From ab30ff20d6c55a69e6298362c15190def1567da7 Mon Sep 17 00:00:00 2001
From: Varada Kari <varada.kari@sandisk.com>
Date: Fri, 15 May 2015 18:39:10 +0530
Subject: [PATCH] KeyValueStore: optimize the object header writes

Don't write the object header when any strip is overwritten.
write header when new strip is added or any header fields are modified.

Signed-off-by: Varada Kari <varada.kari@sandisk.com>
---
 src/os/KeyValueStore.cc | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/src/os/KeyValueStore.cc b/src/os/KeyValueStore.cc
index 589227f987f..f93be78f9bc 100644
--- a/src/os/KeyValueStore.cc
+++ b/src/os/KeyValueStore.cc
@@ -98,6 +98,7 @@ int StripObjectMap::save_strip_header(StripObjectHeaderRef strip_header,
     ::encode(*strip_header, strip_header->header->data);
 
     set_header(strip_header->cid, strip_header->oid, *(strip_header->header), t);
+    strip_header->updated = false;
   }
   return 0;
 }
@@ -462,11 +463,13 @@ int KeyValueStore::BufferTransaction::submit_transaction()
     if (header->deleted)
       continue;
 
-    r = store->backend->save_strip_header(header, t);
+    if (header->updated) {
+      r = store->backend->save_strip_header(header, t);
 
-    if (r < 0) {
-      dout(10) << __func__ << " save strip header failed " << dendl;
-      goto out;
+      if (r < 0) {
+        dout(10) << __func__ << " save strip header failed " << dendl;
+        goto out;
+      }
     }
   }
 
@@ -1871,6 +1874,7 @@ int KeyValueStore::_generic_write(StripObjectMap::StripObjectHeaderRef header,
   if (len + offset > header->max_size) {
     header->max_size = len + offset;
     header->bits.resize(header->max_size/header->strip_size+1);
+    header->updated = true;
   }
 
   vector<StripObjectMap::StripExtent> extents;
@@ -1931,13 +1935,13 @@ int KeyValueStore::_generic_write(StripObjectMap::StripObjectHeaderRef header,
         value.append_zero(header->strip_size-value.length());
 
       header->bits[iter->no] = 1;
+      header->updated = true;
     }
     assert(value.length() == header->strip_size);
     values[key].swap(value);
   }
   assert(bl_offset == len);
 
-  header->updated = true;
   t.set_buffer_keys(header, OBJECT_STRIP_PREFIX, values);
   dout(10) << __func__ << " " << header->cid << "/" << header->oid << " "
            << offset << "~" << len << " = " << r << dendl;