From fd7856fa5d60775aae763350317eea4c14964812 Mon Sep 17 00:00:00 2001
From: Jeffrey Altman <jaltman@secure-endpoints.com>
Date: Mon, 10 Dec 2007 20:35:06 +0000
Subject: [PATCH] DEVEL15-windows-buffers-20071210

LICENSE MIT

after removing cm_buf_t objects from the hash tables, clear the HT list
pointers to make debugging easier.

when modifying data version values in buf_ForceDataVersion() grab a
read lock on buf_globalLock instead of a write lock.  A write lock is
only required if the hash table linked lists are being modified.
The dataVersion itself is protected by the cm_scache_t mx mutex being
held.


(cherry picked from commit ef5e9a4dd7a4977d7d9f41266f2a0c491720e387)
---
 src/WINNT/afsd/cm_buf.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/src/WINNT/afsd/cm_buf.c b/src/WINNT/afsd/cm_buf.c
index 52658f18e4..dc7b4aefc9 100644
--- a/src/WINNT/afsd/cm_buf.c
+++ b/src/WINNT/afsd/cm_buf.c
@@ -700,19 +700,23 @@ void buf_Recycle(cm_buf_t *bp)
         i = BUF_HASH(&bp->fid, &bp->offset);
         lbpp = &(cm_data.buf_scacheHashTablepp[i]);
         for(tbp = *lbpp; tbp; lbpp = &tbp->hashp, tbp = *lbpp) {
-            if (tbp == bp) break;
+            if (tbp == bp) 
+                break;
         }
 
         /* we better find it */
         osi_assertx(tbp != NULL, "buf_Recycle: hash table screwup");
 
         *lbpp = bp->hashp;	/* hash out */
+        bp->hashp = NULL;
 
         /* Remove from file hash */
 
         i = BUF_FILEHASH(&bp->fid);
         prevBp = bp->fileHashBackp;
+        bp->fileHashBackp = NULL;
         nextBp = bp->fileHashp;
+        bp->fileHashp = NULL;
         if (prevBp)
             prevBp->fileHashp = nextBp;
         else
@@ -1560,7 +1564,7 @@ long buf_ForceDataVersion(cm_scache_t * scp, afs_uint64 fromVersion, afs_uint64
 
     i = BUF_FILEHASH(&scp->fid);
 
-    lock_ObtainWrite(&buf_globalLock);
+    lock_ObtainRead(&buf_globalLock);
 
     for (bp = cm_data.buf_fileHashTablepp[i]; bp; bp = bp->fileHashp) {
         if (cm_FidCmp(&bp->fid, &scp->fid) == 0) {
@@ -1570,7 +1574,7 @@ long buf_ForceDataVersion(cm_scache_t * scp, afs_uint64 fromVersion, afs_uint64
             }
         }
     }
-    lock_ReleaseWrite(&buf_globalLock);
+    lock_ReleaseRead(&buf_globalLock);
 
     if (found)
         return 0;