From 54a3c85ae44aaaac9dd933893d975199b3cdca70 Mon Sep 17 00:00:00 2001
From: Jeffrey Altman <jaltman@secure-endpoints.com>
Date: Sat, 21 Feb 2009 04:19:23 +0000
Subject: [PATCH] windows-rename-cross-dir-invalid-handle-20090220

LICENSE MIT

Problems with the cm_Rename() functions:

 * when a rename occurs across directories, the file server allocates
   a new vnode which in turn alters the FID.  Since the new FID and
   potentially version number is unknown to the client, it is not
   possible to update the target directory with the new name and
   FID thereby avoiding reading the directory from the file server.

 * when the old vnode is removed, the callback is broken but the
   client did not discard the cm_scache_t object

In order to optimize the client cache AFS requires a RXAFS_RenameEx
rpc that is equivalent to the current RPC but returns the new FID
and status.  This would permit the cache manager to relabel the
data buffers and cm_scache_t that are known to contain valid data.
---
 src/WINNT/afsd/cm_vnodeops.c | 62 +++++++++++++++++++++++-------------
 1 file changed, 40 insertions(+), 22 deletions(-)

diff --git a/src/WINNT/afsd/cm_vnodeops.c b/src/WINNT/afsd/cm_vnodeops.c
index 81229786a..c16a88fa4 100644
--- a/src/WINNT/afsd/cm_vnodeops.c
+++ b/src/WINNT/afsd/cm_vnodeops.c
@@ -3366,9 +3366,6 @@ long cm_Rename(cm_scache_t *oldDscp, fschar_t *oldNamep, clientchar_t *cOldNamep
     } else {
         code = 0;
     }
-    cm_ReleaseSCache(oldScp);
-    oldScp = NULL;
-
     if (code) 
         goto done;
 
@@ -3549,31 +3546,28 @@ long cm_Rename(cm_scache_t *oldDscp, fschar_t *oldNamep, clientchar_t *cOldNamep
                        userp, CM_MERGEFLAG_DIROP);
     lock_ReleaseWrite(&oldDscp->rw);
 
-    if (code == 0) {
-        if (cm_CheckDirOpForSingleChange(&oldDirOp)) {
-
+    if (code == 0 && cm_CheckDirOpForSingleChange(&oldDirOp)) {
 #ifdef USE_BPLUS
-            diropCode = cm_BPlusDirLookup(&oldDirOp, cOldNamep, &fileFid);
-            if (diropCode == CM_ERROR_INEXACT_MATCH)
-                diropCode = 0;
-            else if (diropCode == EINVAL)
+        diropCode = cm_BPlusDirLookup(&oldDirOp, cOldNamep, &fileFid);
+        if (diropCode == CM_ERROR_INEXACT_MATCH)
+            diropCode = 0;
+        else if (diropCode == EINVAL)
 #endif
-                diropCode = cm_DirLookup(&oldDirOp, oldNamep, &fileFid);
+            diropCode = cm_DirLookup(&oldDirOp, oldNamep, &fileFid);
 
-            if (diropCode == 0) {
-                if (oneDir) {
-                    diropCode = cm_DirCreateEntry(&oldDirOp, newNamep, &fileFid);
-#ifdef USE_BPLUS
-                    cm_BPlusDirCreateEntry(&oldDirOp, cNewNamep, &fileFid);
+        if (diropCode == 0) {
+            if (oneDir) {
+                diropCode = cm_DirCreateEntry(&oldDirOp, newNamep, &fileFid);
+#ifdef USE_BPLUS        
+                cm_BPlusDirCreateEntry(&oldDirOp, cNewNamep, &fileFid);
 #endif
-                }
+            }
                 
-                if (diropCode == 0) { 
-                    diropCode = cm_DirDeleteEntry(&oldDirOp, oldNamep);
+            if (diropCode == 0) { 
+                diropCode = cm_DirDeleteEntry(&oldDirOp, oldNamep);
 #ifdef USE_BPLUS
-                    cm_BPlusDirDeleteEntry(&oldDirOp, cOldNamep);
-#endif
-                }
+                cm_BPlusDirDeleteEntry(&oldDirOp, cOldNamep);
+#endif  
             }
         }
     }
@@ -3592,6 +3586,17 @@ long cm_Rename(cm_scache_t *oldDscp, fschar_t *oldNamep, clientchar_t *cOldNamep
                             userp, CM_MERGEFLAG_DIROP);
         lock_ReleaseWrite(&newDscp->rw);
 
+#if 0 
+        /* 
+         * The following optimization does not work.  
+         * When the file server processed a RXAFS_Rename() request the 
+         * FID of the object being moved between directories is not 
+         * preserved.  The client does not know the new FID nor the 
+         * version number of the target.  Not only can we not create
+         * the directory entry in the new directory, but we can't 
+         * preserve the cached data for the file.  It must be re-read
+         * from the file server.  - jaltman, 2009/02/20
+         */
         if (code == 0) {
             /* we only make the local change if we successfully made
                the change in the old directory AND there was only one
@@ -3603,10 +3608,23 @@ long cm_Rename(cm_scache_t *oldDscp, fschar_t *oldNamep, clientchar_t *cOldNamep
 #endif
             }
         }
+#endif /* 0 */
         cm_EndDirOp(&newDirOp);
     }
 
+    /* 
+     * After the rename the file server has invalidated the callbacks
+     * on the file that was moved nor do we have a directory reference 
+     * to it anymore.
+     */
+    lock_ObtainWrite(&oldScp->rw);
+    cm_DiscardSCache(oldScp);
+    lock_ReleaseWrite(&oldScp->rw);
+
   done:
+    if (oldScp)
+        cm_ReleaseSCache(oldScp);
+
     if (free_oldNamep)
         free(oldNamep);
 
-- 
2.39.5