[src/trunk]: src/sys Change forced unmount to revert open device vnodes to an...

[hannken <hannken%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/13863d9730ed
branches:  trunk
changeset: 355906:13863d9730ed
user:      hannken <hannken%NetBSD.org@localhost>
date:      Mon Aug 21 09:00:21 2017 +0000

description:
Change forced unmount to revert open device vnodes to anonymous devices.

diffstat:

 sys/kern/vfs_mount.c |  13 +++++++--
 sys/kern/vfs_vnode.c |  71 ++++++++++++++++++++++++++++++++++++++++++++++++++-
 sys/sys/vnode_impl.h |   3 +-
 3 files changed, 81 insertions(+), 6 deletions(-)

diffs (152 lines):

diff -r 3687fe4ce6a6 -r 13863d9730ed sys/kern/vfs_mount.c
--- a/sys/kern/vfs_mount.c      Mon Aug 21 08:56:45 2017 +0000
+++ b/sys/kern/vfs_mount.c      Mon Aug 21 09:00:21 2017 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vfs_mount.c,v 1.66 2017/06/04 08:05:42 hannken Exp $   */
+/*     $NetBSD: vfs_mount.c,v 1.67 2017/08/21 09:00:21 hannken Exp $   */
 
 /*-
  * Copyright (c) 1997-2011 The NetBSD Foundation, Inc.
@@ -67,7 +67,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_mount.c,v 1.66 2017/06/04 08:05:42 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_mount.c,v 1.67 2017/08/21 09:00:21 hannken Exp $");
 
 #include <sys/param.h>
 #include <sys/kernel.h>
@@ -558,9 +558,16 @@
                return 0;
        /*
         * If FORCECLOSE is set, forcibly close the vnode.
+        * For block or character devices, revert to an
+        * anonymous device.  For all other files, just
+        * kill them.
         */
        if (flags & FORCECLOSE) {
-               vgone(vp);
+               if (vp->v_usecount > 1 &&
+                   (vp->v_type == VBLK || vp->v_type == VCHR))
+                       vcache_make_anon(vp);
+               else
+                       vgone(vp);
                return 0;
        }
        vrele(vp);
diff -r 3687fe4ce6a6 -r 13863d9730ed sys/kern/vfs_vnode.c
--- a/sys/kern/vfs_vnode.c      Mon Aug 21 08:56:45 2017 +0000
+++ b/sys/kern/vfs_vnode.c      Mon Aug 21 09:00:21 2017 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vfs_vnode.c,v 1.97 2017/08/21 08:56:45 hannken Exp $   */
+/*     $NetBSD: vfs_vnode.c,v 1.98 2017/08/21 09:00:21 hannken Exp $   */
 
 /*-
  * Copyright (c) 1997-2011 The NetBSD Foundation, Inc.
@@ -156,7 +156,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_vnode.c,v 1.97 2017/08/21 08:56:45 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_vnode.c,v 1.98 2017/08/21 09:00:21 hannken Exp $");
 
 #include <sys/param.h>
 #include <sys/kernel.h>
@@ -225,6 +225,7 @@
 /* Routines having to do with the management of the vnode table. */
 extern struct mount    *dead_rootmount;
 extern int             (**dead_vnodeop_p)(void *);
+extern int             (**spec_vnodeop_p)(void *);
 extern struct vfsops   dead_vfsops;
 
 /* Vnode state operations and diagnostics. */
@@ -1650,6 +1651,72 @@
 }
 
 /*
+ * Disassociate the underlying file system from an open device vnode
+ * and make it anonymous.
+ *
+ * Vnode unlocked on entry, drops a reference to the vnode.
+ */
+void
+vcache_make_anon(vnode_t *vp)
+{
+       vnode_impl_t *vip = VNODE_TO_VIMPL(vp);
+       uint32_t hash;
+       bool recycle;
+
+       KASSERT(vp->v_type == VBLK || vp->v_type == VCHR);
+       KASSERT((vp->v_mount->mnt_iflag & IMNT_HAS_TRANS) == 0 ||
+           fstrans_is_owner(vp->v_mount));
+       VSTATE_ASSERT_UNLOCKED(vp, VS_ACTIVE);
+
+       /* Remove from vnode cache. */
+       hash = vcache_hash(&vip->vi_key);
+       mutex_enter(&vcache_lock);
+       KASSERT(vip == vcache_hash_lookup(&vip->vi_key, hash));
+       SLIST_REMOVE(&vcache_hashtab[hash & vcache_hashmask],
+           vip, vnode_impl, vi_hash);
+       vip->vi_key.vk_mount = dead_rootmount;
+       vip->vi_key.vk_key_len = 0;
+       vip->vi_key.vk_key = NULL;
+       mutex_exit(&vcache_lock);
+
+       /*
+        * Disassociate the underlying file system from the vnode.
+        * VOP_INACTIVE leaves the vnode locked; VOP_RECLAIM unlocks
+        * the vnode, and may destroy the vnode so that VOP_UNLOCK
+        * would no longer function.
+        */
+       if (vn_lock(vp, LK_EXCLUSIVE)) {
+               vnpanic(vp, "%s: cannot lock", __func__);
+       }
+       VOP_INACTIVE(vp, &recycle);
+       KASSERT((vp->v_vflag & VV_LOCKSWORK) == 0 ||
+           VOP_ISLOCKED(vp) == LK_EXCLUSIVE);
+       if (VOP_RECLAIM(vp)) {
+               vnpanic(vp, "%s: cannot reclaim", __func__);
+       }
+
+       /* Purge name cache. */
+       cache_purge(vp);
+
+       /* Done with purge, change operations vector. */
+       mutex_enter(vp->v_interlock);
+       vp->v_op = spec_vnodeop_p;
+       vp->v_vflag |= VV_MPSAFE;
+       vp->v_vflag &= ~VV_LOCKSWORK;
+       mutex_exit(vp->v_interlock);
+
+       /*
+        * Move to dead mount.  Must be after changing the operations
+        * vector as vnode operations enter the mount before using the
+        * operations vector.  See sys/kern/vnode_if.c.
+        */
+       vfs_ref(dead_rootmount);
+       vfs_insmntque(vp, dead_rootmount);
+
+       vrele(vp);
+}
+
+/*
  * Update outstanding I/O count and do wakeup if requested.
  */
 void
diff -r 3687fe4ce6a6 -r 13863d9730ed sys/sys/vnode_impl.h
--- a/sys/sys/vnode_impl.h      Mon Aug 21 08:56:45 2017 +0000
+++ b/sys/sys/vnode_impl.h      Mon Aug 21 09:00:21 2017 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vnode_impl.h,v 1.15 2017/06/04 08:02:26 hannken Exp $  */
+/*     $NetBSD: vnode_impl.h,v 1.16 2017/08/21 09:00:21 hannken Exp $  */
 
 /*-
  * Copyright (c) 2016 The NetBSD Foundation, Inc.
@@ -119,6 +119,7 @@
        vnalloc_marker(struct mount *);
 void   vnfree_marker(vnode_t *);
 bool   vnis_marker(vnode_t *);
+void   vcache_make_anon(vnode_t *);
 int    vcache_vget(vnode_t *);
 int    vcache_tryvget(vnode_t *);
 int    vfs_drainvnodes(void);