avoid macos bulkstat vlru when no non-dead vnodes exist

if we can't find a candidate to be the vlru item to manipulate past,
simply don't do the vlru update

FIXES 126868

Change-Id: I5c053d1934b0787ab7f2021c70a776e54208d345
Reviewed-on: http://gerrit.openafs.org/1690
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>

diff --git a/src/afs/VNOPS/afs_vnop_lookup.c b/src/afs/VNOPS/afs_vnop_lookup.c
index c4d2a11..4846558 100644 (file)
--- a/src/afs/VNOPS/afs_vnop_lookup.c
+++ b/src/afs/VNOPS/afs_vnop_lookup.c
@@ -647,7 +647,10 @@ afs_DoBulkStat(struct vcache *adp, long dirCookie, struct vrequest *areqp)
 {
     int nentries;              /* # of entries to prefetch */
     int nskip;                 /* # of slots in the LRU queue to skip */
+    int novlru = 0;             /* Currently Darwin-only but can be used
+                                  globally if needed */
 #ifdef AFS_DARWIN80_ENV
+    int npasses = 0;
     struct vnode *lruvp;
 #endif
     struct vcache *lruvcp;     /* vcache ptr of our goal pos in LRU queue */
@@ -974,6 +977,7 @@ afs_DoBulkStat(struct vcache *adp, long dirCookie, struct vrequest *areqp)
   reskip:
     nskip = afs_cacheStats / 2;        /* preserved fraction of the cache */
     ObtainReadLock(&afs_xvcache);
+ reskip2:
     if (QEmpty(&VLRU)) {
        /* actually a serious error, probably should panic. Probably will 
         * panic soon, oh well. */
@@ -1008,18 +1012,31 @@ afs_DoBulkStat(struct vcache *adp, long dirCookie, struct vrequest *areqp)
      */
     retry = 0;
 #ifdef AFS_DARWIN80_ENV
-    lruvp = AFSTOV(lruvcp);
-    if (vnode_get(lruvp))       /* this bumps ref count */
-       retry = 1;
-    else if (vnode_ref(lruvp)) {
-       AFS_GUNLOCK();
-       /* AFSTOV(lruvcp) may be NULL */
-       vnode_put(lruvp);
-       AFS_GLOCK();
-       retry = 1;
+    if ((lruvcp->f.states & CDeadVnode)) {
+       if (npasses == 0) {
+           nskip = 1;
+           npasses++;
+           goto reskip2;
+       } else {
+           afs_warn("Can't find non-dead vnode in VLRU\n");
+           novlru = 1;
+       }
+    }
+    if (!novlru) {
+       lruvp = AFSTOV(lruvcp);
+       if (vnode_get(lruvp))       /* this bumps ref count */
+           retry = 1;
+       else if (vnode_ref(lruvp)) {
+           AFS_GUNLOCK();
+           /* AFSTOV(lruvcp) may be NULL */
+           vnode_put(lruvp);
+           AFS_GLOCK();
+           retry = 1;
+       }
     }
 #else
-    osi_vnhold(lruvcp, &retry);
+    if (novlru)
+       osi_vnhold(lruvcp, &retry);
 #endif
     ReleaseReadLock(&afs_xvcache);     /* could be read lock */
     if (retry)
@@ -1085,36 +1102,38 @@ afs_DoBulkStat(struct vcache *adp, long dirCookie, struct vrequest *areqp)
            *tvcp->mvid = dotdot;
        }
 
-       ObtainWriteLock(&afs_xvcache, 132);
-       if ((VLRU.next->prev != &VLRU) || (VLRU.prev->next != &VLRU)) {
-           refpanic("Bulkstat VLRU inconsistent2");
-       }
-       if ((QNext(QPrev(&tvcp->vlruq)) != &tvcp->vlruq)
-           || (QPrev(QNext(&tvcp->vlruq)) != &tvcp->vlruq)) {
-           refpanic("Bulkstat VLRU inconsistent4");
-       }
-       if ((QNext(QPrev(&lruvcp->vlruq)) != &lruvcp->vlruq)
-           || (QPrev(QNext(&lruvcp->vlruq)) != &lruvcp->vlruq)) {
-           refpanic("Bulkstat VLRU inconsistent5");
-       }
-
-       if (tvcp != lruvcp) {   /* if they are == don't move it, don't corrupt vlru */
-           QRemove(&tvcp->vlruq);
-           QAdd(&lruvcp->vlruq, &tvcp->vlruq);
-       }
-
-       if ((VLRU.next->prev != &VLRU) || (VLRU.prev->next != &VLRU)) {
-           refpanic("Bulkstat VLRU inconsistent3");
-       }
-       if ((QNext(QPrev(&tvcp->vlruq)) != &tvcp->vlruq)
-           || (QPrev(QNext(&tvcp->vlruq)) != &tvcp->vlruq)) {
-           refpanic("Bulkstat VLRU inconsistent5");
-       }
-       if ((QNext(QPrev(&lruvcp->vlruq)) != &lruvcp->vlruq)
-           || (QPrev(QNext(&lruvcp->vlruq)) != &lruvcp->vlruq)) {
-           refpanic("Bulkstat VLRU inconsistent6");
+       if (!novlru) {
+           ObtainWriteLock(&afs_xvcache, 132);
+           if ((VLRU.next->prev != &VLRU) || (VLRU.prev->next != &VLRU)) {
+               refpanic("Bulkstat VLRU inconsistent2");
+           }
+           if ((QNext(QPrev(&tvcp->vlruq)) != &tvcp->vlruq)
+               || (QPrev(QNext(&tvcp->vlruq)) != &tvcp->vlruq)) {
+               refpanic("Bulkstat VLRU inconsistent4");
+           }
+           if ((QNext(QPrev(&lruvcp->vlruq)) != &lruvcp->vlruq)
+               || (QPrev(QNext(&lruvcp->vlruq)) != &lruvcp->vlruq)) {
+               refpanic("Bulkstat VLRU inconsistent5");
+           }
+           
+           if (tvcp != lruvcp) {       /* if they are == don't move it, don't corrupt vlru */
+               QRemove(&tvcp->vlruq);
+               QAdd(&lruvcp->vlruq, &tvcp->vlruq);
+           }
+           
+           if ((VLRU.next->prev != &VLRU) || (VLRU.prev->next != &VLRU)) {
+               refpanic("Bulkstat VLRU inconsistent3");
+           }
+           if ((QNext(QPrev(&tvcp->vlruq)) != &tvcp->vlruq)
+               || (QPrev(QNext(&tvcp->vlruq)) != &tvcp->vlruq)) {
+               refpanic("Bulkstat VLRU inconsistent5");
+           }
+           if ((QNext(QPrev(&lruvcp->vlruq)) != &lruvcp->vlruq)
+               || (QPrev(QNext(&lruvcp->vlruq)) != &lruvcp->vlruq)) {
+               refpanic("Bulkstat VLRU inconsistent6");
+           }
+           ReleaseWriteLock(&afs_xvcache);
        }
-       ReleaseWriteLock(&afs_xvcache);
 
        ObtainWriteLock(&afs_xcbhash, 494);
 
@@ -1208,14 +1227,16 @@ afs_DoBulkStat(struct vcache *adp, long dirCookie, struct vrequest *areqp)
     }                          /* for all files we got back */
 
     /* finally return the pointer into the LRU queue */
+    if (!novlru) {
 #ifdef AFS_DARWIN80_ENV
-    AFS_GUNLOCK();
-    vnode_put(lruvp);
-    vnode_rele(lruvp);
-    AFS_GLOCK();
+       AFS_GUNLOCK();
+       vnode_put(lruvp);
+       vnode_rele(lruvp);
+       AFS_GLOCK();
 #else
-    afs_PutVCache(lruvcp);
+       afs_PutVCache(lruvcp);
 #endif
+    }
 
   done:
     /* Be sure to turn off the CBulkFetching flags */