[src/trunk]: src Apply patch from Ian D. Leroux in PR bin/51019:

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

details:   https://anonhg.NetBSD.org/src/rev/fb55c92fa19b
branches:  trunk
changeset: 836481:fb55c92fa19b
user:      martin <martin%NetBSD.org@localhost>
date:      Fri Oct 19 14:11:12 2018 +0000

description:
Apply patch from Ian D. Leroux in PR bin/51019:
when unmounting tmpfs file systems at shutdown time, avoid unmounting
a tmpfs created by init on /dev - behaviour overridable from rc.conf.
By default all tmpfs that have device nodes are not mounted.

diffstat:

 etc/defaults/rc.conf     |   8 +++++++-
 etc/rc.d/swap1           |  39 ++++++++++++++++++++++++++++++++++++---
 share/man/man5/rc.conf.5 |  23 +++++++++++++++++++++--
 3 files changed, 64 insertions(+), 6 deletions(-)

diffs (128 lines):

diff -r a582ee6f8a05 -r fb55c92fa19b etc/defaults/rc.conf
--- a/etc/defaults/rc.conf      Fri Oct 19 14:06:13 2018 +0000
+++ b/etc/defaults/rc.conf      Fri Oct 19 14:11:12 2018 +0000
@@ -1,4 +1,4 @@
-#      $NetBSD: rc.conf,v 1.145 2018/09/23 07:24:19 maxv Exp $
+#      $NetBSD: rc.conf,v 1.146 2018/10/19 14:11:12 martin Exp $
 #
 # /etc/defaults/rc.conf --
 #      default configuration of /etc/rc.conf
@@ -99,6 +99,12 @@
                        # partitions and don't want to be warned about it.
 swapoff=YES            # Remove block-type swap partitions upon shutdown
                        # This defaults to yes, so that raids shutdown cleanly
+swapoff_umount=auto    # Set to 'manual' to umount the tmpfs partitions listed
+                       # in swapoff_umount_fs before removing swap. Set to
+                       # 'auto' to umount all tmpfs paritions that contain
+                       # no device nodes.
+swapoff_umount_fs=     # space-separated list of tmpfs mount points to umount
+                       # before removing swap if swapoff_umount=manual
 
 # Concatenated disk driver.
 #
diff -r a582ee6f8a05 -r fb55c92fa19b etc/rc.d/swap1
--- a/etc/rc.d/swap1    Fri Oct 19 14:06:13 2018 +0000
+++ b/etc/rc.d/swap1    Fri Oct 19 14:11:12 2018 +0000
@@ -1,6 +1,6 @@
 #!/bin/sh
 #
-# $NetBSD: swap1,v 1.12 2015/04/20 18:01:46 prlw1 Exp $
+# $NetBSD: swap1,v 1.13 2018/10/19 14:11:12 martin Exp $
 #
 
 # PROVIDE: localswap
@@ -13,6 +13,40 @@
 start_cmd="swap1_start"
 stop_cmd="swap1_stop"
 
+dev_free_tmpfs()
+{
+       # Generate a list of tmpfs filesystems that contain no device nodes,
+       # which can presumably be unmounted safetly at shutdown time.
+       # Filenames are quoted and the list contains no unquoted newlines,
+       # so that the output can be reparsed as a single argument list.
+       mount -t tmpfs | while read -r line
+       do
+               fs=${line#tmpfs on }
+               fs=${fs% type tmpfs*}
+               find -x "${fs}" \( -type b -or -type c \) -exit 1 &&
+                       echo -n "'${fs}' "
+       done
+}
+
+umount_vm_consumers()
+{
+       case ${swapoff_umount} in
+               auto)
+                       swapoff_umount_fs="$(dev_free_tmpfs)"
+                       ;;
+               manual)
+                       # swapoff_umount_fs set manually
+                       ;;
+       esac
+       # eval so that quotes within $swapoff_umount_fs are parsed properly
+       eval set -- "${swapoff_umount_fs}"
+       for fs in "$@"
+       do
+               echo "Forcibly unmounting ${fs}"
+               umount -ft tmpfs "${fs}"
+       done
+}
+
 #              Add all block-type swap devices; these might be necessary
 #              during disk checks.
 #
@@ -31,8 +65,7 @@
 swap1_stop()
 {
        if checkyesno swapoff || [ -n "$rc_force" ]; then
-               echo "Forcibly unmounting tmpfs filesystems"
-               umount -aft tmpfs
+               umount_vm_consumers
                echo "Removing block-type swap devices"
                swapctl -U -t blk || [ $? = 2 ]
        fi
diff -r a582ee6f8a05 -r fb55c92fa19b share/man/man5/rc.conf.5
--- a/share/man/man5/rc.conf.5  Fri Oct 19 14:06:13 2018 +0000
+++ b/share/man/man5/rc.conf.5  Fri Oct 19 14:11:12 2018 +0000
@@ -1,4 +1,4 @@
-.\"    $NetBSD: rc.conf.5,v 1.177 2018/10/01 11:16:04 uwe Exp $
+.\"    $NetBSD: rc.conf.5,v 1.178 2018/10/19 14:11:12 martin Exp $
 .\"
 .\" Copyright (c) 1996 Matthew R. Green
 .\" All rights reserved.
@@ -55,7 +55,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd September 23, 2018
+.Dd October 19, 2018
 .Dt RC.CONF 5
 .Os
 .Sh NAME
@@ -353,6 +353,25 @@
 Boolean value.
 Remove block-type swap devices at shutdown time.
 Useful if swapping onto RAIDframe devices.
+.It Sy swapoff_umount
+.Dq "auto"
+or
+.Dq "manual" .
+Before removing block-type swap devices, it is wise to unmount tmpfs filesystems to avoid having to swap their contents back into RAM.
+By default 
+.Dq ( "auto" )
+all tmpfs filesystems that contain no device nodes are unmounted.
+Set to 
+.Dq "manual"
+to explicitly specify which filesystems to unmount before removing swap.
+.It Sy swapoff_umount_fs
+A space-separated list of absolute paths to tmpfs mount points.
+If 
+.Sy swapoff_umount
+is set to
+.Dq "manual" ,
+these tmpfs filesystems will be forcibly unmounted before removing block-type
+swap devices.
 .It Sy var_shm_symlink
 A path.
 If set, names a path that