Avoid panic on shutdown with memcache and INVARIANTS

When running with memcache, the filesystem cache is not initialized,
so the file-local struct vnode *volumeVnode is never set to non-NULL.
However, shutdown_cache() unconditionally calls vrele(volumeVnode),
which triggers a KASSERT that the argument to vrele() is non-NULL.
For certain kernel configurations, this results in a panic.
Change this so that vrele() is only conditionally called if the
volumeVnode is non-NULL.

Change-Id: I80235f0d45ae11f26e9a09854bb34439f89bbb40
Reviewed-on: http://gerrit.openafs.org/1576
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>

diff --git a/src/afs/afs_init.c b/src/afs/afs_init.c
index 374be7c..76d294d 100644 (file)
--- a/src/afs/afs_init.c
+++ b/src/afs/afs_init.c
@@ -694,8 +694,11 @@ shutdown_cache(void)
        pag_epoch = 0;
        pagCounter = 0;
 #if defined(AFS_XBSD_ENV)
-       vrele(volumeVnode);     /* let it go, finally. */
-       volumeVnode = NULL;
+       /* memcache never sets this, so don't panic on shutdown */
+       if (volumeVnode != NULL) {
+           vrele(volumeVnode); /* let it go, finally. */
+           volumeVnode = NULL;
+       }
        if (cacheDev.held_vnode) {
            vrele(cacheDev.held_vnode);
            cacheDev.held_vnode = NULL;