Module Name: src
Committed By: hannken
Date: Tue Aug 18 09:44:07 UTC 2020
Modified Files:
src/sys/fs/union: union.h union_subr.c union_vnops.c
Log Message:
Operation union_readdirhook() stores the lower directory as un_uppervp.
This breaks the assumption that un_uppervp->v_mount is the upper mount.
Fix by storing the directory as un_lowervp and adapt union_readdir().
Should fix PR kern/55552: panic with union mount
To generate a diff of this commit:
cvs rdiff -u -r1.29 -r1.30 src/sys/fs/union/union.h
cvs rdiff -u -r1.78 -r1.79 src/sys/fs/union/union_subr.c
cvs rdiff -u -r1.73 -r1.74 src/sys/fs/union/union_vnops.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/fs/union/union.h
diff -u src/sys/fs/union/union.h:1.29 src/sys/fs/union/union.h:1.30
--- src/sys/fs/union/union.h:1.29 Mon Jul 17 09:22:36 2017
+++ src/sys/fs/union/union.h Tue Aug 18 09:44:07 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: union.h,v 1.29 2017/07/17 09:22:36 hannken Exp $ */
+/* $NetBSD: union.h,v 1.30 2020/08/18 09:44:07 hannken Exp $ */
/*
* Copyright (c) 1994 The Regents of the University of California.
@@ -130,6 +130,7 @@ struct union_node {
char *un_path; /* v: saved component name */
int un_openl; /* v: # of opens on lowervp */
unsigned int un_cflags; /* c: cache flags */
+ bool un_hooknode; /* :: from union_readdirhook */
struct vnode **un_dircache; /* v: cached union stack */
off_t un_uppersz; /* l: size of upper object */
off_t un_lowersz; /* l: size of lower object */
Index: src/sys/fs/union/union_subr.c
diff -u src/sys/fs/union/union_subr.c:1.78 src/sys/fs/union/union_subr.c:1.79
--- src/sys/fs/union/union_subr.c:1.78 Sun Feb 23 15:46:41 2020
+++ src/sys/fs/union/union_subr.c Tue Aug 18 09:44:07 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: union_subr.c,v 1.78 2020/02/23 15:46:41 ad Exp $ */
+/* $NetBSD: union_subr.c,v 1.79 2020/08/18 09:44:07 hannken Exp $ */
/*
* Copyright (c) 1994
@@ -72,7 +72,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: union_subr.c,v 1.78 2020/02/23 15:46:41 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: union_subr.c,v 1.79 2020/08/18 09:44:07 hannken Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@@ -480,6 +480,7 @@ found:
un->un_dircache = 0;
un->un_openl = 0;
un->un_cflags = 0;
+ un->un_hooknode = false;
un->un_uppersz = VNOVAL;
un->un_lowersz = VNOVAL;
@@ -1067,7 +1068,7 @@ union_dircache(struct vnode *vp, struct
} else {
vpp = dircache;
do {
- if (*vpp++ == VTOUNION(vp)->un_uppervp)
+ if (*vpp++ == VTOUNION(vp)->un_lowervp)
break;
} while (*vpp != NULLVP);
}
@@ -1076,10 +1077,12 @@ union_dircache(struct vnode *vp, struct
goto out;
vref(*vpp);
- error = union_allocvp(&nvp, vp->v_mount, NULLVP, NULLVP, 0, *vpp, NULLVP, 0);
+ error = union_allocvp(&nvp, vp->v_mount, NULLVP, NULLVP, 0,
+ NULLVP, *vpp, 0);
if (!error) {
vn_lock(nvp, LK_EXCLUSIVE | LK_RETRY);
VTOUNION(vp)->un_dircache = 0;
+ VTOUNION(nvp)->un_hooknode = true;
VTOUNION(nvp)->un_dircache = dircache;
}
Index: src/sys/fs/union/union_vnops.c
diff -u src/sys/fs/union/union_vnops.c:1.73 src/sys/fs/union/union_vnops.c:1.74
--- src/sys/fs/union/union_vnops.c:1.73 Sat May 16 18:31:50 2020
+++ src/sys/fs/union/union_vnops.c Tue Aug 18 09:44:07 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: union_vnops.c,v 1.73 2020/05/16 18:31:50 christos Exp $ */
+/* $NetBSD: union_vnops.c,v 1.74 2020/08/18 09:44:07 hannken Exp $ */
/*
* Copyright (c) 1992, 1993, 1994, 1995
@@ -72,7 +72,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: union_vnops.c,v 1.73 2020/05/16 18:31:50 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: union_vnops.c,v 1.74 2020/08/18 09:44:07 hannken Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@@ -1493,13 +1493,29 @@ union_readdir(void *v)
int a_ncookies;
} */ *ap = v;
struct union_node *un = VTOUNION(ap->a_vp);
- struct vnode *uvp = un->un_uppervp;
+ struct vnode *vp;
+ int dolock, error;
- if (uvp == NULLVP)
- return (0);
+ if (un->un_hooknode) {
+ KASSERT(un->un_uppervp == NULLVP);
+ KASSERT(un->un_lowervp != NULLVP);
+ vp = un->un_lowervp;
+ dolock = 1;
+ } else {
+ vp = un->un_uppervp;
+ dolock = 0;
+ }
+ if (vp == NULLVP)
+ return 0;
- ap->a_vp = uvp;
- return (VCALL(uvp, VOFFSET(vop_readdir), ap));
+ if (dolock)
+ vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
+ ap->a_vp = vp;
+ error = VCALL(vp, VOFFSET(vop_readdir), ap);
+ if (dolock)
+ VOP_UNLOCK(vp);
+
+ return error;
}
int
