From: Derrick Brashear <shadow@dementix.org>
Date: Mon, 15 Aug 2011 16:17:06 +0000 (-0400)
Subject: macos: fix race in afs_root
X-Git-Tag: openafs-devel-1_7_1~131
X-Git-Url: https://git.openafs.org/?p=openafs.git;a=commitdiff_plain;h=ad6e19331e4f3ec6566dc224f1e1c943a69c62bb

macos: fix race in afs_root

same race on PutVCache in afs_root as we had on other platforms,
for instance FreeBSD. use a local variable instead to avoid the race.
additionally, make sure we end up with the root flagged VROOT.

Change-Id: I45ac36f12565320576070fd1c6d1f99ac6db8a63
Reviewed-on: http://gerrit.openafs.org/5278
Tested-by: Derrick Brashear <shadow@dementix.org>
Reviewed-by: Derrick Brashear <shadow@dementix.org>
---

diff --git a/src/afs/DARWIN/osi_vfsops.c b/src/afs/DARWIN/osi_vfsops.c
index 919a3d0..d0efb8c 100644
--- a/src/afs/DARWIN/osi_vfsops.c
+++ b/src/afs/DARWIN/osi_vfsops.c
@@ -222,9 +222,10 @@ afs_root(struct mount *mp, struct vnode **vpp)
     int error;
     struct vrequest treq;
     struct vcache *tvp = 0;
+    struct vcache *gvp;
+    int needref=0;
 #ifdef AFS_DARWIN80_ENV
     struct ucred *cr = vfs_context_ucred(ctx);
-    int needref=0;
 #else
     struct proc *p = current_proc();
     struct ucred _cr;
@@ -236,13 +237,13 @@ afs_root(struct mount *mp, struct vnode **vpp)
 #endif
     AFS_GLOCK();
     AFS_STATCNT(afs_root);
+
+again:
     if (mdata == NULL && afs_globalVp
 	&& (afs_globalVp->f.states & CStatd)) {
 	tvp = afs_globalVp;
 	error = 0;
-#ifdef AFS_DARWIN80_ENV
         needref=1;
-#endif
     } else if (mdata == (qaddr_t) - 1) {
 	error = ENOENT;
     } else {
@@ -266,36 +267,46 @@ afs_root(struct mount *mp, struct vnode **vpp)
 	    /* we really want this to stay around */
 	    if (tvp) {
 		if (mdata == NULL) {
-		    if (afs_globalVp) {
-			afs_PutVCache(afs_globalVp);
-			afs_globalVp = NULL;
-		    }
+		    gvp = afs_globalVp;
 		    afs_globalVp = tvp;
-#ifdef AFS_DARWIN80_ENV
+		    if (gvp) {
+			afs_PutVCache(gvp);
+			if (tvp != afs_globalVp) {
+			    /* someone else got there before us! */
+			    afs_PutVCache(tvp);
+			    tvp = 0;
+			    goto again;
+			}
+		    }
                     needref=1;
-#endif
                 }
 	    } else
 		error = ENOENT;
 	}
     }
     if (tvp) {
-#ifndef AFS_DARWIN80_ENV /* DARWIN80 caller does not need a usecount reference */
+#ifndef AFS_DARWIN80_ENV /* KPI callers don't need a usecount reference */
 	osi_vnhold(tvp, 0);
 	AFS_GUNLOCK();
 	vn_lock(AFSTOV(tvp), LK_EXCLUSIVE | LK_RETRY, p);
 	AFS_GLOCK();
 #endif
+
+        if (needref)
 #ifdef AFS_DARWIN80_ENV
-        if (needref) /* this iocount is for the caller. the initial iocount
-                        is for the eventual afs_PutVCache. for mdata != null,
-                        there will not be a PutVCache, so the caller gets the
-                        initial (from GetVCache or finalizevnode) iocount*/
-           vnode_get(AFSTOV(tvp));
+	    /* This iocount is for the caller. the initial iocount
+	     * is for the eventual afs_PutVCache. for mdata != null,
+	     * there will not be a PutVCache, so the caller gets the
+	     * initial (from GetVCache or finalizevnode) iocount
+	     */
+	    vnode_get(AFSTOV(tvp));
+#else
+	    ;
 #endif
-	if (mdata == NULL) {
+
+	if (mdata == NULL)
 	    afs_globalVFS = mp;
-	}
+
 	*vpp = AFSTOV(tvp);
 #ifndef AFS_DARWIN80_ENV 
 	AFSTOV(tvp)->v_flag |= VROOT;
diff --git a/src/afs/DARWIN/osi_vnodeops.c b/src/afs/DARWIN/osi_vnodeops.c
index 108474b..1d8a163 100644
--- a/src/afs/DARWIN/osi_vnodeops.c
+++ b/src/afs/DARWIN/osi_vnodeops.c
@@ -2163,10 +2163,7 @@ afs_darwin_finalizevnode(struct vcache *avc, struct vnode *dvp,
     }
     ovp = AFSTOV(avc);
 
-    /* if the type changed, we still need to do a fixup, for bulkstat */
-    if (!isroot && (vnode_vtype(ovp) == avc->f.m.Type &&
-		    !(avc->f.states & CDeadVnode) && vnode_vtype(ovp) != VNON))
-    {
+    if (!(avc->f.states & CDeadVnode) && vnode_vtype(ovp) != VNON) {
 	AFS_GUNLOCK();
 #if 0 /* unsupported */
         if (dvp && cnp)
diff --git a/src/afs/afs_vcache.c b/src/afs/afs_vcache.c
index aac212b..d93ed55 100644
--- a/src/afs/afs_vcache.c
+++ b/src/afs/afs_vcache.c
@@ -1526,12 +1526,8 @@ afs_ProcessFS(struct vcache *avc,
 	}
     }
 #ifdef AFS_DARWIN80_ENV
-    if (fixup) {
-	/* perform type correction on underlying vnode */
-	afs_darwin_finalizevnode(avc, NULL, NULL, 0, 1);
-	/* re-acquire the usecount that finalizevnode disposed of */
-	vnode_ref(AFSTOV(avc));
-    }
+    if (fixup)
+	printf("found mistyped vnode!\n");
 #endif
     avc->f.anyAccess = astat->AnonymousAccess;
 #ifdef badidea