[src/trunk]: src/sys Reorganize uvm_swap_shutdown() a bit, make sure the vnod...

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

details:   https://anonhg.NetBSD.org/src/rev/bf2a99770794
branches:  trunk
changeset: 1018763:bf2a99770794
user:      hannken <hannken%NetBSD.org@localhost>
date:      Tue Feb 16 09:56:32 2021 +0000

description:
Reorganize uvm_swap_shutdown() a bit, make sure the vnode gets
locked and referenced across the call to swap_off() and finally
use it from vfs_unmountall1() to remove swap after unmounting
the last file system.

Adresses PR kern/54969 (Disk cache is no longer flushed on shutdown)

diffstat:

 sys/kern/vfs_mount.c |  14 ++++++++++++--
 sys/uvm/uvm_swap.c   |  20 ++++++++------------
 2 files changed, 20 insertions(+), 14 deletions(-)

diffs (101 lines):

diff -r ecb436ea39a2 -r bf2a99770794 sys/kern/vfs_mount.c
--- a/sys/kern/vfs_mount.c      Tue Feb 16 09:54:17 2021 +0000
+++ b/sys/kern/vfs_mount.c      Tue Feb 16 09:56:32 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vfs_mount.c,v 1.85 2020/11/19 10:47:47 hannken Exp $   */
+/*     $NetBSD: vfs_mount.c,v 1.86 2021/02/16 09:56:32 hannken Exp $   */
 
 /*-
  * Copyright (c) 1997-2020 The NetBSD Foundation, Inc.
@@ -67,7 +67,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_mount.c,v 1.85 2020/11/19 10:47:47 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_mount.c,v 1.86 2021/02/16 09:56:32 hannken Exp $");
 
 #include <sys/param.h>
 #include <sys/kernel.h>
@@ -94,6 +94,8 @@
 #include <miscfs/genfs/genfs.h>
 #include <miscfs/specfs/specdev.h>
 
+#include <uvm/uvm_swap.h>
+
 enum mountlist_type {
        ME_MOUNT,
        ME_MARKER
@@ -1022,6 +1024,7 @@
 vfs_unmountall1(struct lwp *l, bool force, bool verbose)
 {
        struct mount *mp;
+       mount_iterator_t *iter;
        bool any_error = false, progress = false;
        uint64_t gen;
        int error;
@@ -1056,6 +1059,13 @@
        if (any_error && verbose) {
                printf("WARNING: some file systems would not unmount\n");
        }
+       /* If the mountlist is empty it is time to remove swap. */
+       mountlist_iterator_init(&iter);
+       if (mountlist_iterator_next(iter) == NULL) {
+               uvm_swap_shutdown(l);
+       }
+       mountlist_iterator_destroy(iter);
+
        return progress;
 }
 
diff -r ecb436ea39a2 -r bf2a99770794 sys/uvm/uvm_swap.c
--- a/sys/uvm/uvm_swap.c        Tue Feb 16 09:54:17 2021 +0000
+++ b/sys/uvm/uvm_swap.c        Tue Feb 16 09:56:32 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: uvm_swap.c,v 1.200 2020/10/07 17:51:50 chs Exp $       */
+/*     $NetBSD: uvm_swap.c,v 1.201 2021/02/16 09:56:32 hannken Exp $   */
 
 /*
  * Copyright (c) 1995, 1996, 1997, 2009 Matthew R. Green
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uvm_swap.c,v 1.200 2020/10/07 17:51:50 chs Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uvm_swap.c,v 1.201 2021/02/16 09:56:32 hannken Exp $");
 
 #include "opt_uvmhist.h"
 #include "opt_compat_netbsd.h"
@@ -1152,27 +1152,23 @@
                        if ((sdp->swd_flags & (SWF_INUSE|SWF_ENABLE)) == 0)
                                continue;
 #ifdef DEBUG
-                       printf("\nturning off swap on %s...",
-                           sdp->swd_path);
+                       printf("\nturning off swap on %s...", sdp->swd_path);
 #endif
+                       /* Have to lock and reference vnode for swap_off(). */
                        if (vn_lock(vp = sdp->swd_vp, LK_EXCLUSIVE)) {
                                error = EBUSY;
-                               vp = NULL;
-                       } else
-                               error = 0;
-                       if (!error) {
+                       } else {
+                               vref(vp);
                                error = swap_off(l, sdp);
+                               vput(vp);
                                mutex_enter(&uvm_swap_data_lock);
                        }
                        if (error) {
                                printf("stopping swap on %s failed "
                                    "with error %d\n", sdp->swd_path, error);
-                               TAILQ_REMOVE(&spp->spi_swapdev, sdp,
-                                   swd_next);
+                               TAILQ_REMOVE(&spp->spi_swapdev, sdp, swd_next);
                                uvmexp.nswapdev--;
                                swaplist_trim();
-                               if (vp)
-                                       vput(vp);
                        }
                        goto again;
                }