Do not zero-fill newly allocated files on Windows

On Windows platforms code was added to zero-fill each newly allocated data file in order to work around Windows KB http://support.microsoft.com/kb/2731284. The KB only applies for Windows 7 and Windows 2008 Server installations, so there is no need to do it on each and every system.

This fix restricts the zeroing-out code to only versions, which have had the bug. It will not check whether the hot fix has been installed.

3 files changed, 33 insertions, 2 deletions

diff --git a/src/mongo/util/file_allocator.cpp b/src/mongo/util/file_allocator.cpp
index e59bce6934b..7876744f7d5 100644
--- a/src/mongo/util/file_allocator.cpp
+++ b/src/mongo/util/file_allocator.cpp
@@ -39,6 +39,7 @@
 #include "mongo/platform/posix_fadvise.h"
 #include "mongo/util/mongoutils/str.h"
 #include "mongo/util/paths.h"
+#include "mongo/util/processinfo.h"
 #include "mongo/util/time_support.h"
 #include "mongo/util/timer.h"
 
@@ -186,6 +187,15 @@ namespace mongo {
                      size - 1 == lseek(fd, size - 1, SEEK_SET) );
             uassert( 10442 ,  str::stream() << "Unable to allocate new file of size " << size << ' ' << errnoWithDescription(),
                      1 == write(fd, "", 1) );
+
+            // File expansion is completed here. Do not do the zeroing out on OS-es where there
+            // is no risk of triggering allocation-related bugs such as
+            // http://support.microsoft.com/kb/2731284.
+            //
+            if (!ProcessInfo::isDataFileZeroingNeeded()) {
+                return;
+            }
+
             lseek(fd, 0, SEEK_SET);
 
             const long z = 256 * 1024;
diff --git a/src/mongo/util/processinfo.h b/src/mongo/util/processinfo.h
index 8e9044d39e4..03fcdd85993 100644
--- a/src/mongo/util/processinfo.h
+++ b/src/mongo/util/processinfo.h
@@ -92,6 +92,11 @@ namespace mongo {
         bool hasNumaEnabled() const { return sysInfo().hasNuma; }
 
         /**
+         * Determine if file zeroing is necessary for newly allocated data files.
+         */
+        static bool isDataFileZeroingNeeded() { return systemInfo->fileZeroNeeded;  }
+
+        /**
          * Get extra system stats
          */
         void appendSystemDetails( BSONObjBuilder& details ) const {
@@ -145,12 +150,19 @@ namespace mongo {
             string cpuArch;
             bool hasNuma;
             BSONObj _extraStats;
+
+            // This is an OS specific value, which determines whether files should be zero-filled
+            // at allocation time in order to avoid Microsoft KB 2731284.
+            //
+            bool fileZeroNeeded;
+
             SystemInfo() :
                     addrSize( 0 ),
                     memSize( 0 ),
                     numCores( 0 ),
                     pageSize( 0 ),
-                    hasNuma( false ) { 
+                    hasNuma( false ),
+                    fileZeroNeeded (false) { 
                 // populate SystemInfo during construction
                 collectSystemInfo();
             }
diff --git a/src/mongo/util/processinfo_win32.cpp b/src/mongo/util/processinfo_win32.cpp
index 3f42eb12698..d6f88e88a59 100644
--- a/src/mongo/util/processinfo_win32.cpp
+++ b/src/mongo/util/processinfo_win32.cpp
@@ -100,7 +100,7 @@ namespace mongo {
     void ProcessInfo::SystemInfo::collectSystemInfo() {
         BSONObjBuilder bExtra;
         stringstream verstr;
-        OSVERSIONINFOEX osvi;   // os version 
+        OSVERSIONINFOEX osvi;   // os version
         MEMORYSTATUSEX mse;     // memory stats
         SYSTEM_INFO ntsysinfo;  //system stats
 
@@ -142,6 +142,15 @@ namespace mongo {
                             osName += "Windows 7";
                         else
                             osName += "Windows Server 2008 R2";
+
+                        // Windows 6.1 is either Windows 7 or Windows 2008 R2. There is no SP2 for
+                        // either of these two operating systems, but the check will hold if one
+                        // were released. This code assumes that SP2 will include fix for 
+                        // http://support.microsoft.com/kb/2731284.
+                        //
+                        if ((osvi.wServicePackMajor >= 0) && (osvi.wServicePackMajor < 2)) {
+                            fileZeroNeeded = true;
+                        }
                         break;
                     case 0:
                         if ( osvi.wProductType == VER_NT_WORKSTATION )