src/os/bluestore/bluestore_types.h  | 7 +++++--
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/src/os/bluestore/bluestore_types.cc b/src/os/bluestore/bluestore_types.cc
index ea73b8ba83d2d..8907f8148fb30 100644
--- a/src/os/bluestore/bluestore_types.cc
+++ b/src/os/bluestore/bluestore_types.cc
@@ -425,6 +425,7 @@ void bluestore_blob_t::encode(bufferlist& bl) const
   ::encode(csum_type, bl);
   ::encode(csum_block_order, bl);
   ::encode(num_refs, bl);
+  ::encode(ref_map, bl);
   ::encode(csum_data, bl);
   ENCODE_FINISH(bl);
 }
@@ -438,6 +439,7 @@ void bluestore_blob_t::decode(bufferlist::iterator& p)
   ::decode(csum_type, p);
   ::decode(csum_block_order, p);
   ::decode(num_refs, p);
+  ::decode(ref_map, p);
   ::decode(csum_data, p);
   DECODE_FINISH(p);
 }
@@ -454,6 +456,7 @@ void bluestore_blob_t::dump(Formatter *f) const
   f->dump_unsigned("csum_type", csum_type);
   f->dump_unsigned("csum_block_order", csum_block_order);
   f->dump_unsigned("num_refs", num_refs);
+  f->dump_object("ref_map", ref_map);
   f->open_array_section("csum_data");
   size_t n = get_csum_count();
   for (unsigned i = 0; i < n; ++i)
@@ -469,19 +472,23 @@ void bluestore_blob_t::generate_test_instances(list<bluestore_blob_t*>& ls)
   ls.push_back(new bluestore_blob_t(4096, bluestore_pextent_t(111, 222), 12));
   ls.back()->csum_type = CSUM_XXHASH32;
   ls.back()->csum_block_order = 16;
-  ls.back()->num_refs = 2;
   ls.back()->csum_data = vector<char>{1, 2, 3, 4};  // one uint32_t
+  ls.back()->num_refs = 3;
 }
 
 ostream& operator<<(ostream& out, const bluestore_blob_t& o)
 {
   out << "blob(" << o.extents
       << " len " << o.length
+      << " nref " << o.num_refs
       << " " << o.get_flags_string();
   if (o.csum_type) {
     out << " csum " << o.get_csum_type_string(o.csum_type)
 	<< " order " << (int)o.csum_block_order;
   }
+  if (!o.ref_map.empty()) {
+    out << " ref_map " << o.ref_map;
+  }
   out << ")";
   return out;
 }
diff --git a/src/os/bluestore/bluestore_types.h b/src/os/bluestore/bluestore_types.h
index 800c691ed3d8f..a1cfe39a8381c 100644
--- a/src/os/bluestore/bluestore_types.h
+++ b/src/os/bluestore/bluestore_types.h
@@ -238,7 +238,8 @@ struct bluestore_blob_t {
   uint8_t csum_type;               ///< CSUM_*
   uint8_t csum_block_order;        ///< csum block size is 1<<block_order bytes
 
-  uint16_t num_refs;               ///< reference count (always 1 when in onode)
+  uint32_t num_refs;               ///< num lextents that point to me
+  bluestore_extent_ref_map_t ref_map; ///< references (empty when in onode)
   vector<char> csum_data;          ///< opaque vector of csum data
 
   bluestore_blob_t(uint32_t l = 0, uint32_t f = 0)
@@ -246,7 +247,8 @@ struct bluestore_blob_t {
       flags(f),
       csum_type(CSUM_NONE),
       csum_block_order(12),
-      num_refs(1) {}
+      num_refs(1) {
+  }
 
   bluestore_blob_t(uint32_t l, const bluestore_pextent_t& ext, uint32_t f = 0)
     : length(l),
@@ -381,6 +383,7 @@ ostream& operator<<(ostream& out, const bluestore_blob_t& o);
 /// blob id: positive = local, negative = shared bnode
 typedef int64_t bluestore_blob_id_t;
 
+
 /// lextent: logical data block back by the extent
 struct bluestore_lextent_t {
   static string get_flags_string(unsigned flags);
-- 
2.39.5