From 0bf6e572bd446c6a6cbbafc8861616080d31cdb1 Mon Sep 17 00:00:00 2001
From: Mateusz Piotrowski <0mp@FreeBSD.org>
Date: Tue, 12 Oct 2021 10:40:36 +0200
Subject: [PATCH] rc.d/linux: Attempt to mount only if necessary

Currently, if the linux service is run twice, mount(8) fails with:

    mount: linprocfs: Device busy
    mount: linsysfs: Device busy
    mount: devfs: Device busy
    mount: fdescfs: Device busy
    mount: tmpfs: Device busy

It is a bit more user-friendly if before running mount(8) the service
checks if there are any file systems left to be mounted. This patch
implements this behavior.

Also, while here, create mount points directories (as suggested by
otis).

Reviewed by:	trasz
Approved by:	trasz (src)
Differential Revision:	https://reviews.freebsd.org/D32463

(cherry picked from commit 5690261858b6bd8f7d09eda2ae74f3def2d69a01)
---
 libexec/rc/rc.d/linux | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/libexec/rc/rc.d/linux b/libexec/rc/rc.d/linux
index 2cf32a1ecec3..adb9f4c64bad 100755
--- a/libexec/rc/rc.d/linux
+++ b/libexec/rc/rc.d/linux
@@ -15,6 +15,17 @@ rcvar="linux_enable"
 start_cmd="${name}_start"
 stop_cmd=":"
 
+linux_mount() {
+	local _fs _mount_point
+	_fs="$1"
+	_mount_point="$2"
+	shift 2
+	if ! mount | grep -q "^$_fs on $_mount_point ("; then
+		mkdir -p "$_mount_point"
+		mount "$@" -t "$_fs" "$_fs" "$_mount_point"
+	fi
+}
+
 linux_start()
 {
 	local _emul_path _tmpdir
@@ -61,12 +72,12 @@ linux_start()
 		sysctl kern.elf32.fallback_brand=3 > /dev/null
 	fi
 
-	if checkyesno linux_mounts_enable; then 
-		mount -o nocover -t linprocfs linprocfs "${_emul_path}/proc"
-		mount -o nocover -t linsysfs linsysfs "${_emul_path}/sys"
-		mount -o nocover -t devfs devfs "${_emul_path}/dev"
-		mount -o nocover,linrdlnk -t fdescfs fdescfs "${_emul_path}/dev/fd"
-		mount -o nocover,mode=1777 -t tmpfs tmpfs "${_emul_path}/dev/shm"
+	if checkyesno linux_mounts_enable; then
+		linux_mount linprocfs "${_emul_path}/proc" -o nocover
+		linux_mount linsysfs "${_emul_path}/sys" -o nocover
+		linux_mount devfs "${_emul_path}/dev" -o nocover
+		linux_mount fdescfs "${_emul_path}/dev/fd" -o nocover,linrdlnk
+		linux_mount tmpfs "${_emul_path}/dev/shm" -o nocover,mode=1777
 	fi
 }