From aed1493e906921b6b0b786286c01ada9d0d6dede Mon Sep 17 00:00:00 2001
From: Olga Kornievskaia <aglo@citi.umich.edu>
Date: Wed, 7 Dec 2011 18:10:09 -0500
Subject: [PATCH] adding writethru mount option

for large writes it is beneficial to turnoff write buffering and allow
large write buffer sizes than 1M (for win 7).
---
 sys/nfs41_driver.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/sys/nfs41_driver.c b/sys/nfs41_driver.c
index b776120..24e2658 100644
--- a/sys/nfs41_driver.c
+++ b/sys/nfs41_driver.c
@@ -318,6 +318,7 @@ typedef struct _NFS41_MOUNT_CONFIG {
     DWORD ReadSize;
     DWORD WriteSize;
     BOOLEAN ReadOnly;
+    BOOLEAN write_thru;
     WCHAR srv_buffer[SERVER_NAME_BUFFER_SIZE];
     UNICODE_STRING SrvName;
     WCHAR mntpt_buffer[MAX_PATH];
@@ -350,6 +351,7 @@ typedef struct _NFS41_V_NET_ROOT_EXTENSION {
     LONG                    FsAttrsLen;
     DWORD                   sec_flavor;
     BOOLEAN                 read_only;
+    BOOLEAN                 write_thru;
 #define STORE_MOUNT_SEC_CONTEXT
 #ifdef STORE_MOUNT_SEC_CONTEXT
     SECURITY_CLIENT_CONTEXT mount_sec_ctx;
@@ -2409,6 +2411,7 @@ void nfs41_MountConfig_InitDefaults(
     Config->ReadSize = MOUNT_CONFIG_RW_SIZE_DEFAULT;
     Config->WriteSize = MOUNT_CONFIG_RW_SIZE_DEFAULT;
     Config->ReadOnly = FALSE;
+    Config->write_thru = FALSE;
     Config->SrvName.Length = 0;
     Config->SrvName.MaximumLength = SERVER_NAME_BUFFER_SIZE;
     Config->SrvName.Buffer = Config->srv_buffer;
@@ -2500,6 +2503,11 @@ NTSTATUS nfs41_MountConfig_ParseOptions(
             status = nfs41_MountConfig_ParseBoolean(Option, &usValue,
                 &Config->ReadOnly);
         }
+        else if (wcsncmp(L"writethru", Name, NameLen) == 0)
+        {
+            status = nfs41_MountConfig_ParseBoolean(Option, &usValue,
+                &Config->write_thru);
+        }
         else if (wcsncmp(L"rsize", Name, NameLen) == 0)
         {
             status = nfs41_MountConfig_ParseDword(Option, &usValue,
@@ -2698,7 +2706,8 @@ NTSTATUS nfs41_CreateVNetRoot(
             &Config);
         if (status != STATUS_SUCCESS)
             goto out;
-        pVNetRootContext->read_only = Config.ReadOnly; 
+        pVNetRootContext->read_only = Config.ReadOnly;
+        pVNetRootContext->write_thru = Config.write_thru;
     } else {
         /* use the SRV_CALL name (without leading \) as the hostname */
         Config.SrvName.Buffer = pSrvCall->pSrvCallName->Buffer + 1;
@@ -3335,7 +3344,8 @@ NTSTATUS nfs41_Create(
         // the file was opened read-only.
         if (/*(params.DesiredAccess & FILE_READ_DATA) && */
                 (params.DesiredAccess & FILE_WRITE_DATA || 
-                params.DesiredAccess & FILE_APPEND_DATA))
+                params.DesiredAccess & FILE_APPEND_DATA) && 
+                !pVNetRootContext->write_thru)
             SrvOpen->BufferingFlags |= 
                 (FCB_STATE_WRITECACHING_ENABLED | FCB_STATE_WRITEBUFFERING_ENABLED);
 #endif
@@ -5084,6 +5094,7 @@ NTSTATUS nfs41_Write (
                 LOWIO_READWRITEFLAG_PAGING_IO) && 
                 (SrvOpen->DesiredAccess & FILE_WRITE_DATA) &&
                 (SrvOpen->DesiredAccess & FILE_READ_DATA) &&
+                !pVNetRootContext->write_thru &&
                 !(SrvOpen->BufferingFlags & 
                 (FCB_STATE_WRITEBUFFERING_ENABLED | FCB_STATE_WRITECACHING_ENABLED)))
             enable_caching(SrvOpen);